SERS sensing method for pesticide residues and micro-nanoplastics based on three-dimensional Ag / Al(OH)3 / Al sensor

Abstract

The present invention provides a SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor, belonging to the field of analytical chemistry technology. The method comprises: preparing aluminum hydroxide nanosheets based on a hydrothermal method and performing an amination treatment on the aluminum hydroxide nanosheets; forming a gold nanoparticle AuNPs seed layer on the amination-treated aluminum hydroxide nanosheets to obtain AuNPs-functionalized aluminum hydroxide nanosheets; then immersing the aluminum hydroxide nanosheets 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 aluminum hydroxide nanosheets to obtain a three-dimensional Ag / Al(OH)3 / Al array structure; and using the three-dimensional Ag / Al(OH)3 / Al array structure as a substrate for a SERS sensor to detect pesticide residues and micro-nanoplastics. The present invention prepares a periodic array substrate with a uniform structure, achieves excellent SERS performance, effectively overcomes the uniformity limitations of traditional Raman technology, and significantly improves the detection effect of pesticide residues and micro-nanoplastics.

Description

Technical Field

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

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

[0003] Surface-enhanced Raman scattering (SERS) technology is a powerful analytical tool that 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] Despite the enormous potential of SERS technology, practical applications still face challenges. The uneven distribution of metal nanoparticles on the SERS substrate leads to spatially uneven amplification, which in turn affects the reproducibility of the SERS signal. Furthermore, the stronger the enhancement, the smaller the hotspot, and the lower the probability of detecting the hotspot, making SERS difficult to widely apply in practical detection. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor. A periodic array substrate with a uniform structure is prepared to achieve excellent SERS performance, effectively overcoming the limitations of traditional Raman technology in uniformity, thereby significantly improving the detection effect of pesticide residues and micro-nanoplastics.

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

[0007] A SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor comprises the following steps:

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

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

[0010] Immersing the AuNPs-functionalized aluminum hydroxide nanosheets 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 nanosheets 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 the SERS sensor to detect pesticide residues and micro-nano plastics.

[0012] Preferably, the process for preparing aluminum hydroxide nanosheets based on the hydrothermal method is as follows: aluminum foil is selected and cleaned and cut, the treated aluminum foil is then mixed with an alkaline solution to form a slurry, the slurry is loaded into a stainless steel reactor, and placed 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.

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

[0014] Preferably, a gold nanoparticle AuNPs seed layer is formed on the aluminum hydroxide nanosheets after amination treatment to obtain AuNPs-functionalized aluminum hydroxide nanosheets. The process is as follows: immersing the aluminum hydroxide nanosheets after amination treatment in a 0.1wt% chloroauric acid solution for 2 hours, wherein the aluminum hydroxide nanosheets after amination treatment interact with the gold precursor through the amino group, and the gold precursor is adsorbed on the surface of the aluminum hydroxide nanosheets; then immersing the aluminum hydroxide nanosheets 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 nanosheets. Finally, rinsing with deionized water and ethanol to remove unreacted reducing agent and unadsorbed gold precursor, and drying to obtain AuNPs-functionalized aluminum hydroxide nanosheets.

[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: 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.

[0017] Preferably, 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 process 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.

[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 is used as a substrate for SERS sensor to detect pesticide residues and micro-nano plastics, including: using the three-dimensional Ag / Al(OH)3 / Al array structure as a 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 25μg / ml 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 / Al array structure as a SERS substrate by uniformly depositing silver nanoparticles on aluminum hydroxide nanosheets. The surface plasmon resonance effect is used to significantly enhance the Raman signal, achieving highly sensitive and highly uniform detection of pesticide residues and micro-nanoplastics. This overcomes the shortcomings of traditional Raman technology such as weak signals and poor uniformity, and provides an effective analytical method 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 following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0023] Figure 1 This is a flow chart of the SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor of the present invention;

[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, (b) represents an image of Al(OH)3 nanosheets, (c) represents an image of three-dimensional Ag / Al(OH)3 / Al, and (d) represents a SERS detection image;

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

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

[0027] Figure 5 SEM images of three-dimensional Ag / Al(OH)3 / Al structures prepared with different concentrations of AgNO3 provided in Example 1 of the present invention; wherein (a) represents the SEM image with a concentration of 25 mM, (b) represents the SEM image with a concentration of 50 mM, (c) represents the SEM image with a concentration of 100 mM, and (d) represents the SEM image with a concentration of 200 mM;

[0028] Figure 6 SERS spectra of CV adsorbed on the three-dimensional Ag / Al(OH)3 / Al structure prepared according to Example 1 of the present invention; wherein (a) represents SERS spectra at different reaction times, (b) represents SERS spectra at different AgNO3 concentrations, and (c) represents SERS spectra at different treatment processes;

[0029] Figure 7The performance test data of the three-dimensional Ag / Al(OH)3 / Al structure as the SERS substrate provided in Example 1 of the present invention; wherein (a) shows the SERS spectra obtained by CV at different concentrations adsorbed on the Al(OH)3 / Ag substrate, (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 values ​​at

[0030] Figure 8 These are 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 triazophos, (b) represents the SERS spectrum corresponding to diquat, and (c) represents the SERS spectrum corresponding to fonofos.

[0031] Figure 9 The 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 fonothion, 10 -6 M's Diquat and 10 -7 M's triazophos;

[0032] Figure 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 clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts 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] Example 1

[0036] Reference Figure 1 The present invention provides a SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor, comprising 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 nanosheets after the amination treatment to obtain AuNPs-functionalized aluminum hydroxide nanosheets;

[0039] Step 300: immersing the AuNPs-functionalized aluminum hydroxide nanosheets 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 nanosheets to obtain a three-dimensional Ag / Al(OH)3 / Al array structure;

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

[0041] In step 100, the hydrothermal method for preparing aluminum hydroxide nanosheets involves the following steps: selecting aluminum foil, cleaning and cutting the foil, mixing the treated aluminum foil with an alkaline solution to form a slurry, placing the slurry in a stainless steel reactor, and placing it in a hydrothermal reaction apparatus for heating and reaction. After the reaction, the reactor is naturally cooled to room temperature, the reaction product is removed, filtered and washed with deionized water, and dried to obtain aluminum hydroxide nanosheets. The aluminum hydroxide nanosheets are then subjected to amination treatment by immersing the aluminum hydroxide nanosheets in an ethylenediamine ethanol solution at a concentration of 25 vol% for 2 hours at room temperature to aminize the surface of the aluminum hydroxide nanosheets. After the treatment, the surface is rinsed with ethanol.

[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, and the gold precursor is adsorbed 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, the gold precursor is reduced to gold atoms, and a gold nanoparticle AuNPs seed layer is formed on the aluminum hydroxide nanosheets. Finally, the aluminum hydroxide nanosheets are rinsed with deionized water and ethanol to remove unreacted reducing agent and 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 EDTA solution. The concentration of the silver nitrate solution is 100 mM, and the concentration of the EDTA solution is 50 mM. The mixed solution containing silver ions is prepared by adding 5 ml of the silver nitrate solution and 5 ml of the EDTA solution to 10 ml of deionized water, and magnetically stirring for 15 minutes to obtain the mixed solution containing silver ions.

[0044] In step 400, silver ions are reduced by a reducing agent, and silver nanoparticles (AgNPs) are deposited on the surface of AuNPs-functionalized aluminum hydroxide nanosheets to form a three-dimensional Ag / Al(OH)3 / Al array structure. The process includes immersing the AuNPs-functionalized aluminum hydroxide nanosheets in a mixed solution containing silver ions, adding 5 ml of a reducing agent, and stirring until the silver nanoparticles (AgNPs) are uniformly deposited. Finally, the solution is rinsed with deionized water and dried to form a three-dimensional Ag / Al(OH)3 / Al array structure. The reducing agent is L-ascorbic acid at a concentration of 25 mM.

[0045] Based on the above, the preparation and characterization process of the three-dimensional Ag / Al(OH)3 / Al array structure as a SERS substrate is as follows Figure 2 As shown. Figure 2 Comparing the images in (a), (b), and (c), we can see that silver nanoparticles are uniformly and densely modified on aluminum hydroxide nanosheets using 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, the characteristic peak of Al(OH)3 is clearly displayed, while the Raman peak of aluminum hydroxide nanosheets disappears after surface modification with silver nanoparticles. Figure 3(a) shows the XRD pattern of the substrate. The diffraction peak at 38.1° is attributed to the (111) crystal plane of face-centered cubic (fcc) silver, indicating that silver nanoparticles have been successfully decorated on the surface of aluminum hydroxide nanosheets through the seed-mediated method. In addition, the EDS elemental map of Ag / Al(OH)3 shows that AgNPs have been successfully decorated on the Al(OH)3 substrate, as shown in Figure 2. Figure 3 (c) shown.

[0046] In order to further characterize the formation of the three-dimensional Ag / Al(OH)3 / Al array structure, this example conducted a time-dependent experiment at a silver nitrate concentration of 50 mM to determine the optimal time for the array structure. The results are shown in Figure 2. Figure 4 As shown in Figure 2, 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, indicating 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, as shown in Figure 2. 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); and Ag / Al(OH)3 nanosheet arrays with densely distributed AgNPs were obtained within 7 minutes, as shown in Figure 4 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 (c). Figure 4 As shown in (d) in the figure, the size of the Ag nanoparticles continues to grow with increasing deposition time, while the interparticle gaps between adjacent nanoparticles decrease accordingly. These results demonstrate that the size and interparticle gaps of Ag nanoparticles can be controlled by adjusting the growth deposition time, and that periodic, uniform, three-dimensional Ag / Al(OH)3 / Al array structures can be rapidly synthesized within 7 minutes at room temperature.

[0047] Also refer to Figure 5 , at a low AgNO3 concentration of 25 mM, many smaller-sized silver nanoparticles were evenly distributed on the aluminum hydroxide nanosheets, e.g. Figure 5 As shown in (a) in the figure, with the increase of AgNO3 concentration, the diameter of silver nanoparticles becomes larger, as shown in 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 performance of the three-dimensional Ag / Al(OH)3 / Al array structure as a SERS substrate, the amination process also plays a vital role in the formation of the three-dimensional Ag / Al(OH)3 / Al array structure. When the aluminum hydroxide nanosheets are not aminated or chloroauric acid is used instead of silver nitrate, under the same conditions, the 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 SERS spectra of crystal violet (CV) adsorbed on the substrate of the three-dimensional Ag / Al(OH)3 / Al array structure prepared at different AgNO3 concentrations. It can be observed from the figure that the SERS intensity increases with the increase of AgNO3 concentration. At an AgNO3 concentration of 100mM, uniform and dense silver nanoparticles are deposited on the surface of the aluminum hydroxide nanosheets, which helps to generate a uniform SERS signal. When the AgNO3 concentration exceeds 100mM, some excess Ag nanoparticles are deposited on the surface of the initial Ag-aluminum hydroxide nanosheets.

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

[0050] Finally, based on the above information, the optimal conditions for preparing a three-dimensional Ag / Al(OH)3 / Al array with excellent SERS performance were determined by adjusting experimental parameters to effectively control the size of the Ag nanoparticles and the gaps between adjacent Ag nanoparticles. Experiments were conducted to identify the substrate with the highest sensitivity. In this example, a three-dimensional Ag / Al(OH)3 / Al array prepared by amination was selected, with an AgNO3 concentration of 100 mM.

[0051] After determining the optimal technical solution for the three-dimensional Ag / Al(OH)3 / Al array structure, in this example, CV was used as a model probe molecule to evaluate the SERS performance of the three-dimensional Ag / Al(OH)3 / Al array structure as a 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 the Ag / Al(OH)3 / Al substrate is immersed for 10 -5When the CV solution of M was added, the SERS spectra were recorded using a portable Raman spectrometer, such as Figure 7 (b), (c), (e), (f), and (g) are shown in Fig. -1 、1172cm -1 、1586cm -1 and 1620cm -1 The relative standard deviations (RSDs) of the Raman peak intensities at 100 nm and 100 nm were 8.3%, 5.6%, 7.4%, and 6.4%, respectively. The RSD value of the substrate was less than 10%, indicating that the three-dimensional Ag / Al(OH)3 / Al array structure had good uniformity when used as a substrate.

[0052] In order to further characterize the utility of the present invention for the detection of pesticide molecules, in this embodiment, a three-dimensional Ag / Al(OH)3 / Al array structure was used as a substrate to detect a pesticide standard solution, such as Figure 8 As shown in (a), at 998cm -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 fonophos. At the same time, in this embodiment, the peak value 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 sensitivity to pesticide molecules and is applicable in pesticide detection. In addition, this example also conducted a multi-component pesticide residue detection, and the results obtained are as follows: Figure 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 prove that this embodiment also has good detection and analysis capabilities for multi-component pesticide residues.

[0053] Example 2

[0054] In this example, the three-dimensional Ag / Al(OH)3 / Al array structure prepared in Example 1 was used as a substrate, and 10 μL of polystyrene (PS) droplets were dropped on the hydrophobic surface for analysis. The results were as follows: Figure 10 As shown, Figure 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 corresponds to the breathing vibration of the benzene ring. -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, the three-dimensional Ag / Al(OH)3 / Al array structure prepared in Example 1 is capable of detecting PS microbeads of various sizes. Furthermore, it can be found that even at a low concentration of 25 μg / mL, it exhibits high enrichment efficiency and sensitivity, further demonstrating that the three-dimensional Ag / Al(OH)3 / Al array structure of the present invention can be used as a SERS substrate to detect low-concentration nanoplastics in aqueous environments.

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

[0056] Therefore, the above-mentioned SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor was adopted to prepare a three-dimensional Ag / Al(OH)3 / Al array structure as a SERS substrate. The surface plasmon resonance effect was used to significantly enhance the Raman signal, achieving high-sensitivity and high-uniformity detection of pesticide residues and micro-nanoplastics, 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] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A SERS sensing method for pesticide residues and micro-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor, characterized in that: The following steps are involved: Aluminum hydroxide nanosheets are prepared based on a hydrothermal method, and the aluminum hydroxide nanosheets are subjected to an amination treatment; forming a gold nanoparticle AuNPs seed layer on the aluminum hydroxide nanosheets after the amination treatment to obtain AuNPs-functionalized aluminum hydroxide nanosheets; Immersing the AuNPs-functionalized aluminum hydroxide nanosheets 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 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 the substrate of the SERS sensor to detect pesticide residues and micro-nano plastics.

2. The SERS sensing method for pesticide residues and micro-nanoplastics 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 for preparing aluminum hydroxide nanosheets is as follows: aluminum foil is selected and 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 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-nanoplastics 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 with a concentration of 25 vol% and an immersion time of 2 h, the surface of the aluminum hydroxide nanosheets is aminated, and the surface is washed with ethanol after the treatment.

4. The SERS sensing method for pesticide residues and micro-nanoplastics 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 AuNPs-functionalized aluminum hydroxide nanosheet is as follows: soaking the aluminum hydroxide nanosheet after the amination treatment 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, and the gold precursor is adsorbed on the surface of the aluminum hydroxide nanosheet; then soaking 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; finally, rinsing with deionized water and ethanol to remove unreacted reducing agent and unadsorbed gold precursor, and drying to obtain the AuNPs-functionalized aluminum hydroxide nanosheet.

5. The SERS sensing method for pesticide residues and micro-nanoplastics 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-nanoplastics 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-nanoplastics based on a three-dimensional Ag / Al(OH)3 / Al sensor according to claim 6, characterized in that: 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 process 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-nanoplastics 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 with a concentration of 25 mM.

9. The SERS sensing method for pesticide residues and micro-nanoplastics 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 25μg / ml PS microspheres of different sizes.

Images