Thiol-modified surface-enhanced Raman scattering composite substrate and its preparation method and application

Abstract

The present invention relates to the field of surface-enhanced Raman spectroscopy detection technology, and discloses a thiol-modified surface-enhanced Raman scattering composite substrate, a preparation method thereof, and an application thereof. The composite substrate comprises a substrate, silver nanowires attached to the substrate, gold nanospheres, and thiols modified on the silver nanowires and the gold nanospheres. The composite substrate provided by the present invention combines gold nanospheres with silver nanowires to form a three-dimensional nanostructure of silver nanowire-gold nanospheres, and the three-dimensional nanostructure of the silver nanowire-gold nanospheres is modified with thiol. The obtained composite substrate of the present invention has high detection sensitivity for substances (such as organic pollutants). In addition, the present invention also provides a method for preparing a thiol-modified surface-enhanced Raman scattering composite substrate, which is simple and quick to self-assemble by solution volatilization and does not involve expensive instruments; at the same time, the substrate is solid, which is conducive to storage and operation, thereby facilitating further promotion and application.

Description

Technical Field

[0001] The present invention relates to the technical field of surface enhanced Raman spectroscopy detection, and in particular to a thiol-modified surface enhanced Raman scattering composite substrate, a preparation method thereof, and applications thereof. Background Art

[0002] Polycyclic aromatic hydrocarbons (PAHs) are products of the incomplete combustion of fossil fuels or carbon-containing materials such as wood and tobacco. They are mostly compounds containing two or more benzene rings in a fused ring structure. As a class of persistent organic pollutants (POPs), PAHs have the following characteristics: 1. They are numerous, including over hundreds of naphthalene, anthracene, phenanthrene, pyrene, and their derivatives; 2. They are widely distributed, commonly found in the atmosphere, soil, water, and various solid pollutants; 3. They persist for a long time and are difficult to degrade; 4. They are highly mutagenic and carcinogenic, making them significant environmental and food contaminants, posing a significant threat to the deteriorating ecological environment and human health. Currently, PAH detection methods primarily include capillary electrophoresis, gas chromatography-mass spectrometry, and fluorescence spectroscopy. While these methods are highly sensitive, they require complex sample pretreatment, tedious procedures, and are often performed only under laboratory conditions. Therefore, establishing a fast, real-time and simple PAH detection and analysis technology has important practical significance for the sustainable development of the environment and human survival.

[0003] As an emerging detection method, surface enhanced Raman scattering (SERS) technology has the advantages of high sensitivity, rich chemical fingerprint information, simple operation, and the ability to achieve in-situ detection. The enhancement effect of the SERS substrate depends on the electromagnetic field enhancement ("hotspot") area on the surface of the structure. The greater the density and intensity of the "hotspot", the more obvious the enhancement effect of the SERS substrate. In addition, to detect PAHs through SERS technology, PAHs need to be adsorbed onto the SERS substrate. Since PAHs are mostly benzene ring structures with fewer substituents, it is difficult to directly adsorb them to the substrate through covalent bonds. They are more likely to be connected to the substrate through non-covalent bond forces (such as the hydrophobic effect of long-chain alkanes). At present, there have been some reports on the detection of polycyclic aromatic hydrocarbons using SERS technology.

[0004] CN102608101A discloses a surface-enhanced Raman active substrate for highly sensitive detection of polycyclic aromatic hydrocarbons in water. The substrate uses a gold sol system with optimized parameters as a surface Raman enhanced substrate to achieve detection of polycyclic aromatic hydrocarbons in water.

[0005] CN103994992A discloses a method for SERS detection of polycyclic aromatic hydrocarbons and their substituents based on a cucurbituril-modified substrate, the steps of which are as follows: (1) preparing a deionized water solution of gold sol; (2) dissolving cucurbituril CB[n] and diluting it to a desired concentration, where n is 6-10; (3) mixing the solution prepared in step (1) with the solution diluted in step (2); (4) dissolving the polycyclic aromatic hydrocarbons and their substituents to be detected qualitatively and traceably in an organic solvent to prepare a solution of the polycyclic aromatic hydrocarbons and their substituents to be detected; (5) mixing the solution to be detected prepared in step (4) and the solution in step (3) in equal volumes. Mix, then centrifuge the mixed solution, and finally dilute it with distilled water to the original mixed solution volume; (6) take 10 microliters of the solution in step (5) and drop it on a glass slide that has been cleaned and dried, dry it at room temperature, and then perform surface enhanced Raman detection to obtain a surface enhanced Raman spectrum of the polycyclic aromatic hydrocarbons and their substituents to be tested; (7) compare the Raman spectrum of step (6) with the peak position and peak intensity of the surface enhanced Raman spectrum of the polycyclic aromatic hydrocarbons and their substituents of known concentrations under the same test conditions, so as to achieve qualitative and trace detection of the polycyclic aromatic hydrocarbons and their substituents to be tested.

[0006] CN104089942A discloses a surface-enhanced Raman substrate with superhydrophobic properties, which is prepared by the following steps: (a) cleaning nickel foam; (b) immersing the nickel foam in an aqueous solution of a noble metal salt to prepare a SERS substrate; and (c) modifying the prepared SERS substrate with long alkyl chain thiol molecules to obtain a surface-enhanced Raman substrate with superhydrophobic properties.

[0007] The above-mentioned defects involve the complex preparation process of surface-enhanced Raman scattering composite substrates for detecting polycyclic aromatic hydrocarbons, the substrates are mostly solutions that are not easy to store, and the low density of the electromagnetic field enhancement area. Therefore, it is necessary to seek a surface-enhanced Raman scattering composite substrate that is simple to prepare and has high detection sensitivity. Summary of the Invention

[0008] The purpose of the present invention is to overcome the technical problems of the prior art, such as the complex preparation process, the substrate being mostly a solution that is inconvenient to store, and the low density of the electromagnetic field enhancement area, and to provide a thiol-modified surface-enhanced Raman scattering composite substrate and its preparation method and application.

[0009] To achieve the above objectives, the first aspect of the present invention provides a thiol-modified surface-enhanced Raman scattering composite substrate, which comprises a substrate, silver nanowires and gold nanospheres attached to the substrate, and thiols modified on the silver nanowires and gold nanospheres.

[0010] A second aspect of the present invention provides a method for preparing a thiol-modified surface-enhanced Raman scattering composite substrate, the method comprising the following steps:

[0011] (1) attaching silver nanowires and gold nanospheres on the surface of a substrate to obtain an active substrate;

[0012] (2) The active substrate obtained in step (1) is modified with thiol to obtain the thiol-modified surface-enhanced Raman scattering composite substrate.

[0013] The third aspect of the present invention provides the use of the thiol-modified surface-enhanced Raman scattering composite substrate described in the first aspect or the thiol-modified surface-enhanced Raman scattering composite substrate prepared by the method described in the second aspect in the detection of hydrophobic molecules, especially in the detection of polycyclic aromatic hydrocarbons.

[0014] Compared with the prior art, the thiol-modified surface-enhanced Raman scattering composite substrate provided by the present invention combines gold nanospheres with silver nanowires to form a three-dimensional nanostructure of silver nanowires and gold nanospheres (active substrate), effectively increasing the density and intensity of the electromagnetic field enhancement region and improving the detection effect of the SERS (surface-enhanced Raman scattering) substrate. Furthermore, the thiol-modified three-dimensional nanostructure of silver nanowires and gold nanospheres (active substrate) is modified with thiol to obtain the thiol-modified surface-enhanced Raman scattering composite substrate of the present invention, wherein the SH of the thiol can form Ag-S and Au-S bonds with the silver nanowires and gold nanospheres, respectively, and can effectively adsorb polycyclic aromatic hydrocarbons to the surface of the composite substrate through hydrophobic interaction, further improving the detection effect of polycyclic aromatic hydrocarbons. In addition, the present invention also provides a method for preparing the thiol-modified surface-enhanced Raman scattering composite substrate, which is simple and quick to prepare by solution volatilization self-assembly (e.g., drop coating, immersion, etc.), does not involve expensive equipment; the substrate is solid, which is convenient for storage and operation, thereby facilitating further promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 are scanning electron micrographs of different substances attached to the surface of a substrate, wherein (A) is a scanning electron micrograph of silver nanowires attached to the surface of a substrate according to a specific embodiment of the present invention, and (B) is a scanning electron micrograph of silver nanowire-gold nanospheres attached to the surface of a substrate according to a specific embodiment of the present invention;

[0016] Figure 2 The composite substrates prepared in Examples 1-3 are 10 -3 Surface-enhanced Raman signal spectrum obtained by detecting pyrene at mol / L;

[0017] Figure 3 The composite substrates prepared in Examples 1, 4, and 5 are 10 -3 Surface-enhanced Raman signal spectrum obtained by detecting pyrene at mol / L;

[0018] Figure 4 The substrate is modified with different thiol molecules. The composite substrate prepared in Examples 1, 6, and 7 is 10 -3 Surface-enhanced Raman signal spectrum obtained by detecting pyrene at mol / L;

[0019] Figure 5 The composite substrates prepared in Examples 1, 8, and 9 were immersed in the propyl mercaptan solution for different time periods. - 3 Surface-enhanced Raman signal spectrum obtained by detecting pyrene at mol / L;

[0020] Figure 6 This is the surface enhanced Raman signal spectrum obtained by detecting different concentrations of pyrene on the composite substrate prepared in Example 1;

[0021] Figure 7 The 590 cm obtained in test examples 1 and 10-12 -1 The function relationship curve of the intensity of the characteristic peak at and concentration;

[0022] Figure 8 The composite substrates in Comparative Examples 1-3 are 10 -3 Surface-enhanced Raman signal spectrum obtained by detecting pyrene at mol / L. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0024] A first aspect of the present invention provides a thiol-modified surface-enhanced Raman scattering composite substrate, which comprises a substrate, silver nanowires and gold nanospheres attached to the substrate, and thiols modified on the silver nanowires and gold nanospheres.

[0025] According to some embodiments of the present invention, the adhesion rate of the silver nanowires to the substrate can be 50-90%, preferably 70-80%, and the adhesion rate of the gold nanospheres to the silver nanowires can be 50-95%, preferably 70-80%. The "adhesion rate" is calculated based on scanning electron microscope images, with the coverage of the silver nanowires on the substrate and the coverage of the gold nanospheres on the silver nanowires per unit area being calculated.

[0026] According to some embodiments of the present invention, in order to make the prepared composite substrate have better performance, the present invention has certain requirements on the shape and size of nanosilver, wherein the silver nanowires are cylindrical, with a diameter of 10-30 nm, preferably 15-25 nm; and a length of 20-40 μm, preferably 25-35 μm.

[0027] According to some embodiments of the present invention, the content of the silver nanowires may be 0.02-0.21 mg, preferably 0.05-0.12 mg (0.05 mg, 0.06 mg, 0.07 mg, 0.08 mg, 0.09 mg, 0.1 mg, 0.11 mg, 0.12 mg or any value therebetween) per square centimeter of the substrate.

[0028] According to some embodiments of the present invention, in order to make the prepared composite substrate have better performance, the present invention has certain requirements on the diameter of the gold nanospheres. The diameter of the gold nanospheres can be 10-40 nm, preferably 20-30 nm.

[0029] According to some embodiments of the present invention, the content of the gold nanospheres can be 0.006-0.125 mg, preferably 0.024-0.06 mg (0.024 mg, 0.025 mg, 0.026 mg, 0.027 mg, 0.028 mg, 0.029 mg, 0.03 mg, 0.04 mg, 0.05 mg, 0.06 mg or any value in between) per square centimeter of the substrate.

[0030] According to some embodiments of the present invention, the thiol is a linear alkyl thiol, preferably selected from C3-C12 thiols (propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, heptyl mercaptan, ..., dodecanethiol), more preferably selected from C3-C6 thiols.

[0031] The present invention has no special requirements on the type of substrate, and a conventional surface-enhanced Raman substrate of the present invention can be used. For example, the substrate can be selected from a glass substrate or a semiconductor substrate.

[0032] In the present invention, there is no special requirement for the thickness of the substrate, as long as it can meet the requirements of the present invention. In order to obtain better effects, the thickness of the substrate can be 0.2-2 cm, preferably 0.5-1 cm.

[0033] According to a particularly preferred embodiment, the silver nanowires have an adhesion rate of 70-75% to the substrate, and the gold nanospheres have an adhesion rate of 75-80% to the silver nanowires. The silver nanowires are cylindrical, with a diameter of 25-35 nm and a length of 18-22 μm. The silver nanowire content per square centimeter of substrate is 0.07-0.1 mg. The gold nanospheres have a diameter of 22-28 nm and a content of 0.03-0.05 mg per square centimeter of substrate. The thiol is a linear alkyl thiol, a C3-C5 thiol.

[0034] A second aspect of the present invention provides a method for preparing a thiol-modified surface-enhanced Raman scattering composite substrate, the method comprising the following steps:

[0035] (1) attaching silver nanowires and gold nanospheres on the surface of a substrate to obtain an active substrate;

[0036] (2) The active substrate obtained in step (1) is modified with thiol to obtain the thiol-modified surface-enhanced Raman scattering composite substrate.

[0037] According to some embodiments of the present invention, in step (1), the silver nanowires and gold nanospheres are attached to the surface of the substrate by sequentially attaching the silver nanowires and the gold nanospheres to the surface of the substrate.

[0038] In the present invention, there is no particular limitation on the method of attaching the silver nanowires and gold nanospheres, and they can be coated in the form of a sol.

[0039] Preferably, the silver nanowires are attached by first drop coating using silver nanowire sol.

[0040] Preferably, the gold nanospheres are attached by performing a second drop coating using a gold nanosphere sol.

[0041] According to some embodiments of the present invention, the concentration of the silver nanowire sol may be 0.5-3 mg / mL, preferably 1-2 mg / mL.

[0042] According to some embodiments of the present invention, the silver nanowires are cylindrical, with a diameter of 10-30 nm, preferably 15-25 nm; and a length of 20-40 μm, preferably 25-35 μm.

[0043] In the present invention, the silver nanowire sol can be prepared by the following steps:

[0044] In the presence of a first solvent, polyvinyl pyrrolidone is brought into contact with silver nitrate to obtain a mixed solution, and the mixed solution is sealed and heated to obtain a suspension; and then centrifuged to obtain.

[0045] Wherein, the first solvent is water.

[0046] The contact conditions may include: a temperature of 20-40°C, preferably 25-35°C; a time of 10-50 min, preferably 20-40 min; a rotation speed of 200-500 rpm, preferably 300-400 rpm; wherein, the amount of polyvinyl pyrrolidone per gram of silver nitrate is 5-30 g, preferably 15-20 g; and the amount of the first solvent per milligram of silver nitrate is 0.5-5 mL, preferably 1-3 mL.

[0047] The sealing heat treatment conditions may include: a temperature of 120-200° C., preferably 150-180° C.; and a time of 2-10 hours, preferably 5-8 hours.

[0048] The centrifugation conditions may include: a rotation speed of 2000-6000 rpm, preferably 3000-5000 rpm, and a time of 2-20 min, preferably 5-10 min. The centrifugation step may be repeated 2-5 times.

[0049] In the present invention, the silver nanowire sol is preferably prepared according to the following steps:

[0050] The first solvent is mixed with polyvinyl pyrrolidone and stirred at room temperature (25-30°C) for 20-40 minutes to obtain a polyvinyl pyrrolidone solution; AgNO3 is then added to the polyvinyl pyrrolidone solution and stirred at 300-400 rpm for 5-15 minutes to obtain a mixed solution; the mixed solution is then sealed and heated at 150-180°C for 5-8 hours to obtain a suspension containing nanosilver; and the suspension is finally centrifuged at 3500-4500 rpm for 3-8 minutes, and the process is repeated 2-5 times to obtain a silver nanowire sol. The first solvent is preferably water.

[0051] According to some embodiments of the present invention, the first drop coating conditions may include: a temperature of 20-100°C, preferably 30-80°C (30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any value therebetween).

[0052] The present invention has no particular limitation on the time of the first drop coating, as long as the solvent of the silver nanowire sol can be completely volatilized and the silver nanowires can be attached to the surface of the substrate.

[0053] In the present invention, the silver nanowires are preferably adsorbed on the surface of the substrate under the action of capillary force and gravity.

[0054] According to some embodiments of the present invention, the amount of the silver nanowire sol is 40-70 μL, preferably 50-60 μL, per square centimeter of the substrate.

[0055] According to some embodiments of the present invention, the amount of silver nanowires used is such that 0.02-0.21 mg of silver nanowires are attached per square centimeter of substrate surface, preferably 0.05-0.12 mg of silver nanowires are attached.

[0056] According to some embodiments of the present invention, the concentration of the gold nanosphere sol may be 0.3-2.5 mg / mL, preferably 0.8-1.5 mg / mL.

[0057] According to some embodiments of the present invention, the diameter of the gold nanospheres may be 10-40 nm, preferably 20-30 nm.

[0058] In the present invention, the gold nanosphere sol can be prepared by the following method: adding sodium citrate to a HAuCl4 solution heated to boiling to react, and centrifuging the reaction solution after it turns purple-red.

[0059] The HAuCl4 solution can be obtained by mixing an aqueous HAuCl4 solution with a second solvent; the concentration of the aqueous HAuCl4 solution is 0.01-0.05 mol / L, preferably 0.02-0.03 mol / L. The amount of the second solvent used per milliliter of the aqueous HAuCl4 solution is 300-1000 mL, preferably 500-700 mL. The second solvent can be water.

[0060] The sodium citrate is preferably added to the boiling HAuCl4 solution in the form of a solution having a concentration of 0.01-0.05 mol / L, preferably 0.02-0.03 mol / L. The amount of the sodium citrate solution used is 2-20 mL, preferably 5-10 mL, per mL of the HAuCl4 aqueous solution.

[0061] In the preparation of the gold nanosphere sol, the reaction temperature is preferably 100° C.; the reaction time is 10-50 min, preferably 20-40 min.

[0062] In the present invention, the preparation of the gold nanosphere sol is preferably prepared according to the following steps:

[0063] An aqueous solution of HAuCl4 was mixed with deionized water and heated in an oil bath at 120-150°C until the system solution boiled. After that, it was mixed with an aqueous solution of sodium citrate and kept reacting under boiling conditions for 30 minutes until the system solution gradually turned purple-red. The reacted solution was then centrifuged at 3000-4000 rpm for 10-15 minutes to obtain a gold nanosphere sol.

[0064] In the present invention, the first solvent and the second solvent are the same or different.

[0065] According to some embodiments of the present invention, the second drop coating conditions may include: a temperature of 30-100°C, preferably 40-80°C.

[0066] The present invention has no particular limitation on the time of the second drop coating, as long as the solvent of the gold nanosphere sol can be completely evaporated and the gold nanospheres can be attached to the silver nanowires.

[0067] In the present invention, the gold nanospheres are adsorbed on the silver nanowires under the action of capillary force and gravity.

[0068] According to some embodiments of the present invention, the amount of the gold nanosphere sol used is 20-50 μL, preferably 30-40 μL, per square meter of substrate.

[0069] According to some embodiments of the present invention, the gold nanospheres are used in an amount such that 0.06-0.125 mg of gold nanospheres are attached per square centimeter of substrate surface, preferably 0.024-0.06 mg of gold nanospheres are attached.

[0070] According to some embodiments of the present invention, in step (2), the modification is carried out by soaking the active substrate in a thiol solution.

[0071] According to some embodiments of the present invention, the thiol is selected from C3-C12 thiols (propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, heptyl mercaptan, ..., dodecanethiol), preferably selected from C3-C6 thiols.

[0072] In the present invention, before obtaining a thiol-modified surface-enhanced Raman scattering composite substrate, the thiol solution remaining on the active substrate is removed using filter paper. Preferably, after the active substrate is soaked in the thiol solution, it is soaked in a washing solvent (which can be repeated 3-4 times), and then the excess washing solvent and thiol on the surface are removed using filter paper. The washing solvent can be selected from at least one of ethanol, acetone, and ethyl acetate.

[0073] In the present invention, the thiol solution may be at least one of an aqueous solution of thiol, an ethanol solution, an acetone solution, and an ethyl acetate solution, and is preferably an ethanol solution of thiol.

[0074] According to some embodiments of the present invention, the concentration of the thiol solution is 10 -4 -10 -1 mol / L, preferably 10 -3 -10 -2 mol / L.

[0075] According to some embodiments of the present invention, the soaking conditions may include: a temperature of 15-35° C., preferably 20-25° C.; and a time of 0.1-2 h, preferably 0.2-0.8 h.

[0076] In the present invention, the substrate can be selected from a glass substrate or a semiconductor substrate. Preferably, the substrate can be pretreated prior to attachment of the silver nanowires by sequentially cleaning with piranha solution, acetone, ethanol, and deionized water, and then drying (e.g., oven-drying). The amounts of piranha solution, acetone, ethanol, and deionized water used to clean the substrate are not particularly limited, as long as they meet the requirements of the present invention.

[0077] The third aspect of the present invention provides the use of the thiol-modified surface-enhanced Raman scattering composite substrate described in the first aspect or the thiol-modified surface-enhanced Raman scattering composite substrate prepared by the method described in the second aspect in the detection of hydrophobic molecules, especially in the detection of polycyclic aromatic hydrocarbons.

[0078] According to some embodiments of the present invention, the polycyclic aromatic hydrocarbon is selected from at least one of naphthalene, anthracene, phenanthrene, pyrene and benzopyrene; preferably selected from pyrene and / or anthracene.

[0079] According to some embodiments of the present invention, the surface enhanced Raman scattering composite substrate has a detection concentration of polycyclic aromatic hydrocarbons ≥10 -5 mol / L.

[0080] The present invention will be described in detail below through examples.

[0081] In the following examples, the raw materials used are all commercially available products.

[0082] This preparation example is used to illustrate the preparation method of the silver nanowire sol of the present invention.

[0083] Preparation Example A

[0084] To a 250 mL single-necked bottle, 0.3 g of polyvinylpyrrolidone (PVP, M W=55000), 35 mL of deionized water, and stirred at room temperature at 350 rpm for 30 minutes to obtain a clear solution of polyvinyl pyrrolidone; then, 0.017 g of AgNO3 was added to the polyvinyl pyrrolidone solution, and stirred at 350 rpm for 10 minutes to obtain a mixed solution; then, the mixed solution was transferred to a 50 mL hydrothermal autoclave, and sealed at 165°C for 6 hours to obtain a suspension containing nanosilver; the suspension was taken out into a 10 mL centrifuge tube, centrifuged at 4000 rpm for 5 minutes, the supernatant was aspirated, and then deionized water was added, and the mixture was centrifuged again. The centrifugation step was repeated 3 times to remove unreacted reactants and impurities, and finally a silver nanowire (diameter 30 nm, length 20 μm) solution with a concentration of 1.5 mg / mL was obtained.

[0085] This preparation example is used to illustrate the preparation method of the gold nanosphere sol of the present invention.

[0086] Preparation Example B

[0087] To a 250 mL single-necked bottle, HAuCl4 aqueous solution (0.02 mol / L, 0.25 mL) and 150 mL of deionized water were added in sequence, and the solution was heated in an oil bath at 135°C until the system solution boiled. After boiling for 10 min, 2 mL of 0.02 mol / L sodium citrate solution was added, and then the solution was kept warm for 30 min under boiling conditions. The system solution gradually turned purple-red. The reacted solution was then centrifuged at 3500 rpm for 13 min to prepare a gold nanosphere sol with a concentration of 1 mg / mL and a diameter of 25 nm.

[0088] Example 1

[0089] (1) 1cm 2 A glass substrate with a thickness of 5 mm was cleaned with 10 mL of piranha wash solution (a mixed solution of concentrated sulfuric acid and 30% hydrogen peroxide with a volume ratio of 7:3), and then washed with 20 mL of acetone, 20 mL of ethanol and 20 mL of deionized water, respectively, and finally dried with nitrogen to obtain a clean glass substrate. The glass substrate was placed in an oven at 50°C, and 55 uL of 1.5 mg / mL silver nanowire sol was first drop-coated on the surface of the glass substrate. After the solvent in the solution evaporated, a substrate with silver nanowires attached (such as Figure 1 A); then place the substrate with silver nanowires attached on a hot plate at 50°C, and apply 35uL of 1.0mg / mL gold nanosphere sol to the surface of the substrate with silver nanowires attached for the second time, and after the solvent in the solution evaporates, an active substrate (such as Figure 1 B).

[0090] (2) The concentration is 10 -3mol / L ethanol solution of propanethiol, at room temperature, the above active substrate was mixed with 1 mL of 10 -3 mol / L propyl mercaptan ethanol solution for 30 minutes; then the soaked active substrate was taken out, and the propyl mercaptan ethanol solution remaining on the surface of the active substrate was removed with filter paper, and then placed in ethanol and shaken for 2 minutes. After taking it out, the propyl mercaptan and ethanol remaining on the surface of the active substrate were removed with filter paper; then, the active substrate was placed in the ethanol solution and shaken for 2 minutes. The above steps (immersing in ethanol, shaking and removing the propyl mercaptan and ethanol remaining on the surface) were repeated 3 times to remove the propyl mercaptan not adsorbed on the surface of the active substrate, and a thiol-modified surface-enhanced Raman scattering composite substrate was obtained, which was counted as S1 (see Table 1).

[0091] Examples 2-9

[0092] The same method as in Example 1 was followed, except that Examples 2-9 varied the amount of silver nanowire sol, the amount of gold nanosphere sol, the type of thiol, and the immersion time in the thiol solution, respectively, as shown in Table 1. The resulting composite substrates were designated S2-S9 (see Table 2).

[0093] Comparative Example 1

[0094] The process was carried out in the same manner as in Example 1, except that no silver nanowires were attached during the preparation of the composite substrate. The resulting composite substrate was designated DS1 (see Table 2).

[0095] Comparative Example 2

[0096] The process was carried out in the same manner as in Example 1, except that no gold nanospheres were attached during the preparation of the composite substrate. The composite substrate obtained was designated as DS2 (see Table 2).

[0097] Comparative Example 3

[0098] The process was carried out in the same manner as in Example 1, except that no thiol soaking was performed during the preparation of the composite substrate. The composite substrate obtained was designated as DS3 (see Table 2).

[0099] Table 1

[0100]

[0101]

[0102] In Table 2, "Attachment Ratio 1" indicates the coverage of the silver nanowires on the substrate per unit area, calculated based on the scanning electron microscope photograph of the substrate; "Attachment Ratio 2" indicates the coverage of the gold nanospheres on the silver nanowires per unit area, calculated based on the scanning electron microscope photograph of the substrate;

[0103] The content of silver nanowires is equal to the concentration of the silver nanowire sol multiplied by the drop volume; the content of gold nanospheres is equal to the concentration of the gold nanosphere sol multiplied by the drop volume.

[0104] Table 2

[0105]

[0106]

[0107] Test Example 1-9

[0108] The composite substrate obtained in the above embodiment was used to perform surface-enhanced Raman signal detection on polycyclic aromatic hydrocarbons (pyrene).

[0109] Test conditions: The test was performed using a Horiba Xplus confocal Raman microscope (manufacturer: Horiba), with a laser wavelength of 785 nm, a power of 10 mW, a filter transmittance of 1%, an integration time of 20 s, and two integrations.

[0110] Test steps: Add 10 μL of 10 -3 mol / L ethanol solution of pyrene was added dropwise to the surface of the composite substrates S1-S9. After the solution was evaporated, the surface enhanced Raman signal of pyrene was tested to obtain different Raman signal intensities.

[0111] like Figure 2 As shown, the characteristic peaks of pyrene molecules are mainly 401, 590, 1058, 1235, 1403, 1594, and 1623 cm -1 Among them, the 590cm-1 of pyrene obtained by testing on S1, S2 and S3 composite substrates at different silver nanowire contents -1 The intensities of the characteristic peaks at 6732, 3241, and 6672 are respectively. The above results show that S2 has the lowest content of silver nanowires and the weakest Raman signal; as the silver nanowire content in S1 increases, the Raman signal becomes stronger; and as the silver nanowire content in S3 increases further, the thickness increases further, and the surface area exposed to the pyrene molecules remains the same, so the Raman signal remains basically the same.

[0112] like Figure 3 As shown in the figure, the 590 cm-1 pyrene concentrations at different gold nanosphere contents were detected on S1, S4 and S5 composite substrates. -1 The intensities of the characteristic peaks at 6732, 4104, and 6770, respectively, are shown. The results show that S4 has the lowest gold nanosphere content, resulting in a weaker Raman signal. As the gold nanosphere content in S1 increases, the Raman signal strengthens. Furthermore, as the gold nanosphere content in S5 increases further, the surface area in contact with the pyrene molecules remains the same, resulting in a Raman signal intensity roughly comparable to that of S1.

[0113] like Figure 4 As shown, different thiols were modified on the substrate, and the 590 cm-1 pyrene was obtained by testing the composite substrates S1, S6 and S7. -1 The intensities of the characteristic peaks at the 300 nm and 300 nm sites are 6732, 4463, and 2499, respectively. S1 is modified with propanethiol, where the adsorbed pyrene molecules are closest to the substrate, resulting in the strongest signal. S6 is modified with hexanethiol, where the adsorbed pyrene molecules are farther from the substrate, resulting in a weaker signal. S7 is modified with dodecanethiol, where the adsorbed pyrene molecules are even farther from the substrate, resulting in the weakest signal.

[0114] like Figure 5 As shown, in the 10 -3 The 590cm-1 pyrene concentrations obtained by immersing the composite substrates of S1, S8 and S9 in ethanol solution of 10 mol / L for different time periods were -1 The intensities of the characteristic peaks at 6732, 3638, and 6702 are respectively. Among them, the immersion time in S8 is relatively short, the number of propanethiol molecules adsorbed on the substrate is small, the adsorption capacity for pyrene is weak, the number of pyrene molecules adsorbed to the substrate is small, and the Raman signal is weak; in S1, the immersion time increases, the number of propanethiol molecules adsorbed on the substrate increases, the adsorption capacity for pyrene is enhanced, the number of pyrene molecules adsorbed to the substrate increases, and the Raman signal is enhanced; in S9, the immersion time is further increased, but the number of propanethiol on the substrate is basically saturated at 30 minutes, and increasing the time cannot increase the density of propanethiol on the substrate. The Raman signal is basically consistent with S1.

[0115] From the above experiments, we can see that S1 is the substrate with the greatest Raman signal enhancement ability.

[0116] Test Example 10-12

[0117] The test was carried out in the same manner as in Test Example 1, except that the concentration of the ethanol solution of pyrene was changed (10 -5 , 10 -4 , 10 - 2 mol / L), and the Raman signal intensity was obtained as Figure 6 shown.

[0118] from Figure 6 It can be seen from the intensity of the characteristic peak that as the concentration gradually decreases, the intensity of the characteristic peak also gradually decreases. -5 Qualitative detection of pyrene molecules at a concentration of 1 mol / L.

[0119] The 590 cm obtained in test examples 1 and 10-12 -1 The intensity of the characteristic peak at is the ordinate, and the logarithm of the concentration is the abscissa, and the functional relationship is obtained. Figure 7 It can be seen that 590cm-1 The logarithm of the intensity and concentration of the characteristic peak at 590 cm-1 shows a good quadratic function relationship. Based on this mathematical relationship, the peak at 590 cm-1 was measured. -1 After measuring the intensity of the characteristic peak, the concentration of the solution can be calculated, thereby achieving quantitative detection of pyrene molecules.

[0120] Therefore, the relationship between the intensity of the obtained Raman signal peak and the concentration of polycyclic aromatic hydrocarbons can achieve quantitative detection of polycyclic aromatic hydrocarbon molecules.

[0121] Comparative Test Examples D1-D3

[0122] The test was carried out in the same manner as in Test Example 1, except that the ethanol solution of pyrene was added dropwise to the composite substrate prepared in Comparative Examples 1-3. After the solution evaporated, the surface enhanced Raman signal of pyrene was measured to obtain the Raman signal intensity. Figure 8 , D1, D2, and D3 are 2497, 3070, and 2156 respectively.

[0123] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. Application of a thiol-modified surface-enhanced Raman scattering composite substrate in detecting pyrene, characterized in that: The composite substrate comprises a substrate, silver nanowires and gold nanospheres attached to the substrate, and propanethiol modified on the silver nanowires and the gold nanospheres; The silver nanowires are cylindrical, with a diameter of 10-30 nm and a length of 20-40 μm; the diameter of the gold nanospheres is 20-30 nm; the adhesion rate of the silver nanowires to the substrate is 70-90%; the adhesion rate of the gold nanospheres to the silver nanowires is 70-95%; The preparation method of the thiol-modified surface-enhanced Raman scattering composite substrate comprises the following steps: (1) attaching silver nanowires and gold nanospheres on the surface of a substrate to obtain an active substrate; (2) Soaking the active substrate in a propylthiol solution to obtain the propylthiol-modified surface-enhanced Raman scattering composite substrate; the soaking conditions include: a temperature of 15-35° C.; and a time of 30 min-2 h.

2. The use according to claim 1, wherein The adhesion rate of the silver nanowires to the substrate is 70-80%; the adhesion rate of the gold nanospheres to the silver nanowires is 70-80%.

3. The use according to claim 1, wherein: The content of the silver nanowires is 0.02-0.21 mg relative to per square centimeter of the substrate.

4. The use according to claim 1, wherein The silver nanowires are cylindrical, with a diameter of 15-25 nm and a length of 25-35 μm; And / or, the content of the silver nanowires is 0.05-0.12 mg per square centimeter of the substrate.

5. The use according to claim 1, wherein The content of the gold nanospheres is 0.006-0.125 mg relative to per square centimeter of the substrate.

6. The use according to claim 1, wherein: The content of the gold nanospheres is 0.024-0.06 mg relative to per square centimeter of the substrate.

7. The use according to claim 1, wherein: The substrate is selected from a glass substrate or a semiconductor substrate.

8. The use according to claim 1, wherein: The surface enhanced Raman scattering composite substrate has a detection concentration of pyrene of ≥10 -5 mol / L.

9. The use according to claim 1, wherein: In step (1), the silver nanowires and gold nanospheres are attached to the surface of the substrate in a manner of sequentially attaching the silver nanowires and gold nanospheres to the surface of the substrate.

10. The use according to claim 1, wherein: The silver nanowires are attached by first drop coating using silver nanowire sol.

11. The use according to claim 1, wherein: The gold nanospheres are attached by using a second drop coating of the gold nanosphere sol.

12. The use according to claim 10, wherein: The concentration of the silver nanowire sol is 0.5-3 mg / mL.

13. The use according to claim 10, wherein: The concentration of the silver nanowire sol is 1-2 mg / mL.

14. The use according to claim 10, wherein: The conditions of the first drop coating include: a temperature of 20-100°C; And / or, the amount of the silver nanowire sol is 40-70 μL per square centimeter of the substrate.

15. The use according to claim 10, wherein: The conditions of the first drop coating include: a temperature of 30-80°C; And / or, the amount of the silver nanowire sol is 50-60 μL per square centimeter of the substrate.

16. The use according to claim 11, wherein: The concentration of the gold nanosphere sol is 0.3-2.5 mg / mL.

17. The use according to claim 11, wherein: The concentration of the gold nanosphere sol is 0.8-1.5 mg / mL.

18. The use according to claim 11, wherein: The second drop coating conditions include: a temperature of 30-100°C; And / or, the amount of the gold nanosphere sol used is 20-50 μL per square meter of substrate.

19. The use according to claim 11, wherein: The conditions of the second drop coating include: a temperature of 40-80°C; And / or, the amount of the gold nanosphere sol used is 30-40 μL per square meter of substrate.

20. The use according to claim 1, wherein: The concentration of the propyl mercaptan solution is 10 -4 -10 -1 mol / L.

21. The use according to claim 1, wherein: The concentration of the propyl mercaptan solution is 10 -3 -10 -2 mol / L; And / or, the soaking conditions include: temperature of 20-25° C.; time of 0.5-0.8 h.

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