A method for preparing gelatin polyelectrolyte brushes by photoinitiated emulsion polymerization

Abstract

The present invention provides a method for preparing a gelatin polyelectrolyte brush by a photo-initiated emulsion polymerization method. After the methacrylated gelatin nanoparticles surface-modified by methacrylic anhydride are grafted with a photoinitiator HMEM on the surface, they are mixed with polyelectrolyte monomers and subjected to ultraviolet light irradiation to initiate a polymerization reaction. Under the action of the photoinitiator HMEM, the polyelectrolyte monomers are grafted on the surface of the gelatin sphere core to form a slender molecular chain, and finally a "brush"-like structure is formed to obtain a gelatin spherical polyelectrolyte brush. The gelatin spherical polyelectrolyte brush prepared by the present invention has a regular morphology and uniform size, and the brush layer thickness of the gelatin spherical polyelectrolyte brush can be adjusted by changing the monomer amount, reaction time, ionic strength and pH value, and has broad application prospects in the field of biomedicine.

Description

Technical Field

[0001] The invention relates to the field of functional polymer material preparation, and in particular to a method for preparing a gelatin polyelectrolyte brush by light-initiated emulsion polymerization, and a gelatin polyelectrolyte brush prepared by the method. Background Art

[0002] Spherical Polyelectrolyte Brush (SPB) refers to a macromolecular assembly structure formed by polyelectrolyte chains connected to the surface of nano-spherical particles with a certain grafting density. Traditional materials for synthesizing SPB cores (such as polystyrene, polybutadiene, etc.) have potential problems in biodegradation, which limits the application of SPB in the biomedical field.

[0003] As a natural polymer material, gelatin has good biocompatibility, biodegradability, non-immunogenicity and blood compatibility. With gelatin as the core of nano-spherical polyelectrolyte brushes, combined with the unique properties of nano-spherical polyelectrolyte brushes such as excellent stability, biolubricity and wettability, it can be widely used in biomedical fields such as tissue engineering, drug delivery systems, and immunodiagnosis. Photo-initiated emulsion polymerization is a polymerization reaction initiated by free radicals generated by photoinitiators after being irradiated with ultraviolet light. It has the advantages of fast reaction rate, high selectivity, controllable structure, no need to use toxic catalysts, and mild reaction conditions.

[0004] Therefore, it is of great significance to combine photoinitiation technology to provide a method for preparing polyelectrolyte brushes with milder preparation conditions, higher efficiency and good biocompatibility. Summary of the invention

[0005] The invention provides a method for preparing a gelatin spherical polyelectrolyte brush by a light-initiated emulsion polymerization method, which can prepare a gelatin spherical polyelectrolyte brush with uniform particle size and good biocompatibility.

[0006] To achieve the above object, the technical scheme of the present invention is as follows: A method for preparing a gelatin polyelectrolyte brush by a photoinitiated emulsion polymerization method, comprising mixing methacrylated gelatin nanoparticles with a surface grafted photoinitiator with a polyelectrolyte monomer, adjusting the pH value of the reaction system, and initiating a polymerization reaction under ultraviolet light in an oxygen-free environment to obtain a gelatin spherical polyelectrolyte brush; wherein the polyelectrolyte monomer is selected from any one of anionic polyelectrolyte monomers, cationic polyelectrolyte monomers, zwitterionic polyelectrolyte monomers, or neutral polyelectrolyte monomers;

[0007] When the polyelectrolyte monomer is an anionic polyelectrolyte monomer or a cationic polyelectrolyte monomer, the pH of the reaction system is adjusted until the methacrylated gelatin nanoparticles with the surface grafted photoinitiator have opposite charges to the polyelectrolyte monomer; when the polyelectrolyte monomer is a zwitterionic polyelectrolyte monomer or a neutral polyelectrolyte monomer, the pH of the reaction system is adjusted to the isoelectric point of the methacrylated gelatin nanoparticles with the surface grafted photoinitiator.

[0008] When the above reaction system is undergoing polymerization reaction, the polyelectrolyte monomer will be grafted on the surface of the gelatin spherical core under the action of the photoinitiator to form a slender molecular chain, and finally form a "brush"-like structure to obtain the gelatin spherical polyelectrolyte brush.

[0009] It is further preferred that the anionic polyelectrolyte monomers include acrylic acid, sodium p-styrene sulfonate, and 2-acrylamido-2-methylpropane sulfonic acid (AMPS).

[0010] In the present invention, it is further preferred that the cationic polyelectrolyte monomers include methacryloyloxyethyltrimethylammonium chloride, 2-aminoethyl ester hydrochloride, and acryloyloxyethyltrimethylammonium chloride.

[0011] The present invention is further preferred that the zwitterionic polyelectrolyte monomers include [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide, 3-[[2-(methyl acryloyloxy)yl]dimethylamino] acid salt, and 2-methacryloyloxyethyl phosphorylcholine.

[0012] In the present invention, the neutral polyelectrolyte monomers include methacrylate, styrene, and N-isopropylacrylamide.

[0013] The present invention is further preferably that the photoinitiator is 2-[p-(2-hydroxy-2-methylpropiophenone)]-ethylene glycol-acrylate (HMEM), and the structural formula of the photoinitiator HMEM is as follows:

[0014]

[0015] The present invention is further preferably characterized in that the mass ratio of the polyelectrolyte monomer to the methacrylated gelatin nanoparticles with the surface grafted photoinitiator is (1-15):1.

[0016] It is further preferred that the polymerization reaction time is 2 to 3 hours.

[0017] It is further preferred in the present invention that the prepared gelatin spherical polyelectrolyte brush has a chain length of 10-400 nm.

[0018] The present invention is further preferably that the method for preparing the gelatin spherical polyelectrolyte brush comprises the following steps:

[0019] S1: Using gelatin as raw material, the desolvation method is adopted, and a cross-linking agent is added to allow gelatin to self-assemble to form gelatin nanoparticles;

[0020] S2: using methacrylic anhydride to perform surface modification on the prepared gelatin nanoparticles to prepare methacrylated gelatin nanoparticles;

[0021] S3: Grafting the photoinitiator HMEM on the surface of the methacrylated gelatin nanoparticles;

[0022] S4: The methacrylated gelatin nanoparticles grafted with a photoinitiator are mixed with a polyelectrolyte monomer, the pH of the reaction system is adjusted, and then a polymerization reaction is carried out under ultraviolet light.

[0023] The present invention is further preferably that in step S4, NaOH or HCl solution is used to adjust the pH of the reaction system.

[0024] The present invention is further preferably that in step S1, the preparation of the gelatin nanoparticles comprises the following steps:

[0025] (1) Mix gelatin and deionized water, stir to dissolve, add concentrated hydrochloric acid, and adjust the pH value of the system to 1-3;

[0026] (2) adding excess acetone to the above reaction system until the turbidity of the reaction system increases significantly, so that the long chains of gelatin molecules curl up to form self-assembled nanoparticles;

[0027] (3) adding a cross-linking agent glutaraldehyde solution to cross-link and solidify the gelatin particles;

[0028] (4) adding guanidine hydrochloride solution to neutralize the residual glutaraldehyde in the reaction system, terminate the cross-linking reaction, and centrifuge, purify, and freeze-dry the solution to obtain the self-assembled gelatin nanoparticles.

[0029] The present invention is further preferably that in step S2, the preparation of the methacrylated gelatin nanoparticles comprises the following steps:

[0030] (1) mixing and stirring the gelatin nanoparticles and a carbonate-sodium bicarbonate buffer (CB buffer) to dissolve, and adjusting the pH to 8-10;

[0031] (2) adding a certain amount of methacrylic anhydride and reacting at 50-55° C. in the dark;

[0032] (3) After the reaction is completed in a dark environment, the product is dialyzed in hot water for purification, and the molecular weight cut-off of the dialysis bag is 8-14 KDa;

[0033] (4) freeze-drying the purified solution to obtain the desired methacrylated gelatin nanoparticles.

[0034] The present invention is further preferably that in step S3, the methacrylated gelatin nanoparticles modified with methacrylic anhydride and the photoinitiator HMEM are mixed under a nitrogen atmosphere and reacted at 70-90° C. for 2-3 hours to obtain the methacrylated gelatin nanoparticles with the surface grafted with the photoinitiator.

[0035] The present invention is further preferably provided that, in step S4, after the polyelectrolyte monomer is dissolved in deionized water, it is added into a reaction device together with the methacrylated gelatin nanoparticles with the surface grafted photoinitiator, the pH value of the solution is adjusted, nitrogen is pumped in, and then the polymerization reaction is initiated by ultraviolet light irradiation under stirring. After the reaction has lasted for 2-3 hours, the irradiation is stopped, and the reaction product is dialyzed in deionized water using a dialysis bag to obtain the gelatin spherical polyelectrolyte brush.

[0036] The present invention is further preferably that the method for preparing the gelatin spherical polyelectrolyte brush comprises the following steps:

[0037] S1: Add gelatin and deionized water into a three-necked flask, stir and dissolve at 35-50°C, then drop concentrated hydrochloric acid to adjust the pH value of the system to 1-3;

[0038] S2: Adding a large amount of acetone causes the long chains of gelatin molecules to curl up to form self-assembled nanoparticles;

[0039] S3: adding cross-linking agent glutaraldehyde to cross-link and solidify the gelatin particles;

[0040] S4: adding guanidine hydrochloride solution to neutralize the residual glutaraldehyde in the system, terminating the cross-linking reaction, and centrifuging and purifying the product to obtain gelatin nanoparticles;

[0041] S5: Mix gelatin nanoparticles, CB buffer and additional deionized water in a flask to make the gelatin nanoparticle concentration reach 1-3wt%, and stir well at 45-55°C;

[0042] S5: adding methacrylic anhydride (MA) to the above-mentioned mixed system, reacting for 1.0-2.0 hours under magnetic stirring at 500-700 rpm, and dialysis and purification with deionized water to obtain methacrylic anhydride-modified gelatin nanoparticles after the reaction is completed;

[0043] S6: mixing the prepared methacrylated gelatin nanoparticles (Gel-MA) and the photoinitiator HMEM in a flask under a nitrogen atmosphere, and reacting at 75-85° C. for 2-3 h to obtain Gel-HMEM;

[0044] S7: After dissolving the polyelectrolyte monomer in deionized water, add it into the flask together with Gel-HMEM, and adjust the pH value of the solution with NaOH or HCl;

[0045] S8: After nitrogen is pumped out, the mixture is reacted for 2-3 hours under ultraviolet light irradiation at 750-850 rpm magnetic stirring, and then dialyzed in deionized water using a dialysis bag to obtain a gelatin spherical polyelectrolyte brush.

[0046] The present invention also provides a gelatin spherical polyelectrolyte brush prepared according to any one of the above methods for preparing a gelatin polyelectrolyte brush.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The present invention adopts a photo-initiated emulsion polymerization method, which belongs to the "surface grafting" method. The surface grafting density is relatively high, and the grafting density can be regulated by the amount of photoinitiator added. The brush layer thickness of the gelatin spherical polyelectrolyte brush can be adjusted by changing the monomer amount, reaction time, ionic strength and pH value.

[0049] (2) The present invention successfully synthesized a new type of gelatin spherical polyelectrolyte brush through photoinitiated polymerization. The material has a controllable polyelectrolyte chain length, and no toxic substances that are difficult to remove are introduced during the preparation process. It has good biocompatibility, which makes it have broad application prospects in biomedical applications.

[0050] (3) In the preparation process of the present invention, methacrylic anhydride is used as a surface modification agent, 2-[p-(2-hydroxy-2-methylpropiophenone)]-ethylene glycol-acrylate (HMEM) is used as a photoinitiator, and a photo-initiated emulsion polymerization method is adopted to prepare gelatin spherical polyelectrolyte brushes. The method has good repeatability, mild experimental conditions, can be carried out at room temperature, and requires a shorter time. The product has a regular morphology and uniform particle size. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The figure is a flow chart of the preparation of the gelatin spherical polyelectrolyte brush described in the present invention.

[0052] Figure 2 This is the SEM electron microscope image of gelatin nanoparticles (Gel-NPs) prepared in Example 1.

[0053] Figure 3 This is the particle size distribution diagram of the gelatin spherical polyelectrolyte brush prepared in Example 1 and the gelatin nanoparticles before grafting monomers.

[0054] Figure 4The infrared spectra of the gelatin spherical polyelectrolyte brush Gel-PAMPS, AMPS monomer, Gel-HMEM after Gel-MA grafted with photoinitiator, MA-modified gelatin nanoparticles Gel-MA, and cross-linked gelatin nanoparticles Gel-NPs prepared in Example 1. DETAILED DESCRIPTION

[0055] The present invention is further described below by way of examples. The following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0056] All raw materials in the present invention can be directly purchased. In the embodiments of the present invention, dynamic light scattering, SEM electron microscope and infrared spectrum are used to characterize the products in the preparation process.

[0057] The chain length of the spherical polyelectrolyte brush in the present invention = (D (Gel-PAMPS) -D (Gel-NPs) ) / 2.

[0058] Example 1

[0059] like Figure 1 As shown, in this embodiment, gelatin nanoparticles, methacrylated gelatin nanoparticles, and methacrylated gelatin nanoparticles with surface grafted photoinitiators are prepared in sequence using gelatin as a raw material, and finally gelatin spherical polyelectrolyte brushes are prepared by photoinitiated emulsion polymerization.

[0060] The preparation of the gelatin spherical polyelectrolyte brush specifically includes the following process: weighing 5g of gelatin and 60mL of deionized water, putting them into a three-necked flask and stirring to dissolve them at 40°C, dropping concentrated hydrochloric acid, adjusting the pH value of the system to 1-3, and then adding excess acetone to greatly increase the turbidity of the reaction system; then adding 600μL of glutaraldehyde solution and cross-linking reaction overnight, adding 100mL of 100mM guanidine hydrochloride aqueous solution, stirring the reaction for 1-2h, centrifuging and purifying, and then freeze-drying to obtain gelatin nanoparticles (Gel-NPs), and using SEM electron microscopy to characterize the morphology of the gelatin nanoparticles, such as Figure 2 As shown;

[0061] 1 g of Gel-NPs was weighed and dissolved in 100 mL of 1 M sodium carbonate-sodium bicarbonate buffer, and the pH was adjusted to 9, and then 1-1.5 mL of methacrylic anhydride was added. After reacting at 50-55° C. in the dark for 1 hour, the product was dialyzed and purified to obtain Gel-MA; 100 mL of Gel-MA was weighed and added to a three-necked flask, and after nitrogen was pumped in 5 times, it was placed in an oil bath and stirred at 80° C., 200 mg of HMEM was injected into the flask with a syringe, and after reacting for 2-3 hours, methacrylated gelatin nanoparticles (Gel-HMEM) with a surface grafted photoinitiator were obtained;

[0062] Weigh 100 mg of AMPS and dissolve it in deionized water, then add it and 20 mg of Gel-HMEM into a flask and mix them. Use NaOH to adjust the pH of the solution to alkaline so that Gel-HMEM and the polyelectrolyte monomer carry opposite charges. Pump nitrogen for 5 times, and then irradiate with ultraviolet light under 800 rpm magnetic stirring to initiate photopolymerization. After reacting for 2-3 hours, dialysis the product with a dialysis bag for purification, and freeze-dry the purified solution to obtain the desired spherical polyelectrolyte brush Gel-PAMPS. In the above preparation process, a dynamic light scattering instrument is used to detect the particle size distribution of the reaction product, and infrared characterization is performed on the reaction products of each process. The particle size distribution diagram and infrared spectrum diagram results are shown in FIG. Figure 3 and Figure 4 The chain length of the obtained spherical polyelectrolyte brush is 200 nm.

[0063] Example 2

[0064] The difference from Example 1 is that the polyelectrolyte monomer selected is acrylic acid (AA). The process of photoinitiated emulsion polymerization is as follows: 20 mg of Gel-HMEM and 100 mg of AA are weighed and mixed, and the pH of the solution is adjusted to alkaline after mixing, and nitrogen is pumped and filled for 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours, and the product is dialyzed and purified with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PAA, and the chain length of the obtained spherical polyelectrolyte brush is 190 nm.

[0065] Example 3

[0066] The difference from Example 1 is that the polyelectrolyte monomer selected is sodium p-styrene sulfonate (SS). The process of light-initiated emulsion polymerization is as follows: 20 mg of Gel-HMEM and 100 mg of SS are weighed and mixed, and the pH of the solution is adjusted to alkaline after mixing, and nitrogen is pumped and filled for 5 times, and then the reaction is irradiated with ultraviolet light for 2.5 hours, and the product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PSS, and the chain length of the obtained spherical polyelectrolyte brush is 195 nm.

[0067] Example 4

[0068] The difference from Example 1 is that the selected polyelectrolyte monomer is methacryloyloxyethyl trimethyl ammonium chloride (METAC), and the pH of the solution is adjusted to acidic before the polymerization reaction, so that Gel-HMEM and the polyelectrolyte monomer have opposite charges. The process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg METAC are weighed, the pH of the solution is adjusted to acidic after mixing, nitrogen is pumped and filled 5 times, and ultraviolet light is irradiated for 2.5 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PMETAC. The chain length of the obtained spherical polyelectrolyte brush is 150 nm.

[0069] Example 5

[0070] The difference from Example 4 is that the selected polyelectrolyte monomer is 2-aminoethyl hydrochloride (AMA), and the process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg AMA are weighed, the pH of the solution is adjusted to acidic after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PAMA. The chain length of the obtained spherical polyelectrolyte brush is 144 nm.

[0071] Example 6

[0072] The difference from Example 4 is that the selected polyelectrolyte monomer is acryloyloxyethyltrimethylammonium chloride (DMC), and the process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg DMC are weighed, the pH of the solution is adjusted to acidic after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PDMC. The chain length of the obtained spherical polyelectrolyte brush is 154 nm.

[0073] Example 7

[0074] The difference from Example 1 is that the selected polyelectrolyte monomer is [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide (SBMA), and the pH of the solution is adjusted to 4-5 before the polymerization reaction, to the isoelectric point of Gel-HMEM, and the process of light-initiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg SBMA are weighed, the pH of the solution is adjusted to 4-5 after mixing, nitrogen is pumped and filled 5 times, and then the reaction is irradiated with ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PSBMA, and the chain length of the obtained spherical polyelectrolyte brush is 250 nm.

[0075] Example 8

[0076] The difference from Example 7 is that the selected polyelectrolyte monomer is 3-[[2-(methylenoyloxy)]dimethylamino]indole (CBMA), and the process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg CBMA are weighed, the pH of the solution is adjusted to 4-5 after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PCBMA. The chain length of the obtained spherical polyelectrolyte brush is 252 nm.

[0077] Example 9

[0078] The difference from Example 7 is that the selected polyelectrolyte monomer is 2-methacryloyloxyethyl phosphorylcholine (MPC), and the process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg MPC are weighed, the pH of the solution is adjusted to 4-5 after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PMPC. The chain length of the obtained spherical polyelectrolyte brush is 253 nm.

[0079] Example 10

[0080] The difference from Example 1 is that the selected polyelectrolyte monomer is methyl methacrylate (MMA), and the pH of the solution is adjusted to 4-5 before the reaction, to the isoelectric point of Gel-HMEM. The process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg MMA are weighed, and the pH of the solution is adjusted to 4-5 after mixing. After nitrogen is pumped and filled for 5 times, ultraviolet light is used for reaction for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PMMA. The chain length of the obtained spherical polyelectrolyte brush is 200 nm.

[0081] Embodiment 11

[0082] The difference from Example 10 is that the selected polyelectrolyte monomer is styrene (PS), and the process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg PS are weighed, the pH of the solution is adjusted to 4-5 after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PPS. The chain length of the obtained spherical polyelectrolyte brush is 195 nm.

[0083] Example 12

[0084] The difference from Example 10 is that the selected polyelectrolyte monomer is N-isopropylacrylamide (NIPAM), and the process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 100 mg NIPAM are weighed, the pH of the solution is adjusted to 4-5 after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PNIPAM. The chain length of the obtained spherical polyelectrolyte brush is 194 nm.

[0085] Example 13

[0086] The difference from Example 1 is that the pH value of the solution is not adjusted before the photo-initiated emulsion polymerization reaction, and the pH value of the solution remains acidic after mixing. After nitrogen is pumped and filled for 5 times, the reaction is irradiated with ultraviolet light for 2-3 hours, and the reaction precipitates, and no spherical polyelectrolyte brush can be obtained.

[0087] Embodiment 14

[0088] The difference from Example 1 is that the amount of AMPS monomer added is different. The process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 10 mg AMPS are weighed, the pH of the solution is adjusted to alkaline after mixing, nitrogen is pumped and filled 5 times, and then the reaction is irradiated with ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PAMPS. The chain length of the obtained spherical polyelectrolyte brush is 10 nm.

[0089] Embodiment 15

[0090] The difference from Example 1 is that the amount of AMPS monomer added is different. The process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 200 mg AMPS are weighed, the pH of the solution is adjusted to alkaline after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PAMPS. The chain length of the obtained spherical polyelectrolyte brush is 400 nm.

[0091] Example 16

[0092] The difference from Example 1 is that the amount of AMPS monomer added is different. The process of photoinitiated emulsion polymerization is as follows: 20 mg Gel-HMEM and 300 mg AMPS are weighed, the pH of the solution is adjusted to alkaline after mixing, nitrogen is pumped and filled 5 times, and then the reaction is carried out under ultraviolet light for 2-3 hours. The product is dialyzed and purified for three days with a dialysis bag, and the purified solution is freeze-dried to obtain Gel-PAMPS. The chain length of the obtained spherical polyelectrolyte brush is 380 nm.

[0093] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing gelatin polyelectrolyte brushes by photoinitiated emulsion polymerization, characterized in that: After the methacrylated gelatin nanoparticles with a surface grafted photoinitiator are mixed with a polyelectrolyte monomer, the pH value of the reaction system is adjusted, and then a polymerization reaction is initiated by ultraviolet light in an oxygen-free environment to obtain a gelatin spherical polyelectrolyte brush; the specific steps include: S1: Using gelatin as raw material, the desolvation method is adopted, and a cross-linking agent is added to allow gelatin to self-assemble to form gelatin nanoparticles; S2: using methacrylic anhydride to perform surface modification on the prepared gelatin nanoparticles to prepare methacrylated gelatin nanoparticles; S3: mixing the methacrylated gelatin nanoparticles modified with methacrylic anhydride and the photoinitiator HMEM under a nitrogen atmosphere, and reacting them at 70-90° C. for 2-3 h to obtain the methacrylated gelatin nanoparticles with the photoinitiator grafted on the surface; S4: mixing the methacrylated gelatin nanoparticles with a surface-grafted photoinitiator with a polyelectrolyte monomer, adjusting the pH of the reaction system, and then performing a polymerization reaction under ultraviolet light to obtain the gelatin spherical polyelectrolyte brush; Wherein, the polyelectrolyte monomer is selected from any one of anionic polyelectrolyte monomers, cationic polyelectrolyte monomers or zwitterionic polyelectrolyte monomers; the anionic polyelectrolyte monomer includes acrylic acid, sodium p-styrene sulfonate or 2-acrylamido-2-methylpropane sulfonic acid; the cationic polyelectrolyte monomer includes methacryloyloxyethyl trimethylammonium chloride or acryloyloxyethyl trimethylammonium chloride; the zwitterionic polyelectrolyte monomer includes [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide, 3-[[2-(methyl acryloyloxy)]dimethylamino] inner acid salt or 2-methacryloyloxyethyl phosphorylcholine; When the polyelectrolyte monomer is an anionic polyelectrolyte monomer or a cationic polyelectrolyte monomer, the pH of the reaction system is adjusted until the methacrylated gelatin nanoparticles with the surface grafted photoinitiator have opposite charges to the polyelectrolyte monomer; when the polyelectrolyte monomer is a zwitterionic polyelectrolyte monomer, the pH of the reaction system is adjusted to the isoelectric point of the methacrylated gelatin nanoparticles with the surface grafted photoinitiator.

2. The method for preparing gelatin polyelectrolyte brushes by photo-initiated emulsion polymerization according to claim 1, characterized in that: The mass ratio of the polyelectrolyte monomer to the methacrylated gelatin nanoparticles with a surface-grafted photoinitiator is (1-15):

1.

3. The method for preparing gelatin polyelectrolyte brushes by photo-initiated emulsion polymerization according to claim 1, characterized in that: The reaction time of the polymerization reaction is 2-3h.

4. The method for preparing gelatin polyelectrolyte brushes by photo-initiated emulsion polymerization according to claim 1, characterized in that: The prepared gelatin spherical polyelectrolyte brush has a chain length of 10-400 nm.

5. The method for preparing gelatin polyelectrolyte brushes by photo-initiated emulsion polymerization according to claim 1, characterized in that: In step S2, the preparation of the methacrylated gelatin nanoparticles comprises the following steps: (1) mixing and stirring the gelatin nanoparticles and the carbonic acid-sodium bicarbonate buffer to dissolve, and adjusting the pH to 8-10; (2) Add a certain amount of methacrylic anhydride and carry out the reaction at 50-55°C in the dark; (3) After the reaction is completed in a dark environment, the product is dialyzed in hot water for purification, and the molecular weight cut-off of the dialysis bag is 8-14 KDa; (4) freeze-drying the purified solution to obtain the desired methacrylated gelatin nanoparticles.

6. A gelatin spherical polyelectrolyte brush prepared according to the method for preparing a gelatin polyelectrolyte brush according to any one of claims 1 to 5.

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