Preparation method of microgel based on magnetic field

Abstract

The invention discloses a preparation method of microgel based on a magnetic field, which specifically comprises the following steps: under the action of the magnetic field, adding superparamagnetic polymer molecules under the guidance of magnetic field force to overcome the surface tension between liquid drops and a needle, and self-assembling to form the microgel. The magnetic field preparation technology is utilized, many limitations of a traditional microgel preparation method are overcome, remarkable progress is made in the aspects of biocompatibility, preparation efficiency, structural controllability, equipment simplification and the like, and the magnetic field microgel has huge application potential and market prospects in the fields of drug delivery, cell culture, tissue engineering and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological and medical materials, and particularly relates to a preparation method of magnetic microgels. Background Art

[0002] As an advanced material, microgels have shown broad application prospects in the fields of biomedicine and tissue engineering. Microgels not only provide an excellent three-dimensional microenvironment required for cell growth and function maintenance, but also can be manipulated in response to external stimuli, thus achieving excellent application capabilities in complex biological environments. As a delivery carrier, microgels can achieve the controlled release of various biomolecules, including cells, proteins, and RNAs, etc. Microgels can also have high targeting properties, capable of precisely delivering drugs or biomolecules to the target site, improving the therapeutic effect and reducing side effects on non-target areas. At the same time, through external stimuli or internal molecular gradient regulation, microgels can achieve the sustained release of drugs, ensuring a long-term therapeutic effect, and most of their materials have good biocompatibility, avoiding immune responses and side effects in traditional delivery methods. In the field of tissue engineering, the application of microgels is also remarkable, specifically including aspects such as cytoskeleton construction, 3D printing inks, and scaffold materials. Microgels can act as extracellular matrix mimics to construct cytoskeletons, support cell growth and differentiation, and promote tissue regeneration and repair. The directionally oriented bionic structures constructed by microgels can guide the directional migration and growth of cells, supporting cell alignment and structure generation in tissue engineering. With its unique multifunctionality and broad application prospects, microgels have significantly promoted the development of the biomedical field, demonstrating their excellent performance and potential in drug delivery, tissue engineering, and other biomedical applications.

[0003] However, existing microgel preparation methods generally have limitations such as low preparation efficiency, complex equipment setup, and poor controllability of microgels, which restrict the wide application of microgels. For example, although the traditional centrifugation method can be used for microgel preparation, its preparation efficiency is low, and the size and morphology of microgels depend on the performance of centrifugation equipment, making it difficult to achieve precise regulation and restricting its application in complex biological environments.

[0004] As an emerging preparation technology, the microfluidic method has improved the preparation throughput, but it usually requires the use of toxic or poorly biocompatible oil phases to assist in the surface tension cutting of the hydrogel phase, resulting in limitations in the biocompatibility of the finally obtained hydrogel. In addition, the setup cost of microfluidic devices is high and the design is complex, increasing the barriers to application.

[0005] The electrospray method has received attention in microgel preparation. However, this method requires reliance on high-voltage power supplies and precise nozzle designs, suffering from problems of high equipment costs and complex designs, which restricts its popularization in practical applications.

[0006] The gas shearing method shows certain advantages in optimizing the preparation process and biocompatibility of microgels. However, this method still faces technical challenges. Specifically, this method requires the use of specially prepared coaxial needles and relies on the precise control of high-flow-rate gases, both of which increase the complexity of equipment design and significantly enhance the difficulty and professionalism of microgel preparation. Therefore, there is an urgent need for an efficient, simple, and environmentally friendly microgel preparation method to meet the application requirements in fields such as biomedicine and tissue engineering. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0008] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0009] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing magnetic microgels.

[0010] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing magnetic microgels, characterized in that it includes:

[0011] Mixing a polymer material and magnetic nanoparticles evenly to obtain a magnetoresponsive hydrogel solution;

[0012] Prepare a magnet, place a receiving bath above the magnet, and then erect a stable syringe and needle vertically above it to build a microgel preparation device;

[0013] Put the magnetoresponsive hydrogel solution into the syringe, and by extruding the magnetoresponsive hydrogel solution in the syringe, make hydrogel droplets form at the needle tip. The hydrogel droplets are rapidly dropped into the receiving bath under the action of a magnetic field, thus obtaining microgels.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: the polymer material is at least one of sodium alginate, chitosan, and carboxymethyl cellulose.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the magnetic nanoparticles are superparamagnetic iron oxide nanoparticles.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: the concentration of superparamagnetic iron oxide nanoparticles in the magnetoresponsive hydrogel solution is 0.01-99.9 wt%.

[0017] As a preferred embodiment of the preparation method of the present invention, wherein: the receiving bath is a solution that matches the polymer material and can trigger a rapid cross-linking reaction with the polymer material.

[0018] As a preferred embodiment of the preparation method of the present invention, wherein: the magnet is a permanent magnet with a remanence greater than 1.1 T or an electromagnet.

[0019] As a preferred embodiment of the preparation method of the present invention, wherein: a stable syringe and a needle are erected vertically above, and the vertical distance between the end of the needle and the magnet is 0.2 - 5 cm.

[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide a microgel, characterized in that: the morphology and size of the microgel are controllable.

[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of the microgel.

[0022] Advantages of the present invention:

[0023] (1) Significantly improved biocompatibility: Traditional methods often require the use of oils, surfactants, or toxic chemical reagents when preparing microgels, which may lead to biocompatibility problems. The method of the present invention avoids the use of these substances, making the preparation process more environmentally friendly and significantly improving the biocompatibility of the microgels, which is particularly important for biomedical applications.

[0024] (2) Improved preparation efficiency: In the prior art, the preparation of microgels often involves multiple complex steps, which is time-consuming and inefficient. The present invention uses a magnetic field and a minimalist preparation process to accelerate the preparation speed and improve the preparation efficiency, which is of great significance for large-scale production and practical applications.

[0025] (3) Controllable microgel structure: Microgels prepared by traditional methods may have non-uniformity in structure, and it is difficult to precisely control the size distribution. The present invention uses the precise guidance of magnetic force to make the obtained microgel structure more controllable, and the size distribution has high controllability. In addition, the uniform distribution of magnetic nanoparticles in the microgel also ensures the stability and consistency of the magnetic response, providing a reliable guarantee for subsequent applications.

[0026] (4) Simplified equipment and wide applicability: Compared with the prior art, the method of the present invention does not require the construction of complex preparation equipment, and the operation is simple and easy. At the same time, this method is applicable to a variety of polymer materials, showing wide applicability, providing convenience for research and applications in different fields. Description of the Drawings

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0028] Figure 1 It is a schematic diagram of the principle for preparing microgels using a magnetic field in the embodiments of the present invention.

[0029] Figure 2 It is a simulated diagram of the magnetic field intensity distribution at different distances from the magnet.

[0030] Figure 3 It is a simulated diagram of the magnetic flux density of a cylindrical neodymium iron boron.

[0031] Figure 4 It is a process diagram (side view) of preparing microgels (microspheres) using a magnetic field in the embodiments of the present invention, with a scale of 1 cm.

[0032] Figure 5 It is a process diagram (45° top view) of preparing microgels (microspheres) using a magnetic field in the embodiments of the present invention, with a scale result of 1 cm.

[0033] Figure 6 It is a real - picture display of preparing microgels (microspheres) using a magnetic field in the embodiments of the present invention, with a scale of 500 μm.

[0034] Figure 7 It is a statistical chart of the standardized particle size distribution of microgels (microspheres).

[0035] Figure 8 It is a process diagram of preparing continuous microgels (microfibers) using a magnetic field in the embodiments of the present invention, with a scale of 1 cm.

[0036] Figure 9 It is a statistical chart of the relationship between the distance (H) between the needle and the magnet and the size of the microgels.

[0037] Figure 10 It is a statistical chart of the relationship between the concentration of SPIONs and the size of the microgels.

[0038] Figure 11 It is a biocompatibility test of preparing microgels using a magnetic field, with a scale of 200 μm; among them, PI represents propidium iodide, and Calcein - AM represents calcein acetoxymethyl ester. Detailed implementation manners

[0039] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific implementation manners of the present invention in combination with the embodiments of the specification.

[0040] In the following description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0041] Secondly, the so-called "one embodiment" or "embodiment" refers to specific features, structures, or characteristics that may be included in at least one implementation of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that are mutually exclusive of other embodiments.

[0042] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly commercially available.

[0043] Example 1

[0044] This embodiment provides a method for preparing microgels, comprising the following steps:

[0045] (1) Material preparation:

[0046] Polymer material: a hydrogel material with good biocompatibility;

[0047] Magnetic nanoparticles: superparamagnetic iron oxide nanoparticles (SPIONs);

[0048] Receiving bath: a solution that matches the polymer material and can trigger a rapid cross-linking reaction with the polymer material.

[0049] (2) Preparation of a magnetoresponsive hydrogel solution:

[0050] Mix the hydrogel material with SPIONs to prepare a hydrogel solution containing magnetic components, and then add double-distilled water and stir with a magnetic stirrer at 800 rpm to promote the uniform dispersion of the nanoparticles.

[0051] (3) Setup and preparation of the device:

[0052] Prepare a neodymium iron boron magnet with a remanence greater than 1.1 T. Place the receiving bath above the magnet, and then erect a stable syringe and needle vertically above it to obtain the device for preparing microgels using a magnetic field in this embodiment.

[0053] (4) Microgel preparation:

[0054] By extruding the hydrogel solution in the syringe, hydrogel droplets are formed at the needle tip. Under the precise guidance of magnetic force, the hydrogel droplets are quickly dripped into a preset receiving bath. The receiving bath contains a crosslinking agent, which can trigger a rapid crosslinking reaction at the moment when the droplets are dripped, forming microgels with uniform structure and excellent properties. By precisely controlling the magnetic field conditions, a high degree of controllability of the size and shape of the microgels can be achieved. By adjusting the distance between the needle and the magnet, the magnetic field strength and direction can be adjusted, and by controlling the extrusion speed of the needle, it is ensured that the droplets are quickly and precisely dripped under the guidance of magnetic force.

[0055] Refer to Figures 1 to 7 , Figure 1 which is a schematic diagram of the principle for preparing microgels using magnetic fields in this embodiment. Among them, F surface represents the surface tension acting on the droplet; F magnetic represents the magnetic force on the droplet in the magnetic field; F g represents the gravity acting on the droplet. By extruding the magnetoresponsive hydrogel solution in the syringe, hydrogel droplets are formed at the needle tip. Since the droplets contain SPIONs, they quickly converge under the action of magnetic force and overcome the surface tension. Under the precise guidance of magnetic force, the hydrogel droplets are quickly dripped into the receiving bath. The receiving bath immediately undergoes a crosslinking reaction with the polymer material in the hydrogel, causing the droplets to quickly solidify and form microgels.

[0056] Figure 2 is a simulation diagram of the magnetic field strength distribution at different distances from the magnet, Figure 3 is a simulation diagram of the magnetic flux density of a cylindrical neodymium iron boron magnet. It can be seen the variation of the magnetic response intensity gradient in the radial direction of the magnetic field and the variation of the magnetic flux density.

[0057] Figures 4 to 6 is a process diagram and actual diagram display for preparing microgels using magnetic fields in the embodiment of the present invention, Figure 7 is a statistical chart of the standardized particle size distribution of microgels (microspheres). It can be seen that the present invention can prepare microgels with uniform size without relying on complex equipment using magnetic fields.

[0058] Example 2

[0059] This embodiment provides a method for preparing sodium alginate microgels using magnetic fields, including the following steps:

[0060] (1) Material preparation:

[0061] Polymer material: 0.2 g of sodium alginate;

[0062] Magnetic nanoparticles: 2 g of SPIONS;

[0063] Receiving bath: Weigh 100 g of calcium chloride and dissolve it in 1 L of double-distilled water to prepare a 10% w / v calcium chloride solution as the receiving bath.

[0064] (2) Preparation of magnetoresponsive hydrogel solution:

[0065] Mix sodium alginate with SPIONs, add 20 mL of double-distilled water to prepare a hydrogel solution of 1 wt% sodium alginate and 10 wt% SPIONs, and stir with a magnetic stirrer at 800 rpm to ensure the uniform dispersion of SPIONs in the sodium alginate solution, forming a magnetoresponsive hydrogel solution.

[0066] (3) Setup and preparation of the device:

[0067] Select a cylindrical radial NS neodymium iron boron magnet with a radius of 3 cm. Place a petri dish containing calcium chloride solution above the magnet as the receiving bath, control the liquid level height not to exceed 0.2 cm, then erect a stable syringe and needle vertically above, adjust the vertical distance between the end of the needle and the magnet to 1 cm, and set the extrusion speed of the needle to 5 mL / min.

[0068] (4) Preparation of microgels:

[0069] Extrude the magnetoresponsive hydrogel solution in the syringe to form hydrogel droplets at the needle tip. Under the precise guidance of the magnetic field force, the hydrogel droplets quickly drop into the calcium chloride receiving bath. The calcium ions in the receiving bath immediately react with the sodium alginate in the hydrogel, causing the droplets to quickly solidify and form microgels.

[0070] (5) Post-treatment and storage:

[0071] Wash the microgels with phosphate buffer to remove ion residues; freeze-dry the treated microgels and then store them after ultraviolet irradiation to maintain their magnetoresponsiveness and biocompatibility.

[0072] Example 3

[0073] This example provides a method for preparing chitosan microgels using a magnetic field, including the following steps:

[0074] (1) Material preparation:

[0075] Polymer material: 0.4 g of chitosan;

[0076] Magnetic nanoparticles: 2 g of SPIONS;

[0077] Receiving bath: Prepare a sodium hydroxide solution with a pH value of 10 - 12 as the receiving bath.

[0078] (2) Preparation of magnetoresponsive hydrogel solution:

[0079] Dissolve the chitosan powder and SPIONs mixture in 20 mL of acetic acid solution with a pH value of 4 - 5 to prepare a chitosan solution with a concentration of 2% (w / v). Stir with a magnetic stirrer at 800 rpm to ensure the uniform dispersion of SPIONs in the chitosan - acetic acid solution, forming a magnetoresponsive hydrogel solution.

[0080] (3) Setup and preparation of the device:

[0081] Select a cylindrical radial NS neodymium iron boron magnet with a radius of 3 cm. Place a petri dish containing sodium hydroxide solution with a pH value of 10 - 12 above the magnet as the receiving bath, and control the liquid level height not to exceed 0.2 cm. Then, erect a stable syringe and needle vertically above, adjust the vertical distance between the end of the needle and the magnet to 1 cm, and set the extrusion speed of the needle to 5 mL / min.

[0082] (4) Preparation of microgels:

[0083] Extrude the magnetoresponsive hydrogel solution in the syringe to form hydrogel droplets at the needle tip. Under the precise guidance of the magnetic field force, the hydrogel droplets quickly drop into the sodium hydroxide solution receiving bath. The sodium hydroxide in the receiving bath immediately undergoes a neutralization reaction with the acetic acid in the hydrogel, causing the chitosan solution to gelate and form microgels.

[0084] (5) Post - treatment and storage:

[0085] Wash the microgels multiple times with distilled water to remove unreacted sodium hydroxide and acetic acid; then place the microspheres on filter paper to absorb the surface moisture; freeze - dry the treated microgels and store them after ultraviolet irradiation to maintain their magnetoresponsiveness and biocompatibility.

[0086] Example 4

[0087] This example provides a method for preparing carboxymethyl cellulose (CMC) microgels using a magnetic field, including the following steps:

[0088] (1) Material preparation:

[0089] Polymer material: 1 g of CMC;

[0090] Magnetic nanoparticles: 2 g of SPIONS;

[0091] Receiving bath: Weigh 10 g of ferric chloride and dissolve it in 1 L of double - distilled water to prepare a 1% w / v ferric chloride solution as the receiving bath.

[0092] (2) Preparation of magnetoresponsive hydrogel solution:

[0093] Mix CMC with SPIONs, add 20 mL of double-distilled water to prepare a hydrogel solution of 5 wt% CMC and 10 wt% SPIONs, and stir with a magnetic stirrer at 800 rpm to ensure the uniform dispersion of SPIONs in the CMC solution, forming a magnetoresponsive hydrogel solution.

[0094] (3) Setup and preparation of the device:

[0095] Select a cylindrical radial NS neodymium iron boron magnet with a radius of 3 cm. Place a petri dish containing calcium chloride solution above the magnet as the receiving bath, control the liquid level height not to exceed 0.2 cm, then erect a stable syringe and needle vertically above, adjust the vertical distance between the end of the needle and the magnet to 1 cm, and set the extrusion speed of the needle to 5 mL / min.

[0096] (4) Preparation of microgels:

[0097] Extrude the magnetoresponsive hydrogel solution in the syringe to form hydrogel droplets at the needle tip. Under the precise guidance of the magnetic field force, the hydrogel droplets quickly drop into the ferric chloride receiving bath. The ferric ions in the receiving bath react with the carboxyl and hydroxyl groups in CMC to form a three-dimensional network structure, resulting in the gelation of the CMC solution and forming microgels.

[0098] (5) Post-treatment and storage:

[0099] Wash the microgels with phosphate buffer to remove ion residues; freeze-dry the treated microgels and then store them after ultraviolet irradiation to maintain their magnetoresponsiveness and biocompatibility.

[0100] Example 5

[0101] This example provides a method for preparing continuous microgels (microfiber hydrogels) using a magnetic field, including the following steps:

[0102] (1) Material preparation:

[0103] Polymer material: 0.2 g of sodium alginate;

[0104] Magnetic nanoparticles: 1 g of SPIONs;

[0105] Receiving bath: Weigh 100 g of calcium chloride and dissolve it in 1 L of double-distilled water to prepare a 10% w / v calcium chloride solution as the receiving bath.

[0106] (2) Preparation of magnetoresponsive hydrogel solution:

[0107] Mix sodium alginate with SPIONs, add 20 mL of double-distilled water to prepare a hydrogel solution of 1 wt% sodium alginate and 5 wt% SPIONs, and stir with a magnetic stirrer at 800 rpm to ensure the uniform dispersion of SPIONs in the sodium alginate solution, forming a magnetoresponsive hydrogel solution.

[0108] (3) Setup and preparation of the device:

[0109] Select a cylindrical radial NS neodymium iron boron magnet with a radius of 3 cm. Place a petri dish containing calcium chloride solution above the magnet as the receiving bath, control the liquid level height not to exceed 0.2 cm, then erect a stable syringe and needle vertically above, adjust the vertical distance between the end of the needle and the magnet to 1 cm, and set the extrusion speed of the needle to 20 mL / min.

[0110] (4) Preparation of microgels:

[0111] Extrude the magnetoresponsive hydrogel solution in the syringe so that it is continuously and rapidly extruded at the needle tip. Since the droplets contain SPIONs, they quickly enter the receiving area under the action of the magnetic field force and solidify to form fibrous continuous hydrogels.

[0112] (5) Post-treatment and storage:

[0113] Wash the microgels with phosphate buffer to remove ion residues; freeze-dry the treated microgels and then store them after ultraviolet irradiation to maintain their magnetoresponsiveness and biocompatibility.

[0114] The process of continuously preparing microgels (microfibers) using a magnetic field in this example is as Figure 8 shown.

[0115] Example 6

[0116] The difference between this example and Example 2 is that the vertical distance between the end of the needle and the magnet in step (3) is adjusted to 0.2, 1, 2, 3, 4, 5 cm respectively, and the remaining steps are the same as those in Example 2.

[0117] The relationship between the distance (H) between the needle and the magnet and the size of the microgels is as Figure 9 shown. It can be seen that the particle size of the microgels gradually increases with the increase of the distance. When the vertical distance is 0.2 cm, relatively small-sized microgels can be obtained. The reason for this phenomenon is that the magnetic field strength in the vertical direction weakens with the increase of the distance, thus reducing the magnetic attraction force on the microgel droplets. Therefore, the droplets need to increase their own volume and mass to overcome the solid-liquid interface surface tension between the needle and the droplets, and finally drop into the receiving bath to form microgels.

[0118] Example 7

[0119] The difference between this example and Example 5 is that the magnetic nanoparticles in step (1) are replaced with 0.2 g of SPIONs, that is, a hydrogel solution of 1 wt% sodium alginate and 1 wt% SPIONs is prepared, and the remaining steps are the same as those in Example 5.

[0120] Figure 10 It is a statistical chart of the relationship between the SPIONs concentration and the microgel size. It can be seen that under the same conditions, an increase in the SPIONs concentration can significantly produce smaller-sized microgels.

[0121] Figure 11 It is the biocompatibility detection of the microgels prepared in Example 2 and Example 7, and the scale bar is 200 μm. PI represents propidium iodide, and Calcein-AM represents calcein acetoxymethyl ester. The specific biocompatibility detection is to co-culture the prepared microgels with human umbilical vein endothelial cells, and then use a kit (Beyotime, Calcein / PI Cell Viability and Cytotoxicity Detection Kit C2015M) based on the double fluorescence staining method of Calcein-AM (calcein) and PI (propidium iodide) to detect the viability of animal cells, and the biocompatibility of the microgels is detected. The results show that the prepared microgels have good biocompatibility.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 2 is that the magnet in step (3) is removed, and only a culture dish containing calcium chloride solution is placed as the receiving bath. The remaining steps are the same as those in Example 2. As a result, the liquid drops float above the receiving bath after dropping, cannot enter the receiving bath, and cannot form uniform microgels.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 2 is that the neodymium iron boron magnet in step (3) is replaced with an iron magnet of the same size and shape with a residual magnetism of 0.2 T. The remaining steps are the same as those in Example 2. As a result, a hydrogel with a larger size rather than a microgel is prepared, and the preparation speed is low. Uniform-sized gels cannot be prepared. In addition, since it takes a long time for the liquid drops to drop, the distribution of SPIONs in the liquid drops is affected by gravity, and the distribution of magnetic substances in the formed microgels is extremely uneven.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 2 is that the extrusion speed of the set needle in step (3) is replaced from 5 mL / min to (the extrusion speed of the set needle is 1 mL / min), and the remaining steps are the same as those in Example 2. As a result, a hydrogel with a larger size rather than a microgel can be prepared, but the preparation speed is low, and a microgel with uniform size cannot be prepared. Moreover, since it takes a long time for the liquid droplets to drip, the distribution of SPIONs in the liquid droplets is affected by gravity, and the distribution of magnetic substances in the formed microgel is extremely uneven.

[0128] Comparative Example 4

[0129] The difference between this comparative example and Example 2 is that the 30G needle in step (3) is replaced by a 12G needle, and the remaining steps are the same as those in Example 2. As a result, a hydrogel with a millimeter-sized size rather than a microgel can be prepared. Before the liquid droplets are completely formed, they directly drip under the action of the magnetic field, and the distribution of magnetic substances in the formed microgel is extremely uneven.

[0130] Comparative Example 5

[0131] The difference between this comparative example and Example 2 is that the 10% w / v calcium chloride solution in step (3) is replaced by a 0.2% w / v calcium chloride solution, and the remaining steps are the same as those in Example 2. As a result, a microgel with uniform size cannot be prepared.

[0132] It should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing microgel based on a magnetic field, characterized in that: include, The polymer material and the magnetic nanoparticles are uniformly mixed to prepare a magnetically responsive hydrogel solution; Prepare a magnet, place a receiving bath on top of the magnet, and then set up a stable needle tube and needle vertically above to build a microgel preparation device; The magnetically responsive hydrogel solution is placed in a syringe, and the magnetically responsive hydrogel solution in the syringe is squeezed out to form hydrogel droplets at the needle tip. The hydrogel droplets quickly drip into the receiving bath under the action of the magnetic field, thereby obtaining microgels.

2. The preparation method according to claim 1, characterized in that: The polymer material is at least one of sodium alginate, chitosan, carboxymethyl cellulose or other hydrogels cross-linked with the receiving bath.

3. The preparation method according to claim 1, characterized in that: The magnetic nanoparticles are nanoparticles with magnetism or superparamagnetism.

4. The preparation method according to claim 1, characterized in that: The concentration of superparamagnetic iron oxide nanoparticles in the magnetic responsive hydrogel solution is 0.01 to 99.9 wt %.

5. The preparation method according to claim 1, characterized in that: The receiving bath is a solution that matches the polymer material and can trigger a rapid cross-linking reaction with the polymer material.

6. The preparation method according to claim 1, characterized in that: The magnet is a magnet or an electromagnet with a residual magnetism greater than 1.1T.

7. The preparation method according to claim 1, characterized in that: The needle tube and the needle are mounted vertically upward to stabilize the needle, wherein the vertical distance between the end of the needle and the magnet is 0.2 to 5 cm.

8. The microgel obtained by the preparation method according to any one of claims 1 to 7.

9. The microgel according to claim 8, characterized in that: The shape and size of the microgel are controllable.

10. Use of the microgel prepared by the preparation method according to any one of claims 1 to 7.

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