A method for rapid enrichment and detection of nanoplastics based on a condensed microdroplet SERS platform

Abstract

A method for rapid enrichment and detection of nanoplastics based on a condensate micro-droplet SERS platform relates to a method for rapid enrichment and detection of nanoplastics. The present invention aims to solve the problem that there is currently no method for detecting substances by combining SERS technology with condensates having enrichment properties. The present invention specifically includes step 1, synthesizing silver sol; step 2, preparing condensates; step 3, preparing a condensate SERS platform; adding the silver sol obtained in step 1 to the condensate solution obtained in step 3 and vortexing to obtain a condensate micro-droplet SERS substrate with silver nanoparticles captured; step 4, detecting nanoplastics; adding a polystyrene microsphere solution to the condensate droplet SERS platform obtained in step 3 and vortexing for 10 seconds, and then performing SERS measurement. The present invention belongs to the technical field of hydrophobic pollutant detection.

Description

Technical Field

[0001] The invention relates to a method for rapid enrichment and detection of nanoplastics, belonging to the technical field of hydrophobic pollutant detection. Background Art

[0002] In recent years, plastic pollution has become one of the most pressing environmental issues, seriously affecting human health. Nano-scale plastic particles have structural stability and a large specific surface area, providing abundant adsorption sites for pollutants in the environment. Their high hydrophobicity makes them an effective carrier for transporting various persistent organic pollutants. Effective technology for detecting nanoplastics is a necessary prerequisite for protecting human health and ecological safety. Among the existing methods for detecting nanoplastics, mass spectrometry is a destructive detection method that will damage the sample. Infrared methods are sensitive to water molecules and are not suitable for water environment detection. Raman spectroscopy is fast and simple to operate and will not cause damage to the object being tested. However, the direct use of ordinary Raman spectroscopy in water detection is not sensitive enough. Surface-enhanced Raman spectroscopy (SERS) methods need to be introduced to prepare a variety of SERS composite substrates for the detection of nanoplastics. However, the preparation of composite substrates is difficult and expensive, which increases the time cost of detection. The preparation method of metal sol SERS substrates is simple and inexpensive. Agglomerates are a liquid-liquid phase separation phenomenon that has the ability to enrich substances from the surrounding environment, increase the local concentration of substances, and improve the detection limit. The formation of aggregates achieves simultaneous enrichment of the SERS substrate and the detected species, but research on detecting substances using this method has not yet been reported. Summary of the Invention

[0003] The present invention aims to solve the problem that there is currently no method for detecting substances by combining SERS technology with condensates with enrichment properties, and further proposes a method for rapid enrichment and detection of nanoplastics based on a condensate microdroplet SERS platform.

[0004] The technical solution adopted by the present invention to solve the above problems is: the steps of the present invention include:

[0005] Step 1, synthesizing silver sol;

[0006] Step 2, preparing agglomerates;

[0007] Step 3, preparing a condensate SERS platform; adding the silver sol obtained in step 1 to the condensate solution obtained in step 3 and vortexing to obtain a condensate micro-droplet SERS substrate with silver nanoparticles captured;

[0008] Step 4: Detect nanoplastics; add the polystyrene microsphere solution to the condensate droplet SERS platform obtained in step 3 and vortex for 10 seconds before performing SERS measurement.

[0009] Furthermore, step 1 specifically includes:

[0010] Step 101: Heat the silver nitrate solution to a slight boil while stirring;

[0011] Step 102: Add 1% by mass of a trisodium citrate aqueous solution, keep boiling, and continue stirring for 1 hour until the color changes from gray-green to gray-white;

[0012] Step 103: Cool the solution to room temperature while stirring to obtain a silver sol.

[0013] Furthermore, step 2 specifically includes:

[0014] Step 201, preparing a polydiallyl dimethyl ammonium chloride solution: dissolving polydiallyl dimethyl ammonium chloride in a phosphate buffer solution to prepare a 1-10 mg / mL polydiallyl dimethyl ammonium chloride solution;

[0015] Step 202, preparing a polyacrylic acid solution: dissolving polyacrylic acid in a phosphate buffer solution to prepare a 1-10 mg / mL polyacrylic acid solution;

[0016] Step 203: Add the solution prepared in step 201 to the solution prepared in step 202, and oscillate using a vortex shaker for 20 to 30 seconds to obtain an aggregate.

[0017] Furthermore, the amounts of the substances in step 1 are in the following proportions: 0.036 g of silver nitrate is dissolved in 200 mL of deionized water; and 4 mL of a 1% sodium citrate aqueous solution is dissolved in 4 mL of a 1% sodium citrate aqueous solution.

[0018] Furthermore, the pH of the phosphate buffer solution in step 2 is 8.0.

[0019] Furthermore, in step 2, the concentration of the aqueous solution of polydiallyldimethylammonium chloride is 1 to 10 mg / mL, and the concentration of the aqueous solution of polyacrylic acid is 1 to 10 mg / mL.

[0020] Furthermore, in step 203 , the volume ratio of the polydiallyl dimethyl ammonium chloride solution to the polyacrylic acid solution is 2:1.

[0021] Furthermore, the amounts of the substances in step 3 are in the following proportions: 10 μL of polydimethylammonium chloride solution, 5 μL of polyacrylic acid solution, and 8 μL of silver sol.

[0022] Furthermore, the amounts of the substances in step 4 were in the following proportions: 2 μL of polystyrene microsphere solutions of different concentrations and 23 μL of coacervate solution.

[0023] Furthermore, in step 4, the continuous SERS measurement was performed with a data acquisition time of 10 s, accumulated once, and a power of 10 mW.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention constructs a SERS detection platform for aggregates with enrichment performance, which is simple to operate and highly efficient;

[0026] 2. The enrichment process of the SERS substrate and the substance to be detected can be completed within 1 minute, and the processing time is short;

[0027] 3. The linear range of the polystyrene nanoplastic of the present invention is 5×10 -8 g / L~0.5g / L (0.05ppb~500ppm), low detection limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is an optical microscope image of the agglomerate obtained in Example;

[0029] Figure 2 is a dark field microscope image of the aggregate obtained in Example;

[0030] Figure 3 is an optical microscope image of the aggregate SERS platform obtained in Example;

[0031] Figure 4 is a dark field microscope image of the condensate SERS platform obtained in Example;

[0032] Figure 5 is a graph showing the SERS intensity of the nanoplastics of the embodiment as a function of concentration;

[0033] Figure 6 is a linear relationship diagram of the SERS intensity and concentration ratio of the nanoplastics in the embodiment;

[0034] Figure 7 is a schematic diagram of the SERS spectrum of polystyrene microspheres;

[0035] Figure 8 It is a schematic diagram of the linear relationship between the intensity ratio and the logarithm of the concentration. Example

[0036] Example 1:

[0037] 1. Synthesis of Silver Sol

[0038] 0.036 g of AgNO3 was dissolved in 200 ml of deionized water and heated in an oil bath with stirring until slightly boiling (slight bubbling occurred without stirring. After bubbling began, the oil bath temperature was slightly lowered to prevent violent boiling). 4 mL of a 1% sodium citrate aqueous solution was then quickly added and stirred at 100°C until the solution turned gray-green. Stirring and heating at 85°C for 1 hour until the color turned gray-white were continued. The solution was cooled to room temperature with stirring to obtain a silver sol.

[0039] 2. Preparation of Agglomerates

[0040] Preparation of polydiallyl dimethyl ammonium chloride solution: dissolve 10 mg of polydiallyl dimethyl ammonium chloride in 1 mL of phosphate buffer solution to prepare a 10 mg / mL polydiallyl dimethyl ammonium chloride solution;

[0041] Wherein, the concentration of phosphate buffer solution is 0.05 mol / L, and the pH is 8.0;

[0042] Preparation of polyacrylic acid solution: dissolve 10 mg of polyacrylic acid in 1 mL of phosphate buffer solution to prepare a 10 mg / mL polyacrylic acid solution;

[0043] Wherein, the concentration of phosphate buffer solution is 0.05 mol / L, and the pH is 8.0;

[0044] 10 μL of the polydimethylammonium chloride solution was added to 5 μL of the polyacrylic acid solution, and the mixture was vortexed for 30 seconds to obtain a coacervate solution.

[0045] like Figure 1 As shown, it can be seen that the condensate is a spherical droplet with regular shape;

[0046] like Figure 2 As shown, it can be seen that the interior of the condensate is hollow;

[0047] 3. Construction of the Condensate SERS Platform

[0048] During the agglomerate preparation process in step 2, 8 μL of the silver sol solution synthesized in step 1 was added and vortexed for 30 seconds to obtain an agglomerate micro-droplet SERS detection platform enriched with silver nanoparticles;

[0049] like Figure 3 As shown, it can be seen that silver nanoparticles have been successfully enriched inside the aggregates, the color of the aggregates becomes darker, and the contrast increases;

[0050] like Figure 4 As shown, bright spots originating from silver nanoparticles appeared inside the agglomerates, indicating the successful enrichment of silver nanoparticles.

[0051] 4. Detection of Nanoplastics at Different Concentrations

[0052] The polystyrene microsphere stock solution with an initial concentration of 0.5 g / L and a particle size of 20 nm was diluted with water step by step to obtain polystyrene microsphere solutions with different concentrations (0.5 g / L~5×10 -8 g / L);

[0053] 2 μL of polystyrene microsphere solutions of different concentrations were added to 23 μL of freshly prepared condensate SERS platform solution and vortexed for 10 seconds to obtain condensate microdroplets enriched with polystyrene microspheres. Continuous SERS measurements were then immediately performed.

[0054] The data acquisition time was 10 s, accumulated once, and the power was 10 mW. The instrument used was a confocal micro-Raman spectrometer (RTS2-301-DL) purchased from Beijing Zhuoli Hanguang Instrument Co., Ltd.;

[0055] like Figure 5 As shown, it can be seen that granular substances appear inside the agglomerates, indicating that the polystyrene microspheres are successfully enriched inside the agglomerates;

[0056] like Figure 6 As shown in the figure, it can be seen that the SERS signal of the polystyrene microspheres inside the aggregate is higher than that outside the aggregate, indicating that the polystyrene microspheres are effectively enriched inside the aggregate;

[0057] like Figure 7 As shown, the concentration range is 0.5g / L~5×10 -8 SERS spectra of polystyrene microspheres with a concentration of 500 ppm to 0.05 ppb, where 1004 cm -1 The ratio of peak intensities varies with concentration;

[0058] like Figure 8 As shown, 1004cm -1 There is a linear relationship between the intensity ratio and the logarithm of the concentration, and the regression coefficient is (R 2 =0.975).

[0059] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for rapid enrichment and detection of nanoplastics based on a condensed microdroplet SERS platform, characterized in that: Specifically include: Step 1, synthesizing silver sol; Step 2: preparing the aggregate; specifically comprising: Step 201, preparing a polydiallyl dimethyl ammonium chloride solution: dissolving polydiallyl dimethyl ammonium chloride in a phosphate buffer solution to prepare a 1-10 mg / mL polydiallyl dimethyl ammonium chloride solution; Step 202, preparing a polyacrylic acid solution: dissolving polyacrylic acid in a phosphate buffer solution to prepare a 1-10 mg / mL polyacrylic acid solution; Step 203: adding the solution prepared in step 201 to the solution prepared in step 202, and vortexing for 20 to 30 seconds to obtain an aggregate; The volume ratio of polydiallyldimethylammonium chloride solution to polyacrylic acid solution is 2:1; Step 3, preparing a condensate SERS platform; adding the silver sol obtained in step 1 to the condensate solution obtained in step 3 and vortexing to obtain a condensate micro-droplet SERS substrate with silver nanoparticles captured; Step 4: Detect nanoplastics; add the polystyrene microsphere solution to the condensate droplet SERS platform obtained in step 3 and vortex for 10 seconds before performing SERS measurement.

2. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: Step 1 specifically includes: Step 101: Heat the silver nitrate solution to a slight boil while stirring; Step 102: Add 1% by mass of a trisodium citrate aqueous solution, keep boiling, and continue stirring for 1 hour until the color changes from gray-green to gray-white; Step 103: Cool the solution to room temperature while stirring to obtain a silver sol.

3. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: The amounts of each substance in step 1 are in the following proportions: 0.036 g silver nitrate is dissolved in 200 mL deionized water; 4 mL of a 1% sodium citrate aqueous solution is dissolved in 4 mL of a 1% sodium citrate aqueous solution.

4. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: The pH of the phosphate buffer solution in step 2 is 8.

0.

5. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: In step 2, the concentration of the polydiallyldimethylammonium chloride aqueous solution is 1-10 mg / mL, and the concentration of the polyacrylic acid solution aqueous solution is 1-10 mg / mL.

6. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: The amounts of each substance used in step 3 are in the following proportions: 10 μL polydimethylammonium chloride solution, 5 μL polyacrylic acid solution, and 8 μL silver sol.

7. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: The amounts of each substance used in step 4 were in the following proportions: 2 μL of polystyrene microsphere solutions of different concentrations and 23 μL of aggregate solution.

8. The method for rapid enrichment and detection of nanoplastics based on the aggregate microdroplet SERS platform according to claim 1, characterized in that: In step 4, the continuous SERS measurement was performed with a data acquisition time of 10 s, one accumulation, and a power of 10 mW.

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