KR102081391B1 - Anisotropic bimetal nanowires, bimetal nanowire-embedded polymer nanofibers, SERS substrates with the anisotropic bimetal nanowires, method thereof and its uses - Google Patents

Abstract

The present invention relates to polymer nanofibers embedded with anisotropic double metal nanowires and anisotropic double metal nanowires and uses thereof. The nanostructures in the present invention can be applied as metal nano probes and / or SERS substrates for surface-enhanced Raman scattering (SERS) sensing and / or image measurement.

Description

Anisotropic bimetal nanowires, bimetal nanowire-embedded polymer nanofibers, SERS substrates with the anisotropic bimetal nanowires, method enumerated anisotropic bimetal nanowires, bimetal nanowire embedded polymer nanofibers, bimetal nanowires and its uses}

The present invention relates to anisotropic bimetallic nanowires, bimetallic nanowire-embedded polymer nanofibers, a method of preparing the same, and uses thereof.

Raman spectroscopy has been studied for the detection and identification of small molecules, biomacromolecules, toxins, and pathogens. Specifically, surface enhanced Raman scattering (SERS) is of great interest for spectroscopic detection and identification of small molecules, nucleic acids, proteins and cells, mainly due to its ultra-high sensitivity, narrow bandwidth and significant multiplexing ability ( Non-Patent Document 1).

Bimetallic nanostructures, in the form of homogeneous hybrids or heterogeneous mixtures, are state of the art in a variety of applications due to their exceptional optical, catalytic and electrical properties depending on their size, shape and composition. It has been reported as a nanomaterial. Single metal nanostructures have inherent limitations due to symmetrically dispersed chemical functionality. In contrast, bimetal nanostructures are more valuable due to their multifunctionality given by each component. Although the dimensions and shape of single metal nanostructures are important parameters in controlling their properties, the composition of the bimetallic nanostructures, along with their dimensions and shapes, is also an important factor in controlling their properties. For example, bimetallic nanostructures provide more adjustable optical response than single metal nanostructures. The surface plasmon resonance (SPR) of the bimetallic nanostructures can be easily adjusted from the visible region to the near infrared region depending on Au and Ag composition, size, and shape. Au nanoparticles show two SPR peaks representing longitudinal and transverse modes, while bimetallic nanostructures composed of Au and Ag have four plasmon modes represented in longitudinal, transverse and two eight-pole modes. Indicates. Au-Ag bimetallic nanostructures with tunable optical reactions are attractive candidates for some applications such as biosensing, photons, and catalysis.

Homogeneous growth of metals mostly produces core-shell bimetallic nanostructures, while heterogeneous growth mostly forms anisotropic asymmetric bimetallic nanostructures. In particular, surface atoms are very important for modulating shape and growth control, and additional materials such as polymers, surfactants, passivants, adsorbents, chelating agents, and ligands can be used, which can be bound to the nanostructure surface. Can be. However, it is difficult to fully control heterogeneous growth to produce anisotropic asymmetric bimetallic nanostructures based on fine lattice mismatch. To date, studies of heterogeneous growth for producing bimetallic nanostructures have mostly been directed to growing secondary nanostructures on seed nanostructures such as iron or Pd nanoparticles or vice versa.

To date, studies on anisotropic asymmetric bimetallic nanostructures composed of Au-Ag nanostructures are insufficient. Thus, the present inventors continued the research and completed the invention for the double metal nanowire composed of Au-Ag.

1. K. Kneipp, Y. Wang, H. Kneipp, L. T. Perelman, I. Itzkan, R. R. Dasari, et al., "Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS)," Physical Review Letters, vol. 78, pp. 1667-1670, 03/03/1997.

It is an object of the present invention to provide anisotropic double metal nanowires composed of Au-Ag.

Another object of the present invention is to provide a metal nano probe for surface-enhanced Raman scattering (SERS) sensing and / or image measurement using an anisotropic double metal nanowire composed of Au-Ag according to the present invention.

Still another object of the present invention is to provide a method for preparing anisotropic double metal nanowires composed of Au-Ag.

Still another object of the present invention is to provide a polymer nanofiber embedded with the anisotropic double metal nanowire.

Still another object of the present invention is to provide a method for preparing polymer nanofibers in which the anisotropic double metal nanowires are embedded.

Still another object of the present invention is to provide a SERS metal nanoprobe using the polymer nanofibers.

Still another object of the present invention is to provide a SERS substrate including the double metal nanowires.

The present invention comprises an anisotropic bimetal nanowire (ABNW) consisting of Au (Au) and silver (Ag) compartment, the Au and Ag in the form of the gold compartment and the silver compartment alternately connected. to provide.

The double metal nanowire refers to a nanostructure consisting of a gold compartment and a silver compartment and connected to each other to form a line shape.

The anisotropy means that the properties of the material appear differently depending on the direction. Specifically, in the present invention, anisotropy refers to a compartment distinguished from each other by a gold compartment and a silver compartment, and thus exhibits different characteristics according to the type and shape of the metal.

The double metal nanowires may have a length of 20 nm to 20,000 nm.

Conventionally, nanowires were prepared while growing by reducing other metals to seed particles (for example, gold). That is, the seed nanoparticles contained in the finished nanowires have limited length growth. However, in the present invention, the gold compartment and the silver compartment, which are seeds, are alternately connected to each other to form length-adjustable nanowires by growing in length. Therefore, the length of the nanowires according to the present invention is longer than the conventional double metal nanowires.

The Raman reporter may be attached to the anisotropic double metal nanowire.

The Raman reporter means a Raman active organic compound, and any one widely used in the art may be used without limitation. Specific examples include Malachite green isothiocyanate (MGITC), rhodamine B isothiocyanate (RBITC), rhodamine 6G, adenine, 4-amino-pyrazole (3,4-d) pyrimidine, 2-ruoroadenine, N6-benzoyl Adenine, kinetin, dimethyl-allyl-amino-adenine, zeatin, bromo-adenine, 8-aza-adenine, 8-azaguanine, 4-mercaptopyridine, 6-mercaptopurine, 4-amino- 6-mercaptopyrazolo (3,4-d) pyrimindine, 8-mercaptoadenin, 9-amino-acridine and mixtures thereof, but is not necessarily limited thereto.

In another aspect, the present invention provides a metal nano probe for surface-enhanced Raman scattering (SERS) sensing and / or image measurement using the anisotropic double metal nanowires.

In the present invention, the term "probe" means a substance that can specifically bind to a target (target) substance to be detected, and means a substance that can confirm the presence of the target substance through the binding.

In the present invention, "nanoprobe" means a nano-sized probe.

In another aspect, the present invention provides a method for producing an anisotropic double metal nanowire consisting of Au-Ag comprising the following steps:

reducing agent; Gold precursors; And a seed solution containing a silver precursor;

Stirring by adding ammonium hydroxide to the seed solution; And

Silver simultaneously grows in both directions in the gold seed so that the gold and silver compartments are alternately connected to form double metal nanowires in which the gold (Au) -silver (Ag) compartments alternate;

step.

The concentration of ammonium hydroxide may be 0.002 to 2,000 mM.

If it is out of the above range, it may cause a problem that the length of the nanowire growth is not made well.

After forming the double metal nanowires, the method may further include adding a Raman reporter.

In another aspect, the present invention provides a polymer nanofiber embedded with an anisotropic double metal nanowire, wherein the anisotropic double metal nanowire of the present invention is contained within the crosslinkable polymer nanofiber.

The crosslinkable polymer is poly (acrylamide-coacrylic acid, poly (AAm-co-AA)], poly (N-isopropyl acrylamide-co-stearyl acrylate) [Poly (Nisopropyl acrylamide-co-stearyl acrylate), Poly (NIPAm-co-SA)], poly (N-isopropyl acrylamide-co-allylamine), poly ( NIPAM-co-AA), and poly (NIPAM-co-AA) having an acrylic moiety, but are not necessarily limited thereto.

Crosslinks may be formed between the polymers surrounding the metal nanowires to form a network between the metal nanowires and the polymer.

The double metal nanowires may have a length of 20 nm to 20,000 nm.

The anisotropic double metal nanowires may further include a Raman reporter in the polymer nanofibers embedded therein.

In another aspect, the present invention provides a metal nano probe for SERS image measurement using the polymer nanofiber embedded with the anisotropic double metal nanowire.

In another aspect, the present invention provides a method for producing polymer nanofibers embedded with anisotropic bimetallic nanowires comprising the following steps:

i) reducing agent; Gold precursors; And a seed solution containing a silver precursor;

ii) add ammonium hydroxide to the solution and stir

iii) Anisotropic metal nanowires composed of Au-Ag, in which silver grows in both directions simultaneously in the gold seed, where the gold compartments and the silver compartments are alternately connected, whereby the gold (Au) -silver (Ag) compartments alternately appear. and;

iv) inserting the anisotropic metal nanowires into the crosslinkable polymer nanofibers by using an electrohydrodynamic jetting (EHD) method to prepare the polymer nanofibers embedded with the anisotropic metal nanowires; And

v) crosslinking a polymer of said anisotropic metal nanowire embedded polymer nanofiber; step.

In step ii), the concentration of ammonium hydroxide may be 0.002 to 2,000 mM.

The crosslinkable polymer is as mentioned above.

In step v), the crosslinking may be a crosslinking which is physically, chemically or photoinitiated.

The crosslinkable polymer swells in a water-soluble environment and becomes a soft matrix to serve to fix the metal well. After electrohydrodynamic jettig ("EHD injection"), the polymer shell is cured at high temperatures to stabilize the metal nanostructures.

Crosslinking of the polymer can be accomplished through a variety of mechanisms including physical, chemical and photoinitiated crosslinking. When the crosslinkable polymer nanofibers embedded with the double metal nanowires of the present invention are heated or subjected to ultraviolet rays, crosslinks are formed between the polymers surrounding the metal nanowires to form a network between the metal nanowire-polymers. do. And, due to the formation of a network through such crosslinking is not dissolved in water.

In step iv), when the anisotropic double metal nanowires are placed in the crosslinkable polymer nanofibers, the double metal nanowires may be evenly distributed in the polymer through electrohydrodynamic injection control.

In another aspect the invention provides a SERS substrate comprising a bimetallic nanowire according to the invention.

The SERS substrate means a substrate capable of measuring SERS images.

The SERS substrate is made comprising the following steps:

The substrate,

A base substrate;

A metal thin film layer formed on the base substrate; And

And a bonding layer formed on the metal thin film layer, wherein the self-assembled monolayer (SAM) and the anisotropic double metal nanowire are bonded to each other.

The self-assembled monolayer and the anisotropic double metal nanowire are coupled through electrostatic interaction, and the anisotropic double metal nanowire is arranged between the self-assembled monolayer.

The self-assembled monolayer may be hydrophilic or hydrophobic. In the embodiment of the present invention, a hydrophobic monolayer was used.

Anisotropic double metal nanowires according to the present invention, the polymer nanofibers embedded with the double metal nanowires are metal nano probes for surface-enhanced Raman scattering (SERS) sensing and / or image measurement with improved Raman strength and / or It can be applied as SERS substrate.

1 is a schematic diagram of the synthesis of an EHD spray platform for (A) ABNW with different NM lengths and (B) ABNW into polymer nanofibers as SERS substrate for photon-based sensing. The silver compartments growing in both directions simultaneously in the gold seed reached other silver compartments, indicating that the ABNWs with different NW lengths consisted of alternating Au and silver compartments.
FIG. 2 shows the DLS profile of ABNW for investigating (A) UV / visible absorption spectra and (B) its plasmon absorption change and size distribution according to NH ₄ OH concentration in the range of 0.2 mM to 2 mM. (C) SERS spectra of ABNWs with different NW lengths.
3 is a TEM image and high-angle annular dark-field (HADDF) image of ABNW. (A, B) TEM image of Au seed nanoparticles when Au seeds were stabilized with PDDA with an average size of 42 nm. (CF) HAADF and TEM images of ABNWs with long NW lengths at different magnifications.
4 shows (A, B) HAADF and (C, D) TEM images of ABNW with shorter length
5 is a confocal laser scanning microscope (CLSM) image of ABNW-containing polymer nanofibers containing rhodamine 6G as fluorescent dye. Balls of nanofibers in (A, D) fluorescence image, (B, E) bright field image and (C, F) merged image, (A, B, C) dry state and (D, E, F) moisture state Focus laser scanning microscope image.
6 is a TEM image at different magnifications of (A, B) ABNW-embedded polymeric nanofibers.
FIG. 7 is a linear correlation between (A) Raman spectra and (B) relative Raman intensity and MGITC concentration as a function of MGITC concentration for SERS-based quantitative analysis.
8 is a schematic diagram for producing an ABNW-aligned gold pattern as a SERS substrate for SERS-based sensing applications. (A) Au seeds were prepared by AgNO ₃ -assisted polyol growth method. (B) ABNW was adsorbed onto anti-charged gold-patterns with self-assembled monolayers (SAM) through electrostatic interactions to form ABNW-aligned gold patterns, which were applied as SERS substrates for follow-up analysis. Schematic diagram.
9 is a linear correlation between (A) Raman spectra as a function of MGITC concentration for SERS-based quantitative analysis and (B) relative Raman intensity and MGITC concentration.

Hereinafter, the present invention will be described in more detail in the following examples. The following examples of the present invention are intended to embody the present invention but do not limit or limit the scope of the present invention. From the detailed description and examples of the present invention, those skilled in the art to which the present invention pertains can be easily inferred to be within the scope of the present invention. References cited in the present invention are also incorporated into the specification of the present invention.

Example 1 Materials

Diethylene glycol (DEG), gold (III) chloride hydrate (HAuCl ₄ .3H ₂ O), silver nitrate _{(AgNO 3, = 99.0%)} , poly (diallyl dimethyl ammonium chloride) (PDDA, MW: 400,000 - 500,000, 20% by weight in H ₂ O), ethanol (99.5%), aqueous ammonia (NH ₄ OH), malachide green isothiocyanate (MGITC), rhodamine 6G, Sigma-Aldrich (St. Louis, Missouri, USA) Purchased from Poly (acrylamide-co-acrylic acid, sodium salt), poly (AAm-co-AA) (MW: 200 kDa, 10% acrylic acid) was purchased from Polysciences. All glassware was washed with aqueous aqua regia (Regia, HCl: HNO ₃ , 3: 1) and then rinsed thoroughly with deionized water. Deionized water purified by Milli-Q (Millipore Water Purification Systems; EMD Millipore, Bedford, Massachusetts, USA) was used.

Example 2 Synthesis of Anisotropic Double Metal Au-Ag Nanowires from Au Seeds

DEG has the ability to reduce metal salts and freshly prepared solutions containing DEG. Dissolution of the reagents did not use sonication of the solution and strong vortexing. In a typical experiment, 0.25 M of 10 μL of HAuCl ₄ in water was added to 10 mL DEG and the solution was stirred for 2 minutes to yellow. Next, 250 μL PDDA was further introduced and the mixture was stirred for an additional 5 minutes. 0.004 mg of silver nitrate dissolved in 10 uL deionized water was dissolved in 2 mL DEG and introduced into a yellow mixture solution. The resulting mixture was placed in an oil bath without stirring and incubated at 210 ° C. for 30 minutes. The reaction was cooled to rt and 11.5 mL water was added. The resulting solution was used as Au seed solution for the preparation of anisotropic double metal Au-Ag nanowires (ABNW). Ammonium hydroxide at a final concentration of 0.2 mM to 2 mM was introduced into 1 mL of gold seed solution and stirred for 5 minutes. The resulting homogeneous solution was placed in an oven at 60 ° C. overnight. 2 mL water was added to the solution and centrifuged at 11,000 rpm to purify the ABNW of the pellet. Wash steps were performed twice and the resulting ABNW was resuspended in 1 mL water in the colloidal state for further characterization.

Example 3 Synthesis of ABNW-embedded Polymer Nanofibers

The prepared ABNW solution was centrifuged at 11,000 rpm and washed twice with deionized water to collect ABNW. Next, a 20.0 w / v% solution of poly (AAm-co-AA) was prepared in deionized water and rhodamine 6G as fluorescent dye was added to a final concentration of 0.05 w / v% of the polymer solution. A final concentration of 1.0 w / v% ABNW was suspended in the polymer solution without any significant precipitation. The ABNW suspension was then mounted in a 1 mL syringe (Becton-Dickinson, NJ, USA) equipped with a 21 gauge metal capillary (NanoNC, South Korea). An infusion syringe pump (Kd Scientific, USA) was used to maintain a continuous flow rate of 0.6 mL / hour. The positive electrode of the high voltage power supply (NNC HV 30, Nano NC, South Korea) was connected to the metal capillary attached to the syringe and the negative electrode to the collecting substrate of aluminum foil (Fisherbrand, USA). Depending on the environmental conditions, the distance separated between the electrodes varied in the range of 10 to 15 cm. The voltage varied between 14 and 16 kV and the continuous flow rate was maintained in the range of 0.60 to 0.80 mL / hour to uniformly produce ABNW-embedded (embedded) polymer nanofibers through EHD injection under ambient conditions. The microscope cover glass was placed on the surface of the aluminum collection substrate to characterize the ABNW-embedded polymer nanofibers using a confocal laser scanning microscope (CLSM) in a dry and expanded state. ABNW-containing polymer nanofibers were incubated at 175 ° C. for 12 hours to chemically stabilize the crosslinked poly (AAm-co-AA) chain by thermal imidization between amide and acrylic acid.

Example 4 Characterization

)에서 작동하는 Renishaw He-Ne 레이저가 장착된 Renishaw in Via 라만 현미경 시스템 (Renishaw, 영국)을 사용하여 모든 라만 특성분석을 수행하였다. Rayleigh 선을 수집 필터에 위치한 홀로그램 노치 필터를 사용하여 수집된 SERS 프로파일로부터 제거하였다. 라만 산란을 1 cm^-1의 분광 분해능의 전하-결합된 소자 (CCD) 카메라를 사용하여 수득하고, 모든 SERS 스펙트럼을 520 cm^-1 실리콘 선으로 보정하였다. MGITC로 표지된 ABNW의 콜로이드 용액을 작은 유리 모세관 (Kimble Chase, 일반 모세관, 소다 석회 유리, 내경: 1.1 - 1.2 mm, 벽: 0.2 ± 0.02 mm, 길이: 75 mm) 내에 탑재하였다. SERS 스펙트럼을 1초의 노출 시간 동안 수집하였으며, 이때 20x 대물 렌즈를 사용하여 608 내지 1738 cm^-1의 파장 수 범위에서 유리 모세관 상에서 레이저 스팟을 집중시켰다.To determine the colloidal properties of ABNW, dynamic light scattering (DLS) was performed using a Zeta sizer Nano ZS instrument (Malvern Instruments, Malvern, UK) equipped with a Ne-He laser with a wavelength of 633 nm and a scattering angle of 90 °. ) And zeta potential measurements were performed. The sample was diluted to 10: 1 with deionized water and the temperature was adjusted to 25 ° C. Using the UV-Visible Spectrometer (UV-1800, Shimachu, Japan), the ABNW's UV-, while varying the wavelength from 300 nm to 800 nm with a fixed slit width of 1 nm in a single 10 scan mode at a medium scan rate at 25 ° C Vis absorbance spectra were obtained. The baseline was adjusted using two empty cells filled with deionized water and its average size was obtained from at least 20 scan cycles. Zeta-potential measurements were also performed to determine their surface charge in deionized water. To characterize ABNW in polymer nanofibers, cover glass using ABNW-embedded polymer nanofibers using a confocal laser scanning microscope transmission electron microscope (CLSM, Leica TCS SP2 Leica, Germany) equipped with a 100 × objective oil immersion lens. Imaging directly from CLSM imaging was used to investigate if the fiber was formed into a uniform shape and JEM-2100F FE-STEM (JEOL, Germany) operating at an acceleration voltage of 80 to 200 kV was used to study the shape, size and compartmentalization of the ABNW. Transmission electron microscopy (TEM) analysis was performed. Samples were deposited on a 400 mesh copper grating coated with an ultra thin layer of carbon (Ted Pella, Inc. USA). In addition, a wavelength of 632.8 nm for an excitation source with a laser power of 12.5 mW (

All Raman characterizations were performed using the Renishaw in Via Raman microscope system (Renishaw, UK) equipped with a Renishaw He-Ne laser operating in. Rayleigh lines were removed from the collected SERS profile using a hologram notch filter located at the collection filter. Raman scattering was obtained using a charge-coupled device (CCD) camera with a spectral resolution of 1 cm ⁻¹ , and all SERS spectra were corrected with 520 cm ⁻¹ silicon lines. A colloidal solution of ABNW labeled with MGITC was mounted in a small glass capillary (Kimble Chase, normal capillary, soda lime glass, inner diameter: 1.1-1.2 mm, wall: 0.2 ± 0.02 mm, length: 75 mm). SERS spectra were collected for an exposure time of 1 second, using a 20 × objective lens to focus the laser spot on glass capillaries in the wavelength range of 608-1738 cm ⁻¹ .

Example 5 Manufacture of SERS Substrate

The glass substrate was washed with SPM (sulfuric acid: hydrogen peroxide = 4: 1) and SC-1 (ammonia water: hydrogen peroxide: distilled water = 1: 1: 5), and then titanium was sputtered onto the glass substrate. The photoresist was spin coated at 3000 rpm for 30 seconds. For 1 minute, light of 365 nm <λ <436 nm was irradiated at an intensity of 50 mJ / cm. The gold thin film was placed on a substrate and hydrophobic coating was performed for 30 minutes using TMPS. In acetone, the photoresist was removed using ultrasonic waves and washed with acetone and distilled water.

A 30 ml solution of 5 mM of 11-mercaptoundecanoic acid was prepared in ethanol. The gold micro array substrate was placed in 11-mercaptoundenoic acid solution and reacted for 12 hours. After self-assembly, the solution was removed and washed three times with ethanol.

 An aqueous solution containing ABNW was dropped by 10 uL into each spot of the SERS substrate and was dynamically bound for 4 hours using a shaker. The substrate, which had been bonded by electrostatic attraction, was washed three times with distilled water and then measured with Raman spectra.

Example 6 Trace Detection of MGITC Using ABNW-Built-in Polymer Nanofibers

Various solutions of MGITCs with varying concentrations ranging from 10 ⁻⁶ M to 10 ⁻⁴ M were prepared in water and ethanol mixtures with a volume ratio of 3: 1. ABNW-embedded polymeric nanofiber matrices deposited on aluminum foil were cut to appropriate sizes and immersed in MGITC solution for 30 minutes at different concentrations. The matrix was then washed thoroughly three times with deionized water and used for Raman scattering analysis. Raman spectra were collected for a 5 second exposure time under 633 nm He / Ne laser irradiation. All samples were analyzed under the same conditions. Raman spectra were corrected and used in quantitative analysis. Each sample was examined for at least 5 scan cycles and the generated SERS spectral values were averaged. Raman intensity at 1621 cm ⁻¹ corresponding to MGITC was then plotted against increasing concentration of MGITC.

1 (A) shows a schematic diagram of the synthesis of ABNWs with different NW lengths as SERS substrates for photon-based sensing. Au seeds were prepared by AgNO ₃ -assisted polyol growth method with a slight modification of the previously reported method (Yun Yang, et al. Controlled growth of Ag / Au bimetallic nanorods through kinetics control, Chemistry of Materials, 2012, 25 (1) ), 34-41). Synthesis reactions were carried out in DEG with high boiling point and sufficient polarity to readily dissolve the gold salt, silver salt and PDDA. More precisely, the Au seeds were found to be Au-Ag alloyed nanoparticles because a small amount of Ag was incorporated when preparing the Au seeds. To grow Ag sections on Au seeds, AgNO ₃ and DEG were used separately as Ag precursors and reducing agents and PDDA as capping agents. Ag shells were grown on Au seeds at 60 ° C. under ambient conditions to form ABNW. The silver compartments growing in both directions simultaneously in the gold seed reached other silver compartments, which began to grow in the other gold compartments, indicating that the ABNWs with different NW lengths consisted of alternating Au and silver compartments. This ABNW showed a longer length of about 2,000 nm, unlike conventional metal nanowires. 1 (B) shows a schematic of an EHD spray platform for encapsulating ABNW in polymer nanofibers. A homogeneous dispersion of ABNW in poly (AAm-co-AA) solution under aqueous conditions was filled into a plastic syringe with a stainless steel capillary. Upon application of a high voltage, a Taylor cone was formed and the jet stream was converted to ABNW-embedded poly (AAm-co-AA) nanofibers via EHD injection. These ABNW-embedded polymer nanofibers were applied as SERS substrates for follow-up analysis.

Figure 2 shows the DLS profile of the ABNW to investigate the UV / Visible light absorption spectrum and its plasmon absorption change and size distribution. Au seed absorbed visible light at 570 nm as a typical plasmon resonance of gold seeds. Absorbance below 500 nm showed precipitation of AgCl, Ag from AgNO ₃ and Cl ions from HAuCl ₄ . When preparing ABNW, no absorption of AgCl at shorter wavelengths occurred due to the reduction of Ag ions. In the growth phase of the silver compartment from the Au seed, AgCl was used as a precursor and aqueous ammonium was mixed with ABNW growth solution to initiate the reduction and growth process of AgCl. It was found that the concentration of ammonium hydroxide greatly influences the reduction rate of AgCl, which shows different UV absorption peaks. The DLS profiles of the ABNW showed different hydrodynamic magnitudes because the growth pattern of Ag on the Au seeds is controlled by the concentration of ammonium hydroxide. The final ammonium hydroxide concentration of 2 mM produced long nanowires having a length of about 1 to 2 mm. However, when the final concentration of ammonium hydroxide was 0.2 mM, the ABNW size was about 300 nm and the Ag growth rate was shown to change with the concentration of ammonium hydroxide. Therefore, ammonium hydroxide has been found to accelerate the rate of Ag formation because ammonia increases the basicity of the colloidal solution to make the DEG reduction process more powerful. In addition, as a Raman reporter, MGITC was introduced into a colloidal solution of ABNW to selectively adsorb onto the ABNW via coordination bonds with isothiocyanate groups (-N = C = S) to show hot spots along the length of the NW. The long ABNW showed a much improved SERS signal compared to the shorter signal. For reference, in the present embodiment, the long nanowire is 2000 nm and the short nanowire is 300 nm in size.

3 (A) and (B) show TEM and HAADF images of Au nanoparticles as seeds. This resulted in the counting of 30 randomly selected objects in the image, indicating that the average edge length of the Au seeds was 36.3 nm. 3 (C-F) shows HAADF and TEM images of longer ABNWs. Ammonium hydroxide with a final concentration of 2.0 mM produced a long NW and its average length was found to be about 2.5 mm.

4 (A-D) show TEM and HAADF images of ABNW with shorter lengths. Ammonium hydroxide with a final concentration of 2.0 mM produced shorter NW and its average length was found to be about 300 nm. If the Ag atoms form atoms via heterogeneous nucleation on the Au seed surface, these sites serve as active sites to induce Ag growth. When 0.2 mM ammonium hydroxide is used, the formation rate of Ag atoms is slowed down, resulting in a low concentration of Ag atoms in the nucleation step. On the other hand, when using 2.0 mM ammonium hydroxide, the formation speed of Ag atoms is high, and a large amount of Ag atoms for the growth of the silver compartment is generated in the nucleation step. As a result, different rates of formation of Ag atoms induced by ammonium hydroxide produced different concentrations of Ag atoms and made ABNW different in length.

Next, the ABNW was encapsulated in polymer nanofibers via EHD injection and then chemically stabilized through thermal imidization of poly (AAm-co-AA) meshes. Poly (AAm-co-AA), a water-soluble polymer, is widely used in the field of biotechnology in the form of spherical nanoparticles and nanofibers. Chemical crosslinking of these polymer nanofibers is an important step in increasing the resistance to dissolution in water for various follow-up assays. Many amide and carboxyl groups of the crosslinked poly (AAm-co-AA) chain form imide bonds between the polymer chains during thermal crosslinking at 175 ° C., making them stable under aqueous conditions. 5 shows confocal laser scanning microscopy (CLSM) images of ABNW-embedded polymer nanofibers in the dry and water-containing states of polymer nanofibers. 6 shows a TEM image of ABNW-embedded polymer nanofibers in the dry state of polymer nanofibers. ABNW particles could be identified in the polymer nanofibers. The analytes were used as SERS substrates for many chemical sensing because they can diffuse into the expanded polymer nanofiber structure and be physically or chemically adsorbed on the surface of the ABNW to measure Raman strength. SERS signal enhancement of MGITCs in ABNW-embedded polymer nanofibers was analyzed by dipping them into different concentrations of MGITCs as target molecules.

As shown in FIG. 7, selective adsorption of MGITC onto ABNW in polymer nanofibers via coordination bonds of isothiocyanate groups (-N = C = S) showed an increase in Raman signal depending on the concentration of MGITC. This is useful as a SERS substrate for follow-up analysis. In conclusion, these ABNW-embedded polymer nanofibers may be advantageous as cutting edge SERS substrates for photon-based chemical sensing.

8 is a schematic diagram for producing a gold pattern including ABNW as a SERS substrate for SERS-based sensing applications. ABNW, surfaced with positively charged PDDA, was adsorbed through electrostatic interaction on a gold-pattern with a negatively-charged self-assembled monolayer (SAM) on the gold substrate, forming an ABNW-aligned gold pattern. This is useful as a SERS substrate for trace analysis. In addition, as shown in FIG. 9, the selective adsorption of MGITC onto the ABNW-aligned gold pattern showed an increase in Raman signal with MGITC concentration, and this ABNW-aligned gold pattern was a SERS for photon-based chemical sensing. It can be applied as a substrate.

The present invention relates to (1) anisotropic bimetal nanowires (ABNWs) with different nanowire lengths, (2) synthesis of ABNW-embedded polymer nanofibers, their preparation and photon-based Sensing, and application of biomedical applications.

By precisely controlling and stretching the growth of Ag on the Au nanostructures, a seed was made, and ABNWs composed of Au and Ag compartments were alternately synthesized by easily fitting them to various lengths up to several mm. In the examples below, they exhibited good physicochemical- and optical properties and remained colloidal under aqueous conditions compared to isotropic metal nanowires such as gold and silver. By aligning the ABNW on a metal pattern, it can be used as a SERS substrate to quickly and sensitively detect target chemicals with very reproducible results. This is because these ABNWs exhibit significantly improved Raman strength compared to other isotropic metal nanowires. Aligning these positively charged ABNWs on the negatively charged gold pattern through electrostatic interactions increased the SERS strength, potentially leading to closer proximity between the ABNW itself and the ABNW and the patterned gold. Because.

In addition, the ABNW was encapsulated into polymer nanofibers by electrohydrodynamic (EHD) injection and chemically crosslinked the polymer mesh via thermal imidization. ABNW-embedded polymer nanofibers exhibit controlled SERS strength due to the introduction of different densities of ABNW into the nanofibers while maintaining chemical stability over a wide range of pH and ionic strengths. Controllable SERS signals, high sensitivity, physical- and chemical stability to several chemical environments, along with reproducible quantitative traceability analysis on a wide range of analytes, can make ABNW-embedded polymer nanofibers a state-of-the-art SERS substrate useful for trace detection applications.

Claims (20)

Consisting of a gold (Au) compartment and a silver (Ag) compartment,
The gold compartment and the silver compartment are alternately formed, consisting of Au-Ag which is connected linearly, anisotropic double metal nanowire having a length of 20 nm to 20,000 nm.
delete The method of claim 1,
The anisotropic double metal nanowires further comprises a Raman reporter, anisotropic double metal nanowires.
Metal nano probe for surface-enhanced Raman scattering (SERS) sensing and / or image measurement using the anisotropic double metal nanowire of claim 3.
reducing agent; Gold precursors; And a seed solution containing a silver precursor;
Stirring by adding ammonium hydroxide to the seed solution; And
Silver simultaneously grows in both directions in the gold seed so that the gold and silver compartments are alternately connected to form double metal nanowires in which the gold (Au) -silver (Ag) compartments alternate;
Method for producing an anisotropic double metal nanowire consisting of Au-Ag, comprising the step.
The method of claim 5,
The concentration of the ammonium hydroxide is 0.002 to 2,000 mM anisotropic double metal nanowire manufacturing method.
The method of claim 5,
After forming the double metal nanowire, further comprising the step of adding a Raman reporter, anisotropic double metal nanowire manufacturing method.
A polymer nanofiber having anisotropic double metal nanowires embedded therein, wherein the anisotropic double metal nanowires are contained within the crosslinkable polymer nanofibers.
The method of claim 8,
The crosslinkable polymer is poly (acrylamide-coacrylic acid, poly (AAm-co-AA)], poly (N-isopropyl acrylamide-co-stearyl acrylate) [Poly (Nisopropyl acrylamide-co-stearyl acrylate), Poly (NIPAm-co-SA)], poly (N-isopropyl acrylamide-co-allylamine), poly ( NIPAM-co-AA), and poly (NIPAM-co-AA) having an acrylic moiety, wherein the polymer nanofibers with anisotropic double metal nanowires are embedded.
The method of claim 8,
Cross-linking is formed between the polymer surrounding the metal nanowires to form a network between the metal nanowires and the polymer, polymer nanofibers embedded with anisotropic double metal nanowires.
The method of claim 8,
The double metal nanowires have a length of 20 nm to 20,000 nm, the polymer nanofibers embedded with anisotropic double metal nanowires.
The method of claim 8,
A polymer nanofiber embedded with anisotropic double metal nanowires further comprising a Raman reporter in the polymer nanofibers embedded with the anisotropic double metal nanowires.
A metal nano probe for surface-enhanced Raman scattering (SERS) image measurement using polymer nanofibers embedded with the anisotropic double metal nanowire of claim 12.
i) reducing agent; Gold precursors; And a seed solution containing a silver precursor;
ii) add ammonium hydroxide to the solution and stir
iii) Anisotropic metal nanowires composed of Au-Ag, in which silver grows in both directions simultaneously in the gold seed, where the gold compartments and the silver compartments are alternately connected, whereby the gold (Au) -silver (Ag) compartments alternately appear. and;
iv) inserting the anisotropic metal nanowires into the crosslinkable polymer nanofibers by using an electrohydrodynamic jetting (EHD) method to prepare the polymer nanofibers embedded with the anisotropic metal nanowires; And
v) crosslinking a polymer of said anisotropic metal nanowire embedded polymer nanofiber;
Including a step, anisotropic double metal nanowires embedded polymer nanofiber manufacturing method.
The method of claim 14,
In the step ii), the concentration of the ammonium hydroxide is 0.002 to 2,000 mM, an anisotropic double metal nanowire embedded polymer nanofiber manufacturing method.
The method of claim 14,
In the step iv), the crosslinkable polymer is poly (acrylamide-coacrylic acid, poly (AAm-co-AA)], poly (N-isopropyl acrylamide-co Poly (N-isopropyl acrylamide-co-stearyl acrylate), Poly (NIPAm-co-SA), poly (N-isopropyl acrylamide-co-allylamine) [poly (N-isopropylacrylamide-co -allylamine), poly (NIPAM-co-AA)], and poly (NIPAM-co-AA) having an acrylic moiety selected from the group consisting of polymer nanowires embedded with anisotropic double metal nanowires Fiber manufacturing method.
The method of claim 14,
In the step iv), when the anisotropic double metal nanowires into the crosslinkable polymer nanofibers, through the electrohydrodynamic spraying control, it is possible to evenly distribute the double metal nanowires in the polymer, anisotropic double Polymer nanofiber manufacturing method in which metal nanowires are embedded at different densities.
The method of claim 14,
In the step v), the cross-linking is a cross-linking made of physical, chemical or photoinitiated, anisotropic double metal nanowires embedded polymer nanofiber manufacturing method.
A SERS substrate comprising the bimetallic nanowire of claim 1.
The method of claim 19,
The substrate,
A base substrate;
A metal thin film layer formed on the base substrate; And
And a bonding layer formed on the metal thin film layer and having a self-assembled monolayer (SAM) and an anisotropic double metal nanowire bonded thereto.
The self-assembled monolayer and the anisotropic double metal nanowires are bonded through an electrostatic interaction, the anisotropic double metal nanowires are arranged between the self-assembled monolayer, SERS substrate.

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