A method for preparing core-shell heterogeneous magnetic aggregation-induced luminescence fluorescent microspheres

Abstract

The present invention relates to a core-shell heterogeneous magnetic aggregation-induced luminescence fluorescent microsphere and a preparation method thereof. Aggregation-induced luminescence molecules, amphiphilic polymers and magnetic nanoparticles are self-assembled in one step by a microemulsion method, and the surface is carboxyl functionalized to obtain magnetic aggregation-induced luminescence fluorescent microspheres. The preparation method of the magnetic aggregation-induced luminescence fluorescent microspheres provided by the present invention is simple in process, and the prepared aggregation-induced luminescence fluorescent microspheres present a core-shell heterogeneous structure, and the magnetic shell layer is uniformly and sparsely distributed on the outside, and can retain fluorescence and magnetic properties to a large extent at the same time, and have the advantages of strong fluorescence signal, strong magnetism, complete morphology, good dispersibility, narrow particle size distribution, controllable particle size, easy surface modification, etc., and are suitable for ultrasensitive detection of trace target analytes in complex matrices, and have broad application prospects in clinical and on-site detection of emergencies, such as early screening of infectious diseases.

Description

Technical Field

[0001] The present invention belongs to the field of nano-synthesis and analysis application thereof, and specifically relates to a core-shell heterogeneous magnetic fluorescent microsphere based on aggregation-induced luminescence and a preparation method thereof. Background Art

[0002] Fluorescence analysis technology has been widely used in clinical diagnosis, food safety testing, environmental monitoring and other fields due to its advantages such as rapid sensitivity, good selectivity and convenient detection. Currently, commonly used fluorescent luminophores include organic fluorescent dyes, quantum dots, upconversion nanoparticles, etc. However, a single fluorescent luminophore as a signal probe often has a weak signal, and the relatively low detection sensitivity limits its application in ultrasensitive detection to a certain extent. In recent years, with the rapid development of nanoscience and technology, various new nanocarriers (such as mesoporous silica microspheres, polystyrene microspheres) or polymer assemblies have been reported to be used to load fluorescent luminophores and serve as detection probes to improve the detection sensitivity of fluorescence analysis. However, the fluorescence of traditional organic fluorescent dyes or quantum dots will be greatly weakened or even aggregation-induced quenching (ACQ) will occur at high concentrations or in an aggregated state, which greatly limits the loading amount of the fluorescent luminophore and the sensitivity of the probe, which to a certain extent restricts the application of fluorescent probes in the field of high-sensitivity analysis. In recent years, the "aggregation-induced emission" (AIE) phenomenon discovered by the research group of Academician Tang Benzhong of the Hong Kong University of Science and Technology has become a research hotspot in the field of fluorescence. Different from traditional aggregation-quenched organic fluorescent dyes, fluorescent dyes with aggregation-induced emission properties emit weak or even difficult to observe in dilute solution, but can emit bright fluorescence when aggregated in solution or in solid state. Due to the unique properties of solid-state emission, aggregation-induced emission fluorescent dyes solve the fluorescence quenching problem of traditional fluorescent luminescent bodies at high concentrations, which provides the possibility of increasing the loading capacity of fluorescent luminescent bodies and improving the sensitivity of fluorescence analysis.

[0003] In addition, nanoprobes face problems such as complex matrix environment, low target content, and background color interference in practical applications, which puts forward requirements for the development of multifunctional fluorescent nanoprobes. Among them, the "fluorescent-magnetic" dual-function nanoprobe has both fluorescence and superparamagnetism, and has very broad application prospects in the fields of biomarkers, separation and detection. At present, traditional "fluorescent-magnetic" nanoprobes are mainly prepared by in situ growth, layer-by-layer assembly, template embedding and other methods, and there are problems such as low fluorophore loading and low sensitivity. In addition, most "fluorescent-magnetic" nanoprobes present a "magnetic@fluorescent" nanostructure, and the outer nanolayer has a strong magnetic shielding effect on the magnetic core, which greatly weakens the magnetic function of the nanoprobe. In theory, using the magnetic component as the outer shell of the fluorescent nanoprobe to form a new type of "fluorescent@magnetic" core-shell heterostructure nanocomposite material can effectively circumvent the shielding effect of the magnetic component. In addition, by increasing the mass percentage of the fluorescent component, the fluorescence performance of the "fluorescent-magnetic" nanoprobe can be easily improved. Therefore, it is crucial to accurately control the spatial distribution of the fluorescent component and the magnetic component to construct an ideal "fluorescent@magnetic" core-shell heterostructure. Based on this, the present invention proposes a method for preparing size-controllable core-shell heterogeneous magnetic AIE fluorescent microspheres (magnetic aggregation-induced emission fluorescent microspheres). After searching, no public literature reports on the preparation of core-shell heterogeneous magnetic AIE fluorescent microspheres using a microemulsion method were found. Summary of the invention

[0004] The purpose of the present invention is to provide a method for stably preparing 100-1000nm magnetic AIE fluorescent microspheres. The prepared magnetic AIE fluorescent microspheres have the characteristics of high fluorescence intensity, high magnetism, core-shell heterogeneous structure, narrow particle size distribution, etc.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing core-shell heterogeneous magnetic fluorescent microspheres based on aggregation-induced luminescence comprises dissolving AIE single molecules with red emission, oleic acid-modified magnetic Fe3O4 nanoparticles and amphiphilic polymers in a good solvent, then adding an aqueous solution containing a surfactant, ultrasonically preparing the solution into a microemulsion, removing the good solvent in the microemulsion, redissolving the obtained precipitate in alkaline water for hydrolysis to obtain a carboxylated surface, redissolving the washed precipitate in a buffer solution to prepare magnetic aggregation-induced luminescence fluorescent microspheres (magnetic aggregation-induced luminescence fluorescent microspheres), and the preparation method comprises the following steps:

[0007] (1) Preparation of oleic acid modified magnetic Fe3O4 nanoparticles (OC-Fe3O4 NPs)

[0008] (a) First, 1.59g FeCl2·4H2O and 2.59g FeCl3 were dissolved in 150mL ultrapure water, nitrogen was introduced, and the mixture was heated to 50℃ and kept heated for 15min. Subsequently, 12.5mL NH3·H2O was added quickly at 500rpm and reacted for 30min, at which time the color of the solution changed from yellow to black. Then, the precipitate was collected under the action of an external magnetic field and washed with ultrapure water 5 times. The obtained precipitate was dissolved in 100mL ultrapure water under ultrasound. (b) Then, 1.2mL oleic acid was added and the suspension was stirred at 70℃ for 3h under nitrogen protection. Finally, the synthesized OC-Fe3O4NPs were washed three times with ethanol and resuspended in chloroform, and its mass concentration was determined for later use.

[0009] (2) Preparation of Magnetic Aggregation-Induced Luminescence Fluorescent Microspheres (Magnetic Aggregation-Induced Luminescence Fluorescent Microspheres)

[0010] Magnetic aggregation-induced luminescence fluorescent microspheres were prepared by microemulsion method. (a) AIE molecules and amphiphilic polymers were dissolved in good solvent chloroform, and surfactant sodium dodecyl sulfate (SDS) was dissolved in ultrapure water. The obtained SDS aqueous solution was added to the above chloroform mixed solution, and then oscillated and ultrasonicated to obtain a crude emulsion. (b) The obtained crude emulsion was ultrasonically treated with a cell disruptor, and then stabilized in ultrapure water to obtain a relatively stable "water-in-oil" microemulsion. (c) The obtained stable microemulsion was transferred to a rotary evaporator, and the chloroform was removed by a rotary evaporator to obtain a fixed magnetic aggregation-induced luminescence fluorescent microsphere, which was placed under an external magnetic field to remove the supernatant by magnetic attraction, and the precipitate was re-dissolved in alkaline water for surface hydrolysis. (d) The alkaline-hydrolyzed magnetic aggregation-induced luminescence fluorescent microspheres were magnetically washed and finally dispersed in a buffer solution. (e) By changing the volume of the chloroform phase and the aqueous phase, the concentration of SDS, the mass of the amphiphilic polymer, the ultrasonic power and time, magnetic aggregation-induced luminescence fluorescent microspheres with a diameter of 100-1000nm can be prepared. (f) The fluorescence and magnetic properties of magnetic aggregation-induced luminescence fluorescent microspheres can be regulated by adjusting the feeding amount of AIE and OC-Fe3O4NPs.

[0011] The present invention also provides a core-shell heterogeneous magnetic aggregation-induced luminescence fluorescent microsphere prepared by the above method, which presents an obvious core-shell heterogeneous structure, with AIE self-aggregation located in the inner core, and the magnetic shell layer of the magnetic Fe3O4 nanoparticles uniformly and sparsely distributed on the outer amphiphilic polymer shell surface, while greatly retaining the fluorescence and magnetic properties, and has strong fluorescence signal, strong magnetism, complete morphology, good dispersibility, narrow particle size distribution, controllable particle size, and easy surface modification.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] (1) The process for preparing magnetic aggregation-induced luminescence fluorescent microspheres used in the present invention is simple, does not require complex instruments, and takes a short time. In addition, the prepared aggregation-induced luminescence fluorescent microspheres present a core-shell heterogeneous structure and have the advantages of strong fluorescence signal, strong magnetism, complete morphology, good dispersibility, narrow particle size distribution, and controllable particle size.

[0014] (2) The present invention can adjust the particle size of the prepared magnetic aggregation-induced luminescence fluorescent microspheres by adjusting the oil phase volume, oil-water ratio, surfactant concentration, emulsification power and emulsification temperature to meet the needs of different application scenarios.

[0015] (3) The carboxylated surface of the polymer of the present invention can be used for direct biomodification coupling without further functionalization of functional groups. The magnetic function is suitable for ultrasensitive detection of trace target analytes in complex matrices and has broad application prospects in clinical and on-site detection of emergencies, such as early screening of infectious diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a transmission electron microscopy characterization of magnetic aggregation-induced emission fluorescent microspheres.

[0017] Figure 2 This is the fluorescence spectrum of magnetic aggregation-induced emission fluorescent microspheres.

[0018] Figure 3 This is a schematic diagram of the synthesis of magnetic aggregation-induced luminescence fluorescent microspheres prepared in the present invention. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention will be described in detail below. In order to avoid too many unnecessary details, the well-known structures or functions will not be described in detail in the following examples. Unless otherwise defined, the technical and scientific terms used in the following examples have the same meanings as those generally understood by technicians in the field to which the present invention belongs. The test reagents and consumables used in the following examples are all conventional chemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0020] Example 1 AIE@PMAO / Fe3O4NPs

[0021] The present invention provides a method for preparing oleic acid-modified magnetic Fe3O4 nanoparticles. First, water-soluble Fe3O4 nanoparticles are prepared, 1.59g FeCl2·4H2O and 2.59g FeCl3 are weighed and dissolved in 150mL ultrapure water, nitrogen is introduced, mechanical stirring is performed at 500rpm, and the mixture is heated to 50°C and kept heated for 15min. Subsequently, 12.5mL NH3·H2O is quickly added and reacted for 30min, at which time the color of the solution changes from yellow to black. Subsequently, the precipitate is collected under the action of an external magnetic field, washed with ultrapure water for 5 times, and the obtained precipitate is dissolved in 100mL ultrapure water under ultrasonic action. Subsequently, the obtained Fe3O4 nanoparticles are subjected to oleic acid treatment to convert them into an oil phase. 1.2mL oleic acid is added to the above-obtained precipitation solution, and the suspension is stirred at 70°C for 3h under nitrogen. Finally, the synthesized OC-Fe3O4 NPs were washed three times with ethanol and resuspended in chloroform to a final concentration of 0.3 mg mL -1 , stored at 4℃ for future use.

[0022] Example 2

[0023] The present invention provides a method for preparing magnetic aggregation-induced luminescence fluorescent microspheres. The magnetic aggregation-induced luminescence fluorescent microspheres prepared in this embodiment are AIE@PMAO / Fe3O4NPs, wherein the core AIE molecule is AIE, and the shell polymer is octadecene maleic anhydride polymer (PMAO). The preparation method is a microemulsion method. The synthesis method is as follows Figure 3 As shown, the specific preparation steps are:

[0024] (1) Weigh PMAO and dissolve it in chloroform to prepare a final concentration of 100 mg mL -1 . Prepare 0.2mg mL -1 Weigh 6 mg of AIE molecules and add 50 μL of 100 mg mL -1 PMAO solution, 20 μL 0.3 mg mL -1 Fe3O4NPs solution and 80μL chloroform were fully dissolved and mixed to obtain the oil phase. Then, 400μL 0.2mg mL -1 SDS was repeatedly shaken and sonicated until a homogeneous coarse emulsion was formed.

[0025] (2) The crude emulsion was further microemulsified by ultrasonic emulsification at 25°C for 5 minutes (on for 9.9 seconds; off for 5.5 seconds) using a cell disruptor with an emulsification power of 114 W. The obtained microemulsion was redissolved in 6 mL of ultrapure water to obtain a relatively stable "oil-in-water" microemulsion.

[0026] (3) Then transfer it to a rotary evaporator and perform rotary evaporation at 0.085 MPa for 30 minutes to remove the good solvent chloroform in the microemulsion to obtain solidified polymer microspheres. Remove the supernatant by magnetic attraction under an external magnetic field for 10 minutes, and redissolve it in 6 mL of alkaline water at pH = 10 and hydrolyze it for 24 hours to hydrolyze the acid anhydride of the polymer on the surface of the microspheres into carboxyl groups. Use ultrapure water and repeat centrifugation 3 times. Finally, redissolve the carboxylated aggregation-induced luminescence fluorescent microspheres in 6 mL of 0.01 M phosphate buffer at pH = 7.

[0027] like Figure 1 As shown, the prepared AIE@PMAO / Fe3O4NPs presents a uniform particle size distribution with a diameter distribution of about 250nm, and has an obvious core-shell heterogeneous structure, with AIE located inside the microsphere, using PMAO polymer as the shell layer, and Fe3O4NPs evenly distributed in the polymer shell layer. Compared with traditional magnetic fluorescent probes, the magnetic component of AIE@PMAO / Fe3O4NPs prepared in the present invention is located on the outside, which greatly reduces the shielding effect of the microsphere components on its magnetism and ensures excellent magnetic properties; moreover, the magnetic part occupies a small volume ratio, and the external magnetic shell is thin and sparse, which effectively reduces the fluorescence attenuation caused by the internal filtration effect. In addition, the internal AIE core occupies a large volume, has a high loading capacity, and has good fluorescence properties. As Figure 2 As shown, AIE@PMAO / Fe3O4NPs have a fluorescence spectrum shape consistent with that of AIE@PMAO NPs, and the fluorescence intensity is retained by 67%, which ensures high sensitivity for subsequent applications.

[0028] By changing the volume of the chloroform phase and the aqueous phase, the concentration of SDS, the mass of the amphiphilic polymer, the ultrasonic power and time, the magnetic aggregation-induced luminescence fluorescent microspheres with a diameter of 100-1000 nm can be prepared. By adjusting the amount of AIE and OC-Fe3O4NPs, the fluorescence and magnetic properties of the magnetic aggregation-induced luminescence fluorescent microspheres can be adjusted. The following will be demonstrated by examples.

[0029] Example 3

[0030] The present invention provides a method for preparing magnetic aggregation-induced luminescence fluorescent microspheres. The magnetic aggregation-induced luminescence fluorescent microspheres prepared in this embodiment are AIE@PMAO / Fe3O4NPs, and their particle size is about 100nm. The specific preparation steps are:

[0031] (1) Weigh 6 mg of AIE molecule and add 60 μL of 100 mg mL -1 PMAO solution, 20 μL 0.3 mg mL - 1Fe3O4NPs solution and 120μL chloroform were fully dissolved and mixed to obtain the oil phase. Then, 1000μL 2.5mg mL -1 SDS was repeatedly shaken and sonicated until a homogeneous coarse emulsion was formed.

[0032] (2) The crude emulsion was further microemulsified by ultrasonic emulsification at 25°C for 5 minutes (on for 9.9 seconds; off for 5.5 seconds) using a cell disruptor with an emulsification power of 114 W. The obtained microemulsion was redissolved in 6 mL of ultrapure water to obtain a relatively stable "oil-in-water" microemulsion.

[0033] (3) Then transfer it to a rotary evaporator and perform rotary evaporation at 0.085 MPa for 30 minutes to remove the good solvent chloroform in the microemulsion to obtain solidified polymer microspheres. Remove the supernatant by magnetic attraction under an external magnetic field for 10 minutes, and redissolve it in 6 mL of alkaline water at pH = 10 and hydrolyze it for 24 hours to hydrolyze the acid anhydride of the polymer on the surface of the microspheres into carboxyl groups. Use ultrapure water and repeat centrifugation 3 times. Finally, redissolve the carboxylated aggregation-induced luminescence fluorescent microspheres in 6 mL of 0.01 M pH = 7 phosphate buffer.

[0034] Example 4

[0035] The present invention provides a method for preparing magnetic aggregation-induced luminescence fluorescent microspheres. The magnetic aggregation-induced luminescence fluorescent microspheres prepared in this embodiment are AIE@PMAO / Fe3O4NPs with different magnetic component masses, and the particle size is about 250nm. The specific preparation steps are:

[0036] (1) Weigh 6 mg of AIE molecules and add 50 μL of 100 mg mL -1 PMAO solution, and add 7, 13, 27, 53 μL of 0.3 mg mL -1 OC-Fe3O4NPs solution, then 93, 87, 73, and 47 μL of chloroform were added to mix well to obtain the oil phase. Then, 400 μL of 0.2 mg mL -1 SDS was repeatedly shaken and sonicated until a homogeneous coarse emulsion was formed.

[0037] (2) The crude emulsion was further microemulsified by ultrasonic emulsification at 25°C for 5 minutes (on for 9.9 seconds; off for 5.5 seconds) using a cell disruptor with an emulsification power of 114 W. The obtained microemulsion was redissolved in 6 mL of ultrapure water to obtain a relatively stable "oil-in-water" microemulsion.

[0038] (3) Then transfer it to a rotary evaporator and perform rotary evaporation at 0.085 MPa for 30 minutes to remove the good solvent chloroform in the microemulsion to obtain solidified polymer microspheres. Remove the supernatant by magnetic attraction under an external magnetic field for 10 minutes, and redissolve it in 6 mL of alkaline water at pH = 10 and hydrolyze it for 24 hours to hydrolyze the acid anhydride of the polymer on the surface of the microspheres into carboxyl groups. Use ultrapure water and repeat centrifugation 3 times. Finally, redissolve the carboxylated aggregation-induced luminescence fluorescent microspheres in 6 mL of 0.01 M pH = 7 phosphate buffer.

[0039] Conclusion: The present invention successfully provides a method for preparing core-shell heterogeneous magnetic aggregation-induced luminescence fluorescent microspheres, which has a simple process, does not require complex instruments, and takes a short time. The prepared aggregation-induced luminescence fluorescent microspheres have the advantages of strong fluorescence signal, strong magnetism, complete morphology, good dispersibility, narrow particle size distribution, and controllable particle size. By adjusting the oil phase volume, oil-water ratio, surfactant concentration, emulsification power, and emulsification temperature, the particle size of the prepared magnetic aggregation-induced luminescence fluorescent microspheres can be adjusted to meet the needs of different application scenarios. The carboxylation surface of the polymer can be used for direct biomodification coupling without further functionalization of functional groups. The magnetic function is suitable for ultrasensitive detection of trace target analytes in complex matrices, and has broad application prospects in clinical and on-site detection of emergencies, such as early screening of infectious diseases.

[0040] The present invention can also use other polymers, good solvents and surfactants to prepare magnetic AIE microspheres. Therefore, the expansion and extension of the present invention based on other microsphere components are also within the scope of protection of the present invention. In addition, the present invention can also use AIE molecules with different fluorescent colors to prepare multicolor magnetic AIE microspheres for multi-channel detection applications. Therefore, the expansion and extension of the present invention based on other AIE molecules are also within the scope of protection of the present invention.

Claims

1. A method for preparing core-shell heterogeneous magnetic aggregation-induced luminescence fluorescent microspheres, characterized in that: Aggregation-induced emission molecules AIE, amphiphilic polymers and magnetic nanoparticles are self-assembled in one step by a microemulsion method, and their surfaces are carboxyl functionalized to obtain magnetic aggregation-induced emission fluorescent microspheres; specifically, the method comprises: dissolving AIE single molecules with red emission, oleic acid-modified magnetic Fe3O4 nanoparticles and amphiphilic polymers in a good solvent, adding a surfactant aqueous solution, and preparing the solution into a microemulsion; removing the good solvent in the microemulsion, and re-dissolving the obtained precipitate in alkaline water for hydrolysis to obtain a carboxyl surface, thereby obtaining magnetic aggregation-induced emission fluorescent microspheres; the method comprises the following steps: (1) Preparation of oleic acid modified magnetic Fe3O4 nanoparticles OC-Fe3O4 NPs; (2) Preparation of magnetic aggregation-induced luminescence fluorescent microspheres; (2-1) Weigh the amphiphilic polymer polymaleic anhydride-octadecene copolymer PMAO and dissolve it in chloroform to prepare a final concentration of 100-150 mg mL -1 ; Prepare 0.2-0.3 mg mL -1 6-12 mg of AIE molecules were weighed and 50-100 µL of 100 mg mL -1 PMAO solution, 20-40 µL 0.3 mg mL -1 OC-Fe3O4 NPs solution and 80-100 µL chloroform were fully dissolved and mixed to obtain the oil phase; then, 400-600 µL 0.2 mg mL -1 SDS, repeatedly shaken and sonicated until a homogeneous coarse emulsion is formed; (2-2) The crude emulsion is further microemulsified by using a cell disruptor for ultrasonic emulsification at 25°C for 5-10 minutes, with the power of 120-160 W, and the on-time of 9.9 seconds and the off-time of 5.5 seconds. The resulting microemulsion is redissolved in 6-12 mL of ultrapure water to obtain a relatively stable "oil-in-water" microemulsion. (2-3) Then, the microemulsion was transferred to a rotary evaporator and subjected to rotary evaporation at 0.085 MPa for 30 minutes to remove the good solvent chloroform in the microemulsion to obtain solidified polymer microspheres; the supernatant was removed by magnetic attraction under an external magnetic field for 10 minutes, and the microspheres were redissolved in 6-12 mL of alkaline water at pH = 10 and hydrolyzed for 24 hours to hydrolyze the acid anhydride of the polymer on the surface of the microspheres into carboxyl groups; ultrapure water was used and the microspheres were centrifuged repeatedly for 3 times; finally, the carboxylated aggregation-induced luminescence fluorescent microspheres were redissolved in 6-12 mL of 0.01 M phosphate buffer at pH = 7; (2-4) By changing the volume of the chloroform phase and the aqueous phase, the concentration of SDS, the mass of the amphiphilic polymer, the ultrasonic power and time, the magnetic aggregation-induced luminescence fluorescent microspheres with a diameter of 100-1000 nm can be prepared; (2-5) By adjusting the dosage of AIE and OC-Fe3O4 NPs, the fluorescence and magnetic properties of magnetic aggregation-induced luminescence fluorescent microspheres were regulated; The magnetic aggregation-induced luminescence fluorescent microspheres are AIE@PMAO / Fe3O4 NPs, which present an obvious core-shell heterogeneous structure, in which the AIE self-aggregation is located in the inner core, and the magnetic shell layer of the magnetic Fe3O4 nanoparticles is uniformly and sparsely distributed on the outer amphiphilic polymer PMAO shell surface.

2. The specific preparation method of a core-shell heterogeneous magnetic aggregation-induced emission fluorescent microsphere according to claim 1, characterized in that: The preparation of oleic acid modified magnetic Fe3O4 nanoparticles OC-Fe3O4 NPs comprises the following steps: (1-1) Dissolve 1.5-3.0 g FeCl2·4H2O and 2.5-5.0 g FeCl3 in 150-200 mL ultrapure water, introduce nitrogen protection, and heat to 50 °C for 15-30 min. (1-2) At a speed of 500 rpm, quickly add 12.5-25 mL NH3·H2O and react for 30-60 min. At this time, the color of the solution changes from yellow to black. (1-3) collecting the precipitate under the action of an external magnetic field and washing it with ultrapure water for 5 times; dissolving the obtained precipitate in 100-200 mL ultrapure water under the action of ultrasound; (1-4) Add 1.2-2.4 mL of oleic acid OC, stir the suspension at 70 °C for 3-6 h under nitrogen protection to synthesize OC-Fe3O4 NPs; (1-4) The synthesized OC-Fe3O4 NPs were washed three times with ethanol and resuspended in chloroform, and their mass concentration was determined for later use.

3. A core-shell heterogeneous magnetic aggregation-induced luminescence fluorescent microsphere prepared according to claim 1 or 2, characterized in that: The magnetic aggregation-induced luminescent fluorescent microspheres present an obvious core-shell heterogeneous structure, the AIE self-aggregation is located in the inner core, and the magnetic shell layer of the magnetic Fe3O4 nanoparticles is uniformly and sparsely distributed on the surface of the outer amphiphilic polymer shell layer.

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