Application of composite SERS (Surface Enhanced Raman Scattering) substrate in nerve poison detection

Abstract

The invention discloses an application of a composite SERS (Surface Enhanced Raman Scattering) substrate in neurotoxic agent detection. The composite SERS substrate is prepared into a detection reagent or detection test paper, the detection reagent or the detection test paper reacts with an MPA solution or atmosphere, and then SERS spectrum detection is carried out. According to the invention, high-sensitivity detection of trace MPA molecules in different matrixes is realized through the coordination effect between unsaturated metal sites and MPA in the composite SERS substrate and the SERS effect of noble metal nanoparticles.

Description

Technical Field

[0001] The present invention belongs to the field of detection and analysis, and particularly relates to the application of a composite SERS substrate in the detection of nerve agents. Background Art

[0002] Nerve agents belong to organophosphorus compounds of cholinesterase inhibitors, which can cause the over-accumulation of acetylcholine by irreversibly inhibiting the action of acetylcholinesterase, and then stimulate receptors, ultimately resulting in characteristic nerve agent poisoning symptoms or even death. Among them, nerve agents such as sarin, soman, tabun, and VX have been used as chemical weapons in wars, military conflicts, and terrorist attacks. It is worth noting that recent terrorist attacks involving nerve agents have shown that human exposure to trace droplets or atmospheres of these agents can lead to poisoning and sudden death. Therefore, there is an urgent need for the country and society to develop highly selective and sensitive nerve agent detection methods to address new challenges in counter-terrorism and public safety. Due to the high toxicity of nerve agents, analogs with chemical structures similar to nerve agents but relatively lower toxicity are often selected to conduct related detection studies. For example, as a sarin analog, methylphosphonic acid (MPA) can be used as a substitute to analyze the use of such nerve agents. Currently, common detection methods for nerve agent analogs include chromatography, mass spectrometry, etc. Although these methods have high sensitivity, they all rely on large-scale instruments and have disadvantages such as complex operation, time-consuming and laborious, and high cost, and cannot be applied to on-site rapid detection; while fluorescence methods applied to on-site rapid detection are easily interfered by the environment.

[0003] Surface-enhanced Raman spectroscopy (SERS) technology can provide rich molecular fingerprint information and has the advantages of high sensitivity and the ability to achieve rapid and non-destructive detection. This spectroscopic technique has very broad application prospects in the field of nerve agent detection. However, the interaction between nerve agent mimics such as MPA and traditional noble metal substrates is very weak, which will result in weak or even no SERS detection signals. Therefore, researchers have developed a variety of approaches and methods to enrich MPA molecules onto the surface of SERS substrates. For example, Stuart Farquharson et al. enhanced the electrostatic interaction between MPA and noble metal substrates by adjusting the pH of the MPA solution to be measured (Chemical and Biological Point Sensors for Homeland Defense, 2004, 5269, 117 - 125); Qian Zhao et al. achieved the capture of trace MPA in solution through chemical modification of gold cone arrays and amide reactions (Journal of Hazardous Materials, 2017, 324, 194 - 202). However, the detection methods based on electrostatic interactions are easily interfered by environmental factors, and the chemical capture strategy is limited by the small variety of modifiers. At the same time, these above methods can only be applied to the detection of MPA in aqueous environments. Summary of the Invention

[0004] In view of the above deficiencies in the prior art, the present invention provides a composite SERS substrate and its application in the detection of nerve agents. The present invention uses the composite SERS substrate to detect nerve agent mimics, which has the characteristics of high sensitivity and rapidity, and can achieve the efficient detection of trace nerve agents in liquid and gas phases.

[0005] The present invention solves the technical problems by adopting the following technical solutions:

[0006] The composite SERS substrate of the present invention is a metal-organic framework material embedded with noble metal nanoparticles, and is obtained by a method including the following steps:

[0007] Disperse 30 - 50 mg of the metal-organic framework material in 30 mL of a noble metal precursor solution with a mass concentration of 1% - 2%. After stirring for 2 hours (the temperature can be selected as room temperature or 45°C according to requirements), add an appropriate amount of reducing agent and react for 15 - 30 minutes. After centrifugation and washing, the composite SERS substrate is obtained.

[0008] The noble metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0009] The metal-organic framework is MIL-101(Cr) or NU-1000.

[0010] The noble metal precursor is chloroauric acid, silver nitrate or silver ammonia solution.

[0011] The reducing agent is sodium citrate, ascorbic acid or glucose.

[0012] Application of the composite SERS substrate of the present invention in the detection of nerve agents.

[0013] Furthermore, a detection reagent or a test strip is prepared from the composite SERS substrate for detecting nerve agents.

[0014] The nerve agents include one or more of sarin, soman, tabun, VX, etc.

[0015] The nerve agents include liquid nerve agents and gaseous nerve agents.

[0016] When detecting nerve agents in the present invention, methylphosphonic acid (MPA), a sarin mimic, is used.

[0017] The specific operation is carried out according to the following steps:

[0018] Detection of MPA solution: Disperse the composite SERS substrate in an aqueous solution (the solution concentration can be adjusted according to requirements, generally controlled at 0.1 mg / mL - 10 mg / mL), add a trace amount of MPA to the solution, and oscillate and react at room temperature for 30 - 180 minutes to obtain a sample to be tested; take 20 μL of the sample to be tested on a clean silicon wafer for SERS spectrum detection.

[0019] Detection of MPA atmosphere: Assemble the composite SERS substrate onto a filter paper by filtration, and let it dry naturally to obtain a test strip; place the MPA solution prepared directly with a solvent or extracted from different matrices at the bottom of a centrifuge tube and seal it. After placing the prepared test strip in the sealed centrifuge tube for 5 - 120 minutes, perform SERS spectrum detection.

[0020] The solvent is an organic solvent such as methanol or ethanol that can cause the co-volatilization phenomenon of MPA molecules.

[0021] The matrix is clothing, leaves or soil.

[0022] The present invention realizes the highly sensitive detection of trace MPA molecules in different matrices through the coordination interaction between the unsaturated metal sites in the composite SERS substrate and MPA and the SERS effect of noble metal nanoparticles.

[0023] Compared with the existing technology, the present invention has the following outstanding advantages and technical effects:

[0024] 1. The composite SERS substrate used in the present invention has both coordination recognition and SERS detection functions, and can be used for the highly sensitive detection of trace nerve agent mimics.

[0025] 2. The use of the composite SERS substrate of the present invention is not only applicable to the detection in liquid phase environment, but also applicable to the detection in gas phase environment.

[0026] 3. The present invention can achieve the efficient detection of trace nerve agent mimics in different matrices, laying a foundation for the widespread application of SERS technology in the real-time and rapid detection of nerve agents. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the method for detecting nerve agent mimics by using the composite SERS substrate in the present invention.

[0028] Figure 2 It is the SERS spectrum of the nerve agent mimic MPA solution detected in Example 1. The wavelength of the excitation light source for SERS spectrum detection is 785 nm. Figure 2 The Raman shift at 759 cm -1 is the vibration peak of the C-P bond in the MPA molecule. After normalizing with the internal standard peak at 1603 cm -1 for all spectra, the intensity of its signal increases with the increase of the MPA concentration. Therefore, from the detected SERS signal of MPA, it shows that the prepared AuNPs / MIL-101(Cr) detection reagent can coordinate and recognize and detect trace MPA molecules in the solution. Figure 2 b is the linear relationship diagram established by this method (linear regression equation: y = 0.1234x + 1.0087, correlation coefficient R 2 = 0.9814), and the detection limit is 10 ppb.

[0029] Figure 3 It is the SERS spectrum of the nerve agent mimic MPA atmosphere detected in Example 2. The wavelength of the excitation light source for SERS spectrum detection is 785 nm. After normalizing with the internal standard peak at 1603 cm -1 for all spectra, the intensity of the signal at 759 cm -1 increases with the increase of time. Therefore, from the detected SERS signal of MPA, it shows that the prepared AuNPs / MIL-101(Cr) test paper can coordinate and recognize and detect trace MPA molecules in the atmosphere.

[0030] Figure 4 It is the SERS spectrum of detecting trace nerve agent mimic MPA in different matrices in Example 5. The wavelength of the excitation light source for SERS spectrum detection is 785 nm. Among them, Figure 4 the matrix of a is clothes, Figure 4 the matrix of b is leaves, Figure 4The matrix of c is soil. The results show that the AgNPs / NU-1000 test strip can be used to efficiently detect trace amounts of the nerve agent mimic MPA in different matrices. Detailed implementation mode

[0031] The technical solution of the present invention is further analyzed and described below through specific examples.

[0032] Example 1:

[0033] In this example, AuNPs / MIL-101(Cr) is used as a composite SERS substrate to describe the method for detecting the nerve agent mimic MPA in solution using AuNPs / MIL-101(Cr).

[0034] (1) Preparation of MIL-101(Cr)

[0035] Dissolve 0.400 g of Cr(NO3)3·9H2O and 0.166 g of terephthalic acid ultrasonically in 4.8 mL of ultrapure water, add 67.4 μL of concentrated nitric acid, and then transfer it to a 50 mL stainless steel autoclave with a polytetrafluoroethylene inner liner. React at 220 °C for 8 h; after cooling to room temperature, wash the obtained product 3 times with ultrapure water, N,N-dimethylformamide, and absolute ethanol respectively; finally, dry the product in vacuo at 120 °C for 2 h to obtain MIL-101(Cr).

[0036] (2) Preparation of AuNPs / MIL-101(Cr)

[0037] Disperse 50 mg of MIL-101(Cr) in 30 mL of 0.1% chloroauric acid solution, stir at 45 °C for 2 hours, then heat the solution to the reflux state, quickly add 220 μL of 10% sodium citrate solution, and after reacting for 30 minutes, cool it naturally, centrifuge and wash it to obtain AuNPs / MIL-101(Cr).

[0038] (3) SERS detection of the nerve agent mimic MPA by the AuNPs / MIL-101(Cr) detection reagent

[0039] Disperse the AuNPs / MIL-101(Cr) obtained in step (2) in ultrapure water (concentration: 0.2 mg / mL). Take 1.8 mL of 0.2 mg / mL AuNPs / MIL-101(Cr) solution, add 200 μL of MPA solutions with different concentrations to it, and after oscillating and reacting at room temperature for 180 minutes, obtain the sample to be detected; take 20 μL of the sample to be detected on a clean silicon wafer for SERS spectrum detection. The detection results are shown in Figure 2 .

[0040] Example 2:

[0041] In this example, AuNPs / MIL-101(Cr) was used as a composite SERS substrate to illustrate the method for detecting the nerve agent simulant MPA in the gas phase using AuNPs / MIL-101(Cr).

[0042] (1) Preparation of MIL-101(Cr)

[0043] In this example, the preparation method of MIL-101(Cr) was the same as that in Example 1.

[0044] (2) Preparation of AuNPs / MIL-101(Cr)

[0045] In this example, the preparation method of AuNPs / MIL-101(Cr) was the same as that in Example 1.

[0046] (3) SERS detection of the nerve agent simulant MPA using an AuNPs / MIL-101(Cr) test strip

[0047] AuNPs / MIL-101(Cr) was assembled onto the filter paper by filtration and allowed to dry naturally to obtain an AuNPs / MIL-101(Cr) test strip; an MPA solution directly prepared with methanol was placed at the bottom of a centrifuge tube and sealed. After the prepared test strip was placed in the sealed centrifuge tube for 5 - 90 minutes, SERS spectra were detected. The detection results are shown in Figure 3 .

[0048] Example 3:

[0049] In this example, AgNPs / NU-1000 was used as a composite SERS substrate to illustrate the method for detecting the nerve agent simulant MPA in solution using AgNPs / NU-1000.

[0050] (1) Preparation of NU-1000

[0051] 98 mg of ZrOCl2·8H2O and 2 g of benzoic acid were ultrasonically dissolved in 8 mL of N,N-dimethylformamide. After heating at 100 °C for 1 hour, it was naturally cooled and 40 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene and 40 μL of trifluoroacetic acid were added. After ultrasonication for 10 minutes, it was transferred to a 50 mL stainless steel autoclave with a polytetrafluoroethylene liner and reacted at 100 °C for 18 hours. After natural cooling, the obtained product was centrifuged, soaked and washed 3 times with N,N-dimethylformamide first, then heat-treated at 100 °C for 18 hours with a mixed solution of N,N-dimethylformamide and hydrochloric acid (8 M), and then washed 3 times in a cycle with N,N-dimethylformamide and acetone. Finally, the product was vacuum dried at 80 °C for 12 h to obtain NU-1000.

[0052] (2)Preparation of AgNPs / NU-1000

[0053] 30 mg of NU-1000 was ultrasonically dispersed in 20 mL of ultrapure water, and the supernatant was removed after centrifugation. Then it was dispersed into the silver ammonia solution (the specific preparation steps were: 100 mg of AgNO3 was dissolved in 50 mL of ultrapure water, and 28 - 30 wt% of ammonia water solution was added until the solution was transparent), and stirred at room temperature for 2 hours. Then 10 mL of 5 mg / mL glucose solution was added to the above solution at one time, and the reaction was continued to stir at room temperature for 15 minutes to obtain AgNPs / NU-1000.

[0054] (3)SERS detection of nerve agent simulant MPA by AgNPs / NU-1000 detection reagent

[0055] The AgNPs / NU-1000 obtained in step (2) was dispersed in ultrapure water (concentration: 0.1 mg / mL). Take 0.9 mL of 0.1 mg / mL AgNPs / NU-1000 solution, add 100 μL of aqueous solution containing MPA to it, and shake and react at room temperature for 180 minutes to obtain the sample to be detected. Take 20 μL of the sample to be detected on a clean silicon wafer for SERS spectrum detection.

[0056] Example 4:

[0057] In this example, AgNPs / NU-1000 was used as a composite SERS substrate to elaborate on the method for detecting nerve agent simulant MPA in the gas phase by AgNPs / NU-1000.

[0058] (1)Preparation of NU-1000

[0059] The preparation method of NU-1000 in this example was the same as that in Example 3.

[0060] (2)Preparation of AgNPs / NU-1000

[0061] In this example, the preparation method of AgNPs / NU-1000 is the same as that in Example 3.

[0062] (3)SERS detection of nerve agent simulant MPA by AgNPs / NU-1000 test strips

[0063] Assemble AgNPs / NU-1000 onto the filter paper by filtration, and let it dry naturally to obtain the AgNPs / NU-1000 test strip; place the MPA solution directly prepared with methanol at the bottom of the centrifuge tube and seal it. After placing the prepared test strip in the sealed centrifuge tube for 5 - 120 minutes, perform SERS spectrum detection.

[0064] Example 5:

[0065] In this example, using AgNPs / NU-1000 as the composite SERS substrate, the detection method of trace nerve agent simulant MPA in different matrices by AgNPs / NU-1000 test strips is described.

[0066] (1)Preparation of NU-1000

[0067] In this example, the preparation method of NU-1000 is the same as that in Example 3.

[0068] (2)Preparation of AgNPs / NU-1000

[0069] In this example, the preparation method of AgNPs / NU-1000 is the same as that in Example 3.

[0070] (3)SERS detection of trace nerve agent simulant MPA in different matrices by AgNPs / NU-1000 test strips

[0071] Assemble AgNPs / NU-1000 onto the filter paper by filtration, and let it dry naturally to obtain the AgNPs / NU-1000 test strip; place the MPA solution extracted from clothes, leaves, soil and lake water with methanol at the bottom of the centrifuge tube and seal it. After placing the prepared test strip in the sealed centrifuge tube for 120 minutes, perform SERS spectrum detection. The detection results are shown in Figure 4 。

[0072] The above embodiments are preferred embodiments of the present invention, rather than limitations thereof; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Application of composite SERS substrate in nerve agent detection, characterized by: Using the composite SERS substrate to prepare a detection reagent or a test paper for detecting nerve agents; The composite SERS substrate is a metal organic framework material embedded with noble metal nanoparticles.

2. The use according to claim 1, characterized in that: The nerve agent includes one or more of sarin, soman, tabun and veix.

3. The use according to claim 1 or 2, characterized in that: The nerve agent includes a liquid nerve agent or a gas nerve agent.

4. The use according to claim 3, characterized in that: The composite SERS substrate was dispersed in an aqueous solution with a concentration controlled at 0.1 mg / mL~10 mg / mL. The stock solution to be tested was added to the above system, and the sample to be tested was obtained after oscillating at room temperature for 30~180 minutes. 20 μL of the sample to be tested was taken for SERS spectrum detection.

5. The use according to claim 3, characterized in that: The composite SERS substrate is assembled onto filter paper by filtering and volatilized naturally to obtain a test paper; the test solution is placed at the bottom of a centrifuge tube and sealed, and the test paper is placed in the sealed centrifuge tube for 5 to 120 minutes before SERS spectrum detection.

6. The use according to claim 4 or 5, characterized in that: There is a linear relationship between the detection signal intensity and the concentration of the nerve agent.

7. The use according to claim 5, characterized in that: The solution to be tested is a solution containing the nerve agent, or a solution containing the nerve agent obtained by extracting the nerve agent from different matrices through a solvent; the solvent of the solution to be tested is an organic solvent that can cause the nerve agent molecules to co-volatilize.

8. The use according to claim 7, characterized in that: The solvent is methanol or ethanol.

9. The use according to claim 7, characterized in that: The substrate includes clothing, leaves or soil.

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