WO2025259335A2

WO2025259335A2 - Magnetic tunability of magnetic supercluster particles

Info

Publication number: WO2025259335A2
Application number: PCT/US2025/019578
Authority: WO
Inventors: T. Randall Lee; Minh Dang Nguyen
Original assignee: University of Houston System
Current assignee: University of Houston System
Priority date: 2024-03-15
Filing date: 2025-03-12
Publication date: 2025-12-18
Anticipated expiration: 2026-09-15
Also published as: WO2025259335A3

Abstract

This invention relates to magnetic supercluster particles and uses thereof. In various embodiments, the magnetic supercluster particles are made by variations of core/shell FeO@Fe₃O₄ nanoparticles with different sizes and shape.

Description

MAGNETIC TUNABILITY OF MAGNETIC SUPERCLUSTER PARTICLES CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 63/565,763 filed March 15, 2024, U.S. Provisional Patent Application No. 63/656,960 filed June 6, 2024, and U.S. Provisional Patent Application No. 63/759,667 filed February 18, 2025, the contents of each of which are incorporated herein by reference in their entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] This invention was made with government support under Grant No. FA9550-23-1- 0581 awarded by the U.S. Air Force Office of Scientific Research. The government has certain rights in the invention. FIELD OF THE INVENTION [0003] This invention relates to magnetic supercluster particles and uses thereof. BACKGROUND [0004] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. [0005] Magnetic iron oxide nanoparticles (IONPs) possessing superparamagnetic (SPM) properties offer enormous potential in advanced biomedical applications, including magnetic resonance imaging (MRI), drug delivery, magnetic hyperthermia, and biosensing. However, 4913-4975-3383.1 Page 1 of 144 ^{094876-000024WOPT} currently known magnetic iron oxide nanoparticles possess various limitations hindering their application and further development. Therefore, there is an ongoing need for new and improved materials that overcome these limitations. The embodiments of the present invention address these needs. SUMMARY OF THE INVENTION [0006] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. In some embodiments, each magnetic nanoparticle is independently a nanosphere or a nanocube. In some embodiments, each magnetic nanoparticle independently has a particle size of at least 12 nm. In some embodiments, each magnetic nanoparticle independently has a particle size of at least 20 nm. In some embodiments, the magnetic supercluster particle has a diameter of at least 120 nm. In some embodiments, the magnetic supercluster particle has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T). In some embodiments, the magnetic supercluster particle has a blocking temperature (T_B) of at least 220 Kelvin (K). In some embodiments, the magnetic supercluster particle has at least one superparamagnetic property. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. [0007] In various embodiments, the present invention provides a composition, comprising at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a ^{4913-4975-3383.1} Page 2 of 144 094876-000024WOPT core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. [0008] In various embodiments, the present invention provides an article of manufacture, comprising at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. [0009] In various embodiments, the present invention provides a magnetic resonance imaging (MRI) contrast agent, comprising at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. [0010] In various embodiments, the present invention provides a magnetic resonance imaging (MRI) probe, comprising at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. [0011] In various embodiments, the present invention provides a sensor, comprising at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle ^{4913-4975-3383.1} Page 3 of 144 094876-000024WOPT comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. [0012] In various embodiments, the present invention provides an article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. [0013] In various embodiments, the present invention provides a drug delivery device, comprising at least one magnetic supercluster particle, wherein the at least one magnetic supercluster particle comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the at least one magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the at least one magnetic supercluster particle through an intermolecular interaction. BRIEF DESCRIPTION OF THE DRAWINGS [0014] Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. [0015] FIG.1A – FIG.1I depicts in accordance with various embodiments of the invention, TEM images of (FIG.1A – FIG.1E) iron oxide nanospheres and (FIG.1F – FIG.1I) iron oxide nanocubes with tunable sizes. Size of nanoparticles (diameter for the nanospheres and edge length for the nanocubes) in nm. ^{4913-4975-3383.1} Page 4 of 144 094876-000024WOPT [0016] FIG. 2A – FIG. 2B depicts in accordance with various embodiments of the invention, XRD Patterns of (FIG.2A) iron oxide nanospheres and (FIG.2B) iron oxide nanocubes. Size of nanoparticles (diameter for the nanospheres and edge length for the nanocubes) in nm. [0017] FIG. 3A – FIG. 3F depicts in accordance with various embodiments of the invention, schematic illustration of the formation of superclusters (FIG.3A) and SEM images of superclusters formed by (FIG.3B) nanocubes (size 10.2 nm), (FIG.3C) nanocubes (size 11.8 nm), (FIG. 3D) nanospheres (size 13.1 nm), (FIG. 3E) nanospheres (size 15.6 nm), and (FIG. 3F) nanospheres (size 21.8 nm). [0018] FIG. 4A – FIG. 4B depicts in accordance with various embodiments of the invention, saturation magnetization (M_S) versus particle size relation for core/shell IONPs: (FIG. 4A) nanospheres and (FIG.4B) nanocubes. [0019] FIG. 5A – FIG. 5E depicts in accordance with various embodiments of the invention, TEM images of iron oxide nanospheres (FIG.5A – FIG.5C) and iron oxide nanocubes (FIG.5D – FIG.5E). [0020] FIG. 6A – FIG. 6E depicts in accordance with various embodiments of the invention, schematic illustration of the formation of superclusters (FIG.6A) and SEM images of superclusters formed by different sizes and shapes of nanoparticles (FIG.6B – FIG.6E). [0021] FIG. 7A – FIG. 7B depicts in accordance with various embodiments of the invention, (FIG. 7A) Magnetization vs. Field (300 K), and (FIG. 7B) Magnetization vs. Temperature Measurement at 100 Oe. [0022] FIG. 8A – FIG. 8B depicts in accordance with various embodiments of the invention, polycrystalline structure (FIG.8A) and superclusters structure (FIG.8B). [0023] FIG. 9A – FIG. 9G depicts in accordance with various embodiments of the invention, High-resolution TEM and FFT of (FIG.9A – FIG.9C) nanospheres size 28.3 nm, and (FIG.9D – FIG.9G) nanocubes size 18.0 nm. [0024] FIG. 10A – FIG. 10B depicts in accordance with various embodiments of the invention, (FIG.10A) High-resolution Fe 2p XPS spectra and, (FIG.10B) Raman spectra of iron oxide nanospheres (NSs) and nanocubes (NCs). [0025] FIG. 11A – FIG. 11F depicts in accordance with various embodiments of the invention, (FIG.11A) schematic illustration of the formation of superclusters, and SEM images of superclusters formed by (FIG.11B) nanocubes (10.2 nm), (FIG.11C) nanocubes (11.8 nm), (FIG. ^{4913-4975-3383.1} Page 5 of 144 094876-000024WOPT 11D) nanospheres (13.1 nm), (FIG.11E) nanospheres (15.6 nm), and (FIG.11F) nanospheres (21.8 nm). The supercluster size was calculated based on a size distribution analysis and is specified in the top right corner of each image, while the size and shape of the individual nanoparticles (e.g., nanosphere or nanocube) is specified in the bottom right corner. [0026] FIG. 12 depicts in accordance with various embodiments of the invention, a schematic illustration of a chemical synthesis strategy for fabricating magnetic supercluster particles with tunable size and shape of the constituent magnetic nanoparticles, allowing for the fine-tuning of superparamagnetic properties. This method highlights the opportunities for producing magnetic nanoparticles in supercluster form, with similar particle sizes but having different superparamagnetic properties. This method highlights the opportunities for producing supercluster particles with similar particle sizes but having different superparamagnetic properties. This is a useful approach for designing nanoparticle structure and properties for a wide range of applications and exploring the unique features of nano-magnetism. [0027] FIG.13 depicts in accordance with various embodiments of the invention, atomic resolution TEM image and FFT of nanospheres size 9.8 nm. [0028] FIG. 14A – FIG. 14F depicts in accordance with various embodiments of the invention, (FIG.14A) field dependence of magnetization (M(H)) at 300 K, and (FIG.14B – FIG. 14F) temperature dependence of magnetization (M(T)) at 100 Oe for iron oxide nanospheres of varying sizes. [0029] FIG. 15A – FIG. 15E depicts in accordance with various embodiments of the invention, (FIG.15A) field dependence of magnetization (M(H)) at 300 K and (FIG.15B – FIG. 15E) temperature dependence of magnetization (M(T)) at 100 Oe for iron oxide nanocubes of varying sizes. [0030] FIG. 16A – FIG. 16D depicts in accordance with various embodiments of the invention, field dependence of magnetization (M(H)) at 300 K for iron oxide nanocubes (NCs) sized 10.2 ± 0.9 nm (FIG. 16A) and 11.8 ± 1.3 nm (FIG. 16B), along with their corresponding superclusters (SCs); and temperature dependence of magnetization (M(T)) for iron oxide NCs sized 10.2 nm ± 0.9 nm (FIG.16C) and 11.8 ± 1.3 nm (FIG.16D), and their corresponding SCs. [0031] FIG. 17A – FIG. 17F depicts in accordance with various embodiments of the invention, field dependence of magnetization (M(H)) at 300 K for iron oxide nanospheres (NSs) sized 13.1 ± 1.0 nm (FIG.17A), 15.6 ± 1.3 nm (FIG.17B), and 21.8 ± 2.0 nm (FIG.17C), along ^{4913-4975-3383.1} Page 6 of 144 094876-000024WOPT with their corresponding superclusters (SCs); and temperature dependence of magnetization (M(T)) for iron oxide NSs sized 13.1 ± 1.0 nm (FIG.17D), 15.6 ± 1.3 nm (FIG.17E), and 21.8 ± 2.0 nm (FIG.17F), and their corresponding SCs. [0032] FIG. 18A – FIG. 18F depicts in accordance with various embodiments of the invention, size distribution of supercluster particles (presented in FIG.11A – FIG.11F) synthesized from different sizes and shapes of nanoparticles. [0033] FIG. 19A – FIG. 19B depicts in accordance with various embodiments of the invention, the structure of a polycrystalline particle (FIG.19A), and the structure of a supercluster particle (FIG.19B). [0034] FIG. 20A – FIG. 20B depicts in accordance with various embodiments of the invention, M(H) ZFC and 3T-FC at 10 K of (FIG.20A) nanocubes size 18.0 ± 1.4 nm, and (FIG. 20B) nanospheres size 28.3 ± 2.5 nm. [0035] FIG. 21 depicts in accordance with various embodiments of the invention, M(H) ZFC and 3T-FC at 10 K of superclusters made by nanospheres size 21.8 ± 2.0 nm. DETAILED DESCRIPTION OF THE INVENTION [0036] All references cited herein are incorporated by reference in their entirety as though fully set forth. Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. [0037] One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, various features of embodiments of the invention. Indeed, the present invention is in no way limited to the methods and materials described. For purposes of the present invention, the following terms are defined below. For convenience, certain terms employed herein, in the specification, examples and appended claims are collected here. [0038] Unless stated otherwise, or implicit from context, the following terms and phrases include the meanings provided below. Unless explicitly stated otherwise, or apparent from context, the terms and phrases below do not exclude the meaning that the term or phrase has acquired in ^{4913-4975-3383.1} Page 7 of 144 094876-000024WOPT the art to which it pertains. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should be understood that this invention is not limited to the particular methodology, protocols, and reagents, etc., described herein and as such can vary. The definitions and terminology used herein are provided to aid in describing particular embodiments, and are not intended to limit the claimed invention, because the scope of the invention is limited only by the claims. [0039] As used herein the term “comprising” or “comprises” is used in reference to compositions, methods, systems, articles of manufacture, apparatus, and respective component(s) thereof, that are useful to an embodiment, yet open to the inclusion of unspecified elements, whether useful or not. It will be understood by those within the art that, in general, terms used herein are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). Although the open- ended term “comprising,” as a synonym of terms such as including, containing, or having, is used herein to describe and claim the invention, the present invention, or embodiments thereof, may alternatively be described using alternative terms such as “consisting of” or “consisting essentially of.” [0040] Unless stated otherwise, the terms “a” and “an” and “the” and similar references used in the context of describing a particular embodiment of the application (especially in the context of claims) can be construed to cover both the singular and the plural. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (for example, “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the application and does not pose a limitation on the scope of the application otherwise claimed. The abbreviation, “e.g.” is derived from the Latin exempli gratia, and is used herein to indicate a non-limiting example. Thus, the abbreviation “e.g.” is synonymous with the ^{4913-4975-3383.1} Page 8 of 144 094876-000024WOPT term “for example.” No language in the specification should be construed as indicating any non- claimed element essential to the practice of the application. [0041] “Optional" or “optionally” means that the subsequently described circumstance may or may not occur, so that the description includes instances where the circumstance occurs and instances where it does not. [0042] In some embodiments, the numbers expressing quantities of reagents, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. [0043] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims. [0044] In various embodiments, compounds of the present invention as disclosed herein may be synthesized using any synthetic method available to one of skill in the art. Non-limiting examples of synthetic methods used to prepare various embodiments of compounds of the present invention are disclosed in the Examples section herein. [0045] In various embodiments the present invention provides Fine-Tuning the Superparamagnetic Properties of FeO@Fe₃O₄ Core/Shell Nanoparticles and Superclusters by Controlling Size and Shape. ^{4913-4975-3383.1} Page 9 of 144 094876-000024WOPT [0046] In some embodiments, a supercluster is a supercluster particle. In some embodiments, a supercluster is a magnetic supercluster. In some embodiments, a supercluster is a magnetic supercluster particle. In some embodiments, a supercluster particle is a magnetic supercluster particle. In some embodiments, a supercluster is a superparamagnetic supercluster. In some embodiments, a supercluster is a superparamagnetic supercluster particle. In some embodiments, a superparamagnetic supercluster is a superparamagnetic supercluster particle. In some embodiments, a supercluster is in dry powder form. In some embodiments, a supercluster is dispersed in a liquid carrier. In some embodiments, a magnetic supercluster particle is in dry powder form. In some embodiments, a magnetic supercluster particle is dispersed in a liquid carrier. [0047] In various embodiments of the present invention a supercluster particle, comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the supercluster particle through an intermolecular interaction. In a supercluster particle of the present invention each magnetic nanoparticle is a discrete entity within the supercluster particle. For example, the structure of a supercluster particle of the present invention is shown in FIG.19B. In some embodiments of the present invention, the supercluster particle is a magnetic supercluster particle. [0048] A supercluster particle of the present invention is different and distinguishable from a polycrystalline iron oxide nanoparticle. A polycrystalline iron oxide nanoparticle is an agglomeration of iron oxide primary crystals, where each iron oxide primary crystal is not a discrete entity within the polycrystalline iron oxide nanoparticle. In a polycrystalline iron oxide nanoparticle each iron oxide primary crystal is merely separated by and held together by a grain boundary. A grain boundary is the interface between individual iron oxide primary crystals in a polycrystalline iron oxide nanoparticle. Grain boundaries essentially hold the iron oxide primary crystals together within the polycrystalline iron oxide nanoparticle. For example, the structure of a polycrystalline iron oxide nanoparticle is shown in FIG.19A. [0049] A supercluster particle of the present invention is different and distinguishable from a large polycrystalline iron oxide nanoparticle, which is sometimes referred to as a superparticle. ^{4913-4975-3383.1} Page 10 of 144 094876-000024WOPT Superparticles are large polycrystalline iron oxide nanoparticles and have a particle size (i.e., diameter) of at least 150 nm. A superparticle is a large polycrystalline iron oxide nanoparticle and is an agglomeration of iron oxide primary crystals, where each iron oxide primary crystal is not a discrete entity within the polycrystalline iron oxide nanoparticle. In a superparticle each iron oxide primary crystal is merely separated by and held together by a grain boundary. A grain boundary is the interface between individual iron oxide primary crystals in a polycrystalline iron oxide nanoparticle. Grain boundaries essentially hold the iron oxide primary crystals together within the polycrystalline iron oxide nanoparticle. For example, the structure of a large polycrystalline iron oxide nanoparticle (also known as a superparticle) is shown in FIG.19A. [0050] Chapter 1 [0051] In various embodiments, the present invention provides Fine-tuning the Superparamagnetic Properties of Iron Oxide Nanoparticles by Controlling Size, Shape, and Forming Superclusters. [0052] In various embodiments, the present invention provides forming iron oxide superclusters with tunable sizes and shapes of nanoparticles, which opens opportunities for fine- tuning the SPM properties. In various embodiments, the present invention provides forming superclusters for fine-tuning the SPM properties. [0053] In various embodiments, the present invention provides that nanocubes have higher values of saturation magnetization and higher blocking temperature (T_B) than nanospheres with similar volumes. [0054] In various embodiments, the present invention provides nanocubes that have higher values of saturation magnetization than nanospheres with similar volumes. [0055] In various embodiments, the present invention provides superclusters which displayed enhancement in magnetization and their blocking temperature (T_B) shifted towards higher temperature with more flattening ZFC maxima feature. [0056] In various embodiments of the present invention, the enhancement in magnetization of superclusters is more significant at low magnetic field (<0.5 T). [0057] In various embodiments, the present invention provides a strategy for the precise adjustment of the superparamagnetic properties of iron oxide nanoparticles through the formation of superclusters with adjustable sizes and shapes of constituent nanoparticles. Inspired by our previous work which aimed at controlling the size and crystallinity of polycrystalline iron oxide ^{4913-4975-3383.1} Page 11 of 144 094876-000024WOPT nanoparticles to modulate their magnetic properties between ferrimagnetic and superparamagnetic states, the present invention introduces an enhanced degree of flexibility in manipulating the structure and magnetic properties of iron oxide nanoparticles, particularly emphasizing the refinement of superparamagnetic states. Without limitation, the methodology proposed in the present invention is highlighted as follows: [0058] In various embodiments, the present invention provides the synthesis of iron oxide nanospheres and nanocubes with dimensions ranging from 10 nm to 28 nm and 10 nm to 18 nm, respectively. These nanoparticles, which adopt a core-shell FeO@Fe₃O₄ structure coated with an oleic acid capping agent, exhibit superparamagnetic properties. The nanoparticles function as the foundational units for the assembly to form supercluster particles. [0059] In various embodiments, the present invention provides the formation of supercluster particles achieved through self-assembly of IONPs using oil droplets in micro- emulsion as templates. [0060] In various embodiments, the present invention provides that the magnetic characteristics of the superclusters are influenced by the magnetic properties of the individual nanoparticles. These, in turn, can be customized by selecting nanoparticles with specific sizes and shapes. [0061] In various embodiments, the present invention provides superclusters that exhibit enhanced superparamagnetic (SPM) properties. The magnetic properties of these superclusters, including saturation magnetization and blocking temperature, can be precisely tuned based on the structure of the constituent nanoparticles. [0062] In various embodiments, the present invention provides superclusters endowed with improved and adjustable SPM properties that hold significant potential for advanced biomedical applications, such as magnetic resonance imaging, magnetic hyperthermia, biosensing, and controlled drug delivery. [0063] In addition, applications in sensor systems, energy, and electronic devices, which require nanoparticles with adjustable superparamagnetic (SPM) properties, could find various embodiments of the present invention as a useful method to fabricate the desired nanoparticles. [0064] Magnetic iron oxide nanoparticles (IONPs) with superparamagnetic (SPM) properties have demonstrated their potential across various biomedical technologies, attributable to their unique magnetic attributes coupled with exceptional biocompatibility. However, SPM ^{4913-4975-3383.1} Page 12 of 144 094876-000024WOPT IONPs typically reside within the single-domain size range (<30 nm), exhibiting weak to moderate magnetic properties and raising concerns about deep penetration that may lead to cytotoxicity and biochemical toxicity. Large-size SPM nanoparticles, within the range of several hundred nanometers, could represent a viable alternative, providing stronger magnetization for magnetic manipulation and reducing the risk of deep tissue penetration. In the present invention, we outline a strategy for the precise adjustment of the SPM properties of large-size SPM nanoparticles by assembling supercluster particles with adjustable structures of their constituent nanoparticles. The SPM properties of these supercluster particles can be modified by selecting the size and shape of the constituent nanoparticles. The nanoparticles employed in the formation of supercluster particles are iron oxide nanospheres and nanocubes, featuring FeO@Fe₃O₄ core-shell structures. Conclusive experimental evidence has confirmed the enhanced superparamagnetic properties of the supercluster particles and their capability for fine-tuned SPM characteristics. With such advancements in magnetic tunability, the supercluster particles are anticipated to play a significant role in advanced biomedical technologies. [0065] In various embodiments the present invention provides a practical approach to fabricating large-size superparamagnetic iron oxide nanoparticles (SPM NPs) (above 100 nm) with the ability to finely tune the SPM properties by selecting the size and shape of the nanoparticles for the formation of supercluster structures. Unlike other types of large-size SPM NPs, such as polycrystalline particles or particles encapsulated in polymer or inorganic shells, the supercluster structures of the present invention offer a high degree of flexibility for tuning SPM properties and minimizing the non-magnetic components in the particle structure. Although studies have reported on the formation of superclusters (J. Am. Chem. Soc.2007, 129, 14166–14167, J. Am. Chem. Soc. 2012, 134, 18225–18228, J. Am. Chem. Soc. 2018, 140, 15038–15047), comprehensive investigations into their magnetic properties, specifically the selection of nanoparticles with appropriate sizes and shapes, the formation of superclusters with tunable nanoparticle structures, and the fine-tuning of SPM, have not been conducted. Therefore, the study presented in the present invention is unique and offers significant advantages for tailoring SPM nanoparticles for use in advanced biomedical technologies, including MRI, hyperthermia, and biosensing. [0066] Magnetic iron oxide nanoparticles (IONPs) possessing superparamagnetic (SPM) properties and exceptional biocompatibility demonstrate enormous potential in advanced biomedical applications, including MRI, drug delivery, magnetic hyperthermia, and biosensing ^{4913-4975-3383.1} Page 13 of 144 094876-000024WOPT (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci.2021, 11, 11301; Tran, H.-V.; Ngo, N. M.; Medhi, R.; Srinoi, P.; Liu, T.; Rittikulsittichai, S.; Lee, T. R. Multifunctional Iron Oxide Magnetic Nanoparticles for Biomedical Applications: A Review. Materials 2022, 15, 503). The utility of SPM properties lies in their manipulability and the capability to switch on and off under a magnetic field. In contrast to ferrimagnetic (FiM) or ferromagnetic (FM) properties, SPM properties excel in minimizing particle-particle magnetic interactions, thereby reducing particle aggregation. This enhances the dispersibility of nanoparticles in colloidal solutions and facilitates their redispersion after magnetic separation. Consequently, tailoring the magnetic properties of IONPs by controlling their structure emerges as a crucial strategy for understanding nano-magnetism and optimizing nanoparticles for specific biomedical applications (Gavilán, H.; Kumar Avugadda, S.; Fernández-Cabada, T.; Soni, N.; Cassani, M.; T. Mai, B.; Chantrell, R.; Pellegrino, T. Magnetic Nanoparticles and Clusters for Magnetic Hyperthermia: Optimizing Their Heat Performance and Developing Combinatorial Therapies to Tackle Cancer. Chem. Soc. Rev. 2021, 50, 11614–11667; Gavilán, H.; Posth, O.; Bogart, L. K.; Steinhoff, U.; Gutiérrez, L.; Morales, M. P. How Shape and Internal Structure Affect the Magnetic Properties of Anisometric Magnetite Nanoparticles. Acta Mater. 2017, 125, 416– 424). [0067] Typically, IONPs with SPM properties are single-domain IONPs in the size range < 25 nm (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci. 2021, 11, 11301; Kolhatkar, A. G.; Jamison, A. C.; Litvinov, D.; Willson, R. C.; Lee, T. R. Tuning the Magnetic Properties of Nanoparticles. Int. J. Mol. Sci.2013, 14, 15977–16009). Although the transition size from superparamagnetic (SPM) to ferromagnetic (FM) properties is generally considered to be around 25 nm, this size can vary based on the shapes (e.g., spheres, cubes, rods, etc.) and compositions of the nanoparticles (Fe₃O₄, FeO, γ-Fe₂O₃, α-Fe₂O₃). Additionally, SPM properties can be observed in larger IONPs above 100 nm if the IONPs are secondary structures formed through the stacking of crystals in polycrystalline particles (Xuan, S.; Wang, Y.-X. J.; Yu, J. C.; Cham-Fai Leung, K. Tuning the Grain Size and Particle Size of Superparamagnetic Fe₃O₄ Microparticles. Chem. Mater.2009, 21, 5079–5087; Ge, J.; Hu, Y.; Biasini, M.; Beyermann, W. P.; Yin, Y. Superparamagnetic Magnetite Colloidal Nanocrystal Clusters. Angew. Chem. Int. Ed.2007, ^{4913-4975-3383.1} Page 14 of 144 094876-000024WOPT 46, 4342–4345) or the assembly of iron oxide nanoparticles (Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc. 2007, 129, 14166–14167; Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc.2018, 140, 15038–15047; Wang, T.; Wang, X.; LaMontagne, D.; Wang, Z.; Wang, Z.; Cao, Y. C. Shape-Controlled Synthesis of Colloidal Superparticles from Nanocubes. J. Am. Chem. Soc.2012, 134, 18225–18228). Large SPM IONPs (size > 100 nm) may exist as polycrystalline nanoparticles with small crystallite sizes, (Xuan, S.; Wang, Y.-X. J.; Yu, J. C.; Cham-Fai Leung, K. Tuning the Grain Size and Particle Size of Superparamagnetic Fe₃O₄ Microparticles. Chem. Mater. 2009, 21, 5079–5087; Ganesan, V.; Lahiri, B. B.; Louis, C.; Philip, J.; Damodaran, S. P. Size-Controlled Synthesis of Superparamagnetic Magnetite Nanoclusters for Heat Generation in an Alternating Magnetic Field. J. Mol. Liq. 2019, 281, 315–323) superclusters of single-domain IONPs assembly, (Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc.2007, 129, 14166–14167; Wang, T.; Wang, X.; LaMontagne, D.; Wang, Z.; Wang, Z.; Cao, Y. C. Shape-Controlled Synthesis of Colloidal Superparticles from Nanocubes. J. Am. Chem. Soc.2012, 134, 18225–18228; Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256) or clusters of single-domain SPM IONPs encapsulated in a polymer matrix or an inorganic shell (Yoon, T.-J.; Lee, H.; Shao, H.; Hilderbrand, S. A.; Weissleder, R. Multicore Assemblies Potentiate Magnetic Properties of Biomagnetic Nanoparticles. Adv. Mater.2011, 23, 4793–4797). Among these three types of large SPM IONPs, supercluster particles (assembly of single-domain IONPs) offer flexibility in manipulating the structures of particles in comparison with polycrystalline particles, while minimizing the non- magnetic component, unlike the encapsulated particles. Hence, tailoring the size/shape of superclusters and tuning the size, shape, and compositions of individual nanoparticles are useful for forming numerous unique supercluster structures, which promise remarkable potential in discovering unique magnetic properties and future applications. [0068] While maintaining the benefits of SPM properties, large SPM IONPs offer advantages such as stronger saturation magnetization through the collective close interactions of component SPM particles, facilitating efficient magnetic separation. This advantage holds ^{4913-4975-3383.1} Page 15 of 144 094876-000024WOPT immense potential for biomedical applications, which typically utilize SPM IONPs with sizes < 30 nm. Despite the extensive use of SPM single-domain IONPs in biomedicine, concerns about toxicity persist due to their small size, which may lead to deep penetration and retention in sensitive areas of the body (D, R.; Rao, P. Nanoparticles: Is Toxicity a Concern? EJIFCC 2011, 22, 92–101; Moura, R. P.; Almeida, A.; Sarmento, B. The Role of Non-Endothelial Cells on the Penetration of Nanoparticles through the Blood Brain Barrier. Progress in Neurobiology 2017, 159, 39–49; Kefeni, K. K.; Msagati, T. A. M.; Nkambule, T. TI.; Mamba, B. B. Spinel Ferrite Nanoparticles and Nanocomposites for Biomedical Applications and Their Toxicity. Mater. Sci. Eng. C 2020, 107, 110314). Therefore, utilizing large SPM IONPs with improved magnetization presents an alternative approach with significant potential in biomedicine, deserving more attention and further exploration. Dynabead M280 size 2.8 μm SPM particles (clusters of SPM IONPs dispersed in polymer) are a prominent example of useful large SPM particles in bio-detection and bio- purification (Chen, Y.-T.; Medhi, R.; Nekrashevich, I.; Litvinov, D.; Xu, S.; Lee, T. R. Specific Detection of Proteins Using Exceptionally Responsive Magnetic Particles. Anal. Chem.2018, 90, 6749–6756; Chen, Y.-T.; Kolhatkar, A. G.; Zenasni, O.; Xu, S.; Lee, T. R. Biosensing Using Magnetic Particle Detection Techniques. Sensors 2017, 17, 2300). Recent studies have demonstrated the efficiency of large SPM IONPs as magnetic agents in biosensing and MRI (Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256; Wu, C.; Xu, Y.; Yang, L.; Wu, J.; Zhu, W.; Li, D.; Cheng, Z.; Xia, C.; Guo, Y.; Gong, Q.; Song, B.; Ai, H. Negatively Charged Magnetite Nanoparticle Clusters as Efficient MRI Probes for Dendritic Cell Labeling and In Vivo Tracking. Adv. Funct. Mater. 2015, 25, 3581–3591; Cai, Z.; Wu, C.; Yang, L.; Wang, D.; Ai, H. Assembly-Controlled Magnetic Nanoparticle Clusters as MRI Contrast Agents. ACS Biomater. Sci. Eng. 2020, 6, 2533–2542). In magnetic hyperthermia applications, Teresa Pellegrino’s group reported the use of clusters of iron oxide nanocubes with improved hyperthermia properties. (Niculaes, D.; Lak, A.; Anyfantis, G. C.; Marras, S.; Laslett, O.; Avugadda, S. K.; Cassani, M.; Serantes, D.; Hovorka, O.; Chantrell, R.; Pellegrino, T. Asymmetric Assembling of Iron Oxide Nanocubes for Improving Magnetic Hyperthermia Performance. ACS Nano 2017, 11, 12121–12133). [0069] To date, two routes for producing SPM IONPs with tunable sizes and shapes involve the thermal decomposition of iron(III) acetylacetonate in benzyl ether and the thermal ^{4913-4975-3383.1} Page 16 of 144 094876-000024WOPT decomposition of iron(III) oleate in non-polar solvents (hexadecane, octadecene, tetradecane, docosane) (Kim, D.; Lee, N.; Park, M.; Kim, B. H.; An, K.; Hyeon, T. Synthesis of Uniform Ferrimagnetic Magnetite Nanocubes. J. Am. Chem. Soc. 2009, 131, 454–455; Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large- Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater.2004, 3, 891–895; Muro-Cruces, J.; Roca, A. G.; López-Ortega, A.; Fantechi, E.; del-Pozo-Bueno, D.; Estradé, S.; Peiró, F.; Sepúlveda, B.; Pineider, F.; Sangregorio, C.; Nogues, J. Precise Size Control of the Growth of Fe₃O₄ Nanocubes over a Wide Size Range Using a Rationally Designed One-Pot Synthesis. ACS Nano 2019, 13, 7716–7728; Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core–Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater. 2023, 35, 6201– 6219). The former approach has the advantage of producing a highly pure Fe₃O₄ phase, but the challenge lies in the instability of benzyl ether at high temperatures, impacting reproducibility and scalability. The decomposition of iron(III) oleate forms the FeO phase in the core of Fe₃O₄ particles; however, its reproducibility is relatively higher, making it suitable for larger-scale synthesis. Therefore, employing the thermal decomposition of iron oleates as a tool to produce IONPs with tunable sizes and shapes, followed by the formation of supercluster structures, is essential for establishing a systematic view of the structure-to-properties relation for tuning SPM properties for diverse biomedical applications. [0070] The work described herein initially focuses on the synthesis of iron oxide nanospheres and iron oxide nanocubes through the thermal decomposition of iron oleate, enabling tunable sizes for a comprehensive study of magnetic properties. The composition of these nanoparticle systems includes FeO@Fe₃O₄ core-shell structures, with larger particles tending to exhibit a more pronounced FeO phase. Two important parameters, saturation magnetization and blocking temperature, for different sizes of nanospheres and nanocubes, are investigated for comparison. Experimental data revealed stronger saturation magnetization in iron oxide nanocubes and provided guidelines for selecting IONPs with suitable SPM properties. Additionally, to further tune the SPM properties, superclusters are fabricated using various sizes and shapes of nanoparticles (e.g, iron oxide nanospheres, iron oxide nanocubes). The systematic study of magnetic properties in supercluster particles versus their individual nanoparticles demonstrated a ^{4913-4975-3383.1} Page 17 of 144 094876-000024WOPT significant improvement in saturation magnetization and a shift in blocking temperature toward higher temperatures in superclusters. These magnetic behaviors originate from strong magnetic interactions among the individual nanoparticles within the superclusters, benefiting improved magnetization and performance in advanced biomedical applications. Interestingly, superclusters of similar sizes could exhibit completely different saturation magnetization and blocking temperatures, depending on their constituent nanoparticles. This underscores the potential for fine- tuning the SPM properties of IONPs in the multi-domain size range. [0071] Structural and Magnetic Characterization of Iron Oxide Nanoparticles. [0072] The structure and magnetic properties of IONPs with cubic and spherical shapes were studied by characterizing the nanoparticles with TEM, XRD, and SQUID. In the context of this paper, the size of particles is defined as the diameter for spherical shapes and edge length for cubic shapes. FIG. 1A – FIG. 1I presents the TEM images of Iron Oxide Nanospheres (IONSs) with average sizes from 10 nm to 28 nm (FIG.1A – FIG.1E) and Iron Oxide Nanocubes (IONCs) from 10 nm to 18 nm (FIG.1F – FIG.1I). All nanoparticle samples (spherical and cubic NPs) had uniform sizes with narrow size distributions, in which the standard deviation was controlled to be around 10% of the average size. The spherical and cubic shapes of nanoparticles were well controlled with uniform morphology. It could be said that the nanoparticles, in both spherical and cubic shapes, are of identical quality with narrow size distribution and uniform morphology. Thus, this is important for achieving accuracy in subsequent studies focusing on the effect of size and shape on magnetic properties and comparative studies between spherical and cubic shapes. [0073] FIG. 2A – FIG. 2B presents the XRD patterns of IONSs (FIG. 2A) and IONCs (FIG. 2B). Two major phases of iron oxide, including FeO and Fe₃O₄, were observed, which consistently agree with the results of previous work utilizing a similar synthesis method (Lak, A.; Cassani, M.; Mai, B. T.; Winckelmans, N.; Cabrera, D.; Sadrollahi, E.; Marras, S.; Remmer, H.; Fiorito, S.; Cremades-Jimeno, L.; Litterst, F. J.; Ludwig, F.; Manna, L.; Teran, F. J.; Bals, S.; Pellegrino, T. Fe²⁺ Deficiencies, FeO Subdomains, and Structural Defects Favor Magnetic Hyperthermia Performance of Iron Oxide Nanocubes into Intracellular Environment. Nano Lett. 2018, 18, 6856–6866; Lak, A.; Kraken, M.; Ludwig, F.; Kornowski, A.; Eberbeck, D.; Sievers, S.; J. Litterst, F.; Weller, H.; Schilling, M. Size Dependent Structural and Magnetic Properties of FeO– Fe₃O₄ Nanoparticles. Nanoscale 2013, 5, 12286–12295). The formation of the FeO phase in the core of the nanoparticles, followed by the Fe₃O₄ phase as the shell, was attributed to the fast growth ^{4913-4975-3383.1} Page 18 of 144 094876-000024WOPT rate of the nanoparticles, which then overwhelmed the oxidation rate of the FeO core. To grow larger NPs, a fast growth rate is preferred, leading to a more prominent existence of the FeO phase in the nanoparticles. It could be said that the larger the size of the NPs, both spherical and cubic shape, the more FeO phase was identified. The largest size of IONSs, approximately 28 nm, was prominently matched with the FeO phase, with the center position of peaks matching FeO crystal planes (111), (200), (220), and two minor peaks (311) and (222) were observable. Three regions in the XRD patterns were essential for analysis: 2θ from 33° to 38°, 2θ from 41° to 44°, and 2θ from 59° to 64° (Lak, A.; Niculaes, D.; Anyfantis, G. C.; Bertoni, G.; Barthel, M. J.; Marras, S.; Cassani, M.; Nitti, S.; Athanassiou, A.; Giannini, C.; Pellegrino, T. Facile Transformation of FeO/Fe₃O₄ Core-Shell Nanocubes to Fe₃O₄ via Magnetic Stimulation. Sci. Rep.2016, 6, 33295). In the first region, the diffraction peak of (111) in the FeO phase at 2θ = 36.2° was sandwiched between the diffraction peak of (311) at 35.5° and (222) at 37.2° of Fe₃O₄. The maxima of the diffraction peak were centered at 35.5° of (311) in the magnetite phase for IONSs size 9.8 nm and slightly shifted toward 2θ of 36.2° (FeO (111) planes) for larger particles. The maxima of the diffraction peak in this region were centered at 36.2° of FeO (111) for large sample sizes 21.8 nm and 28.3 nm of IONSs and 18 nm for IONCs. In the region from 41 to 44°, the maxima of the peak were centered at 43.2° for (400) planes in magnetite and shifted toward the lower diffraction angle at 42.0° of (200) in FeO. In the region from 61° to 63°, similar features were observed, in which the maxima peak of smaller nanoparticles (size 9.8 nm for IONSs and 11.8 nm for IONCs) was positioned at 62.7° and shifted toward the lower diffraction angle of 60.9° of (220) planes in FeO. [0074] From the TEM and XRD results, we can visualize the IONP system in this study as highly uniform iron oxide nanoparticles with tunable sizes and shapes. These exist as core-shell structures with FeO@Fe₃O₄ and have the tendency to contain more FeO phase at larger sizes. Larger particles, either spherical or cubic in shape, could have lower saturation magnetization due to the paramagnetic nature of FeO. The blocking temperature could shift toward higher temperatures for larger particles since the blocking temperature (T_B) is a size-dependent parameter (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Nanocrystals. Nat. Mater. 2004, 3, 891–895; Nozawa, R.; Naka, T.; Kurihara, M.; Togashi, T. Size-Tunable Synthesis of Iron Oxide Nanocrystals by Continuous Seed-Mediated Growth: Role of Alkylamine Species in the Stepwise Thermal Decomposition of Iron(II) Oxalate. Dalton Trans. 2021, 50, 16021–16029; Baaziz, W.; ^{4913-4975-3383.1} Page 19 of 144 094876-000024WOPT Pichon, B. P.; Fleutot, S.; Liu, Y.; Lefevre, C.; Greneche, J.-M.; Toumi, M.; Mhiri, T.; Begin-Colin, S. Magnetic Iron Oxide Nanoparticles: Reproducible Tuning of the Size and Nanosized-Dependent Composition, Defects, and Spin Canting. J. Phys. Chem. C 2014, 118, 3795–3810). However, this trend could not be guaranteed due to the existence of the FeO composition in each sample, which could shift the blocking temperature (T_B) depending on the amount of FeO composition in the entire particle structure (Wetterskog, E.; Tai, C.-W.; Grins, J.; Bergström, L.; Salazar-Alvarez, G. Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures: Topotaxial Oxidation of Fe_1-xO|Fe_3−δO₄ Core|Shell Nanocubes to Single-Phase Particles. ACS Nano 2013, 7, 7132–7144). [0075] Table 1. Magnetic Properties of Iron Oxide Nanospheres and Iron Oxide Nanocubes. Shape Size M_S T_B Estimated volume Equivalent Size^b ^{a c} K ^{d 3} e ^{4913-4975-3383.1} Page 20 of 144 094876-000024WOPT [0076] Table 1 presents the magnetic properties of IONPs of different sizes and shapes. For convenience in comparison, an equivalent size was calculated. For nanospheres, the equivalent size represents the edge length of nanocubes having a similar volume. Similarly, the equivalent size for nanocubes represents the diameter of nanospheres with a similar volume. Two trends can be delineated from the data: first, the blocking temperature (T_B) increases with the size of the particles, and second, the saturation magnetization (M_S) possibly decreases with the larger size of the particles. FIG.4A and FIG.4B presents the size versus M_S relation with a clear trend of M_S decreasing for larger nanoparticles. These results were understandable after interpreting the results of TEM and XRD analyses. The saturation magnetization of nanocubes seems to be higher than the M_S value of nanospheres. The data presented in Table 1 provides guidelines for selecting the NPs with desired SPM properties. [0077] From Table 1, we can compare iron oxide nanocubes with iron oxide nanospheres of comparable volumes. Three pairs of samples were compared: (1) 13.1 ± 1.0 nm (nanospheres) versus 10.2 ± 0.9 nm (nanocubes), (2) 15.6 ± 1.3 nm (nanospheres) versus 11.8 ± 1.3 nm (nanocubes), and (3) 21.8 ± 2.0 nm (nanospheres) versus 18.0 ± 1.4 nm (nanocubes). The M_S of nanocubes is clearly higher than the M_S value of nanospheres, which could be explained by the magnetic anisotropy factor of the cubic shape. Calculating the M_S (nanocubes)/M_S (nanospheres) ratio for the three pairs of samples (1), (2), (3), the ratios are 1.47, 1.27, and 1.14, respectively. This confirms the superior magnetic properties of iron oxide nanocubes over the iron oxide nanospheres. [0078] SPM properties of Superclusters. [0079] In various embodiments, the superclusters of the present invention were formed through the self-assembly of IONPs using oil droplets in micro-emulsion as templates to form the supercluster structures (Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self-Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). FIG.3B – FIG.3F presents the SEM images of superclusters fabricated from different sizes and shapes of nanoparticles. The size of the superclusters was calculated by generating a size distribution and is specified in the top right corner of the image, while the size of the nanoparticles is specified in the bottom right corner. In various embodiments, the superclusters of the present invention have round shapes with a broad size distribution, which could be explained by the diverse ^{4913-4975-3383.1} Page 21 of 144 094876-000024WOPT size distribution of droplets formed in the emulsion. Our synthesis results revealed that in some instances forming supercluster particles required a specific concentration of NP colloidal solution in chloroform with good dispersibility. From the examples studied, the larger the size of the nanoparticles, the higher the concentration of the colloidal solution required to form the superclusters, as specified in Table 2. [0080] Table 2. Magnetic Properties of Nanoparticles and their Superclusters. Structures Size At field 0.3 T At field 4 T T_B Shift of (nm) _{MS %} MS % increase (K) ^T _B [0081] Table 2 summarizes the magnetic properties of superclusters and their nanoparticles for comparison. First, the formation of superclusters significantly enhances saturation ^{4913-4975-3383.1} Page 22 of 144 094876-000024WOPT magnetization (M_S). The % increase in M_S when comparing the M_S of superclusters versus the M_S of their constituent nanoparticles is calculated for comparison. The enhancement of M_S in supercluster particles was notably prominent at low fields. This property is extremely useful for enhancing performance in sensing, MRI, and hyperthermia applications. Second, the formation of superclusters causes a shift in blocking temperature (T_B) to higher temperatures. The blocking temperature (T_B) indicates the temperature that separates SPM properties (T > T_B) from FM properties (T < T_B). The shift of T_B toward higher temperatures indicates stronger magnetic interactions among particles. However, the blocking temperature (T_B) effectively remains below 300 K, maintaining SPM properties. Surprisingly, supercluster particles in (FIG.3C, FIG.3E, FIG. 3F) have similar sizes ~ 240 nm; however, their blocking temperature (T_B) and saturation magnetization (M_S) are completely different. This demonstrates the concept of fine-tuning the SPM of supercluster particles by changing the sizes and shapes of their constituent nanoparticles. Similarly, different magnetic properties of supercluster size ~ 150 nm were observed for superclusters made by nanocubes size 10.2 nm and nanospheres size 13.1 nm. Therefore, by selecting the appropriate size and shape of the nanoparticles, the magnetic properties of superclusters, including saturation magnetization (M_S) and blocking temperature (T_B), can be finely tuned. [0082] Chapter 2 [0083] In various embodiments the present invention provides Fine-Tuning the Superparamagnetic Properties of FeO@Fe₃O₄ Core/Shell Nanoparticles and Superclusters by Controlling Size and Shape. [0084] Fine-tuning the superparamagnetic (SPM) properties of iron oxide core/shell nanoparticles (NPs), with precise control over size and shape, and their formation into superclusters, is crucial for advanced applications in biomedicine, biosensing, and electronic devices. We analyzed the size-dependent magnetic properties of FeO@Fe₃O₄ core/shell NPs in both spherical and cubic shapes prepared via the thermal decomposition of iron oleate. The analyses provided significant insights for designing and fabricating superclusters by assembling nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy analyses confirmed the presence of both FeO and Fe₃O₄ phases and the formation of the core/shell structure, with an increasing FeO/Fe₃O₄ phase ratio correlated with particle size. The SPM properties of these core/shell NPs ^{4913-4975-3383.1} Page 23 of 144 094876-000024WOPT were maintained, although saturation magnetization varied with size, shape, and FeO/Fe₃O₄ ratio. Notably, iron oxide nanocubes exhibited enhanced saturation magnetization due to improved crystallinity compared to their spherical counterparts. We introduced a unique strategy to enhance and fine-tune the SPM properties of FeO@Fe₃O₄ NPs by assembling them into supercluster particles. Magnetometry measurements indicated that supercluster formation promotes interparticle interactions and enhances magnetic properties. By controlling the size and shape of the individual nanoparticles, we demonstrated the creation of SPM superclusters of consistent sizes, including the 150 nm and 240 nm superclusters reported here. This study demonstrates the pivotal role of individual nanoparticles in fine-tuning the SPM properties of superclusters. Our research presents a synthetic strategy for optimizing the SPM properties of iron oxide core/shell NPs and their superclusters across a wide range of magnetically driven applications. [0085] Magnetic iron oxide nanoparticles (IONPs) possessing superparamagnetic (SPM) properties and exceptional biocompatibility offer enormous potential in advanced biomedical applications, including magnetic resonance imaging (MRI), drug delivery, magnetic hyperthermia, and biosensing (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci. 2021, 11, 11301; Tran, H.-V.; Ngo, N. M.; Medhi, R.; Srinoi, P.; Liu, T.; Rittikulsittichai, S.; Lee, T. R. Multifunctional Iron Oxide Magnetic Nanoparticles for Biomedical Applications: A Review. Materials 2022, 15, 503). The utility of SPM properties lies in their ability to be manipulated and the capability to switch on and off under a magnetic field. In contrast to ferrimagnetic (FiM) or ferromagnetic (FM) properties, SPM properties excel in minimizing interparticle interactions, thereby reducing particle aggregation. This feature enhances the dispersibility of nanoparticles (NPs) in colloidal solutions and facilitates their redispersion after magnetic separation. Consequently, tailoring the magnetic properties of IONPs by controlling their structure emerges as a crucial strategy for understanding nano-magnetism and optimizing NPs for specific biomedical applications (Gavilán, H.; Kumar Avugadda, S.; Fernández-Cabada, T.; Soni, N.; Cassani, M.; T. Mai, B.; Chantrell, R.; Pellegrino, T. Magnetic Nanoparticles and Clusters for Magnetic Hyperthermia: Optimizing Their Heat Performance and Developing Combinatorial Therapies to Tackle Cancer. Chem. Soc. Rev. 2021, 50, 11614–11667; Gavilán, H.; Posth, O.; Bogart, L. K.; Steinhoff, U.; Gutiérrez, L.; Morales, M. P. How Shape and Internal Structure Affect the Magnetic Properties of Anisometric Magnetite Nanoparticles. Acta Mater.2017, 125, 416–424). ^{4913-4975-3383.1} Page 24 of 144 094876-000024WOPT [0086] Typically, IONPs with SPM properties are single-domain particles with sizes smaller than 25 nm (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci.2021, 11, 11301; Kolhatkar, A. G.; Jamison, A. C.; Litvinov, D.; Willson, R. C.; Lee, T. R. Tuning the Magnetic Properties of Nanoparticles. Int. J. Mol. Sci. 2013, 14, 15977–16009). Although the transition size from superparamagnetic (SPM) to ferromagnetic (FM) behavior is generally considered to be around 25 nm, this size can vary depending on the shapes (e.g., spheres, cubes, rods, etc.) and compositions of the NPs (Fe₃O₄, FeO, γ-Fe₂O₃, α-Fe₂O₃). Additionally, SPM properties can be observed in larger IONPs, above 100 nm, if these particles are secondary structures formed through the stacking of single-domain-size crystals in polycrystalline particles (Xuan, S.; Wang, Y.-X. J.; Yu, J. C.; Cham-Fai Leung, K. Tuning the Grain Size and Particle Size of Superparamagnetic Fe₃O₄ Microparticles. Chem. Mater.2009, 21, 5079–5087; Ge, J.; Hu, Y.; Biasini, M.; Beyermann, W. P.; Yin, Y. Superparamagnetic Magnetite Colloidal Nanocrystal Clusters. Angew. Chem. Int. Ed. 2007, 46, 4342–4345; Nguyen, M. D.; Deng, L.; Lee, J. M.; Mariel, K.; Fuller, M.; Hoijang, S.; Robles Hernandez, F. C.; Chu, C.-W.; Litvinov, D.; Hadjiev, V. G.; Xu, S.; Phan, M.-H.; Lee, T. R. Magnetic Tunability via Control of Crystallinity and Size in Polycrystalline Iron Oxide Nanoparticles. Small 2024, 20, 2402940) or through the assembly of SPM IONPs (Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc.2007, 129, 14166–14167; Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc. 2018, 140, 15038–15047; Wang, T.; Wang, X.; LaMontagne, D.; Wang, Z.; Wang, Z.; Cao, Y. C. Shape-Controlled Synthesis of Colloidal Superparticles from Nanocubes. J. Am. Chem. Soc.2012, 134, 18225–18228). Indeed, large-size SPM IONPs (size > 100 nm) have been reported from polycrystalline NPs with small crystallite sizes, (Xuan, S.; Wang, Y.-X. J.; Yu, J. C.; Cham-Fai Leung, K. Tuning the Grain Size and Particle Size of Superparamagnetic Fe₃O₄ Microparticles. Chem. Mater.2009, 21, 5079–5087; Ganesan, V.; Lahiri, B. B.; Louis, C.; Philip, J.; Damodaran, S. P. Size-Controlled Synthesis of Superparamagnetic Magnetite Nanoclusters for Heat Generation in an Alternating Magnetic Field. J. Mol. Liq. 2019, 281, 315–323) and from superclusters of single-domain IONP assemblies, (Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc.2007, 129, 14166– ^{4913-4975-3383.1} Page 25 of 144 094876-000024WOPT 14167; Wang, T.; Wang, X.; LaMontagne, D.; Wang, Z.; Wang, Z.; Cao, Y. C. Shape-Controlled Synthesis of Colloidal Superparticles from Nanocubes. J. Am. Chem. Soc. 2012, 134, 18225– 18228; Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256) or from clusters of single-domain SPM IONPs encapsulated in a polymer matrix or an inorganic shell (Yoon, T.-J.; Lee, H.; Shao, H.; Hilderbrand, S. A.; Weissleder, R. Multicore Assemblies Potentiate Magnetic Properties of Biomagnetic Nanoparticles. Adv. Mater. 2011, 23, 4793–4797). Among these three types of large-size SPM IONPs, supercluster particles (assemblies of single-domain IONPs) offer flexibility in manipulating particle structures compared to polycrystalline particles, while minimizing the non-magnetic component, unlike the encapsulated particles. Consequently, tuning the size, shape, and compositions of individual nanoparticles is key to forming unique supercluster structures with desirable properties for advanced biomedical applications. [0087] While maintaining the benefits of SPM properties, large-size SPM IONPs offer advantages such as stronger saturation magnetization through the collective close interactions of component SPM nanoparticles, facilitating efficient magnetic separation (Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc.2018, 140, 15038–15047; Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self- Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). This advantage holds immense potential for biomedical applications, positioning large-size SPM IONPs as a viable alternative to smaller SPM IONPs with sizes less than 30 nm. Despite the extensive use of SPM IONPs in biomedicine, concerns about toxicity persist due to their small size, which may lead to deep penetration and retention in sensitive areas of the body (D, R.; Rao, P. Nanoparticles: Is Toxicity a Concern? EJIFCC 2011, 22, 92–101; Moura, R. P.; Almeida, A.; Sarmento, B. The Role of Non- Endothelial Cells on the Penetration of Nanoparticles through the Blood Brain Barrier. Progress in Neurobiology 2017, 159, 39–49; Kefeni, K. K.; Msagati, T. A. M.; Nkambule, T. TI.; Mamba, B. B. Spinel Ferrite Nanoparticles and Nanocomposites for Biomedical Applications and Their Toxicity. Mater. Sci. Eng. C 2020, 107, 110314). Therefore, utilizing large SPM IONPs with ^{4913-4975-3383.1} Page 26 of 144 094876-000024WOPT improved magnetic properties, such as enhanced saturation magnetization, presents an alternative approach with significant potential in biomedicine, deserving of more attention and further exploration. Dynabead M280 SPM particles, with a size of 2.8 μm (clusters of SPM IONPs dispersed in a polymer matrix), are a prominent example of such large SPM particles useful in bio- detection and bio-purification (Chen, Y.-T.; Medhi, R.; Nekrashevich, I.; Litvinov, D.; Xu, S.; Lee, T. R. Specific Detection of Proteins Using Exceptionally Responsive Magnetic Particles. Anal. Chem. 2018, 90, 6749–6756; Chen, Y.-T.; Kolhatkar, A. G.; Zenasni, O.; Xu, S.; Lee, T. R. Biosensing Using Magnetic Particle Detection Techniques. Sensors 2017, 17, 2300). Recent studies have demonstrated the high efficiency of large SPM IONPs as magnetic agents in biosensing and MRI (Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256; Wu, C.; Xu, Y.; Yang, L.; Wu, J.; Zhu, W.; Li, D.; Cheng, Z.; Xia, C.; Guo, Y.; Gong, Q.; Song, B.; Ai, H. Negatively Charged Magnetite Nanoparticle Clusters as Efficient MRI Probes for Dendritic Cell Labeling and In Vivo Tracking. Adv. Funct. Mater.2015, 25, 3581– 3591; Cai, Z.; Wu, C.; Yang, L.; Wang, D.; Ai, H. Assembly-Controlled Magnetic Nanoparticle Clusters as MRI Contrast Agents. ACS Biomater. Sci. Eng.2020, 6, 2533–2542). Interestingly, the Pellegrino group reported the improved hyperthermia properties of clusters comprising small iron oxide nanocubes (Niculaes, D.; Lak, A.; Anyfantis, G. C.; Marras, S.; Laslett, O.; Avugadda, S. K.; Cassani, M.; Serantes, D.; Hovorka, O.; Chantrell, R.; Pellegrino, T. Asymmetric Assembling of Iron Oxide Nanocubes for Improving Magnetic Hyperthermia Performance. ACS Nano 2017, 11, 12121–12133). Our recent study has also revealed the large magnetic hyperthermia responses of large polycrystalline IONPs, with sizes ranging from 160 to 400 nm at a small dose of 0.5 mg/mL (Attanayake, S. B.; Nguyen, M. D.; Chanda, A.; Alonso, J.; Orue, I.; Lee, T. R.; Srikanth, H.; Phan, M.-H. Superparamagnetic Superparticles for Magnetic Hyperthermia Therapy: Overcoming the Particle Size Limit.2024, (submitted)). [0088] To date, two methods have been developed for producing SPM IONPs with tunable sizes and shapes: the thermal decomposition of iron(III) acetylacetonate in benzyl ether, and the thermal decomposition of iron(III) oleate in non-polar solvents (hexadecane, octadecene, tetradecane, docosane) (Kim, D.; Lee, N.; Park, M.; Kim, B. H.; An, K.; Hyeon, T. Synthesis of Uniform Ferrimagnetic Magnetite Nanocubes. J. Am. Chem. Soc. 2009, 131, 454–455; Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra- ^{4913-4975-3383.1} Page 27 of 144 094876-000024WOPT Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater. 2004, 3, 891–895; Muro- Cruces, J.; Roca, A. G.; López-Ortega, A.; Fantechi, E.; del-Pozo-Bueno, D.; Estradé, S.; Peiró, F.; Sepúlveda, B.; Pineider, F.; Sangregorio, C.; Nogues, J. Precise Size Control of the Growth of Fe₃O₄ Nanocubes over a Wide Size Range Using a Rationally Designed One-Pot Synthesis. ACS Nano 2019, 13, 7716–7728; Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core–Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater. 2023, 35, 6201– 6219). The former method offers advantages in producing a highly pure Fe₃O₄ phase but faces challenges due to the instability of benzyl ether at high temperatures, which negatively impacts reproducibility and scalability (Muro-Cruces, J.; Roca, A. G.; López-Ortega, A.; Fantechi, E.; del- Pozo-Bueno, D.; Estradé, S.; Peiró, F.; Sepúlveda, B.; Pineider, F.; Sangregorio, C.; Nogues, J. Precise Size Control of the Growth of Fe₃O₄ Nanocubes over a Wide Size Range Using a Rationally Designed One-Pot Synthesis. ACS Nano 2019, 13, 7716–7728; Qiao, L.; Fu, Z.; Li, J.; Ghosen, J.; Zeng, M.; Stebbins, J.; Prasad, P. N.; Swihart, M. T. Standardizing Size- and Shape- Controlled Synthesis of Monodisperse Magnetite (Fe₃O₄) Nanocrystals by Identifying and Exploiting Effects of Organic Impurities. ACS Nano 2017, 11, 6370–6381). On the other hand, the thermal decomposition of iron(III) oleate tends to form the antiferromagnetic (AFM) FeO phase within the core of Fe₃O₄ particles; however, its higher reproducibility makes it more suitable for larger-scale synthesis of particles (Estrader, M.; López-Ortega, A.; V. Golosovsky, I.; Estradé, S.; G. Roca, A.; Salazar-Alvarez, G.; López-Conesa, L.; Tobia, D.; Winkler, E.; D. Ardisson, J.; A. Macedo, W. A.; Morphis, A.; Vasilakaki, M.; N. Trohidou, K.; Gukasov, A.; Mirebeau, I.; L. Makarova, O.; D. Zysler, R.; Peiró, F.; Dolors Baró, M.; Bergström, L.; Nogués, J. Origin of the Large Dispersion of Magnetic Properties in Nanostructured Oxides: Fe_xO/Fe₃O₄ Nanoparticles as a Case Study. Nanoscale 2015, 7, 3002–3015; Wetterskog, E.; Tai, C.-W.; Grins, J.; Bergström, L.; Salazar-Alvarez, G. Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures: Topotaxial Oxidation of Fe_1-xO|Fe_3−δO₄ Core|Shell Nanocubes to Single-Phase Particles. ACS Nano 2013, 7, 7132–7144; Feld, A.; Weimer, A.; Kornowski, A.; Winckelmans, N.; Merkl, J.-P.; Kloust, H.; Zierold, R.; Schmidtke, C.; Schotten, T.; Riedner, M.; Bals, S.; Weller, H. Chemistry of Shape-Controlled Iron Oxide Nanocrystal Formation. ACS Nano 2019, 13, 152– 162). Due to its AFM nature, the presence of the FeO phase usually reduces the overall saturation ^{4913-4975-3383.1} Page 28 of 144 094876-000024WOPT magnetization of the system; however, magnetic coupling with the FiM Fe₃O₄ phase can enhance magnetic anisotropy, rendering it useful for specific biomedical applications. The exchange coupling between the AFM FeO core and the FiM Fe₃O₄ shell has been shown to improve magnetic anisotropy, leading to enhanced magnetic hyperthermia responses in FeO@Fe₃O₄ core/shell NPs (Khurshid, H.; Alonso, J.; Nemati, Z.; Phan, M. H.; Mukherjee, P.; Fdez-Gubieda, M. L.; Barandiarán, J. M.; Srikanth, H. Anisotropy Effects in Magnetic Hyperthermia: A Comparison between Spherical and Cubic Exchange-Coupled FeO/Fe₃O₄ Nanoparticles. J. Appl. Phys.2015, 117, 17A337; Lee, J.-H.; Jang, J.; Choi, J.; Moon, S. H.; Noh, S.; Kim, J.; Kim, J.-G.; Kim, I.-S.; Park, K. I.; Cheon, J. Exchange-Coupled Magnetic Nanoparticles for Efficient Heat Induction. Nat. Nanotechnol. 2011, 6, 418–422). However, the effect of varying FeO/Fe₃O₄ ratio on the magnetic and hyperthermia properties of the FeO@Fe₃O₄ core/shell system has, to the best of our knowledge, not been studied. From a different perspective, the exchange-coupled FeO@Fe₃O₄ core/shell systems have also been reported to exhibit an exchange-bias (EB) phenomenon, making them attractive for applications in spintronics and magnetic recording (Pichon, B. P.; Gerber, O.; Lefevre, C.; Florea, I.; Fleutot, S.; Baaziz, W.; Pauly, M.; Ohlmann, M.; Ulhaq, C.; Ersen, O.; Pierron-Bohnes, V.; Panissod, P.; Drillon, M.; Begin-Colin, S. Microstructural and Magnetic Investigations of Wüstite-Spinel Core-Shell Cubic-Shaped Nanoparticles. Chem. Mater.2011, 23, 2886–2900; Phan, M.-H.; Alonso, J.; Khurshid, H.; Lampen-Kelley, P.; Chandra, S.; Stojak Repa, K.; Nemati, Z.; Das, R.; Iglesias, Ó.; Srikanth, H. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems. Nanomaterials 2016, 6, 221). These observations have led us to propose employing the thermal decomposition of iron oleates as a method to produce core/shell IONPs with tunable sizes and shapes, followed by the formation of supercluster structures from these NPs. A clear understanding of the structure-property (magnetism) relationship in these nanosystems will help in tuning the SPM properties for diverse applications. [0089] In the work reported herein, we synthesized iron oxide nanospheres and iron oxide nanocubes through the thermal decomposition of iron oleate, enabling tunable sizes for a comprehensive study of magnetic properties. The composition of these NP systems included FeO@Fe₃O₄ core/shell structures, with larger particles tending to exhibit a more pronounced FeO phase. Two important parameters -- saturation magnetization (M_S) and blocking temperature (T_B) -- for different sizes of nanospheres and nanocubes were investigated for comparison. Experimental data revealed stronger saturation magnetization in the iron oxide nanocubes and ^{4913-4975-3383.1} Page 29 of 144 094876-000024WOPT provided guidance on selecting IONPs with desirable SPM properties. To further fine-tune the SPM properties, superclusters were fabricated using these selected IONPs (both iron oxide nanospheres and nanocubes) of various sizes and shapes. A systematic analysis of the magnetic properties of the resulting supercluster particles, relative to their individual IONPs, shows a significant improvement in saturation magnetization (M_S) and a shift in the blocking temperature (T_B) toward higher temperatures. We attributed these enhanced magnetic properties to enhanced magnetic interactions among the individual IONPs that formed the superclusters, desirable for advanced biomedical applications. Surprisingly, the magnetic properties of superclusters of similar sizes can be tuned by varying the size, shape and FeO/Fe₃O₄ ratio of their constituent nanoparticles. This finding underscores the great potential for fine-tuning the SPM properties of core/shell IONPs and their supercluster structures. [0090] Structural and Magnetic Characterization of Iron Oxide Nanoparticles. [0091] The structure and magnetic properties of iron oxide nanoparticles (IONPs) with cubic and spherical shapes were studied by characterizing the nanoparticles (NPs) using transmission electron microscopy (TEM), X-ray diffractometry (XRD), and superconducting quantum interference device (SQUID) measurements. In the context of this paper, the size of particles is defined as the diameter for spherical shapes and edge length for cubic shapes. FIG.1A – FIG. 1I presents TEM images of iron oxide nanospheres (IONSs) with average sizes ranging from 10 nm to 28 nm (FIG.1A – FIG.1E) and iron oxide nanocubes (IONCs) from 10 nm to 18 nm (FIG.1F – FIG. 1I). All NP samples, both spherical and cubic, exhibited uniform sizes with narrow size distributions, where the standard deviation was controlled to be around 10% of the average size. The morphology of both the spherical and cubic NPs was uniformly controlled. Therefore, it is reasonable to assert that the synthesized NPs, whether spherical or cubic, are of identical quality with narrow size distributions and uniform morphologies. This uniformity enables subsequent studies focusing on the effects of size and shape on the magnetic properties of IONPs. [0092] FIG. 2A presents the XRD patterns of IONSs and FIG. 2B presents the XRD patterns of IONCs (FIG. 2B). Two major phases of iron oxide, FeO and Fe₃O₄, were observed, consistent with results from previous studies using a similar synthesis method (Lak, A.; Cassani, M.; Mai, B. T.; Winckelmans, N.; Cabrera, D.; Sadrollahi, E.; Marras, S.; Remmer, H.; Fiorito, S.; Cremades-Jimeno, L.; Litterst, F. J.; Ludwig, F.; Manna, L.; Teran, F. J.; Bals, S.; Pellegrino, T. Fe²⁺ Deficiencies, FeO Subdomains, and Structural Defects Favor Magnetic Hyperthermia ^{4913-4975-3383.1} Page 30 of 144 094876-000024WOPT Performance of Iron Oxide Nanocubes into Intracellular Environment. Nano Lett.2018, 18, 6856– 6866; Lak, A.; Kraken, M.; Ludwig, F.; Kornowski, A.; Eberbeck, D.; Sievers, S.; J. Litterst, F.; Weller, H.; Schilling, M. Size Dependent Structural and Magnetic Properties of FeO–Fe₃O₄ Nanoparticles. Nanoscale 2013, 5, 12286–12295). The formation of the FeO phase at the core of particles, followed by the Fe₃O₄ phase as the shell, was attributed to the fast growth rate of the nanoparticles, which overwhelmed the oxidation rate of the FeO core (Cotin, G.; Perton, F.; Petit, C.; Sall, S.; Kiefer, C.; Begin, V.; Pichon, B.; Lefevre, C.; Mertz, D.; Greneche, J.-M.; Begin- Colin, S. Harnessing Composition of Iron Oxide Nanoparticle: Impact of Solvent-Mediated Ligand–Ligand Interaction and Competition between Oxidation and Growth Kinetics. Chem. Mater.2020, 32, 9245–9259). To grow larger NPs, a fast growth rate is preferred, leading to a more pronounced formation of the FeO phase. Notably, the larger the size of the NPs, whether spherical or cubic, the more the FeO phase was identified. The largest IONSs, approximately 28 nm in size, prominently matched with the FeO phase, with the center position of peaks corresponding to FeO crystal planes (111), (200), (220), and two minor peaks at (311) and (222) being observable. Three regions in the XRD patterns were crucial for analysis: 2θ from 33° to 38°, 2θ from 41° to 44°, and 2θ from 59° to 64° (Lak, A.; Niculaes, D.; Anyfantis, G. C.; Bertoni, G.; Barthel, M. J.; Marras, S.; Cassani, M.; Nitti, S.; Athanassiou, A.; Giannini, C.; Pellegrino, T. Facile Transformation of FeO/Fe₃O₄ Core-Shell Nanocubes to Fe₃O₄ via Magnetic Stimulation. Sci. Rep.2016, 6, 33295). In the first region, the diffraction peak of (111) in the FeO phase at 2θ = 36.2° was flanked by the diffraction peaks of (311) at 35.5° and (222) at 37.2° from Fe₃O₄. The maxima of the diffraction peaks were centered at 35.5° of (311) in the magnetite phase for IONSs size 9.8 nm and shifted toward 2θ = 36.2° (FeO (111) planes) for larger particles. For sample sizes of 21.8 nm and 28.3 nm for IONSs and 18 nm for IONCs, the maxima in this region were centered at 36.2° for FeO (111). In the region from 41° to 44°, the maxima of the peaks were centered at 43.2° for the (400) planes in magnetite and shifted toward the lower diffraction angle at 42.0° for (200) in FeO. In the region from 61° to 63°, similar trends were observed, where the peak maxima for smaller particles (size 9.8 nm for IONSs and 11.8 nm for IONCs) were positioned at 62.7° and shifted toward the lower diffraction angle of 60.9° for (220) planes in FeO. [0093] From the analysis of the XRD results, we observed an increase in the size of IONPs with a higher ratio of the FeO phase, which impacts the saturation magnetization of the NPs. The (200) peak of FeO is the most prominent, with the highest peak intensity observed in the largest ^{4913-4975-3383.1} Page 31 of 144 094876-000024WOPT nanospheres (size 28.3 nm) and nanocubes (size 18 nm). By deconvoluting the (200) peak of FeO at around 42.0° and the (400) peak of Fe₃O₄ at 43.2°, the crystallite size of FeO could be estimated, (Tancredi, P.; Rivas Rojas, P. C.; Moscoso-Londoño, O.; Wolff, U.; Neu, V.; Damm, C.; Rellinghaus, B.; Knobel, M.; M. Socolovsky, L. Synthesis Process, Size and Composition Effects of Spherical Fe₃O₄ and FeO@Fe₃O₄ Core/Shell Nanoparticles. New J. Chem. 2017, 41, 15033– 15041; Lak, A.; Niculaes, D.; Anyfantis, G. C.; Bertoni, G.; Barthel, M. J.; Marras, S.; Cassani, M.; Nitti, S.; Athanassiou, A.; Giannini, C.; Pellegrino, T. Facile Transformation of FeO/Fe₃O₄ Core-Shell Nanocubes to Fe₃O₄ via Magnetic Stimulation. Sci. Rep.2016, 6, 33295) as shown in Table 3. Due to the insignificant amount of the FeO phase in smaller NPs, the crystallite size of the FeO phase in samples sized 9.8 nm (nanospheres), 10.2 nm (nanocubes), and 11.8 nm (nanocubes) could not be determined from XRD deconvolution. The peak positions of these samples mostly coincide with the (400) of the Fe₃O₄ phase; therefore, the crystallite size of Fe₃O₄ along (400) was calculated. The calculated Fe₃O₄ crystallite size closely matches the size of the NPs. Combining the features of XRD patterns with the shift of peak maxima at three regions (2θ from 33° to 38°, 2θ from 41° to 44°, and 2θ from 59° to 64°), as discussed above, and the estimated crystallite sizes specified in Table 3, it is apparent that larger FeO@Fe₃O₄ core-shell NPs could possess a larger volume fraction of the FeO phase in the core/shell structure. It is reasonable to assume that larger particles, spherical or cubic in shape, would have lower saturation magnetization due to the antiferromagnetic nature of FeO. It is also reasonable to assume that the blocking temperature (T_B) will shift toward higher temperatures for larger single-phase Fe₃O₄ particles, since T_B is a size-dependent parameter (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater.2004, 3, 891–895; Nozawa, R.; Naka, T.; Kurihara, M.; Togashi, T. Size-Tunable Synthesis of Iron Oxide Nanocrystals by Continuous Seed-Mediated Growth: Role of Alkylamine Species in the Stepwise Thermal Decomposition of Iron(II) Oxalate. Dalton Trans.2021, 50, 16021–16029; Baaziz, W.; Pichon, B. P.; Fleutot, S.; Liu, Y.; Lefevre, C.; Greneche, J.-M.; Toumi, M.; Mhiri, T.; Begin-Colin, S. Magnetic Iron Oxide Nanoparticles: Reproducible Tuning of the Size and Nanosized-Dependent Composition, Defects, and Spin Canting. J. Phys. Chem. C 2014, 118, 3795–3810). However, this trend might not occur in biphasic systems like our FeO@Fe₃O₄ core/shell NPs. Changes in T_B are not solely driven by changes in the size and shape of NPs, but also by the FeO/Fe₃O₄ ratio in the entire nanoparticle structure ^{4913-4975-3383.1} Page 32 of 144 094876-000024WOPT (Wetterskog, E.; Tai, C.-W.; Grins, J.; Bergström, L.; Salazar-Alvarez, G. Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures: Topotaxial Oxidation of Fe_1- _xO|Fe_3−δO₄ Core|Shell Nanocubes to Single-Phase Particles. ACS Nano 2013, 7, 7132–7144). [0094] Table 3. Crystallite Sizes of FeO (200) and Fe3O4 (400) Determined by XRD. Particle Shape Particle Size (nm) Crystallite Size Crystallite Size (nm) (nm) Fe3O4 (400) [0095] Two samples of the largest size, nanospheres (size 28.3 nm) and nanocubes (size 18.0 nm), were further characterized using atomic resolution TEM, and the FFT were simulated for crystallographic analysis. From FIG.9A – FIG.9G, core-shell structures were observed, with the FeO size closely matching the calculated crystallite size values in Table 3. FFT diffraction patterns confirmed the existence of FeO as the core, with visible (111) and (200) planes, and Fe₃O₄ as the shell, with visible (220), (311), (222), and (400) planes. As indicated in the XRD results, the FeO phase is more dominant in the larger nanoparticles. Therefore, the smallest sample, nanospheres with average size 9.8 nm, was further characterized. High-resolution TEM and FFT of the nanospheres (size 9.8 nm), shown in FIG. 13, revealed no core-shell structures, with the entire particle indexed to the magnetite phase, showing observable (220) and (311) planes of Fe₃O₄. The atomic-resolution TEM and FFT results are consistent with the analysis from the XRD results. ^{4913-4975-3383.1} Page 33 of 144 094876-000024WOPT [0096] The XRD patterns can be used to index and identify the presence of different iron oxide phases, such as FeO, Fe₃O₄, and α-Fe₂O₃ (hematite). However, Fe₃O₄ and ɣ-Fe₂O₃ are indistinguishable in XRD patterns due to their similar cubic crystal structures (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci.2021, 11, 11301; Phan, M.-H.; Alonso, J.; Khurshid, H.; Lampen-Kelley, P.; Chandra, S.; Stojak Repa, K.; Nemati, Z.; Das, R.; Iglesias, Ó.; Srikanth, H. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems. Nanomaterials 2016, 6, 221). Consequently, the shell composition could be Fe₃O₄, ɣ-Fe₂O₃, or a mixture of these two phases. XPS, with its surface sensitivity, was used to further confirm the composition of the shells. FIG.10A – FIG.10B shows the high-resolution XPS spectra of Fe 2p, which confirm the presence of a pure Fe₃O₄ phase without any evidence of ɣ-Fe₂O₃ coexistence (Anderson, J. F.; Kuhn, M.; Diebold, U. Epitaxially Grown Fe₃O₄ Thin Films: An XPS Study. Surf. Sci. Spectra 1996, 4, 266–272). The absence of a satellite peak around 718 eV indicates the absence of ɣ-Fe₂O₃ (Mansour, A. N.; Brizzolara, R. A. Characterization of the Surface of γ-Fe₂O₃ Powder by XPS. Surf. Sci. Spectra 1996, 4, 351–356; Ibrahim Dar, M.; A. Shivashankar, S. Single Crystalline Magnetite, Maghemite, and Hematite Nanoparticles with Rich Coercivity. RSC Adv. 2014, 4, 4105–4113). Therefore, the data from surface-sensitive technique like XPS can conclude the pure Fe₃O₄ phase of the nanoparticle shell. To further confirm the phase composition of nanoparticles, analysis using Raman spectroscopy was conducted with more details on the phase composition in bulk scale. All distinct peaks of Fe₃O₄ phase, especially two major peaks at around 670 cm^-1 and 540 cm^-1, were observed, indicating the highly pure Fe₃O₄ phase in nanoparticles (Chamritski, I.; Burns, G. Infrared- and Raman-Active Phonons of Magnetite, Maghemite, and Hematite: A Computer Simulation and Spectroscopic Study. J. Phys. Chem. B 2005, 109, 4965– 4968; Hanesch, M. Raman Spectroscopy of Iron Oxides and (Oxy)Hydroxides at Low Laser Power and Possible Applications in Environmental Magnetic Studies. Geophys. J. Int. 2009, 177, 941– 948). For the FeO phase, FeO crystallizes as rock-salt structure in the Fm-3m space group, which is thought to be a weak Raman scatterer without proper Raman active modes (Hanesch, M. Raman Spectroscopy of Iron Oxides and (Oxy)Hydroxides at Low Laser Power and Possible Applications in Environmental Magnetic Studies. Geophys. J. Int. 2009, 177, 941–948; Testa-Anta, M.; Rodríguez-González, B.; Salgueiriño, V. Partial FeO–Fe₃O₄ Phase Transition Along the <111> ^{4913-4975-3383.1} Page 34 of 144 094876-000024WOPT Direction of the Cubic Crystalline Structure in Iron Oxide Nanocrystals. Part. Part. Syst. Charact. 2019, 36, 1900283). [0097] Table 4. Magnetic Properties of Iron Oxide Nanospheres and Iron Oxide Nanocubes. Particle Particle Size M_S T_B (K) Estimated Equivalent Size Shape (nm) (emu/ ) Volume (nm³) (nm) [0098] The detailed field dependence of magnetization (M(H)) and temperature dependence of magnetization (M(T)) data of IONPs are presented in FIG. 14A – FIG. 14F and FIG.15A – FIG.15E. Table 4 summarizes the magnetic parameters deduced from these data for IONPs of different sizes and shapes. For comparison, an equivalent size was calculated as described in the following sentences. For nanospheres, the equivalent size represents the edge length of nanocubes with a similar volume. Similarly, the equivalent size for nanocubes represents the diameter of nanospheres with a similar volume. The shape of the M-H curves presented in FIG. 14A and FIG.15A indicates the need for a high magnetic field to saturate the magnetic moment of ^{4913-4975-3383.1} Page 35 of 144 094876-000024WOPT NPs due to the presence of the AFM FeO core (Testa-Anta, M.; Rodríguez-González, B.; Salgueiriño, V. Partial FeO–Fe₃O₄ Phase Transition Along the <111> Direction of the Cubic Crystalline Structure in Iron Oxide Nanocrystals. Part. Part. Syst. Charact. 2019, 36, 1900283; Baaziz, W.; P. Pichon, B.; Grenèche, J.-M.; Begin-Colin, S. Effect of Reaction Environment and in Situ Formation of the Precursor on the Composition and Shape of Iron Oxide Nanoparticles Synthesized by the Thermal Decomposition Method. CrystEngComm 2018, 20, 7206–7220). Two trends can be drawn from our magnetic data: first, the T_B increases with the size of the particles; second, the saturation magnetization (M_S) appears to decrease in particles with larger sizes. FIG. 4A – FIG. 4B presents the M_S versus size relation, showing a trend of M_S decreasing for larger particles. This reduction might be due to the AFM enhancement of the FeO core at the expense of the FiM Fe₃O₄ shell, thus reducing the total magnetic moment in larger particles. The M_S values of IONCs appear to be higher than those of IONSs, probably due to the enhanced crystallinity in the former. The data in Table 4 provide good guidance on selecting NPs with desired SPM properties for biomedical applications and for forming their supercluster structures. The reduction in M_S due to an increasing volume of the FeO phase, as estimated in Table 3, illustrates the relationship between the M_S and particle size in these core/shell IONPs. [0099] From Table 4, we can compare the properties of IONCs with IONSs of comparable volumes. Three pairs of samples were compared: (a) 13.1 ± 1.0 nm (nanospheres) versus 10.2 ± 0.9 nm (nanocubes), (b) 15.6 ± 1.3 nm (nanospheres) versus 11.8 ± 1.3 nm (nanocubes), and (c) 21.8 ± 2.0 nm (nanospheres) versus 18.0 ± 1.4 nm (nanocubes). The comparisons show that the M_S values of IONCs are higher than those of IONSs, largely due to the dominance of the FiM Fe₃O₄ phase compared to the AFM FeO phase in the former (see Table 3). Calculating the M_S (nanocubes)/M_S (nanospheres) ratio for the three pairs of samples, the ratios are 1.47, 1.27, and 1.14, respectively. This analysis confirms the superior magnetic properties of core/shell IONCs compared to their IONS counterparts for biomedical applications. [0100] The superclusters were formed through the self-assembly of IONPs, using oil droplets in a microemulsion as templates to form the supercluster structures (Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self- Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). FIG. 11A – FIG. 11F presents SEM images of superclusters fabricated from individual nanoparticles of various sizes and shapes. The ^{4913-4975-3383.1} Page 36 of 144 094876-000024WOPT superclusters have rounded shapes with a broad size distribution, which can be attributed to the diverse size distribution of droplets formed in the emulsion. Our synthesis results showed that in some instances forming supercluster particles requires a specific concentration of NP colloidal solution in chloroform with good dispersibility. From the examples studied, the larger the size of the individual nanoparticles, the higher the concentration of colloidal solution needed to form the superclusters, as specified in Table 2. [0101] Table 5. Magnetic Properties of Nanoparticles and Their Corresponding Superclusters. Structures Size Magnetic Field (0.3 T) Magnetic Field (4 T) TB Shift (nm) M % M % (K) of TB ^{4913-4975-3383.1} Page 37 of 144 094876-000024WOPT Nanocubes 11.8 ± 50.8 65.6 252 1.3 rs ers are presented in FIG.16A – FIG.16D and FIG.17A – FIG.17F. Table 5 summarizes the magnetic parameters deduced from these data for the superclusters and their constituent nanoparticles. The data show that the formation of superclusters significantly enhances the M_S values compared to those of their constituent nanoparticles. The enhancement of magnetization in the supercluster particles relative to their individual IONPs is unexpected, especially at low fields (FIG.16A – FIG. 16D and FIG. 17A – FIG. 17F). This property is extremely useful for enhancing magnetic biosensing, MRI contrast, and hyperthermia efficiency (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci. 2021, 11, 11301; Gavilán, H.; Kumar Avugadda, S.; Fernández-Cabada, T.; Soni, N.; Cassani, M.; T. Mai, B.; Chantrell, R.; Pellegrino, T. Magnetic Nanoparticles and Clusters for Magnetic Hyperthermia: Optimizing Their Heat Performance and Developing Combinatorial Therapies to Tackle Cancer. Chem. Soc. Rev.2021, 50, 11614–11667; Kolhatkar, A. G.; Jamison, A. C.; Litvinov, D.; Willson, R. C.; Lee, T. R. Tuning the Magnetic Properties of Nanoparticles. Int. J. Mol. Sci. 2013, 14, 15977–16009; Chen, Y.-T.; Kolhatkar, A. G.; Zenasni, O.; Xu, S.; Lee, T. R. Biosensing Using Magnetic Particle Detection Techniques. Sensors 2017, 17, 2300). The increase in M_S in the superclusters can be rationalized by considering the reduction of spin misalignment or disordered spins on the surfaces of the individual nanoparticles and at the interfaces between the FeO core and the Fe₃O₄ shell due to enhanced interparticle interactions when assembled. The formation of the superclusters also shifts the T_B to higher temperatures. The T_B is defined here as the temperature that separates the high-temperature SPM state (T > T_B) from the low-temperature FM state (T < T_B). The shift of T_B toward higher temperatures and the flattening feature of zero-field-cooled (ZFC) M(T) curves both imply stronger magnetic interactions among particles (Phan, M.-H.; Alonso, J.; Khurshid, H.; Lampen- Kelley, P.; Chandra, S.; Stojak Repa, K.; Nemati, Z.; Das, R.; Iglesias, Ó.; Srikanth, H. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems. Nanomaterials 2016, 6, 221). However, the average values of T_B for the superclusters are well below 300 K, preserving the excellent SPM ^{4913-4975-3383.1} Page 38 of 144 094876-000024WOPT properties of their individual nanoparticles. Surprisingly, the supercluster particles in FIG. 11C, FIG. 11E, FIG. 11F, which are approximately 240 nm in size, exhibit different values of T_B and M_S, demonstrating the possibility of fine-tuning the SPM properties of supercluster particles by controlling the size and shape of their individual core/shell IONPs, as well as the FeO/Fe₃O₄ phase ratio. Notably, different magnetic properties were observed in supercluster particles approximately 150 nm in size, which were made from nanospheres with a size of 13.1 nm and nanocubes with a size of 10.2 nm. [0103] Herein, we present a practical approach to fine-tuning the superparamagnetic (SPM) properties of iron oxide nanoparticles (IONPs) through the selection of specific structures and the formation of superclusters, which are desirable for advanced biosensing and biomedical applications. We have found that FeO@Fe₃O₄ nanoparticles, in both spherical and cubic shapes synthesized via thermal decomposition of iron oleates, show reduced saturation magnetization as particle size increases due to the larger fraction of the antiferromagnetic (AFM) FeO phase. Compared to their nanosphere counterparts, the FeO@Fe₃O₄ nanocubes exhibit superior SPM properties. The formation of superclusters from these individual IONPs significantly enhances both the saturation magnetization and the blocking temperature (T_B) while retaining SPM characteristics. By tailoring the size and shape of individual nanoparticles, it is possible to create supercluster structures of comparable sizes with distinct magnetic responses. Our research underscores the potential of manipulating the magnetic functionalities of IONPs through structural and morphological modifications, providing a new pathway to develop nanomaterials with desirable magnetic properties for specific uses in sensing, diagnostics, and therapy. Understanding the magnetic properties of these nanosystems also advances the fields of nanotechnology and materials science. [0104] Chapter 3 [0105] In various embodiments the present invention provides Fine-Tuning the Superparamagnetic Properties of FeO@Fe₃O₄ Core/Shell Nanoparticles and Superclusters by Controlling Size and Shape. [0106] Fine-tuning the superparamagnetic (SPM) properties of iron oxide core/shell nanoparticles (NPs), with precise control over size and shape, and their formation into superclusters, is crucial for advanced biomedical applications and electronic devices. We analyzed the size-dependent magnetic properties of FeO@Fe₃O₄ core/shell NPs in both spherical and cubic ^{4913-4975-3383.1} Page 39 of 144 094876-000024WOPT shapes prepared via the thermal decomposition of iron oleate. The analyses provided significant insights for designing and fabricating superclusters by assembling a plurality of individual nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy analyses confirmed the presence of both FeO and Fe₃O₄ phases and the formation of the core/shell structure, with an increasing FeO/Fe₃O₄ phase ratio correlated with particle size. The SPM properties of these core/shell NPs were maintained, although saturation magnetization varied with size, shape, and FeO/Fe₃O₄ ratio. Notably, iron oxide nanocubes exhibited enhanced saturation magnetization compared to their spherical counterparts. We introduced a unique strategy to enhance and fine-tune the SPM properties of FeO@Fe₃O₄ NPs by assembling them into supercluster particles. Magnetometry measurements indicated that supercluster formation promotes interparticle interactions and enhances magnetic properties. By controlling the size and shape of the individual nanoparticles, we demonstrated the creation of SPM superclusters of consistent sizes, including the 150 nm and 240 nm superclusters reported here. This study demonstrates the pivotal role of individual nanoparticles in fine-tuning the SPM properties of supercluster particles. Our research presents a synthetic strategy for designing the SPM properties of iron oxide core/shell NPs and their superclusters for a wide range of magnetically driven applications. [0107] Magnetic iron oxide nanoparticles (IONPs) possessing superparamagnetic (SPM) properties and exceptional biocompatibility offer enormous potential in advanced biomedical applications, including magnetic resonance imaging (MRI), drug delivery, magnetic hyperthermia, and biosensing (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci. 2021, 11, 11301; Tran, H.-V.; Ngo, N. M.; Medhi, R.; Srinoi, P.; Liu, T.; Rittikulsittichai, S.; Lee, T. R. Multifunctional Iron Oxide Magnetic Nanoparticles for Biomedical Applications: A Review. Materials 2022, 15, 503). The utility of SPM properties lies in their ability to be manipulated and the capability to switch on and off under a magnetic field. In contrast to ferrimagnetic (FiM) or ferromagnetic (FM) properties, SPM properties excel in minimizing interparticle interactions, thereby reducing particle aggregation. This feature enhances the dispersibility of nanoparticles (NPs) in colloidal solutions and facilitates their redispersion after magnetic separation. Consequently, tailoring the magnetic properties of IONPs by controlling their structure emerges as a crucial strategy for understanding nano-magnetism and designing NPs for specific biomedical ^{4913-4975-3383.1} Page 40 of 144 094876-000024WOPT applications (Gavilán, H.; Kumar Avugadda, S.; Fernández-Cabada, T.; Soni, N.; Cassani, M.; T. Mai, B.; Chantrell, R.; Pellegrino, T. Magnetic Nanoparticles and Clusters for Magnetic Hyperthermia: Optimizing Their Heat Performance and Developing Combinatorial Therapies to Tackle Cancer. Chem. Soc. Rev. 2021, 50, 11614–11667; Gavilán, H.; Posth, O.; Bogart, L. K.; Steinhoff, U.; Gutiérrez, L.; Morales, M. P. How Shape and Internal Structure Affect the Magnetic Properties of Anisometric Magnetite Nanoparticles. Acta Mater.2017, 125, 416–424). [0108] Typically, IONPs with SPM properties are single-domain particles with sizes smaller than 25 nm (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci.2021, 11, 11301; Kolhatkar, A. G.; Jamison, A. C.; Litvinov, D.; Willson, R. C.; Lee, T. R. Tuning the Magnetic Properties of Nanoparticles. Int. J. Mol. Sci. 2013, 14, 15977–16009). Although the transition size from SPM to FM behavior is generally considered to be around 25 nm, this size can vary depending on the shapes (spheres, cubes, rods) and compositions of the NPs (Fe₃O₄, FeO, γ-Fe₂O₃, α-Fe₂O₃). Additionally, SPM properties can be observed in larger IONPs, above 100 nm, if these particles are secondary structures formed through the stacking of single- domain-size crystals in polycrystalline particles (Xuan, S.; Wang, Y.-X. J.; Yu, J. C.; Cham-Fai Leung, K. Tuning the Grain Size and Particle Size of Superparamagnetic Fe₃O₄ Microparticles. Chem. Mater. 2009, 21, 5079–5087; Ge, J.; Hu, Y.; Biasini, M.; Beyermann, W. P.; Yin, Y. Superparamagnetic Magnetite Colloidal Nanocrystal Clusters. Angew. Chem. Int. Ed. 2007, 46, 4342–4345; Nguyen, M. D.; Deng, L.; Lee, J. M.; Resendez, K. M.; Fuller, M.; Hoijang, S.; Robles Hernandez, F. C.; Chu, C.-W.; Litvinov, D.; Hadjiev, V. G.; Xu, S.; Phan, M.-H.; Lee, T. R. Magnetic Tunability via Control of Crystallinity and Size in Polycrystalline Iron Oxide Nanoparticles. Small 2024, 20, 2402940) or through the assembly of SPM IONPs (Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc.2007, 129, 14166–14167; Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc. 2018, 140, 15038–15047; Wang, T.; Wang, X.; LaMontagne, D.; Wang, Z.; Wang, Z.; Cao, Y. C. Shape-Controlled Synthesis of Colloidal Superparticles from Nanocubes. J. Am. Chem. Soc.2012, 134, 18225–18228). Indeed, large-size SPM IONPs (size > 100 nm) have been reported from polycrystalline NPs with small crystallite sizes (Xuan, S.; Wang, Y.-X. J.; Yu, J. C.; Cham-Fai ^{4913-4975-3383.1} Page 41 of 144 094876-000024WOPT Leung, K. Tuning the Grain Size and Particle Size of Superparamagnetic Fe₃O₄ Microparticles. Chem. Mater.2009, 21, 5079–5087; Ganesan, V.; Lahiri, B. B.; Louis, C.; Philip, J.; Damodaran, S. P. Size-Controlled Synthesis of Superparamagnetic Magnetite Nanoclusters for Heat Generation in an Alternating Magnetic Field. J. Mol. Liq. 2019, 281, 315–323), and from superclusters of single-domain IONP assemblies (Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc.2007, 129, 14166–14167; Wang, T.; Wang, X.; LaMontagne, D.; Wang, Z.; Wang, Z.; Cao, Y. C. Shape-Controlled Synthesis of Colloidal Superparticles from Nanocubes. J. Am. Chem. Soc.2012, 134, 18225–18228; Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256), or from clusters of single-domain SPM IONPs encapsulated in a polymer matrix or an inorganic shell (Yoon, T.-J.; Lee, H.; Shao, H.; Hilderbrand, S. A.; Weissleder, R. Multicore Assemblies Potentiate Magnetic Properties of Biomagnetic Nanoparticles. Adv. Mater. 2011, 23, 4793–4797). Among these three types of large-size SPM IONPs, supercluster particles (assemblies of single-domain IONPs) offer flexibility in manipulating particle structures compared to polycrystalline particles, while minimizing the non-magnetic component, unlike the encapsulated particles. Consequently, tuning the size, shape, and compositions of individual nanoparticles is key to forming unique supercluster structures with desirable properties for advanced biomedical applications. [0109] While maintaining the benefits of SPM properties, large-size SPM IONPs offer advantages such as stronger saturation magnetization through the collective close interactions of component SPM nanoparticles, facilitating efficient magnetic separation (Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc.2018, 140, 15038–15047; Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self- Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). This advantage holds immense potential for biomedical applications, positioning large-size SPM IONPs as a viable alternative to smaller SPM IONPs with sizes less than 30 nm. Despite the extensive use of SPM IONPs in biomedicine, concerns about toxicity persist due to their small size, which may lead to deep penetration and retention in sensitive areas of the body (D, R.; Rao, P. Nanoparticles: Is Toxicity a ^{4913-4975-3383.1} Page 42 of 144 094876-000024WOPT Concern? EJIFCC 2011, 22, 92–101; Moura, R. P.; Almeida, A.; Sarmento, B. The Role of Non- Endothelial Cells on the Penetration of Nanoparticles through the Blood Brain Barrier. Progress in Neurobiology 2017, 159, 39–49; Kefeni, K. K.; Msagati, T. A. M.; Nkambule, T. TI.; Mamba, B. B. Spinel Ferrite Nanoparticles and Nanocomposites for Biomedical Applications and Their Toxicity. Mater. Sci. Eng. C 2020, 107, 110314). Therefore, utilizing large SPM IONPs with improved magnetic properties, such as enhanced saturation magnetization, presents an alternative approach with significant potential in biomedicine, deserving of more attention and further exploration. Dynabead M280 SPM particles, with a size of 2.8 μm (clusters of SPM IONPs dispersed in a polymer matrix), are a prominent example of such large SPM particles useful in bio- detection and bio-purification (Chen, Y.-T.; Medhi, R.; Nekrashevich, I.; Litvinov, D.; Xu, S.; Lee, T. R. Specific Detection of Proteins Using Exceptionally Responsive Magnetic Particles. Anal. Chem. 2018, 90, 6749–6756; Chen, Y.-T.; Kolhatkar, A. G.; Zenasni, O.; Xu, S.; Lee, T. R. Biosensing Using Magnetic Particle Detection Techniques. Sensors 2017, 17, 2300). Recent studies have demonstrated the high efficiency of large SPM IONPs as magnetic agents in biosensing and MRI (Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256; Wu, C.; Xu, Y.; Yang, L.; Wu, J.; Zhu, W.; Li, D.; Cheng, Z.; Xia, C.; Guo, Y.; Gong, Q.; Song, B.; Ai, H. Negatively Charged Magnetite Nanoparticle Clusters as Efficient MRI Probes for Dendritic Cell Labeling and In Vivo Tracking. Adv. Funct. Mater.2015, 25, 3581– 3591; Cai, Z.; Wu, C.; Yang, L.; Wang, D.; Ai, H. Assembly-Controlled Magnetic Nanoparticle Clusters as MRI Contrast Agents. ACS Biomater. Sci. Eng.2020, 6, 2533–2542). Interestingly, the Pellegrino group reported the improved hyperthermia properties of clusters comprising small iron oxide nanocubes, suggesting the use of large SPM IONPs as an efficient approach to hyperthermia- based cancer treatment (Niculaes, D.; Lak, A.; Anyfantis, G. C.; Marras, S.; Laslett, O.; Avugadda, S. K.; Cassani, M.; Serantes, D.; Hovorka, O.; Chantrell, R.; Pellegrino, T. Asymmetric Assembling of Iron Oxide Nanocubes for Improving Magnetic Hyperthermia Performance. ACS Nano 2017, 11, 12121–12133). Our recent study has also revealed the large magnetic hyperthermia responses of large polycrystalline IONPs, with sizes ranging from 160 to 400 nm at a small dose of 0.5 mg/mL (Attanayake, S. B.; Nguyen, M. D.; Chanda, A.; Alonso, J.; Orue, I.; Lee, T. R.; Srikanth, H.; Phan, M.-H. Superparamagnetic Superparticles for Magnetic Hyperthermia Therapy: ^{4913-4975-3383.1} Page 43 of 144 094876-000024WOPT Overcoming the Particle Size Limit. ACS Appl. Mater. Interfaces 2025, (submitted), 10.48550/arXiv.2411.17172). [0110] To date, two methods have been developed for producing SPM IONPs with tunable sizes and shapes: the thermal decomposition of iron(III) acetylacetonate in benzyl ether, and the thermal decomposition of iron(III) oleate in non-polar solvents (hexadecane, octadecene, tetradecane, docosane) (Kim, D.; Lee, N.; Park, M.; Kim, B. H.; An, K.; Hyeon, T. Synthesis of Uniform Ferrimagnetic Magnetite Nanocubes. J. Am. Chem. Soc. 2009, 131, 454–455; Kim, D.; Lee, N.; Park, M.; Kim, B. H.; An, K.; Hyeon, T. Synthesis of Uniform Ferrimagnetic Magnetite Nanocubes. J. Am. Chem. Soc.2009, 131, 454–455; Muro-Cruces, J.; Roca, A. G.; López-Ortega, A.; Fantechi, E.; del-Pozo-Bueno, D.; Estradé, S.; Peiró, F.; Sepúlveda, B.; Pineider, F.; Sangregorio, C.; Nogues, J. Precise Size Control of the Growth of Fe₃O₄ Nanocubes over a Wide Size Range Using a Rationally Designed One-Pot Synthesis. ACS Nano 2019, 13, 7716–7728; Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core– Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater. 2023, 35, 6201–6219). The former method offers advantages in producing a highly pure Fe₃O₄ phase but faces challenges due to the instability of benzyl ether at high temperatures, which negatively impacts reproducibility and scalability (Muro-Cruces, J.; Roca, A. G.; López-Ortega, A.; Fantechi, E.; del-Pozo-Bueno, D.; Estradé, S.; Peiró, F.; Sepúlveda, B.; Pineider, F.; Sangregorio, C.; Nogues, J. Precise Size Control of the Growth of Fe₃O₄ Nanocubes over a Wide Size Range Using a Rationally Designed One-Pot Synthesis. ACS Nano 2019, 13, 7716–7728; Qiao, L.; Fu, Z.; Li, J.; Ghosen, J.; Zeng, M.; Stebbins, J.; Prasad, P. N.; Swihart, M. T. Standardizing Size- and Shape-Controlled Synthesis of Monodisperse Magnetite (Fe₃O₄) Nanocrystals by Identifying and Exploiting Effects of Organic Impurities. ACS Nano 2017, 11, 6370–6381). On the other hand, the thermal decomposition of iron(III) oleate tends to form the antiferromagnetic (AFM) FeO phase within the core of Fe₃O₄ particles; however, its higher reproducibility makes it more suitable for larger-scale synthesis of particles (Estrader, M.; López-Ortega, A.; V. Golosovsky, I.; Estradé, S.; G. Roca, A.; Salazar- Alvarez, G.; López-Conesa, L.; Tobia, D.; Winkler, E.; D. Ardisson, J.; A. Macedo, W. A.; Morphis, A.; Vasilakaki, M.; N. Trohidou, K.; Gukasov, A.; Mirebeau, I.; L. Makarova, O.; D. Zysler, R.; Peiró, F.; Dolors Baró, M.; Bergström, L.; Nogués, J. Origin of the Large Dispersion ^{4913-4975-3383.1} Page 44 of 144 094876-000024WOPT of Magnetic Properties in Nanostructured Oxides: Fe_xO/Fe₃O₄ Nanoparticles as a Case Study. Nanoscale 2015, 7, 3002–3015; Wetterskog, E.; Tai, C.-W.; Grins, J.; Bergström, L.; Salazar- Alvarez, G. Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures: Topotaxial Oxidation of Fe_1-xO|Fe_3−δO₄ Core|Shell Nanocubes to Single-Phase Particles. ACS Nano 2013, 7, 7132–7144; Feld, A.; Weimer, A.; Kornowski, A.; Winckelmans, N.; Merkl, J.-P.; Kloust, H.; Zierold, R.; Schmidtke, C.; Schotten, T.; Riedner, M.; Bals, S.; Weller, H. Chemistry of Shape-Controlled Iron Oxide Nanocrystal Formation. ACS Nano 2019, 13, 152–162). Due to its AFM nature, the presence of the FeO phase usually reduces the overall saturation magnetization of the system; however, magnetic coupling with the FiM Fe₃O₄ phase can enhance magnetic anisotropy, rendering it useful for specific biomedical applications. The exchange coupling between the AFM FeO core and the FiM Fe₃O₄ shell has been shown to improve magnetic anisotropy, leading to enhanced magnetic hyperthermia responses in FeO@Fe₃O₄ core/shell NPs (Khurshid, H.; Alonso, J.; Nemati, Z.; Phan, M. H.; Mukherjee, P.; Fdez-Gubieda, M. L.; Barandiarán, J. M.; Srikanth, H. Anisotropy Effects in Magnetic Hyperthermia: A Comparison between Spherical and Cubic Exchange-Coupled FeO/Fe₃O₄ Nanoparticles. J. Appl. Phys.2015, 117, 17A337; Lee, J.-H.; Jang, J.; Choi, J.; Moon, S. H.; Noh, S.; Kim, J.; Kim, J.-G.; Kim, I.-S.; Park, K. I.; Cheon, J. Exchange-Coupled Magnetic Nanoparticles for Efficient Heat Induction. Nat. Nanotechnol.2011, 6, 418–422). However, to the best of our knowledge, the effect of varying FeO/Fe₃O₄ ratio on the magnetic and hyperthermia properties of the FeO@Fe₃O₄ core/shell system and their superclusters has not been systematically studied for both spherical and cubic shapes. From a different perspective, the exchange-coupled FeO@Fe₃O₄ core/shell systems have also been reported to exhibit an exchange-bias (EB) phenomenon, making them attractive for applications in spintronics and magnetic recording (Pichon, B. P.; Gerber, O.; Lefevre, C.; Florea, I.; Fleutot, S.; Baaziz, W.; Pauly, M.; Ohlmann, M.; Ulhaq, C.; Ersen, O.; Pierron-Bohnes, V.; Panissod, P.; Drillon, M.; Begin-Colin, S. Microstructural and Magnetic Investigations of Wüstite-Spinel Core- Shell Cubic-Shaped Nanoparticles. Chem. Mater.2011, 23, 2886–2900; Phan, M.-H.; Alonso, J.; Khurshid, H.; Lampen-Kelley, P.; Chandra, S.; Stojak Repa, K.; Nemati, Z.; Das, R.; Iglesias, Ó.; Srikanth, H. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems. Nanomaterials 2016, 6, 221). These observations have led us to propose employing the thermal decomposition of iron oleates as a method to produce core/shell IONPs with tunable sizes and shapes, followed by the formation of supercluster structures from these NPs. A clear understanding of the structure- ^{4913-4975-3383.1} Page 45 of 144 094876-000024WOPT property (magnetism) relationship in these nanosystems will help in tuning the SPM properties for diverse applications. [0111] In the work reported here, we synthesized iron oxide nanospheres and iron oxide nanocubes through the thermal decomposition of iron oleate, enabling tunable sizes for a comprehensive study of magnetic properties. The composition of these NP systems included FeO@Fe₃O₄ core/shell structures, with larger particles tending to exhibit a more pronounced FeO phase. Two important parameters -- saturation magnetization and blocking temperature -- for different sizes of nanospheres and nanocubes were investigated for comparison. Experimental data revealed stronger saturation magnetization in the iron oxide nanocubes and provided guidance on selecting IONPs with desirable SPM properties. To further fine-tune the SPM properties, superclusters were fabricated using these selected IONPs (both iron oxide nanospheres and nanocubes) of various sizes and shapes. A systematic analysis of the magnetic properties of the resulting supercluster particles, relative to their individual IONPs, shows a significant improvement in saturation magnetization and a shift in the blocking temperature (T_B) toward higher temperatures. We attributed these enhanced magnetic properties to enhanced magnetic interactions among the individual IONPs that formed the superclusters, desirable for advanced biomedical applications. Surprisingly, the magnetic properties of superclusters of similar sizes can be tuned by varying the size, shape and FeO/Fe₃O₄ ratio of their constituent nanoparticles. This finding underscores the great potential for fine-tuning the SPM properties of core/shell IONPs and their supercluster structures. [0112] Structural and Magnetic Characterization of Iron Oxide Nanoparticles. [0113] The structure and magnetic properties of iron oxide nanoparticles (IONPs) with cubic and spherical shapes were studied by characterizing the nanoparticles (NPs) using transmission electron microscopy (TEM), X-ray diffractometry (XRD), and superconducting quantum interference device (SQUID) measurements. In the context of this paper, the size of particles is defined as the diameter for spherical shapes and edge length for cubic shapes. FIG.1A – FIG. 1I presents TEM images of iron oxide nanospheres (IONSs) with average sizes ranging from 10 nm to 28 nm (FIG.1A – FIG.1E) and iron oxide nanocubes (IONCs) from 10 nm to 18 nm (FIG.1F – FIG. 1I). All NP samples, both spherical and cubic, exhibited uniform sizes with narrow size distributions, where the standard deviation was controlled to be around 10% of the average size. The morphology of both the spherical and cubic NPs was uniformly controlled. ^{4913-4975-3383.1} Page 46 of 144 094876-000024WOPT Therefore, it is reasonable to assert that the synthesized NPs, whether spherical and cubic, are of identical quality with narrow size distributions and uniform morphologies. This uniformity enables subsequent studies focusing on the effects of size and shape on the magnetic properties of IONPs. [0114] FIG. 2A presents the XRD patterns of IONSs and FIG. 2B presents the XRD patterns of IONCs. Two major phases of iron oxide, FeO and Fe₃O₄, were observed, consistent with results from previous studies using a similar synthesis method (Lak, A.; Cassani, M.; Mai, B. T.; Winckelmans, N.; Cabrera, D.; Sadrollahi, E.; Marras, S.; Remmer, H.; Fiorito, S.; Cremades- Jimeno, L.; Litterst, F. J.; Ludwig, F.; Manna, L.; Teran, F. J.; Bals, S.; Pellegrino, T. Fe²⁺ Deficiencies, FeO Subdomains, and Structural Defects Favor Magnetic Hyperthermia Performance of Iron Oxide Nanocubes into Intracellular Environment. Nano Lett.2018, 18, 6856– 6866; Lak, A.; Kraken, M.; Ludwig, F.; Kornowski, A.; Eberbeck, D.; Sievers, S.; J. Litterst, F.; Weller, H.; Schilling, M. Size Dependent Structural and Magnetic Properties of FeO–Fe₃O₄ Nanoparticles. Nanoscale 2013, 5, 12286–12295). The formation of the FeO phase at the core of particles, followed by the Fe₃O₄ phase as the shell, was attributed to the fast growth rate of the nanoparticles, which overwhelmed the oxidation rate of the FeO core (Cotin, G.; Perton, F.; Petit, C.; Sall, S.; Kiefer, C.; Begin, V.; Pichon, B.; Lefevre, C.; Mertz, D.; Greneche, J.-M.; Begin- Colin, S. Harnessing Composition of Iron Oxide Nanoparticle: Impact of Solvent-Mediated Ligand–Ligand Interaction and Competition between Oxidation and Growth Kinetics. Chem. Mater.2020, 32, 9245–9259). To grow larger NPs, a fast growth rate is preferred, leading to a more pronounced formation of the FeO phase. Notably, the larger the size of the NPs, whether spherical and cubic, the more the FeO phase was identified. The largest IONSs, approximately 28 nm in size, prominently matched with the FeO phase, with the center position of peaks corresponding to FeO crystal planes (111), (200), (220), and two minor peaks at (311) and (222) being observable. Three regions in the XRD patterns were crucial for analysis: 2θ from 33° to 38°, 2θ from 41° to 44°, and 2θ from 59° to 64° (Lak, A.; Niculaes, D.; Anyfantis, G. C.; Bertoni, G.; Barthel, M. J.; Marras, S.; Cassani, M.; Nitti, S.; Athanassiou, A.; Giannini, C.; Pellegrino, T. Facile Transformation of FeO/Fe₃O₄ Core-Shell Nanocubes to Fe₃O₄ via Magnetic Stimulation. Sci. Rep. 2016, 6, 33295). In the first region, the diffraction peak of (111) in the FeO phase at 2θ = 36.2° was flanked by the diffraction peaks of (311) at 35.5° and (222) at 37.2° from Fe₃O₄. The maxima of the diffraction peaks were centered at 35.5° of (311) in the magnetite phase for IONSs size 9.8 nm and shifted toward 2θ = 36.2° (FeO (111) planes) for larger particles. For sample sizes of 21.8 ^{4913-4975-3383.1} Page 47 of 144 094876-000024WOPT nm and 28.3 nm for IONSs and 18 nm for IONCs, the maxima in this region were centered at 36.2° for FeO (111). In the region from 41° to 44°, the maxima of the peaks were centered at 43.2° for the (400) planes in magnetite and shifted toward the lower diffraction angle at 42.0° for (200) in FeO. In the region from 61° to 63°, similar trends were observed, where the peak maxima for smaller particles (size 9.8 nm for IONSs and 11.8 nm for IONCs) were positioned at 62.7° and shifted toward the lower diffraction angle of 60.9° for (220) planes in FeO. [0115] From the analysis of the XRD results, we observed an increase in the size of IONPs with a higher ratio of the FeO phase, which impacts the saturation magnetization of the NPs. The (200) peak of FeO is the most prominent, with the highest peak intensity observed in the largest nanospheres (size 28.3 nm) and nanocubes (size 18 nm). By deconvoluting the (200) peak of FeO at around 42.0° and the (400) peak of Fe₃O₄ at 43.2°, the crystallite size of FeO could be estimated,( Lak, A.; Niculaes, D.; Anyfantis, G. C.; Bertoni, G.; Barthel, M. J.; Marras, S.; Cassani, M.; Nitti, S.; Athanassiou, A.; Giannini, C.; Pellegrino, T. Facile Transformation of FeO/Fe₃O₄ Core-Shell Nanocubes to Fe₃O₄ via Magnetic Stimulation. Sci. Rep.2016, 6, 33295; Tancredi, P.; Rivas Rojas, P. C.; Moscoso-Londoño, O.; Wolff, U.; Neu, V.; Damm, C.; Rellinghaus, B.; Knobel, M.; M. Socolovsky, L. Synthesis Process, Size and Composition Effects of Spherical Fe₃O₄ and FeO@Fe₃O₄ Core/Shell Nanoparticles. New J. Chem.2017, 41, 15033–15041) as shown in Table 6. Due to the insignificant amount of the FeO phase in smaller NPs, the crystallite size of the FeO phase in samples sized 9.8 nm (nanospheres), 10.2 nm (nanocubes), and 11.8 nm (nanocubes) could not be determined from XRD deconvolution. The peak positions of these samples mostly coincide with the (400) of the Fe₃O₄ phase; therefore, the crystallite size of Fe₃O₄ along (400) was calculated. The calculated Fe₃O₄ crystallite size closely matches the size of the NPs. Combining the features of XRD patterns with the shift of peak maxima at three regions (2θ from 33° to 38°, 2θ from 41° to 44°, and 2θ from 59° to 64°), as discussed above, and the estimated crystallite sizes specified in Table 6, it is apparent that larger FeO@Fe₃O₄ core-shell NPs could possess a larger volume fraction of the FeO phase in the core/shell structure. It is reasonable to assume that larger particles, spherical or cubic in shape, would have lower saturation magnetization due to the antiferromagnetic nature of FeO. It is also reasonable to assume that the blocking temperature (T_B) will shift toward higher temperatures for larger single-phase Fe₃O₄ particles, since T_B is a size-dependent parameter (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. ^{4913-4975-3383.1} Page 48 of 144 094876-000024WOPT Mater.2004, 3, 891–895; Nozawa, R.; Naka, T.; Kurihara, M.; Togashi, T. Size-Tunable Synthesis of Iron Oxide Nanocrystals by Continuous Seed-Mediated Growth: Role of Alkylamine Species in the Stepwise Thermal Decomposition of Iron(II) Oxalate. Dalton Trans. 2021, 50, 16021– 16029; Baaziz, W.; Pichon, B. P.; Fleutot, S.; Liu, Y.; Lefevre, C.; Greneche, J.-M.; Toumi, M.; Mhiri, T.; Begin-Colin, S. Magnetic Iron Oxide Nanoparticles: Reproducible Tuning of the Size and Nanosized-Dependent Composition, Defects, and Spin Canting. J. Phys. Chem. C 2014, 118, 3795–3810). However, this trend might not occur in biphasic systems like our FeO@Fe₃O₄ core/shell NPs. Changes in T_B are not solely driven by changes in the size and shape of NPs, but also by the FeO/Fe₃O₄ ratio in the entire nanoparticle structure (Wetterskog, E.; Tai, C.-W.; Grins, J.; Bergström, L.; Salazar-Alvarez, G. Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures: Topotaxial Oxidation of Fe_1-xO|Fe_3−δO₄ Core|Shell Nanocubes to Single- Phase Particles. ACS Nano 2013, 7, 7132–7144). [0116] Table 6. Crystallite Sizes of FeO (200) and Fe₃O₄ (400) Determined by XRD. Particle Shape Particle Size (nm) Crystallite Size (nm) Crystallite Size (nm) [0117] Two samples of the largest size, nanospheres (size 28.3 nm) and nanocubes (size 18.0 nm), were further characterized using atomic resolution TEM, and the FFT were simulated for crystallographic analysis. From FIG.9A – FIG.9G, core-shell structures were observed, with the FeO size closely matching the calculated crystallite size values in Table 6. FFT diffraction ^{4913-4975-3383.1} Page 49 of 144 094876-000024WOPT patterns confirmed the existence of FeO as the core, with visible (111) and (200) planes, and Fe₃O₄ as the shell, with visible (220), (311), (222), and (400) planes. As indicated in the XRD results, the FeO phase is more dominant in the larger nanoparticles. Therefore, the smallest sample, nanospheres with average size 9.8 nm, was further characterized. High-resolution TEM and FFT of the nanospheres (size 9.8 nm), shown in FIG. 13, revealed no core-shell structures, with the entire particle indexed to the magnetite phase, showing observable (220) and (311) planes of Fe₃O₄. The atomic-resolution TEM and FFT results are consistent with the analysis from the XRD results. [0118] The XRD patterns can be used to index and identify the presence of different iron oxide phases, such as FeO, Fe₃O₄ or ɣ-Fe₂O₃, and α-Fe₂O₃ (hematite). However, Fe₃O₄ and ɣ- Fe₂O₃ are indistinguishable in XRD patterns due to their similar cubic crystal structures (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci. 2021, 11, 11301; Phan, M.-H.; Alonso, J.; Khurshid, H.; Lampen-Kelley, P.; Chandra, S.; Stojak Repa, K.; Nemati, Z.; Das, R.; Iglesias, Ó.; Srikanth, H. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems. Nanomaterials 2016, 6, 221). Consequently, the shell composition could be Fe₃O₄, ɣ- Fe₂O₃, or a mixture of these two phases. XPS, with its surface sensitivity, was used to further confirm the composition of the shells. FIG.10A – FIG.10B shows the high-resolution XPS spectra of Fe 2p, which confirm the presence of a pure Fe₃O₄ phase without any evidence of ɣ-Fe₂O₃ coexistence (Anderson, J. F.; Kuhn, M.; Diebold, U. Epitaxially Grown Fe₃O₄ Thin Films: An XPS Study. Surf. Sci. Spectra 1996, 4, 266–272). The absence of a satellite peak around 718 eV indicates the absence of ɣ-Fe₂O₃ (Mansour, A. N.; Brizzolara, R. A. Characterization of the Surface of γ-Fe₂O₃ Powder by XPS. Surf. Sci. Spectra 1996, 4, 351–356; Ibrahim Dar, M.; A. Shivashankar, S. Single Crystalline Magnetite, Maghemite, and Hematite Nanoparticles with Rich Coercivity. RSC Adv. 2014, 4, 4105–4113). Therefore, the data from surface-sensitive technique like XPS can conclude the pure Fe₃O₄ phase of the nanoparticle shell. To further confirm the phase composition of nanoparticles, analysis using Raman spectroscopy was conducted with more details on the phase composition in bulk scale. For Raman spectroscopy, maghemite (ɣ- Fe₂O₃) typically exhibits three major peaks centered around 365 cm⁻¹, 510 cm⁻¹, and 700 cm⁻¹. And Raman peaks for magnetite (Fe₃O₄) appear at 310 cm⁻¹, 540 cm⁻¹, and 670 cm⁻¹. For the FeO phase, FeO crystallizes as rock-salt structure in the Fm-3m space group, which is thought to be a ^{4913-4975-3383.1} Page 50 of 144 094876-000024WOPT weak Raman scatterer without proper Raman active modes (Hanesch, M. Raman Spectroscopy of Iron Oxides and (Oxy)Hydroxides at Low Laser Power and Possible Applications in Environmental Magnetic Studies. Geophys. J. Int. 2009, 177, 941–948; Testa-Anta, M.; Rodríguez-González, B.; Salgueiriño, V. Partial FeO–Fe₃O₄ Phase Transition Along the <111> Direction of the Cubic Crystalline Structure in Iron Oxide Nanocrystals. Part. Part. Syst. Charact. 2019, 36, 1900283). All distinct peaks of Fe₃O₄ phase, especially two major peaks at around 670 cm^-1 and 540 cm^-1, were clearly observed, indicating the highly pure Fe₃O₄ phase in nanoparticles (Hanesch, M. Raman Spectroscopy of Iron Oxides and (Oxy)Hydroxides at Low Laser Power and Possible Applications in Environmental Magnetic Studies. Geophys. J. Int. 2009, 177, 941–948; Chamritski, I.; Burns, G. Infrared- and Raman-Active Phonons of Magnetite, Maghemite, and Hematite: A Computer Simulation and Spectroscopic Study. J. Phys. Chem. B 2005, 109, 4965– 4968). For the smallest sample size of 10.2 nm nanocubes, a slight shoulder around 700 cm⁻¹ suggests the presence of a small amount of maghemite. While the coexistence of maghemite and magnetite may be more pronounced in smaller particle sizes (Park, J.; An, K.; Hwang, Y.; Park, J.- G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. 3, 891–895), overheating due to laser exposure during Raman characterization could also result in the formation of a tiny amount of maghemite in the smallest sample (which has a higher surface-to-volume ratio) (Jubb, A. M.; Allen, H. C. Vibrational Spectroscopic Characterization of Hematite, Maghemite, and Magnetite Thin Films Produced by Vapor Deposition. ACS Appl. Mater. Interfaces 2010, 2, 2804–2812; de Faria, D. L. A.; Venâncio Silva, S.; de Oliveira, M. T. Raman microspectroscopy of some iron oxides and oxyhydroxides. J. Raman Spectrosc. 1997, 28, 873–878). Overall, the pure magnetite phase remains the dominant phase in the nanoparticle shell. [0119] Table 7. Magnetic Properties of Iron Oxide Nanospheres and Iron Oxide Nanocubes. Particle Particle Size MS TB (K) Estimated Equivalent Size OPT Nanospheres 28.3 ± 2.5 33.5 272 11861 22.8 (cubes) Nanocubes 10.2 ± 0.9 68.0 187 1061 12.7 (spheres) e e a e e epen ence o magne za on an empera ure dependence of magnetization (M(T)) data of IONPs are presented in FIG. 14A – FIG. 14F and FIG. 15A – FIG. 15E. Table 7 summarizes the magnetic parameters derived from these data for IONPs of different sizes and shapes. For comparison, an equivalent size was calculated as described in the following sentences. For nanospheres, the equivalent size represents the edge length of nanocubes with a similar volume. Similarly, the equivalent size for nanocubes represents the diameter of nanospheres with a similar volume. The shape of the M(H) curves presented in FIG. 14A and FIG. 15A indicates the need for a high magnetic field to saturate the magnetic moment of NPs due to the presence of the AFM FeO core (Testa-Anta, M.; Rodríguez-González, B.; Salgueiriño, V. Partial FeO–Fe₃O₄ Phase Transition Along the <111> Direction of the Cubic Crystalline Structure in Iron Oxide Nanocrystals. Part. Part. Syst. Charact. 2019, 36, 1900283; Baaziz, W.; P. Pichon, B.; Grenèche, J.-M.; Begin-Colin, S. Effect of Reaction Environment and in Situ Formation of the Precursor on the Composition and Shape of Iron Oxide Nanoparticles Synthesized by the Thermal Decomposition Method. CrystEngComm 2018, 20, 7206–7220). Here, we determine the blocking temperature as the temperature at which the maximum magnetization in the ZFC curve is observed, the experimental method that is arguably the most widely accepted to determine the average blocking temperature of superparamagnetic nanoparticles (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra- ^{4913-4975-3383.1} Page 52 of 144 094876-000024WOPT Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater.2004, 3, 891–895; Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core–Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater.2023, 35, 6201–6219; Baaziz, W.; P. Pichon, B.; Grenèche, J.- M.; Begin-Colin, S. Effect of Reaction Environment and in Situ Formation of the Precursor on the Composition and Shape of Iron Oxide Nanoparticles Synthesized by the Thermal Decomposition Method. CrystEngComm 2018, 20, 7206–7220; Ma, Z.; Mohapatra, J.; Wei, K.; Liu, J. P.; Sun, S. Magnetic Nanoparticles: Synthesis, Anisotropy, and Applications. Chem. Rev. 2023, 123, 3904– 3943; Poon, K.; Gupta, A.; Hawkins, P. M. E.; Singh, G. Core-Shell Magnetic Nanoparticles: Harnessing Synergistic Effects for MRI and Magnetic Hyperthermia. Mater. Today Chem.2025, 44, 102533). The magnetic nanoparticle sample was cooled without an applied magnetic field to frozen the Brownian rotations, and a small field (tickling field, typically 10 to 100 Oe) was applied as the magnetization was recorded during warming (Ma, Z.; Mohapatra, J.; Wei, K.; Liu, J. P.; Sun, S. Magnetic Nanoparticles: Synthesis, Anisotropy, and Applications. Chem. Rev.2023, 123, 3904– 3943). As the temperature increases, thermal energy disturbs the system, allowing more magnetic moments to acquire sufficient energy to align with the applied magnetic field. Consequently, magnetization increases, reaching a maximum when the number of unblocked (aligned) moments peaks at the blocking temperature. For the temperature higher than the blocking temperature, the thermal energy becomes strong enough to randomize the magnetic moments, resulting in a reduction in magnetization. Some researchers, however, define the blocking temperature as the bifurcation point of the ZFC and FC curves or by calculating the T derivative of the difference between ZFC and FC curve (d(ZFC-FC)/dT) (Bruvera, I. J.; Mendoza Zélis, P.; Pilar Calatayud, M.; Goya, G. F.; Sánchez, F. H. Determination of the Blocking Temperature of Magnetic Nanoparticles: The Good, the Bad, and the Ugly. J. Appl. Phys. 2015, 118, 184304). While the former is not widely accepted and depends on sample stacking in the powder phase, both alternative methods remain subjects of debate and controversy. [0121] Several important features can be observed in the M(T) curves shown in FIG.14B – FIG.14F and FIG.15B – FIG.15E. First, the Verwey transition (T_V), occurring around 125 K, is characteristic of a pure magnetite phase with good crystalline quality and is observable in the curves (Bohra, M.; Agarwal, N.; Singh, V. A Short Review on Verwey Transition in Nanostructured ^{4913-4975-3383.1} Page 53 of 144 094876-000024WOPT Fe₃O₄ Materials. J. Nanomater. 2019, 2019, e8457383). However, due to the overlap with other magnetic interactions, blocking temperature effects, or dependence on the applied field during M(T) measurements, T_V typically manifests as a subtle kink at approximately 110–125 K (e.g., FIG.14C) or as a steep increase in magnetization in the ZFC curve around 100–150 K (e.g., FIG. 15C, FIG.15D). Second, the Néel temperature (T_N) of the FeO phase, known as the transition from antiferromagnetic to a paramagnetic spin configuration of wüstite core, is clearly identified as a steep increase in magnetization starting at approximately 190 K (Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core–Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater.2023, 35, 6201–6219; Lak, A.; Kraken, M.; Ludwig, F.; Kornowski, A.; Eberbeck, D.; Sievers, S.; J. Litterst, F.; Weller, H.; Schilling, M. Size Dependent Structural and Magnetic Properties of FeO–Fe₃O₄ Nanoparticles. Nanoscale 2013, 5, 12286–12295; Lak, A.; Niculaes, D.; Anyfantis, G. C.; Bertoni, G.; Barthel, M. J.; Marras, S.; Cassani, M.; Nitti, S.; Athanassiou, A.; Giannini, C.; Pellegrino, T. Facile Transformation of FeO/Fe₃O₄ Core-Shell Nanocubes to Fe₃O₄ via Magnetic Stimulation. Sci. Rep.2016, 6, 33295; Lohr, J.; Vasquez Mansilla, M.; Gerbaldo, M. V.; Moreno, M. S.; Tobia, D.; Goya, G. F.; Winkler, E. L.; Zysler, R. D.; Lima, E. Dependence of the Composition, Morphology and Magnetic Properties with the Water and Air Exposure during the Fe_1-yO/Fe₃O₄ Core–Shell Nanoparticles Synthesis. J. Nanopart. Res. 2021, 23, 140), as illustrated in FIG. 14C, FIG. 14D, FIG. 14E, FIG. 14F and FIG. 15D, FIG. 15E. Samples with smaller sizes, which are estimated to have negligible FeO cores (e.g., spherical particles with a size of 9.8 nm and cubic nanoparticles with sizes of 10.2 and 11.8 nm), do not exhibit this behavior in their ZFC curves. The M(T) curves further corroborate the structural and compositional analysis of the nanoparticles. The bi-phase antiferromagnetic/ferrimagnetic nature of FeO@Fe₃O₄ core/shell nanoparticles has been further confirmed by the observed shapes of the M(H) curves measured at 10 K under both ZFC and FC (3T) measurement protocols, as shown in FIG. 20A, FIG.20B. It is worth noticing that the ferrimagnetic Fe₃O₄ shell dominates the low-field behavior of the M(H) loops, while the open-up of the loops arises from the antiferromagnetic FeO core. [0122] Two trends can be drawn from our magnetic data: first, the T_B increases with the size of the particles; second, the saturation magnetization (M_S) appears to decrease in particles with larger sizes. FIG.4A – FIG.4B presents the M_S versus size relation, showing a trend of M_S ^{4913-4975-3383.1} Page 54 of 144 094876-000024WOPT decreasing for larger particles. This reduction might be due to the AFM enhancement of the FeO core at the expense of the FiM Fe₃O₄ shell, thus reducing the total magnetic moment in larger particles. In this dataset, the 15.6 nm nanospheres slightly deviate from the trend of saturation magnetization versus particle size. While the spherical samples have nearly similar FeO core sizes—4.0 nm for the sample size 15.6 nm and 4.3 nm for the sample size 13.1 nm—the volume fraction of FeO is more dominant in the 13.1 nm sample, resulting in weaker saturation magnetization. Although it was initially hypothesized that the FeO core size in the 15.6 nm sample would be larger than 4.3 nm—ensuring a more systematic and perfectly trended dataset—this minor deviation is realistic and falls within the acceptable margin of error for nanoparticle synthesis and characterization. The M_S values of IONCs appear to be higher than those of IONSs, probably due to the enhanced crystallinity in the former. The data in Table 7 provide good guidance on selecting NPs with desired SPM properties for biomedical applications and for forming their supercluster structures. The reduction in M_S due to an increasing volume of the FeO phase, as estimated in Table 6, illustrates the relationship between the M_S and particle size in these core/shell IONPs. [0123] From Table 7, we can compare the properties of IONCs with IONSs of comparable volumes. Three pairs of samples were compared: (a) 13.1 ± 1.0 nm (nanospheres) versus 10.2 ± 0.9 nm (nanocubes), (b) 15.6 ± 1.3 nm (nanospheres) versus 11.8 ± 1.3 nm (nanocubes), and (c) 21.8 ± 2.0 nm (nanospheres) versus 18.0 ± 1.4 nm (nanocubes). The comparisons show that the M_S values of IONCs are higher than those of IONSs, largely due to the dominance of the FiM Fe₃O₄ phase compared to the AFM FeO phase in the former (see Table 6). Calculating the M_S (nanocubes)/M_S (nanospheres) ratio for the three pairs of samples, the ratios are 1.47, 1.27, and 1.14, respectively. This analysis confirms the superior magnetic properties of core/shell IONCs compared to their IONS counterparts for biomedical applications. [0124] SPM Properties of Superclusters. [0125] The superclusters were formed through the self-assembly of IONPs, using oil droplets in a microemulsion as templates to form the supercluster structures (Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self- Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). FIG. 11A – FIG. 11F presents SEM images of superclusters fabricated from individual nanoparticles of various sizes and shapes. The ^{4913-4975-3383.1} Page 55 of 144 094876-000024WOPT size distribution histograms are presented in FIG.18A – FIG.18F. The superclusters have rounded shapes with a broad size distribution, which can be attributed to the diverse size distribution of droplets formed in the emulsion. Our synthesis results showed that in some instances forming supercluster particles requires a specific concentration of NP colloidal solution in chloroform with good dispersibility. From the examples studied, the larger the size of the individual nanoparticles, the higher the concentration of colloidal solution needed to form the superclusters, as specified in Table 14 (see in Examples section herein). [0126] Table 8. Magnetic Properties of Nanoparticles and Their Corresponding Superclusters. Structures Size (nm) Magnetic Field (0.3 T) Magnetic Field (4 T) TB Shift M % M % (K) ^{f T} _B K K K K rs [0127] The M(H) and M(T) data of the nanoparticles and their corresponding superclusters are presented in FIG.16A – FIG.16D and FIG.17A – FIG.17F. Table 8 summarizes the magnetic parameters deduced from these data for the superclusters and their constituent nanoparticles. The data show that the formation of superclusters significantly enhances the M_S values compared to those of their constituent nanoparticles. The enhancement of magnetization in the supercluster particles relative to their individual IONPs is unexpected, especially at low fields (FIG.16A – FIG. ^{4913-4975-3383.1} Page 56 of 144 094876-000024WOPT 16D and FIG. 17A – FIG. 17F). This property is extremely useful for enhancing magnetic biosensing, MRI contrast, and hyperthermia efficiency (Nguyen, M. D.; Tran, H.-V.; Xu, S.; Lee, T. R. Fe₃O₄ Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications. Appl. Sci. 2021, 11, 11301; Gavilán, H.; Kumar Avugadda, S.; Fernández-Cabada, T.; Soni, N.; Cassani, M.; T. Mai, B.; Chantrell, R.; Pellegrino, T. Magnetic Nanoparticles and Clusters for Magnetic Hyperthermia: Optimizing Their Heat Performance and Developing Combinatorial Therapies to Tackle Cancer. Chem. Soc. Rev.2021, 50, 11614–11667; Kolhatkar, A. G.; Jamison, A. C.; Litvinov, D.; Willson, R. C.; Lee, T. R. Tuning the Magnetic Properties of Nanoparticles. Int. J. Mol. Sci. 2013, 14, 15977–16009; Chen, Y.-T.; Kolhatkar, A. G.; Zenasni, O.; Xu, S.; Lee, T. R. Biosensing Using Magnetic Particle Detection Techniques. Sensors 2017, 17, 2300). The increase in M_S in the superclusters can be rationalized by considering the reduction of spin misalignment or disordered spins on the surfaces of the individual nanoparticles and at the interfaces between the FeO core and the Fe₃O₄ shell due to enhanced interparticle interactions when assembled. In addition, in some instances the core FeO may partially transform into magnetite during the formation of the superclusters, which could contribute to the observed increase in saturation magnetization. However, an enhancement in saturation magnetization is also observed in samples composed of small individual nanoparticles (e.g., 13.1 nm nanospheres and 10.2 nm nanocubes), where the presence of FeO is negligible. The presence of FeO and the exchange coupling between the FeO core and the Fe₃O₄ shell in the FeO/Fe₃O₄ core/shell nanospheres (size 21.8 nm) are observed to be preserved in their superclusters with a size of 249 nm, as shown in FIG.21. The formation of the superclusters also shifts the T_B to higher temperatures. The T_B is defined here as the temperature that separates the high-temperature SPM state (T > T_B) from the low-temperature FiM state (T < T_B). The shift of T_B toward higher temperatures and the flattening feature of zero-field-cooled (ZFC) M(T) curves both imply stronger magnetic interactions among particles (Phan, M.-H.; Alonso, J.; Khurshid, H.; Lampen- Kelley, P.; Chandra, S.; Stojak Repa, K.; Nemati, Z.; Das, R.; Iglesias, Ó.; Srikanth, H. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems. Nanomaterials 2016, 6, 221). However, the average values of T_B for the superclusters are well below 300 K, preserving the excellent SPM properties of their individual nanoparticles. Surprisingly, the supercluster particles in FIG. 11C, FIG. 11E, and FIG. 11F, which are approximately 240 nm in size, exhibit different values of T_B and M_S, demonstrating the possibility of fine-tuning the SPM properties of supercluster particles ^{4913-4975-3383.1} Page 57 of 144 094876-000024WOPT by controlling the size and shape of their individual core/shell IONPs, as well as the FeO/Fe₃O₄ phase ratio. Notably, different magnetic properties were observed in supercluster particles approximately 150 nm in size, which were made from nanospheres with a size of 13.1 nm and nanocubes with a size of 10.2 nm. [0128] In this study, we demonstrate for the first time that the superparamagnetic properties of superclusters can be finely tuned in terms of both saturation magnetization and blocking temperature. These parameters significantly influence the performance of nanoparticles in biomedical applications, such as MRI, hyperthermia, and biosensing, due to the synergistic interplay between these parameters and their effects on magnetization capability, magnetic relaxation, inter-particle interactions, and the Brownian motion of particles (Gavilán, H.; Kumar Avugadda, S.; Fernández-Cabada, T.; Soni, N.; Cassani, M.; T. Mai, B.; Chantrell, R.; Pellegrino, T. Magnetic Nanoparticles and Clusters for Magnetic Hyperthermia: Optimizing Their Heat Performance and Developing Combinatorial Therapies to Tackle Cancer. Chem. Soc. Rev. 2021, 50, 11614–11667; Ma, Z.; Mohapatra, J.; Wei, K.; Liu, J. P.; Sun, S. Magnetic Nanoparticles: Synthesis, Anisotropy, and Applications. Chem. Rev.2023, 123, 3904–3943; Haun, J. B.; Yoon, T.- J.; Lee, H.; Weissleder, R. Magnetic Nanoparticle Biosensors. WIREs Nanomedicine and Nanobiotechnology 2010, 2, 291–304). Given the growing interest in utilizing this class of materials for diverse biological and biomedical applications (Kim, S.; Kim, J.; Im, J.; Kim, M.; Kim, T.; Wang, S. X.; Kim, D.; Lee, J.-R. Magnetic Supercluster Particles for Highly Sensitive Magnetic Biosensing of Proteins. Microchim Acta 2022, 189, 256; Wu, C.; Xu, Y.; Yang, L.; Wu, J.; Zhu, W.; Li, D.; Cheng, Z.; Xia, C.; Guo, Y.; Gong, Q.; Song, B.; Ai, H. Negatively Charged Magnetite Nanoparticle Clusters as Efficient MRI Probes for Dendritic Cell Labeling and In Vivo Tracking. Adv. Funct. Mater. 2015, 25, 3581–3591; Cai, Z.; Wu, C.; Yang, L.; Wang, D.; Ai, H. Assembly-Controlled Magnetic Nanoparticle Clusters as MRI Contrast Agents. ACS Biomater. Sci. Eng. 2020, 6, 2533–2542; Hong, H.; Min, S.; Koo, S.; Lee, Y.; Yoon, J.; Jang, W. Y.; Kang, N.; Thangam, R.; Choi, H.; Jung, H. J.; Han, S.-B.; Wei, Q.; Yu, S.-H.; Kim, D.-H.; Paulmurugan, R.; Jeong, W. K.; Lee, K.-B.; Hyeon, T.; Kim, D.; Kang, H. Dynamic Ligand Screening by Magnetic Nanoassembly Modulates Stem Cell Differentiation. Adv. Mater. 2022, 34, 2105460), this approach offers an effective strategy to design nanoparticle configurations for maximum efficiency or to tailor their properties to achieve a specific range of magnetic responses or performances. For instance, magnetic particles of similar sizes but with different magnetic properties can serve as ^{4913-4975-3383.1} Page 58 of 144 094876-000024WOPT magnetic labeling agents for distinct biomolecules or antibodies, and can be integrated into detection platforms and microfluidic devices, enabling differentiation in magnetic signals for efficient biodetection (Hwang, K. Y.; Brown, D.; Attanayake, S. B.; Luu, D.; Nguyen, M. D.; Lee, T. R.; Phan, M.-H. Signal Differentiation of Moving Magnetic Nanoparticles for Enhanced Biodetection and Diagnostics. Biosensors 2025, 15, 116. Furthermore, these applications can extend to electronic devices, sensing technologies, and spintronics, where the utilization of magnetic properties (superparamagnetic or ferromagnetic) can be adjusted to align with the operating temperature range of the devices. [0129] Herein, we present a practical approach to fine-tuning the superparamagnetic properties of iron oxide nanoparticles (IONPs) through the selection of specific structures and the formation of superclusters, which are desirable for advanced biosensing and biomedical applications. We have found that FeO@Fe₃O₄ nanoparticles, in both spherical and cubic shapes synthesized via thermal decomposition of iron(III) oleate, show reduced saturation magnetization as particle size increases due to the larger fraction of the antiferromagnetic FeO phase. Compared to their nanosphere counterparts, the FeO@Fe₃O₄ nanocubes exhibit superior superparamagnetic properties. The formation of superclusters from these individual IONPs significantly enhances both the saturation magnetization and the blocking temperature (T_B) while retaining superparamagnetic characteristics. By tailoring the size and shape of individual nanoparticles, it is possible to create supercluster structures of comparable sizes with distinct magnetic responses. Our research underscores the potential of manipulating the magnetic functionalities of IONPs through structural and morphological modifications, providing a new pathway to develop nanomaterials with desirable magnetic properties for specific uses in sensing, diagnostics, and therapy. Understanding the magnetic properties of these nanosystems also advances the fields of nanotechnology and materials science. [0130] Various Non-Limiting Embodiments of the Invention [0131] Embodiments include those listed below. [0132] Embodiment 1. A supercluster, comprising: a plurality of magnetic nanoparticles. [0133] Embodiment 2. The supercluster of embodiment 1, wherein the plurality of magnetic nanoparticles comprise iron oxide. [0134] Embodiment 3. The supercluster of embodiment 2, wherein the iron oxide is FeO, Fe₃O₄, or combination thereof. ^{4913-4975-3383.1} Page 59 of 144 094876-000024WOPT [0135] Embodiment 4. The supercluster of embodiment 1, wherein the plurality of magnetic nanoparticles comprise a core, and a shell surrounding the core. [0136] Embodiment 5. The supercluster of embodiment 4, wherein the core comprises FeO, and the shell comprises Fe₃O₄. [0137] Embodiment 6. The supercluster of embodiment 4, wherein the shell is coated with an oleic acid capping agent. [0138] Embodiment 7. The supercluster of any one of embodiments 1-6, wherein the plurality of magnetic nanoparticles are superparamagnetic. [0139] Embodiment 8. The supercluster of any one of embodiments 1-7, wherein the plurality of magnetic nanoparticles are nanospheres. [0140] Embodiment 9. The supercluster of embodiment 8, wherein the nanospheres have a size of less than or equal to 35 nm. [0141] Embodiment 10. The supercluster of embodiment 8, wherein the nanospheres have a size of 9 nm to 31 nm. [0142] Embodiment 11. The supercluster of any one of embodiments 1-7, wherein the plurality of magnetic nanoparticles are nanocubes. [0143] Embodiment 12. The supercluster of embodiment 11, wherein the nanocubes have a size of less than or equal to 25 nm. [0144] Embodiment 13. The supercluster of embodiment 11, wherein the nanocubes have a size of 9 nm to 20 nm. [0145] Embodiment 14. The supercluster of any one of embodiments 1-13, wherein the supercluster has a size of less than or equal to 300 nm. [0146] Embodiment 15. The supercluster of any one of embodiments 1-13, wherein the supercluster has a size of 289 nm to 187 nm. [0147] Embodiment 16. The supercluster of any one of embodiments 1-15, wherein the supercluster is a magnetic supercluster. [0148] Embodiment 17. The supercluster of any one of embodiments 1-16, wherein the supercluster is a supercluster particle. [0149] Embodiment 18. A method of producing the supercluster of any one of embodiments 1-17, the method comprising: providing a nanoparticle colloidal solution, wherein the nanoparticle colloidal solution comprises a plurality of magnetic nanoparticles; providing an ^{4913-4975-3383.1} Page 60 of 144 094876-000024WOPT aqueous dodecyltrimethylammonium bromide (DTAB) solution; contacting the nanoparticle colloidal solution with the aqueous DTAB solution to provide a mixture; mixing the mixture; heating the mixture; and collecting the supercluster. [0150] Embodiment 19. The method of embodiment 18, wherein the step of mixing the mixture is carried out by vortexing the mixture. [0151] Embodiment 20. The method of embodiment 18 or embodiment 19, wherein the plurality of magnetic nanoparticles are nanospheres. [0152] Embodiment 21. The method of embodiment 18 or embodiment 19, wherein the plurality of magnetic nanoparticles are nanocubes. [0153] Embodiment 22. A supercluster made by the method of any one of embodiments 18-21. [0154] Embodiment 23. Use of a supercluster of any one of embodiments 1-17. [0155] Additional embodiments include those listed below. [0156] Embodiment 24. A magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0157] Embodiment 25. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle has a spherical shape or a cubic shape. [0158] Embodiment 26. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle is a nanosphere or a nanocube. [0159] Embodiment 27. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle independently has a particle size of at least 12 nm. [0160] Embodiment 28. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle independently has a particle size of 12 nm to 30 nm. [0161] Embodiment 29. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle independently has a particle size of at least 20 nm. ^{4913-4975-3383.1} Page 61 of 144 094876-000024WOPT [0162] Embodiment 30. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle independently has a particle size of 20 nm to 30 nm. [0163] Embodiment 31. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a particle size of at least 15 nm. [0164] Embodiment 32. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a particle size of 15 nm to 25 nm. [0165] Embodiment 33. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a particle size of at least 20 nm. [0166] Embodiment 34. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a particle size of 20 nm to 25 nm. [0167] Embodiment 35. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a particle size of at least 12 nm. [0168] Embodiment 36. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a particle size of 12 nm to 30 nm. [0169] Embodiment 37. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a particle size of at least 20 nm. [0170] Embodiment 38. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a particle size of 20 nm to 30 nm. [0171] Embodiment 39. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a diameter of at least 120 nm. [0172] Embodiment 40. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a diameter of 120 nm to 400 nm. [0173] Embodiment 41. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a diameter of at least 200 nm. [0174] Embodiment 42. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a diameter of 200 nm to 400 nm. [0175] Embodiment 43. The magnetic supercluster particle of embodiment 24, wherein the intermolecular interaction comprises Van der Waals force. [0176] Embodiment 44. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle is superparamagnetic. ^{4913-4975-3383.1} Page 62 of 144 094876-000024WOPT [0177] Embodiment 45. The magnetic supercluster particle of embodiment 24, wherein the plurality of magnetic nanoparticles is superparamagnetic. [0178] Embodiment 46. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle is superparamagnetic. [0179] Embodiment 47. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle individually has a saturation magnetization (Ms) value of at least 33 emu/g at an applied field of 4 Tesla (T). [0180] Embodiment 48. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle individually has a saturation magnetization (Ms) value of 33 emu/g to 60 emu/g at an applied field of 4 Tesla (T). [0181] Embodiment 49. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a saturation magnetization (Ms) value of at least 45 emu/g at an applied field of 4 Tesla (T). [0182] Embodiment 50. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a saturation magnetization (Ms) value of 45 emu/g to 60 emu/g at an applied field of 4 Tesla (T). [0183] Embodiment 51. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a saturation magnetization (Ms) value of at least 33 emu/g at an applied field of 4 Tesla (T). [0184] Embodiment 52. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a saturation magnetization (Ms) value of 33 emu/g to 60 emu/g at an applied field of 4 Tesla (T). [0185] Embodiment 53. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle individually has a blocking temperature (T_B) of at least 215 Kelvin (K). [0186] Embodiment 54. The magnetic supercluster particle of embodiment 24, wherein each magnetic nanoparticle individually has a blocking temperature (T_B) of 215 Kelvin (K) to 300 Kelvin (K). [0187] Embodiment 55. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a blocking temperature (T_B) of at least 270 Kelvin (K). ^{4913-4975-3383.1} Page 63 of 144 094876-000024WOPT [0188] Embodiment 56. The magnetic supercluster particle of embodiment 26, wherein the nanocube has a blocking temperature (T_B) of 270 Kelvin (K) to 300 Kelvin (K). [0189] Embodiment 57. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a blocking temperature (T_B) of at least 215 Kelvin (K). [0190] Embodiment 58. The magnetic supercluster particle of embodiment 26, wherein the nanosphere has a blocking temperature (T_B) of 215 Kelvin (K) to 300 Kelvin (K). [0191] Embodiment 59 The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T). [0192] Embodiment 60. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a saturation magnetization (Ms) value of 48 emu/g to 60 emu/g at a magnetic field of 4 Tesla (T). [0193] Embodiment 61. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a blocking temperature (T_B) of at least 220 Kelvin (K). [0194] Embodiment 62. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a blocking temperature (T_B) of 220 Kelvin (K) to 310 Kelvin (K). [0195] Embodiment 63. An article of manufacture, comprising at least one magnetic supercluster particle of any one of embodiments 24-62. [0196] Embodiment 64. A magnetic resonance imaging (MRI) contrast agent, comprising at least one magnetic supercluster particle of any one of embodiments 24-62. [0197] Embodiment 65. A magnetic resonance imaging (MRI) probe, comprising at least one magnetic supercluster particle of any one of embodiments 24-62. [0198] Embodiment 66. A sensor, comprising at least one magnetic supercluster particle of any one of embodiments 24-62. [0199] Embodiment 67. The sensor of embodiment 66, wherein the sensor is a biosensor. [0200] Embodiment 68. An article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one magnetic supercluster particle of any one of embodiments 24-62. [0201] Embodiment 69. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has superparamagnetic properties. ^{4913-4975-3383.1} Page 64 of 144 094876-000024WOPT [0202] Embodiment 70. The magnetic supercluster particle of embodiment 69, wherein the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle. [0203] Embodiment 71. The magnetic supercluster particle of embodiment 69, wherein the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle. [0204] Embodiment 72. The magnetic supercluster particle of embodiment 69, wherein the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle. [0205] Embodiment 73. The magnetic supercluster particle of embodiment 69, wherein the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of the plurality of magnetic nanoparticles. [0206] Embodiment 74. The magnetic supercluster particle of embodiment 69, wherein the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of the plurality of magnetic nanoparticles. [0207] Embodiment 75. The magnetic supercluster particle of embodiment 69, wherein the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of the plurality of magnetic nanoparticles. [0208] Embodiment 76. The magnetic supercluster particle of embodiment 24, wherein at least one property of the magnetic supercluster particle is controlled by at least one property of each magnetic nanoparticle. [0209] Embodiment 77. The magnetic supercluster particle of embodiment 76, wherein the at least one property of the magnetic supercluster particle is at least one magnetic property of the magnetic supercluster particle. [0210] Embodiment 78. The magnetic supercluster particle of embodiment 76, wherein the at least one property of the magnetic supercluster particle is at least one superparamagnetic property of the magnetic supercluster particle [0211] Embodiment 79. The magnetic supercluster particle of embodiment 76, wherein the at least one property of the magnetic supercluster particle is saturation magnetization (Ms) or blocking temperature (T_B). ^{4913-4975-3383.1} Page 65 of 144 094876-000024WOPT [0212] Embodiment 80. The magnetic supercluster particle of embodiment 76, wherein the at least one property of each magnetic nanoparticle is at least one magnetic property of each magnetic nanoparticle. [0213] Embodiment 81. The magnetic supercluster particle of embodiment 76, wherein the at least one property of each magnetic nanoparticle is at least one superparamagnetic property of each magnetic nanoparticle. [0214] Embodiment 82. The magnetic supercluster particle of embodiment 76, wherein the at least one property of each magnetic nanoparticle is saturation magnetization (Ms) or blocking temperature (T_B). [0215] Embodiment 83. The magnetic supercluster particle of embodiment 76, wherein the at least one property of each magnetic nanoparticle is a particle size of each magnetic nanoparticle, or a shape of each magnetic nanoparticle, or combination thereof. [0216] Embodiment 84. The magnetic supercluster particle of embodiment 24, wherein at least one property of the magnetic supercluster particle is controlled by at least one property of the plurality of magnetic nanoparticles. [0217] Embodiment 85. The magnetic supercluster particle of embodiment 24, wherein at least one property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0218] Embodiment 86. The magnetic supercluster particle of embodiment 85, wherein the greater the amount of FeO in the core of each magnetic nanoparticle the larger a particle size of each magnetic nanoparticle. [0219] Embodiment 87. The magnetic supercluster particle of embodiment 85, wherein the at least one property of the magnetic supercluster particle is at least one magnetic property of the magnetic supercluster particle. [0220] Embodiment 88. The magnetic supercluster particle of embodiment 85, wherein the at least one property of the magnetic supercluster particle is at least one superparamagnetic property of the magnetic supercluster particle. [0221] Embodiment 89. The magnetic supercluster particle of embodiment 85, wherein the at least one property of the magnetic supercluster particle is saturation magnetization (Ms) or blocking temperature (T_B). ^{4913-4975-3383.1} Page 66 of 144 094876-000024WOPT [0222] Embodiment 90. The magnetic supercluster particle of embodiment 85, wherein the at least one property of the magnetic supercluster is a particle size of each magnetic nanoparticle. [0223] Embodiment 91. The magnetic supercluster particle of embodiment 24, wherein the magnetic supercluster particle has a saturation magnetization (Ms) value of 48 emu/g to 72 emu/g at a magnetic field of 4 Tesla (T). [0224] Additional embodiments include those listed below. [0225] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0226] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0227] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0228] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. ^{4913-4975-3383.1} Page 67 of 144 094876-000024WOPT [0229] In some embodiments, the supercluster further comprises dodecyltrimethylammonium bromide (DTAB). [0230] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0231] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0232] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non- covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0233] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0234] In some embodiments, each magnetic nanoparticle is a magnetic nanoparticle of the plurality of magnetic nanoparticles. ^{4913-4975-3383.1} Page 68 of 144 094876-000024WOPT [0235] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0236] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0237] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0238] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0239] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. ^{4913-4975-3383.1} Page 69 of 144 094876-000024WOPT [0240] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0241] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non- covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0242] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0243] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0244] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO ^{4913-4975-3383.1} Page 70 of 144 094876-000024WOPT and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0245] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0246] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0247] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0248] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and ^{4913-4975-3383.1} Page 71 of 144 094876-000024WOPT wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0249] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0250] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles. [0251] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0252] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with ^{4913-4975-3383.1} Page 72 of 144 094876-000024WOPT at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0253] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0254] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0255] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0256] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and ^{4913-4975-3383.1} Page 73 of 144 094876-000024WOPT wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0257] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0258] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles through an intermolecular interaction. [0259] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0260] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic ^{4913-4975-3383.1} Page 74 of 144 094876-000024WOPT nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0261] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0262] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0263] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0264] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein ^{4913-4975-3383.1} Page 75 of 144 094876-000024WOPT the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0265] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0266] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0267] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster through an intermolecular interaction. [0268] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of ^{4913-4975-3383.1} Page 76 of 144 094876-000024WOPT magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster through an intermolecular interaction. [0269] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster through an intermolecular interaction. [0270] In various embodiments, the present invention provides a supercluster, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster through an intermolecular interaction. [0271] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. ^{4913-4975-3383.1} Page 77 of 144 094876-000024WOPT [0272] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0273] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0274] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0275] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each ^{4913-4975-3383.1} Page 78 of 144 094876-000024WOPT magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0276] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0277] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0278] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster. [0279] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0280] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is ^{4913-4975-3383.1} Page 79 of 144 094876-000024WOPT non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0281] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non- covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0282] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle. [0283] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0284] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0285] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one ^{4913-4975-3383.1} Page 80 of 144 094876-000024WOPT oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0286] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the supercluster is non-covalently associated with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0287] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0288] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0289] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non- covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. ^{4913-4975-3383.1} Page 81 of 144 094876-000024WOPT [0290] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0291] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster through an intermolecular interaction. [0292] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster through an intermolecular interaction. [0293] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non-covalently associated with at least one other ^{4913-4975-3383.1} Page 82 of 144 094876-000024WOPT magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster through an intermolecular interaction. [0294] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster through an intermolecular interaction. [0295] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0296] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0297] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein ^{4913-4975-3383.1} Page 83 of 144 094876-000024WOPT the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0298] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non- covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle through an intermolecular interaction. [0299] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster. [0300] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non- covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster. [0301] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two ^{4913-4975-3383.1} Page 84 of 144 094876-000024WOPT magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster. [0302] In various embodiments, the present invention provides a supercluster, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the supercluster. [0303] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle. [0304] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein the shell of each magnetic nanoparticle of the at least two magnetic nanoparticles is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle. [0305] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein ^{4913-4975-3383.1} Page 85 of 144 094876-000024WOPT the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle. [0306] In various embodiments, the present invention provides a magnetic supercluster particle, comprising: at least two magnetic nanoparticles; wherein each magnetic nanoparticle of the at least two magnetic nanoparticles comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein at least one oleic acid capping agent is attached to at least a portion of the shell of each magnetic nanoparticle; and wherein each magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle is non- covalently associated with at least one other magnetic nanoparticle of the at least two magnetic nanoparticles in the magnetic supercluster particle. [0307] In some embodiments, a supercluster is a supercluster particle. In some embodiments, a supercluster is a magnetic supercluster. In some embodiments, a supercluster is a magnetic supercluster particle. In some embodiments, a supercluster particle is a magnetic supercluster particle. In some embodiments, a supercluster is a superparamagnetic supercluster. In some embodiments, a supercluster is a superparamagnetic supercluster particle. In some embodiments, a superparamagnetic supercluster is a superparamagnetic supercluster particle. [0308] In some embodiments, the magnetic nanoparticle in the supercluster is non- covalently bonded with at least one other magnetic nanoparticle in the supercluster. In some embodiments, the magnetic nanoparticle in the supercluster is non-covalently bonded with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. In some embodiments, each magnetic nanoparticle in the supercluster is non-covalently bonded with at least one other magnetic nanoparticle in the supercluster. In some embodiments, each magnetic nanoparticle in the supercluster is non-covalently bonded with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0309] In some embodiments, the magnetic nanoparticle in the magnetic supercluster particle is non-covalently bonded with at least one other magnetic nanoparticle in the magnetic supercluster particle. In some embodiments, the magnetic nanoparticle in the magnetic supercluster particle is non-covalently bonded with at least one other magnetic nanoparticle in the ^{4913-4975-3383.1} Page 86 of 144 094876-000024WOPT magnetic supercluster particle through an intermolecular interaction. In some embodiments, each magnetic nanoparticle in the magnetic supercluster particle is non-covalently bonded with at least one other magnetic nanoparticle in the magnetic supercluster particle. In some embodiments, each magnetic nanoparticle in the magnetic supercluster particle is non-covalently bonded with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0310] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non-covalently bonded with at least one other magnetic nanoparticle in the supercluster. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster is non-covalently bonded with at least one other magnetic nanoparticle in the supercluster through an intermolecular interaction. [0311] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non-covalently bonded with at least one other magnetic nanoparticle in the magnetic supercluster particle. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle is non- covalently bonded with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0312] In some embodiments, each magnetic nanoparticle has a spherical shape or a cubic shape. In some embodiments, each magnetic nanoparticle independently has a spherical shape or a cubic shape. In some embodiments, each magnetic nanoparticle has a spherical shape, or a cubic shape, or any combination thereof. In some embodiments, each magnetic nanoparticle has a spherical shape. In some embodiments, each magnetic nanoparticle has a cubic shape. [0313] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has a spherical shape or a cubic shape. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a spherical shape or a cubic shape. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has a spherical shape, or a cubic shape, or any combination thereof. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has a spherical shape. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has a cubic shape. ^{4913-4975-3383.1} Page 87 of 144 094876-000024WOPT [0314] In some embodiments, each magnetic nanoparticle is a nanosphere or a nanocube. In some embodiments, each magnetic nanoparticle is independently a nanosphere or a nanocube. In some embodiments, each magnetic nanoparticle is a nanosphere, or a nanocube, or any combination thereof. In some embodiments, each magnetic nanoparticle is a nanosphere. In some embodiments, each magnetic nanoparticle is a nanocube. [0315] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is a nanosphere or a nanocube. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is independently a nanosphere or a nanocube. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is a nanosphere, or a nanocube, or any combination thereof. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is a nanosphere. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is a nanocube. [0316] In some embodiments, each magnetic nanoparticle independently has a particle size of at least 12 nm. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a particle size of at least 12 nm. [0317] In some embodiments, each magnetic nanoparticle independently has a particle size of 12 nm to 30 nm. In some embodiments, each magnetic nanoparticle independently has a particle size of 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or any range thereof. [0318] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a particle size of 12 nm to 30 nm. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a particle size of 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or any range thereof. [0319] In some embodiments, each magnetic nanoparticle independently has a particle size of at least 20 nm. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a particle size of at least 20 nm. [0320] In some embodiments, each magnetic nanoparticle independently has a particle size of 20 nm to 30 nm. In some embodiments, each magnetic nanoparticle independently has a particle size of 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or any range thereof. ^{4913-4975-3383.1} Page 88 of 144 094876-000024WOPT [0321] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a particle size of 20 nm to 30 nm. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles independently has a particle size of 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or any range thereof. [0322] In some embodiments, the nanocube has a particle size of at least 15 nm. [0323] In some embodiments, the nanocube has a particle size of 15 nm to 25 nm. In some embodiments, the nanocube has a particle size of 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, or 25 nm, or any range thereof. [0324] In some embodiments, the nanocube has a particle size of at least 20 nm. [0325] In some embodiments, the nanocube has a particle size of 20 nm to 25 nm. In some embodiments, the nanocube has a particle size of 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, or 25 nm, or any range thereof. [0326] In some embodiments, the nanosphere has a particle size of at least 12 nm. [0327] In some embodiments, the nanosphere has a particle size of 12 nm to 30 nm. In some embodiments, the nanosphere has a particle size of 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or any range thereof. [0328] In some embodiments, the nanosphere has a particle size of at least 20 nm. [0329] In some embodiments, the nanosphere has a particle size of 20 nm to 30 nm. In some embodiments, the nanosphere has a particle size of 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or any range thereof. [0330] In some embodiments, the supercluster has a diameter of at least 120 nm. In some embodiments, the magnetic supercluster particle has a diameter of at least 120 nm. [0331] In some embodiments, the magnetic supercluster particle has a diameter of 120 nm to 400 nm. In some embodiments, the magnetic supercluster particle has a diameter of 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, or 400 nm, or any range thereof. [0332] In some embodiments, the supercluster has a diameter of 120 nm to 400 nm. In some embodiments, the magnetic supercluster particle has a diameter of 120 nm, 130 nm, 140 nm, ^{4913-4975-3383.1} Page 89 of 144 094876-000024WOPT 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, or 400 nm, or any range thereof. [0333] In some embodiments, the magnetic supercluster particle has a diameter of at least 200 nm. In some embodiments, the supercluster has a diameter of at least 200 nm. [0334] In some embodiments, the magnetic supercluster particle has a diameter of 200 nm to 400 nm. In some embodiments, the magnetic supercluster particle has a diameter of 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, or 400 nm, or any range thereof. [0335] In some embodiments, the supercluster has a diameter of 200 nm to 400 nm. In some embodiments, the supercluster has a diameter of 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, or 400 nm, or any range thereof. [0336] In some embodiments, the intermolecular interaction comprises Van der Waals force. In some embodiments, the intermolecular interaction is Van der Waals force. [0337] In some embodiments, each magnetic nanoparticle is superparamagnetic. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is superparamagnetic. [0338] In some embodiments, the plurality of magnetic nanoparticles is superparamagnetic. [0339] In some embodiments, the at least two magnetic nanoparticles are superparamagnetic. In some embodiments, each magnetic nanoparticle of the at least two magnetic nanoparticles are superparamagnetic. [0340] In some embodiments, the magnetic supercluster particle is superparamagnetic. In some embodiments, the supercluster is superparamagnetic. [0341] In some embodiments, each magnetic nanoparticle individually has a saturation magnetization (Ms) value of at least 33 emu/g at an applied field of 4 Tesla (T). In some embodiments, each magnetic nanoparticle of the plurality individually has a saturation magnetization (Ms) value of at least 33 emu/g at an applied field of 4 Tesla (T). ^{4913-4975-3383.1} Page 90 of 144 094876-000024WOPT [0342] In some embodiments, each magnetic nanoparticle individually has a saturation magnetization (Ms) value of 33 emu/g to 60 emu/g at an applied field of 4 Tesla (T). In some embodiments, each magnetic nanoparticle individually has a saturation magnetization (Ms) value of 33 emu/g, 34 emu/g, 35 emu/g, 36 emu/g, 37 emu/g, 38 emu/g, 39 emu/g, 40 emu/g, 41 emu/g, 42 emu/g, 43 emu/g, 44 emu/g, 45 emu/g, 46 emu/g, 47 emu/g, 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, or 60 emu/g at an applied field of 4 Tesla (T), or any range thereof [0343] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles individually has a saturation magnetization (Ms) value of 33 emu/g to 60 emu/g at an applied field of 4 Tesla (T). In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles individually has a saturation magnetization (Ms) value of 33 emu/g, 34 emu/g, 35 emu/g, 36 emu/g, 37 emu/g, 38 emu/g, 39 emu/g, 40 emu/g, 41 emu/g, 42 emu/g, 43 emu/g, 44 emu/g, 45 emu/g, 46 emu/g, 47 emu/g, 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, or 60 emu/g at an applied field of 4 Tesla (T), or any range thereof. [0344] In some embodiments, the nanocube has a saturation magnetization (Ms) value of at least 45 emu/g at an applied field of 4 Tesla (T). [0345] In some embodiments, the nanocube has a saturation magnetization (Ms) value of 45 emu/g to 60 emu/g at an applied field of 4 Tesla (T). In some embodiments, the nanocube has a saturation magnetization (Ms) value of 45 emu/g, 46 emu/g, 47 emu/g, 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, or 60 emu/g at an applied field of 4 Tesla (T), or any range thereof. [0346] In some embodiments, the nanosphere has a saturation magnetization (Ms) value of at least 33 emu/g at an applied field of 4 Tesla (T). [0347] In some embodiments, the nanosphere has a saturation magnetization (Ms) value of 33 emu/g to 60 emu/g at an applied field of 4 Tesla (T). In some embodiments, the nanosphere has a saturation magnetization (Ms) value of 33 emu/g, 34 emu/g, 35 emu/g, 36 emu/g, 37 emu/g, 38 emu/g, 39 emu/g, 40 emu/g, 41 emu/g, 42 emu/g, 43 emu/g, 44 emu/g, 45 emu/g, 46 emu/g, 47 emu/g, 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, or 60 emu/g at an applied field of 4 Tesla (T), or any range thereof ^{4913-4975-3383.1} Page 91 of 144 094876-000024WOPT [0348] In some embodiments, each magnetic nanoparticle individually has a blocking temperature (T_B) of at least 215 Kelvin (K). In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles individually has a blocking temperature (T_B) of at least 215 Kelvin (K). [0349] In some embodiments, each magnetic nanoparticle individually has a blocking temperature (T_B) of 215 Kelvin (K) to 300 Kelvin (K). In some embodiments, each magnetic nanoparticle individually has a blocking temperature (T_B) of 215 Kelvin (K), 220 Kelvin (K), 225 Kelvin (K), 230 Kelvin (K), 235 Kelvin (K), 240 Kelvin (K), 245 Kelvin (K), 250 Kelvin (K), 255 Kelvin (K), 260 Kelvin (K), 265 Kelvin (K), 270 Kelvin (K), 275 Kelvin (K), 280 Kelvin (K), 285 Kelvin (K), 290 Kelvin (K), 295 Kelvin (K), or 300 Kelvin (K), or any range thereof [0350] In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles individually has a blocking temperature (T_B) of 215 Kelvin (K) to 300 Kelvin (K). In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles individually has a blocking temperature (T_B) of 215 Kelvin (K), 220 Kelvin (K), 225 Kelvin (K), 230 Kelvin (K), 235 Kelvin (K), 240 Kelvin (K), 245 Kelvin (K), 250 Kelvin (K), 255 Kelvin (K), 260 Kelvin (K), 265 Kelvin (K), 270 Kelvin (K), 275 Kelvin (K), 280 Kelvin (K), 285 Kelvin (K), 290 Kelvin (K), 295 Kelvin (K), or 300 Kelvin (K), or any range thereof [0351] In some embodiments, the nanocube has a blocking temperature (T_B) of at least 270 Kelvin (K). [0352] In some embodiments, the nanocube has a blocking temperature (T_B) of 270 Kelvin (K) to 300 Kelvin (K). In some embodiments, the nanocube has a blocking temperature (T_B) of 270 Kelvin (K), 275 Kelvin (K), 280 Kelvin (K), 285 Kelvin (K), 290 Kelvin (K), 295 Kelvin (K), or 300 Kelvin (K), or any range thereof [0353] In some embodiments, the nanosphere has a blocking temperature (T_B) of at least 215 Kelvin (K). [0354] In some embodiments, the nanosphere has a blocking temperature (T_B) of 215 Kelvin (K) to 300 Kelvin (K). In some embodiments, the nanosphere has a blocking temperature (T_B) of 215 Kelvin (K), 220 Kelvin (K), 225 Kelvin (K), 230 Kelvin (K), 235 Kelvin (K), 240 Kelvin (K), 245 Kelvin (K), 250 Kelvin (K), 255 Kelvin (K), 260 Kelvin (K), 265 Kelvin (K), 270 Kelvin (K), 275 Kelvin (K), 280 Kelvin (K), 285 Kelvin (K), 290 Kelvin (K), 295 Kelvin (K), or 300 Kelvin (K), or any range thereof ^{4913-4975-3383.1} Page 92 of 144 094876-000024WOPT [0355] In some embodiments, the magnetic supercluster particle has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T). In some embodiments, the supercluster has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T). [0356] In some embodiments, the magnetic supercluster particle has a saturation magnetization (Ms) value of 48 emu/g to 60 emu/g at a magnetic field of 4 Tesla (T). In some embodiments, the magnetic supercluster particle has a saturation magnetization (Ms) value of 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, or 60 emu/g at a magnetic field of 4 Tesla (T), or any range thereof. [0357] In some embodiments, the supercluster has a saturation magnetization (Ms) value of 48 emu/g to 60 emu/g at a magnetic field of 4 Tesla (T). In some embodiments, the supercluster has a saturation magnetization (Ms) value of 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, or 60 emu/g at a magnetic field of 4 Tesla (T), or any range thereof. [0358] In some embodiments, the magnetic supercluster particle has a blocking temperature (T_B) of at least 220 Kelvin (K). In some embodiments, the supercluster has a blocking temperature (T_B) of at least 220 Kelvin (K). [0359] In some embodiments, the magnetic supercluster particle has a blocking temperature (T_B) of 220 Kelvin (K) to 310 Kelvin (K). In some embodiments, the magnetic supercluster particle has a blocking temperature (T_B) of 220 Kelvin (K), 220 Kelvin (K), 225 Kelvin (K), 230 Kelvin (K), 235 Kelvin (K), 240 Kelvin (K), 245 Kelvin (K), 250 Kelvin (K), 255 Kelvin (K), 260 Kelvin (K), 265 Kelvin (K), 270 Kelvin (K), 275 Kelvin (K), 280 Kelvin (K), 285 Kelvin (K), 290 Kelvin (K), 295 Kelvin (K), 300 Kelvin (K), or 310 Kelvin (K), or any range thereof. [0360] In some embodiments, the supercluster has a blocking temperature (T_B) of 220 Kelvin (K) to 310 Kelvin (K). In some embodiments, the supercluster has a blocking temperature (T_B) of 220 Kelvin (K), 220 Kelvin (K), 225 Kelvin (K), 230 Kelvin (K), 235 Kelvin (K), 240 Kelvin (K), 245 Kelvin (K), 250 Kelvin (K), 255 Kelvin (K), 260 Kelvin (K), 265 Kelvin (K), 270 Kelvin (K), 275 Kelvin (K), 280 Kelvin (K), 285 Kelvin (K), 290 Kelvin (K), 295 Kelvin (K), 300 Kelvin (K), or 310 Kelvin (K), or any range thereof. ^{4913-4975-3383.1} Page 93 of 144 094876-000024WOPT [0361] In various embodiments, the present invention provides an article of manufacture, comprising at least one magnetic supercluster particle of the present invention described herein. In various embodiments, the present invention provides an article of manufacture, comprising at least one supercluster of the present invention described herein. [0362] In various embodiments, the present invention provides a magnetic resonance imaging (MRI) contrast agent, comprising at least one magnetic supercluster particle of the present invention described herein. In various embodiments, the present invention provides a magnetic resonance imaging (MRI) contrast agent, comprising at least one supercluster of the present invention described herein. [0363] In various embodiments, the present invention provides a magnetic resonance imaging (MRI) probe, comprising at least one magnetic supercluster particle of the present invention described herein. In various embodiments, the present invention provides a magnetic resonance imaging (MRI) probe, comprising at least one supercluster of the present invention described herein. [0364] In various embodiments, the present invention provides a sensor, comprising at least one magnetic supercluster particle of the present invention described herein. In some embodiments, the sensor is a biosensor. In various embodiments, the present invention provides a sensor, comprising at least one supercluster of the present invention described herein. In some embodiments, the sensor is a biosensor. [0365] In some embodiments, the present invention provides an article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one magnetic supercluster particle of the present invention as described in herein. [0366] In some embodiments, the present invention provides an article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one supercluster of the present invention as described in herein. [0367] In some embodiments, the present invention provides an article of manufacture suitable for drug delivery, wherein the article of manufacture comprises at least one magnetic supercluster particle of the present invention as described in herein. [0368] In some embodiments, the present invention provides an article of manufacture suitable for drug delivery, wherein the article of manufacture comprises at least one supercluster of the present invention as described in herein. ^{4913-4975-3383.1} Page 94 of 144 094876-000024WOPT [0369] In some embodiments, the present invention provides a drug delivery device comprising at least one magnetic supercluster particle of the present invention. In some embodiments, the present invention provides a drug delivery device comprising at least one supercluster of the present invention. [0370] In some embodiments, the magnetic supercluster particle has magnetic properties. In some embodiments, the magnetic supercluster particle has superparamagnetic properties. In some embodiments, the magnetic supercluster particle is superparamagnetic. In some embodiments, the magnetic supercluster particle has at least one magnetic property. In some embodiments, the magnetic supercluster particle has at least one superparamagnetic property. [0371] In some embodiments, the supercluster has magnetic properties. In some embodiments, the supercluster has superparamagnetic properties. In some embodiments, the supercluster is superparamagnetic. In some embodiments, the supercluster has at least one magnetic property. In some embodiments, the supercluster has at least one superparamagnetic property. [0372] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. [0373] In some embodiments, the superparamagnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle in the supercluster. [0374] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. [0375] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle. In some ^{4913-4975-3383.1} Page 95 of 144 094876-000024WOPT embodiments, at least one superparamagnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle in the supercluster. [0376] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0377] In some embodiments, the superparamagnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0378] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0379] In some embodiments, at least one superparamagnetic property of supercluster is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0380] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. [0381] In some embodiments, the magnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, the magnetic ^{4913-4975-3383.1} Page 96 of 144 094876-000024WOPT properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle in the supercluster. [0382] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. [0383] In some embodiments, at least one magnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle. In some embodiments, at least one magnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle in the supercluster. [0384] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0385] In some embodiments, the magnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0386] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0387] In some embodiments, at least one magnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the supercluster is controlled by at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. ^{4913-4975-3383.1} Page 97 of 144 094876-000024WOPT [0388] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle in the magnetic supercluster particle. [0389] In some embodiments, the superparamagnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle in the supercluster. [0390] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle in the magnetic supercluster particle. [0391] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle in the supercluster. [0392] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle in the magnetic supercluster particle. [0393] In some embodiments, the magnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle. In some embodiments, the magnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle in the supercluster. [0394] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle in the magnetic supercluster particle. [0395] In some embodiments, at least one magnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle. In some embodiments, at least one magnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle in the supercluster. ^{4913-4975-3383.1} Page 98 of 144 094876-000024WOPT [0396] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0397] In some embodiments, the magnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0398] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0399] In some embodiments, at least one magnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0400] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0401] In some embodiments, the superparamagnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0402] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle of the plurality ^{4913-4975-3383.1} Page 99 of 144 094876-000024WOPT of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0403] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0404] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle in the magnetic supercluster particle. [0405] In some embodiments, the superparamagnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle in the supercluster. [0406] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle in the magnetic supercluster particle. [0407] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle in the supercluster. [0408] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0409] In some embodiments, the superparamagnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In ^{4913-4975-3383.1} Page 100 of 144 094876-000024WOPT some embodiments, the superparamagnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0410] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0411] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0412] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle in the magnetic supercluster particle. [0413] In some embodiments, the magnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle. In some embodiments, the magnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle in the supercluster. [0414] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle in the magnetic supercluster particle. [0415] In some embodiments, at least one magnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle. In some embodiments, at least one magnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle in the supercluster. [0416] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. ^{4913-4975-3383.1} Page 101 of 144 094876-000024WOPT [0417] In some embodiments, the magnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0418] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0419] In some embodiments, at least one magnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the supercluster is controlled by a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0420] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0421] In some embodiments, the superparamagnetic properties of the supercluster are controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the supercluster. [0422] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0423] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the supercluster. ^{4913-4975-3383.1} Page 102 of 144 094876-000024WOPT [0424] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0425] In some embodiments, the magnetic properties of the supercluster are controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the supercluster. [0426] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0427] In some embodiments, at least one magnetic property of the supercluster is controlled by at least one magnetic property of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the supercluster is controlled by at least one magnetic property of the plurality of magnetic nanoparticles in the supercluster. [0428] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a particle size of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0429] In some embodiments, the superparamagnetic properties of the supercluster are controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by a particle size of the plurality of magnetic nanoparticles in the supercluster. [0430] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle ^{4913-4975-3383.1} Page 103 of 144 094876-000024WOPT is controlled by a particle size of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0431] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a particle size of the plurality of magnetic nanoparticles in the supercluster. [0432] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a particle size of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0433] In some embodiments, the magnetic properties of the supercluster are controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by a particle size of the plurality of magnetic nanoparticles in the supercluster. [0434] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a particle size of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0435] In some embodiments, at least one magnetic property of the supercluster is controlled by a particle size of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the supercluster is controlled by a particle size of the plurality of magnetic nanoparticles in the supercluster. [0436] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by a shape of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0437] In some embodiments, the superparamagnetic properties of the supercluster are controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by a shape of the plurality of magnetic nanoparticles in the supercluster. ^{4913-4975-3383.1} Page 104 of 144 094876-000024WOPT [0438] In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the magnetic supercluster particle is controlled by a shape of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0439] In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, at least one superparamagnetic property of the supercluster is controlled by a shape of the plurality of magnetic nanoparticles in the supercluster. [0440] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by a shape of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0441] In some embodiments, the magnetic properties of the supercluster are controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by a shape of the plurality of magnetic nanoparticles in the supercluster. [0442] In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the magnetic supercluster particle is controlled by a shape of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0443] In some embodiments, at least one magnetic property of the supercluster is controlled by a shape of the plurality of magnetic nanoparticles. In some embodiments, at least one magnetic property of the supercluster is controlled by a shape of the plurality of magnetic nanoparticles in the supercluster. [0444] In some embodiments, at least one property of the magnetic supercluster particle is controlled by at least one property of each magnetic nanoparticle. In some embodiments, at least one property of the magnetic supercluster particle is controlled by at least one property of each magnetic nanoparticle in the magnetic supercluster particle. [0445] In some embodiments, at least one property of the supercluster is controlled by at least one property of each magnetic nanoparticle. In some embodiments, at least one property of ^{4913-4975-3383.1} Page 105 of 144 094876-000024WOPT the supercluster is controlled by at least one property of each magnetic nanoparticle in the supercluster. [0446] In some embodiments, at least one property of the magnetic supercluster particle is controlled by at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one property of the magnetic supercluster particle is controlled by at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the magnetic supercluster particle. [0447] In some embodiments, at least one property of the supercluster is controlled by at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, at least one property of the supercluster is controlled by at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles in the supercluster. [0448] In some embodiments, the at least one property of the magnetic supercluster particle is at least one magnetic property of the magnetic supercluster particle. [0449] In some embodiments, the at least one property of the supercluster is at least one magnetic property of the supercluster. [0450] In some embodiments, the at least one property of the magnetic supercluster particle is at least one superparamagnetic property of the magnetic supercluster particle. [0451] In some embodiments, the at least one property of the supercluster is at least one superparamagnetic property of the supercluster. [0452] In some embodiments, the magnetic properties of the magnetic supercluster particle are saturation magnetization (Ms) and/or blocking temperature (T_B). [0453] In some embodiments, the magnetic properties of the supercluster are saturation magnetization (Ms) and/or blocking temperature (T_B). [0454] In some embodiments, the at least one magnetic property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. In some embodiments, the at least one magnetic property of the magnetic supercluster particle is saturation magnetization (Ms). In some embodiments, the at least one magnetic property of the magnetic supercluster particle is blocking temperature (T_B). [0455] In some embodiments, the at least one magnetic property of the supercluster is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. In some embodiments, the at least one magnetic property of the supercluster is saturation magnetization ^{4913-4975-3383.1} Page 106 of 144 094876-000024WOPT (Ms). In some embodiments, the at least one magnetic property of the supercluster is blocking temperature (T_B). [0456] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are saturation magnetization (Ms) and/or blocking temperature (T_B). [0457] In some embodiments, the superparamagnetic properties of the supercluster are saturation magnetization (Ms) and/or blocking temperature (T_B). [0458] In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is saturation magnetization (Ms). In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is blocking temperature (T_B). [0459] In some embodiments, the at least one superparamagnetic property of the supercluster is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. In some embodiments, the at least one superparamagnetic property of the supercluster is saturation magnetization (Ms). In some embodiments, the at least one superparamagnetic property of the supercluster is blocking temperature (T_B). [0460] In some embodiments, the at least one property of the magnetic supercluster particle is saturation magnetization (Ms) or blocking temperature (T_B). In some embodiments, the at least one property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or a combination thereof. In some embodiments, the at least one property of the magnetic supercluster particle is saturation magnetization (Ms). In some embodiments, the at least one property of the magnetic supercluster particle is blocking temperature (T_B). [0461] In some embodiments, the at least one property of the supercluster is saturation magnetization (Ms) or blocking temperature (T_B). In some embodiments, the at least one property of the supercluster is saturation magnetization (Ms), or blocking temperature (T_B), or a combination thereof. In some embodiments, the at least one property of the supercluster is saturation magnetization (Ms). In some embodiments, the at least one property of the supercluster is blocking temperature (T_B). [0462] In some embodiments, the at least one property of each magnetic nanoparticle is at least one magnetic property of each magnetic nanoparticle. In some embodiments, the at least one ^{4913-4975-3383.1} Page 107 of 144 094876-000024WOPT property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least one magnetic property of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0463] In some embodiments, the at least one property of each magnetic nanoparticle is at least one superparamagnetic property of each magnetic nanoparticle. In some embodiments, the at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is at least one superparamagnetic property of each magnetic nanoparticle. [0464] In some embodiments, the at least one property of each magnetic nanoparticle is saturation magnetization (Ms) or blocking temperature (T_B). In some embodiments, the at least one property of each magnetic nanoparticle is saturation magnetization (Ms), or blocking temperature (T_B), or a combination thereof. In some embodiments, the at least one property of each magnetic nanoparticle is saturation magnetization (Ms). In some embodiments, the at least one property of each magnetic nanoparticle is blocking temperature (T_B). [0465] In some embodiments, the at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is saturation magnetization (Ms) or blocking temperature (T_B). In some embodiments, the at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is saturation magnetization (Ms), or blocking temperature (T_B), or a combination thereof. In some embodiments, the at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is saturation magnetization (Ms). In some embodiments, the at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is blocking temperature (T_B). [0466] In some embodiments, the at least one property of each magnetic nanoparticle is a particle size of each magnetic nanoparticle, or a shape of each magnetic nanoparticle, or combination thereof. In some embodiments, the at least one property of each magnetic nanoparticle is a particle size of each magnetic nanoparticle. In some embodiments, the at least one property of each magnetic nanoparticle is a shape of each magnetic nanoparticle. [0467] In some embodiments, the at least one property of each magnetic nanoparticle is a particle size of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a shape of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or combination thereof. In some embodiments, the at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is a particle size of each magnetic nanoparticle. In some embodiments, the ^{4913-4975-3383.1} Page 108 of 144 094876-000024WOPT at least one property of each magnetic nanoparticle of the plurality of magnetic nanoparticles is a shape of each magnetic nanoparticle. [0468] In some embodiments, the at least one property of the magnetic supercluster particle is controlled by at least one property of the plurality of magnetic nanoparticles. [0469] In some embodiments, the at least one property of the supercluster is controlled by at least one property of the plurality of magnetic nanoparticles. [0470] In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0471] In some embodiments, the at least one property of the supercluster is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one property of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0472] In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some ^{4913-4975-3383.1} Page 109 of 144 094876-000024WOPT embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0473] In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0474] In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0475] In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0476] In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one ^{4913-4975-3383.1} Page 110 of 144 094876-000024WOPT property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one property of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0477] In some embodiments, the at least one property of the supercluster is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the at least one property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one property of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0478] In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one magnetic property of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0479] In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic ^{4913-4975-3383.1} Page 111 of 144 094876-000024WOPT nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one magnetic property of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0480] In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0481] In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the at least one superparamagnetic property of the supercluster is controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the at least one superparamagnetic ^{4913-4975-3383.1} Page 112 of 144 094876-000024WOPT property of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0482] In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0483] In some embodiments, the properties of the supercluster are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the properties of the supercluster are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0484] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0485] In some embodiments, the magnetic properties of the supercluster are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the magnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic ^{4913-4975-3383.1} Page 113 of 144 094876-000024WOPT nanoparticle, or a combination thereof. In some embodiments, the magnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the magnetic properties of the supercluster are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0486] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0487] In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0488] In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the properties of the magnetic supercluster particle are controlled by an ^{4913-4975-3383.1} Page 114 of 144 094876-000024WOPT amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0489] In some embodiments, the properties of the supercluster are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the properties of the supercluster are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0490] In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the magnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the magnetic supercluster particle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0491] In some embodiments, the magnetic properties of the supercluster are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the magnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the magnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some ^{4913-4975-3383.1} Page 115 of 144 094876-000024WOPT embodiments, the magnetic properties of the supercluster is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0492] In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the magnetic supercluster particle are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0493] In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles, or a combination thereof. In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of FeO in the core of each magnetic nanoparticle of the plurality of magnetic nanoparticles. In some embodiments, the superparamagnetic properties of the supercluster are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle of the plurality of magnetic nanoparticles. [0494] In some embodiments, the greater the amount of FeO in the core of each magnetic nanoparticle the larger a particle size of each magnetic nanoparticle. [0495] In some embodiments, the at least one property of the magnetic supercluster particle is at least one magnetic property of the magnetic supercluster particle. In some embodiments, the at least one property of the supercluster is at least one magnetic property of the supercluster. ^{4913-4975-3383.1} Page 116 of 144 094876-000024WOPT [0496] In some embodiments, the at least one property of the magnetic supercluster particle is at least one superparamagnetic property of the magnetic supercluster particle. In some embodiments, the at least one property of the supercluster is at least one superparamagnetic property of the supercluster. [0497] In some embodiments, the at least one property of the magnetic supercluster particle is saturation magnetization (Ms) or blocking temperature (T_B). In some embodiments, the at least one property of the supercluster is saturation magnetization (Ms) or blocking temperature (T_B). [0498] In some embodiments, the at least one property of the magnetic supercluster is a particle size of each magnetic nanoparticle. In some embodiments, the at least one property of the supercluster is a particle size of each magnetic nanoparticle. [0499] In some embodiments, the magnetic supercluster particle has a saturation magnetization (Ms) value of 48 emu/g to 72 emu/g at a magnetic field of 4 Tesla (T). In some embodiments, the magnetic supercluster particle has a saturation magnetization (Ms) value of 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, 60 emu/g, 61 emu/g, 62 emu/g, 63 emu/g, 64 emu/g, 65 emu/g, 66 emu/g, 67 emu/g, 68 emu/g, 69 emu/g, 70 emu/g, 71 emu/g, or 72 emu/g at a magnetic field of 4 Tesla (T), or any range thereof. [0500] In some embodiments, the supercluster has a saturation magnetization (Ms) value of 48 emu/g to 72 emu/g at a magnetic field of 4 Tesla (T). In some embodiments, the supercluster has a saturation magnetization (Ms) value of 48 emu/g, 49 emu/g, 50 emu/g, 51 emu/g, 52 emu/g, 53 emu/g, 54 emu/g, 55 emu/g, 56 emu/g, 57 emu/g, 58 emu/g, 59 emu/g, 60 emu/g, 61 emu/g, 62 emu/g, 63 emu/g, 64 emu/g, 65 emu/g, 66 emu/g, 67 emu/g, 68 emu/g, 69 emu/g, 70 emu/g, 71 emu/g, or 72 emu/g at a magnetic field of 4 Tesla (T), or any range thereof. [0501] In some embodiments, the magnetic nanoparticle has magnetic properties. In some embodiments, each magnetic nanoparticle has magnetic properties. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has magnetic properties. In some embodiments, the plurality of magnetic nanoparticles has magnetic properties. [0502] In some embodiments, the magnetic nanoparticle has at least one magnetic property. In some embodiments, each magnetic nanoparticle has at least one magnetic property. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has ^{4913-4975-3383.1} Page 117 of 144 094876-000024WOPT at least one magnetic property. In some embodiments, the plurality of magnetic nanoparticles has at least one magnetic property. [0503] In some embodiments, the magnetic nanoparticle is a superparamagnetic nanoparticle. In some embodiments, each magnetic nanoparticle is a superparamagnetic nanoparticle. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles is a superparamagnetic nanoparticle. In some embodiments, the plurality of magnetic nanoparticles is a plurality of superparamagnetic nanoparticles. [0504] In some embodiments, the magnetic nanoparticle has superparamagnetic properties. In some embodiments, each magnetic nanoparticle has superparamagnetic properties. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has superparamagnetic properties. In some embodiments, the plurality of magnetic nanoparticles has superparamagnetic properties. [0505] In some embodiments, the magnetic nanoparticle has at least one superparamagnetic property. In some embodiments, each magnetic nanoparticle has at least one superparamagnetic property. In some embodiments, each magnetic nanoparticle of the plurality of magnetic nanoparticles has at least one superparamagnetic property. In some embodiments, the plurality of magnetic nanoparticles has at least one superparamagnetic property. [0506] In some embodiments, at least one magnetic property of the magnetic nanoparticle is controlled by a particle size of the magnetic nanoparticle, a shape of the magnetic nanoparticle, or combination thereof. In some embodiments, at least one magnetic property of the magnetic nanoparticle is controlled by a particle size of the magnetic nanoparticle. In some embodiments, at least one magnetic property of the magnetic nanoparticle is controlled by a shape of the magnetic nanoparticle. [0507] In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by a particle size of the magnetic nanoparticle, a shape of the magnetic nanoparticle, or combination thereof. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by a particle size of the magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by a shape of the magnetic nanoparticle. [0508] In some embodiments, at least one superparamagnetic property of the magnetic nanoparticle is controlled by a particle size of the magnetic nanoparticle, a shape of the magnetic nanoparticle, or combination thereof. In some embodiments, at least one superparamagnetic ^{4913-4975-3383.1} Page 118 of 144 094876-000024WOPT property of the magnetic nanoparticle is controlled by a particle size of the magnetic nanoparticle. In some embodiments, at least one superparamagnetic property of the magnetic nanoparticle is controlled by a shape of the magnetic nanoparticle. [0509] In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by a particle size of the magnetic nanoparticle, a shape of the magnetic nanoparticle, or combination thereof. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by a particle size of the magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by a shape of the magnetic nanoparticle. [0510] In some embodiments, the at least one property of the magnetic nanoparticle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. In some embodiments, the at least one property of the magnetic nanoparticle is controlled by an amount of FeO in the core of the magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of the magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one property of the magnetic nanoparticle is controlled by an amount of FeO in the core of the magnetic nanoparticle. In some embodiments, the at least one property of the magnetic nanoparticle is controlled by an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. [0511] In some embodiments, the at least one property of each magnetic nanoparticle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one property of each magnetic nanoparticle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one property of each magnetic nanoparticle is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one property of each magnetic nanoparticle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0512] In some embodiments, the properties of the magnetic nanoparticle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. In some embodiments, the properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of the magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of the magnetic nanoparticle, or a combination thereof. In some embodiments, the properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of the magnetic nanoparticle. In some ^{4913-4975-3383.1} Page 119 of 144 094876-000024WOPT embodiments, the properties of the magnetic nanoparticle are controlled by an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. [0513] In some embodiments, the properties of each magnetic nanoparticle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the properties of each magnetic nanoparticle are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the properties of each magnetic nanoparticle are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the properties of each magnetic nanoparticle are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0514] In some embodiments, the at least one magnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. In some embodiments, the at least one magnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core of the magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of the magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one magnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core of the magnetic nanoparticle. In some embodiments, the at least one magnetic property of the magnetic nanoparticle is controlled by an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. [0515] In some embodiments, the at least one magnetic property of each magnetic nanoparticle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one magnetic property of each magnetic nanoparticle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one magnetic property of each magnetic nanoparticle is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one magnetic property of each magnetic nanoparticle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0516] In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic nanoparticle are ^{4913-4975-3383.1} Page 120 of 144 094876-000024WOPT controlled by an amount of FeO in the core of the magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of the magnetic nanoparticle, or a combination thereof. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of the magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. [0517] In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the magnetic properties of the magnetic nanoparticle are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0518] In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core of the magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of the magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core of the magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. [0519] In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the at least one superparamagnetic property of the magnetic nanoparticle is controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. ^{4913-4975-3383.1} Page 121 of 144 094876-000024WOPT [0520] In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of the magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of the magnetic nanoparticle, or a combination thereof. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of the magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of Fe₃O₄ in the shell of the magnetic nanoparticle. [0521] In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core and an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of FeO in the core of each magnetic nanoparticle. In some embodiments, the superparamagnetic properties of the magnetic nanoparticle are controlled by an amount of Fe₃O₄ in the shell of each magnetic nanoparticle. [0522] In various embodiments, the present invention provides a composition, comprising at least one magnetic supercluster particle of the present invention. In some embodiments, the at least one magnetic supercluster particle is in dry powder form. In some embodiments, the at least one magnetic supercluster particle is dispersed in a liquid carrier. In various embodiments, the present invention provides a composition, comprising at least one supercluster of the present invention. In some embodiments, the at least one supercluster is in dry powder form. In some embodiments, the at least one supercluster is dispersed in a liquid carrier. [0523] In various embodiments, the present invention provides a method for preparing a magnetic supercluster particle, the method comprising: providing a nanoparticle colloidal solution, wherein the nanoparticle colloidal solution comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; ^{4913-4975-3383.1} Page 122 of 144 094876-000024WOPT providing an aqueous dodecyltrimethylammonium bromide (DTAB) solution; contacting the nanoparticle colloidal solution with the aqueous DTAB solution to provide a mixture; mixing the mixture; heating the mixture; and collecting the magnetic supercluster particle. [0524] In various embodiments, the present invention provides a method for preparing a supercluster, the method comprising: providing a nanoparticle colloidal solution, wherein the nanoparticle colloidal solution comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; providing an aqueous dodecyltrimethylammonium bromide (DTAB) solution; contacting the nanoparticle colloidal solution with the aqueous DTAB solution to provide a mixture; mixing the mixture; heating the mixture; and collecting the supercluster. [0525] In various embodiments, the present invention provides a method for controlling at least one magnetic property of a magnetic supercluster particle, the method comprising: providing a nanoparticle colloidal solution, wherein the nanoparticle colloidal solution comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; providing an aqueous dodecyltrimethylammonium bromide (DTAB) solution; contacting the nanoparticle colloidal solution with the aqueous DTAB solution to provide a mixture; mixing the mixture; heating the mixture; and collecting the magnetic supercluster particle. [0526] In various embodiments, the present invention provides a method for controlling at least one magnetic property of a supercluster, the method comprising: providing a nanoparticle colloidal solution, wherein the nanoparticle colloidal solution comprises a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; providing an aqueous dodecyltrimethylammonium bromide (DTAB) solution; contacting the nanoparticle colloidal solution with the aqueous DTAB solution to provide a mixture; mixing the mixture; heating the mixture; and collecting the supercluster. ^{4913-4975-3383.1} Page 123 of 144 094876-000024WOPT [0527] In some embodiments, the present invention provides use of a supercluster of the present invention as described herein. In some embodiments, the present invention provides use of a magnetic supercluster particle of the present invention as described herein. [0528] Additional embodiments include those listed below. [0529] Embodiment 92. A magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. [0530] Embodiment 93. The magnetic supercluster particle of embodiment 92, wherein each magnetic nanoparticle is independently a nanosphere or a nanocube. [0531] Embodiment 94. The magnetic supercluster particle of embodiment 92, wherein each magnetic nanoparticle independently has a particle size of at least 12 nm. [0532] Embodiment 95. The magnetic supercluster particle of embodiment 92, wherein each magnetic nanoparticle independently has a particle size of at least 20 nm. [0533] Embodiment 96. The magnetic supercluster particle of embodiment 92, wherein the magnetic supercluster particle has a diameter of at least 120 nm. [0534] Embodiment 97. The magnetic supercluster particle of embodiment 92, wherein the magnetic supercluster particle has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T). [0535] Embodiment 98. The magnetic supercluster particle of embodiment 92, wherein the magnetic supercluster particle has a blocking temperature (T_B) of at least 220 Kelvin (K). [0536] Embodiment 99. The magnetic supercluster particle of embodiment 92, wherein the magnetic supercluster particle has at least one superparamagnetic property. [0537] Embodiment 100. The magnetic supercluster particle of embodiment 99, wherein the at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. ^{4913-4975-3383.1} Page 124 of 144 094876-000024WOPT [0538] Embodiment 101. The magnetic supercluster particle of embodiment 99, wherein the at least one superparamagnetic property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. [0539] Embodiment 102. The magnetic supercluster particle of embodiment 99, wherein the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. [0540] Embodiment 103. A composition, comprising at least one magnetic supercluster particle of embodiment 92. [0541] Embodiment 104. An article of manufacture, comprising at least one magnetic supercluster particle of embodiment 92. [0542] Embodiment 105. A magnetic resonance imaging (MRI) contrast agent, comprising at least one magnetic supercluster particle of embodiment 92. [0543] Embodiment 106. A magnetic resonance imaging (MRI) probe, comprising at least one magnetic supercluster particle of embodiment 92. [0544] Embodiment 107. A sensor, comprising at least one magnetic supercluster particle of embodiment 92. [0545] Embodiment 108. An article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one magnetic supercluster particle of embodiment 92. [0546] Embodiment 109. A drug delivery device, comprising at least one magnetic supercluster particle of embodiment 92. [0547] Additional embodiments include those listed below. [0548] Embodiment 110. A magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction. ^{4913-4975-3383.1} Page 125 of 144 094876-000024WOPT [0549] Embodiment 111. The magnetic supercluster particle of embodiment 110, wherein each magnetic nanoparticle is independently a nanosphere or a nanocube. [0550] Embodiment 112. The magnetic supercluster particle of embodiment 110, wherein each magnetic nanoparticle independently has a particle size of at least 12 nm. [0551] Embodiment 113. The magnetic supercluster particle of embodiment 110, wherein each magnetic nanoparticle independently has a particle size of at least 20 nm. [0552] Embodiment 114. The magnetic supercluster particle of embodiment 110, wherein the magnetic supercluster particle has a diameter of at least 120 nm. [0553] Embodiment 115. The magnetic supercluster particle of embodiment 110, wherein the magnetic supercluster particle has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T). [0554] Embodiment 116. The magnetic supercluster particle of embodiment 110, wherein the magnetic supercluster particle has a blocking temperature (T_B) of at least 220 Kelvin (K). [0555] Embodiment 117. The magnetic supercluster particle of embodiment 110, wherein the magnetic supercluster particle has at least one superparamagnetic property. [0556] Embodiment 118. The magnetic supercluster particle of embodiment 117, wherein the at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle. [0557] Embodiment 119. The magnetic supercluster particle of embodiment 117, wherein the at least one superparamagnetic property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof. [0558] Embodiment 120. The magnetic supercluster particle of embodiment 117, wherein the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof. [0559] Embodiment 121. A composition, comprising at least one magnetic supercluster particle of embodiment 110. [0560] Embodiment 122. An article of manufacture, comprising at least one magnetic supercluster particle of embodiment 110. [0561] Embodiment 123. A magnetic resonance imaging (MRI) contrast agent, comprising at least one magnetic supercluster particle of embodiment 110. ^{4913-4975-3383.1} Page 126 of 144 094876-000024WOPT [0562] Embodiment 124. A magnetic resonance imaging (MRI) probe, comprising at least one magnetic supercluster particle of embodiment 110. [0563] Embodiment 125. A sensor, comprising at least one magnetic supercluster particle of embodiment 110. [0564] Embodiment 126. An article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one magnetic supercluster particle of embodiment 110. [0565] Embodiment 127. A drug delivery device, comprising at least one magnetic supercluster particle of embodiment 110. EXAMPLES [0566] The following examples illustrate some embodiments and aspects of the invention. It will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be performed without altering the spirit or scope of the invention, and such modifications and variations are encompassed within the scope of the invention as defined in the claims which follow. The following examples do not in any way limit the invention. [0567] Chapter 1 – Examples [0568] Materials. For the synthesis of iron oxide nanoparticles, iron(III) chloride hexahydrate (97%, Alfa Aesar), sodium oleate (97%, TCI), oleic acid (90%, Sigma-Aldrich), 1- hexadecene (90%, Sigma-Aldrich), 1-octadecene (90%, Sigma-Aldrich), and 1-docosane (90%, Sigma-Aldrich) were used. Common solvents such as deionized water with a resistance of 18 MΩ- cm (Academic Milli-Q Water System, Millipore Corporation), ethanol (200 proof, Decon Labs), cyclohexane (99%, Sigma-Aldrich), and n-hexane (99%, Oakwood) were consistently used. [0569] Example 1. Synthesis of Iron Oleate Precursors. The iron(III) oleate precursors were synthesized as previously reported (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Nanocrystals. Nat. Mater.2004, 3, 891–895). First, a mixture of 10.8 g of FeCl₃·6H₂O, 36.5 g of sodium oleate, 80 mL of ethanol, 60 mL of deionized water, and 140 mL of hexane was refluxed at 70°C for 4 hours. The product was then transferred to a separation funnel, with the top organic layer containing iron oleate precursors and the bottom aqueous solution being removed. The iron oleate in the organic layer was extracted at least 5 times with 200 mL of Milli-Q water each time, ^{4913-4975-3383.1} Page 127 of 144 094876-000024WOPT followed by the evaporation of hexane using a rotary evaporator. The iron oleate product was then dried in an 80°C oven for 48 hours. [0570] Example 2. Synthesis of Spherical Iron Oxide Nanoparticles. Iron oxide nanospheres with tunable sizes were synthesized by the thermal decomposition of iron oleate with oleic acid and 1-octadecene, as reported by previous methods with modifications (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large- Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater.2004, 3, 891–895; Balakrishnan, T.; Lee, M.-J.; Dey, J.; Choi, S.-M. Sub-Nanometer Scale Size-Control of Iron Oxide Nanoparticles with Time of Iron Oleate. CrystEngComm 2019, 21, 4063–4071). Prior to the reaction, the was degassed with N₂ for 2 hours, then minimal N₂ bubbling was maintained throughout the reaction time. The reflux was conducted at 310°C for 30 minutes, with a heating rate of approximately 28 to 32°C. The concentration of iron oleate precursors was used to control the size of the nanoparticles. Using 1.8 g of iron oleate with 0.285 g of oleic acid (OA) in 12.57 g of octadecene solvent was able to produce iron oxide nanoparticles with sizes around 10 nm. By increasing the concentration of iron oleate, adjusting the amount of oleic acid surfactant, and controlling the heating rate, various sizes of iron oxide nanospheres could be produced, ranging from 10 to 28 nm. The amount of iron(III) oleate used for tuning the size of nanoparticles varied from 1.8 to 2.8 g. It is worth noting that the amount of oleic acid could be adjusted from 15 to 20% to form nanoparticles with a rounder shape; however, this could slightly shift the size of the nanoparticles. The round-bottom flask was washed with aqua regia, followed by piranha solution, and dried in a 150°C oven overnight. To wash the nanoparticles, they were precipitated by adding ethanol (EtOH) to the nanoparticle colloidal solution (in hexane), followed by centrifugation to remove the supernatant. The nanoparticles were redispersed in hexane with the addition of 50 to 100 μL of OA to improve colloidal stability and prevent aggregation. The nanoparticles were washed three times prior to storage in a 4°C refrigerator. [0571] Example 3. Synthesis of Cubic Iron Oxide Nanoparticles. The thermal decomposition of 1.8 g of iron(III) oleate in a mixture of solvents (1-octadecene and docosane) with the assistance of sodium oleate and oleic acid surfactants was used to produce iron oxide nanocubes of different sizes. This method was adapted from previous work with modifications (Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core– ^{4913-4975-3383.1} Page 128 of 144 094876-000024WOPT Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater. 2023, 35, 6201–6219; Lak, A.; Cassani, M.; Mai, B. T.; Winckelmans, N.; Cabrera, D.; Sadrollahi, E.; Marras, S.; Remmer, H.; Fiorito, S.; Cremades-Jimeno, L.; Litterst, F. J.; Ludwig, F.; Manna, L.; Teran, F. J.; Bals, S.; Pellegrino, T. Fe²⁺ Deficiencies, FeO Subdomains, and Structural Defects Favor Magnetic Hyperthermia Performance of Iron Oxide Nanocubes into Intracellular Environment. Nano Lett.2018, 18, 6856– 6866). The solvent compositions and reaction temperature were used to control the size of the nanocubes, with details specified in Table 9. Prior to refluxing, the mixture was maintained at 100°C for 30 minutes, followed by heating to 200°C and holding for another 30 minutes. All reactions were subjected to reflux for 30 minutes. After the synthesis, the glassware and nanoparticles were treated similarly to the spherical nanoparticles. Finally, the nanoparticles were stored in a 4°C refrigerator. [0572] Table 9. Synthetic Conditions for Iron Oxide Nanocubes with Different Sizes. Size Iron Oleate Sodium Oleic 1-octadecene Docosane Temp ° C C C C [0573] Example 4. Forming Superclusters. Superclusters were prepared using a method reported in previous publications with modifications (Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc.2018, 140, 15038–15047; Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self-Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C ^{4913-4975-3383.1} Page 129 of 144 094876-000024WOPT 2021, 125, 5880–5889). The nanoparticles were separated from the stock solution by centrifugation at 6000 rpm for 5 minutes. Prior to centrifugation, ethanol was added to the stock colloidal solution to facilitate easier separation by centrifugation. The volume ratio of stock colloidal solutions to ethanol could be 1:1 for size 13 nm, 3:1 for size 16 nm, and 7:1 for size 21 nm. The supernatant was completely removed after centrifugation, and the pellet was redispersed in chloroform. To ensure the nanoparticles formed a colloidal solution in chloroform without aggregation, the colloidal was thoroughly sonicated in an ultrasonication bath with the addition of 10 μL of oleic acid (OA) surfactant. The nanoparticle colloidal solution was then added to the DTAB solution, followed by vortexing for exactly 90 seconds. The organic solvent was evaporated by heating at 55–60 °C for 4 hours under magnetic stirring. The supercluster particles were collected by centrifugation (3000 rpm, 5 minutes) and washed with ethanol at least 4 times. The conditions to fabricate superclusters with different sizes of nanoparticles were specified in Table 10. It was observed that the concentration of the nanoparticle colloidal solution is the most important parameter in determining the formation of superclusters. [0574] Table 10. Formation Conditions of Superclusters with Nanoparticles of Different Sizes and Shapes. Nanoparticles Nanoparticles DTAB in H2O Size of Vortex (s) ^{4913-4975-3383.1} Page 130 of 144 094876-000024WOPT [0575] Materials Characterization. The nanoparticles were characterized by a Transmission Electron Microscope (TEM) JEOL 2010F at an acceleration voltage of 200 kV. A X- ray Diffractometer (Smart Lab, Rigaku) with Cu Kα irradiation at 40 mA and 44 kV was used for crystallographic analysis. The nanoparticles were dropped onto cleaned glass substrates for characterization, with a scanning rate of 2°/min. The superclusters were imaged using a Scanning Electron Microscope (SEM) JSM-6330F at an acceleration voltage of 15 kV. A Superconducting Quantum Interference Device (SQUID) MPMS 3 by Quantum Design was used to characterize the magnetic properties. Magnetization dependence on the applied field measurements, M(H), were conducted at 300 K in the range of ± 40 kOe. Magnetization dependence on temperature measurements, M(T), were conducted following the typical zero-field-cooling/field-cooling (ZFC/FC) protocol at a field of 100 Oe. [0576] Chapter 2 – Examples [0577] Materials. For the synthesis of iron oxide nanoparticles (IONPs), the following chemicals were used: iron(III) chloride hexahydrate (97%; Alfa Aesar), sodium oleate (97%; TCI), oleic acid (90%; Sigma-Aldrich), 1-hexadecene (90%; Sigma-Aldrich), 1-octadecene (90%; Sigma-Aldrich), and 1-docosane (90%; Sigma-Aldrich). Common solvents employed included deionized water with a resistance of 18 MΩ-cm (Academic Milli-Q Water System; Millipore Corporation), ethanol (200 proof; Decon Labs), cyclohexane (99%; Sigma-Aldrich), and n-hexane (99%; Oakwood). [0578] Example 5. Synthesis of Iron Oleate Precursors. Iron(III) oleate precursors were synthesized as previously reported (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.- Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses Nanocrystals. Nat. Mater.2004, 3, 891–895). First, a mixture of 10.8 g of FeCl₃·6H₂O, 36.5 g of sodium oleate, 80 mL of ethanol, 60 mL of deionized water, and 140 mL of hexane was refluxed at 70 °C for 4 hours. The mixture was then transferred to a separatory funnel, where the top organic layer containing iron oleate precursors was separated, and the bottom aqueous solution was removed. The iron oleate in the organic layer was extracted at least five times with 200 mL of Milli-Q water each time. Subsequently, hexane was evaporated using a rotary evaporator. The iron oleate product was then dried in an oven at 80 °C for 48 hours. [0579] Example 6. Synthesis of Spherical Iron Oxide Nanoparticles. Iron oxide nanospheres (IONSs) with tunable sizes were synthesized by the thermal decomposition of iron ^{4913-4975-3383.1} Page 131 of 144 094876-000024WOPT oleate in the presence of oleic acid and 1-octadecene, as previously described with modifications (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater. 2004, 3, 891–895; Balakrishnan, T.; Lee, M.-J.; Dey, J.; Choi, Sub-Nanometer Scale Size-Control of Iron Oxide Nanoparticles with Drying Time of Iron Oleate. CrystEngComm 2019, 21, 4063–4071; Tancredi, P.; Rivas Rojas, P. C.; Moscoso-Londoño, O.; Wolff, U.; Neu, V.; Damm, C.; Rellinghaus, B.; Knobel, M.; M. Socolovsky, L. Synthesis Process, Size and Composition Effects of Spherical Fe₃O₄ and FeO@Fe₃O₄ Core/Shell Nanoparticles. New J. Chem.2017, 41, 15033–15041). Prior to the reaction, the solution was degassed with N₂ for 2 hours, and minimal N₂ bubbling was maintained throughout the reaction. The mixture was refluxed at 310 °C for 30 minutes, with a heating rate of approximately 30 °C per minute. The concentration of iron oleate precursors was varied to control the size of the NPs. A mixture of 1.8 g of iron oleate and 0.285 g of oleic acid (OA) in 12.57 g of octadecene solvent produced IONPs approximately 10 nm in size. By increasing the concentration of iron oleate, adjusting the amount of oleic acid surfactant, and controlling the heating rate, various sizes of iron oxide nanospheres could be produced, ranging from 10 to 28 nm. The amount of iron(III) oleate used (1.8 to 2.8 g) was systematically varied to tune the size of NPs. Notably, adjusting the oleic acid concentration from 15 to 20% could produce rounder NPs, albeit with a slight shift to larger sizes. The round-bottom flask was cleaned with aqua regia, followed by piranha solution, and dried overnight in a 150 °C oven. To wash the NPs, ethanol (EtOH) was added to the colloidal solution (in hexane), followed by centrifugation to remove the supernatant. The NPs were redispersed in hexane with the addition of 50 to 100 μL of OA to enhance colloidal stability and prevent aggregation. The NPs were washed three times before being stored in a 4 °C refrigerator. [0580] Example 7. Synthesis of Cubic Iron Oxide Nanoparticles. Iron oxide nanocubes (IONCs) of varying sizes were synthesized through the thermal decomposition of 1.8 g of iron(III) oleate in a solvent mixture of 1-octadecene and docosane, facilitated by sodium oleate and oleic acid surfactants. This method was adapted from previous work, with modifications (Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core–Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater. 2023, 35, 6201–6219; Lak, A.; Cassani, M.; Mai, B. T.; ^{4913-4975-3383.1} Page 132 of 144 094876-000024WOPT Winckelmans, N.; Cabrera, D.; Sadrollahi, E.; Marras, S.; Remmer, H.; Fiorito, S.; Cremades- Jimeno, L.; Litterst, F. J.; Ludwig, F.; Manna, L.; Teran, F. J.; Bals, S.; Pellegrino, T. Fe²⁺ Deficiencies, FeO Subdomains, and Structural Defects Favor Magnetic Hyperthermia Performance of Iron Oxide Nanocubes into Intracellular Environment. Nano Lett.2018, 18, 6856– 6866). The solvent compositions and reaction temperature, detailed in Table 11, were used to control the size of the nanocubes. Before refluxing, the mixture was held at 100 °C for 30 minutes, then heated to 200 °C and maintained for an additional 30 minutes. All reactions were subjected to 30 minutes of reflux. After synthesis, the glassware and NPs underwent a cleaning process similar to that used for spherical NPs. Finally, the NPs were stored in a 4°C refrigerator. [0581] Table 11. Synthetic Conditions for Iron Oxide Nanocubes of Varying Sizes. Particle Iron Oleate Sodium Oleic 1-octadecene Docosane Temperature Si ( ) Ol t ( ) A id ( ) ( L) ( ) (°C) [0582] Example 8. Formation of Superclusters. Superclusters were prepared using a method reported in previous publications, with modifications (Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc.2018, 140, 15038–15047; Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self-Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). The NPs were separated from the stock solution by centrifugation ^{4913-4975-3383.1} Page 133 of 144 094876-000024WOPT at 6000 rpm for 5 minutes. Ethanol was added to the stock colloidal solution prior to centrifugation to facilitate separation. The volume ratio of stock colloidal solutions to ethanol was set at 1:1 for a size of 13 nm, 3:1 for 16 nm, and 7:1 for 21 nm. The supernatant was removed after centrifugation, and the pellet was redispersed in chloroform. To ensure that the NPs formed a stable colloidal solution in chloroform without aggregating, the solution was sonicated thoroughly in an ultrasonication bath with the addition of 10 μL of OA surfactant. The NP colloidal solution was then added to the DTAB solution, followed by vortexing for exactly 90 seconds. The organic solvent was evaporated by heating at 55–60 °C for 4 hours under magnetic stirring. The supercluster particles were collected by centrifugation (3000 rpm, 5 minutes) and washed with ethanol at least four times. The conditions for fabricating superclusters with varying sizes of nanoparticles are specified in Table 12. We observed that the concentration of the NP colloidal solution was the most important parameter in determining the formation of superclusters. [0583] Table 12. Formation Conditions of Superclusters with Nanoparticles of Varying Sizes and Shapes. Size of Nanoparticle DTAB in H₂O Size of Vortex Time [0584] Materials Characterization. The iron oxide nanospheres and nanocubes were characterized using transmission electron microscopy. The lower resolution/lower magnification images were collected using a TEM (JEOL 2010F) at an acceleration voltage of 200 kV. The atomic ^{4913-4975-3383.1} Page 134 of 144 094876-000024WOPT resolution images were collected using a Titan/Themis at an acceleration voltage of 300 kV. In both cases, the particles were deposited on holey carbon Cu grids 300 mesh. The TEM image analysis was carried out using DigitalMicrograph and Velox software. A powder X-ray diffractometer (PXRD) (Smart Lab, Rigaku), operating with Cu Kα irradiation at 40 mA and 44 kV with a scanning rate of 2°/min, was used for crystallographic analysis. To prepare sample for PXRD analysis, the powder of NPs was dropped onto cleaned glass substrates. The superclusters were imaged using a scanning electron microscope (SEM, JSM-6330F) at an acceleration voltage of 15 kV. X-ray photoelectron spectroscopy (XPS) analyses were performed using a PHI 5700 X- ray photoelectron spectrometer with a monochromatic Al Kα X-ray source to characterize the iron oxide nanoparticles drop-casted on a cleaned silicon wafer. The C 1s peak at a binding energy of 284.8 eV was used for calibration. The Raman scattering spectra of samples were measured with a Horiba JY T64000 triple spectrometer coupled with an Olympus optical microscope. The microscope focused a 488 nm laser beam onto the sample using x100 objectives. Magnetic properties were characterized by a superconducting quantum interference device (SQUID, MPMS3, Quantum Design). Magnetic field-dependent magnetization measurements (M(H)) were conducted at 300 K in the range of ±40 kOe. Temperature-dependent magnetization measurements (M(T)) were conducted over a broad temperature range (2 to 400 K) following a standard zero- field-cooled/field-cooled (ZFC/FC) measurement protocol at a field strength of 100 Oe. [0585] Chapter 3 – Examples [0586] Materials. For the synthesis of iron oxide nanoparticles (IONPs), the following chemicals were used: iron(III) chloride hexahydrate (97%; Alfa Aesar), sodium oleate (97%; TCI), oleic acid (90%; Sigma-Aldrich), 1-hexadecene (90%; Sigma-Aldrich), 1-octadecene (90%; Sigma-Aldrich), and 1-docosane (90%; Sigma-Aldrich). Common solvents employed included deionized water with a resistance of 18 MΩ-cm (Academic Milli-Q Water System; Millipore Corporation), ethanol (200 proof; Decon Labs), cyclohexane (99%; Sigma-Aldrich), and n-hexane (99%; Oakwood). [0587] Example 9. Synthesis of Iron Oleate Precursors. Iron(III) oleate precursors were synthesized as previously reported (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.- Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater.2004, 3, 891–895). First, a mixture of 10.8 g of FeCl₃·6H₂O, 36.5 g of sodium oleate, 80 mL of ethanol, 60 mL of deionized water, and 140 mL of hexane was refluxed ^{4913-4975-3383.1} Page 135 of 144 094876-000024WOPT at 70 °C for 4 hours. The mixture was then transferred to a separatory funnel, where the top organic layer containing iron oleate precursors was separated, and the bottom aqueous solution was removed. The iron oleate in the organic layer was extracted at least five times with 200 mL of Milli-Q water each time. Subsequently, hexane was evaporated using a rotary evaporator. The iron oleate product was then dried in an oven at 80 °C for 48 hours. [0588] Example 10. Synthesis of Spherical Iron Oxide Nanoparticles. Iron oxide nanospheres (IONSs) with tunable sizes were synthesized by the thermal decomposition of iron oleate in the presence of oleic acid and 1-octadecene, as previously described with modifications (Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Hwang, N.-M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater. 2004, 3, 891–895; Tancredi, P.; Rivas Rojas, P. C.; Moscoso-Londoño, O.; Wolff, U.; Neu, V.; Damm, C.; Rellinghaus, B.; Knobel, M.; M. Socolovsky, L. Synthesis Process, Size and Composition Effects of Spherical Fe₃O₄ and FeO@Fe₃O₄ Core/Shell Nanoparticles. New J. Chem. 2017, 41, 15033– 15041; Balakrishnan, T.; Lee, M.-J.; Dey, J.; Choi, S.-M. Sub-Nanometer Scale Size-Control of Iron Oxide Nanoparticles with Drying Time of Iron Oleate. CrystEngComm 2019, 21, 4063–4071). Prior to the reaction, the solution was degassed with N₂ for 2 hours, and minimal N₂ bubbling was maintained throughout the reaction. The mixture was refluxed at 310 °C for 30 minutes, with a heating rate of approximately 30 °C per minute. The concentration of iron oleate precursors was varied to control the size of the NPs. A mixture of 1.8 g of iron oleate and 0.285 g of oleic acid (OA) in 12.57 g of octadecene solvent produced IONPs approximately 10 nm in size. By increasing the concentration of iron oleate, adjusting the amount of oleic acid surfactant, and controlling the heating rate, various sizes of iron oxide nanospheres could be produced, ranging from 10 to 28 nm. The amount of iron(III) oleate used (1.8 to 2.8 g) was systematically varied to tune the size of NPs. Notably, adjusting the oleic acid concentration from 15 to 20% could produce rounder NPs, albeit with a slight shift to larger sizes. After synthesis, the reaction was allowed to cool naturally to approximately 60 °C before starting the washing process. The cooling process from the reaction temperature to this range took about 1 to 1 hour and 15 minutes. The round-bottom flask was cleaned with aqua regia, followed by piranha solution, and dried overnight in a 150 °C oven. To wash the NPs, ethanol (EtOH) was added to the colloidal solution (in hexane), followed by centrifugation to remove the supernatant. The NPs were redispersed in hexane with the addition ^{4913-4975-3383.1} Page 136 of 144 094876-000024WOPT of 50 to 100 μL of OA to enhance colloidal stability and prevent aggregation. The NPs were washed three times before being stored in a 4 °C refrigerator. [0589] Example 11. Synthesis of Cubic Iron Oxide Nanoparticles. Iron oxide nanocubes (IONCs) of varying sizes were synthesized through the thermal decomposition of 1.8 g of iron(III) oleate in a solvent mixture of 1-octadecene and docosane, facilitated by sodium oleate and oleic acid surfactants. This method was adapted from previous work, with modifications (Sojková, T.; Rizzo, G. M. R.; Di Girolamo, A.; Avugadda, S. K.; Soni, N.; Milbrandt, N. B.; Tsai, Y. H.; Kuběna, I.; Sojka, M.; Silvestri, N.; Samia, A. C.; Gröger, R.; Pellegrino, T. From Core–Shell FeO/Fe₃O₄ to Magnetite Nanocubes: Enhancing Magnetic Hyperthermia and Imaging Performance by Thermal Annealing. Chem. Mater. 2023, 35, 6201–6219; Lak, A.; Cassani, M.; Mai, B. T.; Winckelmans, N.; Cabrera, D.; Sadrollahi, E.; Marras, S.; Remmer, H.; Fiorito, S.; Cremades- Jimeno, L.; Litterst, F. J.; Ludwig, F.; Manna, L.; Teran, F. J.; Bals, S.; Pellegrino, T. Fe²⁺ Deficiencies, FeO Subdomains, and Structural Defects Favor Magnetic Hyperthermia Performance of Iron Oxide Nanocubes into Intracellular Environment. Nano Lett.2018, 18, 6856– 6866). The solvent compositions and reaction temperature, detailed in Table 13, were used to control the size of the nanocubes. Before refluxing, the mixture was held at 100 °C for 30 minutes, then heated to 200 °C and maintained for an additional 30 minutes. All reactions were subjected to 30 minutes of reflux. Similarly, natural cooling protocol for post-synthesis of spherical nanoparticles was applied. After synthesis, the glassware and NPs underwent a cleaning process similar to that used for spherical NPs. Finally, the NPs were stored in a 4°C refrigerator. [0590] Table 13. Synthetic Conditions for Iron Oxide Nanocubes of Varying Sizes. Particle Iron Oleate Sodium Oleic Acid 1-octadecene Docosane Temperature [0591] Example 12. Formation of Superclusters. Superclusters were prepared using a method reported in previous publications, with modifications (Yang, Y.; Wang, B.; Shen, X.; Yao, ^{4913-4975-3383.1} Page 137 of 144 094876-000024WOPT L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc.2018, 140, 15038–15047; Xu, W.; Ji, M.; Chen, Y.; Zheng, H.; Wang, L.; Peng, D.-L. Nickel Colloidal Superparticles: Microemulsion-Based Self-Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism. J. Phys. Chem. C 2021, 125, 5880–5889). The NPs were separated from the stock solution by centrifugation at 6000 rpm for 5 minutes. Ethanol was added to the stock colloidal solution prior to centrifugation to facilitate separation. The volume ratio of stock colloidal solutions to ethanol was set at 1:1 for a size of 13 nm, 3:1 for 16 nm, and 7:1 for 21 nm. The supernatant was removed after centrifugation, and the pellet was redispersed in chloroform. To ensure that the NPs formed a stable colloidal solution in chloroform without aggregating, the solution was sonicated thoroughly in an ultrasonication bath with the addition of 10 μL of OA surfactant. The NP colloidal solution was then added to the DTAB solution, followed by vortexing for exactly 90 seconds. The organic solvent was evaporated by heating at 55–60 °C for 4 hours under magnetic stirring. The supercluster particles were collected by centrifugation (3000 rpm, 5 minutes) and washed with ethanol at least four times. The conditions for fabricating superclusters with varying sizes of nanoparticles are specified in Table 14. We observed that the concentration of the NP colloidal solution was the most important parameter in determining the formation of superclusters. [0592] Table 14. Formation Conditions of Superclusters with Nanoparticles of Varying Sizes and Shapes. Size of Nanoparticle DTAB in H2O Size of Vortex Time ^{4913-4975-3383.1} Page 138 of 144 094876-000024WOPT 15.6 ± 1.3 10 mg/mL, 2.0 mL 20 mg/mL, 2.0 mL 241 ± 57 90 s (nanospheres) . ere characterized using transmission electron microscopy. The lower resolution/lower magnification images were collected using a TEM (JEOL 2010F) at an acceleration voltage of 200 kV. The atomic resolution images were collected using a Titan/Themis at an acceleration voltage of 300 kV. In both cases, the particles were deposited on holey carbon Cu grids 300 mesh. The TEM image analysis was carried out using DigitalMicrograph and Velox software. A powder X-ray diffractometer (PXRD) (Smart Lab, Rigaku), operating with Cu Kα irradiation at 40 mA and 44 kV with a scanning rate of 2°/min, was used for crystallographic analysis. To prepare sample for PXRD analysis, the powder of NPs was dropped onto cleaned glass substrates. The superclusters were imaged using a scanning electron microscope (SEM, JSM-6330F) at an acceleration voltage of 15 kV. X-ray photoelectron spectroscopy (XPS) analyses were performed using a PHI 5700 X- ray photoelectron spectrometer with a monochromatic Al Kα X-ray source to characterize the iron oxide nanoparticles drop-casted on a cleaned silicon wafer. The C 1s peak at a binding energy of 284.8 eV was used for calibration. The Raman scattering spectra of samples were measured with a Horiba JY T64000 triple spectrometer coupled with an Olympus optical microscope. The microscope focused a 488 nm laser beam onto the sample using x100 objectives. Magnetic properties were characterized by a superconducting quantum interference device (SQUID, MPMS3, Quantum Design). Magnetic field-dependent magnetization measurements (M(H)) were conducted at 300 K in the range of ±40 kOe. Temperature-dependent magnetization measurements (M(T)) were conducted over a broad temperature range (2 to 400 K) following a standard zero- field-cooled/field-cooled (ZFC/FC) measurement protocol at a field strength of 100 Oe. [0594] The various methods and techniques described above provide a number of ways to carry out the application. Of course, it is to be understood that not necessarily all objectives or advantages described can be achieved in accordance with any particular embodiment described herein. Thus, for example, those skilled in the art will recognize that the methods can be performed in a manner that achieves or optimizes one advantage or group of advantages as taught herein ^{4913-4975-3383.1} Page 139 of 144 094876-000024WOPT without necessarily achieving other objectives or advantages as taught or suggested herein. A variety of alternatives are mentioned herein. It is to be understood that some preferred embodiments specifically include one, another, or several features, while others specifically exclude one, another, or several features, while still others mitigate a particular feature by inclusion of one, another, or several advantageous features. [0595] Furthermore, the skilled artisan will recognize the applicability of various features from different embodiments. Similarly, the various elements, features and steps discussed above, as well as other known equivalents for each such element, feature, or step, can be employed in various combinations by one of ordinary skill in this art to perform methods in accordance with the principles described herein. Among the various elements, features, and steps some will be specifically included and others specifically excluded in diverse embodiments. [0596] Although the application has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the embodiments of the application extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and modifications and equivalents thereof. [0597] Preferred embodiments of this application are described herein, including the best mode known to the inventors for carrying out the application. Variations on those preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. It is contemplated that skilled artisans can employ such variations as appropriate, and the application can be practiced otherwise than specifically described herein. Accordingly, many embodiments of this application include all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the application unless otherwise indicated herein or otherwise clearly contradicted by context. [0598] All patents, patent applications, publications of patent applications, and other material, such as articles, books, specifications, publications, documents, things, and/or the like, referenced herein are hereby incorporated herein by this reference in their entirety for all purposes, excepting any prosecution file history associated with same, any of same that is inconsistent with or in conflict with the present document, or any of same that may have a limiting affect as to the broadest scope of the claims now or later associated with the present document. By way of example, should there be any inconsistency or conflict between the description, definition, and/or ^{4913-4975-3383.1} Page 140 of 144 094876-000024WOPT the use of a term associated with any of the incorporated material and that associated with the present document, the description, definition, and/or the use of the term in the present document shall prevail. [0599] It is to be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of the application. Other modifications that can be employed can be within the scope of the application. Thus, by way of example, but not of limitation, alternative configurations of the embodiments of the application can be utilized in accordance with the teachings herein. Accordingly, embodiments of the present application are not limited to that precisely as shown and described. [0600] Various embodiments of the invention are described above in the Detailed Description. While these descriptions directly describe the above embodiments, it is understood that those skilled in the art may conceive modifications and/or variations to the specific embodiments shown and described herein. Any such modifications or variations that fall within the purview of this description are intended to be included therein as well. Unless specifically noted, it is the intention of the inventors that the words and phrases in the specification and claims be given the ordinary and accustomed meanings to those of ordinary skill in the applicable art(s). [0601] The foregoing description of various embodiments of the invention known to the applicant at this time of filing the application has been presented and is intended for the purposes of illustration and description. The present description is not intended to be exhaustive nor limit the invention to the precise form disclosed and many modifications and variations are possible in the light of the above teachings. The embodiments described serve to explain the principles of the invention and its practical application and to enable others skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, it is intended that the invention is not limited to the particular embodiments disclosed for carrying out the invention. [0602] While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention. ^{4913-4975-3383.1} Page 141 of 144 094876-000024WOPT

Claims

CLAIMS What is claimed is: 1. A magnetic supercluster particle, comprising: a plurality of magnetic nanoparticles; wherein each magnetic nanoparticle comprises a core and a shell surrounding the core; wherein the core is FeO and the shell is Fe₃O₄; wherein each magnetic nanoparticle is at least partially coated with an oleic acid capping agent; and wherein each magnetic nanoparticle in the magnetic supercluster particle is non-covalently associated with at least one other magnetic nanoparticle in the magnetic supercluster particle through an intermolecular interaction.

2. The magnetic supercluster particle of claim 1, wherein each magnetic nanoparticle is independently a nanosphere or a nanocube.

3. The magnetic supercluster particle of claim 1, wherein each magnetic nanoparticle independently has a particle size of at least 12 nm.

4. The magnetic supercluster particle of claim 1, wherein each magnetic nanoparticle independently has a particle size of at least 20 nm.

5. The magnetic supercluster particle of claim 1, wherein the magnetic supercluster particle has a diameter of at least 120 nm.

6. The magnetic supercluster particle of claim 1, wherein the magnetic supercluster particle has a saturation magnetization (Ms) value of at least 48 emu/g at a magnetic field of 4 Tesla (T).

7. The magnetic supercluster particle of claim 1, wherein the magnetic supercluster particle has a blocking temperature (T_B) of at least 220 Kelvin (K).

8. The magnetic supercluster particle of claim 1, wherein the magnetic supercluster particle has at least one superparamagnetic property. ^{4913-4975-3383.1} Page 142 of 144 094876-000024WOPT

9. The magnetic supercluster particle of claim 8, wherein the at least one superparamagnetic property of the magnetic supercluster particle is controlled by at least one magnetic property of each magnetic nanoparticle in the magnetic supercluster particle.

10. The magnetic supercluster particle of claim 8, wherein the at least one superparamagnetic property of the magnetic supercluster particle is saturation magnetization (Ms), or blocking temperature (T_B), or combination thereof.

11. The magnetic supercluster particle of claim 8, wherein the at least one superparamagnetic property of the magnetic supercluster particle is controlled by an amount of FeO in the core of each magnetic nanoparticle, or an amount of Fe₃O₄ in the shell of each magnetic nanoparticle, or a combination thereof.

12. A composition, comprising at least one magnetic supercluster particle of claim 1.

13. An article of manufacture, comprising at least one magnetic supercluster particle of claim 1.

14. A magnetic resonance imaging (MRI) contrast agent, comprising at least one magnetic supercluster particle of claim 1.

15. A magnetic resonance imaging (MRI) probe, comprising at least one magnetic supercluster particle of claim 1.

16. A sensor, comprising at least one magnetic supercluster particle of claim 1.

17. An article of manufacture suitable for magnetic hyperthermia, wherein the article of manufacture comprises at least one magnetic supercluster particle of claim 1.

18. A drug delivery device, comprising at least one magnetic supercluster particle of claim 1. ^{4913-4975-3383.1} Page 143 of 144 094876-000024WOPT