High-activity surface enhanced Raman scattering substrate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of surface enhanced Raman spectroscopy, and particularly relates to a high-activity surface enhanced Raman scattering substrate as well as a preparation method and application thereof. Comprising the following steps: by utilizing a three-phase liquid-liquid interface self-assembly method, adding dichloromethane into an AuNPs dispersion liquid, uniformly mixing, adding a halide salt solution, uniformly mixing to form a mixed solution, then adding normal hexane into the mixed solution, standing, performing interface self-assembly until a gold nano-film is formed on a liquid surface, fishing out the gold nano-film, and drying to obtain the gold nano-film. The high-activity surface enhanced Raman scattering substrate is obtained. According to the method, the halide salt solution is innovatively introduced in the self-assembly process of the AuNPs, so that the assembly arrangement mode of the AuNPs is remarkably changed, the AuNPs are arranged more tightly, local surface plasma resonance coupling is enhanced, more hot spot areas are generated in a unit area, and the sensitivity of the self-assembly nano array SERS substrate is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of surface enhanced Raman spectroscopy, and in particular relates to a high-activity surface enhanced Raman scattering substrate and a preparation method and application thereof. Background Art

[0002] Food hazard detection is a key link in ensuring food safety, and its requirements are strict and comprehensive. The detection scope is wide, covering chemical hazards such as pesticide residues, veterinary drug residues, heavy metals and food additive abuse, biological hazards including pathogenic bacteria, viruses and parasites, and physical hazards such as plastics. In order to deal with such complex and diverse food hazards, the detection method must have high sensitivity, good specificity, high accuracy and rapidity, and should also have multi-residue detection capabilities. At present, commonly used food hazard detection methods include high performance liquid chromatography (HPLC), gas chromatography (GC), mass spectrometry (MS), enzyme-linked immunosorbent assay (ELISA) and microbial detection methods. Although these methods have their own advantages, they also have limitations such as complex operation, long time consumption, the need for professional personnel and expensive equipment.

[0003] In recent years, surface enhanced Raman scattering (SERS), as a highly sensitive fingerprint vibrational spectroscopy technology, has great application potential in the field of food hazard detection. SERS can provide detailed specific molecular structure information for various compounds and biological species, and has significant advantages such as high sensitivity, rapid detection and label-free detection. It has shown broad application prospects in many fields such as analytical chemistry, food science and biology. However, ordinary Raman spectroscopy has low sensitivity when excited by laser, and this defect seriously limits its in-depth application in the detection of low-concentration food hazard residues. In order to give full play to the potential of Raman spectroscopy technology in the rapid detection of food hazard residues, SERS substrate construction is the key to realizing surface enhanced Raman scattering.

[0004] The methods for constructing SERS substrates include liquid-liquid interface self-assembly, flexible substrate, solid substrate, liquid substrate, etc. Compared with other assembly methods, liquid-liquid interface self-assembly has the advantages of being able to precisely control the morphology, lateral spacing and uniformity of nanoparticles, and can form large-area nanoarrays. It has been used to construct a variety of surface-enhanced Raman scattering substrates for rapid detection of residues of various food hazards. Although the liquid-liquid interface self-assembly method has certain advantages in constructing SERS substrates, the controllability of its liquid-liquid interface self-assembly process is obviously insufficient. For example, it is difficult to precisely control the spacing between nanoparticles, and the hot spot area per unit area is poor. The detection limit of the constructed SERS substrate is relatively high, and the sensitivity is obviously insufficient when detecting trace target molecules. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a highly active surface enhanced Raman scattering substrate and a preparation method and application thereof. The introduction of a halide solution during the liquid-liquid interface self-assembly process changes the assembly arrangement of AuNPs, promotes the formation of a tightly arranged gold film structure, thereby reducing the distance between AuNPs, enhancing the localized surface plasmon resonance coupling, and significantly increasing the number of SERS hotspot areas, thereby greatly improving the sensitivity of the liquid-liquid interface self-assembled SERS substrate using traditional AuNPs.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The first object of the present invention is to provide a method for preparing a highly active surface-enhanced Raman scattering substrate, comprising the following steps: Using the three-phase liquid-liquid interface self-assembly method, dichloromethane is added to the AuNPs dispersion and mixed evenly, then a halide solution is added and mixed evenly to form a mixed solution, and then n-hexane is added to the mixed solution, and the interface is allowed to self-assemble until a gold nanofilm is formed on the liquid surface. During the static self-assembly process, the halide solution induces the interface aggregation of AuNPs, promotes the close arrangement of AuNPs, forms a gold nanofilm, and then the gold nanofilm is fished out to obtain a highly active surface enhanced Raman scattering substrate.

[0008] Furthermore, the halide salt solution is an alkali metal halide solution, and the concentration of the alkali metal halide solution is 0.01 mol / L to 2 mol / L.

[0009] Furthermore, the alkali metal halide is at least one of sodium chloride, potassium chloride and potassium bromide.

[0010] Furthermore, the volume ratio of the AuNPs dispersion to dichloromethane is 0.5 to 3:2.

[0011] Furthermore, the volume ratio of the dichloromethane, the halide solution and n-hexane is 1.5-2.5:1:1.

[0012] Furthermore, the AuNPs dispersion is formed by mixing AuNPs particles and ethanol in a mass volume ratio of 10 mL: 0.5 mL to 3 mL.

[0013] Furthermore, the preparation method of AuNPs particles comprises the following steps: S1. After mixing the first sodium citrate solution, the first chloroauric acid solution and water, a reduction reaction is performed to obtain an AuNPs seed solution.

[0014] S2. Mixing the AuNPs seed solution, the second sodium citrate solution, the first hydroxylamine hydrochloride solution, the second chloroauric acid solution and water to form an AuNPs intermediate.

[0015] S3, mixing the AuNPs intermediate, the third sodium citrate solution, the second hydroxylamine hydrochloride solution, the third chloroauric acid solution and water to obtain an AuNPs solution, and then washing, concentrating and centrifuging to obtain AuNPs particles.

[0016] Furthermore, the dosage ratio of the first sodium citrate solution to the first chloroauric acid solution is 1-1.32:1, and the dosage ratio of the first sodium citrate to water is 0.010-0.015:1.

[0017] Furthermore, the dosage ratio of the first sodium citrate and water is 0.010-0.015:1, the dosage ratio of the AuNPs seed solution, the second sodium citrate solution, the first hydroxylamine hydrochloride solution, the second chloroauric acid solution and water is 30-40:10-20:1:1-2:80-90, and the dosage ratio of the AuNPs intermediate, the third sodium citrate solution, the second hydroxylamine hydrochloride solution, the third chloroauric acid solution and water is 5-15:5-10:1-2:1:55-70.

[0018] Furthermore, the mass concentration of the first sodium citrate solution, the second sodium citrate solution or the third sodium citrate solution is 0.8% to 1.2%, the mass concentration of the first chloroauric acid solution, the second chloroauric acid solution or the third chloroauric acid solution is 0.8% to 1.2%; the concentration of the first hydroxylamine hydrochloride solution and the second hydroxylamine hydrochloride solution is 0.005 mol / L to 0.015 mol / L.

[0019] The second object of the present invention is to provide a highly active surface enhanced Raman scattering substrate, which is obtained by the above preparation method.

[0020] The third object of the present invention is to provide an application of a highly active surface-enhanced Raman scattering substrate in detecting residues of harmful substances in food, wherein the residues of harmful substances include thiabendazole, thiram, acid blue or malachite green.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (2) The present invention provides a method for preparing a highly active surface enhanced Raman scattering substrate, which adopts a three-phase liquid-liquid interface self-assembly method, wherein the three-phase liquids are dichloromethane, a halide solution, and n-hexane in sequence. The present invention innovatively introduces a halide solution into the self-assembly process of AuNPs, regulates the surface charge density of gold nanoparticles through halide-induced self-assembly, and uses van der Waals force to achieve more efficient interface aggregation, significantly changing the assembly arrangement of AuNPs, making them more closely arranged, thereby reducing the distance between AuNPs, thereby prompting AuNPs to form a closely arranged gold nanofilm structure, enhancing localized surface plasmon resonance coupling, and generating more hot spots per unit area, effectively improving the sensitivity of the self-assembled nanoarray SERS substrate. The method is easy to operate and does not require the use of complex and expensive equipment. It can achieve high-throughput preparation of large quantities of high-performance SERS substrates. Compared with the single-layer structure formed by traditional salt-free three-phase interface self-assembly, a dense layered gold film can be formed, which significantly improves the SERS enhancement performance of the substrate. The prepared highly active self-assembled nanoarray SERS substrate has higher sensitivity than the existing self-assembled nanoarray SERS substrate.

[0022] (2) The SERS substrate prepared by the innovative process of the present invention exhibits excellent versatility and can achieve high-sensitivity detection of pesticides, veterinary drugs and pigments, effectively improving the SERS detection of target molecules with higher sensitivity. Compared with the traditional detection method based on chromatography and mass spectrometry, the detection speed of the present invention is faster and easier to operate. It can achieve rapid on-site detection through handheld Raman spectroscopy, which shows that the SERS substrate of the present invention has broad application prospects in the detection field of various chemical substances, and provides new ideas and methods for the application of surface enhanced Raman scattering technology in chemical analysis, environmental monitoring, food safety detection and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a distribution diagram of the three-phase solution in the three-phase liquid-liquid interface self-assembly of the present invention.

[0024] Figure 2 The microstructure diagram of the SERS substrate prepared in Comparative Example 1 and Example 4 of the present invention is shown in FIG. Figure 2 a in the figure is a scanning electron microscope image of the SERS substrate prepared in comparative example 1, and b is a scanning electron microscope image of the SERS substrate prepared in example 4.

[0025] Figure 3 This is the ultraviolet absorption graph of the SERS substrate prepared in Examples 1 to 5 of the present invention and Comparative Example 1.

[0026] Figure 4The SERS substrate prepared in Comparative Example 1 of the present invention was respectively exposed to 1 mg / L thiabendazole, 1 mg / L thiram, 1 mg / L acid blue, 10 -4 mol / L tetramercaptobenzoic acid and 10 μg / L malachite green Raman spectra.

[0027] Figure 5 The SERS substrate pair 10 prepared in Examples 1 to 5 of the present invention and Comparative Example 1 -4 mol / L detection Raman map of tetramercaptobenzoic acid, Figure 5 a in the figure is the SERS substrate pair 10 prepared in Examples 1 to 5 and Comparative Example 1 of the present invention. -4 mol / L tetramercaptobenzoic acid detection Raman performance comparison diagram, b is the Raman spectrum diagram of Example 4 and Comparative Example 1.

[0028] Figure 6 Raman spectra of the SERS substrate prepared in Example 4 of the present invention at different concentrations of thiabendazole.

[0029] Figure 7 The Raman spectra of the SERS substrate prepared in Example 4 of the present invention at different concentrations of thiram.

[0030] Figure 8 Raman spectra of the SERS substrate prepared in Example 4 of the present invention at different concentrations of acid blue.

[0031] Fig. 9 This is a linear response relationship diagram of the Raman peak intensity of the SERS substrate prepared in Example 4 of the present invention for detecting different concentrations of thiabendazole and the thiabendazole concentration.

[0032] Fig.10 This is a linear response relationship diagram of the Raman peak intensity of the SERS substrate prepared in Example 4 of the present invention for detecting different concentrations of thiram and the concentration of thiram.

[0033] Fig.11 This is a linear response relationship diagram of the Raman peak intensity and acid blue concentration of the SERS substrate prepared in Example 4 of the present invention when detecting different concentrations of acid blue.

[0034] Fig.12 The Raman peak spectra of the SERS substrates prepared in Example 4 of the present invention and Comparative Example 1 detecting 10 μg / L malachite green.

[0035] Fig.13 The Raman spectra comparison of the SERS substrates prepared in Example 7 of the present invention and Comparative Example 1 for detecting thiabendazole, thiram, acid blue and malachite green are shown in FIG. Fig.13 A is thiabendazole, B is thiram, C is acid blue, and D is malachite green.

[0036] Fig.14 The Raman spectra comparison of the SERS substrates prepared in Example 8 of the present invention and Comparative Example 1 for detecting thiabendazole, thiram, acid blue and malachite green are shown in FIG. Fig.14 A is thiabendazole, B is thiram, C is acid blue, and D is malachite green. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0039] At present, the liquid-liquid interface self-assembly method has certain advantages in constructing SERS substrates. However, this method still faces many problems that need to be overcome in practical applications. First, the SERS substrate constructed by this method has poor stability and is easily affected by external environmental factors such as temperature and humidity, resulting in damage or deformation of the substrate structure. Secondly, it is difficult to achieve precise control of the uniformity of the substrate, the hot spot area is unevenly distributed, and there are also large differences in surface flatness, which greatly affects the accuracy and reliability of the detection results. Furthermore, the controllability of the liquid-liquid interface self-assembly process is obviously insufficient. Many key parameters, including nanoparticle concentration, interfacial tension, assembly time, etc., are difficult to achieve precise control, especially the precise control of the spacing between nanoparticles is even more difficult to achieve, which greatly reduces the reproducibility of substrate preparation and significantly varies performance between different batches. More seriously, the detection limit of the SERS substrate constructed by this method is relatively high, and the sensitivity is obviously insufficient when detecting trace target molecules. In addition, signal overlap and interference phenomena frequently occur during the detection of complex samples, which seriously interferes with the accurate identification and quantitative analysis of target molecules. Based on the above problems, the present invention provides a method for preparing a highly active surface enhanced Raman scattering substrate to solve the problem of low sensitivity of the liquid-liquid interface self-assembly method in constructing a SERS substrate, comprising the following steps:

[0040] Using the three-phase liquid-liquid interface self-assembly method, dichloromethane is added to the AuNPs dispersion and mixed evenly, and then a halide solution is added and mixed evenly to form a mixed solution. Then, n-hexane is added to the mixed solution, and the interface is allowed to self-assemble until a gold nanofilm is formed on the liquid surface. When the gold film is prepared using the three-phase liquid-liquid interface self-assembly method, the distribution diagram of the three-phase solution is as follows: Figure 1 As shown, during the static self-assembly process, the halide solution induces the interface aggregation of AuNPs, promotes the close arrangement of AuNPs, forms a gold nanofilm, and then the gold nanofilm is fished out to obtain a highly active surface-enhanced Raman scattering substrate.

[0041] The present invention provides a method for preparing a highly active surface enhanced Raman scattering substrate, which adopts a three-phase liquid-liquid interface self-assembly method, wherein the three-phase liquids are dichloromethane, a halide solution, and n-hexane in sequence. The present invention innovatively introduces a halide solution into the self-assembly process of nanogold (AuNPs), and utilizes a salt-induced method to assist the self-assembly of nanogold, thereby forming a tightly arranged gold particle film. More specifically, a halide solution is introduced during the self-assembly process of AuNPs, the surface charge density of gold nanoparticles is regulated by halide-induced self-assembly, and more efficient interface aggregation is achieved by utilizing van der Waals forces, which significantly changes the assembly arrangement of AuNPs, making them more closely arranged, thereby reducing the distance between AuNPs, thereby prompting AuNPs to form a closely arranged gold nanofilm structure, enhancing local surface plasmon resonance coupling, and generating more hot spots per unit area, effectively improving the sensitivity of the self-assembled nanoarray SERS substrate. The method is easy to operate, does not require the use of complex and expensive equipment, and can achieve high-throughput preparation of large quantities of high-performance SERS substrates. Compared with the single-layer structure formed by traditional salt-free three-phase interface self-assembly, a dense layered gold film can be formed, which significantly improves the SERS enhancement performance of the substrate. The prepared high-activity self-assembled nanoarray SERS substrate has higher sensitivity than the existing self-assembled nanoarray SERS substrate.

[0042] In a specific embodiment, the halide solution is an alkali metal halide solution, and the concentration of the alkali metal halide solution is 0.01 mol / L to 2 mol / L. More preferably, the halide solution is a metal halide, and the metal halide is at least one of sodium chloride, potassium chloride, and potassium bromide. In the present invention, metal halides include but are not limited to sodium chloride, potassium chloride, potassium bromide, and a combination of multiple halide salts. The present invention significantly changes the assembly and arrangement of AuNPs by introducing a halide solution, making the arrangement more compact, thereby reducing the distance between AuNPs, enhancing the localized surface plasmon resonance coupling, and generating more hot spots per unit area, effectively improving the sensitivity of the self-assembled nanoarray SERS substrate, but the concentration of the halide solution is too high, causing the gold particles to aggregate before assembly and unable to form a gold film. When the concentration is lower than this range, although a gold nanofilm can be formed, the detection effect of the target object will be reduced.

[0043] In a specific embodiment, the volume ratio of the AuNPs dispersion to dichloromethane is 0.5-3:2. The volume ratio of dichloromethane, halide solution and n-hexane is 1.5-2.5:1:1. It should be noted that the present invention adopts a three-phase liquid-liquid interface self-assembly method, wherein the three-phase liquid is dichloromethane, halide solution and n-hexane in sequence, and the volume ratio of dichloromethane, halide solution and n-hexane affects the stability and formation speed of the interface, thereby affecting the morphology and size of the material, and further affecting the uniformity and density of the gold nanofilm, as well as the thickness and coverage area of ​​the gold film.

[0044] In a specific embodiment, the AuNPs dispersion is formed by mixing AuNPs particles and ethanol in a mass volume ratio of 10 mL: 0.5 mL to 3 mL.

[0045] In a specific embodiment, the method for preparing AuNPs particles comprises the following steps: S1. After mixing the first sodium citrate solution, the first chloroauric acid solution and water, a reduction reaction is performed to obtain an AuNPs seed solution.

[0046] S2. Mixing the AuNPs seed solution, the second sodium citrate solution, the first hydroxylamine hydrochloride solution, the second chloroauric acid solution and water to form an AuNPs intermediate.

[0047] S3, mixing the AuNPs intermediate, the third sodium citrate solution, the second hydroxylamine hydrochloride solution, the third chloroauric acid solution and water to obtain an AuNPs solution, and then washing, concentrating and centrifuging to obtain AuNPs particles.

[0048] In the present invention, the particle size of the AuNPs seed solution is 25 nm to 40 nm, the particle size of the AuNPs intermediate is 60 nm to 80 nm, and the particle size of the AuNPs particles is 100 nm to 200 nm.

[0049] The invention adopts AuNPs seed solution prepared by conventional sodium citrate reduction method, then adds sodium citrate solution, hydroxylamine hydrochloride solution and chloroauric acid solution, reduces gold ions to the surface of AuNPs seeds through the reduction effect of hydroxylamine hydrochloride, promotes the growth of particles, adjusts the reduction rate through the synergistic effect of sodium citrate and hydroxylamine hydrochloride, and uses sodium citrate as a stabilizer to control the growth of particles and prevent aggregation, thereby regulating the particle size of AuNPs particles. In the invention, gold nanofilm is prepared by preparing gold particles with large particle size (100 nm to 200 nm), which is beneficial to improving the sensitivity of self-assembled nanoarray SERS substrate. The gold particles with relatively small particle size, such as 25 nm to 80 nm, will reduce the sensitivity of the self-assembled nanoarray SERS substrate, and the detection effect of the target object will be reduced.

[0050] The concentration and centrifugation method is to add 0.08% to 0.2% sodium dodecyl sulfate and 0.008% to 0.02% Tween 20 to AuNPs of 100 nm to 200 nm, mix thoroughly, and centrifuge at 3000 rpm to 4500 rpm for 5 min to 10 min. The dosage ratio of AuNPs, sodium dodecyl sulfate and Tween 20 is 10:1:1.

[0051] In a specific embodiment, the dosage ratio of the first sodium citrate solution and the first chloroauric acid solution is 1-1.32:1, the dosage ratio of the first sodium citrate and water is 0.010-0.015:1, the dosage ratio of the AuNPs seed solution, the second sodium citrate solution, the first hydroxylamine hydrochloride solution, the second chloroauric acid solution and water is 30-40:10-20:1:1-2:80-90, and the dosage ratio of the AuNPs intermediate, the third sodium citrate solution, the second hydroxylamine hydrochloride solution, the third chloroauric acid solution and water is 5-15:5-10:1-2:1:55-70; the mass concentration of the first sodium citrate solution, the second sodium citrate solution or the third sodium citrate solution is 0.8%-1.2%, the mass concentration of the first chloroauric acid solution, the second chloroauric acid solution or the third chloroauric acid solution is 0.8%-1.2%; the concentration of the first hydroxylamine hydrochloride solution and the second hydroxylamine hydrochloride solution is 0.005 mol / L~0.015mol / L.

[0052] In addition, the present invention also provides a highly active surface enhanced Raman scattering substrate, which is obtained by adopting the above preparation method.

[0053] In addition, the present invention also provides the use of a highly active surface-enhanced Raman scattering substrate in detecting hazardous residues in food, wherein the hazardous residues include thiabendazole, thiram, acid blue or malachite green, etc. The SERS substrate prepared by the present invention through an innovative process exhibits excellent versatility, and can achieve high-sensitivity detection of pesticides, veterinary drugs and pigments, effectively improving the SERS detection of target molecules with higher sensitivity. Compared with traditional detection methods based on chromatography and mass spectrometry, the detection speed of the present invention is faster and easier to operate, and on-site rapid detection can be achieved through handheld Raman spectroscopy, which shows that the SERS substrate of the present invention has broad application prospects in the detection field of various chemical substances, and provides new ideas and methods for the application of surface-enhanced Raman scattering technology in chemical analysis, environmental monitoring, food safety detection and other fields.

[0054] The invention is further described below through specific examples.

[0055] Example 1 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: S1. A method for preparing an AuNPs particle dispersion, comprising the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0056] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0057] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0058] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, the volume ratio of AuNPs solution, sodium dodecyl sulfate and Tween 20 is 10:1:1, mix thoroughly, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0059] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 0.01 mol / L sodium chloride solution and mix thoroughly to form a mixed solution.

[0060] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0061] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0062] Example 2 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0063] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0064] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0065] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, and the volume ratio of AuNPs solution, sodium dodecyl sulfate, and Tween 20 is 10:1:1. After fully mixing, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0066] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 0.05 mol / L sodium chloride solution and mix thoroughly to form a mixed solution.

[0067] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0068] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0069] Example 3 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0070] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0071] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0072] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, and the volume ratio of AuNPs, sodium dodecyl sulfate, and Tween 20 is 10:1:1. After fully mixing, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0073] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 0.1 mol / L sodium chloride solution and mix thoroughly to form a mixed solution.

[0074] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0075] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0076] Example 4 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: S1. A method for preparing an AuNPs particle dispersion, comprising the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0077] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0078] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0079] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, the volume ratio of AuNPs solution, sodium dodecyl sulfate and Tween 20 is 10:1:1, mix thoroughly, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0080] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 0.5 mol / L sodium chloride solution and mix thoroughly to form a mixed solution.

[0081] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0082] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0083] Example 5 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: S1. A method for preparing an AuNPs particle dispersion, comprising the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0084] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0085] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0086] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, the volume ratio of AuNPs solution, sodium dodecyl sulfate and Tween 20 is 10:1:1, mix thoroughly, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0087] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 1 mol / L sodium chloride solution and mix thoroughly to form a mixed solution.

[0088] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0089] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0090] Example 6 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: S1. A method for preparing an AuNPs particle dispersion, comprising the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% and ultrapure water were mixed, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0091] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0092] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0093] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, the volume ratio of AuNPs solution, sodium dodecyl sulfate and Tween 20 is 10:1:1, mix thoroughly, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0094] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 0.5 mol / L potassium chloride solution and mix thoroughly to form a mixed solution.

[0095] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0096] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0097] Example 7 A method for preparing a highly active surface-enhanced Raman scattering substrate comprises the following steps: S1. A method for preparing an AuNPs particle dispersion, comprising the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0098] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0099] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0100] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, and the volume ratio of AuNPs solution, sodium dodecyl sulfate, and Tween 20 is 10:1:1. After fully mixing, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0101] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of 0.5 mol / L potassium bromide solution and mix thoroughly to form a mixed solution.

[0102] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0103] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0104] Comparative Example 1 A method for preparing a Raman scattering substrate comprises the following steps: S1. A method for preparing an AuNPs particle dispersion, comprising the following steps: Sodium citrate with a mass percentage concentration of 1%, chloroauric acid with a mass percentage concentration of 1% were mixed with ultrapure water, stirred, and subjected to a reduction reaction to obtain an AuNPs seed solution with a particle size of 30 nm.

[0105] The AuNPs seed solution with a particle size of 30 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 33:1.6:14:1:83 and stirred to obtain an AuNPs intermediate with a particle size of 70 nm.

[0106] The AuNPs intermediate with a particle size of 70 nm, sodium citrate with a mass percentage concentration of 1%, hydroxylamine hydrochloride solution with a concentration of 0.01 mol / L, chloroauric acid with a mass percentage concentration of 1%, and water were mixed in a volume ratio of 10:1:6.25:1.5:62.5 and stirred to obtain a 140 nm AuNPs solution.

[0107] Take an AuNPs solution with a particle size of 140 nm, add 0.1% sodium dodecyl sulfate and 0.01% Tween 20 by mass, the volume ratio of AuNPs solution, sodium dodecyl sulfate and Tween 20 is 10:1:1, mix thoroughly, centrifuge at 4000 rpm for 6 min to obtain AuNPs particles, and add 1.8 mL of anhydrous ethanol to disperse the precipitate to obtain an AuNPs particle dispersion, which is stored for later use.

[0108] S2. Add 2 mL of dichloromethane to the AuNPs particle dispersion prepared in S1 and mix thoroughly, then add 1 mL of ultrapure water and mix thoroughly to form a mixed solution.

[0109] S3. Slowly pour the mixed solution system obtained in S2 into a plastic measuring cup, add 1.5 mL of n-hexane, and allow the interface to self-assemble until a gold nanofilm is formed on the liquid surface.

[0110] S4. Pick up the gold nanofilm obtained in S3 with a silicon wafer and dry it to obtain a SERS substrate.

[0111] Figure 2 The microstructure diagram of the SERS substrate prepared in Example 4 of the present invention and Comparative Example 1, Figure 2 a in FIG. 1 is a scanning electron microscope image of the SERS substrate of comparative example 1, and b is a scanning electron microscope image of the SERS substrate of example 4. Figure 2 As shown, it was observed that compared with the SERS substrate without sodium chloride solution in the control example, the gap between AuNPs in the SERS substrate after adding sodium chloride solution was significantly reduced, thereby enhancing the localized surface plasmon resonance coupling effect, forming more SERS "hotspot" areas, and then improving the SERS enhancement signal of the material, providing strong technical support for high-sensitivity detection.

[0112] The SERS substrates prepared in Examples 1 to 5 and Comparative Example 1 are used to detect hazardous residues in food, including the following steps: the SERS substrates prepared in Examples 1 to 5 and Comparative Example 1 are respectively immersed in 500 μL of target solution, and SERS detection can be performed after drying. The target solution includes 1 mg / L thiabendazole, 1 mg / L thiram, 1 mg / L acid blue, 10 -4 mol / L tetramercaptobenzoic acid (MBA), 10 μg / L malachite green. The results are as follows:

[0113] Figure 3 The ultraviolet absorption diagram of the SERS substrate prepared in Examples 1 to 5 of the present invention and Comparative Example 1 is shown in FIG. Figure 3 As shown, the SERS substrates prepared in Examples 1 to 5 and Comparative Example 1 all have gold nanofilms, so their ultraviolet absorption overlaps and all have obvious ultraviolet absorption peaks at 596 nm.

[0114] Figure 4 The SERS substrate prepared in Comparative Example 1 of the present invention was respectively exposed to 1 mg / L thiabendazole, 1 mg / L thiram, 1 mg / L acid blue, 10 -4 Raman spectra of 10 μg / L tetramercaptobenzoic acid and 10 μg / L malachite green. Figure 4 As shown in the Raman spectrum, at 1008 cm -1 , 1375 cm -1 , 1216 cm -1 , 1074 cm -1 and 1615 cm -1 The Raman characteristic peaks of thiabendazole, thiram, acid blue, tetramercaptobenzoic acid and malachite green can be observed at the positions respectively.

[0115] Figure 5 The SERS substrate pair 10 prepared in Examples 1 to 5 of the present invention and Comparative Example 1 -4 mol / L detection Raman map of tetramercaptobenzoic acid, Figure 5 a in the figure is the SERS substrate pair 10 prepared in Examples 1 to 5 and Comparative Example 1 of the present invention. -4 mol / L tetramercaptobenzoic acid detection Raman performance comparison chart, b is the Raman spectrum of Example 4 and Comparative Example 1. Figure 5 As shown in Figure a, with the gradual increase of sodium chloride concentration, the Raman signal of tetramercaptobenzoic acid detected by the self-assembled SERS substrate shows an increasing trend. When the added concentration of sodium chloride is 0.5 mol / L, the Raman signal reaches the maximum value, as shown in Figure 2. Figure 5As shown in b, compared with the substrate without adding sodium chloride (Comparative Example 1), the Raman signal enhancement ratio of tetramercaptobenzoic acid detected under this condition reached 615.43%.

[0116] In order to illustrate the detection effect of the highly active SERS substrate prepared by the innovative process of the present invention on food hazards, the SERS substrate prepared in Example 4 was used to detect thiabendazole, thiram, acid blue, and malachite green, specifically comprising the following steps: Step 1: accurately weigh thiabendazole, prepare a solution with a concentration of 100 ppm, and finally dilute the concentration to 0.2ppm~10 ppm; accurately weigh thiram, prepare a solution with a concentration of 100 ppm, and finally dilute the concentration to 0.1 ppm~10 ppm. Accurately weigh acid blue, prepare a solution with a concentration of 100 ppm, and finally dilute the concentration to 0.05 ppm~5ppm.

[0117] Step 2, weigh 500 μL of the above-mentioned thiabendazole, thiram and acid blue solutions with different concentration gradients, respectively, and immerse the SERS substrate prepared in Example 4 in the above-mentioned thiabendazole, thiram and acid blue solutions with different concentration gradients, respectively. After 30 minutes, take them out and dry them. Use a handheld Raman spectrometer to detect the Raman signal, with an excitation wavelength of 785 nm, an excitation power of 60 mW, and an excitation time of 2 s. Align the Raman probe to the substrate surface and collect the Raman intensity.

[0118] Thiabendazole 1008 cm -1 、Fumei Shuang 1375 cm -1 、Acid blue 1216 cm -1 The Raman intensity at the position is taken as the ordinate, and the concentration of the target is taken as the abscissa, and the standard curves of thiabendazole, thiram and acid blue are established respectively.

[0119] Figure 6 The Raman spectra of the SERS substrate prepared in Example 4 of the present invention at different concentrations of thiabendazole are shown in FIG. Figure 6 As shown in the figure, in the range of 0.2 ppm to 10 ppm of thiabendazole, as the concentration of the target substance increases, the 1008 cm -1 The intensity of the Raman vibration peak also gradually increases.

[0120] Figure 7 The Raman spectra of the SERS substrate prepared in Example 4 of the present invention at different concentrations of thiram are shown. Figure 7 As shown in the figure, in the range of 0.1 ppm to 10 ppm of thiram concentration, as the concentration of the target substance increases, the peak at 1375 cm -1 The intensity of the Raman vibration peak also gradually increases.

[0121] Figure 8The Raman spectra of the SERS substrate prepared in Example 4 of the present invention at different concentrations of acid blue are shown in FIG. Figure 8 As shown in the figure, in the acid blue concentration range of 0.05 ppm to 5 ppm, as the target concentration increases, the 1216 cm -1 The Raman intensity also gradually increases.

[0122] According to the changes in Raman peak intensity of the SERS substrate prepared in Example 4 for different concentrations of thiabendazole, different concentrations of thiram and different concentrations of acid blue, the linear response relationships between different concentrations of thiabendazole, different concentrations of thiram and different concentrations of acid blue and the Raman absorption spectrum light receiving intensity were constructed respectively, and the fitting curves of Raman spectrum light receiving intensity and thiabendazole concentration, the fitting curves of Raman spectrum light receiving intensity and thiram concentration, and the fitting curves of Raman spectrum light receiving intensity and acid blue were drawn respectively, and the curves with the highest fitting degree were selected as the detection standard curves of thiabendazole, thiram and acid blue, respectively.

[0123] Fig. 9 This is a linear response relationship diagram of the Raman peak intensity and thiabendazole concentration of the SERS substrate prepared in Example 4 of the present invention for different concentrations of thiabendazole. Fig. 9 As shown, the characteristic peak of thiabendazole is 1008 cm -1 The Raman signal intensity at the concentration of 0.2ppm ~ 10ppm shows a good linear relationship, and the linear regression equation y 1 =3.419+0.316x 1 , where y 1 is the logarithm of the Raman signal intensity, x 1 is the logarithm of the concentration of thiabendazole), R 1 2 The detection limit (LOD) was 7.59×10 -3 ppm.

[0124] Fig.10 This is a linear response relationship diagram of the Raman peak intensity and the concentration of thiram detected by the SERS substrate prepared in Example 4 of the present invention. Fig.10 As shown, the characteristic peak of Fumei is 1375 cm -1 The Raman signal intensity at the concentration of 0.1ppm to 10ppm shows a good linear relationship, and the linear regression equation y 2 =3.605+0.490x 2 , where y 2 is the logarithm of the Raman signal intensity, x 2 is the logarithm of the concentration of thiram), R 2 2 is 0.998, and LOD is 9.27×10 -3 ppm.

[0125] Fig.11 The figure is a linear response relationship diagram of the Raman peak intensity and acid blue concentration of the SERS substrate prepared in Example 4 of the present invention for different concentrations of thiram. Fig.11 As shown, the characteristic peak of acid blue is 1216 cm -1 The Raman signal intensity at the concentration of 0.05 ppm to 5 ppm shows a good linear relationship, and the linear regression equation y 3 =462.173+7985.244x 3 , where y 3 is the Raman signal intensity, x 3 is the concentration of thiabendazole), R 3 2 The value of the analytical method is 0.997 and the LOD is 0.039 ppm.

[0126] Fig.12 The Raman peak spectra of the SERS substrate prepared in Example 4 of the present invention and Comparative Example 1 for detecting 10 μg / L malachite green. Fig.12 As shown, compared with Comparative Example 1, the SERS substrate prepared in Example 4 also has a very obvious enhancement effect on the detection of malachite green.

[0127] In summary, the present invention is combined with a portable Raman spectrometer to detect food hazards such as thiabendazole, thiram, acid blue, and malachite green. It has high sensitivity and is easy to operate. It does not require the use of large instruments and equipment, and can achieve rapid on-site detection.

[0128] SERS substrates were prepared using different alkali metal halide solutions, such as Example 6 and Example 7. The SERS substrates prepared in Example 6 and Example 7 were used to detect thiabendazole, thiram, acid blue, and malachite green. The results are as follows.

[0129] The SERS substrate prepared in Example 6 was immersed in 500 μL of 1 mg / L thiabendazole, 1 mg / L thiram, 1 mg / L acid blue, and 10 μg / L malachite green solution, respectively. Fig.13 The Raman spectra comparison of the SERS substrates prepared in Example 6 of the present invention and Comparative Example 1 for detecting thiabendazole, thiram, acid blue and malachite green are shown in FIG. Fig.13 a is thiabendazole, b is thiram, c is acid blue, and d is malachite green. Fig.13 As shown, compared with Comparative Example 1, the SERS substrate prepared in Example 6 also has a very obvious enhancement effect on the detection of thiabendazole, thiram, acid blue and malachite green.

[0130] The SERS substrate prepared in Example 7 was immersed in 500 μL of 1 mg / L thiabendazole, 1 mg / L thiram, 1 mg / L acid blue, and 10 μg / L malachite green solution, respectively. Fig.14 The Raman spectra comparison of the SERS substrates prepared in Example 7 of the present invention and Comparative Example 1 for detecting thiabendazole, thiram, acid blue and malachite green are shown in FIG. Fig.14 a is thiabendazole, b is thiram, c is acid blue, and d is malachite green. Fig.14 As shown, compared with the comparative example, the SERS substrate prepared in Example 7 also has a very obvious enhancement effect on the detection of thiabendazole, thiram, acid blue and malachite green.

[0131] In summary, the present invention proposes an innovative preparation process, which adds a halide solution to the self-assembly process of AuNPs for the first time to construct a self-assembled SERS substrate, significantly changing the assembly arrangement of AuNPs, making them more closely arranged, thereby reducing the distance between AuNPs, enhancing the localized surface plasmon resonance coupling, and having more SERS "hotspot" areas. This improvement also effectively improves the sensitivity of the self-assembled nanoarray SERS substrate to target detection. The method of the present invention is simple to operate, does not require the use of complex and expensive equipment, can achieve high-throughput preparation of large quantities of high-performance SERS substrates, and can be combined with handheld Raman spectroscopy to achieve on-site rapid detection. In addition, the halide solution used in the innovative process of the present invention is a metal halide, and the metal halide includes but is not limited to sodium chloride, potassium chloride, potassium bromide, and a combination of multiple halide salts, which has certain versatility. Moreover, the SERS substrate prepared by the present invention has a wide range of application prospects in the detection field of various food hazards, and provides new ideas and methods for the application of surface enhanced Raman scattering technology in chemical analysis, environmental monitoring, food safety detection and other fields.

[0132] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0133] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a highly active surface-enhanced Raman scattering substrate, characterized in that: The following steps are involved: Using the three-phase liquid-liquid interface self-assembly method, dichloromethane is added to the AuNPs dispersion and mixed evenly, then a halide solution is added and mixed evenly to form a mixed solution, and then n-hexane is added to the mixed solution, and the interface is allowed to self-assemble until a gold nanofilm is formed on the liquid surface. During the static self-assembly process, the halide solution induces the interface aggregation of AuNPs, promotes the close arrangement of AuNPs, forms a gold nanofilm, and then the gold nanofilm is fished out to obtain a highly active surface enhanced Raman scattering substrate.

2. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 1, characterized in that: The halide salt solution is an alkali metal halide solution, and the concentration of the alkali metal halide solution is 0.01 mol / L to 2 mol / L.

3. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 2, characterized in that: The alkali metal halide is at least one of sodium chloride, potassium chloride and potassium bromide.

4. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 1, characterized in that: The volume ratio of the AuNPs dispersion to dichloromethane is 0.5-3:

2.

5. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 1, characterized in that: The volume ratio of the dichloromethane, the halide solution and the normal hexane is 1.5-2.5:1:

1.

6. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 1, characterized in that: The AuNPs dispersion is formed by mixing AuNPs particles and ethanol in a mass volume ratio of 10 mL: 0.5 mL to 3 mL.

7. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 6, characterized in that: The preparation method of AuNPs particles comprises the following steps: The first sodium citrate solution, the first chloroauric acid solution and water are mixed and then subjected to a reduction reaction to obtain an AuNPs seed solution; The AuNPs seed solution, the second sodium citrate solution, the first hydroxylamine hydrochloride solution, the second chloroauric acid solution and water are mixed to form an AuNPs intermediate; The AuNPs intermediate, the third sodium citrate solution, the second hydroxylamine hydrochloride solution, the third chloroauric acid solution and water are mixed to obtain an AuNPs solution, which is then washed, concentrated and centrifuged to obtain AuNPs particles.

8. The method for preparing a highly active surface-enhanced Raman scattering substrate according to claim 7, characterized in that: The dosage ratio of the first sodium citrate solution and the first chloroauric acid solution is 1-1.32:1, and the dosage ratio of the first sodium citrate and water is 0.010-0.015:1; the dosage ratio of the first sodium citrate and water is 0.010-0.015:1, the dosage ratio of the AuNPs seed solution, the second sodium citrate solution, the first hydroxylamine hydrochloride solution, the second chloroauric acid solution and water is 30-40:10-20:1:1-2:80-90, and the dosage ratio of the AuNPs intermediate, the third sodium citrate solution, the second hydroxylamine hydrochloride solution, the third chloroauric acid solution and water is 5-15:5-10:1-2:1:55-70; The mass concentration of the first sodium citrate solution, the second sodium citrate solution or the third sodium citrate solution is 0.8% to 1.2%, the mass concentration of the first chloroauric acid solution, the second chloroauric acid solution or the third chloroauric acid solution is 0.8% to 1.2%; the concentration of the first hydroxylamine hydrochloride solution and the second hydroxylamine hydrochloride solution is 0.005 mol / L to 0.015 mol / L.

9. A highly active surface enhanced Raman scattering substrate, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 8.

10. An application of the highly active surface enhanced Raman scattering substrate according to claim 9 in detecting hazardous residues in food, characterized in that: The hazardous residues are thiabendazole, thiram, acid blue or malachite green.

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