A high-strength, self-healing amidourea zwitterionic hydrogel and preparation method thereof

Abstract

The present invention discloses a kind of amido urea zwitterion hydrogel with high strength and self-healing and its preparation method, first by (methyl) acrylate isocyanoethyl and dimethylamino hydrazide reaction obtain the vinyl intermediate containing tertiary amino group, further with β-propiolactone or 1,3-propane sultone reaction obtain (methyl) acrylic acid amido urea zwitterion betaine monomer, finally by free radical initiation (light initiation or heat initiation) polymerization obtain amido urea zwitterion hydrogel. The hydrogel can be gelled without crosslinking agent, and has high strength, self-healing and excellent antifouling characteristics. After the gel is prepared into lyophilized powder by extrusion lyophilization, it can be stored for a long time, and after redissolving in deionized water or phosphate buffer solution, it can immediately form a gel with excellent injectability, and it has huge application prospects in the biological fields such as cryopreservation of cells, drug packaging, and postoperative anti-adhesion.

Description

Technical Field

[0001] The invention belongs to the field of hydrogel materials, and more specifically, relates to a high-strength, self-healing amidourea zwitterionic hydrogel and a preparation method thereof. Background Art

[0002] Hydrogels are a type of polymer material with a hydrophilic three-dimensional network structure formed by physical or chemical crosslinking. Since they are very similar to organisms and are mainly composed of water, hydrogels are expected to be used in various biomedical fields. However, the adhesion of nonspecific proteins, cells, bacteria, etc. has brought serious obstacles to the sustainable development of hydrogels in the biomedical field. Zwitterionic hydrogels contain strongly charged groups and high dipole moments on their molecular chains. Zwitterionic groups can firmly bind to water molecules through electrostatically induced hydration, thereby forming a dense hydration layer on the surface of the material. This hydration layer can effectively inhibit the adsorption of nonspecific proteins, cells, bacteria, etc., and exhibits excellent biocompatibility and antifouling properties. It can prevent biological contamination and effectively inhibit immunogenic reactions in biomedical processes. However, most of the existing zwitterionic polymer hydrogels need to be crosslinked using chemical crosslinkers, and their mechanical properties are usually poor, which limits the application range of zwitterionic hydrogels. The present invention generates an intermediate having amidourea by reacting isocyanoethyl (methyl)acrylate and dimethylaminohydrazide, and further generates an amidourea zwitterionic monomer by ring-opening reaction with a zwitterionic monomer, and obtains an amidourea zwitterionic hydrogel by double-bond free radical polymerization. Not only does it solve the problem of poor mechanical properties of zwitterionic hydrogel, but the zwitterionic hydrogel also has excellent self-healing properties. After being prepared into a lyophilized powder by extrusion lyophilization, it can be stored for a long time, and can immediately form a gel with excellent injectability after being redissolved in deionized water or phosphate buffer solution. It shows great application prospects in the biomedical field. Summary of the invention

[0003] The object of the present invention is to provide an amidourea zwitterionic hydrogel with high strength and self-healing properties and a method for preparing the same. The invention introduces amidourea groups by reacting isocyanoethyl (meth)acrylate and dimethylaminohydrazide, thereby introducing multiple hydrogen bonds, and performing physical crosslinking through the action of multiple hydrogen bonds between polymer molecules, thereby improving the mechanical strength of the hydrogel and solving the problem that the mechanical properties of traditional zwitterionic hydrogels are usually weak. Moreover, since the hydrogel is physically crosslinked, the hydrogel also has good self-healing properties. At the same time, after the gel that has reached swelling equilibrium in water is extruded and freeze-dried through an extrusion net with a diameter of 10 to 500 μm, the freeze-dried powder can be immediately gelled after being re-dissolved in deionized water or a phosphate buffer solution. The re-dissolved gel has better self-healing properties and injectability, and it shows great application prospects in the fields of postoperative anti-adhesion and cell cryopreservation.

[0004] The technical solution of the present invention is as follows:

[0005] A high-strength, self-healing amidourea zwitterionic hydrogel and a preparation method thereof, characterized in that a certain mass of amidourea zwitterionic monomer is weighed at a molar concentration, dissolved in water or a phosphate buffer solution, and prepared into a solution with a molar concentration of 1 to 6 mol / L, and then a photoinitiator or thermal initiator is added at a molar ratio of 0.1 to 2% relative to the monomer, and then injected into a closed mold, and the monomer polymerization is initiated by photoinitiation or thermal initiation. After a period of reaction time, the mold is opened to take out the hydrogel, and the unreacted monomer is removed by soaking in water for at least 1 day to obtain the amidourea zwitterionic hydrogel. The molecular structure of the polymer is shown below:

[0006]

[0007] Among them, R 1 CH 3 or H; R 2 for m is the degree of polymerization of the zwitterionic monomer, and its value is 20-6000; n is an integer of 1-5.

[0008] The above-mentioned 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) or 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959) is selected as an ultraviolet light initiator to carry out polymerization reaction under an external lamp, and the reaction time is 10 to 180 minutes;

[0009] The above-mentioned ammonium persulfate is selected as the thermal initiator, the polymerization reaction temperature is 60-80°C, and the polymerization time is 12-24 hours;

[0010] The synthesis method of the amidourea zwitterionic monomer is as follows:

[0011] Step 1: react isocyanoethyl (meth)acrylate and dimethylaminohydrazide to obtain a vinyl intermediate containing a tertiary amine group and an amidourea group. That is, weigh isocyanoethyl (meth)acrylate and dimethylaminohydrazide in a monomer molar ratio of 1: (1-5) and dissolve them in anhydrous tetrahydrofuran or anhydrous acetone, add isocyanoethyl (meth)acrylate dropwise to the tetrahydrofuran or acetone solution of dimethylaminohydrazide under low temperature stirring, and react at 5-10°C for 12 hours under nitrogen protection. After centrifugation, a white precipitate is obtained, which is further washed with ether and dried to obtain a vinyl intermediate containing a tertiary amine and an amidourea group. Its structure is shown in the following chemical formula:

[0012]

[0013] Where R is CH 3Or H; n is an integer from 1 to 5.

[0014] The chemical structure of isocyanoethyl (meth)acrylate is shown below:

[0015]

[0016] Where R is CH 3 or H;

[0017] The chemical structure of dimethylaminohydrazide is shown below:

[0018]

[0019] Wherein n is an integer from 1 to 5.

[0020] Step 2: The vinyl intermediate containing tertiary amine group and amidourea group obtained in step 1 is reacted with β-propiolactone or 1,3-propane sultone to obtain amidourea zwitterionic monomer. That is, the intermediate obtained in step 1 is weighed in a molar ratio of 1: (1-2) and dissolved in 25 ml of anhydrous tetrahydrofuran or anhydrous acetone, and heated to dissolve at 45-60°C. Then 1-2 equivalents of β-propiolactone or 1,3-propane sultone are weighed and added dropwise to the intermediate solution, stirring while adding dropwise, and after the addition is completed, it is rinsed with 200 microliters of anhydrous tetrahydrofuran or anhydrous acetone, stirred and reacted at 45-60°C for 12 hours, and a white precipitate is obtained after centrifugation, and further washed with ether and dried to obtain an amidourea zwitterionic monomer. Its chemical structure is shown below:

[0021]

[0022] Among them, R 1 CH 3 or H; R 2 for n is an integer of 1-5.

[0023] The above microgel preparation method is as follows:

[0024] The hydrogel prepared as above is extruded into microgel through an extrusion net with a certain diameter (10 to 500 μm), and then dried by a vacuum freeze dryer to obtain a hydrogel freeze-dried powder that is easy to store. The freeze-dried powder is dissolved in deionized water or phosphate buffer solution at a certain mass ratio (1 to 50%) to obtain a hydrogel with excellent self-healing properties and injectable properties.

[0025] The present invention obtains a vinyl intermediate containing a tertiary amine group and an amidourea group by reacting (methyl) acrylate isocyanoethyl with dimethylaminohydrazide, and further reacts with β-propiolactone or 1,3-propane sultone to obtain a zwitterionic monomer of amidourea. Then, a zwitterionic hydrogel with high strength and self-healing properties is prepared by free radical polymerization. In addition, the hydrogel is extruded and freeze-dried through an extrusion net with a certain diameter (10 to 500 μm) to obtain a microgel powder, which is not only easy to store, but also can immediately form a completely physically cross-linked zwitterionic hydrogel after being redissolved in deionized water or a phosphate buffer solution, and the hydrogel has more excellent self-healing and injectability.

[0026] The advantages of the present invention are: (1) the raw materials are readily available, and the synthesis and preparation methods are simple; (2) the prepared zwitterionic hydrogel can be gelled without adding any crosslinking agent; (3) the prepared zwitterionic hydrogel has high strength and self-healing properties; (4) the prepared hydrogel can be further prepared into microgel powder, which is not only easy to store, but also has better self-healing properties and injectability after being re-dissolved into gel in water or phosphate buffer solution at a certain mass ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the nuclear magnetic spectrum of the intermediate (ASC) prepared by the present invention, which has no methyl group on the double bond and contains a tertiary amino group and an amidourea group.

[0028] Figure 2 The present invention discloses a nuclear magnetic resonance spectrum of the acrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBAA) prepared by the present invention.

[0029] Figure 3 The figure is the nuclear magnetic spectrum of the intermediate (ASC-MA) having a double bond with a methyl group and containing a tertiary amino group and an amidourea group prepared by the present invention.

[0030] Figure 4 The present invention discloses a nuclear magnetic spectrum of the methacrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBMA) prepared by the present invention.

[0031] Figure 5 The nuclear magnetic spectrum of the acrylic acid amide urea zwitterionic sulfobetaine monomer (ASC-SBAA) prepared by the present invention is shown.

[0032] Figure 6 The present invention discloses a nuclear magnetic spectrum of the methacrylic acid amido urea zwitterionic sulfobetaine monomer (ASC-SBMA) prepared by the present invention.

[0033] Figure 7The diagram is a schematic diagram of the compression resistance of the methacrylic acid amide urea zwitterionic carboxybetaine (ASC-CBMA) hydrogel prepared by the present invention.

[0034] Figure 8 It is a stress-strain schematic diagram of the methacrylic acid amide urea zwitterionic carboxy betaine (ASC-CBMA) hydrogel prepared by the present invention.

[0035] Fig. 9 It is a schematic diagram of the self-healing of the methacrylic acid amide urea zwitterionic carboxybetaine (ASC-CBMA) hydrogel prepared by the present invention.

[0036] Fig.10 The figure is a schematic diagram of the injectability of the methacrylic acid amide urea zwitterionic carboxybetaine (ASC-CBMA) hydrogel freeze-dried powder prepared by the present invention after reconstitution. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the scope of the present invention is not limited thereto.

[0038] The nuclear magnetic resonance spectrometer (AVANCE AV 400MHz) was used to perform nuclear magnetic H spectrum test ( 1 H NMR), using deuterated water or deuterated dimethyl sulfoxide as solvent, the test was carried out at room temperature, and the analysis was performed using MestReNova software. The nuclear magnetic hydrogen spectrum proved that all monomers were successfully synthesized. The mechanical properties of the prepared multi-hydrogen bonded zwitterionic hydrogel were tested using a universal pressure tester (CTM6002), and the origin software was used for analysis and drawing. The test results showed that the hydrogel had high mechanical strength. The anti-bovine serum albumin (BSA) adhesion ability of the hydrogel was tested using a microprotein quantification kit (BCA). The results showed that the prepared hydrogel had excellent anti-fouling properties. The excellent self-healing and injectable properties of the hydrogel and the hydrogel lyophilized powder were also demonstrated through experiments.

[0039] Example 1

[0040] (1) The synthesis method of acrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBAA) is as follows:

[0041] Step 1: Weigh 1.411 g (10 mmol) of isocyanoethyl acrylate and dissolve it in 5 ml of anhydrous tetrahydrofuran, and add 0.2% hydroquinone inhibitor (2.2 mg). Then weigh 1.172 g (10 mmol) of 2-(dimethylamino)acetic hydrazide and dissolve it in 25 ml of anhydrous tetrahydrofuran. Add isocyanoethyl methacrylate dropwise to the tetrahydrofuran solution of 2-(dimethylamino)acetic hydrazide under low temperature stirring, and stir overnight (12 hours) at 5°C. After centrifugation, a white precipitate is obtained, which is further washed three times with ether and dried in a vacuum drying oven to obtain a vinyl intermediate containing tertiary amino and amidourea groups (double bonds without methyl groups (ASC)). Its structural formula is shown below:

[0042]

[0043] 1 H NMR spectrum is attached Figure 1 As shown, 1 H NMR (D 2 O): δ = 6.38; 5.95 (H 1 , CH 2 =CH-); 6.17(H 2 , CH 2 =CH-); 4.22(H 3 , -COO-CH 2 -); 3.46(H 4 , -CH 2 -NH-); 3.16(H 8 , -NH-CO-CH 2 -); 2.30(H 9、10 ,-N-(CH 3 ) 2 )ppm. This proves that the vinyl intermediate containing tertiary amine and amidourea groups (double bond without methyl group (ASC)) was successfully synthesized.

[0044] Step 2: Weigh 2.5828g (10mmol) of ASC intermediate and dissolve it in 25ml of anhydrous tetrahydrofuran under heating at 45°C, and add 0.2% hydroquinone inhibitor (2.2mg). Then weigh 0.7205g (10mmol) of β-propiolactone and add it dropwise to the ASC intermediate solution, stirring while adding. After the addition is complete, rinse with 200 microliters of anhydrous tetrahydrofuran, react overnight at 45°C under nitrogen protection, and obtain a white precipitate after centrifugation. It is further washed three times with ether and dried in a vacuum drying oven to obtain the final product. Dry in a drying oven for one day to obtain the final acrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBAA). Its structural formula is as follows:

[0045]

[0046] 1 H NMR spectrum is attached Figure 2 As shown, 1 H NMR (D 2 O): δ = 6.39; 5.95 (H 1 , CH 2 =CH-); 6.17(H 2 , CH 2 =CH-); 4.23(H 3 , -COO-CH 2 -); 3.47(H 4 , -CH 2 -NH-); 4.14(H 8 , -NH-CO-CH 2 -); 3.27(H 9、10 ,-N-(CH 3 ) 2 -); 3.77(H 11 ,-N-(CH 3 ) 2 -CH 2 -); 2.70(H 12 , -CH 2 -COO) ppm. Acrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBAA) was successfully synthesized.

[0047] (2) The preparation method of ASC-CBAA hydrogel is as follows:

[0048] The prepared zwitterionic monomer ASC-CBAA was weighed and dissolved in deionized water to prepare a solution with a molar concentration of 5 mol / L. 0.1% of photoinitiator was added and cured under ultraviolet light for 30 minutes, then demolded and soaked in deionized water for 3 days to reach swelling equilibrium, and finally ASC-CBAA hydrogel was obtained. Its polymer structure is shown below:

[0049]

[0050] Where m is the degree of polymerization, and its value is 6000;

[0051] The antifouling performance of the hydrogel prepared by the present invention was tested. Before the test, the tested hydrogel reached swelling equilibrium in a phosphate buffer solution, and then was cut into uniform discs (5 mm in diameter and 1 mm in thickness) with a biopsy punch. A 2mg / mL 200μL bovine serum albumin seawater solution was incubated with a 96-well TCPS at 37°C for 2 hours, and then rinsed 5 times with a phosphate buffer solution to remove free bovine serum albumin. Then, the hydrogel sample was immersed in 200wt% sodium dodecyl sulfate and immersed at 37°C for 1 hour. The amount of protein adhesion on the hydrogel was then determined using a BCA protein kit, and the absorbance of all samples at 562nm was recorded using a plate reader. The results showed that the amount of ASC-CBAA (5mol / L) hydrogel protein adhesion was 0.770ug / cm 2 Far lower than the national standard (≤3ug / cm 2 ), its protein adhesion is less than one-thirtieth of that of polystyrene plate, and is higher than that of hydroxyethyl methacrylate (6.405ug / cm 2 ) is much lower, and is even lower than the best antifouling property reported so far, carboxybetaine methacrylate (CBMA), thanks to the strong hydration of the zwitterionic part. The compression resistance of the hydrogel was further tested at room temperature using a universal testing machine (CTM6002) with a 500N load cell. Before the experiment, all tested hydrogels were balanced in water and then cut into cylinders (5mm in diameter and 2mm in thickness) with a biopsy punch. The crosshead speed was set to 1 mm / min. The results show that the compressive fracture strain of the ASC-CBAA (5mol / L, without crosslinking agent) hydrogel is 0.8MPa, which is almost twice that of CBMA. This shows that the introduction of multiple hydrogen bonds significantly enhances the mechanical properties of the hydrogel.

[0052] Example 2

[0053] (1) The synthesis method of methacrylic acid amidourea zwitterionic carboxy betaine monomer (ASC-CBMA) is as follows:

[0054] Step 1: 2.068 g (13.33 mmol) of isocyanoethyl methacrylate and 4.6854 g (39.99 mmol) of 2-(dimethylamino)acetohydrazide were weighed and dissolved in anhydrous tetrahydrofuran in a molar ratio of 1:3, and 0.2% hydroquinone polymerization inhibitor (3 mg) was added. Under low temperature stirring, isocyanoethyl methacrylate was added dropwise to the tetrahydrofuran solution of 2-(dimethylamino)acetohydrazide, and the reaction was carried out overnight for 12 hours under nitrogen protection. A white precipitate was obtained after centrifugation, and further washed three times with ether, and dried in a vacuum drying oven to obtain a vinyl intermediate (ASC-MA) with a double bond having a methyl group and containing a tertiary amino group and an amidourea group. Its structural formula is shown below:

[0055]

[0056] 1 H NMR spectrum is attached Figure 3 As shown, 1 H NMR (DMSO): δ = 6.06; 5.68 (H 1 , CH 2 =(CH 3 )-COO-); 1.88(H 2 , CH 2 =(CH 3 )-COO-); 4.05(H 3 , -COO-CH 2 -); 3.28(H 4 , -CH 2 -NH-); 6.42(H 5 , -CH 2 -NH-); 9.34(H 6 , -CO-NH-NH-); 7.82(H 7 , -CO-NH-NH-); 2.90(H 8 , -CO-CH2-); 2.20(H 9、10 ,-N-(CH 3 ) 2 )ppm. It proved that the vinyl intermediate (double bond with methyl group (ASC-MA)) containing tertiary amine and amidourea group was successfully synthesized.

[0057] Step 2: Weigh 1.815g (6.665mmol) of the ASC-MA intermediate obtained in step 1 in a molar ratio of 1:1.1 and dissolve it in 25ml of anhydrous tetrahydrofuran. Add 0.2% hydroquinone inhibitor (1.5mg) and heat to dissolve at 50°C. Then weigh 0.528g (7.33mmol) of β-propiolactone and add it dropwise to the ASC-MA intermediate solution, stirring while adding. After the addition is complete, rinse with 200 microliters of anhydrous tetrahydrofuran, stir the reaction at 50°C overnight for 12 hours, centrifuge to obtain a white precipitate, and further wash it three times with ether. After drying in a vacuum drying oven, the final methacrylic acid amide urea zwitterionic carboxybetaine monomer (ASC-CBMA) is obtained. Its structural formula is as follows:

[0058]

[0059] 1 H NMR spectrum is attached Figure 4 As shown, 1 H NMR (D 2 O): δ = 6.14; 5.73 (H 1 , CH2 =(CH 3 )-COO-); 1.93(H 2 , CH 2 =(CH 3 )-COO-); 4.26(H 3 , -COO-CH 2 -); 3.52(H 4 , -CH 2 -NH-); 4.17(H 8 , -CO-CH 2 -); 3.30(H 9、10 ,-N-(CH 3 ) 2 -); 3.81(H 11 ,-N-(CH 3 ) 2 -CH 2 -); 2.73(H 12 , -CH 2 -COO) ppm. It proves that methacrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBMA) was successfully synthesized.

[0060] (2) The preparation method of ASC-CBMA hydrogel is as follows:

[0061] The prepared zwitterionic monomer ASC-CBMA was weighed and dissolved in deionized water to prepare a solution with a molar concentration of 5 mol / L. 0.1% of photoinitiator was added and cured under ultraviolet light for 180 minutes, then demolded and soaked in deionized water for 3 days to reach swelling equilibrium, and finally ASC-CBMA hydrogel was obtained. Its polymer structure is shown below:

[0062]

[0063] Where m is the degree of polymerization, and its value is 4500;

[0064] (3) The preparation method of ASC-CBMA microgel is as follows:

[0065] The ASC-CBMA gel that reached swelling equilibrium in water was extruded into microgel through an extrusion mesh with a diameter of 25 μm, and then freeze-dried into powder by a vacuum freeze dryer. It was then redissolved in deionized water at a solid content of 22% to obtain an injectable gel.

[0066] Columnar ASC-CBMA (5 mol / L) and CBMA hydrogels were prepared by syringe mold, in which ASC-CBMA was not added with cross-linking agent, such as Figure 7As shown in the figure, ASC-CBMA can form a gel by itself without adding an additional cross-linking agent. The mechanical properties of the hydrogel were evaluated by pressing with fingers. The ASC-CBMA hydrogel remained intact even when pressed to 90% strain. After the pressing force was removed, the gel returned to its original shape. The compressive fracture stress of the hydrogel was further tested under the same conditions as in Example 1. The results showed that the average fracture stress of the ASC-CBMA (5 mol / L, no cross-linking agent) hydrogel in water was 3 MPa, and the highest could reach 3.2 MPa (as shown in the figure). Figure 8 ).

[0067] The protein adhesion test method in Example 1 was used to test the anti-protein adhesion performance of ASC-CBMA. The results showed that the protein adhesion amount of ASC-CBMA (5 mol / L) hydrogel was 2.551 ug / cm 2 Lower than national standard (≤3ug / cm 2 ), which is also much lower than the biocompatible material hydroxyethyl methacrylate, and fully meets the requirements for in vivo application.

[0068] The self-healing properties of ASC-CBMA were tested. Fig. 9 As shown, the cured hydrogel strips were cut into three sections, and then stained with rhodamine, trypan blue and methyl orange respectively. The gels were then placed along the cuts, and the hydrogel strips healed immediately. Then they were placed at 37 degrees for 12 hours to allow the broken physical bonds to fully heal. The healed gel strips can withstand repeated bending, pulling and compression and remain intact. This is attributed to the hydrogen bonding and electrostatic interactions in ASC-CBMA. These two forces are physical interactions. When the two gels are in contact, the broken hydrogen bonds and electrostatic interactions between zwitterions can be formed again.

[0069] The hydrogel freeze-dried powder prepared in step 4 was dissolved in deionized water at 20 wt% to re-prepare the gel and test the injectability of the re-dissolved gel. Fig.10 As shown, the hydrogel powder immediately gels after being dissolved in water. The gel can be extruded through a 22G needle, and the gel can be directly extruded into a continuous line in water. This injectable property is also attributed to the hydrogen bonding effect in the ASC-CBMA hydrogel and the electrostatic interaction of the zwitterionic part.

[0070] Example 3

[0071] (1) The synthesis method of acrylic acid amide urea zwitterionic sulfobetaine monomer (ASC-SBAA) is as follows:

[0072] 1.523 g (6.665 mmol) of the ASC intermediate obtained in step 1 of Example 1 was weighed in a molar ratio of 1:2 and dissolved in 25 ml of anhydrous tetrahydrofuran. 0.2% hydroquinone inhibitor (1.5 mg) was added and heated at 50°C to dissolve. Then 1.627 g (13.33 mmol) of 1,3-propane sultone was weighed and added dropwise to the ASC intermediate solution while stirring. After the addition was complete, it was rinsed with 200 microliters of anhydrous tetrahydrofuran, stirred and reacted at 60°C for 12 hours, and a white precipitate was obtained after centrifugation. It was further washed three times with ether and dried in a vacuum drying oven to obtain an acrylic acid amide urea zwitterionic sulfobetaine monomer (ASC-SBAA). Its structure is shown below:

[0073]

[0074] 1 H NMR spectrum Figure 5 As shown, 1 H NMR (D 2 0): δ = 6.39; 5.95 (H 1 , CH 2 =CH-); 6.17(H 2 , CH 2 =CH-); 4.24(H 3 , -COO-CH 2 -); 3.69(H 4 , -CH 2 -NH-); 4.19(H 8 , -NH-CO-CH 2 -); 3.30(H 9、10 ,-N-(CH 3 ) 2 -); 3.48(H 11 ,-N-(CH 3 ) 2 -CH 2 -); 2.25(H 12 , -CH 2 -CH 2 -CH 2 -); 2.97(H 12 , -CH 2 -SO 3 )ppm. This proves that the acrylic acid amide urea zwitterionic sulfobetaine monomer (ASC-SBAA) was successfully synthesized.

[0075] (2) The preparation method of ASC-SBAA hydrogel is as follows:

[0076] The prepared zwitterionic monomer ASC-SBAA was weighed and dissolved in deionized water to prepare a solution with a molar concentration of 4 mol / L. 1% of photoinitiator was added and cured under ultraviolet light for 1 hour, then demolded and soaked in deionized water for 3 days to reach swelling equilibrium, and finally ASC-SBAA hydrogel was obtained. Its polymer molecular structure is shown below:

[0077]

[0078] Where m is the degree of polymerization, and its value is 5700;

[0079] (3) The preparation method of ASC-SBAA microgel is as follows:

[0080] The ASC-SBAA gel that reached swelling equilibrium in water was extruded through a mesh with a diameter of 10 μm to form a microgel, and then freeze-dried into powder using a vacuum freeze dryer. The powder was then redissolved in deionized water at a solid content of 50 wt% to obtain an injectable gel.

[0081] Example 4

[0082] (1) The synthesis method of methacrylic acid amidourea zwitterionic sulfobetaine monomer (ASC-SBMA) is as follows:

[0083] 1.815 g (6.665 mmol) of the ASC-MA intermediate obtained in step 1 of Example 2 was weighed and dissolved in 25 ml of anhydrous tetrahydrofuran in a molar ratio of 1:1.5, and 0.2% hydroquinone inhibitor (1.5 mg) was added and heated at 50°C to dissolve. Then 1.220 g (10 mmol) of 1,3-propane sultone was weighed and added dropwise to the ASC-MA intermediate solution, stirring while adding dropwise. After the addition was complete, it was rinsed with 200 microliters of anhydrous tetrahydrofuran, stirred at 50°C for 12 hours, and a white precipitate was obtained after centrifugation, which was further washed three times with ether and dried in a vacuum drying oven to obtain a methacrylic acid amido urea zwitterionic sulfobetaine monomer (ASC-SBMA). Its structure is shown below:

[0084]

[0085] 1 H NMR spectrum Figure 6 As shown, 1 H NMR (D 2 O): δ = 6.11; 5.70 (H 1 , CH 2 =(CH 3 )-COO-); 1.90(H 2 , CH 2 =(CH 3 )-COO-); 4.22(H3 , -COO-CH 2 -); 3.69(H 4 , -CH 2 -NH-); 4.18(H 8 , -NH-CO-CH 2 -); 3.30(H 9、10 ,-N-(CH 3 ) 2 -); 3.48(H 11 ,-N-(CH 3 ) 2 -CH 2 -); 2.25(H 12 , -CH 2 -CH 2 -CH 2 -); 2.97(H 12 , -CH 2 -SO 3 )ppm. It proved that methacrylic acid amido urea zwitterionic sulfobetaine monomer (ASC-SBMA) was successfully synthesized.

[0086] (2) The preparation method of ASC-SBMA hydrogel is as follows:

[0087] The prepared zwitterionic monomer ASC-SBMA was weighed and dissolved in deionized water to prepare a solution with a molar concentration of 6 mol / L. 2% of photoinitiator was added, and the solution was cured under ultraviolet light for 10 minutes, then demolded and soaked in deionized water for 3 days to reach swelling equilibrium, and finally ASC-SBMA hydrogel was obtained. Its polymer structure is shown below:

[0088]

[0089] Where m is the degree of polymerization, and its value is 4200;

[0090] (3) The preparation method of ASC-SBMA microgel is as follows:

[0091] Step 3, the ASC-SBMA gel that has reached swelling equilibrium in water is extruded through a mesh with a diameter of 500 μm to form a microgel, and then freeze-dried into powder using a vacuum freeze dryer, and then redissolved in deionized water at a solid content of 10 wt% to obtain an injectable gel.

[0092] Example 5

[0093] (1) The synthesis method of acrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBAA-3) is as follows:

[0094] Step 1: Weigh 1.411 g (10 mmol) of isocyanoethyl acrylate and dissolve it in 5 ml of anhydrous tetrahydrofuran, and add 0.2% hydroquinone inhibitor (2.2 mg). Then weigh 1.452 g (10 mmol) of dimethylaminohydrazide and dissolve it in 25 ml of anhydrous tetrahydrofuran. Add isocyanoethyl methacrylate dropwise to the tetrahydrofuran solution of dimethylaminohydrazide under low temperature stirring, and stir overnight at 5°C for 12 hours. After centrifugation, a white precipitate is obtained, which is further washed three times with ether and dried in a vacuum drying oven to obtain a vinyl intermediate (ASC-3) with no methyl groups on the double bonds and containing tertiary amino and amidourea groups. Its structural formula is shown below:

[0095]

[0096] Where n = 3;

[0097] The above dimethylaminohydrazide structure is shown below:

[0098]

[0099] Where n = 3;

[0100] Step 2: Weigh 2.863g (10mmol) of ASC-3 intermediate and dissolve it in 25ml of anhydrous tetrahydrofuran at 45°C, and add 0.2% hydroquinone inhibitor (2.2mg). Then weigh 0.7205g (10mmol) of β-propiolactone and add it dropwise to the ASC-3 intermediate solution, stirring while adding. After the addition is complete, rinse with 200 microliters of anhydrous tetrahydrofuran, react overnight at 45°C under nitrogen protection, and centrifuge to obtain a white precipitate, which is further washed three times with ether and dried in a vacuum drying oven to obtain the final product. Dry in a drying oven for one day to obtain acrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBAA-3). Its structural formula is as follows:

[0101]

[0102] Where n = 3;

[0103] (2) The preparation method of ASC-CBAA-3 hydrogel is as follows:

[0104] The prepared zwitterionic monomer ASC-CBAA-3 was weighed and dissolved in deionized water to prepare a solution with a molar concentration of 3 mol / L. 0.1% of photoinitiator was added, and the solution was cured under ultraviolet light for 180 minutes, then demolded and soaked in deionized water for 3 days to reach swelling equilibrium, and finally ASC-CBAA-3 hydrogel was obtained. Its polymer structure is shown below:

[0105]

[0106] Where m is the degree of polymerization, which is 5500, and n = 3;

[0107] (3) The preparation method of ASC-CBAA-3 microgel is as follows:

[0108] The ASC-CBAA-3 gel that reached swelling equilibrium in water was extruded through a mesh with a diameter of 25 μm to form a microgel, and then freeze-dried into powder using a vacuum freeze dryer. The powder was then redissolved in deionized water at a solid content of 1% to obtain a microgel solution.

[0109] Example 6

[0110] (1) The synthesis method of methacrylic acid amido urea zwitterionic carboxy betaine monomer (ASC-CBMA-5) is as follows:

[0111] Step 1: Weigh 1.552g (10mmol) of isocyanoethyl methacrylate and dissolve it in 5ml of anhydrous acetone, and add 0.2% hydroquinone inhibitor (2.2mg). Then weigh 1.732g (10mmol) of dimethylaminohydrazide and dissolve it in 25ml of anhydrous acetone. Add isocyanoethyl methacrylate dropwise to the acetone solution of dimethylaminohydrazide under low temperature stirring, and stir overnight at 5°C for 12 hours. After centrifugation, a white precipitate is obtained, which is further washed three times with ether and dried in a vacuum drying oven to obtain a vinyl intermediate (ASC-MA-5) with a double bond having a methyl group and containing a tertiary amino group and an amidourea group. Its structural formula is shown below:

[0112]

[0113] Where n = 5;

[0114] The above dimethylaminohydrazide structure is shown below:

[0115]

[0116] Where n = 5;

[0117] Step 2: Weigh 3.283g (10mmol) of ASC-MA-5 intermediate and dissolve it in 25ml of anhydrous acetone under heating at 45°C, then weigh 0.721g (10mmol) of β-propiolactone and add it dropwise to the ASC-5 intermediate solution, stirring while adding dropwise, rinse with 200 microliters of anhydrous acetone after the addition is complete, react overnight at 45°C under nitrogen protection, centrifuge to obtain a white precipitate, and further wash it three times with ether, dry it in a vacuum drying oven to obtain the final product, dry it in a drying oven for one day to obtain methacrylic acid amide urea zwitterionic carboxy betaine monomer (ASC-CBMA-5). Its structural formula is as follows:

[0118]

[0119] Where n = 5;

[0120] (2) The preparation method of ASC-CBMA-5 hydrogel is as follows:

[0121] The prepared zwitterionic monomer ASC-CBMA-5 was weighed and dissolved in deionized water to prepare a solution with a molar concentration of 2 mol / L. 0.5% of photoinitiator was added, and the solution was cured under ultraviolet light for 60 minutes, then demolded and soaked in deionized water for 3 days to reach swelling equilibrium, and finally ASC-CBMA-5 hydrogel was obtained. Its polymer structure is shown below:

[0122]

[0123] Where m is the degree of polymerization, which is 4800, and n = 5;

[0124] (2) The preparation method of ASC-CBMA-5 microgel is as follows:

[0125] The ASC-CBMA-5 gel that reached swelling equilibrium in water was extruded through a mesh with a diameter of 50 μm to form a microgel, and then freeze-dried into powder using a vacuum freeze dryer. The powder was then redissolved in deionized water at a solid content of 10% to obtain an injectable gel.

[0126] According to the content of the present invention, the process parameters can be adjusted to achieve the preparation of hydrogels, and the performance shown by the test is basically consistent with that of the present invention. The above is an exemplary description of the present invention. Without departing from the core of the present invention, any simple deformation, modification or equivalent replacement that can be made by other technicians in this field without spending creative labor falls within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, self-healing amidourea zwitterionic hydrogel, It is characterized in that The amidourea zwitterionic monomer is dissolved in water or a phosphate buffer solution to prepare a solution with a molar concentration of 1 to 6 mol / L, and then a photoinitiator or a thermal initiator is added at a molar ratio of 0.1 to 2% relative to the monomer, and then injected into a closed mold to initiate polymerization of the monomer by photoinitiation or thermal initiation. After a period of reaction time, the mold is opened to take out the hydrogel, and the unreacted monomer is removed by soaking in water for at least 1 day to obtain an amidourea zwitterionic hydrogel, and the structural formula thereof is as follows: Among them, R 1 CH 3 or H; R 2 for m is the degree of polymerization of the zwitterionic monomer, and its value is 20-6000; n is an integer of 1-5.

2. The method for preparing the amidourea zwitterionic hydrogel according to claim 1, It is characterized in that The initiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173) or 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (photoinitiator 2959) or ammonium persulfate.

3. The method for preparing the amidourea zwitterionic hydrogel according to claim 1, It is characterized in that When 2-hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173) or 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (photoinitiator 2959) is selected as the initiator for cross-linking, it is placed in an ultraviolet light cross-linking instrument to initiate monomer polymerization, and the reaction time is 10 to 180 minutes. When ammonium persulfate is selected as the thermal initiator, it is placed in an oven for heating to initiate monomer polymerization, the polymerization reaction temperature is 60 to 80° C., and the polymerization time is 12 hours.

4. A method for preparing a high-strength, self-healing amidourea zwitterionic hydrogel according to claim 1, It is characterized in that The synthesis method of amidourea zwitterionic monomer is as follows: Step 1: reacting isocyanoethyl (meth)acrylate and dimethylaminohydrazide to obtain a vinyl intermediate containing a tertiary amine group and an amidourea group, that is, weighing isocyanoethyl (meth)acrylate and dimethylaminohydrazide at a monomer molar ratio of 1:(1-5) and dissolving them in anhydrous tetrahydrofuran or anhydrous acetone, adding isocyanoethyl (meth)acrylate dropwise to the tetrahydrofuran or acetone solution of dimethylaminohydrazide under low temperature stirring, reacting at 5-10° C. for 12 hours under nitrogen protection, centrifuging to obtain a white precipitate, and further washing with ether and drying to obtain a vinyl intermediate containing a tertiary amine and an amidourea group, the structural formula of the amidourea zwitterionic monomer is as follows: Where R is CH 3 or H; n is an integer from 1 to 5, The chemical structure of isocyanoethyl (meth)acrylate is shown below: Where R is CH 3 or H; The chemical structure of dimethylaminohydrazide is shown below: Where n is an integer from 1 to 5, Step 2: The vinyl intermediate containing a tertiary amine group and an amidourea group obtained in step 1 is reacted with β-propiolactone or 1,3-propane sultone to obtain an amidourea zwitterionic monomer, i.e., the intermediate obtained in step 1 is weighed and dissolved in 25 ml of anhydrous tetrahydrofuran or anhydrous acetone in a molar ratio of 1:(1-2) and heated to dissolve at 45-60° C., then 1-2 equivalents of β-propiolactone or 1,3-propane sultone are weighed and added dropwise to the intermediate solution while stirring. After the addition is complete, the mixture is rinsed with 200 μl of anhydrous tetrahydrofuran or anhydrous acetone, stirred and reacted at 45-60° C. for 12 hours, and a white precipitate is obtained after centrifugation. The mixture is further washed with ether and dried to obtain an amidourea zwitterionic monomer, the chemical structure of which is shown below: Among them, R 1 CH 3 or H; R 2 for n is an integer of 1-5.

5. A method for preparing a high-strength, self-healing amidourea zwitterionic hydrogel according to claim 1, It is characterized in that The hydrogel can be further extruded into microgel through an extrusion net with a diameter of 10 to 500 μm, and then dried by a vacuum freeze dryer to obtain hydrogel freeze-dried powder that is easy to store. After the freeze-dried powder is dissolved in deionized water or phosphate buffer solution at a mass ratio of 1 to 50%, a high-strength, self-healing amidourea zwitterionic hydrogel can be obtained.

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