Injectable gel and its preparation method and application

Abstract

The application discloses an injectable gel and a preparation method and application thereof. Firstly, a dopamine grafted and modified natural high polymer is prepared and synthesized, a dynamic Schiff base chemical bond is formed by using aldehyde groups and amino groups on a chitosan derivative, catechol groups of dopamine are endowed with super strong adhesion like mussels, and an injectable self-healing viscous gel is constructed. Tannic acid silver nanoparticles are prepared by using an in-situ reduction method, and a dynamic Schiff base chemical bond is formed by using amino groups on molecular chains of a gel matrix and quinone groups on the tannic acid silver nanoparticles, so that the silver nanoparticles are uniformly dispersed in the gel. The injectable gel has the advantages of rapid gel formation, self-healing, tissue adhesion, high-efficiency synergistic antibacterial activity and promotion of macrophage M2 polarization and anti-inflammatory effect, can be injected and adhered to periodontal pocket tissues without being damaged by external force, can efficiently kill periodontal bacteria, promote macrophage M2 polarization to play an anti-inflammatory role, and finally promotes alveolar bone regeneration.

Description

Technical Field

[0001] This invention relates to the field of medical gel technology, and in particular to an injectable gel, its preparation method, and its application. Background Technology

[0002] Periodontitis is an inflammatory reaction and one of the most common dental diseases, often leading to periodontal tissue loss, tooth loosening, and even tooth loss. Therefore, the treatment of periodontitis needs to focus on two key aspects: antibacterial and anti-inflammatory treatments to induce periodontal tissue regeneration. Currently, there are various anti-inflammatory treatment methods available clinically, such as teeth cleaning, periodontal pocket irrigation, and periodontal therapy. In addition, clinicians often use guided tissue regeneration, periodontal bone grafting, and growth factor therapy to repair periodontal tissue defects. However, using only one treatment method cannot achieve satisfactory results; multiple methods are usually required in combination. Furthermore, many unresolved issues remain, such as significant trauma, long treatment cycles, and uncertain efficacy. Therefore, there is an urgent need to introduce a new treatment method that simultaneously combats bacteria and inflammation and induces periodontal tissue regeneration, which is precisely the challenge that urgently needs to be addressed in clinical treatment.

[0003] Injectable gels have attracted increasing attention from researchers due to their excellent properties, such as (1) the ability to encapsulate cells or drugs in situ and act directly on the affected area, improving bioavailability; (2) the ability to premix drugs with sol solutions in vitro, making preoperative preparation convenient and operation simple; (3) the ability to flow in vitro, making them easy to fill and suitable for industrial production; (4) the ability of the initial sol liquid to fill defects of any shape and adhere closely to the defect site, allowing for adhesion to different tissues; and (5) good biocompatibility and the ability to be customized for different properties. However, most current injectable gels require the initial sol liquid to be injected into the body to form a gel, and the initial sol liquid often has unclear targeting due to uncontrollable flowability. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a solution.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of the present invention proposes an injectable gel.

[0007] A second aspect of the present invention provides a method for preparing an injectable gel.

[0008] A third aspect of the invention proposes an application of an injectable gel.

[0009] According to a first aspect of the present invention, an injectable gel is provided, comprising a gel matrix and silver tannic acid nanoparticles, wherein the silver tannic acid nanoparticles are loaded on the gel matrix, and the raw materials of the gel matrix include dopamine-grafted modified oxidized natural polymers and chitosan derivatives, wherein the injectable gel has a three-dimensional network structure.

[0010] In this invention, the catechol groups of dopamine endow the gel with super strong mussel-like adhesion properties. The amino groups on the gel molecular chain form dynamic Schiff base chemical bonds with the quinone groups on the silver tannin nanoparticles, which makes the silver tannin nanoparticles uniformly dispersed in the gel, enhancing mechanical and tissue adhesion properties, and endowing it with photothermal and highly efficient synergistic antibacterial activity of silver nanoparticles. In addition, the release of silver tannin nanoparticles can promote the polarization of macrophage M2 and exert an anti-inflammatory effect.

[0011] In some embodiments of the present invention, the gel matrix contains chemical bonds and hydrogen bonds, the chemical bonds including carbon-nitrogen Schiff dynamic bonds.

[0012] In some embodiments of the present invention, the dopamine-grafted modified oxidized natural polymer and the chitosan derivative are cross-linked by carbon-nitrogen Schiff dynamic bonds, the chitosan derivative is cross-linked internally by hydrogen bonds, and the silver tannic acid nanoparticles are connected to the gel matrix by carbon-nitrogen Schiff dynamic bonds.

[0013] In some embodiments of the present invention, the natural polymer includes at least one of natural polymers whose six-membered ring units contain groups that can be oxidized to aldehyde or carboxyl groups.

[0014] In some preferred embodiments of the present invention, the natural polymer is selected from at least one of hyaluronic acid, sodium alginate, and chondroitin sulfate.

[0015] In some preferred embodiments of the present invention, the chitosan derivative is selected from at least one of hydroxyethyl chitosan, quaternary ammonium chitosan, and carboxymethyl chitosan.

[0016] In some preferred embodiments of the present invention, the average particle size of the silver tannin nanoparticles is 50 nm to 150 nm.

[0017] In some preferred embodiments of the present invention, the silver tannin nanoparticle content in the injectable gel is 0.1 mg / mL to 5 mg / mL.

[0018] In some preferred embodiments of the present invention, the mass ratio of the dopamine-grafted modified oxidized natural polymer and the chitosan derivative in the gel matrix is ​​1 to 10:1.

[0019] In some preferred embodiments of the present invention, the grafting rate of dopamine in the dopamine-grafted modified oxidized natural polymer is 5% to 50%.

[0020] In some preferred embodiments of the present invention, the dopamine includes dopamine hydrochloride.

[0021] In this invention, dopamine hydrochloride has better solubility and stability than dopamine, which is more conducive to the smooth progress of the reaction.

[0022] According to a second aspect of the present invention, a method for preparing the injectable gel described in the first aspect is provided, comprising the following steps:

[0023] Silver tannic acid nanoparticles were mixed with a chitosan derivative solution to obtain a gel prepolymer solution. A dopamine-grafted modified oxidized natural polymer solution was then added to crosslink the solution, thus obtaining the final product.

[0024] In this invention, the quinone groups in the silver tannin nanoparticles can form Schiff base dynamic bonds with the amino groups in the chitosan derivatives. The silver tannin nanoparticles are first mixed with the chitosan derivatives, and the dynamic chemical bonds can make them uniformly dispersed in the prepolymer solution. When they are mixed with another prepolymer solution to form a gel, their uniform dispersion in the gel can also be guaranteed. If they are added in other ways or in other orders, the silver tannin nanoparticles may settle in the prepolymer solution, resulting in uneven dispersion.

[0025] In some embodiments of the present invention, the silver tannin nanoparticles are prepared by in-situ reduction.

[0026] In some embodiments of the present invention, the volume ratio of the gel prepolymer solution to the dopamine-grafted modified oxidized natural polymer solution is (1-2):(1-2).

[0027] In some embodiments of the present invention, the crosslinking includes vortex mixing or rapid stirring for a time of 5 to 10 seconds.

[0028] In some embodiments of the present invention, the mass concentration of the chitosan derivative in the gel prepolymer solution is (0.01-0.04) g / mL.

[0029] In some embodiments of the present invention, the mass concentration of the silver tannin nanoparticles in the gel prepolymer solution is 0.05–10 mg / mL, preferably 0.05–5 mg / mL.

[0030] In some embodiments of the present invention, the concentration of the dopamine-grafted modified oxidized natural polymer solution is (0.05-0.1) g / mL.

[0031] In some preferred embodiments of the present invention, the method for preparing the silver tannic acid nanoparticles includes: slowly adding AgNO3 solution dropwise to an aqueous solution of tannic acid with pH = 9-10, reacting, and freeze-drying to obtain the nanoparticles;

[0032] The reaction temperature is 25–30°C, and the reaction time is 24–36 h; the concentration of the tannic acid aqueous solution is (0.01–0.05) g / mL, the concentration of the AgNO3 solution is (0.5–5) mg / mL, and the molar ratio of tannic acid to AgNO3 is 25–100:1.

[0033] In some preferred embodiments of the present invention, the preparation of the dopamine-grafted modified oxidized natural polymer includes: adding a dopamine solution dropwise to a mixed solution of the oxidized natural polymer and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS), reacting in the absence of oxygen, dialyzing, and lyophilizing to obtain the product;

[0034] The mass ratio of the oxidized natural polymer to dopamine is 1:(0.1-0.8); the mass ratio of EDC to NHS is (0.8-1.2):(0.2-0.4); the solvent of the mixed solution is morpholine ethanesulfonic acid (MES) buffer; the reaction time is 20-30 h, and the temperature is 25-30 °C; the dialysis molecular weight is 3000-10000, and the dialysis time is 48-96 h; the freeze-drying temperature is -80 to -60 °C, and the time is 48-96 h.

[0035] In some preferred embodiments of the present invention, the solvent for both the gel prepolymer solution and the chitosan derivative solution is PBS buffer.

[0036] In some more preferred embodiments of the present invention, the pH of the gel prepolymer solution is 8 to 10.

[0037] In this invention, a dopamine-grafted modified oxidized natural polymer is first synthesized. Dynamic Schiff base bonds are formed between the aldehyde groups on the oxidized natural polymer and the amino groups on the chitosan derivative. The dopamine catechol groups impart super-strong adhesion to the mussel-like material, constructing an injectable self-healing adhesive gel. Tannic acid silver nanoparticles are prepared using an in-situ reduction method. Dynamic Schiff base bonds are formed between the amino groups on the gel matrix molecular chain and the quinone groups on the tannic acid silver nanoparticles, allowing the tannic acid silver nanoparticles to be uniformly dispersed in the gel. This enhances mechanical and tissue adhesion properties and endows the gel with photothermal and highly efficient synergistic antibacterial activity of the silver nanoparticles. Furthermore, the release of tannic acid silver nanoparticles can promote M2 polarization of macrophages, exerting an anti-inflammatory effect.

[0038] According to a third aspect of the invention, the use of the injectable gel described in the first aspect in the preparation of a medicament for treating periodontitis is proposed.

[0039] The beneficial effects of this invention are:

[0040] (1) The raw materials of this invention are all water-soluble natural polymers or modified natural polymers. The polymer modification is also done using aqueous solutions, which is green and environmentally friendly. Furthermore, this invention only requires vortex mixing of the pre-liquid to quickly form a gel, with a gelation time of <30s, making the preparation simple.

[0041] (2) This invention utilizes the aldehyde groups on oxidized natural polymers to form dynamic Schiff base chemical bonds with the amino groups on chitosan derivatives, and the dopamine catechol groups endow the mussel-like material with super strong adhesion, thus constructing an injectable self-healing adhesive gel. By forming dynamic Schiff base chemical bonds between the amino groups on the gel matrix molecular chain and the quinone groups on the silver tannic acid nanoparticles, the silver tannic acid nanoparticles are uniformly dispersed in the gel, enhancing mechanical and tissue adhesion properties.

[0042] (3) The gel prepared by the present invention has rapid gelation, is injectable, self-healing, tissue adhesion, highly efficient synergistic antibacterial activity and macrophage M2 polarization anti-inflammatory effect. It can be injected and adhered to the periodontal pocket tissue without being damaged by external force. After photothermal treatment, it can effectively kill periodontal bacteria. Moreover, the release of silver tannic acid nanoparticles can promote macrophage M2 polarization to exert anti-inflammatory effect, and ultimately promote alveolar bone regeneration. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the injectable gel prepared in Example 1 of the present invention;

[0044] Figure 2 This is a schematic diagram illustrating the function of the injectable gel of the present invention in preparing a drug for treating periodontitis;

[0045] Figure 3 The rheological test diagrams are for the injectable gels prepared in Example 1 and Comparative Example 2 of this invention. Detailed Implementation

[0046] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0047] In the following examples and comparative examples, room temperature refers to 25–30°C.

[0048] Example 1

[0049] This embodiment prepares an injectable gel, and the specific process is as follows:

[0050] (1) Preparation of silver tannic acid nanoparticles:

[0051] Dissolve 0.1 g of tannic acid in 10 mL of deionized water, adjust the pH to 9 with an appropriate amount of 1 M NaOH solution, and then slowly add 3 mL of 0.5 mg / mL AgNO3 solution to the above solution. React at room temperature for 24 h, freeze dry at -80 °C for 72 h, and ultrasonically disperse in PBS at a concentration of 20 mg / mL to obtain a silver tannic acid nanoparticle solution, which is stored at 4 °C for later use.

[0052] (2) Preparation of dopamine hydrochloride-grafted modified oxidized hyaluronic acid:

[0053] 2 g of hyaluronic acid (HA) was dissolved in 200 mL of pure water, and then 1 mL of 0.5 M sodium periodate aqueous solution was added dropwise. The reaction was carried out at room temperature in the dark for 2 h. Then, 45 μL of glycerol was added and the mixture was stirred for 1 h to terminate the reaction. The mixture was then dialyzed (MWCO3500) for 2 days. The purified product was lyophilized at -80 °C for 72 h to obtain oxidized hyaluronic acid, which was stored at 4 °C for later use.

[0054] 1 g of oxidized hyaluronic acid was dissolved in 80 mL of 0.1 M MES buffer (pH = 4.7) and stirred at 25 °C until a clear solution was obtained. 400 mg EDC and 200 mg NHS were added, and the pH was adjusted to 5.0. After stirring at 300 rpm for 30 min, 0.1 g of dopamine hydrochloride was dissolved in 10 mL of 0.1 M MES buffer (pH = 5) and added dropwise to the above reaction system. The mixture was stirred overnight at 25 °C under N2 atmosphere, dialyzed (MWCO 3500) for 72 h, and lyophilized at -80 °C for 72 h to obtain dopamine hydrochloride modified oxidized hyaluronic acid.

[0055]

[0056] (3) Preparation of gel prepolymer solution:

[0057] Dissolve 1g of dopamine hydrochloride grafted modified oxidized hyaluronic acid obtained in step (2) in 10mL PBS, and adjust the pH to 8 with an appropriate amount of 1M NaOH to obtain gel prepolymer solution A.

[0058] Dissolve 1g of hydroxyethyl chitosan in 30mL of PBS, and then add 0.5mL of the silver tannic acid nanoparticle solution prepared in step (1) to obtain gel prepolymer solution B.

[0059] (4) Gel preparation:

[0060] The gel prepolymer solutions A and B obtained in step (3) are thoroughly mixed by high-speed vortexing for 5 seconds at a volume ratio of 1:1 to obtain the injectable gel.

[0061] Example 2

[0062] This embodiment prepares an injectable gel, and the specific process is as follows:

[0063] (1) Preparation of silver tannic acid nanoparticles:

[0064] Dissolve 0.5 g of tannic acid in 30 mL of deionized water, adjust the pH to 10 with an appropriate amount of 1 M NaOH solution, then slowly add 3 mL of 5 mg / mL AgNO3 solution to the above solution, react at room temperature for 36 h, freeze dry at -80 °C for 72 h, and ultrasonically disperse in PBS at a concentration of 80 mg / mL to obtain a silver tannic acid nanoparticle solution, which is stored at 4 °C for later use.

[0065] (2) Preparation of dopamine hydrochloride-grafted modified oxidized hyaluronic acid:

[0066] 2 g of hyaluronic acid (HA) was dissolved in 150 mL of pure water, and then 6 mL of 0.5 M sodium periodate aqueous solution was added dropwise. The reaction was carried out at room temperature in the dark for 3 h. Then, 300 μL of glycerol was added and the mixture was stirred for 2 h to terminate the reaction. The mixture was then dialyzed (MWCO5000) for 4 days. The purified product was lyophilized at -80 °C for 72 h to obtain oxidized hyaluronic acid, which was stored at 4 °C for later use.

[0067] 1 g of oxidized hyaluronic acid was dissolved in 150 mL of 0.1 M MES buffer (pH = 4.7) and stirred at 25 °C until a clear solution was obtained. 700 mg EDC and 500 mg NHS were added, and the pH was adjusted to 5.0. After stirring at 300 rpm for 30 min, 0.8 g of dopamine hydrochloride was dissolved in 10 mL of 0.1 M MES buffer (pH = 5.5) and added dropwise to the above reaction system. The mixture was stirred overnight at 25 °C under N2 atmosphere, dialyzed (MWCO 5000) for 72 h, and lyophilized at -80 °C for 72 h to obtain dopamine hydrochloride modified oxidized hyaluronic acid.

[0068] (3) Preparation of gel prepolymer solution:

[0069] Dissolve 1g of dopamine hydrochloride grafted modified oxidized hyaluronic acid obtained in step (2) in 20mL PBS, and adjust the pH to 10 with an appropriate amount of 1M NaOH to obtain gel prepolymer solution A.

[0070] Dissolve 1g of hydroxyethyl chitosan in 100mL of PBS, and then add 5mL of the silver tannic acid nanoparticle solution prepared in step (1) to obtain gel prepolymer solution B.

[0071] (4) Gel preparation:

[0072] The gel prepolymer solutions A and B obtained in step (3) are thoroughly mixed by high-speed vortexing for 5 seconds at a volume ratio of 1:1 to obtain the injectable gel.

[0073] Example 3

[0074] This embodiment prepares an injectable gel, and the specific process is as follows:

[0075] (1) Preparation of silver tannic acid nanoparticles:

[0076] Dissolve 0.3 g of tannic acid in 15 mL of deionized water, adjust the pH to 9 with an appropriate amount of 1 M NaOH solution, and then slowly add 3 mL of 2 mg / mL AgNO3 solution to the above solution. React at room temperature for 36 h, freeze dry at -80 °C for 72 h, and ultrasonically disperse in PBS at a concentration of 40 mg / mL to obtain a silver tannic acid nanoparticle solution, which is stored at 4 °C for later use.

[0077] (2) Preparation of dopamine hydrochloride-grafted modified oxidized hyaluronic acid:

[0078] Dissolve 2g of hyaluronic acid (HA) in 150mL of pure water, then add 2mL of 0.5M sodium periodate aqueous solution dropwise and react at room temperature in the dark for 3h. Then add 100μL of glycerol and continue stirring for 1h to terminate the reaction. Dialyze (MWCO5000) for 4 days, then freeze-dry the purified product at -80℃ for 72h to obtain oxidized hyaluronic acid, which is stored at 4℃ for later use.

[0079] 1 g of oxidized hyaluronic acid was dissolved in 100 mL of 0.1 M MES buffer (pH = 4.7) and stirred at 25 °C until a clear solution was obtained. 500 mg EDC and 300 mg NHS were added, and the pH was adjusted to 5.0. After stirring at 300 rpm for 30 min, 0.4 g of dopamine hydrochloride was dissolved in 10 mL of 0.1 M MES buffer (pH = 5.5) and added dropwise to the above reaction system. The mixture was stirred overnight at 25 °C under N2 atmosphere, dialyzed (MWCO 5000) for 72 h, and lyophilized at -80 °C for 72 h to obtain dopamine hydrochloride modified oxidized hyaluronic acid.

[0080] (3) Preparation of gel prepolymer solution:

[0081] Dissolve 1g of dopamine hydrochloride grafted modified oxidized hyaluronic acid obtained in step (2) in 20mL PBS, and adjust the pH to 9 with an appropriate amount of 1M NaOH to obtain gel prepolymer solution A.

[0082] Dissolve 1g of hydroxyethyl chitosan in 60mL of PBS, and then add 2mL of the silver tannic acid nanoparticle solution prepared in step (1) to obtain gel prepolymer solution B.

[0083] (4) Gel preparation:

[0084] The gel prepolymer solutions A and B obtained in step (3) are thoroughly mixed by high-speed vortexing for 5 seconds at a volume ratio of 1:1 to obtain the injectable gel.

[0085] Example 4

[0086] This embodiment prepares an injectable gel, and the specific process is as follows:

[0087] (1) Preparation of silver tannic acid nanoparticles:

[0088] Dissolve 0.3 g of tannic acid in 15 mL of deionized water, adjust the pH to 9 with an appropriate amount of 1 M NaOH solution, and then slowly add 3 mL of 3 mg / mL AgNO3 solution to the above solution. React at room temperature for 30 h, freeze dry at -80 °C for 72 h, and ultrasonically disperse in PBS at a concentration of 50 mg / mL to obtain a silver tannic acid nanoparticle solution, which is stored at 4 °C for later use.

[0089] (2) Preparation of dopamine hydrochloride-grafted modified sodium alginate:

[0090] Dissolve 2g of sodium alginate in 200mL of pure water, then add 4mL of 0.5M sodium periodate aqueous solution dropwise and react at room temperature in the dark for 3h. Then add 200μL of glycerol and continue stirring for 1h to terminate the reaction. Then dialyze (MWCO 5000) for 3 days. Freeze-dry the purified product at -80℃ for 72h to obtain oxidized sodium alginate, which is stored at 4℃ for later use.

[0091] 1 g of oxidized sodium alginate was dissolved in 100 mL of 0.1 M MES buffer (pH = 4.7) and stirred at 25 °C until a clear solution was obtained. 500 mg EDC and 300 mg NHS were added, and the pH was adjusted to 5.0. After stirring at 300 rpm for 30 min, 0.4 g of dopamine hydrochloride was dissolved in 10 mL of 0.1 M MES buffer (pH = 5.5) and added dropwise to the above reaction system. The mixture was stirred overnight at 25 °C under N2 atmosphere, dialyzed (MWCO 5000) for 72 h, and lyophilized at -80 °C for 72 h to obtain dopamine hydrochloride modified oxidized sodium alginate.

[0092] (3) Preparation of gel prepolymer solution:

[0093] Dissolve 1g of dopamine hydrochloride grafted modified sodium alginate obtained in step (2) in 15mL PBS, and adjust the pH to 9 with an appropriate amount of 1M NaOH to obtain gel prepolymer solution A.

[0094] Dissolve 1g of hydroxyethyl chitosan in 80mL of PBS, and then add 2mL of the silver tannic acid nanoparticle solution prepared in step (1) to obtain gel prepolymer solution B.

[0095] (4) Gel preparation:

[0096] The gel prepolymer solutions A and B obtained in step (3) are thoroughly mixed by high-speed vortexing for 5 seconds at a volume ratio of 1:1 to obtain the injectable gel.

[0097] Comparative Example 1

[0098] This comparative example prepared an injectable gel, the main difference from Examples 1-3 being that it did not contain silver tannic acid nanoparticles. The specific process is as follows:

[0099] (1) Preparation of dopamine hydrochloride graft-modified oxidized hyaluronic acid:

[0100] Dissolve 2g of hyaluronic acid (HA) in 150mL of pure water, then add 2mL of 0.5M sodium periodate aqueous solution dropwise and react at room temperature in the dark for 3h. Then add 100μL of glycerol and continue stirring for 1h to terminate the reaction. Dialyze (MWCO5000) for 4 days, then freeze-dry the purified product at -80℃ for 72h to obtain oxidized hyaluronic acid, which is stored at 4℃ for later use.

[0101] 1 g of oxidized hyaluronic acid was dissolved in 100 mL of 0.1 M MES buffer (pH = 4.7) and stirred at 25 °C until a clear solution was obtained. 500 mg EDC and 300 mg NHS were added, and the pH was adjusted to 5.0. After stirring at 300 rpm for 30 min, 0.4 g of dopamine hydrochloride was dissolved in 10 mL of 0.1 M MES buffer (pH = 5.5) and added dropwise to the above reaction system. The mixture was stirred overnight at 25 °C under N2 atmosphere, dialyzed for 72 h, and lyophilized at -80 °C for 72 h to obtain dopamine hydrochloride modified oxidized hyaluronic acid.

[0102] (2) Preparation of gel prepolymer solution:

[0103] Dissolve 1g of dopamine hydrochloride grafted modified oxidized hyaluronic acid obtained in step (2) in 20mL PBS, and adjust the pH to 9 with an appropriate amount of 1M NaOH to obtain gel prepolymer solution A.

[0104] Dissolve 1g of hydroxyethyl chitosan in 60mL of PBS to obtain gel prepolymer solution B.

[0105] (4) Gel preparation:

[0106] The gel prepolymer solutions A and B obtained in step (3) are thoroughly mixed by high-speed vortexing for 5 seconds at a volume ratio of 1:1 to obtain the injectable gel.

[0107] Comparative Example 2

[0108] This comparative example prepared an injectable gel, the main difference from Examples 1-3 being that the oxidized hyaluronic acid was not modified with dopamine hydrochloride. The specific process is as follows:

[0109] (1) Preparation of oxidized hyaluronic acid:

[0110] Dissolve 2g of hyaluronic acid (HA) in 100mL of pure water, then add 1mL of 0.5M sodium periodate aqueous solution dropwise and react at room temperature in the dark for 2h. Then add 45μL of glycerol and continue stirring for 1h to terminate the reaction. Dialyze (MWCO5000) for 2 days, then freeze-dry the purified product at -80℃ for 72h to obtain oxidized hyaluronic acid, which is stored at 4℃ for later use.

[0111] (2) Preparation of hydrogel prepolymer solution:

[0112] Dissolve 1g of oxidized hyaluronic acid obtained in step (1) in 10mL PBS to obtain hydrogel prepolymer solution A, and dissolve 1g of hydroxyethyl chitosan in 15mL PBS to obtain hydrogel prepolymer solution B.

[0113] (3) Preparation of hydrogels:

[0114] The hydrogel prepolymer A and B obtained in step (2) are thoroughly mixed by passing them through a high-speed vortex for 5 seconds at a volume ratio of 1:1.

[0115] Test case

[0116] The gelation time of the injectable gels prepared in Examples 1-4 and Comparative Example 2 was measured by the inverted method. All gels formed rapidly with a gelation time of <30s.

[0117] The photothermal and nanoparticle synergistic bactericidal effects were determined by the plate method.

[0118] The photothermal activity of the gel was measured by irradiating the gel samples with an 808 nm laser for 10 minutes at a laser density of 1.5 W / cm². 2 .

[0119] The in vitro antibacterial activity of the gel alone, or nanoparticles alone, and synergistic bactericidal activity were evaluated using a plate-laying method. 500 μL of sterile gel was transferred to a 24-well plate, and then 100 μL of *E. coli* or *S. aureus* bacterial suspension (10⁷ CFU mL⁻¹) was added to the gel surface and treated with a NIR laser (808 nm, 1 W / cm²). 2 Irradiate for 10 minutes. After keeping all groups in contact with bacteria for 24 hours, 1 mL of sterile PBS is introduced into each well to resuspend the bacteria. Bacterial count is determined using the plating method.

[0120] The test results are shown in Table 1 below:

[0121] Table 1

[0122]

[0123]

[0124] The results above show that the injectable gel prepared by this invention has excellent photothermal and nanoparticle-based synergistic bactericidal properties.

[0125] Rheological tests were performed on the hydrogels prepared in Examples 1-4 and Comparative Example 2, respectively: viscosity changes at different shear frequencies were measured to study injectability; and the self-healing behavior of the gels was evaluated by measuring the changes and recovery of G' and G” under alternating strain cycles of low and high strain. The results are shown in Table 2 and 3. Figure 3 (Taking Example 1 and Comparative Example 2 as examples), from Figure 3 It can be seen that the products of Example 1 and Comparative Example 2 both exhibit rheological shear thinning, indicating their injectability. The remaining examples are similar. Figure 3 The results of Example 1 are similar.

[0126] Fresh pigskin was used to evaluate the adhesion ability of the gel to tissues. The adhesive strength of the hydrogels prepared in Examples 1-4 and Comparative Example 2 was tested by using a lap shear test.

[0127] The cytotoxicity of the hydrogels prepared in Examples 1 to 4 was tested using the CCK-8 assay.

[0128] In vitro macrophage experiments were conducted, and the changes in M1 and M2 markers were tested using iNOS / CD206 fluorescence double staining. The ratio of the fluorescence intensity of the M2 marker CD206 in the treatment group to that in the periodontitis group was calculated to study the effect of silver tannic acid nanoparticles in the hydrogels prepared in Examples 1-4 on promoting M2 polarization.

[0129] A rat model of periodontal tissue defects induced by periodontitis was established through animal experiments using a simple silk suture ligation method combined with a high-sugar diet. The specific steps were as follows: Rats were weighed and anesthetized with inhaled gas. After anesthesia, the rats were fixed in a supine position on the experimental table. A self-made mouth gag was used to fully expose the maxillary molars. After disinfection, the gingiva was separated to the bone surface. A silk suture was placed in the distal interproximal space on the palatal side of the left maxillary first molar, wrapped around the left maxillary first permanent molar, and then sutured and fixed on the mesial palatal side. It was confirmed that the suture was not loose and was located subgingivally. The suture was checked every 2 days for loosening. After establishing the rat model of periodontal tissue defects induced by periodontitis, 30 μL of the hydrogel prepared in Examples 1-4 was injected submucoperiosteally at the midpoint of the buccal palatal side of the left maxillary first molar, near the alveolar ridge crest, every 3 days until 14 days post-operation. The rats were then anesthetized and euthanized, and the following tests were performed:

[0130] Micro-CT was used to observe and measure the alveolar bone resorption of the left maxillary first molar in each group of rats. The distance between the cementoenamel junction and the alveolar ridge crest of the left maxillary first molar (CEJ-ABC distance) was measured. Then the ratio of the experimental treatment group to the periodontitis group was calculated. The periodontitis group had the largest CEJ-ABC value, and the CEJ-ABC value of the treatment group decreased after alveolar bone regeneration.

[0131] The test results are shown in Table 2 below:

[0132] Table 2

[0133]

[0134]

[0135] The test results above show that Comparative Example 2, without dopamine hydrochloride modification, exhibits poor self-healing and tissue adhesion properties. The injectable gel prepared in this invention possesses injectability, self-healing, and tissue adhesion properties. Cytotoxicity testing showed no toxicity. Its application in periodontitis treatment demonstrates highly efficient antibacterial activity through the synergistic effect of photothermal and nanoparticle interactions. M2-labeled fluorescence staining analysis revealed that silver tannic acid nanoparticles can promote M2 polarization, thereby exerting an anti-inflammatory effect and promoting alveolar bone regeneration.

[0136] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An injectable gel, characterized in that: The invention comprises a gel matrix and silver tannic acid nanoparticles, wherein the silver tannic acid nanoparticles are loaded onto the gel matrix. The raw materials of the gel matrix include dopamine-grafted modified oxidized natural polymers and chitosan derivatives. The injectable gel has a three-dimensional network structure. The natural polymer is selected from at least one of hyaluronic acid, sodium alginate, and chondroitin sulfate. The chitosan derivative is selected from at least one of hydroxyethyl chitosan, quaternary ammonium chitosan, and carboxymethyl chitosan. The aldehyde groups on the oxidized natural polymer form dynamic Schiff base bonds with the amino groups on the chitosan derivative. The amino groups on the molecular chain of the gel matrix form dynamic Schiff base bonds with the quinone groups on the silver tannic acid nanoparticles.

2. The injectable gel according to claim 1, characterized in that: The gel matrix contains chemical bonds and hydrogen bonds.

3. The injectable gel according to claim 1, characterized in that: The silver tannin nanoparticle content in the injectable gel is 0.1 mg / mL to 5 mg / mL.

4. The injectable gel according to claim 1, characterized in that: The mass ratio of the dopamine-grafted modified oxidized natural polymer and the chitosan derivative in the gel matrix is ​​1~10:

1.

5. The method for preparing the injectable gel according to any one of claims 1 to 4, characterized in that, The process includes the following steps: mixing silver tannin nanoparticles with a chitosan derivative solution to obtain a gel prepolymer solution, adding a dopamine-grafted modified oxidized natural polymer solution, and crosslinking to obtain the final product. The preparation method of the silver tannic acid nanoparticles includes: slowly adding AgNO3 solution dropwise to an aqueous solution of tannic acid with pH=9~10, reacting, and freeze-drying to obtain the nanoparticles. The preparation method of the dopamine-grafted modified oxidized natural polymer includes: adding dopamine solution dropwise to a mixed solution of oxidized natural polymer and 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, reacting in the absence of oxygen, dialyzing, and lyophilizing to obtain the product; The pH of the gel prepolymer solution is 8-10.

6. The use of the injectable gel according to any one of claims 1 to 4 in the preparation of a medicament for treating periodontitis.

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