Preparation method of lanthanide metal labeled amino modified fluorescent nano plastic microspheres

Abstract

The invention discloses a preparation method of lanthanide series metal labeled amino modified fluorescent nano plastic microspheres, which comprises the following steps: firstly, respectively dissolving and mixing 0.5-0.8 g of europium chloride hexahydrate and 1-1.5 g of 2-thiophenoyl trifluoroacetone, and precipitating and filtering to obtain a lanthanide series metal chelate; then adding 0.2-0.5 g of polyvinylpyrrolidone and the like into the three-necked flask, adjusting the pH value, raising the temperature, introducing nitrogen and removing oxygen; mixing and dispersing the chelate, a styrene monomer and a cross-linking agent to prepare an initiator solution; and finally adding the mixed solution into a flask, pouring an initiator, carrying out high-speed stirring reaction at 60-80 DEG C for 8-12 hours, and carrying out suction filtration and dialysis to obtain the microspheres. The method comprises the following steps: synthesizing a fluorescence-enhanced lanthanide metal chelate, combining with polyvinylpyrrolidone to form a core-shell structure fluorescent core, and coating with polystyrene to form a shell. The obtained microspheres are uniform in particle size, polystyrene shells have plastic pollutant characteristics and can be used for micro-nano plastic influence experiments, and coating of polyvinylpyrrolidone can prevent lanthanide metal chelate from being quenched by free radicals and avoid the influence of pH change.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polymers, in particular to a method for preparing lanthanide metal-labeled amino-modified fluorescent nano plastic microspheres. Background Art

[0002] Plastic pollution has become a global environmental problem. The sheer amount of plastic in water and soil has affected environmental health. People are gradually paying attention to the study of plastic pollution, especially micro-nano plastics with smaller particle sizes and greater hazards in the environment. Micro-nano plastics refer to microplastics with a size of 100nm-5mm and nanoplastics with a size of less than 100nm. As an emerging pollutant, they have complex structures, a wide variety, and are widely distributed. Currently, there is still a lack of in-depth research on micro-nano plastics, especially nanoplastics. Although studies have shown that micro-nano plastics can change soil structure, affect plant growth and development, and that small-particle micro-nano plastics can be absorbed by plants, leading to plant metabolic disorders, some studies have used fluorescently labeled micro-nano plastics to discuss the migration and fate of plastic particles in the environment. However, due to the shortcomings of the detection methods of micro-nano plastics, the problem of quantifying micro-nano plastics in complex environments remains difficult to solve.

[0003] Based on this current situation, we have prepared lanthanide metal-labeled fluorescent nanoplastic particles coated with styrene, which can help study the potential mechanisms, processes, and principles of the migration process of modified nanoplastics. Using lanthanide metal-labeled plastic microspheres has several advantages. First, the nanoplastic microspheres can be excited at 365nm and have strong red fluorescence, which can be used to track the migration of plants or pollutants in the environment. Second, the lanthanide metal content in the nanoplastic microspheres is stable, and the outer plastic component can be digested with strong acid to remove the outer plastic component, allowing the lanthanide metal content in the nanoplastic to be measured by ICP-MS.

[0004] Furthermore, the nanoplastic particles of the present invention have a uniform particle size and can be added directly to various environmental samples without worrying about interference from high metal or organic backgrounds. Therefore, those skilled in the art have provided a method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres to address the problems raised in the above-mentioned background technology. Summary of the Invention

[0005] The present invention addresses the problem of difficulty in quantifying nanoplastics in the environment and provides a method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres to solve the problems raised in the above background technology.

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

[0007] A method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres comprises the following steps:

[0008] S1: Dissolve 0.5-0.8 g of europium chloride hexahydrate in water, dissolve 1-1.5 g of 2-thenoyltrifluoroacetone in 30 ml of alcohol, pour the alcohol solution containing 2-thenoyltrifluoroacetone into the europium chloride solution, slowly add 1-2 mol / L sodium hydroxide solution dropwise to the solution under magnetic stirring until the precipitate no longer increases, heat to 50-60° C., react for 1-2 hours, and filter through a 0.45-1 μm filter membrane to obtain a white lanthanide metal chelate; S2: 0.2-0.5 g of polyvinyl pyrrolidone was added to a three-necked flask, 0.2-0.3 g of hexadecyltrimethylammonium chloride (CTAC) surfactant was added, and water or a mixed solution of water and anhydrous ethanol was added as a dispersion medium. 5-10 ml of Tris-HCl buffer solution was added to the three-necked flask to control the pH of the reaction system. The electric heating mantle was heated to 60-80° C. and nitrogen was passed through the reactor for 20-30 minutes to remove oxygen. S3: Add 0.08-0.2g of lanthanide metal chelate to a 10-20ml centrifuge tube, then add styrene monomer accounting for 10% of the total weight of the dispersion medium and styrene monomer, and continue to add 0.5-1.5% of the total weight of the styrene monomer, wherein the cross-linking agent is one or more of divinylbenzene or acrylonitrile, and ultrasonicate for 10-20min to uniformly disperse it. Take another 10-20ml centrifuge tube, add 3%-30% of the weight of the styrene monomer as water-soluble initiator AIBA and dissolve it in 5-10ml water; S4: Add a solution of lanthanide metal chelate to a three-necked flask, stir for 30-60 seconds, quickly pour in the initiator, and then carry out polymerization under high-speed stirring conditions, react at 60-80°C for 8-12 hours, take out the synthesized suspension, filter it under reduced pressure using a large-pore filter paper, and dialyze it through a dialysis bag to remove unreacted impurities, wherein the molecular weight that the dialysis bag can pass through is greater than the molecular weight of the added polyvinyl pyrrolidone.

[0009] As a further solution of the present invention: the amount of europium chloride hexahydrate in step S1 is 0.72 g.

[0010] As a further solution of the present invention: in step S1, the amount of 2-thenoyltrifluoroacetone is 1.33 g.

[0011] As a further solution of the present invention: the surfactant in step S2 is cetyltrimethylammonium chloride (CTAC).

[0012] As a further solution of the present invention: the dispersion medium in step S2 is water or a mixed solution of water and anhydrous ethanol.

[0013] As a further solution of the present invention: the cross-linking agent in step S3 is one or more of divinylbenzene or acrylonitrile, and the cross-linking agent accounts for 0.5-1.5% of the total weight of the styrene monomer.

[0014] In a further embodiment of the present invention, the initiator in step S3 is the water-soluble initiator AIBA. In a further embodiment of the present invention, the filtration in step S4 is performed using filter paper with a large pore size. In a further embodiment of the present invention, the molecular weight permeability of the dialysis bag selected in step S4 is greater than the molecular weight of the added polyvinylpyrrolidone. In a further embodiment of the present invention, the polymerization reaction is carried out under high-speed stirring at a speed of 400-900 rpm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention first synthesizes a fluorescence-enhanced lanthanide metal chelate, which is then combined with polyvinyl pyrrolidone to form a polyvinyl pyrrolidone-coated core-shell fluorescent core. Polystyrene is then added to form a polystyrene shell, resulting in spherical plastic microspheres with uniform particle size. The coated polystyrene exhibits the characteristics of a plastic pollutant and can be used in micro-nanoplastic impact experiments. Furthermore, encapsulating the lanthanide metal chelate in polyvinyl pyrrolidone prevents quenching of the lanthanide metal chelate by free radicals generated by the initiator during the synthesis process, as well as preventing the lanthanide metal chelate from being affected by changes in solution pH.

[0017] 2. The surface of the lanthanide metal-labeled amino-modified plastic microspheres prepared by the present invention is positively charged and can simulate positively charged micro-nanoplastics in the environment.

[0018] 3. The lanthanide metal-labeled plastic microspheres prepared by the present invention can be used for quantitative analysis in complex environments.

[0019] 4. The lanthanide metals in the lanthanide metal-labeled plastic microspheres prepared by the present invention are stably bound and hardly leak out of the plastic microspheres, and can be used to analyze the behavior of positively charged nanoplastics in a laboratory simulating a natural environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The zeta potential of the prepared nano-lanthanide metal labeled amino-modified plastic microspheres;

[0021] Figure 2 Transmission electron micrograph of the lanthanide metal-labeled plastic microspheres prepared in Example 2 and a distribution diagram of the element contents therein; Figure 3 The infrared spectrum of the prepared nano-lanthanide metal labeled amino-modified plastic microspheres;

[0022] Figure 4This is the excitation and emission spectra of the plastic microspheres in the invention. DETAILED DESCRIPTION

[0023] See also Figures 1 to 4 In an embodiment of the present invention, a method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres is provided.

[0024] Example 1:

[0025] The preparation method of this embodiment comprises the following steps: first, preparing a lanthanide metal chelate: placing 0.72 g of europium chloride hexahydrate in a beaker, adding an appropriate amount of deionized water, and stirring until completely dissolved; taking another 1.33 g of 2-thenoyltrifluoroacetone and adding it to 30 ml of anhydrous ethanol, ultrasonically oscillating it to fully dissolve it. Subsequently, the ethanol solution containing 2-thenoyltrifluoroacetone is slowly poured into the europium chloride aqueous solution and stirred and mixed on a magnetic stirrer at a speed of 300 r / min. While stirring, 2 mol / L sodium hydroxide solution is slowly added dropwise until the precipitate produced in the solution no longer increases, the reaction system is heated to 60°C, and the reaction is stirred continuously for 1 hour. After the reaction is completed, the filter is filtered using a 0.45 micron filter membrane, and the filter cake is washed with deionized water several times, and dried to obtain a white lanthanide metal chelate.

[0026] Next, prepare the reaction system: Add 0.2g of polyvinylpyrrolidone, 0.2g of hexadecyltrimethylammonium chloride (CTAC) surfactant, and 50ml of deionized water as the dispersion medium to a 250ml three-necked flask. Install a stirring device and reflux condenser. Stir the mixture at 400 rpm using a magnetic stirrer to thoroughly mix the components. Then, add 5ml of Tris-HCl buffer (pH 8.0) to the three-necked flask to adjust the pH of the reaction system. Place the three-necked flask in a heating mantle and heat to 70°C. Simultaneously, introduce nitrogen for 30 minutes to expel oxygen from the reactor.

[0027] Next, prepare the reaction solution: Add 0.2g of the lanthanide metal chelate prepared above to a 10ml centrifuge tube, followed by 5ml of styrene monomer (styrene monomer accounts for 10% of the total weight of the dispersion medium and styrene monomer), followed by 500μl of divinylbenzene and 500μl of acrylonitrile as a crosslinker (crosslinker accounts for 1% of the total weight of the styrene monomer). Ultrasonicate for 10 minutes to evenly disperse the components. In a separate 10ml centrifuge tube, add 0.3g of the water-soluble initiator AIBA (initiator accounts for 6% of the total weight of the styrene monomer), 5ml of deionized water, and stir to completely dissolve.

[0028] Finally, the polymerization reaction was carried out: the lanthanide metal chelate solution was quickly poured into a nitrogen-filled three-necked flask. After stirring for 30 seconds, the initiator solution was quickly added, and the stirring speed was immediately increased to 600 rpm. The reaction was continued at 70°C for 12 hours. After the reaction was completed, heating and stirring were stopped, and the resulting suspension was removed and filtered under reduced pressure using a large-pore filter paper to collect the filter cake. The filter cake was placed in a 47,000 Da dialysis bag and dialyzed against deionized water for one week to remove unreacted monomer, initiator, and other impurities. The resulting metal-labeled amino-modified nanoplastic microspheres had an average particle size of approximately 80 nm.

[0029] Example 2:

[0030] The preparation method of this embodiment comprises the following specific steps:

[0031] The method comprises the following steps: first, preparing a lanthanide metal chelate: placing 0.72 g of europium chloride hexahydrate in a beaker, adding an appropriate amount of deionized water, and stirring until completely dissolved; taking another 1.33 g of 2-thenoyltrifluoroacetone, adding it to 30 ml of anhydrous ethanol, and ultrasonically oscillating it to fully dissolve it. Subsequently, the ethanol solution containing the 2-thenoyltrifluoroacetone is slowly poured into the europium chloride aqueous solution, and the mixture is stirred and mixed on a magnetic stirrer at a speed of 300 r / min. While stirring, a 2 mol / L sodium hydroxide solution is slowly added dropwise until the precipitate in the solution no longer increases. The reaction system is heated to 60°C and stirred for 1 hour. After the reaction is completed, the reaction is filtered using a 0.45 micron filter membrane, and the filter cake is washed with deionized water multiple times. After drying, a white lanthanide metal chelate is obtained.

[0032] Next, prepare the reaction system: Add 0.5g of polyvinylpyrrolidone, 0.2g of hexadecyltrimethylammonium chloride (CTAC) surfactant, and 50ml of deionized water as the dispersion medium to a 250ml three-necked flask. Install a stirring device and reflux condenser. Stir the mixture at 400 rpm using a magnetic stirrer to thoroughly mix the components. Then, add 5ml of Tris-HCl buffer (pH 8.0) to the three-necked flask to adjust the pH of the reaction system. Place the three-necked flask in a heating mantle and heat to 75°C. Simultaneously, introduce nitrogen for 30 minutes to expel oxygen from the reactor.

[0033] Next, prepare the reaction solution: Add 0.2g of the lanthanide metal chelate prepared above to a 10ml centrifuge tube, followed by 5ml of styrene monomer (styrene monomer accounts for 10% of the total weight of the dispersion medium and styrene monomer), followed by 500μl of divinylbenzene and 500μl of acrylonitrile as a crosslinker (crosslinker accounts for 1% of the total weight of the styrene monomer). Ultrasonicate for 10 minutes to evenly disperse the components. In a separate 10ml centrifuge tube, add 0.3g of the water-soluble initiator AIBA (initiator accounts for 6% of the total weight of the styrene monomer), 5ml of deionized water, and stir to completely dissolve.

[0034] Finally, the polymerization reaction was carried out: the lanthanide metal chelate solution was quickly poured into a nitrogen-filled three-necked flask. After stirring for 30 seconds, the initiator solution was quickly added, and the stirring speed was immediately increased to 600 rpm. The reaction was continued at 70°C for 12 hours. After the reaction was completed, heating and stirring were stopped, and the resulting suspension was removed and filtered under reduced pressure using a large-pore filter paper to collect the filter cake. The filter cake was placed in a 47,000 Da dialysis bag and dialyzed against deionized water for one week to remove unreacted monomer, initiator, and other impurities. The resulting metal-labeled amino-modified nanoplastic microspheres had an average particle size of approximately 60 nm.

[0035] The present invention first synthesizes a fluorescence-enhanced lanthanide metal chelate, which is then combined with polyvinyl pyrrolidone to form a fluorescent core with a polyvinyl pyrrolidone-coated core-shell structure. Polystyrene is then added for coating to form a polystyrene shell, thereby producing spherical plastic microspheres with uniform particle size. The coated polystyrene has the characteristics of a plastic pollutant and can be used in experiments on the impact of micro-nanoplastics. Moreover, coating the lanthanide metal chelate in polyvinyl pyrrolidone avoids quenching of the lanthanide metal chelate by free radicals generated by the initiator during the synthesis process, as well as avoiding the lanthanide metal chelate being affected by changes in solution pH. The lanthanide metal-labeled amino-modified plastic microspheres prepared by the present invention have a positively charged surface and can simulate positively charged micro-nanoplastics in the environment. They can also be used for quantitative analysis in complex environments. The lanthanide metal in the lanthanide metal-labeled plastic microspheres prepared by the present invention is stably bound and almost does not leak from the plastic microspheres. They can be used in laboratory analysis to simulate the behavior of positively charged nanoplastics in natural environments.

[0036] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres, characterized in that: The steps include: S1: Dissolve 0.5-0.8 g of europium chloride hexahydrate in water, dissolve 1-1.5 g of 2-thenoyltrifluoroacetone in 30 ml of alcohol, pour the alcohol solution containing 2-thenoyltrifluoroacetone into the europium chloride solution, slowly add 1-2 mol / L sodium hydroxide solution dropwise to the solution under magnetic stirring until the precipitate no longer increases, heat to 50-60° C., react for 1-2 hours, and filter through a 0.45-1 μm filter membrane to obtain a white lanthanide metal chelate; S2: 0.2-0.5 g of polyvinyl pyrrolidone was added to a three-necked flask, 0.2-0.3 g of hexadecyltrimethylammonium chloride (CTAC) surfactant was added, and water or a mixed solution of water and anhydrous ethanol was added as a dispersion medium. 5-10 ml of Tris-HCl buffer solution was added to the three-necked flask to control the pH of the reaction system. The electric heating mantle was heated to 60-80° C. and nitrogen was passed through the reactor for 20-30 minutes to remove oxygen. S3: Add 0.08-0.2g of lanthanide metal chelate to a 10-20ml centrifuge tube, then add styrene monomer accounting for 10% of the total weight of the dispersion medium and styrene monomer, and continue to add 0.5-1.5% of the total weight of the styrene monomer, wherein the cross-linking agent is one or more of divinylbenzene or acrylonitrile, and ultrasonicate for 10-20min to uniformly disperse it. Take another 10-20ml centrifuge tube, add 3%-30% of the weight of the styrene monomer as water-soluble initiator AIBA and dissolve it in 5-10ml water; S4: Add a solution of lanthanide metal chelate to a three-necked flask, stir for 30-60 seconds, quickly pour in the initiator, and then carry out polymerization under high-speed stirring conditions, react at 60-80°C for 8-12 hours, take out the synthesized suspension, filter it under reduced pressure using a large-pore filter paper, and dialyze it through a dialysis bag to remove unreacted impurities, wherein the molecular weight that the dialysis bag can pass through is greater than the molecular weight of the added polyvinyl pyrrolidone.

2. The method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: The amount of europium chloride hexahydrate in step S1 is 0.72 g.

3. The method for preparing a lanthanide metal labeled amino-modified fluorescent nanoplastic microsphere according to claim 1, characterized in that: The amount of 2-thenoyltrifluoroacetone in step S1 is 1.33 g.

4. The method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: The surfactant in step S2 is cetyltrimethylammonium chloride (CTAC).

5. The method for preparing lanthanide metal labeled amino-modified fluorescent nano plastic microspheres according to claim 1, characterized in that: The dispersion medium in step S2 is water or a mixed solution of water and anhydrous ethanol.

6. The method for preparing lanthanide metal labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: The cross-linking agent in step S3 is one or more of divinylbenzene or acrylonitrile, and the cross-linking agent accounts for 0.5-1.5% of the total weight of the styrene monomer.

7. The method for preparing lanthanide metal labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: The initiator in step S3 is water-soluble initiator AIBA.

8. The method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: In step S4, filter paper with large pore size is used for filtration.

9. The method for preparing lanthanide metal-labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: The molecular weight of the dialysis bag selected in step S4 is greater than the molecular weight of the added polyvinyl pyrrolidone.

10. The method for preparing lanthanide metal labeled amino-modified fluorescent nanoplastic microspheres according to claim 1, characterized in that: The polymerization reaction is carried out under high-speed stirring conditions at a rotation speed of 400-900 r / min.

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