Fluorescent micro-nano plastic microspheres as well as preparation method and application thereof
Fluorescent micro/nanoplastics were prepared by a tetrahydrofuran and methanol composite swelling method, which solved the problems of low fluorescence intensity and poor stability in the existing technology. This method enables the preparation of efficient and stable fluorescent micro/nanoplastics, which are suitable for imaging tracing and toxicology studies.
Patent Information
- Application Number
- CN202511449117.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-11
- Publication Date
- 2026-02-27
AI Technical Summary
Existing methods for preparing fluorescent micro/nanoplastics suffer from problems such as low fluorescence intensity, poor stability, complex operation, and unsuitability for large-scale production. In particular, fluorescent microspheres prepared by the swelling method have unstable fluorescence performance under external environmental interference.
A swelling method using tetrahydrofuran and methanol composite swelling agents was employed. Fluorescent dyes were embedded inside polymer microspheres through ultrasonic mixing and stirring. Organic reagents were then removed by vacuum distillation, and the microspheres were washed until no fluorescent residue remained, thus preparing fluorescent micro/nanoplastics.
The prepared fluorescent micro/nanoplastics have high fluorescence intensity and good stability, and the surface dye is not easily detached. They are suitable for imaging tracing and toxicology studies. The process is simple, the cost is low, and they are applicable to a variety of polymer materials.
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Figure CN121574407A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a fluorescent micro / nanoplastics microsphere, its preparation method and application, belonging to the field of micro / nanoplastics labeling technology. Background Technology
[0003] Imaging and quantitative analysis of micro / nanoplastics are fundamental to assessing their environmental and health risks. Current mainstream methods are mainly divided into two categories: label-free analysis and labeled tracer methods. Label-free analysis methods, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, rely on the chemical bond vibration signals of microplastic nuclei (MNPs), making it difficult to distinguish background interference from biological tissues. While pyrolysis gas chromatography-mass spectrometry (Py-GC / MS) can quantitatively analyze MNPs, it cannot achieve in-situ spatial imaging. Labeled tracer methods, especially fluorescent probe-labeled tracer methods, have advantages such as high sensitivity and ease of operation, and are therefore widely used in the field of imaging and tracer analysis of micro / nanoplastics.
[0004] Traditional methods for preparing fluorescently labeled micro / nanoplastics generally include embedding, bonding, adsorption, copolymerization, and swelling methods. Among these, fluorescent micro / nanoplastics prepared by surface modification methods such as adsorption and chemical bonding are susceptible to interference from the external environment, affecting the reliability of experimental results. In the copolymerization process, uneven dye molecule distribution and tendency to aggregate and induce quenching affect the fluorescence properties of the micro / nanoplastics. Furthermore, some processes are complex, time-consuming, and unsuitable for large-scale production.
[0005] The swelling method can embed fluorescent dyes inside the molecule by controlling the swelling-shrinkage dynamic process of micro and nano plastic polymer chains. It has the advantages of simple operation, easy control, and stable fluorescence performance. However, fluorescent microspheres prepared by the swelling method in the present technology still have problems such as low fluorescence intensity and poor stability. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a fluorescent micro / nanoplastics microsphere, its preparation method, and its application. The fluorescent micro / nanoplastics microsphere has no dye adhesion on its surface and exhibits high stability. The tetrahydrofuran and methanol composite swelling agents used in the preparation process have a synergistic effect, resulting in high fluorescence intensity. Furthermore, the process is simple to operate and highly controllable.
[0007] To achieve the above objectives, the following technical solution is provided: The first objective of this invention is to provide a method for preparing fluorescent micro / nanoplastics, the method comprising the following steps: (1) Disperse the polymer microspheres in an aqueous solution of sodium dodecyl sulfonate (SDS) and mix them by ultrasonication to obtain a polymer microsphere dispersion; (2) Add tetrahydrofuran to the polymer microsphere dispersion obtained in step (1), and mix by ultrasonication to obtain a mixture; (3) Add anhydrous methanol to the mixture obtained in step (2), then add fluorescent dye, stir to react, distill under reduced pressure after reaction, and wash to obtain the final product.
[0008] In one embodiment, the polymer microspheres in step (1) include one or more of polystyrene microspheres, polymethyl methacrylate microspheres, and UV-aged polystyrene microspheres.
[0009] In one embodiment, the mass fraction of sodium dodecyl sulfonate (SDS) in the aqueous solution of sodium dodecyl sulfonate (SDS) in step (1) is 0.25~0.5 wt%.
[0010] In one embodiment, the ratio of the polymer microspheres and sodium dodecyl sulfonate (SDS) aqueous solution in step (1) is 2~5:1~3, mg:mL.
[0011] In one embodiment, the ultrasonic conditions in step (1) are: power of 100~200 W and time of 5~10 min.
[0012] In one embodiment, the ratio of tetrahydrofuran to polymer microspheres in step (2) is 0.1~2.5:5; mL:mg; preferably 0.5~1.5:5; mL:mg.
[0013] In one embodiment, the volume ratio of anhydrous methanol to tetrahydrofuran is 1.25:0.1~2.5; preferably 1.25:0.5~1.5.
[0014] In one embodiment, the ratio of anhydrous methanol to polymer microspheres in step (3) is 1~5:5, mL:mg.
[0015] In one embodiment, the fluorescent dye in step (2) includes any one of Nile Red, Rhodamine B, and Tetraphenylethylene (TPE).
[0016] In one embodiment, the concentration of the fluorescent dye in step (2) is 0.5~3 mmol / L; more preferably 0.5~1.5 mmol / L.
[0017] In one embodiment, the mass ratio of the polymer microspheres to the fluorescent dye is 5:0.2~1.2, preferably 5:0.2~0.6.
[0018] In one embodiment, the stirring reaction in step (3) requires ultrasonic mixing to achieve uniformity. The ultrasonic conditions are: power of 100~200 W and time of 5~10 min.
[0019] In one embodiment, the temperature of the stirring reaction in step (3) is 0~45 ℃, preferably 25 ℃.
[0020] In one embodiment, the stirring reaction time in step (3) is 0.5 to 4 hours; preferably 1 to 2 hours.
[0021] In one embodiment, the vacuum distillation in step (3) is carried out at a temperature of 30-40 °C for 10-15 min.
[0022] In one embodiment, the washing in step (3) is specifically performed using anhydrous methanol until the supernatant shows no fluorescence at Ex / Em=552 nm / 585 nm.
[0023] A second objective of this invention is to provide a fluorescent micro / nanoplastics microsphere prepared by the method described above.
[0024] The third objective of this invention is to provide an application of the aforementioned fluorescent micro / nanoplastics in imaging tracing and toxicology studies.
[0025] A fourth objective of this invention is to provide a method for improving the fluorescence intensity and stability of fluorescent micro / nanoplastics, the method comprising the following steps: (1) Disperse the polymer microspheres in an aqueous solution of sodium dodecyl sulfonate (SDS) and mix them by ultrasonication to obtain a polymer microsphere dispersion; (2) Add tetrahydrofuran to the polymer microsphere dispersion obtained in step (1), and mix by ultrasonication to obtain a mixture; (3) Add anhydrous methanol to the mixture obtained in step (2), then add fluorescent dye, mix with ultrasound, stir and react, distill under reduced pressure to remove organic reagents, wash, and obtain the final product.
[0026] Beneficial effects: This invention provides a method for preparing fluorescent micro / nanoplastics based on a swelling method. Specifically, it utilizes a composite swelling agent (anhydrous methanol and tetrahydrofuran) to effectively open the internal cross-linked structure of polymer microspheres. Methanol acts as a co-solvent to promote the diffusion of Nile Red dye into the microspheres, thereby achieving efficient dye encapsulation. Simultaneously, the azeotropic effect and high volatility of tetrahydrofuran and methanol allow for rapid and complete removal of the organic solvent, restoring the microsphere structure and ultimately yielding fluorescent micro / nanoplastics microspheres with high fluorescence intensity and excellent stability. This method offers the following advantages over existing technologies: (1) The fluorescent micro-nanoplastics microspheres prepared by this invention have uniform size and small particle size variation; compared with other processes, they are simpler, lower in cost, and have higher application value. (2) When the same concentration of fluorescent dye is added, the fluorescent micro-nano plastic microspheres prepared by the present invention exhibit high fluorescence intensity; (3) The fluorescence stability of the fluorescent micro-nanoplastics prepared by this invention is significantly improved, and it has broad prospects for biological applications. After the surface of the microspheres is treated with nitric acid, there is no change in fluorescence intensity and emission wavelength, indicating that the dye is completely embedded inside the microspheres, which effectively reduces the shedding and leakage of fluorescent dye and ensures the stability of fluorescence signal. The microspheres have good stability in aqueous solution, and the fluorescence intensity does not change within 40 days. They can be used in imaging tracing, toxicology research and other fields, and have broad application prospects. (4) This method is applicable to a variety of polymer materials and has been successfully applied to various microspheres such as polystyrene and aged polystyrene, with high fluorescence intensity. Attached Figure Description
[0027] Figure 1 This is a process flow diagram for the preparation of fluorescent micro / nano-plastic microspheres of the present invention; Figure 2 Scanning electron microscope (SEM) images of fluorescent micro / nanoplastic microspheres prepared in Example 1 and untreated nanoscale polystyrene microspheres; the left image is the untreated one, and the right image is the one from Example 1. Figure 3 The image shows fluorescence intensity data of the fluorescent micro / nanoplastics microspheres prepared in Example 1 and Comparative Examples 1-5. Figure 4 The graphs show the particle size variation and zeta potential variation of the fluorescent micro / nanoplastics microspheres prepared in Example 1. Figure 5 The graph shows the change in fluorescence intensity of the fluorescent micro / nanoplastics microspheres prepared in Example 1 over time in 0.1% SDS aqueous solution. Figure 6 The fluorescence spectrum of the fluorescent micro / nanoplastics microspheres prepared in Example 1 is shown. Detailed Implementation
[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The specific embodiments described below further illustrate the present invention.
[0029] The source of the materials involved in this invention: Polystyrene microspheres: Jiangsu Zhichuan Technology Co., Ltd. UV-aged polystyrene microspheres: Weigh 25 mg of the above polystyrene microspheres and disperse them in 1 mL of 0.1% SDS aqueous solution and 1 mL of H2O2 (30%); then add the mixed solution to a quartz bottle and expose it to ultraviolet light (60 W UVC lamp, with a maximum emission wavelength of 254 nm) at 300 rpm for 36 hours to obtain the product.
[0030] Example 1 A method for preparing polymer fluorescent micro / nanoplastics includes the following steps: (1) Weigh 5 mg of polystyrene microspheres and disperse them in 2.5 mL of 0.25 wt% sodium dodecyl sulfonate aqueous solution. Dissolve them completely by sonication for 5 min with an ultrasonic power of 110 W to obtain a polystyrene microsphere dispersion. (2) Add 0.5 mL of tetrahydrofuran to the mixed solution in step (2) and continue to mix by sonication to obtain a mixed solution; (3) Add 1.25 mL of anhydrous methanol to the polystyrene microsphere dispersion obtained in step (1), and then add 0.6 mg (1.5 mmol / L) Nile red fluorescent dye, sonicate for 10 min at an ultrasonic power of 110 W, and then stir at 25 °C for 2 h at a rate of 300 rpm to carry out the reaction. (4) After the reaction is complete, the solution is transferred to a heart-shaped flask and distilled under reduced pressure at 35 °C for 15 min to remove organic reagents. The remaining solution is washed repeatedly by centrifugation at 18500 g with anhydrous methanol until the supernatant is free of fluorescence. The precipitate is taken and resuspended in 0.1 wt% sodium dodecyl sulfate aqueous solution to obtain polymer fluorescent micro-nanoplastics.
[0031] Example 2 The only difference from Example 1 is that the amount of tetrahydrofuran added in step (3) is 0.1 mL, 0.5 mL, 1 mL, 1.5 mL, 2 mL, and 2.5 mL, respectively, the stirring time at 25 °C is 3 h, and the amount of Nile Red fluorescent dye added is 0.4 mg (1 mmol / L). All other parameters and conditions are the same as in Example 1.
[0032] Example 3 The only difference from Example 1 is that the stirring time at 25 °C in step (3) is 0.5 h, 1 h, 2 h, 3 h, and 4 h, respectively, and the amount of Nile Red fluorescent dye added is 0.4 mg (1 mmol / L). All other parameters and conditions are the same as in Example 1.
[0033] Example 4 The only difference from Example 1 is that the amount of Nile Red fluorescent dye added in step (2) is 0.2 mg, 0.4 mg, 0.8 mg, and 1.2 mg, respectively. All other parameters and conditions are the same as in Example 1.
[0034] Example 5 The only difference from Example 1 is that the stirring temperature in step (3) is 0 ℃, 35 ℃, and 45 ℃, respectively, while the other parameters and conditions are the same as in Example 1.
[0035] Comparative Example 1 A method for preparing polymer fluorescent micro / nanoplastics includes the following steps: (1) Weigh 5 mg of polystyrene microspheres and disperse them in 2.5 mL of 0.25 wt% sodium dodecyl sulfonate aqueous solution. Dissolve them completely by sonication for 5 min with an ultrasonic power of 110 W to obtain a polystyrene microsphere dispersion. (2) Add 0.5 mL of tetrahydrofuran to the mixed solution in step (2) and continue to mix by sonication to obtain a mixed solution; (3) Add 1.25 mL of anhydrous ethanol to the polystyrene microsphere dispersion obtained in step (1), and then add 0.6 mg (1.5 mmol / L) Nile red fluorescent dye. Sonicate for 10 min at an ultrasonic power of 110 W, and then stir at 25 °C for 2 h at a rate of 300 rpm. (4) After the reaction is complete, the solution is transferred to a heart-shaped flask and distilled under reduced pressure at 35 °C for 15 min to remove organic reagents. The remaining solution is washed repeatedly by centrifugation at 18500 g with anhydrous methanol until the supernatant is free of fluorescence. The precipitate is taken and resuspended in 0.1 wt% sodium dodecyl sulfate aqueous solution to obtain polymer fluorescent micro-nanoplastics.
[0036] Comparative Example 2 A method for preparing polymer fluorescent micro / nanoplastics includes the following steps: (1) Weigh 5 mg of polystyrene microspheres and disperse them in 2.5 mL of 0.25 wt% sodium dodecyl sulfonate aqueous solution. Dissolve them completely by sonication for 5 min with an ultrasonic power of 110 W to obtain a polystyrene microsphere dispersion. (2) Add 0.5 mL of tetrahydrofuran to the mixed solution in step (2) and continue to mix by sonication to obtain a mixed solution; (3) Add 1.25 mL of anhydrous acetone to the polystyrene microsphere dispersion obtained in step (1), then add 0.6 mg (1.5 mmol / L) Nile red fluorescent dye, sonicate for 10 min at an ultrasonic power of 110 W, and then stir at 25 °C for 2 h at a rate of 300 rpm to carry out the reaction. (4) After the reaction is complete, the solution is transferred to a heart-shaped flask and distilled under reduced pressure at 35 °C for 15 min to remove organic reagents. The remaining solution is washed repeatedly by centrifugation at 18500 g with anhydrous methanol until the supernatant is free of fluorescence. The precipitate is taken and resuspended in 0.1 wt% sodium dodecyl sulfate aqueous solution to obtain polymer fluorescent micro-nanoplastics.
[0037] Comparative Example 3 A method for preparing polymer fluorescent micro / nanoplastics includes the following steps: (1) Weigh 5 mg of polystyrene microspheres and disperse them in 2.5 mL of 0.25 wt% sodium dodecyl sulfonate aqueous solution. Dissolve them completely by sonication for 5 min with an ultrasonic power of 110 W to obtain a polystyrene microsphere dispersion. (2) Add 0.5 mL of tetrahydrofuran to the mixed solution in step (2) and continue to mix by sonication to obtain a mixed solution; (3) Add 1.25 mL of 0.25 wt% SDS aqueous solution to the polystyrene microsphere dispersion obtained in step (1), and then add 0.6 mg (1.5 mmol / L) Nile red fluorescent dye, sonicate for 10 min at an ultrasonic power of 110 W, and then stir at 25 °C for 2 h at a rate of 300 rpm to carry out the reaction; (4) After the reaction is complete, the solution is transferred to a heart-shaped flask and distilled under reduced pressure at 35 °C for 15 min to remove organic reagents. The remaining solution is washed repeatedly by centrifugation at 18500 g with anhydrous methanol until the supernatant is free of fluorescence. The precipitate is taken and resuspended in 0.1 wt% sodium dodecyl sulfate aqueous solution to obtain polymer fluorescent micro-nanoplastics.
[0038] Comparative Example 4 A method for preparing polymer fluorescent micro / nanoplastics includes the following steps: (1) Weigh 5 mg of polystyrene microspheres and disperse them in 2.5 mL of 0.25 wt% sodium dodecyl sulfonate aqueous solution. Dissolve them completely by sonication for 5 min with an ultrasonic power of 110 W to obtain a polystyrene microsphere dispersion. (2) Add 0.5 mL of acetone to the mixed solution in step (2) and continue to sonicate to obtain a mixed solution; (3) Add 1.25 mL of anhydrous methanol to the polystyrene microsphere dispersion obtained in step (1), and then add 0.6 mg (1.5 mmol / L) Nile red fluorescent dye, sonicate for 10 min at an ultrasonic power of 110 W, and then stir at 25 °C for 2 h at a rate of 300 rpm to carry out the reaction. (4) After the reaction is complete, the solution is transferred to a heart-shaped flask and distilled under reduced pressure at 35 °C for 15 min to remove organic reagents. The remaining solution is washed repeatedly by centrifugation at 18500 g with anhydrous methanol until the supernatant is free of fluorescence. The precipitate is taken and resuspended in 0.1 wt% sodium dodecyl sulfate aqueous solution to obtain polymer fluorescent micro-nanoplastics.
[0039] Comparative Example 5 A method for preparing polymer fluorescent micro / nanoplastics includes the following steps: (1) Weigh 5 mg of polystyrene microspheres and disperse them in 2.5 mL of 0.25 wt% sodium dodecyl sulfonate aqueous solution. Dissolve them completely by sonication for 5 min with an ultrasonic power of 110 W to obtain a polystyrene microsphere dispersion. (2) Add 0.5 mL of acetonitrile to the mixed solution in step (2) and continue to mix by sonication to obtain a mixed solution; (3) Add 1.25 mL of anhydrous methanol to the polystyrene microsphere dispersion obtained in step (1), and then add 0.6 mg (1.5 mmol / L) Nile red fluorescent dye, sonicate for 10 min at an ultrasonic power of 110 W, and then stir at 25 °C for 2 h at a rate of 300 rpm to carry out the reaction. (4) After the reaction is complete, the solution is transferred to a heart-shaped flask and distilled under reduced pressure at 35 °C for 15 min to remove organic reagents. The remaining solution is washed repeatedly by centrifugation at 18500 g with anhydrous methanol until the supernatant is free of fluorescence. The precipitate is taken and resuspended in 0.1 wt% sodium dodecyl sulfate aqueous solution to obtain polymer fluorescent micro-nanoplastics.
[0040] Results Analysis 1. The fluorescence intensity of the fluorescent micro / nanoplastics prepared in Examples 1 and 2 was measured, and the results are shown in Table 1: Table 1. Fluorescence intensity of fluorescent micro / nanoplastics microspheres
[0041] 2. The fluorescence intensity of the fluorescent micro / nanoplastics prepared in Examples 1 and 3 was measured, and the results are shown in Table 2: Table 2. Fluorescence intensity of fluorescent micro / nanoplastics microspheres
[0042] 3. The fluorescence intensity of the fluorescent micro / nanoplastics prepared in Examples 1 and 4 was measured, and the results are shown in Table 3: Table 3. Fluorescence intensity of fluorescent micro / nanoplastics microspheres
[0043] 4. The fluorescence intensity of the fluorescent micro / nanoplastics prepared in Examples 1 and 5 was measured, and the results are shown in Table 4: Table 4. Fluorescence intensity of fluorescent micro / nanoplastics microspheres
[0044] 5. The fluorescent micro / nanoplastics microspheres prepared in Example 1 were scanned by electron microscopy, and the results are as follows: Figure 2 As shown in the figure, the prepared fluorescent micro-nanoplastics have good monodispersity and uniform size.
[0045] 6. The fluorescence intensity of the fluorescent micro / nanoplastics microspheres prepared in Example 1 and Comparative Examples 1-5 was measured, and the results are as follows: Figure 3 As shown: As shown in the figure, when the amount of tetrahydrofuran added is 0.5 mL and the amount of anhydrous methanol added is 1.25 mL, the nanoscale polystyrene fluorescent micro-nanoplastics prepared by the tetrahydrofuran / methanol composite swelling agent have high fluorescence intensity.
[0046] 7. The particle size and zeta potential of the fluorescent micro / nanoplastics microspheres prepared in Example 1 were measured, and the results are as follows: Figure 4 As shown, the particle size and zeta potential of the prepared fluorescent micro / nanoplastics microspheres are almost unchanged, consistent with those of untreated polystyrene microspheres, and exhibit high colloidal stability.
[0047] 8. The stability of the fluorescent micro / nanoplastics microspheres prepared in Example 1 was determined, and the results are as follows: Figure 5 As shown, the fluorescence intensity of polystyrene fluorescent microspheres remained unchanged after 40 days in 0.1% SDS aqueous solution, indicating good fluorescence stability.
[0048] 9. Fluorescence spectroscopy was performed on the fluorescent micro / nanoplastics microspheres prepared in Example 1, and the results are as follows: Figure 6 As shown, the obtained polystyrene fluorescent microspheres successfully found the main emission peak at 585 nm.
[0049] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.
Claims
1. A method for preparing fluorescent micro / nanoplastics microspheres, characterized in that, The method includes the following steps: (1) Disperse the polymer microspheres in an aqueous solution of sodium dodecyl sulfonate and mix them by ultrasonication to obtain a polymer microsphere dispersion; (2) Add tetrahydrofuran to the polymer microsphere dispersion obtained in step (1), and mix by ultrasonication to obtain a mixture; (3) Add anhydrous methanol to the mixture obtained in step (2), then add fluorescent dye, stir to react, distill under reduced pressure after reaction, and wash to obtain the final product.
2. The method according to claim 1, characterized in that, The polymer microspheres in step (1) include one or more of polystyrene microspheres, polymethyl methacrylate microspheres, and UV-aged polystyrene microspheres.
3. The method according to claim 1, characterized in that, The mass fraction of sodium dodecyl sulfonate in the sodium dodecyl sulfonate aqueous solution in step (1) is 0.25~0.5 wt%.
4. The method according to claim 1, characterized in that, In step (1), the ratio of the polymer microspheres to the sodium dodecyl sulfonate aqueous solution is 2~5:1~3, mg:mL.
5. The method according to claim 1, characterized in that, The ultrasound conditions in step (1) are: power of 100~200W and time of 5~10 min.
6. The method according to claim 1, characterized in that, The ratio of tetrahydrofuran to polymer microspheres in step (2) is 0.1~2.5:5; mL:mg.
7. The method according to claim 1, characterized in that, The volume ratio of anhydrous methanol to tetrahydrofuran is 1.25:0.1~2.
5.
8. The method according to claim 1, characterized in that, The ratio of anhydrous methanol to polymer microspheres in step (3) is 1~5:5, mL:mg.
9. The method according to claim 1, characterized in that, The fluorescent dye in step (2) includes any one of Nile Red, Rhodamine B, and tetraphenylethylene (TPE).
10. The method according to claim 1, characterized in that, The concentration of the fluorescent dye in step (2) is 0.5~3 mmol / L.
11. The method according to claim 1, characterized in that, The mass ratio of the polymer microspheres to the fluorescent dye is 5:0.2~1.
2.
12. The method according to claim 1, characterized in that, Before the stirring reaction in step (3), the mixture needs to be ultrasonically mixed evenly. The ultrasonic conditions are: power of 100~200 W and time of 5~10 min.
13. The method according to claim 1, characterized in that, The temperature of the stirring reaction in step (3) is 0~45℃.
14. The method according to claim 1, characterized in that, The stirring reaction time in step (3) is 0.5 to 4 hours.
15. The method according to claim 1, characterized in that, The vacuum distillation in step (3) is carried out at a temperature of 30-40°C for 10-15 minutes.
16. The method according to claim 1, characterized in that, The washing in step (3) specifically involves washing with anhydrous methanol until the supernatant shows no fluorescence at Ex / Em=552 nm / 585 nm.
17. The method according to claim 1, characterized in that, The volume ratio of anhydrous methanol to tetrahydrofuran is 1.25:0.5~1.
5.
18. Fluorescent micro / nanoplastics microspheres prepared by the method according to any one of claims 1 to 17.
19. The application of the fluorescent micro / nanoplastics microspheres according to claim 18 in imaging tracing and toxicology studies.
20. A method for improving the fluorescence intensity and stability of fluorescent micro / nanoplastics microspheres, characterized in that, The method includes the following steps: (1) Disperse the polymer microspheres in an aqueous solution of sodium dodecyl sulfonate and mix them by ultrasonication to obtain a polymer microsphere dispersion; (2) Add tetrahydrofuran to the polymer microsphere dispersion obtained in step (1), and mix by ultrasonication to obtain a mixture; (3) Add anhydrous methanol to the mixture obtained in step (2), then add fluorescent dye, mix with ultrasound, stir and react, distill under reduced pressure to remove organic reagents, wash, and obtain the final product.