WO2019218027A1 - Particules de type noyau-enveloppe - Google Patents

Particules de type noyau-enveloppe Download PDF

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Publication number
WO2019218027A1
WO2019218027A1 PCT/AU2019/050475 AU2019050475W WO2019218027A1 WO 2019218027 A1 WO2019218027 A1 WO 2019218027A1 AU 2019050475 W AU2019050475 W AU 2019050475W WO 2019218027 A1 WO2019218027 A1 WO 2019218027A1
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Prior art keywords
group
core
poly
shell
silica
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PCT/AU2019/050475
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English (en)
Inventor
Shane MEANEY
Richard Tabor
Bart FOLLINK
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Monash University
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Priority claimed from AU2018901755A external-priority patent/AU2018901755A0/en
Application filed by Monash University filed Critical Monash University
Publication of WO2019218027A1 publication Critical patent/WO2019218027A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C08J3/128—Polymer particles coated by inorganic and non-macromolecular organic compounds
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/26—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests in coated particulate form
    • A01N25/28—Microcapsules or nanocapsules
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/26—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests in coated particulate form
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/001—Preparation for luminescence or biological staining
    • A61K49/0063—Preparation for luminescence or biological staining characterised by a special physical or galenical form, e.g. emulsions, microspheres
    • A61K49/0065—Preparation for luminescence or biological staining characterised by a special physical or galenical form, e.g. emulsions, microspheres the luminescent/fluorescent agent having itself a special physical form, e.g. gold nanoparticle
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
    • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
    • A61K9/167—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction with an outer layer or coating comprising drug; with chemically bound drugs or non-active substances on their surface
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/51—Nanocapsules; Nanoparticles
    • A61K9/5107—Excipients; Inactive ingredients
    • A61K9/5115—Inorganic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/08—Silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B09C1/08—Reclamation of contaminated soil chemically
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/146—After-treatment of sols
    • C01B33/149—Coating
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B17/00—Other phosphatic fertilisers, e.g. soft rock phosphates, bone meal
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/24—Homopolymers or copolymers of amides or imides
    • C08L33/26—Homopolymers or copolymers of acrylamide or methacrylamide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L81/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
    • B01J2523/10—Constitutive chemical elements of heterogeneous catalysts of Group I (IA or IB) of the Periodic Table
    • B01J2523/19—Gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
    • C08J2325/18—Homopolymers or copolymers of aromatic monomers containing elements other than carbon and hydrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/24—Homopolymers or copolymers of amides or imides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/24—Homopolymers or copolymers of amides or imides
    • C08J2333/26—Homopolymers or copolymers of acrylamide or methacrylamide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2339/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2347/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds; Derivatives of such polymers

Definitions

  • the present invention relates generally to core-shell particles, and in particular to a polyelectrolyte polymer- silica core-shell particle and a method for preparing the same.
  • Polyelectrolyte polymer- silica composites are an important class of materials with applications in sensors, self-healing, and coatings.
  • the presence of distinct organic and inorganic phases provides complementary physiochemical properties.
  • Silica typically provides a solid, inert substrate with improved resistance to thermal, chemical, and mechanical damage when compared to bare polymer phases.
  • the polyelectrolyte polymer conversely offers a wealth of possible chemical environments and opens manifold avenues for tailoring the function of the material.
  • polyelectrolyte polymer- silica composites offer potentially new application avenues in fields such as agriculture, fluid purification, and drug-delivery.
  • Composites are however often more than the sum of their components, with enhanced properties observed from the synergism between these materials.
  • encapsulation of a polyelectrolyte core within a silica-based shell results in a particulate material having the desired compartmentalised functionality.
  • the synthesis of such particle architecture has been successful, the resulting particles still suffer from limited real-world applicability due to their inherent mechanical instability, high solubility of the core in polar solvents, and for being chemically inert.
  • the present invention provides a core-shell particle having:
  • the core being a cross-linked polyelectrolyte core
  • the mechanical stability of the core shell particle is advantageously superior to that of conventional polyelectrolyte-silica core shell particles.
  • the cross-linked polyelectrolyte core is insoluble in polar solvents and can be stored in dry form, greatly enhancing the practical handling and shelf-life of the core-shell particles.
  • the cross-linked polyelectrolyte core also ensures that the mechanical stability of the particle is preserved also for larger core-shell particles relative to conventional ones.
  • the core shell particle of the present invention is chemically and physically active.
  • the particle advantageously combines chemo-physical targeting and cargo retention capability. Accordingly, the core- shell particles of the invention are inherently suitable for applications that require a specific interaction between the particle and a target substrate.
  • the functional moiety F is selected from a hydroxyl group, an amino acid group, an amide group, an amine group, an imide group, a thiol group, a phosphate group, an epoxy group, an alkyl halide group, an isocyanate group, a hydrazide group, a semicarbazide group, an azide group, an ester group, a carboxylic acid group, an aldehyde group, a ketone group, a disulfide group, a xanthate group, a thiocyanate group, or a thiosulfate group.
  • the cross-linked polyelectrolyte core comprises an anionic polyelectrolyte, a cationic electrolyte, or a combination thereof.
  • the cross- linked polyelectrolyte core may comprise a polyelectrolyte selected from poly(acrylamide), poly(acrylic acid), poly(allylamine), poly(ethylenimide), poly(styrene sulfonate), poly(N-isopropylacrylamide), poly(diallyldimethylammonium chloride), and a combination thereof.
  • the core- shell particle of the invention may comprise additive species, which may be either core additive or shell additive species depending on whether they are provided in the cross-linked polyelectrolyte core or coordinated to the functional moiety, respectively. Depending on the nature of the additive species, they advantageously provide additional functionality to the core-shell particle of the invention.
  • the present invention also provides a method for preparing a core-shell particle, the method comprising the steps of:
  • the core template is advantageously larger and more mechanically stable than conventional polyelectrolyte core templates. Also, the resulting core-shell particle has improved mechanical stability over conventional core-shell particles.
  • the cross-linked polyelectrolyte core template may be provided by any means known to the skilled person.
  • the core template is synthesised via a water- organic solvent emulsion route. This allows for easy control of the reaction conditions and facile tuning of the core template morphology and composition.
  • the coating of the core template may be achieved by any means known to the skilled person.
  • the core template is coated by hydrolysis and condensation reactions of alkoxysilanes and functional alkoxy silanes.
  • alkoxysilanes and functional alkoxysilanes to provide a silica-based shell advantageously affords a high degree of chemical customisation of the silica-based shell.
  • the present invention also allows for the provision of intermediate layers between the core template and the silica-based shell.
  • the core-shell particle of the invention may include one or more intermediate layers between the core template and the silica-based shell, wherein the one or more intermediate layers are selected from an oppositely charged polyelectrolyte relative to the cross-linked polyelectrolyte core, a two dimensional anionic material such as graphene oxide, silica, calcium carbonate, metal nanoparticles of the kind described herein, a surfactant, or a combination thereof.
  • the one or more groups of formula -R-F covalently bound to the silica-based shell are introduced by promoting hydrolysis and condensation of functional alkoxysilanes comprising one or more groups of formula -R-F covalently bonded to a tetra-coordinated silicon atom.
  • the functional alkoxysilanes may be used together with alkoxysilanes for the provision of a homogeneous dispersion of functional moieties throughout the silica-based shell, or in a two-step approach in which alkoxysilanes are first condensed on the template core to form an initial silica-based surface, followed by condensation of the functional alkoxysilanes on the initial silica-based surface.
  • Figure 1 shows an optical micrograph of embodiment poly(acrylamide)-silica core-shell particles dispersed in water
  • Figure 2 shows diameter distribution of approximately spherical dried poly(acrylamide) template cores
  • Figure 3 shows Zeta-potential profiles of poly(acrylamide) cores, poly(acrylamide)-silica, and poly(acrylamide)/poly(acrylic acid)-silica core-shell particles measured at between pH 2-12 in 10 mmol/F NaCl,
  • AFM Atomic Force Microscope
  • Figure 11 shows a) phosphate ion release from 0.020 w/v% poly(allylamine)-silica core shell particle containing 360 mg/g P0 4 3- in water as a function of time, and b) a schematic of adsorption scenarios based on adsorption affinity between dissolved ions and cross- linked polyelectrolyte cores,
  • Figure 13 shows the magnetic response of dispersed poly(acrylamide)-silica core-shell particles having a core containing magnetite nanoparticles (3.0 mg/g dry) after settling for 10 minutes without (a) and in the presence (b) of an external magnetic field,
  • Figure 14 shows optical micrographs of the core-shell particles of Figure 13 moving under the influence of an external magnetic field within 6 seconds of applying the field
  • FIG 15 shows fluorescent micrographs of core-shell particles surface-functionalised with bovine serum albumin (BSA) tagged with fluorescein isothiocyanate (FITC),
  • BSA bovine serum albumin
  • FITC fluorescein isothiocyanate
  • Figure 16 shows mercapto-functionalised silica-PEI core-shell particles deposited (a) on a gold component of an electronic circuit board, and (b) on a pristine gold surface,
  • Figure 17 shows comparative values of adhesive force between mercapto-functionalised silica-PEI core-shell particles and a silicon substrate (left distribution), and between the same particles and a gold surface (right distribution),
  • Figure 18 shows effectiveness of gold extraction using mercapto-functionalised silica-PEI core-shell particles adsorbed on gold surfaces as a function of (a) time and (b) concentration of particles,
  • Figure 19 shows fragments of a printed circuit board component (a) in its pristine form, and (b) after gold extraction from the contact electrodes using mercapto-functionalised silica-PEI core-shell particles,
  • Figure 20 shows flutriafol release (%) from the alkyl-functionalised core-shell particles into water as a function of time
  • Figure 21 shows adsorption of perflurooctanoic acid (PFOA) into the core of silica— PEI core-shell particle adsorbent as a function of PFOA equilibrium concentration
  • Figure 22 shows PFOA concentration in contaminated soil before and after treatment with dilute sodium chloride solution (left) and mixture of dilute sodium chloride solution and silica— PEI core- shell particle adsorbent.
  • the present invention provides a core-shell particle.
  • the core-shell particle is a discrete subdivision of matter. Generally, the core-shell particle will range in size from fractions of nanometers (nm) to several units of millimetres (mm) as measured in terms of its largest dimension.
  • the particle of the invention is a“core-shell” particle, meaning that the particle comprises an inner core that is either wholly covered or otherwise surrounded by an outer shell layer. As a result of the core being either wholly covered or otherwise surrounded by the outer shell layer, the Young Modulus of the particle increases relative to the Young Modulus of the core absent the shell.
  • the core-shell particle of the invention has a largest size from fractions of nanometers (nm) to several units of millimetres (mm), there is no particular limitation as to the exact size of the core-shell particle.
  • the largest dimension of the core-shell particle is between about 1.0 nm to about 5 mm, between about 1.0 nm to about 1 mm, between about 10 nm to about 750 pm, between about 50 nm to about 750 pm, between about 100 nm and 750 pm, between about 100 nm and 500 pm, between about 100 nm and 250 pm, between about 100 nm and 100 pm, between about 250 nm and 100 pm, between about 500 nm and 100 pm, between about 750 nm and 100 pm, between about 1 pm and 100 pm, or between about 1 pm and 50 pm.
  • the core-shell particle is spheroidal in shape, such that its dimension can be measured in terms of a largest diameter.
  • the largest diameter of the core-shell particle is between about 1.0 nm to about 5 mm, between about 1.0 nm to about 1 mm, between about 10 nm to about 750 pm, between about 50 nm to about 750 pm, between about 100 nm and 750 pm, between about 100 nm and 500 pm, between about 100 nm and 250 mih, between about 100 nm and 100 mih, between about 250 nm and 100 mih, between about 500 nm and 100 mih, between about 750 nm and 100 mih, between about 1 mih and 100 mih, or between about 1 mih and 50 mih.
  • the core-shell particle of the invention is substantially spherical in shape such that its dimension can be measured in terms of a diameter.
  • the diameter of the core-shell particle is between about 1.0 nm to about 5 mm, between about 1.0 nm to about 1 mm, between about 10 nm to about 750 pm, between about 50 nm to about 750 pm, between about 100 nm and 750 pm, between about 100 nm and 500 pm, between about 100 nm and 250 pm, between about 100 nm and 100 pm, between about 250 nm and 100 pm, between about 500 nm and 100 pm, between about 750 nm and 100 pm, between about 1 pm and 100 pm, or between about 1 pm and 50 pm.
  • the core-shell particle of the invention comprises a cross-linked polyelectrolyte core.
  • a“polyelectrolyte” means a polymer having at least one ionic side group. Suitable examples of ionic side groups include -sulfonate groups, -ammonium groups, -imidazolium group, -amine groups, -amide groups, -imide groups, -carboxy groups, and -phosphonate groups.
  • the core-shell particle of the invention has a core that is either entirely made of cross-linked polyelectrolyte or a core in which a major component is a cross-linked polyelectrolyte.
  • the cross-linked polyelectrolyte core comprises from 51% to 100% of polyelectrolyte, from 75% to 100% of polyelectrolyte, from 80% to 100% of polyelectrolyte, from 85% to 100% of poly electrolyte, from 90% to 100% of polyelectrolyte, or from 95% to 100% of polyelectrolyte by weight.
  • the core may include any one or more components that are chemically compatible with the cross-linked poly electrolyte.
  • the core may include one or more polymer(s) other than the cross-linked polyelectrolyte. This can be advantageous for modulating the chemical character of the core.
  • the core may include a polymer having one or more hydrophobic moieties, the fraction of which may be tailored to tune the overall hydrophilic/hydrophobic character of the core.
  • the core may include one or more additives species that confer the particle additional chemical and/or physical properties.
  • the core may include one or more additives species of the kind disclosed herein.
  • the polyelectrolyte has at least one ionic side group, there is no limitation to the nature of the polyelectrolyte.
  • the polyelectrolyte is selected from an anionic polyelectrolyte, a cationic polyelectrolyte, or a combination thereof.
  • the polyelectrolyte may be selected from poly (acrylamide), poly(acrylic acid), poly(allylamine), poly(ethylenimine), poly(styrene sulfonate), poly(N- isopropylacrylamide), poly(diallyldimethylammonium chloride), and a combination thereof.
  • the polyelectrolyte is selected from poly(acrylamide), poly(allylamine), poly(acrylic acid), poly(ethylenimine), poly(methacrylic acid), and a combination thereof.
  • suitable combinations of polyelectrolytes for use in the invention include poly(acrylamide)/poly(acrylic acid), and poly(methacrylic acid)/poly(acrylamide).
  • the polyelectrolyte is a cross-linked poly electrolyte.
  • the polyelectrolyte being“cross-linked” is meant that at least two polyelectrolyte chains or at least two locations of a polyelectrolyte chain are covalently connected to one another through a cross-linking agent, resulting in a three-dimensional open-lattice molecular structure. Since the polyelectrolyte is cross-linked, the resulting core-shell particle can be larger in size relative to corresponding core-shell particles in which the polyelectrolyte is not cross-linked, and preserve mechanical robustness despite its larger size.
  • the core is advantageously insoluble in a polar solvent and can be preserved in dry state. This significantly facilitates its handling and shelf-life for practical purposes.
  • the polyelectrolyte is cross-linked, there is no limitation as to the nature of the cross-linking agent used to achieve the cross-linking. Suitable examples of cross-linking agents include those described herein.
  • the cross-linked polyelectrolyte is in the form of a gel.
  • gel is meant a cross-linked system that presents as a solid, jelly-like material that, when in steady-state, exhibits no flow and can support its own weight when in steady-state.
  • a typical characteristic of a gel is its ability to swell as a result of accumulation of fluid within its volume.
  • the cross-linked polyelectrolyte core can therefore be used as a carrier to entrain species.
  • the cross-linked polyelectrolyte core may comprise core additive species.
  • core additive species can be provided in the polyelectrolyte core, there is no limitation to their chemical nature.
  • the core additive species are selected from nanoparticles, microparticles, ions, bio-molecules, cells, and a combination thereof.
  • the cross-linked polyelectrolyte core comprises nanoparticles.
  • nanoparticle is meant a discrete subdivision of matter ranging in size from fractions of nanometers (nm) to hundreds of nanometers (nm) as measured in terms of its largest dimension.
  • the nanoparticles are magnetic nanoparticles.
  • the expression“magnetic nanoparticles” refers to nanoparticles possessing a permanent or induced dipole moment.
  • magnetic nanoparticles suitable for use in the present invention include those made of a ferromagnetic, a ferromagnetic, an anti-ferromagnetic, a paramagnetic, or a super-paramagnetic material.
  • core-shell particles suspended in a fluid medium can be easily isolated from the fluid medium by the application of an external magnetic field, for example with a magnet.
  • suitable magnetic nanoparticles include nanoparticles made of a metal material, a magnetic material, a magnetic alloy, or a combination thereof.
  • the metal material may include at least one selected from Pt, Pd, Ag, Cu, and Au.
  • the magnetic material may include at least one selected from Co, Mn, Fe, Ni, Gd, Mo, M3O4, MM 2O4, and M x M y , wherein M and M' are each independently Co, Fe, Ni, Mn, Zn, Gd, or Cr, and 0 ⁇ x ⁇ 3 and 0 ⁇ y ⁇ 5.
  • the magnetic alloy may include at least one selected from CoCu, CoPt, FePt, CoSm, NiFe, and NiFeCo.
  • the magnetic particles comprise particles made of at least one metal oxide selected from oxides of iron, oxides of manganese, oxides of cobalt, oxides of zinc, oxides of nickel and oxides of copper.
  • the magnetic nanoparticles are magnetite (Fe 3 04) nanoparticles.
  • the magnetic nanoparticles can be provided in the cross-linked polyelectrolyte core, there is no limitation as to their size or shape.
  • the magnetic particles have a maximum dimension of from about 1 nm to about 500 nm, from about 1 nm to about 100 nm, from about 1 nm to about 50 nm, or from about 1 nm to about 10 nm.
  • the magnetic nanoparticles can be provided in the cross-linked polyelectrolyte core, there is no limitation as to their concentration in the cross-linked polyelectrolyte core.
  • the concentration of magnetic particles in the core is between about 0.1 wt% and about 15 wt%, between about 0.5 wt% and about 15 wt%, between about 1 wt% and about 15 wt%, between about 1 wt% and about 10 wt%, or between about 1 wt% and about 5 wt%.
  • the cross-linked polyelectrolyte core comprises Quantum Dots (“QDs”).
  • QDs Quantum Dots
  • semiconductor QDs semiconductor nanoparticles having a maximum dimension that is smaller than the exciton Bohr radius of the specific semiconductor forming the QDs
  • C-QDs carbon nanoparticles comprising amorphous to nanocrystalline cores with predominantly graphitic or turbostratic carbon (sp 2 carbon) or graphene and graphene oxide sheets fused by diamond-like sp 3 hybridised carbon insertions
  • semiconductor QD In a semiconductor QD the electronic excitation levels of the semiconductor material are confined in three dimensions, resulting in the material having electronic properties between those of the bulk semiconductor and a discrete molecule. As a result, semiconductor QDs shows size-dependent opto-electronic properties.
  • a core shell particle of the invention comprising semiconductor QDs would emit light at specific wavelengths depending on the nature of the semiconductor QDs and their size.
  • semiconductor QDs are provided in the form of monodisperse nanoparticles.
  • the semiconductor QDs comprise monodisperse semiconductor QDs having a maximum dimension of between about 1 nm to about 50 nm, between about 1 nm to about 25 nm, between about 1 nm to about 10 nm, between about 1 nm to about 7 nm, or between about 1 nm to about 5 nm.
  • the semiconductor QDs can emit light along a narrow range of wavelengths.
  • suitable core-type semiconductor QDs for use in the invention include CdS QDs, CdSe QDs, ZnS QDs, ZnSe QDs, InAs QDs, HgS QDs, ZnTe QDs, PbS QDs, PbSe QDs, CdTe QDs, InP QDs, CuInS QDs, and a combination thereof.
  • suitable core-shell semiconductor QDs for use in the invention include (according to a core/shell notation) CdS/ZnS QDs, CdSe/ZnS QDs, CdSe/ZnSe QDs, CdSe/CdS QDs, InAs/CdSe QDs, CdS/HgS QDs, CdS/CdSe QDs, and ZnSe/CdSe QDs, ZnTe/CdSe QDs, CdTe/CdSe QDs, CdS/ZnSe QDs, and a combination thereof.
  • the alloyed QDs may be selected from alloyed core-shell semiconductor QDs such as CdSei- x S x /ZnS, CdSei- x Te x /ZnS, Cdi- x In x S/ZnS and a combination thereof.
  • C-QDs are provided in the form of monodisperse nanoparticles.
  • the C-QDs comprise monodisperse C-QDs having a maximum dimension of between about 1 nm to about 50 nm, between about 1 nm to about 25 nm, between about 1 nm to about 10 nm, between about 1 nm to about 7 nm, or between about 1 nm to about 5 nm. Examples of C-QDs and details of their synthesis may be found in Shi Ying Lim, et al., “Carbon quantum dots and their applications” , Chem. Soc. Rev., 2015, 44, 362, the content of which is incorporated herein in its entirety.
  • the semiconductor QDs or C-QDs can be provided in the cross-linked polyelectrolyte core, there is no limitation as to their amount.
  • the amount of semiconductor QDs or C-QDs in the cross-linked polyelectrolyte core is between about 0.1 and about 10 wt %, between about 0.1 wt% and about 5 wt%, or between about 0.1 wt% and about 1 wt%.
  • the cross-linked polyelectrolyte core comprises microparticles.
  • microparticles is meant a discrete subdivision of matter ranging in size from hundreds of nanometers (nm) to hundreds of micrometers (pm) as measured in terms of its largest dimension.
  • suitable microparticles include microparticles made of magnetic materials described herein. As long as the magnetic microparticles can be provided in the cross- linked polyelectrolyte core, there is no limitation as to their size or shape. In some embodiments, the magnetic microparticles have a maximum dimension of from about 100 nm to about 500 pm, from about 1 pm to about 100 pm, from about 1 pm to about 50 pm, or from about 1 pm to about 10 pm.
  • the magnetic microparticles can be provided in the cross-linked polyelectrolyte core, there is no limitation as to their concentration in the cross-linked polyelectrolyte core.
  • the concentration of magnetic microparticles in the core is between about 0.1 wt% and about 15 wt%, between about 0.5 wt% and about 15 wt%, between about 1 wt% and about 15 wt%, between about 1 wt% and about 10 wt%, or between about 1 wt% and about 5 wt%.
  • the cross-linked polyelectrolyte core comprises an ionic species.
  • the“ionic species” of these embodiments is in addition to the at least one ionic side group of the poly electrolyte.
  • The“ionic species” of these embodiments will be understood to be an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
  • the ionic species can be provided in the cross-linked polyelectrolyte core, there is no particular limitation to the nature of the ionic species.
  • suitable ionic species include (i) potassium ions (K + ), (ii) nitrogen-containing ions such as nitrate ions (N0 3 ) and ammonium ions (NH 4 + ), (iii) phosphorous -containing ions such as phosphate ions (P0 4 3 ), hydrogen phosphate ions (HP0 4 2_ ), and dihydrogen phosphate ions (H 2 P0 4 ), (iv) sulfur-containing ions such as sulphate (S0 4 2 ) and thiosulfate (S2O2 2 ), (v) iodide (G), (vi) ions of transition metals belonging to the d-block of the Chemical Periodic Table, examples of which include iron(II,III), copper (I, II), gold(I,III), and silver(I)), (vii)
  • the core-shell particle of the invention can advantageously function as slow release fertiliser to promote plant growth since the ionic species can advantageously desorb from the cross-linked polyelectrolyte core to be released into the external environment.
  • nitrogen-containing ions may be present in an amount of at least about 15 mg/g, at least about 40 mg/g, at least about 55 mg/g, at least 80 mg/g relative to the weight of the core-shell particle. In some embodiments, nitrogen-containing ions are present in an amount of up to about 350 mg/g, up to about 250 mg/g, or up to 150 mg/g relative to the weight of the core-shell particle.
  • the core of the core-shell particle comprises from about 15 mg/g to about 350 mg/g, from about 40 mg/g to about 250 mg/g, or from about 55 mg/g to 150 mg/g of nitrogen relative to the weight of the core-shell particle.
  • the core-shell particle promotes plant growth
  • the amount of phosphorous -containing ions may be present in the core of the core-shell particle of the present invention.
  • phosphorous-containing ions may be present in an amount of at least about 100 mg/g, at least about 150 mg/g, at least about 200 mg/g, or at least about 250 mg/g relative to the weight of the core-shell particle.
  • the core of the core-shell particle comprises phosphorous-containing ions in an amount of up to about 500 mg/g, up to about 400 mg/g, or up to about 350 mg/g.
  • the core of the core-shell particle comprises from about 50 mg/g to about 500 mg/g, from about 100 mg/g to about 400 mg/g, or from about 150 mg/g to about 350 mg/g of phosphorous-containing ions relative to the weight of the core-shell particle.
  • the core-shell particle promotes plant growth
  • potassium ions may be present in an amount of at least about 10 mg/g, at least about 20 mg/g, at least about 30 mg/g, at least about 40 mg/g.
  • the core of the core-shell particle comprises potassium in an amount of up to about 250 mg/g, up to about 200 mg/g, or up to about 175 mg/g.
  • the core of the core-shell particle comprises from about 10 mg/g to about 250 mg/g, from about 20 mg/g to about 200 mg/g, from about 30 mg/g to 175 mg/g of potassium relative to the weight of the core-shell particle.
  • the cross-linked polyelectrolyte core comprises one or more plant regulator compounds.
  • the plant regulator compounds are selected from pesticides (such as herbicides, insecticides, and fungicides), plant growth regulators, and a combination thereof.
  • the core- shell particle of the invention finds application as agro-chemical regulator for the selective growth inhibition of unwanted plants.
  • the core- shell particle functions as intended, there is no limitation to the amount of plant regulator compounds.
  • the plant regulator compounds may be present in an amount of between about 0.05 wt% to about 5 wt%, between about 0.12 and about 1.0 wt %, between about 0.12 wt% and about 0.4 wt% relative to the weight of the core-shell particle.
  • Suitable herbicides include s-triazine type herbicides such as atrazine and 2- chloro-4-ethylamino-6-isopropylamine-s-triazine, sulfonylureas such as trifloxysulfuron, nicosulfuron, metsulfuron, amidosulfuron, sulfosulfuron and triasulfuron; triazines such as simazine and atrazine; dinitroanilines such as prodiamine, pendimethalin and oryzalin; triazolinones such as sulfentrazone, thiencarbazone and carfentrazone; pyridines such as dithiopyr and triclopyr; ureas such as diuron and fenuron; difenyl ethers such as formesafen and oxyfluorofen; chloroacetamides such as acetochlor and s-metolachlor; cyclohe
  • Example of suitable insecticides include abamectin, cyanoimine, acetamiprid, thiodicarb, nitromethylene, nitenpyram, clothianidin, dinotefuran, fipronil, lufenuron, pyripfoxyfen, thiacloprid, fluxofenime, imidacloprid, thiamethoxam, chloranthraniliprole, beta cyfluthrin, lambda cyhalothrin, fenoxycarb, diafenthiuron, pymetrozine, diazinon, disulphoton, profenofos, furathiocarb, cyromazin, cypermethrin, tau-fluvalinate, tefluthrin, spinosad, etofenprox, carbosulfan, propaphos, permethrin, bensultap, benfuracarb, ry
  • the pesticides are selected from abamectin, thiodicarb, cyanoimine, acetamiprid, nitromethylene, nitenpyram, clothianidin, dinotefuran, fipronil, thiacloprid, imidacloprid, thiamethoxam, chloranthraniliprole, beta cyfluthrin, lambda cyhalothrin, tefluthrin, and a combination thereof.
  • fungicides include azoxystrobin, bitertanol, carboxin, Cu 2 0, cymoxanil, cyproconazole, cyprodinil, dichlofluamid, difenoconazole, diniconazole, epoxiconazole, fenpiclonil, fludioxonil, fluoxastrobin, fluquiconazole, flusilazole, flutriafol, furalaxyl, guazatin, hexaconazole, hymexazol, imazalil, imibenconazole, ipconazole, kresoxim-methyl, mancozeb, metalaxyl, mefenoxam, metconazole, myclobutanil, oxadixyl, pefurazoate, penconazole, pencycuron, prochloraz, propiconazole, pyroquilone, ( ⁇
  • fungicides include azoxystrobin, propiconazole, difenoconazole, fludioxonil, thiabendazole, tebuconazole, metalaxyl, mefenoxam, myclobutanil, fluoxastrobin, tritaxonazole and trifloxystrobin.
  • azosystrobin fludioxonil and mefenoxam.
  • Suitable plant growth regulators include paclobutrazol and trinexapac-ethyl, and acibenzolar-S-methyl.
  • the cross-linked polyelectrolyte core further comprises a bio molecule.
  • bio-molecule and its variants comprise any compound isolated from a living organism, as well as synthetic or recombinant analogs or mimics, derivatives, mutants or variants and/or bioactive fragments of the same.
  • the bio-molecule can be a protein, a peptide, a nucleic acid, a nucleotide, or an amino acid.
  • bioactivity can include the selective binding of an antibody to an antigen, the enzymatic activity of an enzyme, and the like. Such activity can also include, without limitation, binding, fusion, bond formation, association, approach, catalysis or chemical reaction, optionally with another bio-molecule or with a target molecule.
  • the cross-linked polyelectrolyte core comprises a bio-molecule
  • concentration of the bio-molecule in the cross-linked polyelectrolyte core can include a range of between about 0.01 and about 100 mg/g, between about 0.01 and about 75 mg/g, between about 0.1 and about 50 mg/g, between about 0.1 and about 25 mg/g, between about 0.2 and about 25 mg/g, between about 0.25 and about 25 mg/g, between about 0.25 and about 20 mg/g, between about 0.25 and about 15 mg/g, between about 0.25 and about 10 mg/g, and between about 0.025 and about 1.5 mg/g.
  • the bio-molecule is an amino acid.
  • amino acid refers to an organic acid containing both a basic amine group (NH 2 ) and an acidic carboxyl group (COOH).
  • the expression is used in its broadest sense and may refer to an amino acid in its many different chemical forms including a single administration amino acid, its physiologically active salts or esters, its combinations with its various salts, its tautomeric, polymeric and/or isomeric forms, its analogue forms, its derivative forms, and/or its decarboxylation products.
  • amino acids useful in the invention comprise, by way of non-limiting example, Agmatine, Beta Alanine, Arginine, Asparagine, Aspartic Acid, Cysteine, Glutamine, Glutamic Acid, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, PhenylBeta Alanine, Proline, Serine, Threonine, Tryptophan, Tyrosine, and Valine.
  • the bio-molecule is a protein.
  • protein refers to a polymer of amino acid residues and to variants and synthetic analogues of the same. Thus, these terms apply to amino acid polymers in which one or more amino acid residues is a synthetic non-naturally occurring amino acid, such as a chemical analogue of a corresponding naturally occurring amino acid, as well as to naturally-occurring amino acid polymers.
  • protein also embraces an enzyme.
  • the protein may be selected from therapeutic or prophylactic proteins. These may include plasma proteins, hormones and growth factors, extracellular proteins, and protein antigens for vaccines. They may also be selected from structurally useful proteins for use in cosmetics and foods. Examples of plasma proteins include, but are not limited to Albumin (HSA), haemoglobin, thrombin, fibronectin, fibrinogen, immunoglobulins, coagulation factors (FX, FVIII, FIX)). Examples of extracellular proteins (and in some case these are also described as structural proteins) include, but are not limited to collagen, elastin, keratin, actin, tubulin, myosin, kinesin and dynein.
  • plasma proteins include, but are not limited to Albumin (HSA), haemoglobin, thrombin, fibronectin, fibrinogen, immunoglobulins, coagulation factors (FX, FVIII, FIX)).
  • extracellular proteins include, but are not limited to collagen, e
  • hormones and growth factors include, but are not limited to insulin, EGF, VEGF, FGF, insulin like growth factor, androgens, and estrogens.
  • antigen proteins include, but are not limited to ovalbumin (OVA), keyhole limpet hemocyanin and bovine serum albumin (BSA) and immunoglobulins.
  • OVA ovalbumin
  • BSA bovine serum albumin
  • Proteins that can be used in the invention include enzymes.
  • enzyme refers to a protein originating from a living cell or artificially synthesised that is capable of producing chemical changes in an organic substance by catalytic action.
  • Enzymes are industrially useful in many areas such as food, textiles, animal feed, personal care and detergents, bioremediation and catalysis. In these application areas, conservation of conformation and activity, bioavailability and release profile and the adoption of an encapsulation carrier all play some role in their industrial utility. Enzymes are also useful in biomedical devices and sensors, owing to their high selectivity. Examples of enzymes used in the food industry include, but are not limited to pectinases, renin, lignin- modifying enzymes, papain, lipases, amylases, pepsin and trypsin.
  • enzymes used in the textile industry include, but are not limited to endoglucases, oxidases, amylases, proteases cellulases and xylanases.
  • enzymes used in the biomedical/sensor industry include, but are not limited to dehydrogenases, lipases, horse radish peroxidase (HRP), urease and RNA or DNA enzymes such as ribonuclease.
  • the bio-molecule is a nucleic acid.
  • nucleic acid refers to polymeric macromolecules, or large biological molecules, essential for all known forms of life which may include, but are not limited to, DNA (cDNA, cpDNA, gDNA, msDNA, mtDNA), oligonucleotides (double or single stranded), RNA (sense RNAs, antisense RNAs, mRNAs (pre -mRN A/hnRN A) , tRNAs, rRNAs, tmRNA, piRNA, aRNA, RNAi, Y RNA, gRNA, shRNA, stRNA, ta-siRNA, SgRNA, Sutherland RNA, small interfering RNAs (siRNAs), double-stranded RNAs (dsRNA), short hairpin RNAs (shRNAs), piwi- interacting RNAs (PiRNA), micro RNAs (
  • the nucleic acid molecule comprises from about 8 to about 80 nucleobases (i.e. from about 8 to about 80 consecutively linked nucleic acids).
  • nucleic acid molecules of 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
  • the cross-linked polyelectrolyte core comprises a cell.
  • the term‘cell’ means a biological unit comprising a membrane-bound cytoplasm. That is, a cell suitable for use in the invention is a cell provided with all structural features of a living cell, i.e. a whole cell. In that context, such a cell may be, for example, a eukaryotic cell or a prokaryotic cell, including a genetically-modified cell, a cell containing the same genetic material as a naturally-occurring cell, a cell from a line of cells, or one isolated from an organism.
  • the cell is a eukaryotic cell.
  • a eukaryotic cell comprises genetic material that is enclosed within a nuclear envelope (also known as nuclear membrane, nucleolemma or karyotheca). Multiple eukaryotic cells can organise into complex structures and are the characteristic cells of animals (including humans), plants, fungi, and Protista. Accordingly, the cell may be a eukaryotic cell selected from an animal cell, a plant cell, a fungi cell, and a Protista cell.
  • the cell is a prokaryotic cell.
  • a prokaryotic cell lacks a nuclear envelope separating genetic material from the cytoplasm.
  • prokaryotic cells include bacterial cells (i.e. unicellular microorganisms belonging to the Domain Bacteria ), and Archea cells (i.e. unicellular microorganisms belonging to the Domain Archea).
  • the cell may be a prokaryotic cell selected from a bacterial cell, and an Archea cell.
  • the core-shell particle of the invention comprises a silica-based shell.
  • the shell being a“silica-based” is meant that a main component of the shell is silica, i.e. silicon dioxide (Si0 2 ).
  • the silica may be microporous, mesoporous or microporous.
  • microporous the silica has molecular defects with an average size of less than 2 nm (micropores). These may derive from discontinuities and defects of the silica molecular structure due to a portion of silicon atoms being covalently mono-, di-, or tri- coordinated with an element other than oxygen, for example carbon.
  • the silica has interconnecting voids and orifices with an average size in the range of 2-50 nm (mesopores).
  • the silica has interconnecting voids and orifices with an average size larger than 50 nm (macropores).
  • the role of silica in the hybrid materials is twofold: providing a chemical environment with versatile functionality, and preventing physical degradation of the core template.
  • the silica-based shell has covalently bound thereto one or more groups of formula -R-F, wherein R is an organic group and F is a functional moiety.
  • R is an organic group and F is a functional moiety.
  • the silica-based shell “having covalently bound thereto” one or more groups of formula -R-F is meant that the organic group R of the one or more groups of formula -R-F is covalently bonded to a silicon atom within the silica molecular structure.
  • R being an“organic group” is meant that R includes at least one carbon atom.
  • R may therefore be an alkyl group, an alkenyl group, an aryl group, or a carbocyclyl group.
  • alkyl used either alone or in compound words, describes a group composed of at least one carbon and hydrogen atom, and denotes straight chain, branched or cyclic alkyl, for example C1-20 alkyl, e.g. Ci-io or Ci- 6 .
  • straight chain and branched alkyl examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t- butyl, n-pentyl, l,2-dimethylpropyl, 1,1 -dimethyl-propyl, hexyl, 4-methylpentyl, 1- methylpentyl, 2-methylpentyl, 3-methylpentyl, l,l-dimethylbutyl, 2,2-dimethylbutyl, 3,3- dimethylbutyl, l,2-dimethylbutyl, l,3-dimethylbutyl, l,2,2-trimethylpropyl, 1,1,2- trimethylpropyl, heptyl, 5-methylhexyl, l-methylhexyl, 2,2-dimethylpentyl, 3,3- dimethylpentyl, 4,4-dimethylpentyl, l,2-dimethylpent
  • cyclic alkyl examples include mono- or polycyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and the like. Where an alkyl group is referred to generally as‘propyl’, butyl’ etc., it will be understood that this can refer to any of straight, branched and cyclic isomers where appropriate.
  • R is a linear alkyl group having from 1 to 20 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl, and the like.
  • alkenyl denotes groups formed from straight chain, branched or cyclic hydrocarbon residues containing at least one carbon to carbon double bond including ethylenically mono-, di- or polyunsaturated alkyl or cycloalkyl groups as previously defined, for example C2-20 alkenyl (such as C2-10 or C2-6).
  • alkenyl examples include vinyl, allyl, l-methylvinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, l-pentenyl, cyclopentenyl, l-methyl-cyclopentenyl, l-hexenyl, 3-hexenyl, cyclohexenyl, l-heptenyl, 3-heptenyl, l-octenyl, cyclooctenyl, l-nonenyl, 2-nonenyl, 3-nonenyl, l-decenyl, 3- decenyl, l,3-butadienyl, l,4-pentadienyl, l,3-cyclopentadienyl, l,3-hexadienyl, 1,4- hexadienyl, l,3-cyclohexadienyl, l,4-cyclohex
  • aryl denotes any of single, polynuclear, conjugated and fused residues of aromatic hydrocarbon ring systems (e.g. C 6 -24 or Ce-is).
  • aryl include phenyl, biphenyl, terphenyl, quaterphenyl, naphthyl, tetrahydronaphthyl, anthracenyl, dihydroanthracenyl, benzanthracenyl, dibenzanthracenyl, phenanthrenyl, fluorenyl, pyrenyl, idenyl, azulenyl, chrysenyl.
  • the aryl group is selected from phenyl and naphthyl.
  • carrier includes any of non-aromatic monocyclic, polycyclic, fused or conjugated hydrocarbon residues, preferably C3-20 (e.g. C3-10 or C3-8).
  • the rings may be saturated, e.g. cycloalkyl, or may possess one or more double bonds (cycloalkenyl) and/or one or more triple bonds (cycloalkynyl).
  • Suitable examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclopentenyl, cyclohexenyl, cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cyclooctatetraenyl, indanyl, decalinyl and indenyl.
  • a carbocyclyl group may be optionally substituted by one or more optional substituents as herein defined.
  • the term ‘carbocyclylene’ is intended to denote the divalent form of carbocyclyl. In some embodiments, the carbocyclyl moieties are 5-6-membered or 9-10 membered ring systems.
  • F being a“functional” moiety is meant that F contains at least one element other than carbon and hydrogen.
  • F contains an element selected from oxygen, nitrogen, sulphur, bromine, chlorine, fluorine, phosphorous, boron, and aluminium.
  • F is selected from a hydroxyl group, an amino acid group, an amide group, an amine group, an imide group, a thiol group, a phosphate group, an epoxy group, an alkyl halide group, an isocyanate group, a hydrazide group, a semicarbazide group, an azide group, an ester group, a carboxylic acid group, an aldehyde group, a ketone group, a disulfide group, a xanthate group, a thiocyanate group, or a thiosulfate group.
  • silica-based shell has covalently bound thereto more than one groups of formula -R-F, those groups may be the same or different.
  • the silica-based shell has groups of formula -R-F that are identical to one another. In other embodiments, the silica-based shell has groups of formula -R-F, each of which having R and F independently selected from any one of the respective moieties described herein.
  • the core-shell particle of the invention comprises shell additive species coordinated to the functional moiety F. Provided they can coordinate to the functional moiety F, there is no limitation to the nature of the shell additive species.
  • the shell additive species coordinated to the functional moiety may be nanoparticles. Accordingly, in some embodiments the core-shell particle further comprises nanoparticles coordinated to the functional moiety. Advantageously, by having nanoparticles coordinated to the functional moiety the core- shell particle of the invention acquires the chemical and physical characteristics of the coordinated nanoparticles.
  • the core- shell particle of the invention further comprises metal nanoparticles coordinated to the functional moiety.
  • metal nanoparticles include Au nanoparticles, Ag nanoparticles, Cu nanoparticles, Pt nanoparticles, Pd nanoparticles, Ru nanoparticles, Re nanoparticles, and a combination thereof.
  • the core-shell particle further comprises Au nanoparticles coordinated to the functional moiety.
  • the nanoparticles are selected from magnetic nanoparticles and QDs as described herein.
  • An aspect of the present invention also relates to a method for preparing a core- shell particle.
  • a step of the method requires providing a cross-linked polyelectrolyte core template.
  • the polyelectrolyte may be synthesised by promoting polymerisation of any suitable polyelectrolyte precursor known to a skilled person. Provided it can be used to synthesise a polyelectrolyte, there is no particular limitation to the chemical nature of the polyelectrolyte precursor.
  • suitable polyelectrolyte monomer precursors include acrylamide, allylamine hydrochloride, acrylic acid, ethylene imine, 4- styrenesulfonic acid sodium salt, N-isopropylacrylamide, and diallyldimethylammonium chloride.
  • cross-linking of a polyelectrolyte may be achieved by any means known to the skilled person.
  • the polyelectrolyte may be exposed to a cross- linking agent.
  • cross-linking agent is meant a chemical compound that is capable to establish a covalent link between at least two discrete polyelectrolyte chains or at least two locations of a polyelectrolyte chain, resulting in the at least two polyelectrolyte chains or the at least two locations of a polyelectrolyte chain to be covalently bonded through the cross-linking agent.
  • the cross- linking agent has two or more reactive groups, each of which may be made to react with an ionic side group of a polyelectrolyte.
  • cross-linking the polyelectrolyte it is advantageously possible to obtain polyelectrolyte template cores that are larger than conventional polyelectrolyte template cores in which the polyelectrolyte is not cross-linked.
  • the cross-linked polyelectrolyte affords the core superior mechanical stability relative to conventional polyelectrolyte core templates. This results in a number of advantages.
  • cross-linked polyelectrolyte core templates are insoluble in conventional solvents, making them extremely easy to handle either in suspended form (e.g. in a solvent) or in dry state.
  • cross-linked polyelectrolyte cores have significantly longer shelf life relative to conventional poly electrolyte core templates.
  • cross-linking agent is effective in cross-linking the polyelectrolyte, there is no particular limitation to the chemical nature of the agent.
  • suitable cross-linking agents include N,N’-methylenebisacrylamide, epichlorohydrin, bis(2- methacryloyl)oxyethyl disulphide, l,4-bis(4-vinylphenoxy)butane, divinylbenzene, p- divinylbenzene, glycerol ethoxylate, glycerol ethoxylate-co-propoxylate, hexa(ethylene glycol) dithiol, 2-[8-(3-hexyl-2,6-dioctylcyclohexyl)octyl]pyromellitic diimide oligomer, 2-[8-(3-hexyl-2,6-dioctylcyclohexyl)octyl] pyromellitic diimide oligomer
  • the polyelectrolyte template core of the invention is synthesised in a water/organic solvent emulsion system, water being the suspended phase and the organic solvent the continuous phase.
  • a skilled person would be aware of suitable procedures in that regard.
  • suitable polyelectrolytes precursors are dispersed in the water phase in the presence of a polymerisation initiator and a cross-linker of the kind described herein.
  • polyelectrolyte forms there is no particular limitation to the amount of polyelectrolytes precursors used in the synthesis.
  • the polyelectrolyte precursor is dispersed in the water phase at precursor-to-water weight ratio of between about 1:100 and about 1: 1.
  • the polymerisation initiator may be selected from ammonium persulphate, azobisisobutyronitrile, potassium persulfate, tetramethylethylenediamine, and a combination thereof.
  • the polymerisation initiator is used in an initiator-to-polyelectrolyte precursor weight ratio of from about 1:100 to about 1:2.
  • cross-linking agent-to-polyelectrolyte precursor weight ratio is from about 1:100 to about 1:5.
  • the method of the present invention also requires the coating of the core template with a silica-based shell. Provided the coating results in a silica-based shell as described herein, there is no particular limitation to how this is achieved.
  • the silica-based shell is provided by promoting hydrolysis and condensation reactions of alkoxysilanes and functional alkoxysilanes, which results in hydrolysed alkoxysilanes and hydrolysed functional alkoxysilanes condensing around the template core to form a silica-based shell of the kind described herein.
  • the alkoxysilanes and the functional alkoxysilanes are pre-hydrolysed (or partially pre-hydrolysed) in a medium separate from the medium containing the core template before are made to condense around the template core.
  • alkoxysilane used in isolation is meant compounds that contain one to four organic groups covalently bonded to a silicon atom through an oxygen atom, as opposed to being covalently bonded directly to the silicon atom.
  • the alkoxysilanes may be selected from (1) tetraalkoxysilanes, (2) trialkoxy silanes, (3) dialkoxysilanes, (4) monoalkoxysilanes, (5) trialkoxy silanes, or a combination thereof, respectively represented by the following formulae (1), (2), (3), (4) and (5):
  • R 1 0 3 Si— R 5 — S OR 1 ⁇ (5), wherein each of R 1 , R 2 , R 3 and R 4 independently represents an organic group R of the kind described herein, and R 5 represents a divalent hydrocarbon group having 1 to 20 carbon atoms. In some embodiments, R 1 , R 2 , R 3 , and R 4 are the same organic group.
  • Example of specific alkoxysilanes compounds of this type include methyltriethoxysilane (MTES), phenyltriethoxysilane (PTES), diethyldiethoxysilane, methyltrimethoxysilane (MTMS), dimethyldimethoxysilane, phenyltrimethoxysilane (PTMS), vinyltrimethoxysilane (VTMS), vinylriethoxysilane (VTES), tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetrapropoxysilane (TPOS), tetrabutoxysilane (TBOS), and a combination thereof.
  • MTES methyltriethoxysilane
  • PTES phenyltriethoxysilane
  • MTMS methyltrimethoxysilane
  • VTES vinyltrimethoxysilane
  • TMOS tetramethoxysilane
  • TEOS tetrae
  • “functional alkoxysilanes” is meant compounds that contain one to three organic groups covalently bonded to a silicon atom through an oxygen atom, and at least one to three groups of formula -R-F covalently bonded directly to the silicon atom, as appropriate such that the silicon atom is tetra-coordinated.
  • the functional alkoxysilanes are selected from functional trialkoxy silanes, functional dialkoxysilanes, functional monoalkoxysilanes, and a combination thereof, respectively represented by the following formulae (6)-(ll):
  • each of R 1 , R 2 , R 3 and R 4 independently represents an R group of the kind described herein, and each of F, F’, and F” is independently selected from a hydroxyl group, an amine group, an amide group, a thiol group, a phosphate group, an epoxy group, an alkyl halide group, an isocyanate group, a hydrazide group, a semicarbazide group, an azide group, an ester group, a carboxylic acid group, an aldehyde group, a ketone group, a disulfide group, a xanthate group, a thiocyanate group, and a thiosulfate group.
  • R 1 , R 2 , R 3 and R 4 are the same organic group.
  • F, F’, and F are the same functional moiety.
  • Examples of specific functional alkoxysilanes compounds suitable for use in the present invention include 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, 3- isocyanatopropyl triethoxysilane, 3-isocyanatopropyl trimethoxysilane, 3-azidopropyl triethoxysilane, 3-azidopropyl trimethoxysilane, 3-thiolpropyl trimethoxysilane (or 3- mercaptopropyl trimethoxysilane or trimethoxysilyl propanethiol), 3-thiolpropyl triethoxysilane (or 3-mercaptopropyl triethoxysilane or triethoxy silyl propanethiol), 3- cyanopropyl trimethoxysilane, 3-cyanopropyl triethoxysilane, N-(2-aminoethyl)-3- aminopropyl trimethoxy
  • the silica-based shell is provided by exposing the core template to a mixture of pre-hydrolysed alkoxysilane and a pre-hydrolysed functional alkoxysilane, in which case the step of coating the core template with a silica-based shell is contemporaneous to the step of introducing one or more groups of formula -R-F covalently bound to the silica-based shell.
  • pre-hydrolysed alkoxysilanes are first condensed on the core template, and functional alkoxysilanes are subsequently added to the condensed alkoxysilanes.
  • the functional alkoxysilanes can either be pre-hydrolysed before being added to the condensed alkoxysilanes, or hydrolysed in-situ directly on the condensed alkoxysilanes.
  • Pre-hydrolysis of alkoxysilanes and functional alkoxysilanes can be performed by exposing alkoxysilanes and functional alkoxysilanes, either together or separately, to water in presence of an acid or a base. Details of available pre -hydrolysis procedures are available in David Levy, Marcos Zayat, The Sol-Gel Handbook: Synthesis, Characterization, and Applications , 3 Volume Set, September 2015 (ISBN: 978-3-527- 33486-5), the content of which is incorporated herein in its entirety). In some embodiments, the alkoxysilanes and functional alkoxysilanes are pre-hydrolysed by the addition of and acid, for example hydrochloric acid.
  • each gram of alkoxysilane or functional alkoxysilanes is made to react with from 1 to 250 pl of a 1 M solution of hydrochloric acid.
  • the weight ratio of alkoxysilanes to core template is between about 1:1,000 to about 1:1, between about 1:750 to about 1:1, between about 1:500 to about 1:1, between about 1:250 to about 1:1, between about 1:100 to about 1:1, between about 1:75 to about 1:1, between about 1:50 to about 1:1, between about 1:25 to about 1:1, between about 1:10 to about 1:1, between about 1:5 to about 1:1, between about 1:5 to about 1:1, or between about 1:2 to about 1:1.
  • the weight ratio of functionalised alkoxysilanes to core template is between about 1:1,000 to about 1:1, between about 1:750 to about 1:1, between about 1:500 to about 1:1, between about 1:250 to about 1:1, between about 1:100 to about 1:1, between about 1:75 to about 1:1, between about 1:50 to about 1:1, between about 1:25 to about 1:1, between about 1:10 to about 1:1, between about 1:5 to about 1:1, between about 1:5 to about 1:1, or between about 1:2 to about 1: 1.
  • the method of the invention further comprises coordinating shell additive species to the functional moiety of the silica-core shell.
  • the shell additive species are selected from a nanoparticle, a microparticle, a bio-molecule, and a combination thereof, of the kind described herein.
  • a skilled person would be aware of synthetic procedures that can be adopted to coordinate the shell additive species to the functional moiety of the core-shell particle of the invention.
  • core-shell particles of the invention may be suspended in a solvent having the additive species dispersed therein.
  • the additive species may be added to a suspension of core shell particles of the invention.
  • the amount of the shell additive species relative to the amount of core-shell particles.
  • the weight ratio of additive species to core-shell particles may be about 1:1000 to about 1:20.
  • Hydrochloric acid (HC1, 32%), sodium hydroxide (NaOH, 99%) and epichlorohydrin (99%) were purchased from Chem- Supply (Australia).
  • Tris(hydroxymethyl)aminomethane hydrochloride (tris-HCl, 99%) was purchased from VWR lifescience.
  • Sodium tetrachloroaurate (III) trihydrate (99%), sodium acetate (98%) and l-ascorbic acid (99.7%) were purchased from BDH Chemicals.
  • Acetic acid (99.7%) and sulfuric acid (98%) were purchased from Ajax Finechem.
  • Trisodium citrate dihydrate (99%), sodium chloride (NaCl, 99.5%), disodium hydrogen phosphate (99%), sodium di hydrogen phosphate (99%), iso-propyl alcohol (99.5%) and ethanol (96%) were purchased from Merck Chemicals. Water was sourced from a Millipore Milli-Q water system (> 18.2 MW-cm). The acrylamide monomer was recrystallised from acetone before use, and all other chemicals were used without further purification.
  • Silica-based shell formation on core templates comprising poly(acrylamide) TEOS was hydrolysed by the addition of hydrochloric acid (1 mol/L, 20 pL) under stirring for 5 minutes before being left to phase separate.
  • hydrolysed TEOS (0.l-0.5g) was subsequently added to the suspension of poly(acrylamide) core templates and gently stirred for 24 hours to allow deposition to complete.
  • the hybrid material was centrifuged in cyclohexane (3x), iso-propanol (3x) and ultra-pure water (3x). Samples were either stored as aqueous dispersions under refrigeration or were freeze dried using a Labconco Freezone 2.5, and stored under an inert atmosphere prior to use.
  • Mercapto-functionalised silica was synthesised by the addition of 3-mercaptopropyl trimethoxysilane (MPTMS, 1.0 mL) to a silica-poly(acrylamide) dispersion in ethanol, which was then left gently stirring for 24 hours to allow the reaction to come to completion.
  • the dispersions were centrifuged, redispersed in water (3x) and refrigerated prior to use.
  • Sodium tetrachloroaurate (III) trihydrate (0.0198 g) was dissolved in water (45 mL) and brought to a rolling boil. Trisodium citrate dihydrate solution (1 w/v%, 5 mL) was added to the boiling solution and left for 5 minutes for the reaction to come to completion.
  • the colloidal suspension was cooled on ice.
  • the gold nanoparticle suspension (15-60 mL) was added to the core-shell particles functionalised with mercapto- groups (0.50 g dry basis) in order to produce a gold decorated core-shell particle dispersion, which was refrigerated prior to use.
  • UV-vis spectrophotometry was used to determine the concentration of Au nanoparticles (on a gravimetric basis) in the supernatant both prior to and following gold deposition, allowing quantification of the gold loading on the capsule surface.
  • Poly(allylamine)-silica core-shell particle synthesis Poly(allylamine hydrochloride)(0.50 g) and NaOH (0.05 g) were dissolved in water (1.0 g). Sorbitan monooleate (0.30 g) was dissolved in cyclohexane (10 mL). The aqueous phase was dispersed in the organic under stirring at 1000 RPM and epichlorohydrin (25 pL) added to the dispersion. The emulsion was left stirring for 4 hours to allow completion of the reaction. The deposition of the silica-based shell was subsequently performed via the method described in Example 2.
  • Samples for scanning electron microscopy (SEM) were freeze dried, dispersed on silicon, and coated in carbon (10 nm) prior to analysis with a dual beam FEI Quanta 3D FEG SEM equipped with an energy-dispersive X-ray spectroscopy (EDX) detector for elemental analysis.
  • Samples for transmission electron microscopy (TEM) were freeze dried, embedded in Struers epofix resin and cured at room temperature for 24 hours. Thin sections ( ⁇ 60 nm) were cut from the resin via a Reichert Ultracut S ultramicrotome and placed on a copper TEM grid prior to analysis with a FEI Tecnai G2 F20 S-TWIN FEG TEM.
  • Atomic force microscopy was undertaken to determine the size of the synthesised AuNPs using a JPK Nanowizard 3 Bioscience AFM.
  • a small quantity ( ⁇ 20 pL) of the AuNP dispersion was spin coated onto a glass slide prior to analysis. All images were recorded in air using intermittent contact mode with antimony doped silicon cantilevers (model NCHY) from Bruker Corporation.
  • the catalytic activity of the gold nanoparticle decorated microcapsule material was investigated by the oxidation of benzyl alcohol.
  • Benzyl alcohol (0.2 mol/L) and sodium hydroxide (0.3 mol/L) were dissolved in a methanol/water (50/50 v/v %) mixture.
  • gold-containing capsule suspension (0.25 g) was added to the alkaline alcohol mixture, heated to 60°C and the reaction was left to proceed for 4 hours. At the completion of the reaction, the liquid phase was recovered by centrifugation. In recycling tests, the catalytic material was washed with water (3x) before re-use.
  • the supernatant was analysed via reverse phase high performance liquid chromatography (HPLC) using an Agilent 1220 Infinity II LC (water/acetonitrile 40/60 v/v % solvent, Cis column) to isolate, identify and quantify the reaction products.
  • HPLC reverse phase high performance liquid chromatography
  • a phosphate buffer solution (0.10 mol/L P0 4 3 , 0.10 mol/L NaCl, pH 7.4) was prepared as an adsorbate stock.
  • An acetate buffer solution (0.10 mol/L, pH 5.0), a tris(hydroxymethyl)aminomethane hydrochloride (tris-HCl) buffer solution (0.10 mol/L, pH 8.5) and a NaCl solution (0.10 mol/L) were prepared as diluents.
  • Sample solutions were prepared by the addition of a diluent to the stock solution to provide a phosphate concentration range 10-10,000 mg/L for each diluent system.
  • poly(allylamine)-silica core-shell particles were loaded with phosphate ions by the method described above. Once the adsorbed amount was known, the core-shell particle suspension was settled by centrifugation, the supernatant discarded and the remaining solid freeze dried prior to use.
  • silica- poly(allylamine) with a known phosphate concentration (0.01 g) was dispersed in a sodium chloride solution (0.10 mol/L, 4 mL). The dispersion was left to equilibrate for 48 hours before a sample was taken, separated by centrifugation and the phosphate concentration of the supernatant analysed via the colorimetric method described above.
  • the molecular weight and dispersity are likely to lie in this range or between 1 X 10 6 — 1 X 10 7 g/mol.
  • the poly(acrylamide)-silica core- shell particle synthesis led to poly-disperse particles. Upon drying, the particles maintain their sphericity and were not seen to collapse. It was possible to disperse the material in a range of solvents, and the particles were observed to swell in aqueous solutions.
  • the dry core templates have a normal size distribution with a mean diameter of 24.9 pm, as shown in Figure 2.
  • FIG. 3 shows Zeta potential plots measured on poly(acrylamide) core templates, poly(acrylamide)-silica core-shell particles, poly(acrylic acid)-silica core-shell particles, and poly(acrylamide)/poly(acrylic acid)-silica core-shell particles.
  • Poly(acrylamide) core templates are formally uncharged over the pH range investigated (pKa ⁇ 15), and so the relatively small magnitude of its charge is unsurprising. After the addition of the silica-based shell, the magnitude of the surface charge on the material increases markedly. The relationship between pH and the zeta potential is representative of bulk silica, indicating its likely presence on the core-shell particle. Zeta potential measurements were also taken for the poly(acrylamide)/poly(acrylic acid)-silica core-shell particles, which exhibit zeta potentials reflective of their strongly poly-anionic and poly- cationic cores respectively. It is likely that the thin silica shell deposited is not sufficiently thick to completely mask the high charge of these core materials. Atomic Force Microscopy
  • poly(acrylic acid)/poly(acrylamide)-silica core-shell particle, and poly(allylamine)- silica core-shell particle) show similar appearance to the poly(acrylamide) material, indicating universality of the synthetic procedure.
  • the successful deposition of silica onto core templates comprising poly(allylamine) was confirmed via AFM imaging and indentation experiments. AFM revealed few distinct surface features present, and no obvious protrusions. In contrast, after the addition of TEOS the surface results covered with nanometer scale aggregates, indicating the likely deposition of silica, potentially with secondary nucleation at the shell surface.
  • the level of surface roughness may be due to the cationic nature of the core template surface, which may allow the condensation of silica through a base-catalysed pathway as opposed to the anionic pathway expected for silica condensation onto reference flat surfaces of poly(acrylamide) .
  • silica-based shell The role of silica-based shell is twofold: providing a chemical environment with versatile functionality, and preventing physical degradation of the core template.
  • the previous AFM analysis has shown that the presence of silica changes the surface of the materials, but has not elucidated the structural role of the silica.
  • indentation tests were undertaken using AFM to measure the compliance of capsules following silane addition.
  • Figure 4(a) indicates, the stiffness of the particles increased following the addition of the silica-based shell to the template core.
  • the indentation depth decreased from approximately 900 nm to 300 nm for a loading set-point of 10 nN.
  • Figure 4(b) displays the indentation data on axes that emphasise a linear relationship between the applied force and the elastic modulus as calculated by the Hertz equation. For a material fitting this model, the Young’s modulus can be obtained from the gradient of a linear function. Examination of the coefficient of determination of these functions indicates a good fit to the Hertz model across the indentation range investigated.
  • Nano-indentation experiments were also performed on poly(acrylic acid) -silica core- shell particles and poly(acrylamide)/poly(acrylic acid)-silica core-shell particles, with results shown in Figures 5(a,b) and 6(a, b). As those Figures indicate, the stiffness of the samples increases significantly upon the addition of the silica-based shell. The magnitude of the Young’s modulus increases from the core template to the silica coated polymers (3.5x) for poly(acrylamide)/poly(acrylic acid)-silica core-shell particles and 2.6x for poly(acrylic acid)-silica core-shell particles.
  • the similarity of the mechanical response between these materials provides an indication that the deposition of silica onto the polymer template occurs through a common mechanism that may be applied to an array of hydrophilic polymer templates, allowing the creation of a variety of hierarchal composites.
  • the sulfur species are located in the silica-based shell, indicating that the organo-silane deposits on the silica shell rather being incorporated within the core templates.
  • the EDX spectrum ( Figure 7a) collected for the particle survey indicated the presence of carbon, nitrogen, oxygen, and sulfur, as expected for this material.
  • thiol-functionalised alkoxysilane allows the adsorption of gold nanoparticles to the core-shell particle.
  • Gold nanoparticles show particularly interesting optical properties and have potential applications in a number of fields, from medicine to catalysis, primarily due to their localised surface plasmon resonance and energetic crystal faces. Adsorption and catalytic studies were undertaken to examine the potential of the material as a stable, yet chemically versatile support for a highly active, functional surface.
  • TEM micrographs were recorded of thin sections of the core-shell particles prepared by ultramicrotomy (the nominal thickness of a section was approximately 60 nm).
  • the gold nanoparticles are clearly visible in high concentration on the external layers of the silica-based shell and are not seen to aggregate.
  • the strong partitioning of gold to the thin band in the centre of this image in Figure 8(b) suggests a surface coating which is highly amenable to nanoparticle deposition, with no affinity for the cross-linked polyelectrolyte core (visible as the dark top-right region of the micrograph in Figure 8(b)) exhibited by the nanoparticles.
  • Figure 8c is a high magnification TEM micrograph of the gold nanoparticle-decorated shell, close examination of which reveals adsorption of particles with a crystalline and faceted structure. Interestingly, it appears that the particles remain on the surface of the shell, and the exposed gold surface may thus retain the characteristics of the deposited gold nanoparticles.
  • the catalytic activity of the gold nanoparticles decorating the core-shell particle was investigated to determine whether the deposited gold remained accessible.
  • the model catalytic reaction chosen was the oxidation of benzyl alcohol.
  • Figure 9(a) shows the conversion and selectivity of this reaction, indicating that the adsorbed gold indeed retains its chemical activity.
  • the rate of reaction was approximately zero order, and there appeared to be no decrease in the rate of reaction or the activity of the catalyst.
  • the reaction rate had slowed dramatically and aggregation of the catalyst supports was observed.
  • the gold-decorated core-shell particles could be recycled and reused at length if the reaction was kept below 70°C.
  • the reaction yield was relatively unchanged over the course of the first several cycles.
  • the subsequent decrease in yield was accompanied by physical changes to the core- shell particles.
  • the core- shell particles were observed to aggregate in solution, and the material appeared purple rather than the red colour previously observed.
  • the benzaldehyde yield remained constant throughout the tests, and the decrease can be entirely attributed to a decreased yield of benzoic acid, the product of the‘over-oxidation’ of the alcohol.
  • the aggregated gold nanoparticle-decorated core-shell particles could be redispersed and reused following the recovery protocol used for all tests.
  • Epichlorohydrin cross-linked poly(allylamine) is known to be a high capacity, selective adsorbent for phosphate ions.
  • the capacity for phosphate ion adsorption was tested across a range of concentrations.
  • the cross-linked polyelectrolyte core is an effective adsorbent with a maximum adsorption of 373 mg P0 4 3- (check it matches with proposed embodiment ranges) per gram of poly(allylamine)-silica core-shell particles. This corresponds to an adsorption of 0.354 mol/mol poly(allylamine), slightly above the expected charge stoichiometry.
  • Figure 12(c) is a release profile conducted over a period of 90 days for a poly(allylamine)- silica core- shell particle in a large volume of water (0.2 wt% solids). In the first several hours, approximately 10% of the adsorbed phosphate is released. Beyond this initial period, very little release (up to 12% recovery) was observed over the course of the experiment. This result suggests that there are two modes of phosphate binding.
  • the initially released phosphate appears to be loosely bound or becomes entrained within the cross-linked polyelectrolyte core during the adsorption phases of the experiment, and hence rapidly desorbs when dispersed in the dilute ‘release’ reservoir.
  • the more strongly bound phosphate ions do not desorb to a significant degree over the long timescale investigated, suggesting that the material has a high affinity for phosphate ions and will be a highly effective encapsulation agent.
  • Superparamagnetic iron oxide (magnetite) nanoparticles (6 nm, nominal) were dispersed within the poly(acrylamide) during synthesis of the poly(acrylamide) cross-linked polyelectrolyte core template, and the core template coated with a silica-based shell as described in Example 2.
  • the magnetic nanoparticles appear to be located within the matrix and provided the poly(acrylamide)- silica core- shell particles as a whole with a high degree of response to an applied external magnetic field.
  • Bovine serum albumin is a protein biomolecule widely used in the biological sciences. It can be readily functionalised with the fluorescent molecule fluorescein isothiocyanate (FITC), without compromising the protein structure or function. Use of the BSA-FITC conjugate provides a straightforward method to visualise BSA when dispersed in aqueous solution.
  • Poly(acrylamide)— silica core- shell particles were prepared in accordance with the procedure described in Examples 1 and 2. Following synthesis and purification, the particles were dispersed in water (10 w/v %). To this dispersion aminopropyl triethoxy silane (APTES, 0.5 v/v % to polymer) was added and left to react overnight. The dispersion was then centrifuged, with the supernatant discarded and redispersed in water (10 mL) three times before use.
  • APTES aminopropyl triethoxy silane
  • Glutaraldehyde solution 50 uL was added to the particle dispersion and left to react for 5 minutes under gentle stirring.
  • BSA-FITC solution (1 mg/L, 100 uL) was added and left 5 minutes to react.
  • the dispersion was strongly yellow coloured.
  • the dispersion was then centrifuged, the supernatant discarded, and redispersed in water (10 mF) three times before use.
  • Cors-shell particles loaded with known metal etchants and functionalised with metallophilic moieties can be used for the direct extraction of metals in either mining or e- waste recycling applications.
  • Poly(ethylenimine) (PEI, 25,000 g/mol, 99 %), tetraethoxysilane (TEOS, 99 %), (3- mercaptopropyl)-trimethoxysilane (MPTMS, 95 %), cyclohexane (99%), sorbitan monooleate (70 %), and sodium thiosulfate pentahydrate (99%) were purchased from Sigma Aldrich.
  • Hydrochloric acid 32 %), sodium hydroxide (NaOH, 99 %) and epichlorohydrin (99 %) were purchased from Chem-Supply (Australia).
  • Iso-propyl alcohol (99.5 %) and ethanol (96 %) were purchased from Merck Chemicals. Water was sourced from a Millipore Milli-Q water system (> 18.2 MW ah).
  • PEI 0.50 g
  • NaOH 0.05 g
  • Sorbitan monooleate 0.30 g
  • the aqueous phase was dispersed in the organic under stirring at 1000 RPM 25 and epichlorohydrin (25 pL) added to the dispersion to cross-link the polymer.
  • the emulsion was left stirring for 4 hours to allow completion of the reaction.
  • TEOS 1.0 g was hydrolysed by the addition of hydrochloric acid (1 mol/L, 20 pL) under stirring for 5 minutes before being left to phase separate.
  • hydrolysed TEOS 0.1-0.5 g was subsequently added to the PEI core suspension as described above and gently stirred for 24 hours to allow deposition to complete.
  • the hybrid material was centrifuged, redispersed and washed in cyclohexane (3x), iso-propanol (3x) and ethanol (3x).
  • Mercapto-functionalised silica-based shell was synthesised by the addition of MPTMS (1.0 mL) to a silica-PEI dispersion in ethanol, which was then left gently stirring for 24 hours to allow the reaction to come to completion.
  • the dispersions were centrifuged, redispersed in water (3x) and refrigerated prior to use. Thiosulfate adsorption
  • a thiosulfate solution (50 g/L S2O3) was prepared as an adsorbate stock.
  • Sample solutions were prepared by dilution with ultrapure water to provide standard solutions (10-10 000 mg/L, 1 mL).
  • the PEI-functionalised silica core-shell particles (0.20 g) were added as adsorbent to each solution, which were then shaken vigorously. The mixture was left to equilibrate for 30 minutes before being settled via centrifugation. The supernatant was diluted in water as appropriate and the residual sulfur concentration was determined via inductively coupled plasma - optical emission spectroscopy (ICP-OES) using a Perkin - Elmer Avio 200 ICP-OES.
  • ICP-OES inductively coupled plasma - optical emission spectroscopy
  • Samples for scanning electron microscopy were freeze dried, dispersed on silicon, and coated with iridium (2 nm thickness, nominal) prior to analysis 40 with a dual beam FEI Quanta 3D FEG SEM equipped with an energy-dispersive X-ray spectroscopy (EDX) detector for elemental analysis.
  • SEM scanning electron microscopy
  • Figure 16(a) shows an optical micrograph of a printed circuit board component, which contains a region of gold surrounded by a non-metallic region. The micrograph allows appreciating that the gold-containing region is nearly entirely saturated by the capsules, while coverage on the rest of the surface (darker area surrounding the shaped contact) is low and patchy.
  • Figure 16(b) shows an optical micrograph of the core-shell particles functionalised with mercapto-functional groups adsorbed on a flat pristine gold surface.
  • the image allows appreciating the affinity of the functionalised capsules for gold surfaces, showing a near monolayer of particles adhering to the surface.
  • Soft colloidal probe studies were subsequently undertaken using atomic force microscopy for direct measurement of the strength of the adhesion between gold surfaces and the functionalised capsules.
  • Figure 17 shows histogram values of the adhesion measured between a single core-shell particle adsorbed onto a gold and a silicon substrate, with significantly greater adhesion observed in the case of the adsorption on gold.
  • Figure 18 shows data for gold extraction as a function of time ( Figure 18(a)) and concentration of core-shell particles ( Figure 18(b)).
  • Figure 19 shows images of (a) a pristine fragment of an electronic circuit board showing gold contact electrodes, and (b) another fragment of the same board after gold extraction using mercapto-functionalised core-shell particles prepared as described in this example.
  • Microcapsule use in agricultural contexts has the potential to challenge existing formulations for controlled spatial and temporal delivery of high-value or toxic agro chemicals.
  • Simple modification of the polymer core of the core-shell particles of the invention to include a hydrophobic polymer group allowed encapsulation of the triazole- type fungicide flutriafol, which showed strong partitioning to the particle and slow release into an aqueous reservoir.
  • capsules could be made to adhere to plant leaf surfaces specifically, allowing targeted and slow foliar delivery of agro-chemicals.
  • TEOS 1.0 g was hydrolysed by the addition of hydrochloric acid (1 mol/L, 20 pL) under stirring for 5 minutes before being left to phase separate.
  • hydrolysed TEOS 0.1-0.5 g was subsequently added to the PEI suspension as described above and gently stirred for 24 hours to allow deposition to complete.
  • the hybrid material was centrifuged, redispersed and washed in cyclohexane (3x), iso-propanol (3x) and ethanol (3x).
  • Organo-functionalised silica was synthesised by the addition of dimethyldichloro silane (DMDCS) (1.0 mL) to a silica-polymer dispersion in ethanol, which was then left gently stirring for 24 hours to allow the reaction to come to completion. The dispersions were centrifuged, redispersed in water (3x) and refrigerated prior to use.
  • DDCS dimethyldichloro silane
  • Adhesion between the alkyl-functionalised capsules and leaf substrates was first measured directly by the deposition of a waxy leaf into an aqueous dispersion of the alkyl- functionalised capsules. After gently stirring of the mixture to ensure adequate diffusion of the capsules the leaf was washed under a high-pressure water stream for 30 seconds and under a nitrogen stream until dry. Following this, the leaf was examined via optical microscopy to determine the degree of surface coverage.
  • cuticle wax was stripped from leaves (10 g) by immersion in chloroform (100 mL), to produce a wax-containing chloroform solution. Wax coated glass slides were produced by spin coating this solution (60 sec, 5000 RPM, 100 pL) onto a clean glass slide.
  • the glass slide was immersed in the alkyl-functionalised particle dispersion, before washing with a high-pressure water stream for 30 seconds and dried under nitrogen.
  • the transparent, waxy substrate was then examined via optical microscopy to determine the extent of coverage.
  • a flutriafol dispersion (20 g/L, 10 mL) was prepared as an adsorbate stock.
  • the silica— polymer adsorbent (3.0 g) was added to the mixture and shaken vigorously. The mixture was left to equilibrate for 30 minutes before being settled via centrifugation. The supernatant was taken and the flutriafol concentration determined via high performance liquid chromatography (HPLC). Release studies were undertaken by redispersing the flutriafol- saturated silica— polymer material in ultrapure water (1.0 L) and periodically sampling the mixture.
  • Optical characterisation demonstrate high affinity of the alkyl-functionalised core-shell particles to adhere to the waxy leaf and model substrates, with a large proportion of the material still in place following aggressive treatment of the surfaces. Such treatments were designed to mimic a real use case, in which rainfall and high winds may affect capsule performance. The functionalisation proved to be effective in foliar chemical delivery.
  • Figure 20 shows flutriafol release (%) from the alkyl-functionalised core-shell particles into water as a function of time.
  • the delayed release observed from the capsule indicates the strong partitioning of the fungicide within the polymer core, highlighting the capability of the material for slow, sustained release of agro-chemicals.
  • PFAS Perfluro alkyl substance
  • an organic contaminant (Perfluro alkyl substance, PFAS) is absorbed into the core of core-shell particles.
  • PFAS Perfluro alkyl substance
  • pristine particles have been percolated through a PFAS contaminated medium (soil, biomass, et cetera), absorbing the contaminant as they travel, concentrating it within the particle for effective recovery and disposal, and allowing the use of the contaminated medium.
  • Poly(ethylenimine) (PEI, 25 000 g/mol, 99 %), tetraethoxysilane (TEOS, 99 %), (3- mercaptopropyl)-trimethoxysilane (MPTMS, 95 %), cyclohexane (99%), sorbitan monooleate (70 %), and sodium thiosulfate pentahydrate (99%) were purchased from Sigma Aldrich.
  • Hydrochloric acid 32 %), sodium hydroxide (NaOH, 99 %) and epichlorohydrin (99 %) were purchased from Chem-Supply (Australia).
  • Iso-propyl alcohol (99.5 %) and ethanol (96 %) were purchased from Merck Chemicals. Water was sourced from a Millipore Milli-Q water system (> 18.2 MW-crn).
  • PEI 0.50 g
  • NaOH 0.05 g
  • Sorbitan monooleate 0.30 g
  • the aqueous phase was dispersed in the organic under stirring at 1000 RPM 25 and epichlorohydrin (25 pL) added to the dispersion to cross-link the polymer.
  • the emulsion was left stirring for 4 hours to allow completion of the reaction.
  • TEOS 1.0 g was hydrolysed by the addition of hydrochloric acid (1 mol/L, 20 pL) under stirring for 5 minutes before being left to phase separate.
  • hydrolysed TEOS 0.1-0.5 g was subsequently added to the PEI suspension as described above and gently stirred for 24 hours to allow deposition to complete.
  • the hybrid material was centrifuged, redispersed and washed in cyclohexane (3x), iso-propanol (3x) and ethanol (3x).
  • Aqueous flurocarbon adsorption A perflurooctanoic acid solution (PFOA, 10 mL, 200 mg/L) was prepared as an adsorbate stock. Sample solutions were prepared by dilution with ultrapure water to provide standard solutions (10-200 mg/L, 1 mL). The silica— PEI adsorbent (0.01 g) was added to each solution and shaken vigorously. The mixture was left to equilibrate for 30 minutes before being settled via centrifugation. The supernatant was taken and the PFOA concentration determined via liquid chromatography - mass spectrometry (LC-MS).
  • LC-MS liquid chromatography - mass spectrometry
  • a perflurooctanoic acid solution (10 mg/L, 200 mL) was added to a soil sample (Bayside, Melbourne AUS, 200g) and vigorously shaken to disperse. The mixture was dried under vacuum for 48 hours to produce a PFOA-contaminated soil (10 mg/kg).
  • Silica— PEI core- shell particles (0.1 g) were dispersed in a dilute sodium chloride solution (0.01 mol/L, 100 mL) to which a sample of PFOA-contaminated soil (50 g) was added. The mixture was shaken vigorously and left to equilibrate for 48 hours. The mixture was settled via centrifugation and the supernatant was taken for analysis via LC-MS.
  • the synthesised particles show a strong affinity for PFOA, as indicated in Figure 21. While the maximal adsorption capacity was not determined, the sorption behaviour observed indicates the initial core design has a suitably high affinity for PFOA. Through manipulation of the hydrophilic properties of the core, it should be possible to improve this affinity further.

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Abstract

L'invention concerne une particule noyau-enveloppe ayant a) un noyau de polyélectrolyte réticulé, et b) une enveloppe à base de silice ayant lié de manière covalente à celui-ci un ou plusieurs groupes de formule-R-F, dans laquelle R est un groupe organique et F est un fragment fonctionnel. L'invention concerne également un procédé de synthèse d'une particule noyau-enveloppe, le procédé comprenant les étapes consistant à : a) fournir un modèle de noyau de polyélectrolyte réticulé, b) enrober le gabarit de noyau avec une enveloppe à base de silice, et c) à introduire un ou plusieurs groupes de formule-R-F liés de manière covalente à l'enveloppe à base de silice, R étant un groupe organique et F étant un fragment fonctionnel.
PCT/AU2019/050475 2018-05-18 2019-05-17 Particules de type noyau-enveloppe WO2019218027A1 (fr)

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CN112920876A (zh) * 2021-01-30 2021-06-08 昆明钢铁控股有限公司 一种基于核壳结构SiO2@Graphene量子点的钛合金轧制润滑液及其制备方法
WO2022013243A1 (fr) * 2020-07-16 2022-01-20 Lifescientis Procédé de synthèse par chimie douce de particules de silice microniques
WO2023035193A1 (fr) * 2021-09-07 2023-03-16 山东大学 Engrais enrobé à libération lente et son procédé de préparation

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WO2022013243A1 (fr) * 2020-07-16 2022-01-20 Lifescientis Procédé de synthèse par chimie douce de particules de silice microniques
FR3112494A1 (fr) * 2020-07-16 2022-01-21 Lifescientis Procédé de synthèse par chimie douce de particules microniques
CN112920876A (zh) * 2021-01-30 2021-06-08 昆明钢铁控股有限公司 一种基于核壳结构SiO2@Graphene量子点的钛合金轧制润滑液及其制备方法
WO2023035193A1 (fr) * 2021-09-07 2023-03-16 山东大学 Engrais enrobé à libération lente et son procédé de préparation

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