CN117031008A - Polymer modified micrometer magnetic bead and preparation method and application thereof - Google Patents

Description

A polymer-modified micron magnetic bead and its preparation method and application

Technical field

The invention belongs to the technical field of nanomaterials, and specifically relates to a polymer-modified micron magnetic bead and its preparation method and application.

Background technique

Cell screening is a very important operation in the fields of medicine, biology and other fields. Specific cells obtained through cell screening can be used for clinical diagnosis, tissue repair and cancer treatment (Wenjuan, S. et al. Food Research International, 2022, 162, 111952 -111952.). Therefore, efficient cell screening is of decisive significance for the therapeutic effect of cell therapy.

Currently common cell screening methods include density gradient centrifugation, flow sorting and immunomagnetic bead sorting. Density gradient centrifugation screens cells through centrifugal force. When using this method to screen cells, the centrifugation operation takes a long time, the operation is strict, and the separation efficiency is low. Flow sorting uses fluorescent markers to screen cells. The screened cells have high purity and high recovery rate, but the equipment is relatively expensive and cannot be promoted on a large scale. Immunomagnetic beads are a cell separation technology that has emerged in recent years. It uses the specific recognition between antigens and antibodies to quickly separate target cells. Using this method for sorting not only has high purity, good repeatability, and operation Simple and does not affect cell activity. The sorting column used for immunomagnetic bead sorting is a column material similar to a syringe, and its cavity is filled with magnetic beads that can amplify the magnetic field. When specifically labeled cells pass through the sorting column, the labeled cells are adsorbed to the magnetic microspheres in the chamber under an external magnetic field. The unlabeled cells will flow out first. After the unlabeled cells have finished flowing, the magnetic field will be removed. At this time, the sorting column will be eluted again. After the magnetic force disappears, the labeled cells will flow out.

In the sorting column, the magnetic microspheres used for cell screening should have good hydrophilicity, biocompatibility and paramagnetic properties at the same time. The surface of magnetic microspheres is usually improved by the embedding method. The coating liquid components and coating method are the key factors that determine the coating effect of magnetic microspheres and the performance of modified magnetic beads. Developing more polymer-modified microns with superior performance can provide more options for cell screening.

Contents of the invention

The object of the present invention is to provide polymer-modified micron magnetic beads with good dispersion and excellent hydrophilicity, biocompatibility and paramagnetic properties and a preparation method thereof.

Another object of the present invention is to provide a cell sorting column containing the above-mentioned polymer-modified micron magnetic beads.

Another object of the present invention is to provide the application of the above-mentioned polymer-modified micron magnetic beads or the above-mentioned cell sorting column in cell screening.

In order to achieve the above object, the technical solution adopted by the present invention is:

A kind of polymer-modified micron magnetic beads. The polymer-modified micron magnetic beads include bare magnetic beads and a polymer layer coated on the surface of the bare magnetic beads. The raw material of the polymer layer includes polyethylene glycol. , ethylene-vinyl acetate copolymer and leveling agent, the ratio of the feeding mass of the polyethylene glycol, ethylene-vinyl acetate copolymer and bare magnetic beads is (4~6): 1: (10~40), with Based on the sum of the masses of the polyethylene glycol and the ethylene-vinyl acetate copolymer, the amount of the leveling agent is 60 to 100 μL/g, such as 60 μL/g, 70 μL/g, 80 μL/g, 90 μL/g, 100 μL /g.

The polymer-modified micron magnetic beads of the present invention have excellent hydrophilicity and biocompatibility, and can be used as materials in direct contact with cells, and the polymer layer has little impact on the paramagnetic properties of bare magnetic beads, ensuring good Screening cell functions.

Preferably, the average molecular weight of the polyethylene glycol is 5500 to 6500, such as 5500, 5600, 5700, 5800, 5900, 6000, 6100, 6200, 6300, 6400, 6500.

Preferably, the number average molecular weight of the ethylene-vinyl acetate copolymer is 110-114.

Preferably, the bare magnetic beads are ferroferrite magnetic beads.

Preferably, the particle size of the bare magnetic beads is 300-600 μm.

Preferably, the leveling agent is polyether modified polydimethylsiloxane.

The invention also provides a method for preparing the above-mentioned polymer-modified micron magnetic beads. The polyethylene glycol, ethylene-vinyl acetate copolymer, bare magnetic beads and leveling agent are mixed in an organic solvent, and then the organic solvent is removed by rotary evaporation. , the obtained intermediate is baked and ultraviolet irradiated to obtain the polymer-modified micron magnetic beads.

In the present invention, the polymer layer is loaded on Fe ₃ O ₄ microspheres through the rotary evaporation method. The formed polymer layer is not only completely and uniformly wrapped, but also can reuse the solvent, improve the utilization rate, and reduce environmental pollution.

Preferably, after mixing the polyethylene glycol, ethylene-vinyl acetate copolymer, bare magnetic beads and leveling agent in an organic solvent, the cells are first disrupted using a cell disruptor, and then the rotary evaporation is performed.

Preferably, after the rotary evaporation is completed, the obtained intermediate is first washed with alcohol and then baked.

Preferably, the organic solvent is one or more of chloroform, dimethyl sulfoxide, ethanol or N,N-dimethylformamide.

Preferably, based on the sum of the masses of the polyethylene glycol and the ethylene-vinyl acetate copolymer, the amount of the organic solvent is 180 to 300 mL/g, such as 180 mL/g, 200 mL/g, 220 mL/g, 240 mL/g. g, 260mL/g, 280mL/g, 300mL/g.

Preferably, the rotary evaporation pressure is controlled to be 20-50KPa, the rotation speed is 100-400r/min, and the rotary evaporation temperature is 40-80°C.

Preferably, the baking temperature is controlled to be 40-90°C, such as 40°C, 50°C, 60°C, 70°C, 80°C, or 90°C.

Further preferably, the baking temperature is controlled to be 40-60°C.

Preferably, the baking time is controlled to be 1 to 8 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours.

Further preferably, the baking time is controlled to be 5 to 8 hours.

Preferably, the wavelength of ultraviolet irradiation is controlled to be 200-275nm and the power is 5w.

Preferably, the time of controlling ultraviolet irradiation is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

Further preferably, the time of controlling ultraviolet irradiation is 1 to 2 hours.

According to some specific and preferred embodiments, the preparation method includes the following steps:

(1) Dissolve polyethylene glycol and ethylene-vinyl acetate copolymer in an organic solvent to obtain solution A;

(2) Add a leveling agent to the solution S1 and stir evenly, use a cell disruptor to break the cells to obtain solution B;

(3) Add ferroferric oxide magnetic beads to the solution B, and rotary evaporate the organic solvent to obtain an intermediate;

(4) Use alcohol to wash the intermediate, then bake and ultraviolet irradiate the intermediate to obtain the polymer-modified micron magnetic beads.

Further preferably, in step (2), magnetic stirring is used, the stirring speed is controlled to 300-800 r/min, and the stirring temperature is 40-80°C.

Further preferably, in step (2), the power of the cell disrupter is controlled to be 50-100W.

Further preferably, in step (3), the pressure of the rotary evaporation is controlled to be 20-50KPa, the rotation speed is 100-400r/min, and the rotary evaporation temperature is 40-80°C.

Further preferably, in step (4), the alcohol is ethanol or methanol.

Further preferably, in step (4), the temperature of the baking is controlled to be 40-90°C, the baking time is controlled to be 1-8 hours, the wavelength of the ultraviolet radiation is controlled to be 200-275nm, and the power is controlled to be 4-275nm. 8w, control the UV irradiation time to 1~5h.

Further preferably, the rotary evaporation is performed in two steps. After the first rotary evaporation, ultrasonic mixing is used, and then the second rotary evaporation is performed. The ultrasonic power is controlled to be 10-30W and the time is 0.1-1h.

The present invention also provides a cell sorting column, which includes the above-mentioned polymer-modified micron magnetic beads or the polymer-modified micron magnetic beads prepared by the above-mentioned preparation method.

The present invention also provides the application of the above-mentioned polymer-modified micron magnetic beads or the above-mentioned polymer-modified micron magnetic beads prepared by the above-mentioned preparation method or the above-mentioned cell sorting column in cell screening.

The polymer micron magnetic beads of the present invention have good dispersion, excellent hydrophilicity and biocompatibility, can be used as materials in direct contact with cells, and have good paramagnetic properties, and can be used as immunomagnetic beads to screen the magnetic properties of cells. The medium can improve the efficiency and survival rate of cell screening and has broad application prospects in the field of cell screening.

The above-mentioned polymer micron magnetic beads have good biocompatibility, hydrophilicity and paramagnetic properties.

Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art:

The polymer-modified micron magnetic beads of the present invention include a polymer layer coated on the surface of the magnetic beads. The polymer layer is formed of a compound composition of PEG, EVA and leveling agent, which can provide a uniform and complete coating layer. The modified magnetic beads have better hydrophilicity and biocompatibility, and at the same time, the polymer layer has little impact on the paramagnetic properties of the magnetic beads, which can ensure the cell screening function of the modified magnetic beads. The present invention The polymer-modified micron magnetic beads have broad application prospects in the field of cell screening.

Description of the drawings

Figure 1 is a scanning electron microscope image of the polymer-modified micron magnetic beads prepared in Example 1;

Figure 2 is a mapping diagram of the polymer-modified micron magnetic beads prepared in Example 1;

Figure 3 is an elemental analysis diagram of the polymer-modified micron magnetic beads prepared in Example 1;

Figure 4 is a Fourier transform infrared analysis chart of the polymer-modified micron magnetic beads prepared in Example 1;

Figure 5 is a contact angle analysis diagram of the polymer-modified micron magnetic beads prepared in Example 1;

Figure 6 is a life and death staining diagram of mouse bone mesenchymal stem cells screened using polymer-modified micron magnetic beads prepared in Example 1;

Figure 7 is a hysteresis loop analysis diagram of the polymer-modified micron magnetic beads prepared in Example 1;

Figure 8 is an antioxidant graph of the polymer-modified micron magnetic beads prepared in Example 1.

Detailed ways

Nowadays, the commonly used method for surface modification of magnetic microspheres in industry is the encapsulation method. The magnetic particles are dispersed in a natural synthetic polymer solution, and the polymer layer is wrapped in the magnetic microspheres through physical means such as deposition, atomization, and ultrasound. on the ball. These processes are not easy to form a uniform film on the surface of the microspheres and also require the separation of impurities, which has great limitations. In addition, in previous research, the inventors also tried to use ultrasonic technology to wrap the polymer layer on the magnetic microspheres, but the coating effect was not ideal. Analyzing the reasons, one is that the power of the traditional ultrasonic instrument is not powerful enough, and the other is that the contact between the coating liquid and the magnetic beads under the ultrasonic process is not sufficient. Moreover, the ultrasonic process requires a large amount of solvent, the solvent cannot be recovered, and the cost is high.

Regarding the selection of coating liquid components, the inventor conducted a lot of research and experimental verification, and finally determined to use PEG and EVA as the main raw materials of the polymer layer, together with an appropriate amount of leveling agent. At the same time, the inventor also developed a method for preparing polymer magnetic microspheres. Different from the conventional coating mode, the inventor innovatively used a rotary evaporator for coating to fully contact the coating liquid with the magnetic microspheres, and also Solvent recycling and reuse can be achieved. Based on the good biocompatibility of PEG and the excellent adhesive properties of EVA, it adheres to the Fe ₃ O ₄ magnetic microspheres during the rotary evaporation process, thereby forming a polymer layer with uniform thickness. Through a large number of experimental characterizations, it has been proved that the polymer magnetic microspheres prepared by this method not only have a complete polymer layer coating on the surface, but also have good hydrophilicity and biocompatibility. More importantly, the polymer film prepared by this method minimally affects the paramagnetic properties of the magnetic microspheres, ensuring its good cell screening function. In general, the polymer microspheres prepared in the present invention are a candidate material that can be applied to magnetic sorting, and can be used in sorting columns as an important component of magnetic sorting cells.

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments.

In the following examples and comparative examples, the number average molecular weight of EVA is 114. The average molecular weight of PEG is 6000, and the iron sand is Fe ₃ O ₄ magnetic particles with a particle size of 450 to 500 μm. The leveling agent is polyether modified polydimethylsiloxane (BYK-333, Germany). The remaining reagents and instruments are commercially available products.

Examples 1 to 5, Comparative Examples 1 to 7

The amounts of EVA, PEG-6000, iron sand (Fe ₃ O ₄ ) and leveling agent used to prepare the polymer-modified micron magnetic beads of Examples 1 to 5 and Comparative Examples 1 to 7 are shown in Table 1 respectively.

Table 1

project EVA(g) PEG-6000(g) Iron sand(g) Leveling agent (μL) Example 1 0.05 0.2 2 20 Example 2 0.05 0.2 1.5 20 Example 3 0.05 0.2 1 20 Example 4 0.05 0.2 0.8 20 Example 5 0.05 0.3 0.5 20 Comparative example 1 2 0.2 2 20 Comparative example 2 0.5 0.5 0.5 10 Comparative example 3 0.4 0.5 0.5 10 Comparative example 4 0.3 0.5 0.5 10 Comparative example 5 0.2 0.5 0.5 10 Comparative example 6 0.05 0.5 0.5 10 Comparative example 7 0.05 0.4 0.5 10 Comparative example 8 0.05 0.3 0.5 10

The preparation methods of the polymer-modified micron magnetic beads of Examples 1 to 5 and Comparative Examples 1 to 7 are as follows:

(1) In a round-bottomed flask, dissolve PEG-6000 and EVA in 30 mL CHCl ₃ to obtain solution A.

(2) Add magnetic magnets and leveling agent to solution A, place it on a magnetic bead stirrer and stir the beads at 60°C for 60 minutes, with a stirring speed of 600 r/min, and then place it in a cell disrupter for ultrasonic treatment for 30 minutes. The ultrasonic power was 100W, and solution B was obtained.

(3) After removing the magnetic magnetons in solution B, add iron sand (Fe ₃ O ₄ ), and transfer it to a rotary evaporator for rotary evaporation. The parameters of the rotary evaporator are set to 30KPa, the rotation speed is 300r/min, and the rotary evaporation is carried out. The time is 0.5h, the temperature is 50°C, and then the solution after rotary evaporation is ultrasonicated for 0.2h with an ultrasonic power of 20W. Rotary evaporate again according to the above rotary evaporation conditions until there is no solvent. Use ethanol to wash both magnetic beads in the rotary evaporation bottle. Each time, the amount of ethanol used is 20 mL. Use a magnet to collect the washed magnetic beads to obtain the intermediate;

(4) After baking the intermediate in a 60°C oven for 5 hours, irradiate it under a UV lamp for 2 hours. The UV lamp wavelength is 245nm and the power is 5w to obtain polymer-modified micron magnetic beads.

Example 6

This embodiment provides a method for preparing polymer-modified micron magnetic beads, which is basically the same as Example 1. The only difference is that in step (1), the amount of CHCl ₃ is 50 mL.

Example 7

This embodiment provides a method for preparing polymer-modified micron magnetic beads, which is basically the same as Embodiment 1. The only difference is that in step (3) and step (4), the stirring rate of the rotary evaporator is 100 r/min.

Comparative example 9

This embodiment provides a method for preparing polymer-modified micron magnetic beads, which is basically the same as Example 1. The only difference is that in steps (3) and (4), the stirring rate of the rotary evaporator is 50 r/min.

Comparative example 10

This embodiment provides a method for preparing polymer-modified micron magnetic beads, which is basically the same as Example 1. The only difference is that the EVA in step (1) is replaced by chitosan.

Comparative example 11

This embodiment provides a method for preparing polymer-modified micron magnetic beads, which is basically the same as Example 1. The only difference is that the EVA in step (1) is replaced by sodium alginate.

The dispersibility of the polymer-modified micron magnetic beads prepared in the above examples and comparative examples is shown in Table 2.

project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Dispersion Evenly dispersed Evenly dispersed Evenly dispersed Evenly dispersed Evenly dispersed Evenly dispersed project Example 7 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Dispersion Evenly dispersed serious reunion serious reunion serious reunion Reunion is serious Reunion is serious project Comparative example 6 Comparative example 7 Comparative example 8 Comparative example 9 Comparative example 10 Comparative example 11 Dispersion Reunion is serious slight reunion slight reunion Reunion is serious serious reunion serious reunion

The polymer-modified micron magnetic beads prepared in each example and comparative example were taken out after ultraviolet irradiation, and their dispersion effects were observed.

As can be seen from Table 1, compared with the comparative example, the polymer-modified micron magnetic beads prepared in the examples have better dispersion, indicating that the polymer layer has high wrapping integrity. Comparing Examples 1 to 5 and Comparative Examples 1 to 8 shows that the ratio of EVA, PEG, magnetic beads and leveling agent has an impact on the dispersion of polymer-modified micron magnetic beads. If the EVA content is too high, the prepared polymer-modified micron magnetic beads will be agglomerated and wrapped unevenly, and the higher the EVA content, the more serious the agglomeration will be. Comparing Example 1, Example 7 and Example 9 shows that when other conditions remain unchanged, too low a rotation speed will cause the prepared polymer-modified micron magnetic beads to agglomerate and be unevenly wrapped.

Figure 1 is a scanning electron microscope picture of Example 1. From the characterization, it can be seen that the surface of the sphere is loaded with a uniform polymer layer. It shows that the polymer layer prepared by rotary evaporation is uniform and has complete coverage.

Figure 2 is a mapping picture of Example 1. From the characterization, it can be concluded that the protrusions on the surface of the sphere are polymer layers mainly composed of C and O elements, which further illustrates that the polymer layer is successfully loaded on the surface. The small amount of signal of Fe element on the surface of the sphere indicates that the high The molecular layer is not thick enough to block its signal.

Figure 3 shows the elemental analysis of Example 1. From the characterization, it can be concluded that the prepared polymer micron magnetic spheres are mainly composed of C, O, and Fe elements, which is consistent with expectations.

Figure 4 is the Fourier transform infrared characterization of Example 1. From the characterization, it can be seen that the characteristic peak at 1723 cm ^-1 is C=O; the characteristic peak at 1280 cm ^-1 is the characteristic peak of hydroxyl group; the characteristic peak at 1374 cm ^-1 is the characteristic peak of carboxyl group. peak. It shows that the surface of polymer micron magnetic spheres contains a large number of hydrophilic groups. These groups not only improve the hydrophilicity, but also provide effective functional groups for further modification, and have higher modification potential.

Figure 5 shows the contact angle characterization of Example 1. It can be seen from the characterization that when water droplets are dropped onto the surface of polymer-modified micron magnetic beads, the water droplets are immediately absorbed, which indicates that the surface is a super-hydrophilic organic substance. It further explains that the surface of the magnetic beads is wrapped with a complete polymer layer, which is conducive to cell adhesion and growth.

Figure 6 shows the dead and alive staining characterization of mouse bone mesenchymal stem cells screened using the polymer-modified micron magnetic beads prepared in Example 1. From the characterization, it can be seen that the prepared polymer-modified micron magnetic beads have good biological phase. Capacitive and flat cells indicate that the cells are in good growth status, can promote cell proliferation, and have the potential to be used as a magnetic medium for cell screening.

Figure 7 shows the hysteresis curve characterization of Example 1. It can be seen from the characterization that the prepared polymer-modified micron magnetic beads have good paramagnetic properties, reaching 100 emu/g, and have the ability to be used as a magnetic medium for cell screening.

Figure 8 shows the characterization of the anti-oxidation performance of Example 1. It can be seen from the characterization that the surface of the prepared polymer-modified micron magnetic beads is still smooth after soaking, indicating that it has good anti-oxidation and anti-rust properties.

In summary, the polymer-modified micron magnetic beads prepared in the examples have good dispersion, excellent hydrophilicity and biocompatibility, can be used as materials in direct contact with cells, have good paramagnetic properties, and can be used as immunomagnetic materials. Magnetic media for bead screening of cells. In addition, the polymer layer is loaded on Fe ₃ O ₄ microspheres through the rotary evaporation method. The formed polymer layer is not only completely and uniformly wrapped, but also can reuse the solvent, improving utilization and reducing environmental pollution.

The above embodiments are only for illustrating the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot limit the scope of protection of the present invention. All equivalent changes or modifications made based on the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A macromolecule modified micrometer magnetic bead is characterized in that: the high polymer modified micrometer magnetic bead comprises a naked magnetic bead and a high polymer layer coated on the surface of the naked magnetic bead, wherein the high polymer layer comprises polyethylene glycol, an ethylene-vinyl acetate copolymer and a flatting agent, and the ratio of the polyethylene glycol, the ethylene-vinyl acetate copolymer and the naked magnetic bead is (4-6): 1: (10-40), the consumption of the leveling agent is 60-100 mu L/g based on the mass sum of the polyethylene glycol and the ethylene-vinyl acetate copolymer.

2. The polymer modified micrometer magnetic bead according to claim 1, wherein: the average molecular weight of the polyethylene glycol is 5500-6000;

and/or the ethylene-vinyl acetate copolymer has a number average molecular weight of 110 to 114;

and/or, the bare magnetic beads are ferroferric oxide magnetic beads;

and/or the average particle diameter of the naked magnetic beads is 400-600 mu m;

and/or the leveling agent is polyether modified polydimethylsiloxane.

3. The method for preparing the polymer modified micrometer magnetic beads according to claim 1 or 2, characterized in that: mixing the polyethylene glycol, the ethylene-vinyl acetate copolymer, the bare magnetic beads and the flatting agent in an organic solvent, then removing the organic solvent by spin steaming, and baking and irradiating ultraviolet to obtain the high polymer modified micrometer magnetic beads.

4. A method of preparation according to claim 3, characterized in that: mixing the polyethylene glycol, the ethylene-vinyl acetate copolymer, the bare magnetic beads and the leveling agent in an organic solvent, crushing cells by using a cell crusher, and performing rotary evaporation;

and/or after the spin steaming is finished, the obtained intermediate is firstly washed by alcohol substances and then baked.

5. A method of preparation according to claim 3, characterized in that: the organic solvent is one or more of chloroform, dimethyl sulfoxide, ethanol or N, N-dimethylformamide;

and/or the use amount of the organic solvent is 180-300 mL/g based on the sum of the masses of the polyethylene glycol and the ethylene-vinyl acetate copolymer.

6. A method of preparation according to claim 3, characterized in that: controlling the pressure of the rotary steaming to be 20-50 KPa, the rotating speed to be 100-400 r/min and the rotary steaming temperature to be 40-80 ℃;

and/or controlling the baking temperature to be 40-90 ℃;

and/or controlling the baking time to be 1-8 hours;

and/or controlling the wavelength of ultraviolet irradiation to be 200-275 nm and the power to be 4-8 w;

and/or controlling the time of ultraviolet irradiation to be 1-5 h.

7. The method of manufacturing according to claim 4, wherein: the preparation method comprises the following steps:

(1) Dissolving polyethylene glycol and ethylene-vinyl acetate copolymer in an organic solvent to obtain a solution A;

(2) Adding a leveling agent into the solution S1, uniformly stirring, and crushing cells by using a cell crusher to obtain a solution B;

(3) Adding ferroferric oxide magnetic beads into the solution B, and removing the organic solvent by rotary evaporation to obtain an intermediate;

(4) Washing the intermediate by using an alcohol substance, and then baking and irradiating the intermediate by ultraviolet to obtain the macromolecule modified micrometer magnetic beads.

8. The method of manufacturing according to claim 7, wherein: in the step (2), magnetic stirring is adopted, the stirring speed is controlled to be 300-800 r/min, and the stirring temperature is controlled to be 40-80 ℃;

and/or, in the step (2), controlling the power of the cell disruption instrument to be 50-100W;

and/or, in the step (3), controlling the rotary steaming pressure to be 20-50 KPa, the rotary speed to be 100-400 r/min, and the rotary steaming temperature to be 40-80 ℃;

and/or the rotary steaming is carried out in two times, ultrasonic waves are used for uniformly mixing after the first rotary steaming is finished, and then the second rotary steaming is carried out, wherein the ultrasonic power is controlled to be 10-30W, and the time is 0.1-1 h;

and/or, in the step (4), the alcohol is ethanol or methanol;

and/or in the step (4), controlling the baking temperature to be 40-90 ℃, controlling the baking time to be 1-8 h, controlling the wavelength of ultraviolet radiation to be 200-275 nm, controlling the power to be 5w, and controlling the ultraviolet radiation time to be 1-5 h.

9. A cell sorting column, characterized in that: the cell sorting column comprises the polymer modified micrometer magnetic beads according to claim 1 or 2 or the polymer modified micrometer magnetic beads prepared by the preparation method according to any one of claims 3 to 8.

10. Use of the polymer modified micrometer magnetic beads according to claim 1 or 2 or the polymer modified micrometer magnetic beads prepared by the preparation method according to any one of claims 3 to 8 or the cell sorting column according to claim 9 in cell screening.