CN116004220A - Method for preparing quantum dot microspheres by precipitation polymerization method, quantum dot microspheres and applications - Google Patents

Abstract

The invention discloses a method for preparing quantum dot microspheres by a precipitation polymerization method, quantum dot microspheres and applications, and relates to the technical field of quantum dots. First control the concentration of quantum dots and monomers in the system, so that the ligands on the quantum dots are aggregated, and the quantum dots are agglomerated to form quantum dot clusters. The quantum dot clusters can continue to be stably dispersed by the quantum dot ligands on the surface of the clusters. in solvent. After the quantum dot nucleation period is over, monomer polymerization is carried out, and its concentration is kept below the critical nucleation concentration. The oligomers generated by polymerization gradually adsorb and grow on the quantum dot clusters to form quantum dot microspheres. By separating the nucleation and growth processes, quantum dot microspheres with uniform quantum dot distribution and uniform loading can be directly synthesized when preparing quantum dot microspheres.

Description

Method for preparing quantum dot microspheres by precipitation polymerization method, quantum dot microspheres and applications

technical field

The invention relates to the technical field of quantum dots, in particular to a method for preparing quantum dot microspheres by precipitation polymerization, quantum dot microspheres and applications.

Background technique

Quantum dots have the advantages of adjustable fluorescence emission wavelength, high photoluminescence quantum yield (PLQY), and good fluorescence stability, and are favored in the quantitative detection of proteins, nucleic acids, cells and other biomarkers. However, quantum dots have small particle size and high surface energy, and are easy to agglomerate when used alone, resulting in abnormal test results and limiting their application scenarios.

Load multiple quantum dots in a microsphere to form quantum dot fluorescent microspheres, which can provide a protective shell for quantum dots and provide charged coupling groups. The mutual repulsion of the surface potential can effectively avoid the aggregation of microspheres . Copolymerization of quantum dots and monomers is a common method for preparing quantum dot fluorescent microspheres with uniform particle size, but it often requires complicated separation and purification to obtain microspheres with uniform distribution of quantum dots, and it is difficult to synthesize quantum dots with uniform distribution and load in one step Uniform quantum dot microspheres.

Quantum dots are embedded in the process of preparing microspheres with uniform particle size through copolymerization with monomers, such as suspension polymerization, emulsion polymerization, etc. These methods can ensure that quantum dots do not leak in the use environment, but the continuous The phases are all water, and the high PLQY oil phase quantum dots cannot exist in monodisperse in it, and it is difficult to ensure the uniformity of fluorescence of quantum dot microspheres, which affects the application in accurate quantitative detection.

Precipitation polymerization method is a synthesis method that dissolves all materials in a good solvent and precisely controls the synthesis of monodisperse microspheres. However, if quantum dots are directly dispersed in a good solvent to form a quasi-homogeneous system, quantum dots will affect the nucleation of monomers and form a large number of aggregates, and it is still difficult to ensure the uniformity of fluorescence of quantum dot microspheres.

Therefore, how to realize the uniformity of fluorescence of quantum dot microspheres is an urgent problem to be solved when preparing quantum dot microspheres.

In view of this, the present invention is proposed.

Contents of the invention

The purpose of the present invention is to provide a method for preparing quantum dot microspheres by precipitation polymerization, quantum dot microspheres and applications, aiming at significantly improving the uniformity of quantum dot microspheres and making the distribution and loading of quantum dots more uniform.

The present invention is achieved like this:

In the first aspect, the present invention provides a method for preparing quantum dot microspheres by precipitation polymerization, comprising:

Mixing quantum dots, initiators and monomers in a good solvent to obtain a nucleation reaction solution, and performing a quantum dot nucleation reaction on the nucleation reaction solution; wherein, the volume fraction of monomers in the nucleation reaction solution is less than 0.4%;

After the quantum dot nucleation reaction, add a mixed solution formed by monomers, initiators and crosslinking agents to the system for polymerization reaction, by controlling the addition rate of the mixed solution, the concentration of monomers in the process is controlled at the critical nucleation concentration the following.

In an optional embodiment, the quantum dots are first mixed with a good solvent, the temperature is raised to 80°C-95°C, and the quantum dot dispersion is obtained after purging nitrogen to remove oxygen;

Mix and dissolve the initiator, monomer and good solvent to obtain a monomer solution, mix the quantum dot dispersion and the monomer solution to obtain a nucleation reaction solution, and react at 80°C-95°C for 1h-4h;

Preferably, the monomer solution is injected into the quantum dot dispersion.

In an optional embodiment, the quantum dots are quantum dots containing vinyl ligands on the surface, and the mass of quantum dots per 100 milliliters of quantum dot dispersions is 0.3g-1g, the volume ratio of quantum dot dispersions and monomer solutions 200:1.0-2.0;

Preferably, the vinyl ligands on the surface of the quantum dots are selected from at least one of alkenoic acids and their derivatives, acrylates and their derivatives, and methacrylates and their derivatives;

More preferably, the vinyl ligands on the surface of the quantum dots are selected from the group consisting of n-octenoic acid, n-nonenoic acid, n-decenoic acid, phosphate acrylate, ethylene glycol acrylate, propylene glycol methacrylate and methacrylic acid at least one of butanediol esters.

In an optional embodiment, the good solvent is selected from non-coordinating inert solvents with a solubility parameter of 21-25;

Preferably, the good solvent is at least one selected from tetrachloroethane, pyridine, cyclohexanol, n-butanol, isobutanol, n-propanol, acetonitrile and dimethylformamide.

In an optional embodiment, the monomer in the monomer solution is a compound or a derivative thereof that contains only one vinyl group;

Preferably, the monomer is selected from at least one of styrene, chlorostyrene, methyl methacrylate, ethyl methacrylate, propyl acrylate, butyl acrylate and acrylic acid;

Preferably, when preparing the monomer solution, the volume ratio of the monomer and the good solvent is controlled to be 1:1-10;

Preferably, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanonitrile and azoisobutyrocyanoformamide; the content of the corresponding initiator per 100mL milliliter nucleation reaction solution is 0.001g- 0.01g.

In an optional embodiment, after the quantum dot nucleation reaction, the volume ratio of the volume of the reaction solution in the reactor to the mixed solution is 30-50:1, and after the mixed solution is added dropwise to the reaction solution, at 60°C-80°C Continue to react for 2h-5h under the condition;

Preferably, the dropping time of the mixed solution is controlled to be 40min-70min;

More preferably, the drop rate of the mixed solution is 0.05mL/min-0.15mL/min.

In an optional embodiment, during the preparation of the mixed solution, the volume ratio of the monomer and the crosslinking agent is 2.3-19:1, and the total volume of the monomer and the crosslinking agent is V, and V of 100mL corresponds to the initiator The content is 0.1g-1g.

In an optional embodiment, the crosslinking agent is selected from compounds containing at least two vinyl groups;

Preferably, the crosslinking agent is selected from divinylbenzene, allyl ether, diethyl diallyl malonate, diallyl disulfide, ethylene glycol diacrylate, ethylene glycol dimethacrylate , 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butane At least one of diol diacrylate and 1,4-butanediol dimethacrylate.

In a second aspect, the present invention provides a quantum dot microsphere prepared by the preparation method in any one of the foregoing embodiments.

In a third aspect, the present invention provides the application of the quantum dot microspheres of the aforementioned embodiments in quantitative detection.

The present invention has the following beneficial effects: first control the concentration of quantum dots and monomers in the system, so that the ligands on the quantum dots are aggregated, the quantum dots are agglomerated, and quantum dot clusters are formed, and the quantum dot clusters can continue to be formed by the quantum Dot ligands are stably dispersed in good solvents. After the quantum dot nucleation period is over, monomer polymerization is carried out, and its concentration is kept below the critical nucleation concentration. The oligomers generated by polymerization gradually adsorb and grow on the quantum dot clusters to form quantum dot microspheres. By separating the nucleation and growth processes, quantum dot microspheres with uniform quantum dot distribution and uniform loading can be directly synthesized when preparing quantum dot microspheres.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is the electron micrograph of the quantum fluorescence microsphere that embodiment 1 prepares;

Fig. 2 is the electron micrograph of the quantum fluorescent microsphere that embodiment 2 prepares;

Fig. 3 is the fluorescence emission figure of embodiment 1, comparative example 2;

FIG. 4 is the fluorescence emission diagrams of Example 1 and Comparative Example 3.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

The embodiment of the present invention provides a method for preparing quantum dot microspheres by precipitation polymerization, comprising the following steps:

S1, quantum dot nucleation

Mixing quantum dots, initiators and monomers in a good solvent to obtain a nucleation reaction solution, and performing a quantum dot nucleation reaction on the nucleation reaction solution; wherein, the volume fraction of monomers in the nucleation reaction solution is less than 0.4%, and the amount of monomers Strict control is performed to effectively avoid spontaneous nucleation of monomers.

In the actual operation process, first mix the quantum dots with a good solvent, raise the temperature to 80°C-95°C, pass through nitrogen and remove oxygen to obtain a quantum dot dispersion, and set aside; mix and dissolve the initiator, monomer and good solvent to obtain a monomer solution, Mixing the quantum dot dispersion liquid and the monomer solution to obtain a nucleation reaction liquid, and reacting for 1h-4h under the condition of 80°C-95°C, so as to fully react the ligand groups on the quantum dots.

Specifically, the reaction temperature can be 80°C, 83°C, 85°C, 87°C, 90°C, 92°C, 95°C, etc., and the reaction time can be 1h, 2h, 3h, 4h, etc., or the above adjacent values any value in between.

In some embodiments, the monomer solution can be injected into the quantum dot dispersion, and the monomer solution can be injected into the quantum dot dispersion at one time by means of a syringe.

In some embodiments, the vinyl ligands on the surface of the quantum dots are selected from at least one of alkenoic acids and their derivatives, acrylates and their derivatives, and methacrylates and their derivatives; preferably, the quantum dots The vinyl ligands on the surface are selected from n-octenoic acid, n-nonenoic acid, n-decenoic acid, phosphate acrylate, ethylene glycol acrylate, propylene glycol methacrylate and butylene glycol methacrylate. At least one, can be any one or more of the above.

In some embodiments, the good solvent is selected from non-coordinating inert solvents with a solubility parameter (calculated by the molar attraction constant and molecular weight of the structural group) of 21-25, such as tetrachloroethane, pyridine, cyclohexanol, n- Butanol, isobutanol, n-propanol, acetonitrile and dimethylformamide, etc., can be any one or more of the above. The calculation of the above solubility parameters is a conventional calculation method, which can be calculated according to the molar attraction constant of the structural group, the formula is as follows:

In the formula, ρ is the relative density, Fi is the molar attraction constant, and M0 is the molecular weight of the molecule. See "Polymer Physics" Chemical Industry Press, 4th edition, pages 82-86 for details.

In some embodiments, the monomer in the monomer solution is a compound or a derivative thereof that contains only one vinyl group; preferably, the monomer is selected from styrene, chlorostyrene, methyl methacrylate, methyl At least one of ethyl acrylate, propyl acrylate, butyl acrylate and acrylic acid may be any one or more of the above.

The type of initiator is not limited. In some embodiments, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanonitrile and azoisobutyrocyanoformamide, and can be any of the above species or several.

In order to better control the nucleation of quantum dots and make the obtained quantum dot clusters more uniform, the inventors have precisely controlled the amount of each raw material: the mass of quantum dots corresponding to 100 ml of quantum dot dispersion is 0.3g-1g, The volume ratio of the quantum dot dispersion liquid and the monomer solution is 200:1.0-2.0; the volume ratio of the monomer and the good solvent is controlled to be 1:1-10, and the content of the corresponding initiator per 100mL of the nucleation reaction solution is 0.01g-0.1g .

Specifically, the mass of quantum dots corresponding to every 100 ml of quantum dot dispersion liquid can be 0.3g, 0.5g, 0.7g, 1.0g, etc. The concentration of quantum dots should not be too large, otherwise it will lead to difficult control of the nucleation period and the formation of Visible reunion.

Specifically, the volume ratio of the quantum dot dispersion liquid to the monomer solution can be 200:1.0, 200:1.5, 200:2.0, etc., or any value between the above adjacent values.

Specifically, when preparing the monomer solution, the volume ratio of the monomer and the good solvent can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc., the concentration of the monomer should not be too large, so that the concentration after injection is less than 0.4% (v/v), to avoid spontaneous nucleation.

Specifically, the content of the initiator per 100 mL of milliliter nucleation reaction solution can be 0.01g, 0.03g, 0.05g, 0.07g, 0.10g, etc. The free radicals decomposed by the initiator have strong oxidative properties, and too much initiator will cause quantum Oxidation defects are formed on the surface of the dots, which affect the fluorescence performance, so the concentration of the initiator needs to be controlled at 0.01%-0.1% (m/V).

S2, monomer polymerization

After the nucleation reaction of quantum dots, add the mixed solution formed by monomer, initiator and crosslinking agent to the system for polymerization reaction, and control the total concentration of monomer and crosslinking agent in the process by controlling the adding rate of the mixed solution. below the critical nucleation concentration. The critical nucleation concentration can be controlled according to experience. If there is no relevant experience in actual operation, the dropping rate can be controlled to be slow enough, and it is enough to drop slowly.

In the actual operation process, after the quantum dot nucleation reaction, the volume ratio of the reaction liquid in the reaction kettle to the mixed solution is 30-50:1. After the mixed solution is added dropwise to the reaction liquid, the Continue to react for 2h-5h, the amount of mixed solution is small, control its slow addition to ensure that the total concentration of monomers and crosslinking agents is always below the critical nucleation concentration, to prevent secondary nucleation of monomers, and oligomers generated by polymerization Gradually adsorb and grow on the quantum dot clusters to form quantum dot microspheres. After the reaction is completed, the quantum dot fluorescent microspheres are obtained by centrifuging and replacing the solvent.

Specifically, after the quantum dot nucleation reaction, the volume ratio of the volume of the reaction solution in the reactor to the mixed solution can be 30:1, 35:1, 40:1, 45:1, 50:1, etc.; The time is 40min-70min to ensure that the total concentration of monomers and cross-linking agents is always below the critical nucleation concentration. Specifically, it can be 40min, 50min, 60min, 70min, etc. Specifically, the drop rate of the mixed solution may be 0.05mL/min-0.15mL/min, such as 0.05mL/min, 0.10mL/min, 0.15mL/min, etc.

In order to further control the polymerization reaction of the monomers and obtain uniform quantum dot microspheres, the inventors optimized the amount of each raw material: during the preparation of the mixed solution, the volume ratio of the monomers to the crosslinking agent was 2.3-19:1 , assuming that the total volume of the monomer and the crosslinking agent is V, the content of V corresponding to 100mL of the initiator is 0.1g-1g.

Specifically, the volume ratio of the monomer and the crosslinking agent can be 2.3:1, 2.5:1, 3.0:1, 5.0:1, 7.0:1, 9.0:1, 13.0:1, 15.0:1, 17.0:1, 19.0:1 etc. The content of V corresponding to 100 mL of initiator can be 0.1 g, 0.3 g, 0.5 g, 0.7 g, 1.0 g, etc. If the proportion of cross-linking agent is too high, the critical nucleation concentration will decrease, and the monomer/cross-linking agent will easily self-nucleate; Functional polymer shell, not dispersible in aqueous solution.

In some embodiments, the crosslinking agent is selected from compounds containing at least two vinyl groups; preferably, the crosslinking agent is selected from divinylbenzene, allyl ether, diethyl diallylmalonate, diene Propyl Disulfide, Ethylene Glycol Diacrylate, Ethylene Glycol Dimethacrylate, 1,3-Propanediol Diacrylate, 1,3-Propanediol Dimethacrylate, 1,3-Butanediol Diacrylate At least one of ester, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate and 1,4-butanediol dimethacrylate, can be any of the above or several.

It should be noted that, in the preparation method provided by the embodiment of the present invention, in the nucleation stage, the quantum dots containing vinyl ligands are dispersed in a good solvent, nucleated under the action of an initiator, and then the monomer/crosslinked A coupling agent-initiator mixed solution, the mixed solution can be dissolved in a good solvent, under quasi-homogeneous conditions, the quantum dot fluorescent microspheres are prepared by a precipitation polymerization method.

The embodiment of the present invention provides a quantum dot microsphere, which is prepared by the above preparation method. By separating the nucleation and growth steps in a quasi-homogeneous system, quantum dot fluorescence with uniform particle size and uniform quantum dot loading can be obtained. Microspheres can be applied in quantitative detection, which is beneficial to further improve detection accuracy.

The characteristics and performance of the present invention will be described in further detail below in conjunction with the examples.

Example 1

This embodiment provides a method for preparing quantum dot microspheres by precipitation polymerization, comprising the following steps:

(1) Disperse 2.0g of quantum dots (ZnCdSe quantum dots, the same below) in 200mL of tetrachloroethane, raise the temperature to 90°C in the reactor, keep stirring, pass nitrogen and remove oxygen for later use.

(2) Dissolve 0.02 g of azobisisobutyronitrile with 0.8 mL of styrene and 0.8 mL of tetrachloroethane, inject it into the reactor, and react at 90° C. for 3 h.

(3) Dissolve 0.05g of azobisisobutyronitrile with 3mL of styrene, 0.5mL of acrylic acid, and 1.5mL of divinylbenzene, and add it dropwise to the system obtained in step (2) at a rate of 0.1mL/min. After the addition was completed, the reaction was continued at 70°C for 3 hours, collected by centrifugation, and then dispersed with pure water, and repeated twice.

The electron micrograph of the quantum dot fluorescent microspheres prepared in Test Example 1 is shown in FIG. 1 . It can be seen that the prepared quantum dot fluorescent microspheres are evenly distributed, have uniform particle size, and uniform quantum dot loading.

Example 2

This embodiment provides a method for preparing quantum dot microspheres by precipitation polymerization, comprising the following steps:

(1) Disperse 2.0g of quantum dots in 200mL of pyridine, raise the temperature to 90°C in the reactor, keep stirring, pass nitrogen and remove oxygen for later use.

(2) Dissolve 0.002g of azobisisobutyronitrile in 0.1mL of styrene and 1.0mL of tetrachloroethane, inject it into the reactor, and react at 90°C for 3h.

(3) Dissolve 0.005g of azobisisobutyronitrile with 4.25mL of styrene, 0.5mL of acrylic acid, and 0.25mL of divinylbenzene, and add it dropwise to the system obtained in step (2) at a rate of 0.1mL/min. After the dropwise addition, the reaction was continued at 70° C. for 3 h, collected by centrifugation, and dispersed with pure water, and repeated twice.

The electron micrograph of the quantum dot fluorescent microspheres prepared in Test Example 1 is shown in FIG. 2 . It can be seen that the prepared quantum dot fluorescent microspheres are evenly distributed, have uniform particle size, and uniform quantum dot loading.

Comparative example 1

This comparative example provides a method for preparing quantum dot microspheres by precipitation polymerization, the only difference from Example 1 is that the solution in step (3) is directly added dropwise without reaction after being injected into the reactor in step (2) . details as follows:

(1) Disperse 2.0g of quantum dots in 200mL of tetrachloroethane, raise the temperature to 90°C in the reactor, keep stirring, pass nitrogen and remove oxygen for later use.

(2) Dissolve 0.02 g of azobisisobutyronitrile with 0.8 mL of styrene and 0.8 mL of tetrachloroethane, and inject it into the reactor.

(3) Dissolve 0.05g of azobisisobutyronitrile with 3mL of styrene, 0.5mL of acrylic acid, and 1.5mL of divinylbenzene, and add it dropwise to the mixed system in step (2) at a rate of 0.1mL/min. After the dropwise addition, the reaction was continued at 70° C. for 3 h, collected by centrifugation, and dispersed with pure water, and repeated twice.

Comparative example 2

This comparative example provides a method for preparing quantum dot microspheres by precipitation polymerization, the only difference from Example 1 is that the amount of quantum dots in step (1) is increased to 5 g.

Comparative example 3

This comparative example provides a method for preparing quantum dot microspheres by precipitation polymerization, the only difference from Example 1 is that the amount of initiator used in step (2) is increased to 0.2 g.

Test case

The fluorescence emission figure of embodiment 1, comparative example 2 is as shown in Figure 3, and solid line is embodiment 1, and the particle size of quantum dot cluster is uniform, has and has only one particle diameter peak; Dotted line is comparative example 2, and quantum dot amount exceeds Many, the quantum dots form uncontrollable agglomeration, the particle size is not uniform, and there are two broad particle size peaks.

The fluorescence emission diagrams of Example 1 and Comparative Example 3 are shown in Figure 4. The solid line is Example 1, and the dotted line is Comparative Example 3. Excessive initiators in the nucleation stage directly lead to the formation of oxidation defects on the surface of quantum dots, resulting in obvious fluorescence intensity. reduce.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method for preparing quantum dot microspheres by precipitation polymerization, is characterized in that, comprising: Mixing quantum dots, initiators and monomers in a good solvent to obtain a nucleation reaction solution, and performing a quantum dot nucleation reaction on the nucleation reaction solution; wherein, the volume fraction of the monomer in the nucleation reaction solution is less than 0.4%; After the quantum dot nucleation reaction, add the mixed solution formed by the monomer, initiator and crosslinking agent to the system to carry out the polymerization reaction, by controlling the addition rate of the mixed solution, to control the concentration of the monomer in the process. below the critical nucleation concentration. 2. The method according to claim 1, wherein the quantum dots are first mixed with the good solvent, the temperature is raised to 80°C-95°C, and the quantum dot dispersion is obtained after purging nitrogen to remove oxygen; The initiator, the monomer and the good solvent are mixed and dissolved to obtain a monomer solution, and the quantum dot dispersion and the monomer solution are mixed to obtain the nucleation reaction solution. Under the condition of reaction 1h-4h; Preferably, the monomer solution is injected into the quantum dot dispersion. 3. The method according to claim 2, wherein the quantum dots are quantum dots whose surface contains vinyl ligands, and the quality of the quantum dots corresponding to the quantum dot dispersion per 100 milliliters is 0.3g-1g, The volume ratio of the quantum dot dispersion and the monomer solution is 200:1.0-2.0; Preferably, the vinyl ligands on the surface of the quantum dots are selected from at least one of alkenoic acids and their derivatives, acrylates and their derivatives, and methacrylates and their derivatives; More preferably, the vinyl ligands on the surface of the quantum dots are selected from the group consisting of n-octenoic acid, n-nonenoic acid, n-decenoic acid, phosphate acrylate, ethylene glycol acrylate, propylene glycol methacrylate and methyl At least one of butylene glycol acrylate. 4. the method according to claim 3 is characterized in that, described good solvent is selected from the non-coordination inert solvent of solubility parameter at 21-25; Preferably, the good solvent is selected from at least one of tetrachloroethane, pyridine, cyclohexanol, n-butanol, isobutanol, n-propanol, acetonitrile and dimethylformamide. 5. The method according to claim 3, characterized in that, the monomer in the monomer solution is a compound or derivative thereof that contains only one vinyl group; Preferably, the monomer is selected from at least one of styrene, chlorostyrene, methyl methacrylate, ethyl methacrylate, propyl acrylate, butyl acrylate and acrylic acid; Preferably, when preparing the monomer solution, the volume ratio of the monomer and the good solvent is controlled to be 1:1-10; Preferably, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanonitrile and azoisobutyrocyanoformamide; every 100mL milliliter of the nucleation reaction solution corresponds to the initiator The content is 0.001g-0.01g. 6. method according to claim 2, it is characterized in that, the volume of reaction solution in the reactor after quantum dot nucleation reaction and the volume ratio of described mixed solution are 30-50: 1, described mixed solution is added dropwise to After the reaction solution, continue to react for 2h-5h under the condition of 60°C-80°C; Preferably, the dropping time of controlling the mixed solution is 40min-70min; More preferably, the dropping rate of the mixed solution is 0.05mL/min-0.15mL/min. 7. method according to claim 6, is characterized in that, in the preparation process of described mixed solution, the volume ratio of described monomer and described linking agent is 2.3-19: 1, suppose described monomer and The total volume of the crosslinking agent is V, and 100 mL of V corresponds to a content of 0.1 g-1 g of the initiator. 8. The method according to claim 6, wherein the crosslinking agent is selected from compounds containing at least two vinyl groups; Preferably, the crosslinking agent is selected from divinylbenzene, allyl ether, diethyl diallyl malonate, diallyl disulfide, ethylene glycol diacrylate, ethylene glycol dimethyl Acrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4 - at least one of butanediol diacrylate and 1,4-butanediol dimethacrylate. 9. A quantum dot microsphere, characterized in that it is prepared by the preparation method according to any one of claims 1-8. 10. the application of quantum dot microsphere described in claim 9 in quantitative detection.

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