KR102434781B1 - 3D Plasmonic Composite Structures with Ultrathin Hydrogel Skin - Google Patents

Abstract

a metal nanowire made of a first metal; and metal nanoparticles made of a second metal formed on the surface of the metal nanowire; And a hydrogel skin surrounding the nanostructure; a plasmonic composite structure comprising a is disclosed.

Description

3D Plasmonic Composite Structures with Ultrathin Hydrogel Skin

Ultra-thin hydrogel skin 3D plasmonic complex structure, in which an ultra-thin hydrogel skin having selective permeability with respect to size is coated on the surface of a plasmonic nanostructure to detect toxic molecules in a complex mixture without pretreatment using surface-enhanced Raman scattering It relates to a plasmonic complex structure.

Surface-enhanced Raman spectroscopy (SERS) technology amplifies molecular Raman signals through localized surface plasmon resonance (LSPR) effects in metal nanostructures. SERS technology is widely used for molecular analysis in various fields of biosensing, chemical analysis and environmental security testing as it enables fast, sensitive and non-destructive detection of molecular fingerprints. To achieve high signal enhancement to ensure high sensitivity, plasmonic nanostructures were designed with nanoscale features or nanogaps that act as plasmonic hotspots. Plasmonic hotspots can provide signal enhancement as high as 10 ¹⁰ through the LSPR coupling effect. Therefore, the controlled production of high-density hotspots is one of the most important design rules for developing high-sensitivity SERS chips and sensors.

Although the SERS technique greatly improves molecular Raman signals, it is still difficult to directly detect small target molecules in complex mixtures. Since the surface of the plasmonic nanostructure is easily contaminated by non-specific binding of large adhesion molecules such as proteins, adsorption of small target molecules is suppressed, resulting in a low signal-to-noise ratio. Therefore, while it is difficult to selectively detect target molecules in complex mixtures, they are of great importance for real-world molecular analysis of various samples including food, biological fluids (blood, saliva, etc.) and environmental fluids.

To achieve selective detection, plasmonic nanostructures are further designed to prevent non-specific binding of adhesion molecules or to selectively capture target molecules. For example, F. Sun et al. 7 described a metal surface modified with zwitterionic thiol (ie, N,N-dimethyl-cysteamine-carboxybetaine) and 4-mercaptobenzoic acid, Here, thiols prevent protein binding and benzoic acid groups enable selective capture of target fructose molecules (ACS Nano, 2015, 9, 2668-2676). Y. Jia et al. use liposome-encapsulated metal nanoparticles to detect small, unspecified target molecules in complex mixtures and exclude large molecules. In addition, metal nanoparticles can be loaded into a matrix of hydrogel microparticles using a microfluidic system to selectively allow injection of small molecules to the surface of plasmonic nanoparticles. However, liposomes and microgels are suspended in the sample solution for detection, making it difficult to separate them from the solution. In addition, in situ analysis is difficult because high magnification microscopy systems are required to measure the SERS signal of small objects. Therefore, designing SERS chips that enable fast and simple in situ detection of small molecules remains important but undeveloped.

Therefore, it blocks access to the plasmonic nanostructures through size-selective penetration of ultra-thin hydrogels that are large in size and interfere with detecting major toxic molecules in the mixture, and enhance the electromagnetic field in the nanogap of high-density nanostructures An object of the present invention is to provide a complex structure that can rapidly detect toxic substances without pretreatment.

In order to achieve the above object, in one aspect of the present invention

a metal nanowire made of a first metal; and metal nanoparticles made of a second metal formed on the surface of the metal nanowire; and

A plasmonic composite structure comprising a; hydrogel skin surrounding the nanostructure is provided.

In addition, in another aspect of the present invention

forming a metal coating layer made of a third metal on the surface of the metal nanowire made of the first metal;

forming a self-assembled monolayer (SAM) on the metal coating layer;

forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and

Forming a hydrogel skin surrounding the nanostructure in the nanostructure; is provided a method of manufacturing a plasmonic composite structure comprising a.

Furthermore, in another aspect of the present invention

Board; and

There is provided a substrate for surface-enhanced Raman spectroscopy for detecting a target material, including a plasmonic complex structure formed on the substrate.

In addition, in another aspect of the present invention

preparing a substrate;

forming a metal nanowire made of a first metal on the substrate;

forming a metal coating layer made of a third metal on the surface of the metal nanowire;

forming a self-assembled monolayer (SAM) on the metal coating layer;

forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and

There is provided a method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material, including the step of forming a hydrogel skin surrounding the nanostructure on the nanostructure.

Furthermore, in another aspect of the present invention

A method for detecting a target material using the substrate for surface-enhanced Raman spectroscopy for detecting the target material is provided.

The plasmonic composite structure according to the present invention blocks access to the plasmonic nanostructure through size-selective permeation of a large-sized material that interferes with the detection of major toxic molecules in the mixture, and the high-density nanostructure Through the enhancement of the electromagnetic field in the nanogap, trace amounts of toxic substances can be quickly detected without pretreatment.

Figure 1 is (a) a schematic diagram of the fabrication process of a hierarchical plasmonic nanostructure, (b) a scanning electron microscope (SEM) image of multi-stack Ag NWs, and the inset is 6 each containing multi-stack Ag NWs. A × 6 array of microwells is shown, (c, d) SEM images of multi-stack Au-Ag NWs decorated with Ag NPs with surfaces taken at two different magnifications, and (e) 633 nm calculated by FDTD simulation. The electric field distribution at the intersection of the crossed Ag NWs decorated with Ag NPs with respect to the wavelength of It shows the Raman spectrum of methylene blue (MB) measured in the nanostructure.
Figure 2 shows (a) a schematic diagram of a process for fabricating a plurality of microwell structures on a single substrate, (b) an image of a microwell array, and (c) four different spacings obtained by confocal microscopy. 3D topology of a micro-well array with
Figure 3 shows (a) SEM images of 3D multiple stacks of Ag NWs prepared by depositing 4 different volumes of Ag NW aqueous suspensions of 2 μl, 4 μl, 6 μl and 8 μl, (b, c) ( It shows the Raman spectrum of methylene blue (MB) measured in multiple stacks of a). 2 μl aqueous solution of 5 × 10 ^-6 M concentration of MB is deposited and dried, where the laser wavelength is 638 nm (b) and 785 nm (c) is used, respectively, and (d) Raman intensity at a Raman shift of 1628 cm ⁻¹ as a function of Ag NW suspension volume for two different wavelengths of lasers.
4 shows reflectance spectra measured in 3D multiple stacks of Ag NWs, Au-Ag NWs and Au-Ag NWs decorated with Ag NPs under three deposition conditions.
Figure 5 shows (ac) SEM images of hierarchical nanostructures composed of multi-layered Au-Ag NWs whose surface is decorated with Ag NPs, where Ag deposition conditions are (a) 20 nm, (b) 30 on a flat surface. nm and (c) 40 nm thick layers were used, (d) the size distribution histogram of spherical Ag NPs deposited on Au-Ag NWs for three different deposition conditions, and the solid line is a curve fitting the Gaussian equation. to be.
6 is an image showing the wetting state and contact angle when (ad) an ethanol solution (3 μl of a solution) containing PEGDA and water was deposited on an Ag-deposited PEN substrate, (a) 1.4 w/w% PEGDA, 0.6 w/w% water, and 98.0 w/w% ethanol, (b) 7.0 w/w% PEGDA, 3.0 w/w% water and 90.0 w/w% ethanol, (c) 14.0 w/w% PEGDA, 6.0 w /w% water, and 80.0 w/w% ethanol, and (d) 35.0 w/w% PEGDA, 15.0 w/w% water and 50.0 w/w% ethanol, wherein a solution having the composition of (ac) achieves total wetting. and the composition in (d) shows a contact angle of 12°, (e) a time series image showing the wetting state for a solution of 7.0 w/w% PEGDA, 3.0 w/w% water and 90.0 w/w% ethanol, ethanol is It is an image confirming that it is completely depleted at 42 seconds and there is no transition from full wetting to partial wetting.
Figure 7 is (a) a schematic diagram showing the formation of an ultra-thin hydrogel skin, (b, c) SEM images of a hierarchical nanostructure encapsulated with an ultra-thin hydrogel skin taken at two different magnifications, (d) thick protective platinum SEM image showing the cross-section of the nanostructure prepared by trimming the structure with a focused ion beam after depositing the layer, (e) a transmission electron microscopy (TEM) image showing the thickness of the hydrogel skin as shown, (f) hydrogel Fluorescein isothiocyanate (MWs) with three different molecular weights (MWs) of 10, 20 and 40 kDa measured in gel-free bare nanostructures (black line) and ultra-thin hydrogel encapsulated nanostructures (blue line). FITC) Characteristic peak positions of FITC as the Raman spectral contour of the tagged dextran are indicated by the red dotted line, (g) Ultra-thin hydrogel skin normalized to bare nanostructures without hydrogels for three different MWs of dextran molecules The Raman intensity at 1176 cm ⁻¹ measured in nanostructures encapsulated with
Figure 8 (a, b) is a photograph of a bulk hydrogel film in air (dry state, a) and water (wet state, b), wherein the film is 69.6 w/w% PEGDA and 29.9 w/w% water and 0.5 w Prepared using a mixture of /w% photoinitiators and immersed in distilled water for 10 h for wet state, the lateral dimensions of the square film were 2.0 cm in dry state and increased to 2.4 cm in wet state, (c) decorated with Ag NPs. A simplified model of the cross-section of an ultra-thin hydrogel encapsulated Au-Ag NW with dimensions shown in the image in nm, the initial volume fraction of Ag NPs embedded in the cylindrical hydrogel skin is 20%, and the hydrogel skin volume is 173 Assuming % swelling, the average thickness of wet hydrogel skin is estimated to be about 32 nm.
9 is a SEM image of a thick hydrogel encapsulated nanostructure, in which the hydrogel occupies the entire interstitial space between the NWs and covers the nanostructure.
10 is a schematic diagram of (a) a bare nanostructure without hydrogel, (b) an ultra-thin hydrogel encapsulated nanostructure, and (c) a plasmonic nanostructure that is a thick hydrogel encapsulated nanostructure, each dissolved in distilled water at various concentrations. It shows the Raman spectrum of tricyclazole, (d) showing the Raman intensity at 1365 cm ^-1 as a function of tricyclazole concentration for three different nanostructures in (ac), where the concentration is on a logarithmic scale , error bars represent standard deviation for 5 measurements.
11 shows (a) a photograph of a SERS substrate dipped in milk (left photograph) and an ultra-thin access to tricyclazole on the metal surface for Raman measurements while rejecting the large proteins of albumin and casein (middle and right photograph). It shows the schematic diagram of the hydrogel encapsulation nanostructure, (b) shows the Raman spectrum of tricyclazole immobilized in milk at various concentrations measured in the ultra-thin hydrogel encapsulation nanostructure, and (c) Raman at 1365 cm ^-1 Intensity is a function of tricyclazole concentration for ultra-thin hydrogel encapsulated nanostructures (red dots) with concentrations logarithmic scale (red dots) and bare nanostructures without hydrogel (black squares), error bars are 5 measurements. represents the standard deviation for .
12 is a Raman spectrum obtained from a nanostructure without hydrogel immersed in distilled water (black line), an ultra-thin hydrogel encapsulated nanostructure immersed in distilled water (red line), and an ultra-thin hydrogel encapsulated nanostructure immersed in milk (blue line). The vertical dotted line shows the common peaks of the three spectra from poly(vinylpyrrolidone) (PVP), the capping agent for Ag NWs.
13 shows Raman spectra of tricyclazole immobilized in milk at various concentrations measured in bare nanostructures without hydrogel.
Figure 14 shows the Raman intensity at 1365 cm ^-1 as a function of incubation time of bare nanostructures without hydrogel (black squares) and ultra-thin hydrogel encapsulated nanostructures (red dots) in milk containing 1 ppm tricyclazole. As shown, the Raman spectrum was obtained after complete drying, and the error bars represent the standard deviation for 5 measurements.
15 is a Raman spectrum measured using a nanostructure encapsulated in an ultra-thin hydrogel, tricyclazole (blue curve), paraquat (red curve), and a mixture of tricyclazole and paraquat (black curve), respectively. It is fixed at a concentration of 1 ppm in milk, and the blue and red dotted lines indicate the characteristic peak positions of tricyclazole and paraquat, respectively.

In one aspect of the invention

a metal nanowire made of a first metal; and metal nanoparticles made of a second metal formed on the surface of the metal nanowire; and

A plasmonic composite structure comprising a; hydrogel skin surrounding the nanostructure is provided.

Hereinafter, the plasmonic composite structure provided in one aspect of the present invention will be described in detail.

The plasmonic composite structure of the present invention includes a plasmonic nanostructure for surface-enhanced scattering coated with an ultra-thin hydrogel skin. This may be a plasmonic nanostructure encapsulated in a hydrogel skin. By selectively permeating only the target material, the pre-treatment process of the sample can be eliminated, and the metal particles inside can be prevented from being contaminated. The plasmonic nanostructure for surface-enhanced scattering coated with the ultra-thin hydrogel skin of the present invention can be manufactured as a product in the form of a chip, and even beginners can simply measure it without additional equipment in the field. In addition, the ultra-thin hydrogel coating technology of the present invention can be coated on various metal surfaces, and can be easily manufactured and mass-produced through a simple solution process.

In the plasmonic composite structure provided in one aspect of the present invention, the plasmonic nanostructure includes a metal nanowire made of a first metal; and metal nanoparticles made of a second metal formed on the surface of the metal nanowire. The nanostructure may be one in which metal nanoparticles are formed on at least a portion of the surface of the metal nanowire. For example, the metal nanoparticles may be formed on the surface of the nanowire while surrounding all of the outer peripheral surface of the metal nanowire, or may be formed on only one surface of the metal nanowire.

The first metal and the second metal are silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) and and at least one selected from the group consisting of manganese (Mn), wherein the first metal and the second metal may be the same as or different from each other. For example, the first metal may be silver nanowires, and the second metal may be silver nanoparticles.

The metal nanowire may have a diameter of 10 nm to 500 nm, 15 nm to 450 nm, 20 nm to 400 nm, 25 nm to 350 nm, and 30 nm to 300 nm. and may be 35 nm to 250 nm, may be 20 nm to 200 nm, may be 20 nm to 100 nm, may be 30 nm to 50 nm, may be 10 nm to 100 nm, may be 10 nm to It may be 80 nm, it may be 15 nm to 50 nm, and it may be 10 nm to 60 nm. The diameter may be an average diameter.

The diameter of the metal nanoparticles may be 5 nm to 200 nm, may be 10 nm to 150 nm, may be 15 nm to 100 nm, may be 20 nm to 80 nm, may be 25 nm to 60 nm It may be 30 nm to 60 nm, may be 5 nm to 100 nm, may be 10 nm to 80 nm, may be 15 nm to 60 nm, may be 20 nm to 100 nm, may be 25 nm to It may be 100 nm, may be 20 nm to 80 nm, may be 20 nm to 60 nm, may be 30 nm to 100 nm, may be 30 nm to 80 nm. The diameter may be an average diameter.

The nanostructure may further include a metal coating layer made of a third metal formed between the metal nanowires and the metal nanoparticles. The metal coating layer may be formed on the surface of the metal nanowire.

The third metal is silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) and manganese (Mn). It may be at least one selected from the group consisting of, for example, may be gold, and may form a gold coating layer.

The thickness of the metal coating layer may be 5 nm to 50 nm, 5 nm to 45 nm, 5 nm to 40 nm, 5 nm to 35 nm, 5 nm to 30 nm, and , 5 nm to 25 nm, 5 nm to 15 nm, 10 nm to 50 nm, 10 nm to 45 nm, 10 nm to 40 nm, 10 nm to 35 nm may be nm, may be 10 nm to 30 nm, may be 10 nm to 25 nm, may be 10 nm to 20 nm, may be 10 nm to 15 nm, may be 15 nm to 50 nm, 15 nm to 45 nm, 15 nm to 40 nm, 15 nm to 35 nm, 15 nm to 30 nm, 15 nm to 25 nm, 15 nm to 20 nm can be

The nanostructure may include a metal coating layer formed on the surface of the metal nanowire, and a self-assembled monolayer (SAM) formed on the surface of the metal coating layer. The metal nanoparticles are formed on the metal nanowire through the self-assembled monolayer, and may be attached through the self-assembled monolayer. A low surface energy can be exhibited through a self-assembled monolayer. In addition, the self-assembled monolayer film may be removed except for a portion connected to the metal nanoparticles in order to open the surface of the metal coating layer.

The self-assembled monolayer may include perfluorodecanethiol (PFDT).

The thickness of the self-assembled monolayer film may be 0.5 nm to 100 nm, may be 1 nm to 50 nm, may be 2 nm to 35 nm, may be 3 nm to 30 nm, and may be 5 nm to 20 nm. have.

In the plasmonic composite structure provided in one aspect of the present invention, the composite structure is in the form of a nanostructure coated with a hydrogel skin. The nanostructure may be individually coated with a hydrogel skin, and the hydrogel skin may be surrounded by a plasmonic nanostructure. It is preferable that the form is wrapped with an ultra-thin hydrogel skin rather than a bulk-type hydrogel film.

The hydrogel skin is polyethylene glycol diacrylate (Polyethylene (glycol) Diacrylate), polyethylene glycol methyl ether acrylate, polyacrylamide (Polyacrylamide), poly (N- isopropyl acrylamide) (Poly (N-isopropylacrylamide)) and It may be formed of one or more polymers selected from the group consisting of hydroxyethyl methacrylate.

The hydrogel skin coats the plasmonic nanostructure, rejects molecules larger than a predetermined mesh size, and has a limited structure that allows injection of smaller molecules. The mesh size may be 1 nm to 10 nm, 2 nm to 8 nm, 3 nm to 7 nm, 4 nm to 6 nm, and 5 nm to 6 nm.

The hydrogel skin may have a structure that surrounds the surface to such an extent that the metal nanoparticles of the nanostructure are not exposed and wraps along the surface of the metal nanoparticles.

The thickness of the hydrogel skin may be 1 nm to 100 nm, 5 nm to 80 nm, 10 nm to 60 nm, 12 nm to 40 nm, 15 nm to 30 nm and may be 20 nm to 25 nm, may be 5 nm to 60 nm, may be 5 nm to 40 nm, may be 5 nm to 30 nm, may be 5 nm to 25 nm, may be 10 nm to It may be 40 nm, it may be 10 nm to 30 nm, it may be 10 nm to 25 nm, it may be 15 nm to 40 nm, it may be 15 nm to 25 nm, it may be 20 nm to 22 nm. .

In the present invention, by using surface-enhanced Raman scattering, an ultra-thin hydrogel skin showing selective permeability with respect to size was formed on the surface of a plasmonic nanostructure for the detection of toxic molecules in a complex mixture without pretreatment, and thus major toxic molecules in the mixture were formed. Block access to plasmonic nanostructures through size-selective penetration of ultra-thin hydrogels for large-sized substances that interfere with detection can do. As such, by coating an ultra-thin hydrogel skin having selective molecular size selective permeation on the surface of a plasmonic nanostructure for surface-enhanced scattering, it selectively transmits only a small target material to simplify or exclude the pretreatment process of the mixture sample. , it can be usefully used to detect specific toxic substances contained in mixtures.

In addition, in another aspect of the present invention

forming a metal coating layer made of a third metal on the surface of the metal nanowire made of the first metal;

forming a self-assembled monolayer (SAM) on the metal coating layer;

forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and

Forming a hydrogel skin surrounding the nanostructure in the nanostructure; is provided a method of manufacturing a plasmonic composite structure comprising a.

Hereinafter, each step will be described in detail with respect to the manufacturing method of the plasmonic composite structure provided in another aspect of the present invention.

First, the method of manufacturing a plasmonic composite structure provided in another aspect of the present invention includes forming a metal coating layer made of a third metal on the surface of a metal nanowire made of a first metal.

As shown in Figure 1 (a), in this step, a metal coating layer is formed on the surface of the metal nanowire to prepare a plasmonic composite structure.

The first metal includes silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) and manganese (Mn). It may include one or more selected from the group consisting of. For example, the first metal may be silver and may be silver nanowires.

The metal nanowire may have a diameter of 10 nm to 500 nm, 15 nm to 450 nm, 20 nm to 400 nm, 25 nm to 350 nm, and 30 nm to 300 nm. and may be 35 nm to 250 nm, may be 20 nm to 200 nm, may be 20 nm to 100 nm, may be 30 nm to 50 nm, may be 10 nm to 100 nm, may be 10 nm to It may be 80 nm, it may be 15 nm to 50 nm, and it may be 10 nm to 60 nm. The diameter may be an average diameter.

The third metal is silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) and manganese (Mn). It may be at least one selected from the group consisting of, for example, may be gold, and may form a gold coating layer.

The thickness of the metal coating layer may be 5 nm to 50 nm, 5 nm to 45 nm, 5 nm to 40 nm, 5 nm to 35 nm, 5 nm to 30 nm, and , 5 nm to 25 nm, 5 nm to 15 nm, 10 nm to 50 nm, 10 nm to 45 nm, 10 nm to 40 nm, 10 nm to 35 nm may be nm, may be 10 nm to 30 nm, may be 10 nm to 25 nm, may be 10 nm to 20 nm, may be 10 nm to 15 nm, may be 15 nm to 50 nm, 15 nm to 45 nm, 15 nm to 40 nm, 15 nm to 35 nm, 15 nm to 30 nm, 15 nm to 25 nm, 15 nm to 20 nm can be

The metal coating layer may be formed by a sputtering method.

Next, the method of manufacturing a plasmonic composite structure provided in another aspect of the present invention includes forming a self-assembled monolayer (SAM) on the metal coating layer.

In the above step, to coat the surface of the metal coating layer with a hydrophobic molecular layer, a self-assembled monolayer film is formed on the metal coating layer formed on the surface of the metal nanowire.

The self-assembled monolayer may include perfluorodecanethiol (PFDT). The forming of the self-assembled monolayer may be performed by applying a solution containing perfluorodecanethiol and culturing.

The thickness of the self-assembled monolayer film may be 0.5 nm to 100 nm, may be 1 nm to 50 nm, may be 2 nm to 35 nm, may be 3 nm to 30 nm, and may be 5 nm to 20 nm. have.

Next, the method for manufacturing a plasmonic composite structure provided in another aspect of the present invention includes the step of forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer.

In the above step, a plasmonic nanostructure is formed by forming metal nanoparticles made of a second metal on a self-assembled monolayer, which is a hydrophobic molecular layer.

The second metal is silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr), and manganese (Mn), respectively. It may include one or more selected from the group consisting of. For example, the second metal may be silver to form silver nanoparticles.

The diameter of the metal nanoparticles may be 5 nm to 200 nm, may be 10 nm to 150 nm, may be 15 nm to 100 nm, may be 20 nm to 80 nm, may be 25 nm to 60 nm It may be 30 nm to 60 nm, may be 5 nm to 100 nm, may be 10 nm to 80 nm, may be 15 nm to 60 nm, may be 20 nm to 100 nm, may be 25 nm to It may be 100 nm, may be 20 nm to 80 nm, may be 20 nm to 60 nm, may be 30 nm to 100 nm, may be 30 nm to 80 nm. The diameter may be an average diameter.

Forming the metal nanoparticles may be performed through a method of thermal evaporation of the metal.

The second metal is deposited using a thermal evaporation method to form nanoparticles, and thereafter, the self-assembled monolayer may be partially removed. Part of the self-assembled monolayer may be removed by plasma treatment.

Next, the method of manufacturing a plasmonic composite structure provided in another aspect of the present invention includes forming a hydrogel skin surrounding the nanostructure in the nanostructure.

In the above step, the surface of the plasmonic nanostructure prepared in the previous step is wrapped with a hydrogel skin, and each of the nanostructures is individually formed in a form coated with a hydrogel skin.

The hydrogel skin is polyethylene glycol diacrylate (Polyethylene (glycol) Diacrylate), polyethylene glycol methyl ether acrylate, polyacrylamide (Polyacrylamide), poly (N- isopropyl acrylamide) (Poly (N-isopropylacrylamide)) and It may be formed of one or more polymers selected from the group consisting of hydroxyethyl methacrylate.

The hydrogel skin coats the plasmonic nanostructure, rejects molecules larger than a predetermined mesh size, and has a limited structure that allows injection of smaller molecules. The mesh size may be 1 nm to 10 nm, 2 nm to 8 nm, 3 nm to 7 nm, 4 nm to 6 nm, and 5 nm to 6 nm.

The thickness of the hydrogel skin may be 1 nm to 100 nm, 5 nm to 80 nm, 10 nm to 60 nm, 12 nm to 40 nm, 15 nm to 30 nm and may be 20 nm to 25 nm, may be 5 nm to 60 nm, may be 5 nm to 40 nm, may be 5 nm to 30 nm, may be 5 nm to 25 nm, may be 10 nm to It may be 40 nm, it may be 10 nm to 30 nm, it may be 10 nm to 25 nm, it may be 15 nm to 40 nm, it may be 15 nm to 25 nm, it may be 20 nm to 22 nm. .

Forming the hydrogel skin may be performed using a composition for forming a hydrogel skin including a polymer such as polyethylene glycol diacrylate, water, and a photoinitiator, and a plasmonic nanostructure is supported in the composition to emit light. It can be done by investigation.

The concentration of the polymer in the composition for forming a hydrogel skin may be from 0.1 w/w% to 5 w/w%, from 0.5 w/w% to 4 w/w%, from 0.8 w/w% to 3 w /w%, may be 1 w/w% to 2 w/w%, may be 1.2 w/w% to 1.6 w/w%. At the same time the concentration of water may be 0.1 w/w% to 1.0 w/w%, 0.2 w/w% to 0.9 w/w%, 0.3 w/w% to 0.8 w/w%, 0.4 It may be w/w% to 0.7 w/w%, and may be 0.5 w/w% to 0.6 w/w%.

The composition for forming a hydrogel skin may further include an organic solvent, and the organic solvent may be alcohols, and ethanol may be used as an example.

Furthermore, in another aspect of the present invention

Board; and

There is provided a substrate for surface-enhanced Raman spectroscopy for detecting a target material, including the plasmonic complex structure formed on the substrate.

Since the plasmonic complex structure is the same as described above, a detailed description thereof will be omitted below.

The substrate may have a micro-well array structure to pixelate the plasmonic nanostructures into separate compartments. For example, the substrate is made of polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), silicon (Si), glass and quartz. It may include a first layer including at least one material selected from the group consisting of, and a second layer forming a micro-well array structure. As a specific example, the substrate may be one in which a metal layer of a predetermined thickness is formed on a PEN substrate, and a micro-well array structure is formed on the metal layer through a polymer of a predetermined pattern. The predetermined pattern may be a checkerboard line pattern.

In addition, the plasmonic complex structure may be a 3D structure in which multiple stacks are formed. The nanostructure or metal nanowire constituting the plasmonic composite structure may be a stacked structure to form a stack. The thickness of the multi-stack may be 20 nm to 100 nm, may be 20 nm to 50 nm, may be 20 nm to 40 nm, may be 20 nm to 30 nm, may be 30 nm to 40 nm .

Furthermore, in another aspect of the present invention

preparing a substrate;

forming a metal nanowire made of a first metal on the substrate;

forming a metal coating layer made of a third metal on the surface of the metal nanowire;

forming a self-assembled monolayer (SAM) on the metal coating layer;

forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and

There is provided a method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material, including the step of forming a hydrogel skin surrounding the nanostructure on the nanostructure.

Hereinafter, a method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material provided in another aspect of the present invention will be described in detail for each step.

First, the method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material provided in another aspect of the present invention includes preparing the substrate.

In the above step, a substrate is prepared to prepare a substrate for surface-enhanced Raman spectroscopy for detecting a target material.

The substrate may have a micro-well array structure to pixelate the plasmonic nanostructures into separate compartments. For example, the substrate is made of polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), silicon (Si), glass and quartz. It may include a first layer including at least one material selected from the group consisting of, and a second layer forming a micro-well array structure. The substrate may be one in which a metal layer of a predetermined thickness is formed on a PEN substrate, and a microwell array structure is formed on the metal layer through a polymer having a predetermined pattern. The predetermined pattern may be a checkerboard line pattern.

As a specific example, first, a substrate such as a polymer substrate or a silicon substrate may be prepared, and a metal thin film may be formed on the substrate. In this case, an adhesive layer such as Cr may be formed in order to introduce a strong adhesive force to the substrate. Thereafter, a metal layer having a predetermined thickness may be formed. The metal layer may include silver and may have a thickness of 50 nm to 500 nm, 60 nm to 400 nm, 70 nm to 300 nm, 80 nm to 200 nm, and 90 nm to 150 nm. Thereafter, a pattern for forming a micro-well array structure may be formed with a photopolymer on the metal layer. The pattern may be a checkerboard line pattern.

Next, a method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material provided in another aspect of the present invention includes forming a metal nanowire made of a first metal on the substrate.

In this step, metal nanowires are formed on the substrate prepared in the previous step.

The formation of the metal nanowires may be performed so that multiple stacks of a 3D structure are formed. A stack can be formed by stacking metal nanowires. The thickness of the multi-stack may be 20 nm to 100 nm, may be 20 nm to 50 nm, may be 20 nm to 40 nm, may be 20 nm to 30 nm, may be 30 nm to 40 nm .

Next, a method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material provided in another aspect of the present invention comprises: forming a metal coating layer made of a third metal on the surface of the metal nanowire; forming a self-assembled monolayer (SAM) on the metal coating layer; forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and forming a hydrogel skin surrounding the nanostructure in the nanostructure.

Since the above step can be performed in the same manner as the step performed in the above-described method for manufacturing the plasmonic composite structure, a detailed description thereof will be omitted.

In addition, in another aspect of the present invention

A method for detecting a target material using the substrate for surface-enhanced Raman spectroscopy for detecting the target material is provided.

For example, it may be carried out by supporting a substrate for surface-enhanced Raman spectroscopy in a composition containing the target material.

In the present invention, an ultra-thin hydrogel skin having selective molecular size selective permeation is coated on the surface of a complex plasmonic nanostructure for surface-enhanced scattering to selectively transmit only a small target material, thereby simplifying or excluding the pretreatment process of the mixture sample. Therefore, it can be usefully used to detect a specific toxic substance contained in a mixture. For example, it can be used for disease diagnosis through the evaluation of disease biomarkers in biological samples (blood, urination, saliva, sweat), and can be used for food safety evaluation through the evaluation of toxic substances in food (dairy products, eggs, beverages). . Since covalent chemical bonding of the sample is not required, it can be used in the bio field, such as cell-based analysis of living cells. In addition, by coating the hydrogel skin on the surface of various structures as well as the surface of the material for surface-enhanced scattering, it is possible to impart molecular size-selective permeation ability. For example, it is possible to coat the hydrogel skin on the surface of electrochemical sensors and semiconductor sensors, which are commercialized and widely used in the sensor part, and can be widely used in industry, agriculture, and the environment.

In Raman spectroscopy technology, since each molecule has its own Raman signal, multiple detection is possible at the same time, which is also an important advantage. Because the effect is disturbed, the Raman signal of the target material to be detected is reduced or noise of the Raman signal of the target molecule is generated, so that it is difficult to accurately detect a low concentration. Bulk hydrogels are thicker than micro-size and are affected by the diffusion rate of molecules in the fluid, so it is difficult to quickly detect the target material in the field. Accordingly, in the present invention, by coating a nanometer-level ultra-thin hydrogel skin on the surface of the plasmonic nanostructure, it enables faster and more accurate Raman analysis by selectively penetrating target molecules. In addition, it is easy to manufacture, can be mass-produced, has bio-stability, and high-speed detection is possible. It is also a great advantage that the coating technology used in the present invention can be applied to various sensor fields.

Hereinafter, the present invention will be described in detail through Examples and Experimental Examples.

However, the following examples and experimental examples are only for illustrating the present invention, and the content of the present invention is not limited by the following examples and experimental examples.

<Example>

After removing the protective film, a PEN substrate (Q65HA, Teonex, Inc) having a thickness of 180 μm was used. A 100 nm thick Ag layer was directly deposited on a flat PEN substrate at a deposition rate of 1.8 A/s using a thermal evaporation system (LAT, Korea). At this time, a 10 nm thick Cr layer was deposited to ensure strong adhesion between the Ag layer and the PEN substrate. The base pressure of the chamber is 9.6 × 10 ^-6 Torr.

The photopolymer (NOA 63, Norland Products, Inc.) was deposited in a checkerboard line pattern using a dispenser machine (Musashi, Shotmini 200S) equipped with a 10 mL glass syringe. A checkerboard line pattern was drawn at intervals of 3.5 mm with a metal needle with an outer diameter of 0.82 mm and an inner diameter of 0.52 mm connected to a glass syringe. Then, the checkerboard line pattern was exposed to UV light emitted from an Hg arc lamp for 60 seconds to prepare a substrate having a micro-well array structure.

An aqueous suspension of 0.3 wt% Ag nanowires (Ag NW, Nanophyxis Co., Ltd.) having an average diameter of 40 nm was dropped on the substrate to form multiple stacked Ag NWs. The number of stacks or stacks can be determined with suspension volumes ranging from 2 μl to 10 μl. Here, it was decided to deposit 6 μl of Ag NW suspension into each microwell of the substrate, and dried water.

A 15 nm-thick Au layer was formed on the surface of the 3D stack of Ag NWs by sputtering.

Then, a self-assembled monolayer (SAM), which is perfluorodecanethiol (PFDT), was coated on the Au layer by vapor-phase deposition. In particular, micro-well arrays containing multi-stack Au-coated Ag NWs (Au-Ag NWs) were incubated for 2 hours in a closed glass Petri dish containing 20 μl of a 97% PFDT solution.

Thereafter, using thermal evaporation, Ag nanoparticles (Ag NPs) were deposited on PFDT-coated Au-Ag NWs at a deposition rate of 0.3 A/s to prepare a plasmonic nanostructure.

1 μl ethanol solution of 1.4 w/w% PEGDA (MW 700 g/mol, Sigma-Aldrich), 0.6 w/w% water and 0.01 w/w% photoinitiator 1- [4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959, BASF) was added dropwise to each microwell and ethanol was evaporated for 5 min. did it The micro-well was irradiated with UV light for 15 seconds, and finally a plasmonic composite structure was prepared.

At this time, for encapsulation through a thick bulk hydrogel, the same protocol was performed using 1 μl of an aqueous solution of 7 w/w% PEGDA, 3 w/w% water and 0.05 w/w% photoinitiator.

<Experimental example>

- Characterization and SERS measurement

The surface morphology was analyzed by field emission scanning electron microscopy (FE-SEM; Jeol JSM-6700F). SERS spectra of methylene blue (MB) were recorded using a handheld Raman spectrometer (CBEx, Snowy Range Instruments) equipped with 633 and 785 nm lasers. The laser power is 10 mW. The SERS signal of tricyclazole was measured using a handheld Raman spectrometer (NS220, Nanoscope Systems Inc., Daejeon, South Korea) with a laser wavelength of 633 nm, a laser power of 0.5 mW, and an exposure time of 5 sec.

- Numerical simulations

A finite-difference time-domain simulation (FDTD) was performed with the FDTD solution software (version 8.21, Lumerical Solutions). The nanostructures were built based on SEM observations using Autodesk Fusion 360 and then exported as an FDTD solution. A linearly polarized plane wave with an excitation wavelength of 633 nm was directly incident on the plasmonic nanostructure polarized in the Au-Ag NW direction from the Ag NP. In the simulation, the dielectric constants of Au and Ag were set to ε _Au = -8.962364 + 1.164 i and ε _Ag = -15.037239 + 1.162 i at 633 nm. The refractive index of the PFDT was set to 1.333.

<Experimental results and analysis>

A hierarchical nanostructure composed of 3D multi-stacks of silver nanowires (Ag NWs) decorated with high-density silver nanoparticles (Ag NPs) and coated with a 10 nm-thick Au layer as a plasmonic composite structure with high SERS activity. use These plasmonic nanostructures were prepared in five steps. 1) Ag NWs are stacked in multiple layers, 2) Au layer is coated by sputtering on the Ag NW surface, 3) the surface of the Au layer is coated with a self-assembled monolayer film, which is a hydrophobic molecular layer, 4) Ag is deposited through thermal evaporation Deposition, 5) The exposed hydrophobic molecular layer was etched by Ar-plasma treatment as shown in Fig. 1(a). In order to pixelate the plasmonic nanostructures into separate compartments, as shown in FIG. 2 , a 6 × 6 square micro-well array was fabricated and used. Microwell arrays were prepared by drawing checkerboard line patterns using photocurable resin with a highly accurate dispensing system. A 100 nm thick Ag layer was deposited on a flat polyethylene naphthalate (PEN) substrate by thermal evaporation, which was used as a substrate for the preparation of micro-well arrays. The Ag layer can minimize light transmission during Raman measurements. The lateral dimension of each microwell is 3.5 mm and the height is 0.8 mm.

To deposit Ag NWs in each microwell, a controlled volume of a 0.3 w/w% aqueous suspension of Ag NWs with an average diameter of 40 nm is deposited through a dispenser and the water is evaporated completely. For the deposition of 2 μl aqueous suspension Ag NWs formed a low density stack of 2 or 3 layers, as shown in Fig. 3(a). As the volume increases, the number of layers and the volume ratio increase. For example, deposition of 6 μl aqueous suspension formed 5 or 6 high-density stacks. In order to find the optimal thickness of a multi-stack for Raman analysis, 2 μl of a 5 μM methylene blue (MB) aqueous solution was dropped into a microwell and evaporated, and then, as shown in FIGS. 3(b) to 3(d), portable Raman Raman spectra were obtained using a spectrometer. Excitation lasers with wavelengths of 633 nm and 785 nm were used, respectively. As the number of layers increased for excitation of two wavelengths, it was confirmed that the Raman intensity increased with the volume of the aqueous suspension from 2 μl to 4 μl. However, when the volume is further increased to 8 μl, the strength is rather decreased. The decrease in intensity is due to the decrease in the surface concentration of MBs due to the larger surface area of the thicker stacks, whereas the penetration depth of the excitation beam is limited to several stacks. As shown in Figure 1(b), 6 μl of suspension can be selected to form multiple stacks in a micro-well array.

To enhance the SERS activity, the surface of Ag NWs is decorated with Ag NPs highly enriched in nanogaps. To produce Ag NPs, Ag NWs were first coated with a 10 nm thick Au layer by sputtering, and then covered with a self-assembled monolayer (SAM) of perfluorodecanethiol (PFDT) using vapor deposition. Self-assembled monolayers render surfaces with low surface energy. The PFDT layer has a surface energy of γ _PFDT = 0.015 J/m ² . When Ag is deposited through thermal evaporation, individually isolated Ag NPs are formed on the surface of the PFDT-coated Au-Ag NWs rather than as a soft film, as shown in Fig. 1(c). Due to the low surface energy of the PFDT layer and the high energy of Ag (γ _Ag = 1.20 J/m ² ), Ag atoms diffuse along the PFDT surface until they form spherical Ag NPs during deposition. Finally, the PFDT layer is etched by Ar-plasma treatment to make the Au layer surface derived and the resulting hierarchical nanostructure is used for molecular detection via SERS. The reflectance spectrum was measured at each manufacturing step as shown in FIG. 4 . The reflectance at 633 nm was 30% for 3D multiple stacks of Ag NWs, and decreased to 10% for Au layer deposition to form Au-Ag NWs. The additional treatment of decorating Au-Ag NWs with Ag NPs with PFDT coating and Ag deposition slightly changed the reflectance depending on the deposition conditions of Ag.

As shown in Fig. 5, the diameter of Ag NPs is relatively large at the upper surface of Au-Ag NWs and small at the side due to the directional flux of Ag during deposition. Also, there are no Ag NPs on the bottom surface. Using the deposition conditions to form a 20 nm-thick layer on a flat surface, the diameter of the Ag NPs on the top surface is about 60 nm, the diameter on the side surface is about 30 nm, and the average diameter is 34.4 nm. This can be confirmed through FIG. 5 . Based on these observations, the 3D architecture near the intersection of Ag NWs can be reconstructed through finite differential time domain (FDTD) simulation as shown in Fig. 1(e). For plane wave radiation with a wavelength of 633 nm, the electric field is locally enhanced from Ag NPs to Au-Ag NW nanogaps and from Ag NPs to Ag NP nanogaps as a result of the LSPR coupling effect, providing multiple hotspots. Ag NPs formed on the side of the Au-Ag NW can maximize near-field reinforcement because the nanogap is aligned parallel to the polarization direction of the incident light. The surface morphology can be further altered by adjusting the deposition conditions. With deposition conditions for 30 nm thick and 40 nm thick layers, respectively, the average diameters of Ag NPs are 49 nm and 61 nm, and the number of Ag NPs decreases when depositing thick layers (see Fig. 5).

The Raman signal of methylene blue (MB) is greatly improved by forming Ag NPs on the surface of Ag NWs as shown in Fig. 1(f). The Raman shift intensity of 433 cm ⁻¹ increased by 10.5 times under the deposition condition of a 20 nm thick layer compared with the stack without Ag NPs of Ag NWs, and 9.9 times and 5.6 times under the condition of 30 nm thick and 40 nm thick layers, respectively. increased. This trend is consistent with a decrease in reflectance or an increase in absorbance at 633 nm with Ag deposition thickness (see Fig. 4). The decrease in Raman intensity and increase in reflectance for thick Ag deposition is attributed to the growth of Ag NPs by fusion reducing the number of nanogaps.

Because metal surfaces are prone to contamination due to irreversible and nonspecific adsorption of proteins, it is difficult to use metal nanostructures to directly detect small molecules in biological fluids via SERS. Encapsulated in hydrogel skins as hierarchical nanostructures optimized to exclude adhesion proteins while allowing access of small target molecules to the metal surface. Hydrogels are water-swelled 3D polymer networks composed of hydrophilic groups, which can inject small molecules and reject larger molecules than limit the mesh size of the network. This size-selective permeation allows the direct detection of small molecules in complex biological fluids without tedious sample preparation. However, diffusion of molecules through the hydrogel network is significantly delayed, preventing rapid molecular detection. Therefore, it is preferable to coat the metal surface with a thin hydrogel skin rather than forming a bulk hydrogel matrix to minimize the diffusion length. A highly diluted ethanol solution of the hydrogel precursor of PEGDA was used to form a thin ultra-thin hydrogel skin on the surface of individual Ag NWs. In each microwell, 1 μl ethanol solution of 1.4 w/w% PEGDA, 0.6 w/w% water and 0.01 w/w% photoinitiator was dropped to evaporate the ethanol. As the solution spreads on the Ag surface in the total wetting regime (see Fig. 6), evaporation of ethanol creates a thin layer of PEGDA-rich solution on the entire surface of the nanostructures and emptys the interstitial voids between the Ag NWs. . Although the transition from full wetting to partial wetting occurs when the fraction of ethanol at equilibrium falls below 50%, dewetting is not possible even in complete drying of ethanol because thin films of viscous liquids exhibit very slow dewetting kinetics. was not observed (see FIG. 6). PEGDA is polymerized by irradiating the nanostructure with ultraviolet (UV) light for 15 seconds. The procedure is summarized in Fig. 7(a).

Total wetting completely encapsulates the entire surface of the hierarchical nanostructure with an ultra-thin hydrogel skin while maintaining large interstitial voids between Ag NWs, as shown in Figs. 7(b) and 7(c). The metal surface is not directly exposed to the surroundings. The thickness of the hydrogel skin causes surface waves according to the arrangement of Ag NPs on the surface of Au-Ag NWs. This structural feature means that the thickness of the hydrogel skin is similar to or smaller than the diameter of Ag NPs. To further investigate the structural features, as shown in Fig. 7(d), a thick platinum layer was deposited and then the multiple stacks were trimmed with a focused ion beam. Although the structure is partially distorted during trimming, it is clearly shown that the Ag NWs in the top layer are decorated with Ag NPs. The Ag NWs in the bottom layer are not decorated with Ag NPs as expected from the Ag deposition geometry. In addition, Ag NPs and Ag NWs are surrounded by an ultra-thin hydrogel skin. The fracture of the metal-hydrogel composite structure is also observed with a transmission electron microscope (TEM), which confirms the hydrogel skin with a thickness of about 21 nm in the dried state as shown in FIG. 7(e). As shown in FIG. 8 , the bulk hydrogel film having the same composition as the hydrogel skin shows a volume expansion ratio of 173%. Assuming that the hydrogel skin has the same swelling ratio, the thickness in the wet state is estimated to be about 32 nm in the simplified model structure as shown in Fig. 8(c).

The size-selective permeability of ultrathin hydrogel skins was demonstrated using a set of dextran molecules tagged with fluorescein isothiocyanate (FITC) with three molecular weights (MWs). As shown in FIG. 7(f), when an aqueous solution of FITC-tag dextran having a molecular weight (MW) of 10 kDa is dropped, both the hydrogel encapsulated nanostructure and the hydrogel-free bare nanostructure 1176, 1313, 1535 and 1589 The Raman spectrum of FITC with a strong characteristic peak at cm ⁻¹ is shown. This indicates that the mesh size limited by the hydrogel skin is larger than the hydrodynamic diameter of the FITC-tagged dextran with a MW of 10 kDa, 4.6 nm. It is worth noting that the intensity of the Raman signal measured in the hydrogel-encapsulated nanostructure is as high as about 70% of the intensity measured in the bare nanostructure without the hydrogel, even through the entire surface coated with the hydrogel. In the case of FITC-tagged dextran with a MW of 20 kDa, only the Raman spectrum measured from a basic nanostructure without a hydrogel shows a sharp and strong characteristic peak of FITC. The signal intensity of the Raman spectrum at 1176 cm ^-1 measured in the hydrogel encapsulated nanostructure is only 10% of the signal intensity of the bare nanostructure without the hydrogel. Using FITC-tagged dextran with a MW of 40 kDa reduces the relative intensity to 7%. The relative intensities at 1176 cm ⁻¹ for FITC-tagged dextran with MWs of 10, 20 and 40 kDa are shown in FIG. 7( g ). A sharp change in relative intensity is observed as the MW increases from 10 kDa to 20 kDa, indicating that the cutoff threshold of permeation is between 4.6 nm and 6.6 nm, indicating that the MW is 10 kDa and 20 kDa, respectively. It is the hydrodynamic diameter of dextran.

Rapid in situ detection of toxic molecules is very important and strongly required in the food industry. The targeted molecule, tricyclazole, is widely used as a fungicide to prevent rice blasts in grains, vegetables and fruits, and accumulates in the milk of cows at the top of the food chain. Therefore, the European Union (EU) has set the maximum residual limit (MRL) of tricyclazole in milk at a very low level (eg 10 ppb). First, the detection sensitivity of tricyclazole dissolved in distilled water was evaluated using a hydrogel-free nanostructure and an ultra-thin hydrogel encapsulated nanostructure. In addition, as shown in FIG. 9 , a hierarchical nanostructure in which all pores were filled with a hydrogel matrix was prepared in order to study the effect of the thinness of the hydrogel skin. The thick hydrogel matrix was prepared by dropping 1 μl ethanol solution of 7 w/w% PEGDA, 3 w/w% water and 0.07 w/w% photoinitiator into each microwell, evaporating the ethanol for 5 minutes, and irradiating with UV for 15 seconds. was formed. This results in hydrogels approximately 1 μm thick and forms multiple stacks of Ag NWs fully embedded in the hydrogel matrix instead of encapsulating individual Ag NWs. Three nanostructures (a nanostructure without hydrogel, an ultra-thin hydrogel encapsulated nanostructure, and a nanostructure with a thick hydrogel film) were immersed in an aqueous solution of tricyclazole for 1 hour and dried, followed by a portable Raman spectrometer with a 633 nm laser. was used to record Raman spectra. Here the concentration of tricyclazole varies from 100 ppm to 1 ppb.

The hydrogel-free nanostructures were tricyclized at 423, 524, 557, 594, 976, 1082, 1189, 1149, 1308, 1369, 1414 and 1577 cm ⁻¹ for all concentrations as shown in FIG. 10(a). It shows a clear characteristic peak of the sol. The limit of detection (LOD) is measured at 1 ppb. The ultra-thin hydrogel encapsulated nanostructure shows the intensity of the Raman signal comparable to that without the hydrogel in the range of 1 ppm to 100 ppm, as shown in FIG. 11(b), and the relative intensity is somewhat lower in the range of 1 ppb to 1 ppm . Nevertheless, the LOD is measured at 1 ppb, which is the same as for the nanostructure without hydrogel. In contrast, the nanostructure encapsulated in a thick hydrogel shows much lower strength over the entire concentration range, and the Raman signal of tricyclazole at 1 ppb concentration is not measured as shown in FIG. 10( c ). The decrease in LOD for the thick hydrogel matrix is due to the long diffusion length through the hydrogel network and partial splitting of tricyclazole in the hydrogel matrix. The concentration dependence of the Raman intensity at 1365 cm ^-1 for three different nanostructures is summarized in Fig. 10(d). The sensitivity of ultra-thin hydrogel-encapsulated nanostructures is comparable to that of nanostructures without hydrogels. In other words, it was confirmed that the sensitivity was not significantly reduced while sacrificing molecular selectivity for the ultra-thin hydrogel skin due to the very short diffusion length and negligible volume of the hydrogel matrix for partial splitting.

To verify the detection performance for complex mixtures, tricyclazole was directly detected in milk without pretreatment. The ultra-thin hydrogel encapsulated nanostructure is immersed in milk containing tricyclazole for 1 hour as shown in the left photo of FIG. 11(a). 7(f) and 7(g), the blocking threshold of permeation for ultra-thin hydrogel skin is between 4.6 nm and 6.6 nm, so that large proteins (mainly casein and albumin) and colloids in milk are filtered and The metal surface remains fresh and free from contamination. Raman spectra were measured on the nanostructures using a portable Raman spectrometer after complete drying. When the concentration of tricyclazole contained in milk is in the range of 10 ppb to 100 ppm, a clear characteristic peak is detected as shown in FIG. 11(b). For the 1 ppb concentration, no characteristic peak was detected, indicating that the LOD was 10 ppb, which is the same as the tricyclazole MRL in milk established in the EU. Molecules derived from milk do not have strong peaks. The small peak of 0 ppb for milk is also observed in the Raman spectra measured from the hydrogel-free nanostructures and from the ultra-thin hydrogel encapsulated nanostructures immersed in distilled water. is considered to be derived (see FIG. 12). We see this as a result of very small Raman scattering cross sections for small molecules in milk. The Raman intensity at 1365 cm ⁻¹ in the range of 10 ppb to 100 ppm is linearly proportional to the log concentration as shown in FIG. 12( c ). A linear fit shows a correlation coefficient of 0.98. Therefore, it can be confirmed that tricyclazole can be quantitatively and directly detected. In contrast, the hydrogel-free nanostructures exhibit a much lower Raman intensity in the range of 1 ppm to 100 ppm and no Raman signal for trisilazole at a concentration of 100 ppb, as shown in FIG. 13 . That is, the LOD is 1 ppm, which is twice that of the ultra-thin hydrogel encapsulated nanostructure as shown in FIG. 11(c). The significant decrease in LOD for bare nanostructures without hydrogel occurs due to non-specific adsorption of proteins, which interferes with the adsorption of tricyclazole molecules to the metal surface, resulting in decreased signal-to-noise ratio.

Although hydrogel skins provide molecular size selectivity, they can act as diffusion barriers and delay the Raman response. To study the effect of hydrogel skin on reaction time, hydrogel-free SERS nanostructures and ultra-thin hydrogel encapsulated nanostructures were treated with 1 ppm tricyclazole for various times of 1, 10, 30, 45 and 60 min. Raman spectra were obtained after complete drying by incubation in the milk contained therein. The Raman intensity at 1365 cm ^-1 increases with the incubation time of the two nanostructures, as shown in FIG. 14 . As expected, the hydrogel-free nanostructures showed a faster strength increase than the ultrathin hydrogel encapsulated nanostructures because the hydrogel delayed diffusion to the surface of the metal nanostructures. Nevertheless, the response times are not significantly different. The strength peaks within 30 minutes for nanostructures without hydrogels and 45 minutes for ultra-thin hydrogel encapsulated nanostructures. The slight delay is due to the thin hydrogel skin. The thickness of the expanded hydrogel skin is as small as about 32 nm, so diffusion is not significantly retarded.

Because Raman spectra are molecular-specific and serve as molecular fingerprints, various small molecules in complex mixtures can be identified at characteristic peak positions. To demonstrate the simultaneous detection of two different small molecules, tricyclazole and paraquat were immobilized in milk at a concentration of 1 ppm, and Raman spectra were measured using ultra-thin hydrogel encapsulated nanostructures. The Raman spectrum shows characteristic peaks of tricyclazole and paraquat, as shown in FIG. 15 . Paraquat has characteristic peaks at 833 and 1642 cm ⁻¹ measured in milk containing only paraquat. These results indicate that ultrathin hydrogel encapsulated nanostructures can be used for multiplex detection of small molecules in complex mixtures.

In the present invention, a 3D plasmonic complex structure encapsulated with an ultra-thin hydrogel skin showing high sensitivity of molecular detection and polymer selectivity based on hydrodynamic size exclusion of hydrogels was designed. The 3D plasmonic composite structure was composed of multi-layered Au-Ag bimetallic NWs whose surface was decorated with Ag NPs. In the nanostructure, the entire surface of the individual NWs is surrounded by a hydrogel skin with a thickness of about 21 nm while maintaining the interstitial voids between the NWs. The construction of these ultra-thin hydrogel encapsulated metal nanostructures simultaneously achieves substantial improvement in Raman signal and molecular selection, which is difficult to achieve with thick hydrogel encapsulated nanostructures and hydrogel-free bare nanostructures. Utilizing the advantages of superior sensitivity and selectivity, tricyclazole's micro-toxic fungicide can be detected directly in milk without a purification step. LOD is measured down to 10 ppb using the same portable Raman spectrometer as the MRL set by the EU. The LOD is expected to be much lower using high-precision Raman spectroscopy. This class of SERS platform offers new opportunities for fast and direct in situ detection of small toxic molecules in a variety of complex fluids, including biological fluids, food, cosmetic and environmental fluids. In addition, the protocol for coating metal surfaces with ultra-thin hydrogel skins is also promising for a variety of applications beyond SERS-based molecular detection.

Claims (20)

a metal nanowire made of a first metal; and metal nanoparticles made of a second metal formed on the surface of the metal nanowire; and
It includes a hydrogel skin surrounding the nanostructure, wherein the hydrogel skin surrounds each of the nanostructures individually, and the thickness of the hydrogel skin is 1 nm to 100 nm, a plasmonic complex structure.
According to claim 1,
The nanostructure is a plasmonic composite structure further comprising a metal coating layer made of a third metal formed between the metal nanowires and the metal nanoparticles.
According to claim 1,
The metal nanoparticles are a plasmonic composite structure formed on a metal nanowire through a self-assembled monolayer (SAM).
4. The method of claim 3,
The self-assembled monolayer is a plasmonic composite structure comprising perfluorodecanethiol (PFDT).
According to claim 1,
The first metal and the second metal are silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) and A plasmonic composite structure comprising at least one selected from the group consisting of manganese (Mn), wherein the first metal and the second metal are the same as or different from each other.
3. The method of claim 2,
The third metal is silver (Ag), gold (Au), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) and manganese (Mn). Plasmonic complex structure comprising at least one selected from the group consisting of.
According to claim 1,
A plasmonic composite structure having a diameter of 10 nm to 500 nm of the metal nanowires.
According to claim 1,
The diameter of the metal nanoparticles is 5 nm to 200 nm plasmonic composite structure.
3. The method of claim 2,
The thickness of the metal coating layer is a plasmonic composite structure of 5 nm to 50 nm.
According to claim 1,
The hydrogel skin is polyethylene glycol diacrylate (Polyethylene (glycol) Diacrylate), polyethylene glycol methyl ether acrylate, polyacrylamide (Polyacrylamide), poly (N- isopropyl acrylamide) (Poly (N-isopropylacrylamide)) and A plasmonic composite structure formed of one or more polymers selected from the group consisting of hydroxyethyl methacrylate.
delete forming a metal coating layer made of a third metal on the surface of the metal nanowire made of the first metal;
forming a self-assembled monolayer (SAM) on the metal coating layer;
forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and
Including; forming a hydrogel skin surrounding the nanostructure in the nanostructure, wherein the hydrogel skin surrounds each of the nanostructures individually, and the thickness of the hydrogel skin is 1 nm to 100 nm, A method for producing a plasmonic complex structure.
13. The method of claim 12,
Forming the metal nanoparticles is a method of manufacturing a plasmonic composite structure in which a second metal is deposited using a thermal evaporation method to form nanoparticles, and then a self-assembled monolayer film is partially removed.
Board; and
A substrate for surface-enhanced Raman spectroscopy for detecting a target material, including; the plasmonic complex structure of claim 1 formed on the substrate.
15. The method of claim 14,
The substrate is a substrate for surface-enhanced Raman spectroscopy for detecting a target material having a micro-well array structure.
15. The method of claim 14,
The substrate is selected from the group consisting of polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), silicon (Si), glass and quartz. A substrate for surface-enhanced Raman spectroscopy for detecting a target material, comprising a first layer including at least one selected material and a second layer forming a micro-well array structure.
15. The method of claim 14,
The plasmonic composite structure is a substrate for surface-enhanced Raman spectroscopy for detecting a target material in which a multiple stack of a 3D structure is formed.
preparing a substrate;
forming a metal nanowire made of a first metal on the substrate;
forming a metal coating layer made of a third metal on the surface of the metal nanowire;
forming a self-assembled monolayer (SAM) on the metal coating layer;
forming a nanostructure by forming metal nanoparticles made of a second metal on the self-assembled monolayer; and
Including; forming a hydrogel skin surrounding the nanostructure in the nanostructure, wherein the hydrogel skin surrounds each of the nanostructures individually, and the thickness of the hydrogel skin is 1 nm to 100 nm, A method of manufacturing a substrate for surface-enhanced Raman spectroscopy for target material detection.
19. The method of claim 18,
The step of preparing the substrate,
1 selected from the group consisting of polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), silicon (Si), glass and quartz A method of manufacturing a substrate for surface-enhanced Raman spectroscopy for detecting a target material, wherein a second layer for forming a micro-well array structure is formed on the first layer including at least a species of material.
A method for detecting a target material using the substrate for surface-enhanced Raman spectroscopy of claim 14 .

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