Au TOHs (at) ZIF-67 / PA-6 composite material for high-selectivity detection of mixed pesticide and preparation method of Au TOHs (at) ZIF-67 / PA-6 composite material

Abstract

The invention provides an Au TOHs (at) ZIF-67 / PA-6 composite material for high-selectivity detection of mixed pesticides and a preparation method thereof.The Au TOHs (at) ZIF-67 / PA-6 composite material is successfully obtained by synthesizing a gold trioctahedron (Au TOHs) with a high index surface, loading the gold trioctahedron (Au TOHs) with the high index surface on ZIF-67 to obtain Au TOHs (at) ZIF-67, and soaking the Au TOHs (at) ZIF-67 / PA-6 composite material on a nylon six filter membrane. The Au TOHs (at) ZIF-67 / PA-6 composite material is used as an SERS (Surface Enhanced Raman Scattering) substrate, so that the multifunctionality of substrate adsorption is enhanced, the universality is high, the application range is wide, the selectivity is high, the separation and enrichment efficiency is improved, the SERS detection sensitivity is greatly improved, and high-selectivity detection of mixed pesticides is realized.

Description

Technical Field

[0001] The invention relates to an Au TOHs@ZIF-67 / PA-6 composite material for highly selectively detecting mixed pesticides and a preparation method thereof, and belongs to the technical field of biosensor detection. Background Art

[0002] Currently, pesticide exposure is mainly caused by a mixture of multiple pesticides. Rapid detection of pesticide exposure is an urgent problem to be solved. Currently, most methods for detecting mixed pesticide exposure are: high performance liquid chromatography, liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. Although these technologies have good accuracy and stability, they all have disadvantages such as complex sample pretreatment, long detection time, and bulky instruments, which are not suitable for rapid on-site detection and analysis.

[0003] SERS can solve the problems of the above-mentioned existing detection methods and meet the needs of instant detection. SERS is a spectroscopic method for studying molecular vibrations, which can be used to identify functional groups present in molecules. Therefore, it is a molecular spectral fingerprint identification technology with high sensitivity and high selectivity, and has the characteristics of simple preparation, rapid and non-destructive analysis. It has been regarded as an excellent detection and characterization technology, and meets the needs of instant detection. Its enhancement mechanism is the phenomenon of enhanced Raman scattering intensity caused by the plasma resonance interaction between molecules adsorbed on the surface of metal nanostructures and the metal surface. This metal nanoparticle with SERS enhancement effect is also called a substrate. However, SERS technology still faces the following problems in practical applications: 1) Nanomaterials are not novel and take a long time to prepare. 2) It is difficult to separate molecules, and there are problems with impurity interference caused by solution contact and signal authenticity caused by intermolecular contact.

[0004] Nanostructures with high index surfaces have higher chemical reactivity than traditional nanostructures due to their larger atomic kinks, steps and edge densities. They present stronger local electromagnetic fields, leading to more effective surface enhanced Raman scattering performance and higher sensing sensitivity. They are also easy to prepare and can be prepared in less than ten minutes. However, in actual SERS detection, nanostructures with high index surfaces will produce unnecessary interfering peaks, masking the characteristic peak signals of target molecules, affecting the judgment of effective characteristic information of Raman spectra, and resulting in reduced sensitivity. MOF, also known as porous coordination polymer, is a highly porous crystalline material assembled by metal ions and organic structural units through coordination bonds. It has the characteristics of separation of test substances, enrichment of analytes, and ultra-high porosity. There are many types of MOF materials, among which imidazole metal organic frameworks (ZIFs) are widely used because they have high chemical and thermal stability and simple synthesis methods. Nylon hexafluoroethylene (PA-6) membrane can not only attach a large number of high-index surface nanoparticles to avoid agglomeration, but also separate the substances to be tested. It has the characteristics of high specific surface area and ultra-high porosity. In addition, the existing SERS substrates have poor versatility and are either only used for liquids or solids.

[0005] Therefore, there is an urgent need to develop a new SERS substrate with strong versatility, low cost, simple preparation, short time, high separation and enrichment efficiency, and high SERS detection sensitivity. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides an Au TOHs@ZIF-67 / PA-6 composite material for highly selective detection of mixed pesticides and a preparation method thereof.

[0007] The invention first synthesizes gold trioctahedrons (Au TOHs) with high index faces, then loads the gold trioctahedrons (Au TOHs) with high index faces on ZIF-67 to obtain Au TOH@ZIF-67, and then soaks the Au TOHs@ZIF-67 / PA-6 composite material on a nylon hexafilter to successfully obtain the AuTOHs@ZIF-67 / PA-6 composite material. The Au TOHs@ZIF-67 / PA-6 composite material is used as a SERS substrate, which enhances the versatility of substrate adsorption, has strong versatility, a wide range of applications, and strong selectivity, improves separation and enrichment efficiency, greatly improves SERS detection sensitivity, and realizes highly selective detection of mixed pesticides.

[0008] The present invention is achieved through the following technical solutions:

[0009] The preparation method of the Au TOHs@ZIF-67 / PA-6 flexible composite material for highly selective detection of mixed pesticides comprises the following steps:

[0010] 1) Synthesis of gold trioctahedrons (Au TOHs) by seed-mediated method;

[0011] 2) Au TOHs was centrifuged and added to the ZIF-67 solution under continuous stirring. After stirring, the obtained mixture was centrifuged and redispersed in water to obtain Au TOH@ZIF-67 solution;

[0012] 3) PA-6 was cleaned with alcohol and water under ultrasonic wave, and then immersed in Au TOHs@ZIF-67 solution for reaction, and dried naturally at room temperature to obtain Au TOHs@ZIF-67 / PA-6 composite material.

[0013] The gold trioctahedron described in the present invention is denoted as Au TOHs.

[0014] According to the preferred embodiment of the present invention, in step 1), gold trioctahedron (Au TOHs) is prepared by the following method:

[0015] (1) injecting a freshly prepared ice-cold NaBH4 solution into the mixed solution a, stirring and mixing to obtain a seed solution, and diluting with water to obtain a diluted seed solution;

[0016] (2) According to the final size of AuTOHs, the diluted seed solution is added to the mixed solution b, and the resulting mixture is allowed to stand at 40-50° C. for 5-10 minutes to obtain gold trioctahedrons (Au TOHs).

[0017] Preferably, according to the present invention, in step (1), the mixed solution a is composed of a mixture of a 0.1M hexadecyltrimethylammonium bromide solution, a 0.01M HAuCl4 solution, and a 0.01M H2PtCl6 solution, and the volume ratio of the hexadecyltrimethylammonium bromide solution, the HAuCl4 solution, and the H2PtCl6 solution is 975:15:10.

[0018] Preferably, according to the present invention, in step (1), the concentration of the NaBH4 solution is 0.01 M, and the volume ratio of the NaBH4 solution to the mixed solution a is (8-12): (50-150).

[0019] Preferably, according to the present invention, in step (1), the seed solution is diluted by diluting 20 μL of seed solution into 10 mL of pure water to obtain a diluted seed solution.

[0020] Preferably, according to the present invention, in step (1), the mixed solution b is composed of a mixture of a 25 mM hexadecyltrimethylammonium chloride solution, a 0.01 M HAuCl4 solution, a 0.01 M H2PtCl6 solution and a 0.1 M ascorbic acid solution, and the volume ratio of the hexadecyltrimethylammonium chloride solution, the HAuCl4 solution, the H2PtCl6 solution and the ascorbic acid solution is 100:5:0.05:2.5.

[0021] Preferably according to the present invention, in step (1), the volume ratio of the diluted seed solution to the mixed solution b is 250:10755.

[0022] Preferably according to the present invention, in step 2), the centrifugation of gold trioctahedrons (Au TOHs) is as follows: the AuTOHs obtained in step 1) is dispersed in an aqueous solution, and centrifuged twice at a speed of 7000 rpm, each time for 7 minutes.

[0023] Preferably according to the present invention, in step 2), the ZIF-67 solution is prepared by the following method:

[0024] Dissolve 0.45 g of cobalt nitrate hexahydrate in 3 mL of ultrapure water to obtain a cobalt nitrate hexahydrate solution. Dissolve 5.5 g of dimethylimidazole in 20 mL of ultrapure water. Stir the dimethylimidazole solution at 1000 rpm on a magnetic stirrer. After 1 min, slowly add the cobalt nitrate hexahydrate solution. The solution turns bright purple and is stirred for 6 h.

[0025] Preferably according to the present invention, in step 2), the volume ratio of Au TOHs to ZIF-67 solution after centrifugation is (8-12):1.

[0026] Preferably according to the present invention, in step 2), the stirring time is 4-10 minutes.

[0027] Preferably according to the present invention, in step 2), the centrifugation is performed at 8000 rpm for 10 minutes.

[0028] Preferably, according to the present invention, in step 3), the reaction time of immersing PA-6 in the Au TOH@ZIF-67 solution is 10-20 minutes.

[0029] The Au TOHs@ZIF-67 / PA-6 flexible composite material for highly selective detection of mixed pesticides was prepared by the above method.

[0030] The prepared Au TOHs@ZIF-67 / PA-6 flexible composite material is AuTOHs@ZIF-67 uniformly loaded on nylon hexafilter PA-6, and Au TOHs@ZIF-67 is gold trioctahedral particles uniformly loaded on ZIF-67.

[0031] The above-mentioned Au TOHs@ZIF-67 / PA-6 flexible composite material with high selectivity for detecting mixed pesticides is used to detect pesticides in liquids or pesticides on solid surfaces.

[0032] Preferably according to the present invention, the pesticide is chlorfenapyr or a mixture of chlorfenapyr and other pesticides.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. The present invention loads high-index gold trioctahedrons (Au TOHs) on MOF, and then assembles them into a composite substrate with the separation material PA-6, which greatly improves the SERS detection sensitivity, uses PA-6 / MOF to improve the separation and enrichment efficiency, and achieves highly selective detection of mixed pesticides through pore size adjustment and surface modification.

[0035] 2. Since the nanostructure may be affected by impurity peaks when used in SERS, and the nanostructure with a high index surface has no separation function, the present invention loads the gold trioctahedron (Au TOHs) with a high index surface on ZIF-67. The morphology of ZIF-67 masks the unnecessary interfering impurity peaks generated in the SERS detection of the gold trioctahedron (Au TOHs), enhances the Raman signal, greatly improves the sensitivity, and gives the gold trioctahedron the function of separation and enrichment.

[0036] 3. The substrate of the present invention is simple to prepare and takes a short time, and can be prepared in less than ten minutes. The composite material enhances the versatility of substrate adsorption, improves separation and enrichment efficiency, and greatly improves SERS detection sensitivity.

[0037] 4. The Au TOHs@ZIF-67 prepared in the present invention is a flexible substrate, which can be used to adsorb, separate and enrich pesticides in liquid for SERS detection, and can also be used to wipe solid surfaces for SERS detection. It has strong versatility and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the synthesis route and detection of the Au TOHs@ZIF-67 / PA-6 composite material of the present invention.

[0039] Figure 2 This is a transmission electron microscope image of gold trioctahedron (Au TOH) prepared in Example 1 of the present invention; it shows that AuTOHs has a trioctahedral structure and an average particle size of 77nm.

[0040] Figure 3 This is a scanning electron microscope image of the flexible Au TOHs@ZIF-67 / PA-6 substrate prepared in Example 1 of the present invention; a layer of Au TOHs@ZIF-67 is evenly covered on PA-6.

[0041] Figure 4 The SERS images of the substrate obtained by depositing Au TOHs@ZIF-67 on PA-6 at different deposition times in step (4) of Example 1 of the present invention; it can be seen that a very strong SERS signal can be obtained after deposition for 15 minutes.

[0042] Figure 5This is a comparison of the SERS spectra of the flexible Au TOHs@ZIF-67 / PA-6 substrate obtained in step (5) of Example 1 of the present invention and the substrates of Comparative Examples 1 and 2 detecting 1 ppm of chlorfenapyr. It can be seen that the flexible Au TOHs@ZIF-67 / PA-6 substrate obtained in Example 1 has the highest sensitivity and electric field strength.

[0043] Figure 6 The SERS spectra of the flexible Au TOHs@ZIF-67 / PA-6 substrate obtained in step (5) of Example 1 of the present invention for detecting chlorfenapyr in water, cucumber juice, and on the surface of cucumber show that the detection limit can be as low as 10 ng / mL.

[0044] Figure 7 This is a SERS spectrum diagram of the flexible Au TOHs@ZIF-67 / PA-6 substrate obtained in Example 1 of the present invention for detecting a sample of chlorfenapyr doped with diquat. DETAILED DESCRIPTION

[0045] The features of the present invention are further described below by way of examples, but the present invention is not limited to the following examples.

[0046] Embodiment 1:

[0047] The preparation method of Au TOHs@ZIF-67 / PA-6 flexible composite material for highly selective detection of mixed pesticides is as follows:

[0048] Preparation of gold trioctahedron (Au TOH)

[0049] (1) Preparation of seed solution

[0050] 900 μL of freshly prepared ice-cold NaBH4 solution (0.01 M) was injected into a mixed solution a consisting of 9.75 mL of CTAB (0.1 M), 150 μL of HAuCl4 (0.01 M), and 100 μL of H2PtCl6 solution (0.01 M), and 20 μL of the seed solution was diluted into 10 mL of pure water to obtain a diluted seed solution;

[0051] (2) Preparation of 77 nm AuTOHs

[0052] 250 μL of the diluted seed solution prepared in step (1) was added to a mixed solution b consisting of 10 mL CTAC (25 mM), 500 μL HAuCl4 (0.01 M), 5 μL H2PtCl6 (0.01 M) and 250 μL AA solution (0.1 M). The resulting mixture was allowed to stand at 45° C. for 7 minutes, then centrifuged twice at 7000 rpm for 7 minutes each time, and then redispersed in 1 mL of water to obtain Au TOHs. The transmission electron microscopy image of the obtained Au TOHs is shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that Au TOHs has a trioctahedral structure and an average particle size of 77 nm.

[0053] Preparation of Au TOHs@ZIF-67 solution

[0054] (3) Preparation of ZIF-67 solution

[0055] Dissolve 0.45 g of cobalt nitrate hexahydrate in 3 mL of ultrapure water, and dissolve 5.5 g of dimethylimidazole in 20 mL of ultrapure water. Stir the dimethylimidazole solution at 1000 rpm on a magnetic stirrer. After about 1 min, slowly add the cobalt nitrate hexahydrate solution. The solution turns bright purple. Stir for 6 h to obtain a ZIF-67 solution.

[0056] (4) Preparation of Au TOHs@ZIF-67 solution

[0057] 1 mL Au TOHs was mixed with 100 μL ZIF-67 solution and stirred for 5 minutes, then centrifuged at 8000 rpm for 10 minutes, and then redispersed in 1 ml water to obtain Au TOHs@ZIF-67 solution.

[0058] Flexible substrate preparation

[0059] (5) Preparation of flexible Au TOHs@ZIF-67 / PA-6 substrate

[0060] A piece of PA-6 filter membrane was placed in pure water, ethanol, and pure water respectively, and then ultrasonicated for 3 minutes and then naturally dried: In a culture dish, the Au TOHs@ZIF-67 solution was slowly dripped onto the PA-6 filter membrane using a pipette, and after deposition for 15 minutes, it was taken out and naturally dried to obtain the Au TOHs@ZIF-67 / PA-6 flexible composite material, i.e., the flexible Au TOHs@ZIF-67 / PA-6 substrate.

[0061] SEM images of the flexible Au TOHs@ZIF-67 / PA-6 substrate are shown in Figure 3 As shown in the figure, it can be seen that a layer of Au TOHs@ZIF-67 is evenly covered on PA-6.

[0062] Comparative Example 1

[0063] Preparation of Au NPs@ZIF-67 / PA-6

[0064] (1) Preparation of gold nanoparticles: 1.2 ml HAuCl4 was added to 95 ml water and boiled at 130°C and 1000 rpm, then 1 ml 1% sodium citrate was added and boiled for 30 minutes to obtain gold nanoparticles;

[0065] (2) Preparation of ZIF-67 solution

[0066] Dissolve 0.45 g of cobalt nitrate hexahydrate in 3 mL of ultrapure water, and dissolve 5.5 g of dimethylimidazole in 20 mL of ultrapure water. Stir the dimethylimidazole solution at 1000 rpm on a magnetic stirrer. After about 1 min, slowly add the cobalt nitrate hexahydrate solution. The solution turns bright purple. Stir for 6 h to obtain a ZIF-67 solution.

[0067] (3) 1 mL of gold nanoparticles was mixed with 100 μL of ZIF-67 solution and stirred for 5 minutes, then centrifuged at 8000 rpm for 10 minutes, and then redispersed in 1 ml of water after centrifugation to obtain Au NPs@ZIF-67 solution;

[0068] (4) A piece of PA-6 filter membrane was placed in pure water, ethanol, and pure water respectively, and then ultrasonicated for 3 minutes and then naturally dried: In a culture dish, the Au NPs@ZIF-67 solution was slowly added dropwise to the PA-6 filter membrane using a pipette. After soaking the filter membrane for 15 minutes, it was taken out and naturally dried to obtain the Au NPs@ZIF-67 / PA-6 composite material, i.e., the Au NPs@ZIF-67 / PA-6 substrate.

[0069] Comparative Example 2

[0070] Preparation of AuOh NPs@ZIF-67 / PA-6

[0071] (1) Gold octahedron: 250 μL of 10 mM HAuCl4 .4 H2O aqueous solution and 600μL of ice-cold 10mM NaBH4 were added to 9.4mL of 0.1M CTAB solution, stirred at 600rpm for 3min, and heated in an oven at 30℃ for 2h. For rod growth, 500μL of 10mM HAuCl4, 60μL of freshly prepared 10mM AgNO3 and 80μL of 0.1M AA were added to 10mL of 0.1M CTAB and 24μL of CTAB-capped gold seed solution in sequence. The gold nanorod solution was allowed to stand in an oven at 30℃ for 2 hours, followed by two rounds of centrifugal washing (6511g, 20 minutes). For the second overgrowth of gold nanorods, 500μL of 10mM HAuCl4 and 100μL of 0.1M AA were added to 10mL of 10mM CTAB solution and then gently shaken. After the solution became transparent, 10 mL of washing solution was added to the colorless solution, and the mixture was stored at 50 ° C for 40 minutes and washed twice with deionized water (6511 g, 20 minutes). In order to convert the overgrown gold nanorods into quasi-spherical nanoparticles, 10 mL of washing solution and 180 μL of 10 mM HAuCl4 solution were added to 10 mL of 0.01 M CTAB solution for oxidative etching of gold nanorods. The solution was allowed to stand at 50 ° C for 1 hour. Then, the solution was washed twice (6511 g, 20 minutes) and finally dispersed in 10 mL of CPC solution for storage. For the morphological evolution of quasi-spherical NPs to gold nanooctahedra: 400 μL of 40 mM HAuCl4 and 240 μL of 0.1 M AA solution were added to 80 mL of 0.1 M CPC solution and stirred vigorously for 20 s. After a colorless solution was formed, 2 mL of the CPC dispersed particle solution was added to the mixed solution and allowed to stand at 30°C for 2 hours, and the residual reactant was removed by centrifugation (3663 g, 15 minutes).

[0072] (2) Preparation of ZIF-67 solution

[0073] Dissolve 0.45 g of cobalt nitrate hexahydrate in 3 mL of ultrapure water, and dissolve 5.5 g of dimethylimidazole in 20 mL of ultrapure water. Stir the dimethylimidazole solution at 1000 rpm on a magnetic stirrer. After about 1 min, slowly add the cobalt nitrate hexahydrate solution. The solution turns bright purple. Stir for 6 h to obtain a ZIF-67 solution.

[0074] (3) 1 mL of gold octahedron was mixed with 100 μL of ZIF-67 solution and stirred for 5 minutes, then centrifuged at 8000 rpm for 10 minutes, and then redispersed in 1 ml of water to obtain Au Oh NPs@ZIF-67 solution;

[0075] (4) A piece of PA-6 filter membrane was placed in pure water, ethanol, and pure water respectively, and then ultrasonicated for 3 minutes and then naturally dried: In a culture dish, the Au Oh NPs@ZIF-67 solution was slowly added dropwise to the PA-6 filter membrane using a pipette. After soaking the filter membrane for 15 minutes, it was taken out and naturally dried to obtain the Au Oh NPs@ZIF-67 / PA-6 composite material, i.e., the Au Oh NPs@ZIF-67 / PA-6 substrate.

[0076] Experimental Example 1

[0077] The deposition time in step (5) of Example 1 was changed to 5 min, 10 min, 15 min, 20 min, 30 min, and 60 min, respectively. The SERS of the flexible Au TOHs@ZIF-67 / PA-6 substrate was obtained as follows: Figure 4 shown; from Figure 4 It can be seen that a strong SERS signal can be obtained after deposition for 15 minutes.

[0078] Experimental Example 2

[0079] 1. Weigh the chlorfenapyr solid pesticide and disperse it in water. Dilute the chlorfenapyr solution with water to 1 μg / mL (1 ppm) to prepare a chlorfenapyr simulated solution.

[0080] The substrates of Example 1 and Comparative Examples 1-2 were placed on tin foil, and then 1 ppm of chlorfenapyr simulated liquid was dropped on the substrates, which were then placed on a micro-Raman spectrometer rack and tested using a 785 nm laser. The test results are shown in FIG. Figure 5 .

[0081] from Figure 5 A strong characteristic peak of chlorfenapyr can be observed in the spectrum at 1088 cm -1 The intensity of the Raman signal is proportional to the number of chlorfenapyr molecules adsorbed on the composite substrate. By comparing the three substrates, it can be found that the flexible Au TOHs@ZIF-67 / PA-6 substrate of Example 1 has a strong Raman signal.

[0082] 2. Weigh the chlorfenapyr solid pesticide and disperse it in water. Dilute the chlorfenapyr solution with water to different concentrations (10 ng / mL, 20 ng / mL, 100 ng / mL, 200 ng / mL, 500 ng / mL, 1 μg / mL, 2 μg / mL) to prepare chlorfenapyr of different concentrations as sample 1.

[0083] Weigh the solid pesticide cypermethrin and disperse it in cucumber juice. Use cucumber juice to dilute the cypermethrin solution to different concentrations (10 ng / mL, 20 ng / mL, 100 ng / mL, 200 ng / mL, 500 ng / mL, 1 μg / mL, 2 μg / mL) to prepare cypermethrin of different concentrations as sample 2.

[0084] The substrate of Example 1 was placed on tin foil, and the chlorfenapyr solution sample 1 and sample 2 were respectively taken and dropped on the substrate, which was then placed on the rack of a micro-Raman spectrometer and detected using a 785 nm laser. The detection results of Example 1 for sample 1 are shown in FIG. Figure 6 A, Linear graph see Figure 6 D, the test results of Example 1 for sample 2 are shown in Figure 6 B. Linear graph Figure 6 E.

[0085] The chlorfenapyr sample 1 with different concentrations was sprayed on the surface of cucumber, and then wiped with the flexible substrate of Example 1, and then placed on the rack of the micro-Raman spectrometer, and detected by 785nm laser. The detection results are shown in 6C and the linear graph is shown in Figure 6 F.

[0086] Figure 6 The characteristic peak of chlorfenapyr can be observed in the spectrum of -1 At , the intensity of the Raman signal is proportional to the number of chlorfenapyr molecules adsorbed on the flexible Au TOHs@ZIF-67 / PA-6 substrate. However, with the further increase of chlorfenapyr concentration, the adsorption reaches a dynamic equilibrium, while the coverage of Au TOHs@ZIF-67 on PA-6 remains almost unchanged, resulting in saturation of the signal intensity. It can be seen that the detection limit can be as low as 10 ng / mL, and the detection range is wide.

[0087] Experimental Example 3

[0088] A 1 μg / mL chlorfenapyr solution was mixed with a diquat solution (1 μg / mL) to prepare chlorfenapyr doped with diquat as sample 3.

[0089] The substrate of Example 1 was placed on tin foil, and the chlorfenapyr solution sample 3 was taken and dropped on the substrate. The test results are shown in FIG. Figure 7 ,from Figure 7 The characteristic peak of chlorfenapyr at 1088 cm can be clearly observed. -1 The characteristic peak of diquat is 1577cm -1 The detection limit of chlorfenapyr based on the flexible Au TOHs@ZIF-67 / PA-6 substrate SERS detection platform can be as low as 10 ng / mL, and diquat adulterated in chlorfenapyr can be identified.

Claims

1. A method for preparing a Au TOHs@ZIF-67 / PA-6 flexible composite material for highly selective detection of mixed pesticides, comprising the following steps: 1) Synthesis of gold trioctahedrons (Au TOHs) by seed-mediated method; 2) Au TOHs was centrifuged and added to the ZIF-67 solution under continuous stirring. After stirring, the obtained mixture was centrifuged and redispersed in water to obtain Au TOH@ZIF-67 solution; 3) PA-6 was cleaned with alcohol and water under ultrasonic wave, and then immersed in Au TOHs@ZIF-67 solution for reaction, and dried naturally at room temperature to obtain Au TOHs@ZIF-67 / PA-6 composite material.

2. The preparation method according to claim 1, characterized in that: In step 1), gold trioctahedron (Au TOHs) is prepared by the following method: (1) injecting a freshly prepared ice-cold NaBH4 solution into the mixed solution a, stirring and mixing to obtain a seed solution, and diluting with water to obtain a diluted seed solution; (2) According to the final size of Au TOHs, the diluted seed solution is added to the mixed solution b, and the resulting mixture is allowed to stand at 40-50° C. for 5-10 minutes to obtain gold trioctahedrons (Au TOHs).

3. The preparation method according to claim 2, characterized in that: In step (1), the mixed solution a is composed of a mixture of a 0.1M hexadecyltrimethylammonium bromide solution, a 0.01M HAuCl4 solution, and a 0.01M H2PtCl6 solution, and the volume ratio of the hexadecyltrimethylammonium bromide solution, the HAuCl4 solution, and the H2PtCl6 solution is 975:15:

10.

4. The preparation method according to claim 2, characterized in that: In step (1), the concentration of NaBH4 solution is 0.01M, the volume ratio of NaBH4 solution to mixed solution a is (8-12):(50-150), and the seed solution is diluted by diluting 20 μL of seed solution into 10 mL of pure water to obtain a diluted seed solution.

5. The preparation method according to claim 2, characterized in that: In step (1), the mixed solution b is composed of a mixture of a 25 mM hexadecyltrimethylammonium chloride solution, a 0.01 M HAuCl4 solution, a 0.01 M H2PtCl6 solution and a 0.1 M ascorbic acid solution, and the volume ratio of the hexadecyltrimethylammonium chloride solution, the HAuCl4 solution, the H2PtCl6 solution and the ascorbic acid solution is 100:5:0.05:2.

5.

6. The preparation method according to claim 2, characterized in that: In step (2), the volume ratio of the diluted seed solution to the mixed solution b is 250:10755.

7. The preparation method according to claim 1, characterized in that: In step 2), the gold trioctahedron (Au TOHs) is centrifuged by dispersing the Au TOHs obtained in step 1) into an aqueous solution, and centrifuging twice at 7000 rpm, each time for 7 minutes. In step 2), the ZIF-67 solution is prepared by the following method: Dissolve 0.45 g of cobalt nitrate hexahydrate in 3 mL of ultrapure water to obtain a cobalt nitrate hexahydrate solution. Dissolve 5.5 g of dimethylimidazole in 20 mL of ultrapure water. Stir the dimethylimidazole solution at 1000 rpm on a magnetic stirrer. After 1 min, slowly add the cobalt nitrate hexahydrate solution. The solution turns bright purple and stir for 6 h. In step 2), the volume ratio of Au TOHs to ZIF-67 solution after centrifugation is (8-12):1; In step 2), the stirring time is 4-10 minutes; In step 2), the centrifugation is performed at 8000 rpm for 10 minutes.

8. The preparation method according to claim 1, characterized in that: In step 3), PA-6 is immersed in the Au TOH@ZIF-67 solution for a reaction time of 10-20 minutes.

9. An Au TOHs@ZIF-67 / PA-6 flexible composite material for highly selective detection of mixed pesticides, prepared by the method according to any one of claims 1 to 8.

10. The use of the Au TOHs@ZIF-67 / PA-6 flexible composite material for highly selective detection of mixed pesticides according to claim 9, which is used to detect pesticides in liquids or pesticides on solid surfaces, wherein the pesticide is cypermethrin or a mixture of cypermethrin and other pesticides.

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