SERS (Surface Enhanced Raman Scattering) sensing method for pesticide residues and micro-nano plastics based on three-dimensional Ag / Al (OH) 3 / Al sensor

Abstract

The invention provides an SERS (Surface Enhanced Raman Scattering) sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al (OH) 3 / Al sensor, and belongs to the technical field of analytical chemistry. The method comprises the following steps: preparing aluminum hydroxide nanosheets based on a hydrothermal method, and performing amination treatment on the aluminum hydroxide nanosheets; a gold nanoparticle AuNPs seed layer is formed on the aluminum hydroxide nanosheet subjected to amination treatment, and an AuNPs functionalized aluminum hydroxide nanosheet is obtained; then, immersing the silver-doped Ag / Al (OH) 3 / Al array structure in a mixed solution containing silver ions, reducing the silver ions through a reducing agent, and depositing silver nanoparticles AgNPs on the surface of the silver-doped Ag / Al (OH) 3 / Al array structure; the three-dimensional Ag / Al (OH) 3 / Al array structure is used as a substrate of the SERS sensor, and pesticide residues and micro-nano plastic are detected. The periodic array substrate with a uniform structure is prepared, excellent SERS (Surface Enhanced Raman Scattering) performance is realized, and the limitation of a traditional Raman technology in the aspect of uniformity is effectively overcome, so that the detection effect of pesticide residues and micro-nano plastics is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, and in particular to a method based on three-dimensional Ag / Al(OH) 3 / Al sensor for pesticide residues and SERS sensing method of micro-nano plastics. Background Art

[0002] With the rapid development of industrialization and agriculture, pesticide residues and micro-nano plastics have become global environmental and health issues. The accumulation of pesticide residues in food poses a threat to human health, while micro-nano plastics, as emerging pollutants, not only directly affect human health, but are also associated with a variety of environmental toxic chemicals. Therefore, the development of a highly sensitive and selective detection technology is crucial for monitoring and controlling these pollutants.

[0003] As a powerful analytical tool, surface enhanced Raman scattering (SERS) technology is widely used in chemistry, medicine, biology and other fields because it can provide information at the molecular level. The signal enhancement of SERS mainly comes from the electromagnetic field enhancement of the plasma on the substrate, which enhances the Raman signal by several orders of magnitude, thereby realizing single-molecule detection. In particular, SERS technology has advantages in analyzing aqueous samples because water is a very weak Raman scatterer. However, traditional Raman spectroscopy is limited in application due to its extremely weak signal intensity, and the weak Raman signal is often masked by the fluorescent background signal. Therefore, the research on SERS technology mainly focuses on using the localized surface plasmon resonance (LSPR) phenomenon to enhance the Raman signal intensity.

[0004] Although SERS technology has shown great potential, it still faces challenges in practical applications. The uneven distribution of metal nanoparticles on the SERS substrate will lead to spatially uneven amplification, which in turn affects the reproducibility of the SERS signal. In addition, the stronger the enhancement, the smaller the hot spot, and the lower the probability of finding the hot spot, which makes SERS difficult to be widely used in practical detection. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a three-dimensional Ag / Al(OH) 3 The SERS sensing method of pesticide residues and micro-nano plastics based on Al / Al sensors was used to prepare a periodic array substrate with a uniform structure, achieving excellent SERS performance and effectively overcoming the limitations of traditional Raman technology in terms of uniformity, thereby significantly improving the detection effect of pesticide residues and micro-nano plastics.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A three-dimensional Ag / Al(OH) 3The SERS sensing method of pesticide residues and micro-nano plastics using a / Al sensor comprises the following steps:

[0008] Based on the hydrothermal method, aluminum hydroxide nanosheets are prepared, and the aluminum hydroxide nanosheets are subjected to an amination treatment;

[0009] Forming a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheet after the amination treatment to obtain an AuNPs-functionalized aluminum hydroxide nanosheet;

[0010] The AuNPs-functionalized aluminum hydroxide nanosheet is immersed in a mixed solution containing silver ions, the silver ions are reduced by a reducing agent, and silver nanoparticles AgNPs are deposited on the surface of the AuNPs-functionalized aluminum hydroxide nanosheet to obtain a three-dimensional Ag / Al(OH) 3 / Al array structure;

[0011] The three-dimensional Ag / Al(OH) 3 / Al array structure is used as the substrate of SERS sensor to detect pesticide residues and micro-nano plastics.

[0012] Preferably, based on the hydrothermal method, the process for preparing aluminum hydroxide nanosheets is as follows: select aluminum foil, clean and cut the aluminum foil, then mix the treated aluminum foil with an alkaline solution to form a slurry, load the slurry into a stainless steel reactor, and place it in a hydrothermal reaction equipment for heating reaction treatment; after the reaction is completed, naturally cool the stainless steel reactor to room temperature, take out the reaction product, filter and wash it with deionized water, and dry it to obtain aluminum hydroxide nanosheets.

[0013] Preferably, the process of amination treatment of the aluminum hydroxide nanosheets is: at room temperature, immersing the aluminum hydroxide nanosheets in an ethylenediamine ethanol solution, the concentration of the ethylenediamine ethanol is 25 vol%, the immersion time is 2h, the surface of the aluminum hydroxide nanosheets is amination treated, and the surface is cleaned with ethanol after the treatment.

[0014] Preferably, a gold nanoparticle AuNPs seed layer is formed on the aluminum hydroxide nanosheet after the amination treatment to obtain the AuNPs functionalized aluminum hydroxide nanosheet. The process is as follows: the aluminum hydroxide nanosheet after the amination treatment is immersed in a 0.1wt% chloroauric acid solution for 2 hours, and the aluminum hydroxide nanosheet after the amination treatment interacts with the gold precursor through the amino group to adsorb the gold precursor on the surface of the aluminum hydroxide nanosheet; then the aluminum hydroxide nanosheet loaded with the gold precursor is immersed in a sodium borohydride aqueous solution for 2 minutes to reduce the gold precursor to gold atoms and form a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheet; finally, the aluminum hydroxide nanosheet is rinsed with deionized water and ethanol to remove the unreacted reducing agent and the unadsorbed gold precursor, and dried to obtain the AuNPs functionalized aluminum hydroxide nanosheet.

[0015] Preferably, the mixed solution containing silver ions is prepared from deionized water, silver nitrate solution and ethylenediaminetetraacetic acid solution, the concentration of the silver nitrate solution is 100 mM, and the concentration of the ethylenediaminetetraacetic acid solution is 50 mM.

[0016] Preferably, the preparation process of the mixed solution containing silver ions is as follows: add 5 ml of silver nitrate solution and 5 ml of ethylenediaminetetraacetic acid solution into 10 ml of deionized water, and stir magnetically for 15 minutes to obtain the mixed solution containing silver ions.

[0017] Preferably, silver ions are reduced by a reducing agent to deposit silver nanoparticles AgNPs on the surface of the AuNPs-functionalized aluminum hydroxide nanosheets to obtain a three-dimensional Ag / Al(OH) 3 The process of forming the three-dimensional Ag / Al(OH)2O3 array structure is as follows: immersing the AuNPs-functionalized aluminum hydroxide nanosheets in the mixed solution containing silver ions, then adding 5 ml of a reducing agent and stirring until the silver nanoparticles AgNPs are uniformly deposited, and finally rinsing with deionized water and drying to obtain the three-dimensional Ag / Al(OH)2O3 array structure. 3 / Al array structure.

[0018] Preferably, the reducing agent is L-ascorbic acid at a concentration of 25 mM.

[0019] Preferably, the three-dimensional Ag / Al(OH) 3 / Al array structure as the substrate of SERS sensor to detect pesticide residues and micro-nano plastics, including: using the three-dimensional Ag / Al(OH) 3 / Al array structure as the substrate, the detection limit of CV molecules is 10 -8 M, relative standard deviation value is less than 10%, and the detection concentration is less than 25 μg / ml for PS microspheres of different sizes.

[0020] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0021] The present invention prepares a three-dimensional Ag / Al(OH) 3 The / Al array structure is used as the SERS substrate, and the surface plasmon resonance effect is used to significantly enhance the Raman signal, achieving high-sensitivity and high-uniformity detection of pesticide residues and micro-nano plastics, overcoming the shortcomings of traditional Raman technology such as weak signal and poor uniformity, and providing an effective analytical means for food safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 The present invention is a three-dimensional Ag / Al(OH) 3 Flow chart of the SERS sensing method for pesticide residues and micro-nano plastics using / Al sensors;

[0024] Figure 2 Schematic diagram of the synthesis process provided in Example 1 of the present invention; wherein (a) represents an image of aluminum foil, and (b) represents Al(OH) 3 Nanosheet images, (c) shows three-dimensional Ag / Al(OH) 3 / Al image, (d) represents the SERS detection image;

[0025] Figure 3 The three-dimensional Ag / Al(OH) provided in Example 1 of the present invention 3 / Al structure characterization data diagram; where (a) represents Al and Ag / Al(OH) 3 / Al XRD spectrum, (b) represents Al, Al(OH) 3 / Al nanosheets and Ag / Al(OH) 3 Raman spectrum of Ag / Al(OH) 3 / EDS spectrum of Al;

[0026] Figure 4 The three-dimensional Ag / Al(OH) prepared at different Ag deposition times provided in Example 1 of the present invention 3 / Al structure SEM image; wherein, (a) represents the SEM image of the deposition time of 2 min, (b) represents the SEM image of the deposition time of 5 min, (c) represents the SEM image of the deposition time of 7 min, and (d) represents the SEM image of the deposition time of 10 min;

[0027] Figure 5 The different concentrations of AgNO provided in Example 1 of the present invention 3 Prepared three-dimensional Ag / Al(OH) 3 / Al structure SEM image; wherein, (a) represents the SEM image at a concentration of 25 mM, (b) represents the SEM image at a concentration of 50 mM, (c) represents the SEM image at a concentration of 100 mM, and (d) represents the SEM image at a concentration of 200 mM;

[0028] Figure 6 The three-dimensional Ag / Al(OH) prepared in Example 1 of the present invention 3 SERS spectra of CV adsorbed on / Al structure; (a) shows SERS spectra at different reaction times, (b) shows SERS spectra at different AgNO 3 The SERS spectra under different concentrations, (c) represents the SERS spectra under different treatment processes;

[0029] Figure 7 The three-dimensional Ag / Al(OH) 3 / Al structure is a performance test data diagram of the SERS substrate; where (a) represents adsorption on Al(OH) 3 The SERS spectra of CV at different concentrations on Ag substrates are shown in Figure 2. (b) shows the SERS spectra of CV at 20 different points on the substrate; (c) shows the SERS spectra of CV at 915 cm -1 The corresponding RSD value at 1172 cm -1 The corresponding RSD value at 1586 cm -1 The corresponding RSD value at 1620 cm -1 The corresponding RSD value at

[0030] Figure 8 The SERS spectra of pesticide standard samples of different concentrations provided in Example 1 of the present invention; wherein (a) represents the SERS spectrum corresponding to the pesticide triazophos, (b) represents the SERS spectrum corresponding to the pesticide diquat, and (c) represents the SERS spectrum corresponding to the pesticide fomphos;

[0031] Fig. 9The Raman spectrum of the multi-component pesticide provided in Example 1 of the present invention; wherein the pesticides in (a), (b) and (c) are two components, and the pesticide in (d) is three components, including 10 -6 M of fofophos, 10 -6 M's Diquat and 10 -7 M's triazophos;

[0032] Fig.10 The SERS spectra of PS solutions of different sizes at the same concentration provided in Example 2 of the present invention; wherein (a) represents the SERS spectrum of a PS solution with a concentration of 2.5 mg / ml, (b) represents the SERS spectrum of a PS solution with a concentration of 250 μg / ml, and (c) represents the SERS spectrum of a PS solution with a concentration of 25 mg / ml. DETAILED DESCRIPTION

[0033] 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.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Embodiment 1

[0036] Reference Figure 1 The present invention provides a three-dimensional Ag / Al(OH) 3 The SERS sensing method of pesticide residues and micro-nano plastics using a / Al sensor comprises the following steps:

[0037] Step 100: preparing aluminum hydroxide nanosheets based on a hydrothermal method, and performing an amination treatment on the aluminum hydroxide nanosheets;

[0038] Step 200: forming a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheet after the amination treatment to obtain an AuNPs-functionalized aluminum hydroxide nanosheet;

[0039] Step 300: immersing the AuNPs-functionalized aluminum hydroxide nanosheet in a mixed solution containing silver ions, reducing the silver ions with a reducing agent, and depositing silver nanoparticles AgNPs on the surface of the AuNPs-functionalized aluminum hydroxide nanosheet to obtain a three-dimensional Ag / Al(OH) 3 / Al array structure;

[0040] Step 400: The three-dimensional Ag / Al(OH) 3 / Al array structure is used as the substrate of SERS sensor to detect pesticide residues and micro-nano plastics.

[0041] In step 100, the process of preparing aluminum hydroxide nanosheets based on the hydrothermal method is as follows: aluminum foil is selected, and the aluminum foil is cleaned and cut, and then the treated aluminum foil is mixed with an alkaline solution to form a slurry, and the slurry is loaded into a stainless steel reactor, and placed in a hydrothermal reaction device for heating reaction treatment; after the reaction is completed, the stainless steel reactor is naturally cooled to room temperature, the reaction product is taken out, filtered and washed with deionized water, and dried to obtain aluminum hydroxide nanosheets. The process of amination treatment of aluminum hydroxide nanosheets is as follows: at room temperature, the aluminum hydroxide nanosheets are immersed in an ethylenediamine ethanol solution, the concentration of ethylenediamine ethanol is 25vol%, and the immersion time is 2h, and the surface of the aluminum hydroxide nanosheets is aminated, and the surface is washed with ethanol after the treatment.

[0042] In step 200, a gold nanoparticle AuNPs seed layer is formed on the aluminum hydroxide nanosheets after the amination treatment to obtain the AuNPs-functionalized aluminum hydroxide nanosheets. The process is as follows: the aluminum hydroxide nanosheets after the amination treatment are immersed in a 0.1wt% chloroauric acid solution for 2 hours, and the aluminum hydroxide nanosheets after the amination treatment interact with the gold precursor through the amino group to adsorb the gold precursor on the surface of the aluminum hydroxide nanosheets; then, the aluminum hydroxide nanosheets loaded with the gold precursor are immersed in a sodium borohydride aqueous solution for 2 minutes to reduce the gold precursor to gold atoms and form a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheets; finally, the aluminum hydroxide nanosheets are rinsed with deionized water and ethanol to remove the unreacted reducing agent and the unadsorbed gold precursor, and dried to obtain the AuNPs-functionalized aluminum hydroxide nanosheets.

[0043] In step 300, a mixed solution containing silver ions is prepared from deionized water, a silver nitrate solution and an ethylenediaminetetraacetic acid solution, wherein the concentration of the silver nitrate solution is 100 mM, and the concentration of the ethylenediaminetetraacetic acid solution is 50 mM. The preparation process of the mixed solution containing silver ions is as follows: 5 ml of the silver nitrate solution and 5 ml of the ethylenediaminetetraacetic acid solution are added to 10 ml of deionized water, and magnetic stirring is performed for 15 minutes to obtain a mixed solution containing silver ions.

[0044] In step 400, silver ions are reduced by a reducing agent to deposit silver nanoparticles AgNPs on the surface of the AuNPs-functionalized aluminum hydroxide nanosheets to obtain a three-dimensional Ag / Al(OH) 3The process of forming the three-dimensional Ag / Al(OH)2O3 array structure is as follows: the AuNPs-functionalized aluminum hydroxide nanosheets are immersed in a mixed solution containing silver ions, then 5 ml of a reducing agent is added and stirred until the silver nanoparticles AgNPs are uniformly deposited, and finally rinsed with deionized water and dried to obtain a three-dimensional Ag / Al(OH)2O3 array structure. 3 / Al array structure. The reducing agent is L-ascorbic acid with a concentration of 25 mM.

[0045] According to the above, the three-dimensional Ag / Al(OH) 3 Preparation and characterization of the / Al array structure as a SERS substrate Figure 2 As shown. Figure 2 Comparing the images in (a), (b), and (c), we can see that the silver nanoparticles are uniformly and densely modified on the aluminum hydroxide nanosheets by the seed-mediated method. The images obtained by SERS detection are as follows: Figure 2 As shown in (d) in the figure, the feasibility of this method is proved. Figure 3 (b) shows that after epitaxial growth of aluminum hydroxide, Al(OH) 3 The characteristic peaks of the nanosheets are clearly shown, while the Raman peaks of the aluminum hydroxide nanosheets disappear after the surface is modified with silver nanoparticles. Figure 3 (a) shows the XRD pattern of the substrate, and the diffraction peak at 38.1° is attributed to the (111) crystal plane of face-centered cubic (fcc) silver, indicating that silver nanoparticles were successfully decorated on the surface of aluminum hydroxide nanosheets by the seed-mediated method. 3 The EDS elemental spectrum shows that AgNPs have been successfully decorated on Al(OH) 3 On the base, such as Figure 3 (c) as shown.

[0046] In order to further characterize the three-dimensional Ag / Al(OH) 3 / Al array structure formation, this example conducted a time-dependent experiment at a silver nitrate concentration of 50mM to determine the optimal time for the array structure, and the results obtained are as follows Figure 4 As shown in the figure, specifically: within the first 2 minutes of the reaction, the color of the reaction solution changed from colorless to dark brown, and the aluminum hydroxide nanosheets changed from white to gray-brown, which indicates that AgNPs were formed on the surface of the aluminum hydroxide nanosheets. Within 2 minutes, a small amount of AgNPs was deposited on the surface of the aluminum hydroxide nanosheets, such as Figure 4 As shown in (a) in Figure 5, after 5 minutes, a large number of AgNPs were decorated on the aluminum hydroxide nanosheets, as shown in Figure 5. Figure 4 As shown in (b), Ag / Al(OH) with densely distributed AgNPs was obtained within 7 minutes. 3 Nanosheet arrays, such as Figure 4As shown in (c) in the figure, as the reaction time is further extended to 10 min, additional AgNPs are deposited on the surface of the aluminum hydroxide nanosheets, resulting in the appearance of excessive silver nanoparticles on the aluminum hydroxide nanosheets, as shown in Figure 4 As shown in (d) in the figure. Therefore, as the deposition time increases, the size of the Ag nanoparticles continues to grow, while the interparticle gaps between adjacent nanoparticles also decrease accordingly. The above results further indicate that the size of the Ag nanoparticles and the interparticle gaps can be controlled by adjusting the growth deposition time, and that periodic uniform three-dimensional Ag / Al(OH) can be rapidly synthesized within 7 minutes at room temperature. 3 / Al array structure.

[0047] See also Figure 5 , at 25 mM low AgNO 3 At concentrations, many smaller-sized silver nanoparticles are evenly distributed on the aluminum hydroxide nanosheets, such as Figure 5 As shown in (a). 3 With the increase of concentration, the diameter of silver nanoparticles becomes larger, e.g. Figure 5 When the concentration of silver nitrate exceeds 100 mM, excess Ag nanoparticles will be deposited on the surface of Ag-aluminum hydroxide nanosheets, as shown in (b) and (c). Figure 5 As shown in (d) in .

[0048] Finally, in order to further characterize the 3D Ag / Al(OH) 3 / Al array structure as SERS substrate, amination process in three-dimensional Ag / Al(OH) 3 When the aluminum hydroxide nanosheets are not aminated or chloroauric acid is used instead of silver nitrate, under the same other conditions, Figure 6 In (a), it can be observed that the number and size of silver nanoparticles are closely related to the amination process. Figure 6 (b) shows the 3 Three-dimensional Ag / Al(OH) prepared at concentration 3 SERS spectrum of crystal violet (CV) adsorbed on the substrate of AgNO / Al array structure. It can be observed from the figure that the SERS intensity increases with the increase of AgNO 3 At 100 mM AgNO 3 At a concentration of 1.5 wt. % AgNO, uniform and dense silver nanoparticles are deposited on the surface of aluminum hydroxide nanosheets, which helps to generate uniform SERS signals. 3 When the concentration exceeded 100 mM, some excess Ag nanoparticles were deposited on the surface of the initial Ag-aluminum hydroxide nanosheets.

[0049] Secondly, refer to Figure 6In (c), the SERS signal intensity of the substrate without amination and gold seed treatment is the lowest. This is because fewer silver nanoparticles usually produce weaker SERS responses compared to other complex nanostructures. Only when a proper amount of silver nanoparticles are deposited on the substrate, it exhibits good SERS performance.

[0050] Finally, based on the above content, the three-dimensional Ag / Al(OH) with excellent SERS performance was prepared by adjusting the experimental parameters. 3 The optimal conditions for the Ag / Al array structure were determined to effectively control the size of the Ag nanoparticles and the gaps between adjacent Ag nanoparticles. The most sensitive substrate was found by performing experiments. In this example, a three-dimensional Ag / Al(OH) prepared by amination was selected. 3 / Al array structure, AgNO 3 The concentration is 100mM.

[0051] In determining the three-dimensional Ag / Al(OH) 3 After the optimal technical solution of the / Al array structure, CV was used as a model probe molecule to evaluate the three-dimensional Ag / Al(OH) 3 SERS performance of / Al array structure as substrate. Figure 7 (a) in 10 -8 M concentration, the characteristic peaks of CV can still be clearly identified, indicating that the prepared SERS substrate has high sensitivity and potential for detecting other target molecules. The enhancement factor (EF) of the substrate is calculated to be 1.92×10 5 At the same time, when Ag / Al(OH) 3 / Al substrate immersion 10 -5 When the CV solution of M was added, the SERS spectra were recorded using a portable Raman spectrometer, such as Figure 7 As shown in (b), (c), (e), (f), and (g) in the figure, the 915 cm -1 、1172cm -1 、1586cm -1 and 1620cm -1 The relative standard deviation (RSD) values ​​of the Raman peak intensities at the three-dimensional Ag / Al(OH) 3 / Al array structure has good uniformity when used as the substrate.

[0052] In order to further characterize the present invention as a detection of pesticide molecules, in this embodiment, a three-dimensional Ag / Al(OH) 3 / Al array structure as the substrate to detect pesticide standard solution, such as Figure 8As shown in (a), at 998 cm -1 、1408cm -1 and 1600cm -1 The characteristic peak of triazophos was observed at Figure 8 In (b), we can observe 1073cm -1 、1530cm -1 and 1580cm -1 The peak at is the characteristic peak of diquat. Figure 8 In (c), we can observe 998cm -1 、1023cm -1 、1071cm -1 and 1571cm -1 The peak value belongs to fonothion. At the same time, in this embodiment, the peak values ​​as low as 10 -7 M, 10 - 7 M and 10 -8 The trace concentrations of the three pesticides corresponding to M indicate that the SERS substrate has high detection sensitivity for pesticide molecules and is applicable in pesticide detection. In addition, this example also carried out detection of multi-component pesticide residues, and the results obtained are as follows: Fig. 9 As shown in (a), (b), (c) and (d), it is proved that this embodiment can accurately identify the Raman characteristic peaks of various pesticide components in the multi-component system, and further proves that this embodiment also has good detection and analysis capabilities for multi-component pesticide residues.

[0053] Embodiment 2

[0054] In this embodiment, the three-dimensional Ag / Al(OH) prepared in Example 1 is used. 3 / Al array structure as the substrate, 10μL polystyrene (PS) droplets were dropped on the hydrophobic surface for analysis, and the results were as follows Fig.10 As shown, Fig.10 (a), (b) and (c) show the -1 、1029cm -1 and 1598cm -1 The Raman peaks observed at 1000 cm -1 The peak at 1598 cm -1 The peak at 1029 cm is attributed to the asymmetric stretching vibration of carbon atoms in the benzene ring. -1 The peak at is related to the symmetric stretching vibration of the carbon atoms in the benzene ring. Therefore, based on the above content, the three-dimensional Ag / Al(OH) prepared in Example 1 3The Ag / Al array structure can detect PS microbeads of various sizes. It can also be found that even at a low concentration of 25 μg / mL, it can show high enrichment efficiency and sensitivity, which proves that the three-dimensional Ag / Al(OH) 3 When the / Al array structure is used as a SERS substrate, low concentrations of nanoplastics in water environments can be detected.

[0055] In summary, the three-dimensional Ag / Al(OH) 3 / Al array structure as the substrate, the detection limit of CV molecules is 10 -8 M, relative standard deviation value is less than 10%, and the detection concentration is less than 25 μg / ml for PS microspheres of different sizes.

[0056] Therefore, the above-mentioned three-dimensional Ag / Al(OH) 3 / Al sensor for pesticide residues and SERS sensing of micro-nano plastics, and the preparation of three-dimensional Ag / Al(OH) 3 The / Al array structure is used as the SERS substrate, and the surface plasmon resonance effect is used to significantly enhance the Raman signal, achieving high-sensitivity and high-uniformity detection of pesticide residues and micro-nano plastics, overcoming the shortcomings of traditional Raman technology such as weak signal and poor uniformity, and providing an effective analytical means for food safety and environmental protection.

[0057] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0058] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor, characterized in that: The following steps are involved: Based on the hydrothermal method, aluminum hydroxide nanosheets are prepared, and the aluminum hydroxide nanosheets are subjected to an amination treatment; Forming a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheet after the amination treatment to obtain an AuNPs-functionalized aluminum hydroxide nanosheet; The AuNPs-functionalized aluminum hydroxide nanosheets are immersed in a mixed solution containing silver ions, the silver ions are reduced by a reducing agent, and silver nanoparticles AgNPs are deposited on the surface of the AuNPs-functionalized aluminum hydroxide nanosheets to obtain a three-dimensional Ag / Al(OH)3 / Al array structure; The three-dimensional Ag / Al(OH)3 / Al array structure is used as a substrate of a SERS sensor to detect pesticide residues and micro-nano plastics.

2. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 1, characterized in that: Based on the hydrothermal method, the process of preparing aluminum hydroxide nanosheets is as follows: select aluminum foil, clean and cut the aluminum foil, then mix the treated aluminum foil with an alkaline solution to form a slurry, put the slurry into a stainless steel reactor, and place it in a hydrothermal reaction equipment for heating reaction treatment; after the reaction is completed, the stainless steel reactor is naturally cooled to room temperature, the reaction product is taken out, filtered and washed with deionized water, and dried to obtain aluminum hydroxide nanosheets.

3. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 2, characterized in that: The process of amination treatment of the aluminum hydroxide nanosheets is as follows: at room temperature, the aluminum hydroxide nanosheets are immersed in an ethylenediamine ethanol solution, the concentration of the ethylenediamine ethanol is 25 vol%, and the immersion time is 2 hours, the surface of the aluminum hydroxide nanosheets is amination treated, and the surface is cleaned with ethanol after the treatment.

4. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 1, characterized in that: The process of forming a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheet after the amination treatment to obtain the aluminum hydroxide nanosheet functionalized with AuNPs is as follows: immersing the aluminum hydroxide nanosheet after the amination treatment in a 0.1wt% chloroauric acid solution for 2 hours, wherein the aluminum hydroxide nanosheet after the amination treatment interacts with the gold precursor through the amino group, and the gold precursor is adsorbed on the surface of the aluminum hydroxide nanosheet; then immersing the aluminum hydroxide nanosheet loaded with the gold precursor in a sodium borohydride aqueous solution for 2 minutes, reducing the gold precursor to gold atoms, and forming a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheet, and finally rinsing with deionized water and ethanol to remove unreacted reducing agent and unadsorbed gold precursor, and drying to obtain the aluminum hydroxide nanosheet functionalized with AuNPs.

5. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 1, characterized in that: The mixed solution containing silver ions is prepared from deionized water, silver nitrate solution and ethylenediaminetetraacetic acid solution. The concentration of the silver nitrate solution is 100 mM, and the concentration of the ethylenediaminetetraacetic acid solution is 50 mM.

6. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 5, characterized in that: The preparation process of the mixed solution containing silver ions is as follows: 5 ml of silver nitrate solution and 5 ml of ethylenediaminetetraacetic acid solution are added to 10 ml of deionized water, and magnetic stirring is performed for 15 minutes to obtain the mixed solution containing silver ions.

7. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 6, characterized in that: The process of reducing silver ions by a reducing agent and depositing silver nanoparticles AgNPs on the surface of the AuNPs-functionalized aluminum hydroxide nanosheets to obtain a three-dimensional Ag / Al(OH)3 / Al array structure is as follows: immersing the AuNPs-functionalized aluminum hydroxide nanosheets in the mixed solution containing silver ions, then adding 5 ml of the reducing agent and stirring until the silver nanoparticles AgNPs are uniformly deposited, and finally rinsing with deionized water and drying to obtain the three-dimensional Ag / Al(OH)3 / Al array structure.

8. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 7, characterized in that: The reducing agent is L-ascorbic acid, and the concentration is 25 mM.

9. The SERS sensing method for pesticide residues and micro-nano plastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 1, characterized in that: The three-dimensional Ag / Al(OH)3 / Al array structure is used as the substrate of SERS sensor to detect pesticide residues and micro-nano plastics, including: using the three-dimensional Ag / Al(OH)3 / Al array structure as the substrate, the detection limit of CV molecules is 10 -8 M, relative standard deviation value is less than 10%, and the detection concentration is less than 25 μg / ml for PS microspheres of different sizes.

Images