A colorimetric sensor for detecting pesticides, its preparation method and application

Abstract

This invention discloses a colorimetric sensor for detecting pesticides, its preparation method, and its application, belonging to the field of hazardous substance detection technology. The colorimetric sensor of this invention consists of a capture probe and a signal probe; wherein the capture probe is selected from a thiol-containing nucleic acid aptamer modified with Au-SSM membrane material, i.e., SH-aptamer-Au-SSM; the signal probe is selected from a thiol-containing cDNA modified with AuPt@IL@Fe3O4 nanomaterial, i.e., SH-cDNA-AuPt@IL@Fe3O4. The colorimetric sensor of this invention can specifically identify acetamiprid, and the detection method is simple to operate, requiring no complex pretreatment of the test sample; the detection cost is low, the detection is rapid, and the requirements for detection instruments are low.

Description

Technical Field

[0001] This invention belongs to the field of hazardous substance detection technology, specifically relating to a colorimetric sensor for detecting pesticides, its preparation method, and its application. Background Technology

[0002] Acetamiprid is a novel pyridine insecticide with stomach poison, contact, and strong penetrating effects. It possesses rapid insecticidal efficacy and a long residual effect, making it a systemic insecticide for soil and foliage use. It is widely used in rice, and especially in vegetables, fruit trees, and tea to control some lepidopteran pests. However, biopesticide residues pose a threat to human health. Currently, the detection methods for acetamiprid pesticide residues mainly rely on traditional instrumental analysis techniques, primarily focusing on chromatography, including gas chromatography, gas / liquid chromatography-mass spectrometry (GC-MS), and high-performance liquid chromatography (HPLC). While these methods offer high sensitivity and stability, conventional GC-MS and other techniques for analyzing pesticide residues are costly, time-consuming, and often involve expensive equipment and high solvent consumption, failing to meet the requirements for rapid on-site detection. Therefore, developing a new detection technology that is easy to operate, fast, highly sensitive, and has low requirements for the detection instruments is crucial. Summary of the Invention

[0003] This invention provides a colorimetric sensor comprising a capture probe and a signal probe; wherein the capture probe is selected from a thiol-containing nucleic acid aptamer modified with Au-SSM membrane material, i.e., SH-aptamer-Au-SSM; the signal probe is selected from thiol-containing cDNA modified with nanomaterials, i.e., SH-cDNA-nanomaterials; in this invention, the nanomaterials may be selected from AuPt@IL@Fe3O4, i.e., the signal probe may be selected from SH-cDNA-AuPt@IL@Fe3O4.

[0004] The above SH-aptamer is selected from the following sequences:

[0005] 5'-SH-AAAAAAAAAAAAACTGACACCATATTATGAAGA-3'.

[0006] The above SH-cDNA was selected from the following sequences:

[0007] 5'-SH-AAAAAAAAAAAATCTTCATAATATGG-3'.

[0008] The above-mentioned SH-aptamer-Au-SSM can be prepared by the following methods:

[0009] First, SH-aptamer was activated using TCEP to obtain the SH-aptamer activation system. Then, Au-SSM membrane material was mixed with the SH-aptamer activation system, water was added, and the mixture was incubated at 37°C. After incubation, unbound single-chain SH-aptamer was washed away, and 1% bovine serum albumin was added to block the unbound sites, forming SH-aptamer-Au-SSM.

[0010] The dosage of the Au-SSM membrane material and the SH-aptamer activation system should be such that the SH-aptamer can fully integrate with the Au-SSM membrane material. This can be achieved by using 10 μL of SH-aptamer activation system for every 1-3 Au-SSM membrane materials with a diameter of approximately 5 mm; other dosage ratios are also acceptable. The dosage of water should be sufficient to provide a adequate liquid environment for incubation. This can be achieved by using 80-100 μL of water for every Au-SSM membrane material with a diameter of approximately 5 mm; other dosages are also acceptable, as long as they are within a reasonable range and will not affect the incubation process.

[0011] The above-mentioned Au-SSM membrane material can be prepared by the following methods:

[0012] Cut the metal mesh into small circular pieces to obtain the SSM membrane; then place the SSM membrane in dilute hydrochloric acid for etching until small bubbles are generated, then remove and clean it; add the SSM membrane to 3-aminopropyltriethoxysilane, let it stand, clean it, and dry it; then add the SSM membrane to HAuCl4, let it stand first, then shake it, then add sodium borohydride ice, shake it, let it stand again, and finally remove the SSM membrane and dry it to obtain the Au-SSM membrane material.

[0013] The diameter of the SSM membrane can be selected from 1 to 10 mm; preferably 5 mm.

[0014] The above-mentioned SH-cDNA-AuPt@IL@Fe3O4 can be prepared by the following methods:

[0015] First, SH-cDNA was activated using TCEP to obtain the SH-cDNA activation system. Then, AuPt@IL@Fe3O4 was resuspended in water to obtain the AuPt@IL@Fe3O4 solution. Next, the SH-cDNA activation system was added to the AuPt@IL@Fe3O4 solution and incubated at 37°C. After incubation, the solution was magnetically separated, the supernatant was discarded, water was added and centrifuged to remove unbound single-stranded SH-cDNA. 1% bovine serum albumin was added to block the unbound sites, and then the precipitate was washed and separated to obtain SH-cDNA-AuPt@IL@Fe3O4.

[0016] The amount of SH-cDNA activation system and AuPt@IL@Fe3O4 solution used should be such that SH-cDNA can fully bind with AuPt@IL@Fe3O4. The volume ratio can be selected from 1:1 to 3:1, or other ratio ranges. As long as it is within a reasonable range, it will not affect the incubation process.

[0017] The above AuPt@IL@Fe3O4 nanomaterials can be prepared by the following methods:

[0018] Fe3O4 was dispersed in hydrochloric acid solution and sonicated to magnetically separate the Fe3O4 particles, which were then washed. The Fe3O4 particles were then dispersed in a mixed solution containing ethanol, water, and concentrated ammonia, and tetraethyl orthosilicate (TEOS) was added. The mixture was stirred at room temperature to obtain SiO2@Fe3O4. SiO2@Fe3O4 was magnetically separated, washed, and then dispersed in an ethanol solution containing concentrated ammonia. An ionic liquid was added, and the mixture was stirred at room temperature. After the reaction was complete, the reaction product was magnetically separated, washed, and obtained IL@SiO2@Fe3O4. IL@SiO2@Fe3O4 was then mixed with sodium hydroxide and reacted to etch the SiO2 layer. The reaction product was magnetically separated, washed, and dried to obtain IL@Fe3O4. IL@Fe3O4 was dispersed in trisodium citrate solution and sonicated. HAuCl4 solution and trisodium citrate solution were added, and the mixture was boiled until the solution turned wine red. Then, potassium chloroplatinate and L-ascorbic acid were added, and the mixture was boiled until the solution turned reddish-brown to obtain AuPt@IL@Fe3O4 solution. The AuPt@IL@Fe3O4 solution was centrifuged, and the supernatant was discarded to obtain AuPt@IL@Fe3O4 nanomaterials.

[0019] The above-mentioned ionic liquid is selected from one of 1-aminoethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium perchlorate, and 1-ethyl-3-methylimidazolium nitrate.

[0020] This invention provides the application of the above-mentioned colorimetric sensor in the detection of acetamiprid. Specifically, the colorimetric sensor can be prepared into a detection reagent or kit to achieve qualitative and quantitative detection of acetamiprid in the sample to be tested.

[0021] This invention provides a method for detecting acetamiprid, comprising the following steps:

[0022] Dissolve the signal probe in water, add the capture probe, and incubate at a constant temperature. After incubation, add the sample solution to be tested, and react at room temperature. After the reaction is complete, perform magnetic separation. Add TMB-H2O2 solution to the magnetically separated material and incubate at room temperature. If the solution changes from colorless to blue, it indicates that acetamiprid is present in the sample solution. Measure the absorbance of the reaction solution and compare it with the standard curve to obtain the concentration of acetamiprid.

[0023] The amounts of the signal probe, the sample solution to be tested, and the capture probe can be selected from the following: taking a sample solution of 200 μL as an example, the amount of signal probe can be selected from 10 to 15 μL, and the amount of capture probe can be selected from 1 to 3 pieces. In practical applications, the amounts of each component can be increased or decreased according to the above proportional relationship. However, it should be stated that the implementation of the above technical solution and the achievement of its technical effect do not completely and strictly depend on the above-mentioned range of amounts of each component. For example, when the amount of signal probe added is 5 μL, 15 μL, or 20 μL, the technical solution of the present invention can still be implemented and the technical effect claimed by the present invention can be achieved.

[0024] The composition of the above TMB-H2O2 solution is as follows:

[0025] 40 μL of 100 μM H2O2, 20 μL of 10 μM TMB, and 80 μL of NaAc-HAc buffer at pH 4.5.

[0026] The standard curve mentioned above can be constructed using the following methods:

[0027] Prepare test solutions of acetamiprid at different concentrations; dissolve the signal probe in water, add the capture probe, incubate at a constant temperature, then add acetamiprid solutions of different concentrations, react at room temperature, and perform magnetic separation after the reaction is complete; add TMB-H2O2 solution to the magnetically separated material, incubate at room temperature, and measure the absorbance of the reaction solution at 652 nm; construct a standard curve of acetamiprid concentration-UV absorbance with acetamiprid concentration as the x-axis and UV absorbance as the y-axis.

[0028] The beneficial effects of this invention are as follows:

[0029] The colorimetric sensor of this invention can specifically identify acetamiprid, and the detection method is simple to operate, requiring no complex pretreatment of the sample; the detection cost is low, the detection is rapid, and the requirements for the detection instrument are low. This invention is the first to use a metal mesh as a detection element to prevent sample color interference, and it is easy to remove. Attached Figure Description

[0030] Figure 1 Scanning electron microscope image of Au-SSM membrane material;

[0031] Figure 2Transmission electron microscopy image of AuPt@IL@Fe3O4 nanomaterials;

[0032] Figure 3 This is a schematic diagram of the colorimetric sensor detection principle.

[0033] Figure 4 The results show the detection results of different concentrations of acetamiprid; from left to right, they are 0 ng / mL, 20 ng / mL, 50 ng / mL, 100 ng / mL, 200 ng / mL, 500 ng / mL, 800 ng / mL, and 1000 ng / mL.

[0034] Figure 5 This is a standard curve of acetamiprid concentration versus ultraviolet absorbance; where the horizontal axis represents acetamiprid concentration (ng / mL) and the vertical axis represents ultraviolet absorbance (ao).

[0035] Figure 6 This is a graph showing the test results for different organic pesticides. Detailed Implementation

[0036] This invention provides an Au-SSM membrane material, prepared by the following method:

[0037] A metal mesh (74 μm pore size, 60 μm aperture, Leiko Metal Products Co., Ltd.) was cut into discs approximately 5 mm in diameter (SSM membrane). These discs were then etched in dilute hydrochloric acid for 12 hours until small bubbles were generated. After etching, the discs were removed, cleaned, and then added to 3 mL of 3-aminopropyltriethoxysilane (APTES), ensuring the discs were submerged. The mixture was allowed to stand for 12 hours, then rinsed with ultrapure water and dried. Next, 1 mL of 1% HAuCl4 was added, and the mixture was allowed to stand for 5 minutes, then shaken for 2 minutes. 2 mL of sodium borohydride was added, shaken for 2 minutes, and allowed to stand for another 5 minutes. The SSM membrane was then removed and dried at 60°C to obtain the Au-SSM membrane material.

[0038] Scanning electron microscope image of Au-SSM film material as follows: Figure 1 As shown, approximately 10 nm fine gold nanoparticles (Au NPs) are attached to the stainless steel wire skeleton of the SSM, indicating that Au was successfully synthesized on the SSM, demonstrating the successful synthesis of the Au-SSM film material.

[0039] This invention provides an AuPt@IL@Fe3O4 nanomaterial, which is prepared by the following method:

[0040] 0.1 g Fe3O4 was dispersed in 50 mL of hydrochloric acid (0.01 M) solution and sonicated for 10 min. The Fe3O4 particles were separated using a magnet and washed with ultrapure water. Then, the Fe3O4 particles were dispersed in a mixed solution containing 80 mL of ethanol, 20 mL of water, and 1 mL of concentrated ammonia. 0.21 mL of tetraethyl orthosilicate (TEOS) was added, and the mixture was stirred at room temperature for 6 h to obtain SiO2@Fe3O4. SiO2@Fe3O4 was separated using a magnet, washed with ethanol and ultrapure water, and then redispersed in 80 mL of ethanol solution (containing 1 mL of concentrated ammonia). The mixture was stirred for 30 min, and then 0.1 g / mL of 1-aminoethyl-3-methylimidazolium bromide (ionic liquid, IL) was slowly added while stirring. The mixture was stirred at room temperature for 24 h, and the particles were collected using a magnet and washed three times with ethanol and ultrapure water to obtain IL@SiO2@Fe3O4. IL@SiO2@Fe3O4 was mixed with 5% NaOH and reacted for 48 hours. The SiO2 layer was etched, and the mixture was separated and collected using a magnet. The mixture was washed three times with ultrapure water and then vacuum dried at room temperature to obtain IL@Fe3O4, which was then stored for later use.

[0041] 0.1 g IL@Fe3O4 was dispersed in 3 mL of trisodium citrate solution (1%) and sonicated for 10 min. Then, 5 mL of HAuCl4 solution (0.1%) and 5 mL of trisodium citrate solution (4%) were added, and the solution was boiled at 100 °C for 10 min until it turned wine red. Then, 5 mL of potassium chloroplatinate (1.5 mM) and 5 mL of L-ascorbic acid (5 mM) were added, and the solution was boiled until it turned reddish-brown to obtain AuPt@IL@Fe3O4 nanomaterial solution. The nanomaterial solution was centrifuged at 8000 rpm for 5 min, and the supernatant was discarded to obtain AuPt@IL@Fe3O4 nanomaterial.

[0042] Transmission electron microscopy image of AuPt@IL@Fe3O4 nanomaterials, as shown Figure 2 As shown: AuPt nanoparticles are uniformly loaded on the surface of IL@Fe3O4, with an average particle size of about 5 nm.

[0043] Other materials used in this invention, unless otherwise stated, are commercially available. Other terms used in this invention, unless otherwise specified, generally have the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. The following embodiments are merely illustrative and not intended to limit the scope of the invention in any way.

[0044] Example 1

[0045] Fabrication of a colorimetric sensor:

[0046] This embodiment provides a colorimetric sensor composed of a capture probe and a signal probe; wherein, the capture probe is selected from a nucleic acid aptamer with thiol groups modified by Au-SSM membrane material, namely SH-aptamer-Au-SSM; the signal probe is selected from cDNA with thiol groups modified by nanomaterials, namely SH-cDNA-nanomaterials; the nanomaterials are selected from AuPt@IL@Fe3O4 nanomaterials, that is, the signal probe is selected from SH-cDNA-AuPt@IL@Fe3O4.

[0047] The aforementioned SH-aptamer is a nucleic acid aptamer with a thiol group modified at its 5' end. The sequence of the nucleic acid aptamer is as follows:

[0048] 5'-AAAAAAAAAAAAACTGACACCATATTATGAAGA-3' (SEQ ID NO: 1).

[0049] The above-mentioned SH-cDNA is cDNA with a thiol group modified at the 5' end. The cDNA sequence is as follows:

[0050] 5'-AAAAAAAAAAAATCTTCATAATATGG-3' (SEQ ID NO: 2).

[0051] The above-mentioned capture probe SH-aptamer-Au-SSM is assembled by the following method:

[0052] First, tris(2-carboxyethyl)phosphine (TCEP) was used to activate the thiol-containing nucleic acid aptamer. The activation process was as follows: 6 μL of TCEP (1 mM) was added to 10 μL of SH-aptamer (10 μM), and the mixture was incubated in a metal bath at 37°C for 30 min to obtain the SH-aptamer activation system. Then, a piece of Au-SSM membrane material was placed in the above SH-aptamer activation system (16 μL), followed by the addition of 80 μL of ultrapure water. The mixture was incubated in a metal bath at 37°C for 12 h. The SH-aptamer-Au-SSM disc was then removed and washed with ultrapure water to remove unbound single-stranded SH-aptamer. 1% bovine serum albumin (BSA) was added to block the unbound sites, forming the capture probe SH-aptamer-Au-SSM.

[0053] The above signal probe SH-cDNA-AuPt@IL@Fe3O4 was assembled using the following method:

[0054] First, SH-cDNA was activated using TCEP. The activation process involved adding 12 μL of TCEP (1 mM) to 20 μL of SH-cDNA (10 μM) and incubating in a metal bath at 37°C for 30 min to obtain the SH-cDNA activation system. Then, 1 mL of the above AuPt@IL@Fe3O4 nanomaterial solution was centrifuged, the precipitate was retained, the supernatant was removed, and 30 μL of ultrapure water was added to the precipitate to resuspend it. Next, the above SH-cDNA activation system (10 μM) was added to 30 μL of AuPt@IL@Fe3O4 nanomaterial solution and incubated at 37°C for 12 h. Finally, the solution was magnetically separated, the supernatant was discarded, ultrapure water was added and centrifuged again to remove unbound single-stranded SH-cDNA, 1% bovine serum albumin (BSA) was added to block the unbound sites, and then the mixture was washed and separated (the material was separated with a magnet, the BSA solution was discarded, 1 mL of ultrapure water was added, and centrifuged for 30 s) to obtain the signal probe SH-cDNA-AuPt@IL@Fe3O4.

[0055] The detection principle of this invention is as follows:

[0056] When acetamiprid is present, aptamer preferentially binds to it, thereby competing with the SH-cDNA-AuPt@IL@Fe3O4 signal probe. The signal probe can be separated using a magnet; in a TMB-H2O2 solution, TMB can be oxidized to blue ox-TMB. The detection principle is as follows: Figure 3 As shown.

[0057] Example 2

[0058] Plot the standard curve:

[0059] Prepare acetamiprid test solutions at concentrations of 0 ng / mL, 20 ng / mL, 50 ng / mL, 100 ng / mL, 200 ng / mL, 500 ng / mL, 800 ng / mL, and 1000 ng / mL. Dissolve 10 μL of the signal probe in 90 μL of ultrapure water, add one capture probe, and incubate at 37°C for 2 h. Then add 50 μL of the above-mentioned concentrations of acetamiprid. Incubate the mixture at room temperature for 50 min for magnetic separation. Add a TMB-H2O2 solution [40 μL H2O2 (100 mM), 20 μL TMB (10 mM), 80 μL NaAc-HAc buffer (pH = 4.5)] to the magnetically separated solution, mix and incubate at room temperature for 5 min. The solution will change from colorless to blue. Then scan the reacted solution at a wavelength of 652 nm using a UV-Vis spectrophotometer to measure the UV absorption intensity.

[0060] Detection results of different concentrations of acetamiprid, such as Figure 4As shown, the color of the liquid in each tube changed from light blue to dark blue as the concentration of acetamiprid increased. The absorbance test results are shown in Table 1.

[0061] Table 1

[0062] Acetamiprid concentration (ng / mL) Absorbance value (ao) deviation 0 0.20084 0.00549 20 0.21102 0.00869 50 0.21665 0.00897 100 0.22518 0.00937 200 0.24589 0.00575 500 0.29576 0.00631 800 0.35213 0.00481 1000 0.38596 0.00909

[0063] A standard curve of acetamiprid concentration versus ultraviolet absorbance was constructed with acetamiprid concentration on the x-axis and ultraviolet absorbance on the y-axis, as shown below. Figure 5 As shown. The nucleic acid aptamer sensor of the present invention exhibits a linear range up to 1000 ng / mL, with a detection limit as low as 0.05 ng / mL. The fitting equation is y = 0.00018x + 0.20538, R0 2 =0.99785.

[0064] Example 3

[0065] Colorimetric sensor accuracy verification:

[0066] Prepare a 50 ng / mL acetamiprid solution as the test sample solution.

[0067] 10 μL of the signal probe was dissolved in 90 μL of ultrapure water, and one capture probe was added. The mixture was incubated at 37°C for 2 h, followed by the addition of 50 μL of the sample solution. The mixture was allowed to react at room temperature for 50 min, resulting in magnetic separation. A TMB-H2O2 solution [40 μL H2O2 (100 μM), 20 μL TMB (10 μM), 80 μL NaAc-HAc buffer (pH = 4.5)] was added to the magnetically separated solution, and the mixture was incubated at room temperature for 5 min. The solution changed from colorless to blue, indicating the presence of acetamiprid in the sample solution. The reacted solution was then scanned at 652 nm using a UV-Vis spectrophotometer, and the UV absorption intensity was measured to be 0.21365ao. The acetamiprid concentration was found to be 45.9 ng / mL according to the standard curve. This concentration is close to the concentration of the sample solution, within 5 ng / mL, indicating that the colorimetric sensor of this invention has high accuracy.

[0068] Example 4

[0069] Specificity verification:

[0070] Specificity verification of colorimetric sensor:

[0071] The following sample solutions were prepared: acetamiprid solution, carbendazim solution, chlorpyrifos solution, phoxim solution, and parathion solution, all at a concentration of 500 ng / mL. The colorimetric sensor was incubated using the method described in Example 3 to verify the specificity of the colorimetric sensor of this invention.

[0072] The experimental results are shown in Table 2:

[0073] Table 2

[0074] Organic pesticides Absorbance value (ao) Acetamiprid 0.30242 Carbendazim 0.08815 Chlorpyrifos 0.07134 Phosphine 0.08052 dithion 0.06564

[0075] As shown in Table 2, the absorbance value of acetamiprid is significantly higher than that of other organic pesticides. Figure 6 Based on the data in Table 2, this sensor more intuitively displays the absorbance of acetamiprid. Therefore, the colorimetric sensor of this invention has high specificity for acetamiprid.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A colorimetric sensor characterized in that, The signal probe is selected from a thiol group cDNA (SH-cDNA) modified by AuPt@IL@Fe3O4 nanomaterial, namely SH-cDNA-AuPt@IL@Fe3O4. The nucleic acid sequence of the aptamer is shown as SEQ ID NO:1, and the sequence is as follows: 5'-AAAAAAAAAAAACTGACACCATATTATGAAGA-3'. The nucleic acid sequence of the cDNA is shown as SEQ ID NO:2, and the sequence is as follows: 5'-AAAAAAAAAAAATCTTCATAATATGG-3'.

2. The colorimetric sensor of claim 1, wherein, The capture probe is prepared by the following method: First, activate SH-aptamer by TCEP to obtain SH-aptamer activation system; then, mix Au-SSM film material with SH-aptamer activation system, add water, and incubate at 37 DEG C; after incubation, remove unbound single-stranded SH-aptamer by washing, add 1% bovine serum albumin to block unbound sites, and form SH-aptamer-Au-SSM, namely the capture probe.

3. The colorimetric sensor of claim 2, wherein, The Au-SSM film material is prepared by the following method: Cut the metal mesh into small round pieces to obtain SSM film; then, place the SSM film in dilute hydrochloric acid for corrosion, take out after small bubbles are generated, and clean; add the SSM film to 3-aminopropyl triethoxysilane, stand, clean, and dry; then, add the SSM film to HAuCl4, stand first, then shake, then add ice sodium borohydride and shake, then stand again, finally take out the SSM film, dry, and obtain Au-SSM film material.

4. The colorimetric sensor of claim 1, wherein, The signal probe is prepared by the following method: First, activate SH-cDNA by TCEP to obtain SH-cDNA activation system; then, resuspend AuPt@IL@Fe3O4 in water to obtain AuPt@IL@Fe3O4 solution; then, add the SH-cDNA activation system to the AuPt@IL@Fe3O4 solution, and incubate at 37 DEG C; after incubation, magnetically separate the solution, discard the supernatant, add water and centrifuge to remove unbound single-stranded SH-cDNA, add 1% bovine serum albumin to block unbound sites, then wash and separate the precipitate, and obtain SH-cDNA-AuPt@IL@Fe3O4, namely the signal probe.

5. The colorimetric sensor of claim 4, wherein, The AuPt@IL@Fe3O4 nanomaterial is prepared by the following method: Fe3O4 is dispersed in hydrochloric acid solution, and ultrasonic treatment is performed, and Fe3O4 particles are separated by magnetic separation and washed; then the Fe3O4 particles are dispersed in a mixed solution containing ethanol, water and concentrated ammonia water, tetraethyl orthosilicate (TEOS) is added, and stirring is performed at room temperature to obtain SiO2@Fe3O4; the SiO2@Fe3O4 is separated by magnetic separation and washed, and then dispersed in an ethanol solution containing concentrated ammonia water, stirred, and an ionic liquid is added, and the reaction is stirred at room temperature; after the reaction is completed, the reaction product is collected by magnetic separation and washed to obtain IL@SiO2@Fe3O4; the IL@SiO2@Fe3O4 is mixed with sodium hydroxide to etch the SiO2 layer, and the reaction product is collected by magnetic separation, washed and dried to obtain IL@Fe3O4; the IL@Fe3O4 is dispersed in a trisodium citrate solution, ultrasonic treatment is performed, and a HAuCl4 solution and a trisodium citrate solution are added, and boiled until the solution is wine red; then potassium chloroplatinate and L-ascorbic acid are added, and boiled until the solution is red-brown to obtain an AuPt@IL@Fe3O4 solution; the AuPt@IL@Fe3O4 solution is centrifuged, and the supernatant is discarded to obtain an AuPt@IL@Fe3O4 nanomaterial.

6. The colorimetric sensor of claim 5, wherein, The ionic liquid is selected from one of 1-amine ethyl-3-methyl imidazole bromide, 1-ethyl-3-methyl imidazole chloride, 1-ethyl-3-methyl imidazole hexafluorophosphate, 1-ethyl-3-methyl imidazole perchlorate, and 1-ethyl-3-methyl imidazole nitrate.

7. The use of the colorimetric sensor according to any one of claims 1-6 in the detection of acetamiprid.

8. A method for detecting acetamiprid, characterized by, The colorimetric sensor according to claim 1 is used, and the steps are as follows: The signal probe is dissolved in water, the capture probe is added, and constant temperature incubation is performed; after the incubation is completed, the sample solution to be detected is added, and reaction is performed at room temperature; after the reaction is completed, magnetic separation is performed; the TMB-H2O2 solution is added to the magnetic separation product, and incubation is performed at room temperature; if the solution changes from colorless to blue, it indicates that acetamiprid exists in the sample solution to be detected; The absorbance of the reaction solution is measured, and the concentration of acetamiprid can be obtained by comparing the standard curve.

9. The detection method according to claim 8, characterized in that, The composition of the TMB-H2O2 solution is as follows: 40 μL of H2O2 with a concentration of 100 μM, 20 μL of TMB with a concentration of 10 μM, and 80 μL of NaAc-HAc buffer with a pH value of 4.

5.

10. The method of claim 8, wherein, The standard curve is constructed by the following method: Different concentrations of acetamiprid sample solutions are prepared; the signal probe is dissolved in water, the capture probe is added, and constant temperature incubation is performed; then different concentrations of acetamiprid solutions are added, and reaction is performed at room temperature; after the reaction is completed, magnetic separation is performed; the TMB-H2O2 solution is added to the magnetic separation product, and incubation is performed at room temperature; the absorbance value of the reaction solution at 652 nm is measured; the concentration of acetamiprid is taken as the abscissa, and the ultraviolet absorbance is taken as the ordinate to construct the standard curve of the concentration of acetamiprid-ultraviolet absorbance.

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