KR102257770B1 - Paper-based substrate for spectroscopic analysis and manufacturing method thereof - Google Patents

Abstract

The present invention is a paper-based base member; A bonding coating layer comprising a material containing a catechol functional group formed on the paper-based base member; And a metal-containing nanostructure formed by being bonded to the catechol functional group on the bonding coating layer. It relates to a paper-based substrate for spectroscopic analysis and a method of manufacturing the same. According to the paper-based spectroscopic analysis substrate having the above configuration, a metal-containing nanostructure is directly grown without a reducing agent and has excellent sensitivity and signal uniformity when used for spectroscopic analysis.

Description

TECHNICAL FIELD [Paper-based substrate for spectroscopic analysis and manufacturing method thereof]

The present invention relates to a paper-based substrate for spectroscopic analysis and a method of manufacturing the same.

Raman scattering is inelastic scattering in which the energy of incident light changes. When light is applied to a specific molecular sieve, it is a phenomenon in which light with a slightly different wavelength from the irradiated light is generated due to the inherent vibrational transition of the molecular sieve.

In fact, almost all organic molecules have their own Raman shift, and according to Raman spectroscopy using Raman scattering, a signal can be obtained even in the case of a nonpolar molecule with a change in the induced polarization of the molecule. In addition, since Raman spectroscopy is not affected by interference by water molecules, it is more suitable for the detection of biomolecules such as proteins and genes.

Since the wavelength of the Raman emission spectrum indicates the chemical composition and structural characteristics of the light absorbing molecule in the sample, analyzing such a Raman signal can directly analyze the material to be analyzed.

As a background technology of the present application, Korean Patent No. 10-1867670 (Patent Document 1) describes a method of manufacturing a paper-based surface-enhanced Raman scattering substrate using a continuous chemical reaction method. However, in the above patent, a reducing agent is used to reduce the metal precursor, and accordingly, processes such as a precursor adsorption step, a precursor washing step, a loading step with a reducing agent solution, and a reducing agent solution washing step are complicated, and the process is repeated several times. As a result, process control is not easy and production steps are increased.

Patent Document 1: Korean Patent No. 10-1867670

An object of the present invention is to provide a paper-based substrate for spectroscopic analysis having excellent sensitivity and signal uniformity in which metal-containing nanoparticles are directly grown without a reducing agent.

Another object of the present invention is to provide a paper-based substrate for spectroscopic analysis capable of identifying and quantitative analysis of non-labeled analytes in the field using a portable Raman spectroscopy.

Another object of the present invention is to provide a method of manufacturing a paper-based spectral analysis substrate capable of efficiently producing a paper-based spectral analysis substrate having excellent sensitivity and signal uniformity through a simple process by directly growing metal-containing nanoparticles without a reducing agent. It is to do.

The object of the present invention is not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood from the description of the detailed description.

According to one aspect, the paper-based base member; A bonding coating layer comprising a material containing a catechol functional group formed on the paper-based base member; And a metal-containing nanostructure formed by being bonded to the catechol functional group on the bonding coating layer.

According to an embodiment, the substance containing the catechol functional group is dopamine, norepinephrine, polydopamine, poly-norepinephrine, PEG-catechol. ), and PEI-catechol.

According to an embodiment, the average diameter of the metal-containing nanostructure may be 70 nm or more.

According to an embodiment, the metal-containing nanostructure may be at least one of metal-containing nanoparticles and metal-containing nanowires.

According to an embodiment, the metal may be one of Au, Ag, Al, Co, Cu, Fe, Li, Ni, Pd, Pt, Rh, Ru, and alloys thereof.

According to an embodiment, the substrate for paper-based spectroscopic analysis of the present application can quantitatively analyze pesticides.

According to an embodiment, the pesticide may be at least one or more of diquat and paraquat.

According to an embodiment, the substrate for paper-based spectroscopic analysis of the present application may have an LOD of 0.03 μg/cm 2 or less.

According to an embodiment, the size distribution of the metal-containing nanoparticles of the substrate for paper-based spectroscopic analysis of the present application may be 25% or less.

According to another aspect, a light source; The substrate for paper-based spectroscopic analysis described herein used for surface-enhanced Raman spectroscopy; And a detector for detecting Raman spectroscopy.

According to another aspect, in the method of manufacturing a substrate for paper-based spectroscopic analysis of the present application, the step of preparing a paper-based base member; Forming a bonding coating layer containing a material containing a catechol functional group on the paper-based base member; And forming a metal-containing nanostructure bonded to the catechol functional group on the bonding coating layer.

According to an embodiment, in the method of manufacturing a substrate for paper-based spectroscopic analysis, the material containing the catechol functional group is dopamine, norepinephrine, polydopamine, poly-norepinephrine. ), PEG-catechol, and PEI-catechol.

According to an embodiment, the step of forming the metal-containing nanostructure on the bonding coating layer may be formed by reduction of the metal precursor by a catechol functional group.

According to an embodiment, the forming of the metal-containing nanostructure on the bonding coating layer may include coating with at least one _{of HAuCl 4} , NaAuCl ₄ , and AgNO _{3 aqueous solution.}

According to an embodiment, the step of forming the metal-containing nanostructure on the bonding coating layer may be performed in the range of pH 2-5.

According to an embodiment, the substrate for paper-based spectroscopic analysis of the present application has excellent sensitivity and signal uniformity when used for spectroscopic analysis as metal-containing nanoparticles are directly grown without a reducing agent.

According to an embodiment, the substrate for paper-based spectroscopic analysis of the present application has a low production cost and can be mass-produced.

According to an embodiment, the substrate for paper-based spectroscopic analysis of the present application is biodegradable, and is easy to use and manufacture.

According to an embodiment, the substrate for paper-based spectroscopic analysis of the present application has excellent flexibility and is easy to apply to various three-dimensional surfaces.

According to an embodiment, the type of non-labeled analyte can be identified and quantitatively analyzed in the field using the portable Raman spectrometer of the present application.

According to an embodiment, it is possible to efficiently manufacture a paper-based substrate for spectroscopic analysis having excellent sensitivity and signal uniformity through a simple process by directly growing metal-containing nanoparticles without a reducing agent.

1A is a schematic diagram schematically showing the structure of a substrate for paper-based spectroscopic analysis according to an embodiment.
1B is a schematic diagram schematically showing a method of manufacturing a substrate for paper-based spectroscopic analysis according to an embodiment.
Figure 2a is an untreated cellulose filter paper (Bare Cellulose Filter Paper, Bare-CFP), polydopamine-coated CFP (PD-coated CFP), paper-based SERS substrate prepared at various pH (CFP / PD / Au pH 3, CFP/PD/Au pH 5, CFP/PD/Au pH 8).
2B is a UV-Vis reflection spectrum of untreated cellulose filter paper, polydopamine-coated CFP, and paper-based SERS substrates prepared at various pHs.
2C is a scanning electron microscope (SEM) image of gold nanoparticles (AuNP) formed on the CFP of a paper-based SERS substrate prepared at various pHs (scale bar: 200 nm, left: pH 3, center: pH 5, right: pH 8).
Figure 2d is a graph showing the diameter size distribution of the AuNP of Figure 2c.
3A is an SEM image showing an energy dispersive X-ray spectroscopy (EDS) analysis site for confirming the formation of gold nanoparticles (AuNP) on CFP.
3B is a graph showing the results of an energy dispersive spectroscopic analysis of the analysis portion of FIG. 3A.
3C is an SEM image showing that AuNPs are not formed on the cellulose filter paper when the untreated cellulose filter paper (bare CFP) _{is immersed in a HAuCl 4 solution of pH 3.}
FIG. 3D is a SEM image showing a shape in which only some AuNPs are attached on the cellulose filter paper when the polydopamine-coated cellulose filter paper (PD-coated CFP) is immersed in a 40 nm-sized AuNP preformed solution.
4A is a view showing a result of a Finite-Difference Time-Domain (FDTD) simulation of an electromagnetic field formed according to various distances between metal-containing nanoparticles having a diameter of 102 nm.
FIG. 4B is a diagram showing FDTD simulation results of an electromagnetic field formed according to the distance between metal-containing nanoparticles having a diameter of 70 nm.
FIG. 4C is a diagram showing FDTD simulation results of an electromagnetic field formed according to the distance between metal-containing nanoparticles having a diameter of 36 nm.
4D is a diagram showing the results of FDTD simulation of an electromagnetic field according to the size of a single metal-containing nanoparticle.
5A is a graph showing a Raman signal of methylene blue having the same concentration measured using a paper-based SERS substrate prepared in _{a HAuCl 4} solution of various pH.
5B is a graph showing the result of measuring the detection limit (LOD) of methylene blue using a paper-based SERS substrate prepared in _{a HAuCl 4} solution of pH 3.
5C is a graph showing a calibration curve of methylene blue concentrations of various concentrations of FIG. 5B.
5D is a diagram showing the Raman signal uniformity for methylene blue of a paper-based SERS substrate prepared in _{a HAuCl 4 solution at pH 3. FIG.}
6A is a graph showing a result of measuring a detection limit (LOD) of a diquat (DQ) using a paper-based SERS substrate.
6B is a graph showing a calibration curve of DQ concentrations of various concentrations of FIG. 6A.
6C is a diagram showing Raman signal uniformity for DQ of a paper-based SERS substrate.
6D is a graph showing the result of measuring the detection limit (LOD) of paraquat (PQ) using a paper-based SERS substrate.
6E is a graph showing a calibration curve of PQ concentrations of various concentrations of FIG. 6D.
6F is a diagram showing Raman signal uniformity for PQ of a paper-based SERS substrate.
7A is a schematic schematic diagram showing a method of detecting residual pesticides on the surface of an apple using a paper-based SERS substrate.
7B is a graph showing a Raman signal of DQ pre-processed on apples at various concentrations measured according to FIG. 7A.
7C is a graph showing a Raman signal of PQ pre-processed on apples at various concentrations measured according to FIG. 7A.
8A is a photograph showing the flexibility of a paper-based SERS substrate.
8B is a photograph showing that a paper-based SERS substrate is put in a device capable of a bending test and tested for 1000 times at 90 rpm with a bending radius of 7 mm.
FIG. 8C is a graph showing the results of measuring the Raman signal of methylene blue before and after the bending experiment of the paper-based SERS substrate according to FIG. 8B.

Objects, specific advantages, and novel features of the present disclosure will become more apparent from the following detailed description and embodiments in conjunction with the accompanying drawings.

Prior to this, terms or words used in the present specification and claims should not be interpreted in a conventional and dictionary meaning, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present disclosure based on the principle that there is.

In this specification, when a component such as a layer, portion, or substrate is described as being “on”, “connected”, or “coupled” to another component, it is directly “on”, “on” the other component. It may be connected" or "coupled", and may be interposed between one or more other components. In contrast, if a component is described as being "directly over", "directly connected", or "directly coupled" of another component, no other component can be interposed between the two components. .

The terms used in this specification are used only to describe specific embodiments, and are not intended to limit the present disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof does not preclude in advance.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. In addition, throughout the specification, "on" means to be positioned above or below the target portion, and does not necessarily mean to be positioned above the direction of gravity.

Since the present disclosure may apply various transformations and may have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present disclosure to a specific embodiment, it is to be understood as including all conversions, equivalents, and substitutes included in the spirit and scope of the present disclosure. In describing the present disclosure, when it is determined that a detailed description of related known technologies may obscure the subject matter of the present disclosure, a detailed description thereof will be omitted.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding constituent elements are assigned the same reference numbers, and redundant descriptions thereof will be omitted. do.

1A is a schematic diagram schematically showing the structure of a substrate for paper-based spectroscopic analysis according to an embodiment, and FIG. 1B is a schematic diagram schematically showing a method of manufacturing a substrate for paper-based spectroscopic analysis according to an embodiment.

1A and 1B, a paper-based spectral analysis substrate 100 according to an embodiment of the present application includes a paper-based base member 10; A bonding coating layer 20 comprising a material containing a catechol functional group formed on the paper-based base member 10; And a metal-containing nanostructure 30 formed by being bonded to the catechol functional group on the bonding coating layer 20.

The paper-based base member 10 is inexpensive, capable of mass production, biodegradable, easy to use and manufacture, excellent absorbency, and is flexible, so that a member that can be easily attached to various surfaces is suitable. , There are no special restrictions. Although not limited thereto, the paper-based base member 10 may be cellulose filter paper (CFP).

Materials containing the catechol functional group forming the bonding coating layer 20 are dopamine, norepinephrine, polydopamine, poly-norepinephrine, and PEG-catechol ( PEG-catechol), and PEI-catechol.

Although not limited thereto, dopamine may be suitable as the material containing the catechol functional group. The dopamine _{has a chemical formula of C 8} H ₁₁ NO ₂ and a molecular weight of 153.18. It is the first catecholamine produced in the reaction by the aromatic-L-amino acid decarboxylase of L-dopa, and is a precursor to norepinephrine and epinephrine. When such dopamine is polymerized, polydopamine (PD) is produced, and the polydopamine can be used as a coating material that can modify various surfaces to have certain chemical properties regardless of their structure and material, and has excellent adhesion. Do.

Conventionally, in order to form a metal-containing nanostructure on a paper-based base member, a reducing agent is used, and accordingly, processes such as a metal precursor adsorption step, a precursor washing step, a loading step with a reducing agent solution, and a reducing agent solution washing step are complicated and the above process. There is a problem in that the process control is not easy and the production step is increased by repeatedly performing the process several times. However, in the present application, this problem is solved by forming the bonding coating layer 20 using a material containing a catechol functional group. That is, when metal nanoparticles are grown on a paper-based base member, the catechol functional group plays a role of catching metal ions and a reducing agent at the same time, so that the metal nanoparticles spontaneously grow on the paper-based base member without using a reducing agent separately. It will be.

The metal-containing nanostructure 30 is formed by being bonded to the catechol functional group on the bonding coating layer 20. In the present application, it is characterized in that the metal-containing nanostructure 30 is bonded to the catechol functional group by spontaneous reduction. The metal-containing nanostructure 30 is characterized in that a nanogap is formed between the metal-containing nanostructures 30 on the paper-based base member 10, and the nanogap is uniformly formed.

According to an embodiment, the metal-containing nanostructure 30 may be at least one of metal-containing nanoparticles and metal-containing nanowires, but the metal-containing nanoparticles have excellent adhesion and distribution uniformity with the bonding coating layer 20 can do.

The average diameter of the metal-containing nanostructure may be 70 nm or more. The average diameter of the metal-containing nanostructure can be adjusted according to the pH when forming the metal-containing nanostructure, but the average diameter of the metal-containing nanostructure is 70 nm or more is helpful for Raman signal amplification, and 80 nm or more may be suitable, It may be suitable that it is 90 nm or more, and it may be suitable that it is 100 nm or more. Here, the diameter refers to the average diameter when the nanospheres are nanoparticles, and when the nanostructures are nanowires, it refers to the average diameter of the cross-section of the nanowires.

The metal may be one of Au, Ag, Al, Co, Cu, Fe, Li, Ni, Pd, Pt, Rh, Ru, and alloys thereof, but is not limited thereto, but Au is a Raman signal amplification and bonding coating layer ( It may be suitable from the viewpoint of adhesion with 20). In addition, Au is excellent in high temperature, chemical and photochemical stability.

The substrate for paper-based spectroscopic analysis of the present application may be used for qualitative and/or quantitative analysis of target analytes from various biological samples, foods, and the like. Although not limited thereto, the substrate for paper-based spectroscopic analysis of the present application can be used for qualitative and/or quantitative analysis of chemical substances, and in particular, for qualitative and quantitative analysis of pesticides remaining in foods having a three-dimensional surface such as fruits. Can be used to

Although not limited thereto, the pesticide may be at least one or more of diquat and paraquat. Diquat and paraquat are representative bipyridylium herbicides, which are harmful to humans and animals. Therefore, there is a maximum residual concentration (MRL) standard for diquats and paraquats, and there is a high need to measure them. The MRL of diquat and paraquat in the United States, Europe and China is calculated by the following equation and is 31.1 μg/cm 2.

The substrate for paper-based spectroscopic analysis of the present application may have an LOD of 0.5 ppm (0.03 μg/cm 2) or less for pesticides. Since 1 ppm is 0.125 μg/cm 2 according to the above equation, the paper-based spectral analysis substrate of the present application can accurately measure whether the MRL standard is met.

In addition, the substrate for paper-based spectroscopic analysis of the present application has excellent sensitivity with an LOD of 100 nM (2 ng/cm 2) for methylene blue.

The diameter size distribution of the metal-containing nanoparticles of the substrate for paper-based spectroscopic analysis of the present application may be 25% or less. Therefore, the use of the paper-based spectral analysis substrate of the present application has a high signal uniformity, thereby enabling high reproducibility and accurate quantitative analysis.

According to another aspect, a light source; The substrate for paper-based spectroscopic analysis described herein used for surface-enhanced Raman spectroscopy; And a detector for detecting Raman spectroscopy.

As the light source, a laser capable of providing high-power incident light as used in a general Raman spectroscopy device may be used.

The Raman spectroscopy device may be portable. As described above, the substrate for paper-based spectroscopic analysis of the present application has excellent sensitivity and signal uniformity, so that on-site diagnosis is possible by accurate qualitative and quantitative analysis in the field. Therefore, it is possible to directly analyze biological samples such as blood and urine, chemical substances, or environmental pollutants in the field without a separate labeling substance.

As the detector, it may be appropriate to include a photomultiplier tube (PMT), an avalanche photodiode (APD), a charge coupled device (CCD), and the like capable of effectively amplifying the detection signal.

According to another aspect, in the method of manufacturing a substrate for paper-based spectroscopic analysis of the present application, the step of preparing a paper-based base member; Forming a bonding coating layer containing a material containing a catechol functional group on the paper-based base member; And forming a metal-containing nanostructure bonded to the catechol functional group on the bonding coating layer.

1B is a schematic diagram schematically showing a method of manufacturing a substrate for paper-based spectroscopic analysis according to an embodiment.

Referring to FIG. 1B, in the step of preparing the paper-based base member 10, it is inexpensive, mass-producible, biodegradable, easy to use and manufacture, and is flexible, so that it can be easily attached to various surfaces. Prepare a paper-based base member 10 that can be. Although not limited thereto, the paper-based base member 10 may be cellulose filter paper (CFP).

Next, the bonding coating layer 20 including a material containing a catechol functional group on the paper-based base member 10 may be formed by various known methods. For example, bonding containing a material containing a catechol functional group on the paper-based base member 10 by using, for example, dip-coating, spin coating, drop casting, and spray method. The coating layer 20 may be formed.

In the method of manufacturing a substrate for spectroscopic analysis, the material containing the catechol functional group is dopamine, norepinephrine, polydopamine, poly-norepinephrine, PEG-catechol. -catechol), and PEI-catechol (PEI-catechol).

Although not limited thereto, in the embodiment, the paper-based base member 10 is immersed in a dopamine solution to polymerize polydopamine to form the bonding coating layer 20.

The concentration of the dopamine solution may be 0.5 mg/mL to 10 mg/mL. Although not limited thereto, if the concentration of the dopamine solution is less than 0.5 mg/mL, the spontaneous growth of metal-containing nanostructures may not be easy, and if it exceeds 10 mg/mL, the spontaneous growth of the metal-containing nanostructures increases with increasing concentration. Rather, it can be hindered.

The step of forming the metal-containing nanostructure 30 on the bonding coating layer 20 may be formed by spontaneous reduction of the metal precursor by a catechol functional group. The material containing the catechol functional group serves to capture metal ions and to reduce metal precursors without a reducing agent. Therefore, it is possible to manufacture a paper-based substrate for spectroscopic analysis by one immersion, so that the process is simple, mass production is possible, and the manufacturing cost can be lowered.

The step of forming the metal-containing nanostructure 30 on the bonding coating layer 20 may be formed by coating a metal precursor solution on the bonding coating layer 20. The coating includes known methods such as dip-coating, spin coating, drop casting, and spray method.

The metal precursor solution is not particularly limited as long as it contains a metal ion capable of reacting with a substance containing a catechol functional group. For example, the metal precursor solution _{may be at least one of HAuCl 4} , NaAuCl ₄ , and AgNO ₃ aqueous solution, and mixing or sequential use of the metal precursor solution is not excluded. In the embodiment of the present application, the CFP on which the bonding coating layer 20 is formed is used as HAuCl ₄ It was immersed in the solution to form a metal-containing nanostructure.

The metal ion concentration of the metal precursor solution may be 0.5 mg/mL to 100 mg/mL. Although not limited thereto, if the metal ion concentration of the metal precursor solution is less than 0.5 mg/mL, spontaneous growth of the metal-containing nanostructure may not be easy, and if it exceeds 100 mg/mL, the metal-containing nanostructure may not be easily grown. Spontaneous growth may be rather inhibited or nanogap formation may be inhibited.

The step of forming the metal-containing nanostructure 30 on the bonding coating layer 20 may be performed in the range of pH 2-5. Although not limited thereto, forming the metal-containing nanostructure 30 in the pH range of 2-5 is suitable for increasing the diameter of the metal-containing nanostructure 30 and making the diameter distribution uniform, and pH 2- 4 may be more suitable.

Referring to Figure 1b, when the paper-based spectroscopic analysis substrate of the present application is in contact with an analyte, the analyte is easily absorbed due to the characteristics of the paper, and the laser of the spectrometer is output to the spectroscopic analysis substrate in which the analyte is absorbed Thus, the Raman signal of the analyte can be amplified into a detection signal with a detector to check the type of analyte and perform quantitative analysis. Therefore, it is possible to easily absorb and separate an analyte using the paper-based spectroscopic analysis substrate of the present application, and at the same time confirm the type of absorbed analyte and perform quantitative analysis.

Hereinafter, a preferred embodiment is presented to aid the understanding of the present invention. However, the following examples are provided for easier understanding of the present invention, and the contents of the present invention are not limited by the examples.

[ Example ]

Materials

Dopamine hydrochloride, tris(hydroxymethyl)aminomethane, HAuCl ₄ 3H ₂ O, methylene blue (MB), methyl viologen dichloride monohydrate , PQ), and diquat dibromide monohydrate (DQ) were purchased and used from Sigma-Aldrich (St. Louis, MO, USA). Cellulose filter paper (CFP) was used by purchasing a product with a pore size of 0.45 μm from Hyundai Micro Co., LTD, Seoul, South Korea.

Example 1. Paper-based SERS Substrate fabrication

Paper-based SERS The substrate was prepared using a simple dip coating method.

First, cellulose filter paper (CFP) was immersed in 1 mg/mL of a dopamine-Tris buffer solution (10 mL, pH 8.5) and stirred at room temperature for 24 hours to cause polymerization of dopamine on the CFP surface.

After the polymerization reaction, the sample was washed with distilled water and dried at 45°C. Then, a 1 mg/mL solution of HAuCl _{4 at} pH 3, pH 5, and pH 8 was separately prepared, and the cellulose filter paper coated with polydopamine (PD) was immersed at room temperature for 24 hours. After AuNP nucleation was formed, the prepared substrate was washed with distilled water and then dried in air to prepare a paper-based SERS substrate.

Comparative Examples 1 and 2. Preparation of control paper-based substrate

As control substrates, cellulose filter paper (Comparative Example 1) in which untreated cellulose filter paper (bare CFP) was directly _{immersed in HAuCl 4} solution of pH 3 and polydopamine-coated cellulose filter paper (PD-coated CFP) were averaged. A cellulose filter paper (Comparative Example 2) immersed in a solution in which AuNPs having a diameter size of 40 nm was prepared in advance.

Experimental example 1. Paper-based SERS Characteristics of the substrate

The surface shape of the paper-based SERS substrate was observed with an electron microscope (FE-SEM; Joel JSM-6700F). In addition, elemental analysis was performed using an energy dispersive spectrometer (EDS) provided in the FE-SEM. The average particle diameter and dispersion of AuNPs formed in different pH solutions were obtained by measuring 100 different nanoparticles in SEM images. The UV-vis reflection spectrum of the paper-based substrate formed at each pH was measured using a reflective UV-visible spectrophotometer (UV-vis-NIR spectrophotometer, Cary 5000, Agilent Technology). The results are shown in FIGS. 2A to 2D.

As shown in Figure 2a, from the left, untreated cellulose filter paper (Bare Cellulose Filter Paper, Bare-CFP) is white, and polydopamine-coated CFP (PD-coated CFP) is shown in gray. In addition, when immersed in three gold precursor solutions with different pH (CFP/PD/Au pH 3, CFP/PD/Au pH 5, CFP/PD/Au pH 8), as the pH increases after 24 h, reddish brown, purple, and dark colors respectively It could be confirmed that it changed to purple.

As shown in FIG. 2B, as a result of confirming by UV-vis reflectance, when immersed in the gold precursor solution of pH 3, the SPR peak (Surface Plasmon Resonance peak) was confirmed, and the diameter size of the nanoparticles was predictable to be about 100 nm.

As shown in FIG. 2C, as a result of measuring the diameter of the gold nanoparticles formed on the cellulose filter paper immersed in the gold precursor solution at each pH through SEM images, pH 3 was 102 nm, pH 5 was 70 nm, and pH 8 Was able to confirm the average diameter of 36 nm.

As shown in FIG. 2D, as a result of confirming the diameter distribution of gold nanoparticles formed on the cellulose filter paper immersed in the gold precursor solution at each pH, the 102 nm particle had the best diameter size uniformity. That is, as shown in Figure 2d, the diameter distribution of the gold nanoparticles formed on the cellulose filter paper immersed in the gold precursor solution of each pH 3, pH 5, pH 8 is 102 ± 24.3 nm, 70 ± 26.8 nm, and 36 ± 6.6 nm.

3A is an SEM image showing an energy dispersive X-ray spectroscopy (EDS) analysis site for confirming the formation of gold nanoparticles (AuNP) on CFP, and FIG. 3B is an analysis site of FIG. 3A. This is a graph showing the results of energy dispersive spectroscopy. 3A and 3B, although the reducing agent was not used, it was confirmed that the formed nanoparticles were reduced gold.

On the other hand, as shown in FIG. 3C, when the untreated cellulose filter paper (bare CFP) was directly _{immersed in the HAuCl 4} solution (Comparative Example 1), AuNP was not formed on the cellulose filter paper due to the absence of the polydopamine layer. Confirmed. In addition, as shown in Figure 3d, when the cellulose filter paper (PD-coated CFP) coated with polydopamine is immersed in a solution in which AuNP is formed in advance (Comparative Example 2), some AuNPs form clusters on the cellulose filter paper. It was confirmed that there was a shape attached to the surface, but AuNP was not uniformly distributed.

Experimental example 2. Electromagnetic field distribution simulation

The optical properties of plasmonic nanostructures were analyzed using a three-dimensional finite difference time domain simulation. The mesh size was set to 0.5 nm for the AuNP average diameter 36 nm, 70 nm, and 102 nm. The refractive indices of paper and air were set to 1.557 and 1.0, respectively. The gap between the two AuNPs was set to 5, 10, 20, 40, 60 and 100 nm. The optical excitation direction was set to a direction perpendicular to the plane of the paper substrate. Near-field enhancement was calculated by the following equation. E, E ₀ and V represent the maximum electromagnetic field, the intensity of the incident light, and the volume, respectively.

The lorentz-drude dispersion model was used to analyze the dielectric constant model of the nanostructure, and the following equation was used. w _p , f ₀ , and Γ ₀ represent the plasma frequency, oscillator length, and attenuation constant, respectively. In addition, Lorentz correction factors m, w _j , f _j , and Γ _j represent the number of oscillations, frequency, and damping constants, respectively.

As described above, the electromagnetic field formation was simulated according to the diameter size and distance of the nanoparticles, and the results are shown in FIGS. 4A to 4D.

As shown in FIG. 4A, when the diameter of the nanoparticles is 102 nm, a strong electromagnetic field is formed between the particles as the distance between the two particles is closer, and when the distance between the nanoparticles is 60 nm or more, it is similar to the existence of a single particle. The results appeared. For reference, the darker the red color, the stronger the electromagnetic field.

As shown in FIGS. 4B and 4C, as the distance between the nanoparticles increases, the electromagnetic field amplification effect decreases as shown in FIG. 4A. The initial electromagnetic field intensity decreased in the order of nm. That is, it was confirmed that particles having a large diameter of nanoparticles are also advantageous in amplifying an electromagnetic field.

As shown in FIG. 4D, when the diameter of the nanoparticles is 102 nm, the electromagnetic field amplification phenomenon occurs even when the particle diameter is large and exists as a single nanoparticle. As the size of the direct impact of the nanoparticles decreased to 36 nm, the effect of amplifying the electromagnetic field of the single particle gradually decreased.

Experimental example 3. LOD And Raman signal uniformity experiment

The detection limit experiment of the paper-based SERS substrate prepared at pH 3 was carried out with a volume of 10 μL of methylene blue, diquat, and paraquat solutions. The size of the paper-based substrate was fixed to a square of 0.16 cm2. The volume of methylene blue solution was 5 μM, 1 μM, 500 nM, 200 nM, and 100 nM, and the volume of diquat and paraquat was 50 ppm, 25 ppm, 10 ppm, 5 ppm, 1 ppm and 0.5 ppm, respectively. Each Raman detection was measured after the solution was dried.

In addition, in order to confirm the uniformity of the Raman signal, Raman mapping imaging was performed on a 200 μm x 200 μm area at 20 μm intervals. In order to compare the Raman signal size of the paper-based SERS substrates prepared under different pH conditions, methylene blue was 200 ng/cm 2 and diquat and paraquat were volumetrically compared at a concentration of 3.125 μg/cm 2 for each pH condition. For all Raman signals, portable Raman equipment was used, and for methylene blue, a wavelength of 633 nm, laser power of 0.5 mW, irradiation time of 0.5 s, and laser diameter of 1.68 μm were used (NS220 for 633 nm, Inc., Daejeon, South Korea). . For the detection of pesticides, a wavelength of 785 nm, a power of 1 mW, an irradiation time of 5 s, and a laser diameter of 2.08 μm were used (NS200 for 785nm Inc., Daejeon, South Korea). All spectra were obtained from 15 random locations and then averaged and displayed.

The experiment was conducted as described above and the results are shown in FIGS. 5A to 6F.

As shown in FIG. 5A, as a result of comparing the Raman signal of the same concentration of methylene blue on the paper-based SERS substrate prepared under each pH condition, the strongest Raman signal was obtained in the paper-based SERS substrate prepared at pH 3.

As shown in FIGS. 5B and 5C, the detection limit of methylene blue was measured using a paper-based SERS substrate prepared at pH 3, and as a result, it was possible to detect up to 100 nM.

As shown in FIG. 5D, Raman mapping was performed to confirm the uniformity of the Raman signal of the paper-based SERS substrate, and a uniform Raman signal was obtained as a whole. As a result of plotting 15 Raman spectra of each, a uniform Raman spectrum could be obtained.

As shown in FIGS. 6A to 6C, it was confirmed that up to 0.5 ppm of the die quart pesticide can be detected using the paper-based SERS substrate of the present application, and the qualitativeness of die quart by confirming the signal uniformity through the corresponding calibration curve and Raman mapping. And it was confirmed that the quantitative analysis can be carried out reproducibly.

As shown in FIGS. 6D to 6F, it was confirmed that up to 0.5 ppm of paraquat pesticides can be detected using the paper-based SERS substrate of the present application, and the qualitative and quantification of paraquat by confirming the signal uniformity through the corresponding calibration curve and Raman mapping. It was confirmed that the analysis can be carried out reproducibly.

Experimental example 4. Paper-based SERS Residual pesticide detection experiment for on-site application of substrates

Analysis of pesticide residues for field application was conducted. 20 μL of diquat and paraquat solutions were prepared at 50, 25, 10, 5, 1 ppm each, contaminated with apple peels in advance, and dried for 24 hours. The area treated with the pesticide was 0.13 cm 2.

10 μL of distilled water was applied to a paper-based SERS substrate (4 mm x 4 mm in size) and attached for 10 minutes near the pesticide contamination of apple peels to extract pesticides. Raman signals were measured on the detached paper-based SERS substrate using a portable Raman spectrometer with a wavelength of 785 nm, power of 1 mW, and irradiation time of 5 seconds.

The experiment was conducted as described above and the results are shown in FIGS. 7A to 7C.

As shown in FIG. 7A, the paper-based SERS substrate has excellent flexibility and can be easily attached to the apple surface. As shown in FIG. 7B, the detection limit on the apple surface for the diquat pesticide was 1 ppm, and as shown in FIG. 7C, the detection limit on the apple surface for the paraquat pesticide was 1 ppm.

After the solution on the paper-based SERS substrate is dried, Raman is measured. Even with the same concentration of solution, if the volume is increased, the signal may be stronger. Therefore, it can be expressed by dividing the absolute quantity (g) by the unit area (refer to the equation below). Therefore, 1 ppm of pesticide detection limit of the paper-based SERS substrate corresponds to 0.125 μg/cm 2.

Experimental example 5. Paper-based SERS Board flexibility test

A 47 mm diameter cellulose filter paper was prepared to prepare a paper-based SERS substrate coated with AuNP in an Au precursor solution of pH 3. The following paper-based SERS substrate was cut into a 1 cm x 4 cm rectangular size, and 10 μL of methylene blue at a concentration of 10 μM was added to the center. For the bending test, which is one of the flexibility tests of the material, the bending radius of the bending test apparatus was set to 7 mm, and bending tests were performed at a speed of 90 rpm for 1000 cycles. It was attempted to confirm the stability as a flexible substrate by measuring the Raman signal of methylene blue every 200 cycles of the bending experiment.

The experiment was conducted as described above and the results are shown in FIGS. 8A to 8C. As shown in FIGS. 8A to 8C, it was confirmed that the flexibility of the paper-based SERS substrate was excellent, and in particular, the Raman signal was well maintained even after a bending test of 1000 cycles.

The inherent flexibility of such a paper-based SERS substrate can increase the scalability as a Raman substrate and can be applied to various three-dimensional surfaces.

Furthermore, the paper-based SERS substrate has the advantage of being able to rapidly adsorb an analyte in a solution state due to its excellent hygroscopicity.

Although the SERS substrate has been described above, it is not limited thereto, and the paper-based spectral analysis substrate of the present application may be used for various spectral analysis. For example, the substrate for paper-based spectroscopic analysis of the present application may be a substrate for surface-enhanced Raman scattering or a substrate for surface-enhanced infrared absorption analysis. Therefore, the present application can be applied to infrared (IR) spectroscopy in addition to Raman analysis using visible light.

As described above, specific parts of the present invention have been described in detail, and for those of ordinary skill in the art, it is obvious that this specific technique is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Therefore, it will be said that the practical scope of the present invention is defined by the appended claims and their equivalents.

10: base member
20: bonding coating layer
30: metal-containing nanostructure
100: substrate for paper-based spectroscopic analysis

Claims (15)

A paper-based base member;
A bonding coating layer comprising a material containing a catechol functional group formed on the paper-based base member; And
Including; a metal-containing nanostructure formed by being bonded to the catechol functional group on the bonding coating layer,
The average diameter of the metal-containing nanostructure is 70 nm or more,
A paper-based substrate for spectroscopic analysis with improved flexibility and attachable to the surface of a 3D analysis target.
The method of claim 1,
The substances containing the catechol functional group are dopamine, norepinephrine, polydopamine, poly-norepinephrine, PEG-catechol, and PEI-catechol. A substrate for paper-based spectroscopy, selected from PEI-catechol.
delete The method of claim 1,
The metal-containing nanostructure is at least one or more of metal-containing nanoparticles and metal-containing nanowires, a paper-based substrate for spectroscopic analysis.
The method of claim 1,
The metal is one of Au, Ag, Al, Co, Cu, Fe, Li, Ni, Pd, Pt, Rh, Ru, and alloys thereof, a paper-based substrate for spectroscopic analysis.
The method of claim 1,
A paper-based substrate for spectroscopic analysis that can quantitatively analyze pesticides.
The method of claim 6,
The pesticide is diquat (diquat) and paraquat (paraquat) of at least one or more of, a paper-based substrate for spectroscopic analysis.
The method of claim 1,
LOD of 0.03 ㎍ / ㎠ or less, a substrate for paper-based spectroscopic analysis.
The method of claim 1,
A substrate for paper-based spectroscopic analysis with a size distribution of less than 25% of metal-containing nanostructures.
Light source;
The paper-based spectroscopic analysis substrate according to any one of claims 1, 2, and 4 to 9 used for surface-enhanced Raman spectroscopy; And
Raman spectroscopy device comprising; a detector for detecting Raman spectroscopy.
A method for manufacturing a paper-based spectral analysis substrate for spectral analysis according to claim 1,
Preparing a paper-based base member;
Forming a bonding coating layer containing a material containing a catechol functional group on the paper-based base member; And
Forming a metal-containing nanostructure bonded to the catechol functional group on the bonding coating layer; Including,
The step of forming the metal-containing nanostructure on the bonding coating layer is performed in the range of pH 2-5,
A method of manufacturing a paper-based substrate for spectroscopic analysis, characterized in that no reducing agent is used.
The method of claim 11,
The substances containing the catechol functional group are dopamine, norepinephrine, polydopamine, poly-norepinephrine, PEG-catechol, and PEI-catechol. Cole (PEI-catechol), a method of manufacturing a substrate for paper-based spectroscopic analysis.
The method of claim 11,
The step of forming the metal-containing nanostructure on the bonding coating layer is formed by reduction of the metal precursor by a catechol functional group, a method of manufacturing a paper-based substrate for spectroscopic analysis.
The method of claim 11,
Forming the metal-containing nanostructure on the bonding coating layer comprises coating with at least one of HAuCl ₄ , NaAuCl ₄ , and AgNO ₃ aqueous solution.
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