A fluorescent microsphere with high refractive index, a tracer and a preparation method thereof

Abstract

The present application provides a fluorescent microsphere with a high refractive index, a tracer and a preparation method thereof. The micron-sized fluorescent microsphere is synthesized at one time, with good shaping and controllable particle size, and is applied to gas-phase and liquid-phase tracers with good detection effects. Among them, the preparation method of the fluorescent microsphere with a high refractive index includes the steps of: S1, alcoholyzing a titanium dioxide precursor or a zirconium dioxide precursor with an alcoholic solution of an acid to form a titanium dioxide alcoholysis sol or a zirconium dioxide alcoholysis sol, and mixing the titanium dioxide alcoholysis sol or the zirconium dioxide alcoholysis sol with a hydrophilic fluorescent material to form an aqueous solution; the oil-phase solution includes: an oily solvent, a water-in-oil surfactant and an inorganic particle stabilizer; S2, mixing the aqueous solution with the oil-phase solution and emulsifying the mixture; S3, carrying out a condensation reaction on the emulsified mixture to form a titanium dioxide shell layer or a zirconium dioxide shell layer coating the hydrophilic fluorescent material to obtain the fluorescent microsphere.

Description

Technical Field

[0001] This application belongs to the technical field of fluorescent microspheres. Specifically, it relates to a fluorescent microsphere with a high refractive index, a tracer, and a preparation method thereof. Background Art

[0002] Fluorescent microspheres are formed by encapsulating fluorescent materials inside the microspheres or connecting and fixing fluorescent substances on the surface of the microspheres. The fluorescent materials mainly include: organic fluorescent dyes, quantum dots, metal oxides, etc. These fluorescent materials are easily affected by the environment, such as being easily degraded, easily photo-bleached, not resistant to high temperature / strong light irradiation, not resistant to water and oxygen, etc. Therefore, in the prior art, most fluorescent materials are coated with inorganic shells or organic polymer shells. The fluorescent materials are excited by light or electricity and emit fluorescence. By virtue of different types of fluorescent components and different fluorescence contents, multiple different emission bands (colors) can be formed, which has the function of encoding. Therefore, they are widely used in the fields of biological labeling, disease diagnosis, tracers, solid-phase chips, liquid-phase chips, immunochromatography, Raman scattering, etc. As a tracer, fluorescent microspheres usually require a particle size in the micron range.

[0003] For example, fluorescent microspheres are used as tracers in the PIV particle image velocimetry technology. This technology spreads some tracer particles with good tracking or reflectivity in the flow field, irradiates the cross-sectional area of the measured flow field with a laser sheet light, continuously captures the particle images of two or more exposures through an imaging recording system, and then uses the image correlation method to analyze the captured PIV images to obtain the average displacement of the particle images in each small area, thereby determining the two-dimensional fluid velocity distribution of the entire area on the cross-section of the flow field. For example, quantum dots are coated with a silica shell to form micron-sized fluorescent microspheres, and lipophilic ligands are further modified on the shell surface, which can be used as tracers in the PIV particle image velocimetry technology. The synthesis of QD-SiO2 microspheres is usually the Stober method, and most of the synthesized silica fluorescent microspheres are nanoscale. If this method is used to prepare micron-sized silica fluorescent microspheres, a method of multiple layer-by-layer coating is required. This method has a long experimental design route and complex processes. Moreover, the QD-SiO2 microspheres use liquid paraffin / petroleum as the background, and their refractive index is similar to that of the background fluid. Only the point light source of the internal quantum dots can be seen in the QD-SiO2 microspheres, and the microsphere boundary is not clear (as Figure 1 shown), and the detection effect is not good.

[0004] In view of this, this application provides a fluorescent microsphere with a high refractive index, a tracer, and a preparation method thereof, which can synthesize micron-sized fluorescent microspheres at one time. The fluorescent microspheres have good formation and controllable particle size, and are applied to gas-phase and liquid-phase tracers with good detection effects. Summary of the Invention

[0005] The object of the present application is to provide a fluorescent microsphere with a high refractive index, a tracer and a preparation method thereof. The micron-sized fluorescent microsphere is synthesized at one time, has a good shape and controllable particle size, is applied to gas-phase and liquid-phase tracers, and has a good detection effect.

[0006] In the first aspect of the present application, a preparation method of a fluorescent microsphere with a high refractive index is provided, including the steps of:

[0007] S1, alcoholyzing a titanium dioxide precursor or a zirconium dioxide precursor with an acid alcohol solution to form a titanium dioxide alcoholysis sol or a zirconium dioxide alcoholysis sol, and mixing the titanium dioxide alcoholysis sol or the zirconium dioxide alcoholysis sol with a hydrophilic fluorescent material to form an aqueous solution; the oil-phase solution includes: an oily solvent, a water-in-oil surfactant, and an inorganic particle stabilizer;

[0008] S2, mixing the aqueous solution with the oil-phase solution and emulsifying the mixture;

[0009] S3, performing a condensation reaction on the emulsified mixture to form a titanium dioxide shell layer or a zirconium dioxide shell layer coating the hydrophilic fluorescent material, and obtaining a fluorescent microsphere.

[0010] In some embodiments, the acid alcohol solution is an acid solution dissolved in an alcohol solvent, the acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, or formic acid, and the alcohol solvent includes at least one of ethanol, methanol, isopropanol, and n-butanol.

[0011] Further, in the acid alcohol solution, the concentration of the acid solution is 0.05 - 0.3 mol / L.

[0012] Further, the mass ratio of the added acid alcohol solution to the titanium dioxide precursor or the zirconium dioxide precursor is 1:(1 - 6).

[0013] In some embodiments, during the alcoholysis of the titanium dioxide precursor or the zirconium dioxide precursor, a chelating agent is further added, and the chelating agent is used to control the alcoholysis rate of the titanium dioxide precursor or the zirconium dioxide precursor.

[0014] Further, the chelating agent includes at least one of acetylacetone, sodium oxalate, sodium citrate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, sodium tartrate, sodium gluconate, HEDTA, DEG, phytic acid, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, and dimercaprol.

[0015] Further, the mass ratio of the added chelating agent to the titanium dioxide precursor or the zirconium dioxide precursor is 1:(15 - 40).

[0016] In some embodiments, the titanium dioxide precursor includes at least one of tetrabutyl titanate, dibutyl titanate, and diethyl titanate, and the zirconium dioxide precursor includes at least one of zirconium propoxide and zirconyl chloride.

[0017] In some embodiments, the pH value of the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol is 5.5 - 7.5.

[0018] In some embodiments, a fluorescent material is modified with a hydrophilic ligand to form the hydrophilic fluorescent material.

[0019] Further, the hydrophilic ligand includes at least one of mercapto Tween, mercapto PEG, polyoxyethylene fatty acid ester, polyoxyethylene fatty alcohol ether, higher fatty alcohol sulfate, aliphatic sulfonate, and alkyl aryl sulfonate.

[0020] Further, in the aqueous solution, the mass ratio of the hydrophilic fluorescent material to the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol is 1:(10 - 100).

[0021] In some embodiments, the aqueous solution further includes a viscosity regulator, and the viscosity regulator adjusts the viscosity of the aqueous solution.

[0022] Further, in the aqueous solution, the mass proportion of the viscosity regulator is 0.1 - 20 wt%.

[0023] In some embodiments, the aqueous solution further includes a magnetic material, and in the aqueous solution, the mass proportion of the magnetic material is 1 - 50 wt%.

[0024] In some embodiments, in step S1, the oily solvent is an alkane solvent, and the oily solvent includes at least one of liquid paraffin, hexadecane, dodecane, tetradecane, cyclohexane, n-octanol, and n-decanol.

[0025] In some embodiments, the water-in-oil surfactant is a nonionic water-in-oil surfactant and its HLB value is 1.5 - 5.8. The water-in-oil surfactant includes a lipophilic segment and a hydrophilic segment. The hydrophilic segment includes one of polyethylene glycol, polyglycerol, and polyoxyethylene, and the lipophilic segment includes one of polyhydroxystearate, polycondensed ricinoleate, polyoxybutylene, polyoleate, and polyfatty acid ester.

[0026] Further, the hydrophilic segment includes one of polyethylene glycol, polyglycerol, and polyoxyethylene, and the lipophilic segment includes one of polyhydroxystearate, polycondensed ricinoleate, and polyoxybutylene.

[0027] Further, when the lipophilic chain segment of the water-in-oil surfactant is dimeric hydroxystearate, the hydrophilic chain segment is polyethylene glycol or polyglycerol. The water-in-oil surfactants include: polyethylene glycol (30) dimeric hydroxystearate (P135), polyglycerol-2 dimeric hydroxystearate (PGPH).

[0028] Further, when the lipophilic chain segment of the water-in-oil surfactant is polycondensed ricinoleic acid, the hydrophilic chain segment is polyglycerol. The water-in-oil surfactants include at least one of: polyglycerol-3 polyricinoleate, polyglycerol-4 polyricinoleate, polyglycerol-6 polyricinoleate, polyglycerol-10 polyricinoleate, polyethylene glycol-2 polyricinoleate.

[0029] Further, when the lipophilic chain segment of the water-in-oil surfactant is polyoleate or polyfatty acid ester, the hydrophilic chain segment is polyethylene glycol or polyglycerol. The water-in-oil surfactants include at least one of: diglycerol dioleate, hexaglycerol pentastearate, decaglycerol decaoleate.

[0030] Further, when the lipophilic chain segment of the water-in-oil surfactant is polyoxybutylene, the hydrophilic chain segment is polyoxyethylene. The water-in-oil surfactants include: polyoxyethylene-polyoxybutylene copolymer, polyoxyethylene-polyoxybutylene polyether.

[0031] In some embodiments, the inorganic particle stabilizer includes at least one of: magnesium hydroxide, hydroxyapatite, calcium pyrophosphate, calcium polyphosphate, silica, montmorillonite, carbon nanotubes.

[0032] Further, the inorganic particle stabilizer has a flake structure with an aspect ratio of 1:(1 - 10); the particle size of the inorganic particle stabilizer is 5 nm - 100 nm.

[0033] Further, the surface of the inorganic particle stabilizer is modified with a lipophilic ligand, and the lipophilic ligand includes: stearic acid or a silane coupling agent.

[0034] In some embodiments, in the oil phase solution, the mass ratio of the water-in-oil surfactant is 2 - 15 wt%; in the oil phase solution, the mass ratio of the inorganic particle stabilizer is 5 - 20 wt%.

[0035] In some embodiments, in step S2, the mass ratio of the aqueous phase solution to the oil phase solution is 1:

[0036] (10 - 80).

[0037] Further, an aqueous solution is added to an oil-phase solution at a rate of 1-20 ml per hour; the mixture is emulsified, including stirring the mixture at a speed of 100-1000 r / min for 10 min-240 min.

[0038] In some embodiments, in step S3, the emulsified mixture is catalytically treated to form a titanium dioxide shell or a zirconium dioxide shell coating the hydrophilic fluorescent material through a condensation reaction.

[0039] In some embodiments, the particle size of the fluorescent microspheres is 1-130 μm.

[0040] Further, the catalytic treatment includes at least one of adding a catalyst, heating, or vacuum distillation. The catalyst includes: ammonia water, triethylamine, and trioctylamine.

[0041] In a second aspect of the present application, a fluorescent microsphere with a high refractive index is provided, and the fluorescent microsphere is obtained by the aforementioned preparation method.

[0042] In some embodiments, the particle size of the fluorescent microspheres is 1-130 μm.

[0043] In a third aspect of the present application, a tracer is provided, and the tracer includes the aforementioned fluorescent microspheres and functional groups connected to the surface of the fluorescent microspheres. The tracer includes a biological tracer, a groundwater tracer, an oil tracer, and a gas-phase tracer.

[0044] In some embodiments, the biological tracer includes: fluorescent microspheres, hydrophilic functional groups and coupling functional groups connected to the surface of the fluorescent microspheres. The groundwater tracer includes: fluorescent microspheres, hydrophilic functional groups connected to the surface of the fluorescent microspheres. The oil tracer includes: fluorescent microspheres, lipophilic functional groups connected to the surface of the fluorescent microspheres.

[0045] In a fourth aspect of the present application, a preparation method of a tracer is provided, including the step of connecting the aforementioned fluorescent microspheres with a functional ligand.

[0046] The fluorescent microsphere with a high refractive index and its preparation method of the present application, compared with the prior art, have at least the following advantages:

[0047] (1) For the fluorescent microspheres of the present application, the shell layer is titanium dioxide or zirconium dioxide, and the refractive index of titanium dioxide or zirconium dioxide is high, about 2.7. The refractive index difference from gases such as air and liquids such as water and oil is very large. The light scattering at the microsphere interface is intense, the two-phase interface is clear, the visual effect is a surface light source, the light is soft, and the test effect is good.

[0048] (2) The micron-scale fluorescent microspheres of the present application are synthesized once, and the fluorescent microspheres have good formation. The present application separates the "hydrolysis reaction" from the "condensation reaction" and adopts the water-in-oil microdroplet method to synthesize micron-scale fluorescent microspheres at one time. At the same time, the research on water-in-oil surfactants is particularly important. The applicant has found that in addition to the HLB value of the water-in-oil surfactant being 1.5 - 5.8, it is a non-ionic water-in-oil surfactant, and the hydrophilic group of the water-in-oil surfactant includes: one of polyethylene glycol, polyglycerol, and polyoxyethylene, and the lipophilic group includes: one of polyhydroxystearate, polycondensed castor oil acid, polyoleate, polyfatty acid ester, and polyoxybutene. Only in this way can the emulsifying ability be strong while having a high group compatibility with the titanium dioxide precursor / zirconium dioxide precursor and the oily solvent of the present application, and a high component matching.

[0049] (3) The fluorescent microspheres of the present application have good formation and small particle size. On the basis of using the above water-in-oil surfactant, when combined with an inorganic particle stabilizer, the particle size of the microspheres can be made smaller. The inorganic particle stabilizer adheres to the surface of the microdroplet through its surface wettability, forming a thin film on the surface of the microdroplet. And the inorganic particle stabilizer system is a kinetic and thermodynamic stable system. Even if the surface tension and viscosity of the microdroplet change violently, the inorganic particle stabilizer maintains the volume of the microdroplet unchanged through its rigid structure. At the same time, the inorganic particle stabilizers have mutual forces with each other, preventing the aggregation between microdroplets. Even if two microdroplets come into contact, they will not stick or agglomerate, making the particle size of the synthesized fluorescent microspheres smaller.

[0050] (4) The fluorescent microspheres of the present application have controllable particle size. First, by selecting the type of water-in-oil surfactant, the particle size range of the microspheres can be controlled. For example, when synthesizing microspheres with an increasing particle size range from small to large, the following are selected in turn: polyethylene glycol polyhydroxystearate, polyglycerol polyhydroxystearate → polyglycerol ricinoleate → polyglycerol polyoleate. Second, by selecting to increase the inorganic particle stabilizer, the particle size of the microspheres can be further reduced. Third, by adjusting the concentration of the water-in-oil surfactant, the inorganic particle stabilizer, and the emulsification parameters (such as emulsification methods like ultrasonic and stirring, stirring speed and time), the particle size of the microspheres can be finely adjusted, making the particle size of the microspheres adjustable / controllable.

[0051] (5) The present application hydrolyzes the titanium dioxide precursor and the zirconium dioxide precursor with an acid alcohol solution to reduce the hydrolysis rate and form a stable and uniform titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol. Further, a chelating agent is added to control the alcoholysis rate to achieve a controllable alcoholysis rate.

[0052] (6) The preparation method of the fluorescent microspheres of the present application can synthesize fluorescent microspheres with a size of 1 - 130 microns without using microfluidic technology, with low production cost and high production efficiency. Description of the Drawings

[0053] In conjunction with the following attached Figure 1 When reading in conjunction with the following attached drawings, the above and other features of the present application will be more fully described. It can be understood that these drawings only depict several embodiments of the present application, and thus should not be considered as limiting the scope of the present application. By using the attached drawings, the present application will be described more clearly and in detail.

[0054] Figure 1 It is a fluorescence microscope picture of silica quantum dot microspheres in the prior art with liquid paraffin as the background.

[0055] Figure 2 It is a fluorescence microscope picture of the fluorescent microspheres of Example 1 of the present application.

[0056] Figure 3 It is a fluorescence microscope picture of the fluorescent microspheres of Example 2 of the present application.

[0057] Figure 4 It is a fluorescence microscope picture of the fluorescent microspheres of Example 3 of the present application.

[0058] Figure 5 It is a fluorescence microscope picture of the fluorescent microspheres of Comparative Example 1 of the present application.

[0059] Figure 6 It is a fluorescence microscope picture of the fluorescent microspheres of Comparative Example 2 of the present application. Detailed Description of the Invention

[0060] The following examples are described to assist in understanding the present application. The examples are not and should not be construed in any way as limiting the scope of protection of the present application.

[0061] As used herein, phrases such as "at least one (a)" when before or after a list of elements modify the entire list of elements and not individual elements of the list. Unless otherwise defined, all terms in the specification (including technical and scientific terms) may be defined as commonly understood by those skilled in the art. Terms defined in a common dictionary should be interpreted as having the same meaning as in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized manner or overly broadly, unless clearly defined. In addition, unless explicitly stated to the contrary, the phrases "comprising" and "including" when used in this specification indicate the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or their combinations. Therefore, the above phrases will be understood to mean including the stated elements, but not excluding any other elements. "A plurality" means two or more; "connected" means directly connected or indirectly connected.

[0062] As described in the background art, the synthesis of QD-SiO2 microspheres is usually the Stober method. Most of the synthesized silica fluorescent microspheres are nanoscale. If this method is used to prepare micron-scale silica fluorescent microspheres, it needs to be completed by using the method of multiple layer-by-layer coating. This method has a long experimental design route and complex process. Moreover, when the QD-SiO2 microspheres are applied to petroleum tracers, with petroleum or liquid paraffin with similar properties as the background, its refractive index is about 1.4, while the refractive indices of petroleum and liquid paraffin are 1.3 - 1.5. The refractive indices of the two are similar. Only the point light source of the internal quantum dots of the QD-SiO2 microspheres can be seen, the boundary of the microspheres is not clear, and the detection effect is not good.

[0063] In this application, a titanium dioxide or zirconium dioxide shell layer is used to coat the fluorescent material. The refractive index of the titanium dioxide or zirconium dioxide shell layer is high, about 2.7. For the fluorescent microspheres of this application, there are large differences in refractive index from gases such as air, and liquids such as water and petroleum. If the refractive indices of the dispersed phase and the continuous phase are closer (such as the QD-SiO2 microspheres and petroleum), when light passes through the dispersed phase from the continuous phase, the angle of refraction of the light is small, the interface between the two is less clear, the scattering of light inside the dispersed phase is less obvious, the boundary of the microspheres is not clear, and only the fluorescent materials such as quantum dots inside the microspheres can be observed. Its visual effect is a point light source, which is relatively dazzling and the detection effect is also not good. In this application, a dispersed phase with a large difference in refractive index from the continuous phase is used. The refraction of light at the interface is obvious, the light scattering is intense, the interface between the two phases is clear, its visual effect is a surface light source, the light is relatively soft, and the detection effect is also good.

[0064] In the first aspect of this application, a method for preparing a fluorescent microsphere with a high refractive index is provided, including the steps:

[0065] S1, alcoholize the titanium dioxide precursor or zirconium dioxide precursor with an acid-alcohol solution to form a titanium dioxide alcoholysis sol or a zirconium dioxide alcoholysis sol, and mix the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol with a hydrophilic fluorescent material to form an aqueous solution; the oil phase solution includes: an oily solvent, a water-in-oil surfactant, and an inorganic particle stabilizer;

[0066] S2, mix the aqueous solution with the oil phase solution and emulsify the mixture;

[0067] S3, perform a condensation reaction on the emulsified mixture to form a titanium dioxide shell layer or zirconium dioxide shell layer coating the hydrophilic fluorescent material, and obtain the fluorescent microsphere.

[0068] In some embodiments, the acid-alcohol solution is an acid solution dissolved in an alcohol solvent. The acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, or formic acid, and the alcohol solvent includes at least one of ethanol, methanol, isopropanol, and n-butanol.

[0069] In the alcohol solution of the acid, the concentration of the acid solution is 0.05 - 0.3 mol / L. The mass ratio of the added alcohol solution of the acid to the titanium dioxide precursor or zirconium dioxide precursor is 1:(1 - 6).

[0070] Generally, the titanium dioxide precursor and zirconium dioxide precursor are hydrolyzed with an acid such as hydrochloric acid. However, since the hydrolysis rate of the titanium dioxide precursor and zirconium dioxide precursor such as tetrabutyl titanate and zirconium propoxide is too fast, gels are easily produced rather than a uniformly dispersed sol. In the present application, the alcohol solution of the acid is uniquely used to alcoholyze the titanium dioxide precursor and zirconium dioxide precursor, reducing the hydrolysis rate of the titanium dioxide precursor and zirconium dioxide precursor and forming a stable and uniform titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol.

[0071] In some embodiments, during the alcoholysis of the titanium dioxide precursor or zirconium dioxide precursor, a chelating agent is further added, and the chelating agent is used to control the alcoholysis rate of the titanium dioxide precursor or zirconium dioxide precursor.

[0072] The chelating agent includes at least one of acetylacetone, sodium oxalate, sodium citrate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, sodium tartrate, sodium gluconate, HEDTA, DEG, phytic acid, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, and dimercaptopropanol.

[0073] The mass ratio of the added chelating agent to the titanium dioxide precursor or zirconium dioxide precursor is 1:(15 - 40).

[0074] During the hydrolysis of the titanium dioxide precursor or zirconium dioxide precursor, the present application further adds a chelating agent, and the alcoholysis rate of the titanium dioxide precursor or zirconium dioxide precursor is controlled according to the amount of the added chelating agent to achieve a controllable alcoholysis rate.

[0075] In some embodiments, the titanium dioxide precursor or zirconium dioxide precursor is mixed with the chelating agent, and then the alcohol solution of the acid is added dropwise, and stirred at room temperature for 1 - 72 h for alcoholysis to form a titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol. Preferably, it is stirred at room temperature for 10 - 24 h.

[0076] In some embodiments, the titanium dioxide precursor includes at least one of tetrabutyl titanate, dibutyl titanate, and diethyl titanate, and the zirconium dioxide precursor includes at least one of zirconium propoxide and zirconium oxychloride.

[0077] In some embodiments, the pH value of the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol is 5.5 - 7.5.

[0078] The basic pH regulator includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, phosphate buffer solution, and borate buffer solution. The titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol formed above has strong acidity and cannot directly add fluorescent materials such as quantum dots and fluorescein, because strong acids will have an adverse effect on fluorescent materials such as quantum dots and fluorescein, and even cause quenching of the fluorescent materials. Therefore, it is necessary to adjust the pH of the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol to 5.5 - 7.5, and then mix it with the fluorescent material.

[0079] In some embodiments, the fluorescent material is modified with a hydrophilic ligand to form the hydrophilic fluorescent material.

[0080] The fluorescent material includes at least one of fluorescent nanoparticles, fluorescent polymers, and organic fluorescent dyes. The fluorescent nanoparticles include at least one of quantum dots, metal oxide nanoparticles, nanorods, or nanosheets. The quantum dots include at least one of IIB-VIA group, IIIA-VA group, IVA-VIA group, IVA group, IB-IIIA-VIA group, VIII-VIA group, perovskite materials, and carbon quantum dots. For example, II-VI group compounds may include: CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, or a combination thereof. III-V group compounds may include: GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, InZnP, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or a combination thereof. The quantum dots include nanocrystals having a homogeneous or substantially homogeneous composition, such as a core, and heterogeneous nanocrystals, such as core / shell type quantum dots including a core and one or more shells surrounding the core. The shell is defined as the material surrounding the core and may include one or more shell layers. The metal oxides include: Zn, Cr, Co, Dy, Er, Eu, Fe, Gd, Gd, Pr, Nd, Ni, In, Pr, Sm, Tb, Tm, and combinations thereof. The fluorescent polymer has a functional group capable of emitting fluorescence (such as fluorescein, etc.) and monomers capable of polymerization reaction in its structure. The monomers polymerize with each other or polymerize with other non-fluorescent monomers to prepare the fluorescent polymer.Organic fluorescent dyes include: fluorescein (stilbenes, coumarins, fluorans, benzoxazoles, naphthalene diimides, thiophene dicarboxylic acid amides, polycyclic aromatic hydrocarbons, perylene tetracarboxylic diimides, etc.), aromatic polycyclic compounds, intramolecular charge transfer compounds, metal complex fluorescent materials, enzymes, rare earth metal chelates.

[0081] A "ligand" refers to any molecule or ion that can interact weakly or strongly with a quantum dot (e.g., through covalent interaction, ionic interaction, van der Waals interaction, or any other molecular interaction with the outer surface of the quantum dot).

[0082] The hydrophilic ligand contains hydrophilic groups, and the hydrophilic groups include at least one of carboxyl group, phosphate group, amino group, imino group, quaternary ammonium group, amide group, hydroxyl group, and aldehyde group. The hydrophilic ligands include: mercapto Tween, mercapto PEG, polyoxyethylene fatty acid ester, polyoxyethylene fatty alcohol ether, higher fatty alcohol sulfate, aliphatic sulfonate, alkyl aryl sulfonate. These hydrophilic ligands are preferred because not all hydrophilic ligands are applicable in this application. The hydrophilic ligand needs to be able to be stably dispersed in titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol, and can combine with titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol (containing alcohol hydroxyl or silicon hydroxyl), and cannot escape to the edge of the fluorescent microsphere during the subsequent condensation reaction.

[0083] Furthermore, in the aqueous solution, the mass ratio of the hydrophilic fluorescent material to the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol is 1:(10 - 100).

[0084] In some embodiments, the aqueous solution further includes a viscosity regulator, and the viscosity regulator adjusts the viscosity of the aqueous solution. In the aqueous solution, the mass proportion of the viscosity regulator is 0.1 - 20 wt%.

[0085] The viscosity regulators include: PEG20000 (polyethylene glycol 20000), Tween 80, PVA (polyvinyl alcohol), PVP (polyvinylpyrrolidone), celluloses, alginates, agarose, starch, xanthan gum.

[0086] The viscosity regulator is a water-soluble polymer, which can increase the viscosity of the aqueous solution. The higher viscosity of the aqueous solution makes it difficult for fluorescent materials such as quantum dots to agglomerate and improves the dispersibility; moreover, it is beneficial for the subsequent condensation reaction to form fluorescent microspheres with good morphology and uniform spherical shape.

[0087] In some embodiments, the aqueous solution further comprises: a magnetic material, and the mass percentage of the magnetic material in the aqueous solution is 1-50 wt%. The magnetic material includes: one or more of magnetite, iron oxide, nickel oxide, cobalt oxide, magnetite, iron oleate, ferric chloride, ferric sulfate, ferric nitrate, ferrous chloride tetrahydrate, ferric chloride hexahydrate, nickel ferrite, aluminum ferrite, manganese ferrite, zinc ferrite, cobalt ferrite, CoFe2O4, NiFe2O4, or MnFe2O4.

[0088] In some embodiments, in step S1, the oily solvent is an alkane solvent, and the oily solvent includes: at least one of liquid paraffin, hexadecane, dodecane, tetradecane, cyclohexane, n-octanol, and n-decanol.

[0089] In some embodiments, the water-in-oil surfactant is a nonionic water-in-oil surfactant and has an HLB value of 1.5-5.8. The water-in-oil surfactant includes a lipophilic segment and a hydrophilic segment. The hydrophilic segment includes: one of polyethylene glycol, polyglycerol, and polyoxyethylene. The lipophilic segment includes: one of polyhydroxystearate, polycondensed castor oil acid, polyoxybutylene, polyoleate, and polyfatty acid ester. Preferably, the hydrophilic segment includes: one of polyethylene glycol, polyglycerol, and polyoxyethylene. The lipophilic segment includes: one of polyhydroxystearate, polycondensed castor oil acid, and polyoxybutylene.

[0090] When the lipophilic segment of the water-in-oil surfactant is dimeric hydroxystearate, the hydrophilic segment is polyethylene glycol or polyglycerol. The water-in-oil surfactant includes: polyethylene glycol (30) dimeric hydroxystearate (P135), polyglycerol-2 dimeric hydroxystearate (PGPH).

[0091] When the lipophilic segment of the water-in-oil surfactant is polycondensed castor oil acid, the hydrophilic segment is polyglycerol. The water-in-oil surfactant includes: at least one of polyglycerol-3 polyricinoleate, polyglycerol-4 polyricinoleate, polyglycerol-6 polyricinoleate, polyglycerol-10 polyricinoleate, and polyethylene glycol-2 polyricinoleate.

[0092] When the lipophilic segment of the water-in-oil surfactant is polyoleate or polyfatty acid ester, the hydrophilic segment is polyethylene glycol or polyglycerol. The water-in-oil surfactant includes: at least one of diglycerol dioleate, hexaglycerol pentastearate, and decaglycerol decaoleate.

[0093] When the lipophilic segment of the water-in-oil surfactant is polyoxybutylene, the hydrophilic segment is polyoxyethylene. The water-in-oil surfactant includes: polyoxyethylene-polyoxybutylene copolymer, polyoxyethylene-polyoxybutylene polyether.

[0094] Generally, in order to form water-in-oil droplets, water-in-oil surfactants are selected. The smaller the HLB value (hydrophilic-lipophilic balance value) of the surfactant, the stronger its lipophilicity. However, in this application, it is not simply a matter of choosing a water-in-oil surfactant with a smaller HLB value. Common surfactants in the art are not applicable. For example, Span 80 has an HLB value of 4.3 and is also a non-ionic water-in-oil surfactant within the range of 1.5 - 5.8 of the HLB value in this application. However, using the preparation method of this application, the prepared fluorescent microspheres have a particle size of about 300 μm or more, and the structure of the fluorescent microspheres is unstable. After a large number of experiments, the applicant determined that in addition to the HLB value of the water-in-oil surfactant being 1.5 - 5.8 and being a non-ionic water-in-oil surfactant, the hydrophilic group of the water-in-oil surfactant includes one of polyethylene glycol, polyglycerol, and polyoxyethylene, and the lipophilic group includes one of polyhydroxystearate, polycondensed ricinoleic acid, polyoleate, polyfatty acid ester, and polyoxybutylene. Only in this way can the emulsifying ability be strong, and the group compatibility with the titanium dioxide precursor / zirconium dioxide precursor and the oily solvent in this application be high, and the component matching be high, so as to form fluorescent microspheres with good shape and small particle size. Selecting the type of water-in-oil surfactant can control the particle size range of the synthesized fluorescent microspheres. For example, when synthesizing microspheres with a particle size range from small to large, select in turn: polyethylene glycol polyhydroxystearate, polyglycerol polyhydroxystearate → polyglycerol ricinoleate → polyglycerol polyoleate, to achieve controllable particle size of the fluorescent microspheres.

[0095] In some embodiments, the inorganic particle stabilizer includes at least one of magnesium hydroxide, calcium hydroxyphosphate, calcium pyrophosphate, calcium polyphosphate, silicon dioxide, montmorillonite, and carbon nanotubes.

[0096] Furthermore, the inorganic particle stabilizer has a flake structure, and its aspect ratio is 1:(1 - 10); the particle size of the inorganic particle stabilizer is 5 nm - 100 nm.

[0097] Furthermore, the surface of the inorganic particle stabilizer is modified with a lipophilic ligand, and the lipophilic ligand includes: stearic acid, or a silane coupling agent.

[0098] In some embodiments, in the oil-phase solution, the mass ratio of the water-in-oil surfactant is 2 - 15 wt%; in the oil-phase solution, the mass ratio of the inorganic particle stabilizer is 5 - 20 wt%.

[0099] On the basis of using the above-mentioned water-in-oil surfactant, the present application further uses an inorganic particle stabilizer in combination, which can further reduce the particle size of the synthesized fluorescent microspheres. The inorganic particle stabilizer adheres to the surface of the microdroplets through its surface wettability, forming a thin film on the surface of the microdroplets, and the inorganic particle stabilizer system is a kinetically and thermodynamically stable system. Even if the surface tension and viscosity of the microdroplets change dramatically, the inorganic particle stabilizer maintains the volume of the microdroplets unchanged through its own rigid structure. At the same time, the inorganic particle stabilizer prevents the aggregation of microdroplets by having an interaction force with each other, and even if two microdroplets collide with each other, they will not adhere or agglomerate. The composite system is stable, and microspheres with smaller particle sizes can be synthesized, and the microspheres have high stability.

[0100] In some embodiments, in step S2, the mass ratio of the aqueous phase solution to the oil phase solution is 1:

[0101] (10-80).

[0102] Furthermore, the aqueous phase solution is added to the oil phase solution at a speed of 1-20 ml / hour; and the mixed solution is emulsified, including stirring the mixed solution at a speed of 100-1000 r / min for 10 min-240 min.

[0103] In some embodiments, in step S3, the emulsified mixed solution is subjected to a catalytic treatment to form a titanium dioxide shell layer or a zirconium dioxide shell layer covering the hydrophilic fluorescent material through a condensation reaction.

[0104] The titanium dioxide shell layer or the zirconium dioxide shell layer covers a single or multiple hydrophilic fluorescent materials. Preferably, the titanium dioxide shell layer or the zirconium dioxide shell layer covers multiple hydrophilic fluorescent materials.

[0105] In some embodiments, the particle size of the fluorescent microspheres is 1-130 um, and the particle size of the fluorescent microspheres is controllable.

[0106] Furthermore, the catalytic treatment includes at least one of adding a catalyst, heating, or reduced pressure distillation. The catalyst includes ammonia water, triethylamine, and trioctylamine.

[0107] In a second aspect of the present application, a high refractive index fluorescent microsphere is provided, wherein the fluorescent microsphere is obtained by the aforementioned preparation method.

[0108] In some embodiments, the particle size of the fluorescent microspheres is 1-130 um, and the particle size of the fluorescent microspheres is controllable.

[0109] In the third aspect of the present application, a tracer is provided. The tracer includes the aforementioned fluorescent microspheres and functional groups connected to the surface of the fluorescent microspheres. The tracer includes: biological tracers, groundwater tracers, petroleum tracers, and gas-phase tracers.

[0110] In some embodiments, the biological tracer includes: fluorescent microspheres, hydrophilic functional groups and coupling functional groups connected to the surface of the fluorescent microspheres. The applications of the biological tracer include: drug loading, biological probes, biological labeling, disease diagnosis, solid-phase chips, liquid-phase chips, and Raman scattering. The groundwater tracer includes: fluorescent microspheres, hydrophilic functional groups connected to the surface of the fluorescent microspheres. The petroleum tracer includes: fluorescent microspheres, lipophilic functional groups connected to the surface of the fluorescent microspheres.

[0111] The hydrophilic functional groups include at least one of carboxyl group, phosphate group, amino group, imino group, quaternary ammonium group, amide group, ether group, hydroxyl group, and aldehyde group. The lipophilic functional groups include hydrocarbon group, ester group, aromatic group, polyoxybutylene group, long-chain perfluoroalkyl group, and polysiloxane group. The coupling functional groups include amino group, carboxyl group, epoxy group, azide group, and aldehyde group. The components containing hydrophilic functional groups include at least one of acrylic acid, methacrylic acid, polyacrylic acid, polymethacrylic acid, itaconic acid, and maleic acid. The components containing coupling functional groups include at least one of glycidyl methacrylate, allyl glycidyl ether, epoxy polyethylene glycol acrylate, epoxy polyethylene glycol methacrylate, azide polyethylene glycol acrylate, azide polyethylene glycol methacrylate, aldehyde polyethylene glycol acrylate, aldehyde polyethylene glycol methacrylate, sodium 4,4'-di(azidostilbene)-2,2'-disulfonate tetrahydrate, acrolein, trans-2-pentenal, 3-(2-furyl)acrolein, 3-dimethylaminopropenal, 2-methylpropenal, and cinnamaldehyde.

[0112] In the fourth aspect of the present application, a method for preparing a tracer is provided, including the step of connecting the aforementioned fluorescent microspheres with a functional ligand. The method for connecting the fluorescent microspheres with the functional ligand can adopt the conventional methods of the existing technology.

[0113] The present invention will be further described in detail below with specific examples and comparative examples. However, the present invention is not limited to the following examples. The implementation conditions adopted in the examples can be further adjusted according to different requirements of specific uses. The conditions not specified are the conventional conditions in the industry.

[0114] Example 1:

[0115] Step S1: Prepare an aqueous solution and an oil-phase solution

[0116] In a glass bottle with a lid and a magnetic stir bar, add 2.5 ml of tetrabutyl titanate and 0.1 g of acetylacetone. During magnetic stirring, slowly add 0.5 ml of an ethanol solution of hydrochloric acid (hydrochloric acid concentration is 0.1 mol / L, the rest is ethanol). Cover the lid and stir magnetically at room temperature for 12 h (100 rpm) to form a titanium dioxide alcoholysis sol. At room temperature, add an aqueous sodium hydroxide solution to adjust the pH, and measure the pH value of the silicon dioxide hydrolysis sol to be 6.0. Add 0.1 ml of an aqueous solution of cadmium selenide red quantum dots (surface modified with mercapto Tween 80 ligand) at a concentration of 50 mg / ml, and stir magnetically until no quantum dot particles can be seen visually; then add 0.5 g of PEG20000 (polyethylene glycol 20000), and stir magnetically until evenly mixed to obtain an aqueous solution.

[0117] In a five-necked flask equipped with a thermometer, a mechanical stirrer paddle, a reflux condenser, a nitrogen inlet, and a feeding port, add 38.7 g of liquid paraffin, 5 g of polyethylene glycol (30) dimeric hydroxystearate (P135), and 1 g of silicon dioxide particle stabilizer (particle size is 6 nm). The stirrer paddle is stirred at room temperature until P135 is completely dissolved to obtain an oil phase solution.

[0118] Step S2: Emulsification

[0119] Slowly add the aqueous solution to the oil phase solution (in the above five-necked flask) at a rate of 10 ml / hour. The stirrer paddle is stirred at room temperature for 30 min at a stirring speed of 400 rpm to obtain water-in-oil micro-droplets by emulsification.

[0120] Step S3: Condensation reaction

[0121] Add a mixture of 0.2 g of triethylamine and 4.3 g of liquid paraffin to the five-necked flask in Step S2 at one time to start the reaction. The stirrer paddle is stirred at room temperature for 3 h at a stirring speed of 300 rpm to obtain fluorescent microspheres.

[0122] The stock solution containing fluorescent microspheres prepared in Example 1 is dropped onto a glass slide. Using a fluorescence microscope, measure the average particle size of its fluorescent microspheres to be 10 μm, and take a picture of it under the fluorescence microscope, as Figure 2 shown.

[0123] Example 2:

[0124] Example 2 is generally the same as Example 1, except that: adding 5 g of polyethylene glycol (30) dimeric hydroxystearate (P135) and 1 g of silicon dioxide particle stabilizer (particle size is 6 nm) is replaced by adding 5 g of polyglycerol-4 polyricinoleate (PGPR) and 0.8 g of magnesium hydroxide particle stabilizer (particle size 7 nm).

[0125] The stock solution containing fluorescent microspheres prepared in Example 2 was dropped onto a glass slide. Using a fluorescence microscope, the average particle size of its fluorescent microspheres was measured to be 24 μm, and a picture of it under the fluorescence microscope was taken, as Figure 3 shown.

[0126] Example 3:

[0127] Example 3 is substantially the same as Example 1, except that: adding 5 g of polyethylene glycol (30) dimeric hydroxystearate (P135) and 1 g of silica particle stabilizer (particle size 6 nm) was replaced by adding 5 g of diglycerol dioleate and 0.58 g of silica particle stabilizer (particle size 6 nm).

[0128] The stock solution containing fluorescent microspheres prepared in Example 3 was dropped onto a glass slide. Using a fluorescence microscope, the average particle size of its fluorescent microspheres was measured to be 51 μm, and a picture of it under the fluorescence microscope was taken, as Figure 4 shown.

[0129] Comparative Example 1:

[0130] Step S1: Prepare the aqueous phase solution and the oil phase solution

[0131] In a capped glass bottle with a magnetic stirrer, add 2.5 ml of tetrabutyl titanate. During magnetic stirring, dropwise add 0.5 ml of hydrochloric acid aqueous solution (hydrochloric acid concentration is 0.1 mol / L, the rest is water). Cover the bottle and stir magnetically at room temperature for 12 h (100 rpm) to form a titanium dioxide alcoholysis sol. At room temperature, add sodium hydroxide aqueous solution to adjust the pH, and the measured pH value of the silica hydrolysis sol is 6.0. Add 0.1 ml of 50 mg / ml cadmium selenide red quantum dot (surface modified with mercapto Tween 80 ligand) aqueous solution, and stir magnetically until no quantum dot particles can be seen visually to obtain the aqueous phase solution.

[0132] In a five-necked flask equipped with a thermometer, a mechanical stirrer paddle, a reflux condenser, a nitrogen interface, and a feeding port, add 38.7 g of liquid paraffin and 5 g of sorbitan monooleate (span80), and stir the stirrer paddle at room temperature until span80 is completely dissolved to obtain the oil phase solution.

[0133] Step S2: Emulsification

[0134] Slowly add the aqueous phase solution to the oil phase solution (in the above five-necked flask) at a rate of 10 ml / hour. The stirrer paddle stirs at room temperature for 30 min, and the stirring speed is 400 rpm to emulsify to obtain water-in-oil microdroplets.

[0135] Step S3: Condensation reaction

[0136] Into the five-necked flask in step S2, a mixture of 0.2 g of triethylamine and 4.3 g of liquid paraffin was added at one time, and the reaction was started. The stirring paddle was stirred at room temperature for 3 h at a stirring speed of 300 rpm to obtain fluorescent microspheres.

[0137] The stock solution containing fluorescent microspheres prepared in Comparative Example 1 was dropped onto a glass slide, and its picture was taken under a fluorescence microscope, as Figure 5 shown. From Figure 5 it can be seen that there are fluorescent aggregates with very large particle sizes and irregular shapes, indicating that the particle sizes of the fluorescent microspheres are too large and the shapes are not good.

[0138] Comparative Example 2:

[0139] Comparative Example 2 is generally the same as Comparative Example 1, except that: 5 g of sorbitan monooleate (span80) in step S1 of Example 1 was replaced with 5 g of polyglycerol monostearate.

[0140] The stock solution containing fluorescent microspheres prepared in Comparative Example 2 was dropped onto a glass slide, and its picture was taken under a fluorescence microscope, as Figure 6 shown. From Figure 6 it can be seen that there are fluorescent aggregates with very large particle sizes and irregular shapes, indicating that the particle sizes of the fluorescent microspheres are too large and the shapes are not good.

[0141] Although the present application has disclosed multiple aspects and embodiments, other aspects and embodiments will be obvious to those skilled in the art. Without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. The multiple aspects and embodiments disclosed in the present application are only used for illustration, and they are not intended to limit the present application. The actual protection scope of the present application is subject to the claims.

Claims

1. A preparation method of fluorescent microspheres, characterized in that, Including the steps of: S1. Alcoholyzing a titanium dioxide precursor or a zirconium dioxide precursor with an acid alcohol solution to form a titanium dioxide alcoholysis sol or a zirconium dioxide alcoholysis sol, where the pH value of the titanium dioxide alcoholysis sol or the zirconium dioxide alcoholysis sol is 5.5 - 7.5; mixing the titanium dioxide alcoholysis sol or the zirconium dioxide alcoholysis sol with a viscosity regulator and a hydrophilic fluorescent material to form an aqueous solution; In the aqueous solution, the mass proportion of the viscosity regulator is 0.1 - 20 wt%; The oil phase solution includes: an oily solvent, a water-in-oil surfactant, and an inorganic particle stabilizer; the water-in-oil surfactant is a nonionic water-in-oil surfactant and its HLB value is 1.5 - 5.

8. The water-in-oil surfactant includes a lipophilic segment and a hydrophilic segment. The hydrophilic segment includes one of polyethylene glycol, polyglycerol, and polyoxyethylene. The lipophilic segment includes one of polyhydroxystearate, polycondensed castor oil acid, polyoxybutylene, polyoleate, and polyfatty acid ester; S2. Mixing the aqueous solution with the oil phase solution and emulsifying the mixture; S3. Performing a condensation reaction on the emulsified mixture to form a titanium dioxide shell or a zirconium dioxide shell coating the hydrophilic fluorescent material, thereby obtaining fluorescent microspheres.

2. The preparation method of the fluorescent microspheres according to claim 1, characterized in that, The acid alcohol solution is an acid solution dissolved in an alcohol solvent. The acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, or formic acid. The alcohol solvent includes at least one of ethanol, methanol, isopropanol, and n-butanol.

3. The preparation method of the fluorescent microspheres according to claim 2, wherein, In the acid alcohol solution, the concentration of the acid solution is 0.05 - 0.3 mol / L.

4. The preparation method of the fluorescent microspheres according to claim 2, wherein, The mass ratio of the added acid alcohol solution to the titanium dioxide precursor or the zirconium dioxide precursor is 1:(1 - 6).

5. The preparation method of the fluorescent microspheres according to claim 1, wherein, During the alcoholysis of the titanium dioxide precursor or the zirconium dioxide precursor, a chelating agent is also added, and the chelating agent is used to control the alcoholysis rate of the titanium dioxide precursor or the zirconium dioxide precursor.

6. The preparation method of the fluorescent microspheres according to claim 5, wherein, The chelating agent includes at least one of acetylacetone, sodium oxalate, sodium citrate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, sodium tartrate, sodium gluconate, HEDTA, DEG, phytic acid, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, and dimercaptopropanol.

7. The method for preparing the fluorescent microspheres according to claim 5, wherein, The mass ratio of the added chelating agent to the titanium dioxide precursor or the zirconium dioxide precursor is 1:(15 - 40).

8. The preparation method of the fluorescent microspheres according to claim 1, characterized in that, Including one or more features selected from the following group: (1) The titanium dioxide precursor includes at least one of tetrabutyl titanate, dibutyl titanate, and diethyl titanate. The zirconium dioxide precursor includes at least one of zirconium n-propoxide and zirconyl chloride; (2) Modify the fluorescent material with a hydrophilic ligand to form the hydrophilic fluorescent material; the fluorescent material includes at least one of fluorescent nanoparticles, fluorescent polymers, and organic fluorescent dyes, and the fluorescent nanoparticles include at least one of quantum dots, metal oxide nanoparticles, nanorods, or nanosheets; the hydrophilic ligand includes: mercapto Tween, mercapto PEG, polyoxyethylene fatty acid ester, polyoxyethylene fatty alcohol ether, higher fatty alcohol sulfate, aliphatic sulfonate, alkyl aryl sulfonate; (3) In the aqueous solution, the mass ratio of the hydrophilic fluorescent material to the titanium dioxide alcoholysis sol or zirconium dioxide alcoholysis sol is 1:(10 - 100); (4) The viscosity regulator adjusts the viscosity of the aqueous solution; (5) The aqueous solution further includes: a magnetic material, and the mass fraction of the magnetic material in the aqueous solution is 1-50 wt%; (6) The oily solvent is an alkane solvent, and the oily solvent includes at least one of liquid paraffin, hexadecane, dodecane, tetradecane, cyclohexane, n-octanol, and n-decanol.

9. The preparation method of the fluorescent microspheres according to claim 1, wherein, When the lipophilic segment of the water-in-oil surfactant is dimerized hydroxy stearate, the hydrophilic segment is polyethylene glycol or polyglycerol; when the lipophilic segment of the water-in-oil surfactant is polycondensed castor oil acid, the hydrophilic segment is polyglycerol; when the lipophilic segment of the water-in-oil surfactant is polyoleate or polyfatty acid ester, the hydrophilic segment is polyethylene glycol or polyglycerol; when the lipophilic segment of the water-in-oil surfactant is polyoxybutylene, the hydrophilic segment is polyoxyethylene.

10. The preparation method of the fluorescent microspheres according to claim 1, characterized in that, The inorganic particle stabilizer includes at least one of magnesium hydroxide, hydroxyapatite, calcium pyrophosphate, calcium polyphosphate, silica, montmorillonite, and carbon nanotubes.

11. The preparation method of the fluorescent microspheres according to claim 10, characterized in that, The inorganic particle stabilizer has a flake structure, and its aspect ratio is 1:(1 - 10); the particle size of the inorganic particle stabilizer is 5 nm - 100 nm.

12. The preparation method of the fluorescent microspheres according to claim 10, wherein The surface of the inorganic particle stabilizer is modified with a lipophilic ligand, and the lipophilic ligand includes: stearic acid or a silane coupling agent.

13. The preparation method of the fluorescent microspheres according to claim 1, characterized in that, In the oil phase solution, the mass fraction of the water-in-oil surfactant is 2-15 wt%; in the oil phase solution, the mass fraction of the inorganic particle stabilizer is 5-20 wt%; in step S2, the mass ratio of the aqueous solution to the oil phase solution is 1:(10 - 80).

14. The preparation method of the fluorescent microspheres according to claim 1, characterized in that, In step S3, subject the emulsified mixture to catalytic treatment, and a condensation reaction forms a titanium dioxide shell or a zirconium dioxide shell coating the hydrophilic fluorescent material.

15. A fluorescent microsphere, characterized in that, The fluorescent microspheres are obtained by using the preparation method according to any one of claims 1-14.

16. A tracer, characterized in that, The tracer includes the fluorescent microspheres according to claim 15 and functional groups connected to the surface of the fluorescent microspheres, and the tracer includes biological tracers, groundwater tracers, petroleum tracers, and gas phase tracers.

17. The tracer according to claim 16, wherein, The biological tracers include: fluorescent microspheres, hydrophilic functional groups and coupling functional groups connected to the surface of the fluorescent microspheres; the groundwater tracers include: fluorescent microspheres, hydrophilic functional groups connected to the surface of the fluorescent microspheres; the petroleum tracers include: fluorescent microspheres, lipophilic functional groups connected to the surface of the fluorescent microspheres.

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