Preparation method of double-crosslinking self-healing medical hydrogel

Abstract

The invention relates to a preparation method of medical hydrogel, in particular to a preparation method of bi-crosslinking self-healing medical hydrogel which is prepared from carboxymethyl chitosan, tannic acid and 2-formylphenylboronic acid. Tannic acid and 2-formylphenylboronic acid are subjected to a boric acid complexation reaction and then subjected to a Schiff base reaction with carboxymethyl chitosan, and the self-healing hydrogel is formed. The tannic acid can inhibit inflammatory cells from generating inflammatory mediators and can also inhibit migration of the inflammatory cells, and the prepared hydrogel has the advantages of good self-healing performance, good anti-inflammatory activity, no stimulation to wounds and the like, and is suitable for treating the wounds.

Description

Technical Field

[0001] The invention relates to a method for preparing a medical hydrogel, in particular to a method for preparing a double-crosslinked self-healing medical hydrogel. Background Art

[0002] As the first barrier to isolate and protect the human body, the skin resists a variety of physical, chemical and microbial attacks. When the damage exceeds the limit that the skin can bear, it will cause physical trauma such as abrasions, cuts, and tears, as well as chemical trauma such as corrosion, burns, and radiation. When the epidermis, dermis and part of the subcutaneous tissue of the skin are damaged, the self-repair ability cannot heal the wound, and medical dressings are needed for auxiliary repair.

[0003] The healing of human wounds is the result of the coordinated action of various parts of the wound. It is a dynamic and complex process of self-repair and tissue regeneration. After experiencing trauma such as burns, incisions, and lacerations, the skin epidermal structure will quickly begin to repair. When the skin is traumatized, it generally undergoes a healing process with four overlapping stages: hemostasis, inflammation, proliferation, and remodeling.

[0004] Traditional wound dressings such as gauze and medical cotton keep the wound surface dry, but at the same time have disadvantages such as easy adhesion and non-sealing. Self-healing hydrogel as a new material for wound dressing can solve these problems well. It is a colloidal substance formed by physical and chemical cross-linking of natural macromolecules or synthetic macromolecules, with a three-dimensional network structure. Hydrogel has high water content, and the water content can usually reach 70%-90% of its own weight. This property is conducive to providing a cool and moist environment for the wound and maintaining the moisture of the wound; because the hydrogel is soft in texture, smooth on the surface and has no fiber pores, it can prevent the wound from contacting external bacteria, which is conducive to the effectiveness of the dressing loaded with drugs; it has good swelling performance, can absorb a large amount of wound exudate, and avoid the problem of adhesion to the wound, and can also automatically restore its structure and function after damage.

[0005] Tannic acid (TA), also known as tannic acid, is a natural high molecular weight water-soluble polyphenol compound. The central part is a glucose nucleus, and the five connected hydroxyl groups are combined with gallic acid groups through ester groups. It contains a total of five pyrogallol groups and five catechol end groups, and the structure contains many bonding points that can produce interactions. Tannic acid can inhibit inflammatory cells from producing inflammatory mediators, and can also inhibit the migration of inflammatory cells to accelerate wound healing. Carboxymethyl chitosan (CMC) is a derivative obtained by chemical modification of the natural polymer material chitosan (CS). Compared with CS, CMC has better biocompatibility, water solubility, biodegradability and antibacterial activity. 2-Formylphenylboronic acid belongs to the benzaldehyde derivatives, contains boric acid groups and aldehyde groups, and can form boric acid ester bonds and Schiff base bonds with substances containing amino groups and ortho-dihydroxyl groups as a crosslinking agent. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a double-crosslinked self-healing medical hydrogel. The method prepares the self-healing hydrogel by double crosslinking carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid, and the tannic acid and 2-formylphenylboronic acid undergo a boric acid complexation reaction, and then undergo a Schiff base reaction with carboxymethyl chitosan to form a self-healing hydrogel, thereby promoting wound healing.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a double cross-linked self-healing medical hydrogel, which is prepared by carboxymethyl chitosan, tannic acid, and 2-formylphenylboronic acid. Tannic acid and 2-formylphenylboronic acid undergo a boric acid complexation reaction, and then undergo a Schiff base reaction with carboxymethyl chitosan to obtain a self-healing hydrogel. The hydrogel exhibits good self-healing properties and can quickly return to its original state under conditions where external forces change. Tannic acid can inhibit inflammatory cells from producing inflammatory mediators and can also inhibit the migration of inflammatory cells to accelerate wound healing. The gel matrix components include carboxymethyl chitosan, tannic acid, 2-formylphenylboronic acid, and PBS buffer solution. The carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid self-healing hydrogel is prepared from the following components in mass percentage: 2%-4% carboxymethyl chitosan, 0.5%-2% tannic acid, 0.25%-0.5% 2-formylphenylboronic acid, and 90%-95% water;

[0009] The specific preparation process is as follows:

[0010] (1) Boric acid complexation of tannic acid and 2-formylphenylboronic acid: accurately weigh 0.5-1.0 g of 2-formylphenylboronic acid and dissolve it in an appropriate amount of PBS (pH=7.4) buffer solution, then accurately weigh 1.0-4.0 g of tannic acid and dissolve it therein, stirring until the tannic acid is completely dissolved;

[0011] (2) Tannic acid and 2-formylphenylboronic acid are reacted with carboxymethyl chitosan through Schiff base reaction to prepare a self-healing hydrogel: Tannic acid and 2-formylphenylboronic acid are mixed evenly until they are completely dissolved, and then carboxymethyl chitosan is weighed and dissolved in deionized water. The two solutions are mixed and poured into a mold to obtain a hydrogel through cross-linking reaction.

[0012] In the method for preparing a double-crosslinked self-healing medical hydrogel, the mass ratio of the carboxymethyl chitosan to tannic acid to 2-formylphenylboronic acid is 12:2:1; 12:4:1; 6:4:1; 6:4:1; 16:2:1.

[0013] The preparation method of the double-crosslinked self-healing medical hydrogel comprises the following raw materials: 0.4-0.8 g of carboxymethyl chitosan and 20 ml of deionized water.

[0014] The preparation method of the double-crosslinked self-healing medical hydrogel, the raw materials of the tannic acid-2-formylphenylboric acid solution are: 1.0-4.0g of tannic acid, 0.5-1.0g of 2-formylphenylboric acid, 0.2g of potassium chloride, 4g of sodium chloride, 1.44g of disodium hydrogen phosphate, 0.24g of potassium dihydrogen phosphate, and 1000ml of deionized water.

[0015] The advantages and effects of the present invention are:

[0016] 1. The preparation method of the self-healing hydrogel of the present invention uses carboxymethyl chitosan, tannic acid, and 2-formylphenylboronic acid as raw materials to prepare the self-healing anti-inflammatory hydrogel, and screens its optimal formulation through single factor and response surface experiments. The gelation time of the hydrogel is 13 minutes, the gelation temperature is 25±1°C, and the pH is 7.4.

[0017] 2. The hydrogel of the present invention exhibits good self-healing properties and can return to its original state under the condition of changes in external force. Tannic acid can inhibit inflammatory cells from producing inflammatory mediators and can also inhibit the migration of inflammatory cells, thereby accelerating wound healing. The hydrogel has good biocompatibility; it is non-toxic to the human body; it has rapid self-healing ability and can quickly restore its structure and function after being damaged; it has high tensile strength; and the self-healing speed of the hydrogel can be adjusted by changing the prescription ratio. The hydrogel exhibits excellent performance in terms of self-healing ability and non-toxicity, and is suitable for accelerating wound healing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the preparation method of the present invention;

[0019] Figure 2 is the response surface diagram of the hydrogel of the present invention;

[0020] Figure 3This is a diagram of the self-healing and adhesion performance of the hydrogel of the present invention;

[0021] Figure 4 It is the rheological diagram of the hydrogel of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below in conjunction with the embodiments shown in the accompanying drawings.

[0023] The preparation steps of a carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double-crosslinked self-healing hydrogel prepared by the present invention include:

[0024] (1) Boric acid complexation of tannic acid and 2-formylphenylboronic acid: accurately weigh 0.5-1.0 g of 2-formylphenylboronic acid and dissolve it in an appropriate amount of PBS (pH = 7.4) buffer solution, then accurately weigh 1.0-4.0 g of tannic acid and dissolve it in the buffer solution, stirring until the tannic acid is completely dissolved.

[0025] (2) Tannic acid and 2-formylphenylboronic acid react with carboxymethyl chitosan through Schiff base reaction to prepare self-healing hydrogel: Tannic acid and 2-formylphenylboronic acid are mixed evenly until they are completely dissolved, and then carboxymethyl chitosan is weighed and dissolved in deionized water. The two solutions are mixed and poured into a mold, and a cross-linking reaction is performed at a certain temperature to obtain a hydrogel. The process is shown in FIG. Figure 1

[0026] A carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double cross-linked self-healing hydrogel was prepared. The feed ratio, gel temperature and gel pH were determined through single factor experiments.

[0027] 1. Single Factor Experiment

[0028] A carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double cross-linked self-healing hydrogel was prepared. The feed ratio, gel temperature and gel pH were determined through single factor experiments.

[0029] The investigation of the feed mass ratio includes: setting the feed ratio of tannic acid to 2-formylphenylboronic acid to 1:1, 2:1, 3:1, 1:2, 1:3, and 1:4, placing the prepared solution in a vial, inverting it every 30 seconds at room temperature, checking the flow state of the hydrogel in the vial, and waiting for the gel solution in the vial to stop flowing after being inverted for 30 seconds to determine that gel is formed, based on which the feed ratio range can be determined.

[0030] The temperature investigation includes: placing the configured double-cross-linked self-healing hydrogel solution in a vial, starting from 10°C in a constant temperature water bath, increasing the temperature by 5°C every 10 minutes, inverting the vial every 30 seconds, checking the state of the gel in the vial, and when the gel solution in the vial does not flow after being inverted for 30 seconds, it is determined that a gel has been formed, and the temperature range can be determined accordingly.

[0031] The pH investigation includes: preparing a double-crosslinked self-healing hydrogel, dissolving 2-formylphenylboronic acid and tannic acid in buffer solutions with pH values ​​of 6, 7, 8, and 9, respectively, and then dropping them into a carboxymethyl chitosan solution, placing the prepared solution in a vial, and inverting it every 30 seconds at room temperature to check the state of the hydrogel in the vial. When the gel solution in the vial does not flow after being inverted for 30 seconds, it is determined that a gel is formed, and the pH range can be determined accordingly.

[0032] Single factor test results:

[0033] Table 1 Investigation results of feed mass ratio

[0034]

[0035]

[0036] Table 2 Temperature investigation results

[0037] Temperature / ℃ Invert for 30 seconds to see if it flows 10 yes 15 yes 20 no 25 no 30 no 35 yes 40 yes

[0038] Table 3 pH investigation results

[0039] pH Invert for 30 seconds to see if it flows 6 yes 7 no 8 no 9 yes

[0040] Through single factor experiments, it was determined that the mass ratio of gelling agent was 1:1, 2:1, 3:1, the temperature range was 20-30℃, and the pH range was 7-8.

[0041] 2. Star point design-response surface optimization

[0042] Based on the single-factor investigation test, temperature (A), pH (B), the mass ratio of tannic acid to 2-formylphenylboronic acid (C), and self-healing time (T) were selected as the response value, and Design-Expert 13 was used for star point design.

[0043] Table 4 Independent factors and their coding levels in star point design

[0044]

[0045] Central composite design-response surface experiment results:

[0046] Table 5 Tests and results

[0047]

[0048]

[0049] Through response surface testing ( Figure 2 ), the optimal formulation of the double-crosslinked self-healing hydrogel can be obtained

[0050] Table 6 Optimal formulation of double cross-linked self-healing hydrogel

[0051] Temperature / ℃ pH(B) Quality Ratio 25 7.5 2

[0052] Examples are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention provides the following preferred embodiments:

[0053] The invention prepares a self-healing hydrogel with carboxymethyl chitosan, tannic acid and 2-formylphenylboronic acid as a gel matrix, and examines the performance of the hydrogel.

[0054] Example 1: The present invention provides a method for preparing a carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double cross-linked self-healing hydrogel, comprising:

[0055] Step 1: Weigh 0.5 g of 2-formylphenylboronic acid into a beaker, add 200 ml of PBS buffer solution, and stir at room temperature until it is completely dissolved to obtain a 0.25% 2-formylphenylboronic acid solution.

[0056] Step 2: Weigh 1 g of tannic acid and dissolve it in a certain concentration of 2-formylphenylboronic acid solution, and stir at room temperature until it is completely dissolved.

[0057] Step 3: Weigh 0.6 g of carboxymethyl chitosan and dissolve it in 20 ml of deionized water, and stir at room temperature until it is completely dissolved to obtain a carboxymethyl chitosan solution with a concentration of 3%.

[0058] Step 4: Mix the carboxymethyl chitosan solution and the 2-formylphenylboronic acid solution at room temperature, let it stand, and when it stops flowing when inverted, a hydrogel is obtained.

[0059] Example 2: The present invention provides a method for preparing a carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double-crosslinked self-healing hydrogel, comprising:

[0060] Step 1: Weigh 0.5 g of 2-formylphenylboronic acid into a beaker, add 200 ml of PBS buffer solution, and stir at room temperature until it is completely dissolved to obtain a 0.25% 2-formylphenylboronic acid solution.

[0061] Step 2: Weigh 2 g of tannic acid and dissolve it in a certain concentration of 2-formylphenylboronic acid solution, and stir at room temperature until it is completely dissolved.

[0062] Step 3: Weigh 0.6 g of carboxymethyl chitosan and dissolve it in 20 ml of deionized water, and stir at room temperature until it is completely dissolved to obtain a carboxymethyl chitosan solution with a concentration of 3%.

[0063] Step 4: Mix the carboxymethyl chitosan solution and the 2-formylphenylboronic acid solution at room temperature, let it stand, and when it stops flowing when inverted, a hydrogel is obtained.

[0064] Example 3: The present invention provides a method for preparing a carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double cross-linked self-healing hydrogel, comprising:

[0065] Step 1: Weigh 2 g of 2-formylphenylboronic acid into a beaker, add 200 ml of PBS buffer solution, and stir at room temperature until it is completely dissolved to obtain a 1% 2-formylphenylboronic acid solution.

[0066] Step 2: Weigh 1 g of tannic acid and dissolve it in a certain concentration of 2-formylphenylboronic acid solution, and stir at room temperature until it is completely dissolved.

[0067] Step 3: Weigh 0.6 g of carboxymethyl chitosan and dissolve it in 20 ml of deionized water, and stir at room temperature until it is completely dissolved to obtain a carboxymethyl chitosan solution with a concentration of 3%.

[0068] Step 4: Mix the carboxymethyl chitosan solution and the 2-formylphenylboronic acid solution at room temperature, let it stand, and when it stops flowing when inverted, a hydrogel is obtained.

[0069] Comparison 1: The present invention provides a method for preparing a carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double-crosslinked self-healing hydrogel, comprising:

[0070] Step 1: Weigh 3 g of 2-formylphenylboronic acid into a beaker, add 200 ml of PBS buffer solution, and stir at room temperature until it is completely dissolved to obtain a 1% 2-formylphenylboronic acid solution.

[0071] Step 2: Weigh 1 g of tannic acid and dissolve it in a certain concentration of 2-formylphenylboronic acid solution, and stir at room temperature until it is completely dissolved.

[0072] Step 3: Weigh 0.6 g of carboxymethyl chitosan and dissolve it in 20 ml of deionized water, and stir at room temperature until it is completely dissolved to obtain a carboxymethyl chitosan solution with a concentration of 3%.

[0073] Step 4: Mix the carboxymethyl chitosan solution and the 2-formylphenylboronic acid solution at room temperature, let it stand, and when it stops flowing when inverted, a hydrogel is obtained.

[0074] Comparison 2: The present invention provides a method for preparing a carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid double-crosslinked self-healing hydrogel, comprising:

[0075] Step 1: Weigh 0.5 g of 2-formylphenylboronic acid into a beaker, add 200 ml of PBS buffer solution, and stir at room temperature until it is completely dissolved to obtain a 0.25% 2-formylphenylboronic acid solution.

[0076] Step 2: Weigh 3 g of tannic acid and dissolve it in a certain concentration of 2-formylphenylboronic acid solution, and stir at room temperature until it is completely dissolved.

[0077] Step 3: Weigh 0.6 g of carboxymethyl chitosan and dissolve it in 20 ml of deionized water, and stir at room temperature until it is completely dissolved to obtain a carboxymethyl chitosan solution with a concentration of 3%.

[0078] Step 4: Mix the carboxymethyl chitosan solution and the 2-formylphenylboronic acid solution at room temperature, let it stand, and when it stops flowing when inverted, a hydrogel is obtained.

[0079] Table 7 Example results

[0080] Examples Gelation time Self-healing properties Example 1 quick generally Example 2 Faster good Example 3 No glue / Comparison 1 No glue / Comparison 2 Faster good

[0081] It can be seen from Example 1, Example 2 and Comparative 2 that a high concentration of tannic acid affects the self-healing performance, and it can be seen from Example 1, Example 3 and Comparative 1 that a high concentration of 2-formylphenylboronic acid will lead to a lack of gelation.

[0082] The adhesion and rheology tests of the hydrogels proved that the hydrogels had good adhesion properties ( Figure 3 ) and the internal structure of the hydrogel is stable ( Figure 4 ).

Claims

1. A method for preparing a double-crosslinked self-healing medical hydrogel, characterized in that: The method adopts carboxymethyl chitosan, tannic acid and 2-formylphenylboronic acid to prepare a hydrogel, wherein tannic acid and 2-formylphenylboronic acid undergo a boric acid complexation reaction, and then undergo a Schiff base reaction with carboxymethyl chitosan to obtain a self-healing hydrogel; the gel matrix components include carboxymethyl chitosan, tannic acid, 2-formylphenylboronic acid and PBS buffer solution; the carboxymethyl chitosan-tannic acid-2-formylphenylboronic acid self-healing hydrogel is prepared from the following components in mass percentage: 2%-4% of carboxymethyl chitosan, 0.5%-2% of tannic acid, 0.25%-0.5% of 2-formylphenylboronic acid and 90%-95% of water; The specific preparation process is as follows: (1) Boric acid complexation of tannic acid and 2-formylphenylboronic acid: accurately weigh 0.5-1.0 g of 2-formylphenylboronic acid and dissolve it in an appropriate amount of PBS (pH=7.4) buffer solution, then accurately weigh 1.0-4.0 g of tannic acid and dissolve it therein, stirring until the tannic acid is completely dissolved; (2) Tannic acid and 2-formylphenylboronic acid are reacted with carboxymethyl chitosan through Schiff base reaction to prepare a self-healing hydrogel: Tannic acid and 2-formylphenylboronic acid are mixed evenly until they are completely dissolved, and then carboxymethyl chitosan is weighed and dissolved in deionized water. The two solutions are mixed and poured into a mold to obtain a hydrogel through cross-linking reaction.

2. The method for preparing a double-crosslinked self-healing medical hydrogel according to claim 1, characterized in that: The mass ratio of the carboxymethyl chitosan to tannic acid to 2-formylphenylboronic acid is 12:2:1; 12：4：1；6：2：1；6：4：1；16：2：1。 3. The method for preparing a double-crosslinked self-healing medical hydrogel according to claim 1, characterized in that: The raw materials of the carboxymethyl chitosan solution are: 0.4-0.8 g of carboxymethyl chitosan and 20 ml of deionized water.

4. The method for preparing a double-crosslinked self-healing medical hydrogel according to claim 1, characterized in that: The raw materials of the tannic acid-2-formylphenylboric acid solution are: 1.0-4.0g of tannic acid, 0.5-1.0g of 2-formylphenylboric acid, 0.2g of potassium chloride, 4g of sodium chloride, 1.44g of disodium hydrogen phosphate, 0.24g of potassium dihydrogen phosphate, and 1000ml of deionized water.

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