Hydrogel with photo-thermal antibacterial and healing-promoting functions as well as preparation method and application of hydrogel

Abstract

The invention relates to the technical field of biomedical materials, in particular to photo-thermal antibacterial healing-promoting hydrogel as well as a preparation method and application thereof. The preparation method of the hydrogel comprises the following steps: dispersing mesoporous polydopamine (MPDA) into a Tris-HCl solution, and then adding L-arginine to prepare L-MPDA; the preparation method comprises the following steps: fully dissolving 3-(aminomethyl) phenylboronic acid hydrochloride and 4-(4, 6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride into hyaluronic acid (HA), regulating the pH value to 6.5 by using alkali liquor to obtain phenylboronic acid modified hyaluronic acid mixed liquor, and dialyzing and freeze-drying to obtain HA-PBA. The preparation method comprises the following steps: dissolving metformin and purified L-MPDA in deionized water, sequentially adding purified HA-PBA and a polyvinyl alcohol (PVA) solution, and uniformly mixing to obtain the hydrogel. The hydrogel prepared by the invention has excellent hemostasis, antibacterial and adhesion properties. When the hydrogel is used as a hydrogel dressing for treating a diabetic wound surface, the healing speed of the diabetic wound surface can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, and in particular to a hydrogel with photothermal antibacterial and healing-promoting properties, and a preparation method and application thereof. Background Art

[0002] Diabetes has become an increasingly serious health problem worldwide. In 2021, the proportion of diabetic patients in the global population aged 20-79 years old was approximately 10.5% (approximately 536.6 million), and it is expected to rise to approximately 12.2% (approximately 783.2 million) by 2045. Diabetic wounds are generally in a moist, high-sugar environment, which promotes the occurrence of bacterial proliferation, biofilm formation, and persistent inflammation at the wound surface, all of which seriously hinder the healing of wound surfaces. In addition, excessive oxidative stress and reactive oxygen species (ROS) in the wound microenvironment can cause damage to cell membranes, proteins, and DNA, disrupt angiogenesis and tissue regeneration, all of which will delay the healing process of diabetic wound surfaces. Although current treatments (such as blood sugar control, antibiotic treatment, and wound management) can promote the healing of diabetic wound surfaces, the increase in antibiotic resistance will greatly weaken the efficacy of the above treatments. Clinical reports have also used hydrogels containing cytokines, extracellular matrix components or extracellular vesicles to treat diabetic wounds, but the existing hydrogels have relatively poor hemostatic and antibacterial effects, which makes the wounds susceptible to infection and persistent inflammatory reactions, thereby delaying the healing of the wounds. Existing hydrogels have poor adhesion and are easy to rupture, which makes them prone to falling off and rupturing when applied to wounds in active areas such as joints, causing potential damage to the wounds. In addition, since the skin is rich in a large number of blood vessels, once damaged, bleeding is inevitable, so in the initial stage of wound healing, the wound needs to be hemostatically stopped in time, and the existing hydrogels have poor hemostatic effects, which will greatly delay the healing speed of the wound. Summary of the Invention

[0003] In order to solve the technical problem that the hemostatic, antibacterial and adhesive properties of hydrogels in the prior art are relatively poor, which greatly delays the healing process of diabetic wounds, the present invention provides a hydrogel with photothermal antibacterial and healing-promoting properties, as well as a preparation method and application thereof.

[0004] The present invention is implemented using the following technical solution: a method for preparing a hydrogel with photothermal antibacterial and healing-promoting properties, comprising the following steps: dispersing mesoporous polydopamine in a Tris-HCl solution with a pH of 8.5 in a certain proportion, then adding L-arginine in a mass ratio of 1:20 to the Tris-HCl solution to produce L-MPDA. 3-(Aminomethyl)phenylboronic acid hydrochloride and 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride in a mass ratio of 47:80 are fully dissolved in a hyaluronic acid solution, and the pH is adjusted to 6.5 with alkaline solution to produce a phenylboronic acid-modified hyaluronic acid mixture. The phenylboronic acid-modified hyaluronic acid mixture is dialyzed and freeze-dried to produce HA-PBA. Metformin and purified L-MPDA are dissolved in deionized water in a mass ratio of 2:1, and purified HA-PBA is added in a certain proportion to produce a mixture B. Then, a polyvinyl alcohol solution having a volume ratio of 1:1 to the mixed solution B was added and mixed evenly to prepare a hydrogel.

[0005] As a further improvement of the present invention, mesoporous polydopamine is obtained by a template method. The specific steps of preparing mesoporous polydopamine by the template method include: fully dispersing dopamine and Pluronic F-127 in an aqueous ethanol solution at a mass ratio of 3:2, then adding 1,3,5-trimethylbenzyl at a volume ratio of 8:25 to ethanol and ultrasonically dispersing the mixture to obtain an emulsion D. Ammonia aqueous solution at a volume ratio of 1:200 to 1:300 is added to the emulsion D while stirring, to obtain a mixed solution E. The coarse particles in the mixed solution E are collected by centrifugation, ultrasonically treated in an ethanol / acetone mixture at a volume ratio of 2:1, and then washed, centrifuged, and freeze-dried to obtain the mesoporous polydopamine.

[0006] In a typical technical solution of the present invention, the purification step of L-DMPA includes: collecting the obtained L-MMPA by centrifugation, washing and freeze-drying in sequence to obtain purified L-DMPA.

[0007] In a typical technical solution of the present invention, the purification step of HA-PBA includes: dialyzing and freeze-drying the obtained HA-PBA in sequence to obtain purified HA-PBA.

[0008] In a typical technical solution of the present invention, the dialysis operation uses a dialysis bag with a molecular cutoff value of 6-8 kDa, and the dialysis operation conditions are dialysis with deionized water at room temperature for 5 days, and the deionized water is replaced twice a day.

[0009] As a further improvement of the present invention, the preparation method of the polyvinyl alcohol solution is as follows: polyvinyl alcohol is dispersed in deionized water according to a proportion, and the polyvinyl alcohol is heated in a water bath at 95° C. until the polyvinyl alcohol is completely dissolved to obtain the PVA solution.

[0010] In a typical technical solution of the present invention, the concentration of L-MPDA is 0.25 mg / mL to 1.0 mg / mL.

[0011] In a typical technical solution of the present invention, the concentration of the hyaluronic acid solution is 5 mg / mL.

[0012] In a typical technical solution of the present invention, the concentration of metformin is 1.0 mg / mL.

[0013] In a typical technical solution of the present invention, the concentration of HA-PBA is 20 mg / mL.

[0014] In a typical technical solution of the present invention, the concentration of polyvinyl alcohol is 30 mg / mL.

[0015] The present invention also includes a hydrogel with photothermal antibacterial and healing-promoting effects, which is prepared using the above-mentioned preparation method. The prepared hydrogel can be combined with photothermal therapy to promote the healing of diabetic wounds.

[0016] The present invention also includes the use of the above-mentioned hydrogel with photothermal antibacterial and healing-promoting properties in the preparation of diabetic wound dressings.

[0017] The technical solution provided by the present invention has the following beneficial effects:

[0018] (1) The preparation method of the hydrogel with photothermal antibacterial and healing-promoting properties provided by the present invention is to modify mesoporous polydopamine with L-arginine and modify hyaluronic acid with phenylboronic acid, so that the prepared hydrogel has excellent hemostasis, antibacterial and adhesion properties. When it is used as a hydrogel dressing to treat diabetic wounds, it can effectively promote the healing of diabetic wounds and increase the healing speed of diabetic wounds. Among them, dopamine has a porous structure. In this embodiment, by modifying L-arginine to mesoporous polydopamine, the prepared hydrogel can simultaneously have the properties of mesoporous polydopamine and L-arginine. Among them, the cationic effect of L-arginine can kill bacteria, and it also has the effects of reducing oxidative stress and promoting vascularization, so that the prepared hydrogel has the properties of antibacterial, reducing oxidative stress, and promoting vascularization. At the same time, mesoporous polydopamine can convert laser energy into local heat, so that the prepared hydrogel can be used in combination with photothermal therapy. Photothermal therapy offers numerous therapeutic advantages, including precise targeting, deep penetration into tissues / biomembranes, minimal invasiveness, rapid action, and reduced side effects. It also enhances local blood circulation, promotes fibroblast proliferation and collagen synthesis, promotes tissue repair and regeneration, and accelerates wound healing. In this protocol, mesoporous polydopamine is modified with L-arginine, enabling the photothermal therapy of L-arginine and mesoporous polydopamine to synergistically exert antibacterial effects. Furthermore, by modifying hyaluronic acid with phenylboronic acid, the phenylboronic acid-modified hyaluronic acid forms a dynamic covalent bond, phenylboronic acid ester, with polyvinyl alcohol. The phenylboronic acid ester bond formed by these three raw materials enables the prepared hydrogel to restore its integrity after damage, extending the hydrogel's lifespan, reducing the frequency of replacement, and lowering the risk of secondary damage.

[0019] (2) The preparation method of the hydrogel with photothermal antibacterial and healing-promoting properties provided by the present invention is that the glucose sensitivity of the phenylboronic acid ester bond formed by it gives the hydrogel of this scheme glucose responsiveness. In an environment with high glucose concentration, glucose competes with polyvinyl alcohol for the binding sites on the phenylboronic acid group, which will lead to the breakage of some phenylboronic acid ester bonds. The breakage of the phenylboronic acid ester bond will destroy the cross-linking network of the hydrogel, causing the hydrogel to disintegrate, thereby allowing the metformin in the hydrogel to be released, so that the released metformin can be organically combined with the microenvironment of the diabetic infection wound, thereby achieving the purpose of clearing oxidative stress and reactive oxygen species, accelerating the healing rate of the diabetic infection wound, and at the same time, this release mechanism allows metformin to be released in the microenvironment of the diabetic infection wound, thereby improving the utilization rate of metformin.

[0020] (3) The hydrogel with photothermal antibacterial and healing-promoting properties provided by the present invention, when applied as a hydrogel dressing to diabetic wounds, can effectively provide antibacterial and antimicrobial properties, stop bleeding, and accelerate the healing rate of diabetic wounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart for preparing the hydrogel with photothermal antibacterial and healing-promoting properties provided by the present invention.

[0022] Figure 2 These are actual pictures of the inversion experiments performed on the hydrogels in Examples 2 to 7 of the present invention.

[0023] Figure 3 This is a picture of the hydrogel prepared in Example 2 of the present invention taken under a scanning electron microscope.

[0024] Figure 4 Graph showing the change in swelling ratio over time of the hydrogels of Examples 2, 3 and 6 of the present invention.

[0025] Figure 5 Graph showing the residual mass ratio of the hydrogels of Examples 2, 3 and 6 of the present invention changing with time.

[0026] Figure 6 This is a graph showing the change in the ratio of the cumulative release of metformin to the total amount of metformin in the hydrogel of Example 2 of the present invention in two groups of centrifuge tubes with different components over time.

[0027] Figure 7 This is a photo of the hydrogel prepared in Example 2 of the present invention being extruded through a 16G syringe needle.

[0028] Figure 8 Schematic diagram of the process of conducting self-healing experiments on the hydrogel of Example 2 of the present invention.

[0029] Figure 9 These are actual pictures of the adhesion experiment of the hydrogel of Example 2 of the present invention to different materials.

[0030] Figure 10 These are experimental pictures of the hydrogel according to Example 2 of the present invention adhering to pig skin and undergoing repeated bending and twisting.

[0031] Figure 11 This is a picture of the hydrogel of Example 2 of the present invention being tested using a universal material testing machine.

[0032] Figure 12 4 is a bar graph showing the bonding strength of Examples 3, 4 and 6 of the present invention.

[0033] Figure 13 These are actual pictures of the hemostatic effects of Example 3, Example 6, Example 2 of the present invention, as well as gauze and a control group not covered with anything, on rat tail wounds.

[0034] Figure 14The 808nm near-infrared laser with a power of 0.5W / cm 2 Thermal images of the hydrogels of different examples after irradiation with an intensity of 10 min.

[0035] Figure 15 The hydrogels of different embodiments were irradiated with 808 nm near-infrared laser at 0.5 W / cm 2 A graph showing the temperature change over time when the intensity is irradiated for 10 minutes.

[0036] Figure 16 4 is a graph showing the temperature and time changes of the hydrogel in Example 6 of the present invention when it undergoes multiple periodic near-infrared switches.

[0037] Figure 17 3 and 4 are histograms of cell viability of Example 3, Example 6, Example 2 and the anhydrous gel group on the first, second and third days of the present invention.

[0038] Figure 18 The figures are experimental pictures of blood compatibility of different embodiments of the present invention and a bar graph of hemolysis rate of different embodiments.

[0039] Figure 19 These are pictures taken at different time points of the wound surface when the hydrogels according to different embodiments of the present invention are used to repair diabetic infection wounds.

[0040] Figure 20 This is a graph showing the relationship between the wound healing rate and time of the rat back wounds after being treated with hydrogels according to different embodiments of the present invention.

[0041] Figure 21 These are actual pictures of the colony counts of Staphylococcus aureus on five groups of agar plates of the present invention.

[0042] Figure 22 The figure is a bar graph showing the survival rate of Staphylococcus aureus colonies on five groups of agar plates. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] Example 1

[0045] This embodiment provides a method for preparing a hydrogel with photothermal antibacterial and healing promoting properties. Figure 1 , which includes the following steps:

[0046] (1) Modification of L-arginine onto mesoporous polydopamine (MPDA)

[0047] Step 1: First, mesoporous polydopamine can be prepared using a template method. This method involves thoroughly dispersing dopamine and Pluronic F-127 in a 50% ethanol-water solution at a mass ratio of 3:2 and stirring at room temperature. Then, 1,3,5-trimethylphenyl is added at a volume ratio of 8:25 to ethanol and ultrasonically dispersed under heating to obtain emulsion D. Subsequently, while stirring, ammonia solution at a volume ratio of 1:200-1:300 is rapidly added to emulsion D to obtain mixed solution E. After reacting for 2 hours at room temperature, the coarse particles in mixed solution E are collected by centrifugation and ultrasonically treated in a 2:1 ethanol / acetone mixture to remove the template. The mesoporous polydopamine is then obtained by washing, centrifugation, and freeze-drying.

[0048] Step 2: Modify L-arginine onto mesoporous polydopamine. The specific steps include: dispersing mesoporous polydopamine in a Tris-HCl solution with a pH of 8.5, and then ultrasonically dispersing it in a water bath until the mesoporous polydopamine is evenly dispersed in the Tris-HCl solution. Then, L-arginine is dissolved in the Tris-HCl solution at a mass ratio of 1:20 to mesoporous polydopamine, and L-MPDA is obtained after stirring at room temperature. Mesoporous polydopamine has a porous structure. In this embodiment, by modifying L-arginine onto mesoporous polydopamine, the prepared hydrogel can simultaneously possess the properties of mesoporous polydopamine and L-arginine. The cationic effect of L-arginine can kill bacteria, and it also has the effects of reducing oxidative stress and promoting vascularization, so that the prepared hydrogel has the properties of antibacterial, reducing oxidative stress, and promoting vascularization. At the same time, mesoporous polydopamine can convert laser energy into local heat, so that the prepared hydrogel can be used in combination with photothermal therapy. Photothermal therapy offers numerous therapeutic advantages, including precise targeting, deep penetration into tissues / biomembranes, minimal invasiveness, rapid action, and reduced side effects. It also enhances local blood circulation, promotes fibroblast proliferation and collagen synthesis, promotes tissue repair and regeneration, and accelerates wound healing. In this protocol, mesoporous polydopamine is modified with L-arginine, enabling the synergistic antibacterial effects of L-arginine and mesoporous polydopamine photothermal therapy.

[0049] Among them, L-arginine can be modified onto mesoporous polydopamine through the following two mechanisms when coupled with mesoporous polydopamine. The first is electrostatic attraction. When L-arginine is dispersed in a Tris-HCl solution, the L-arginine molecule will be positively charged, so the positively charged L-arginine can be adsorbed onto the negatively charged surface of mesoporous polydopamine. The second is covalent interaction. Ligands with nucleophilic functional groups (such as the amino group in L-arginine) can react with mesoporous polydopamine under alkaline conditions, thereby achieving the modification of L-arginine onto mesoporous polydopamine.

[0050] Step 3: Purify L-MPDA. The purification step includes: collecting the obtained L-MPDA by centrifugation, washing it with deionized water multiple times, and finally freeze-drying it to obtain purified L-MPDA.

[0051] (2) Modification of hyaluronic acid (HA) with phenylboronic acid

[0052] Hyaluronic acid was dispersed in deionized water at a ratio of 5 mg hyaluronic acid to 1 mL. Stirring was continued at room temperature until the hyaluronic acid was completely dissolved in the deionized water, yielding a hyaluronic acid solution. 3-(Aminomethyl)phenylboronic acid hydrochloride and 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride were then dissolved in the hyaluronic acid solution at a mass ratio of 47:80. The pH was adjusted to 6.5 with alkali solution and stirred at room temperature for 72 hours to yield a phenylboronic acid-modified hyaluronic acid mixture. The phenylboronic acid-modified hyaluronic acid mixture was dialyzed and freeze-dried to yield HA-PBA. Hyaluronic acid, polyvinyl alcohol, and mesoporous polydopamine all exhibited certain adhesive properties. The addition of L-arginine enhanced the adhesive properties of the mesoporous polydopamine. The synergistic effect of these components resulted in the resulting hydrogel exhibiting excellent adhesive properties.

[0053] In this embodiment, the main function of 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride is to act as an efficient condensing agent, which can promote the chemical reaction between PBA and HA, thereby improving the modification efficiency of phenylboronic acid-modified hyaluronic acid. It can be understood that the mechanism by which 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride promotes the chemical reaction between phenylboronic acid and hyaluronic acid is as follows: (I) 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride can activate the carboxyl group in hyaluronic acid to form an intermediate (such as an acyl imidazole analogue), thereby accelerating the reaction rate between phenylboronic acid and hyaluronic acid. (II) The boronic acid group in phenylboronic acid reacts with the carboxyl group of the activated hyaluronic acid to form an ester bond or other covalent bond. (III) Phenylboronic acid reacts directly with the hydroxyl groups in hyaluronic acid, while 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride can improve the reaction efficiency between phenylboronic acid and hyaluronic acid by stabilizing the transition state.

[0054] Wherein, in the present embodiment, the hyaluronic acid mixed solution after phenylboronic acid modification can be dialyzed using a dialysis bag with a molecular weight cutoff of 6-8kDa. The specific operation of dialysis is as follows: the hyaluronic acid mixed solution modified by phenylboronic acid is transferred to a dialysis bag with a molecular weight cutoff of 6-8kDa, and dialyzed with deionized water for 5 days at room temperature, with water changed twice a day. The effect of dialysis is to remove unreacted phenylboronic acid, condensing agent by-products and buffer components, eliminate salt ions and pH regulator residues, thereby obtaining a high-purity, low-toxicity product, so that the product obtained meets the needs of biomedicine.

[0055] In this protocol, sodium hydroxide solution can be used to adjust the pH of the hyaluronic acid solution containing 3-(aminomethyl)phenylboronic acid hydrochloride and 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride. The pH is adjusted to 6.5 because phenylboronic acid is most reactive at this pH, facilitating the formation of stable borate ester bonds with the hydroxyl groups of hyaluronic acid.

[0056] (3) Preparation of hydrogel

[0057] Metformin and purified L-MPDA were dissolved in deionized water at a mass ratio of 2:1, and purified HA-PBA was added in proportion to obtain a mixed solution B. A polyvinyl alcohol (PVA) solution was then added to the mixed solution B at a volume ratio of 1:1 to the mixed solution B and mixed thoroughly to obtain a hydrogel.

[0058] It is understandable that the raw materials used to prepare the hydrogel in this solution are widely available and inexpensive, and its preparation process is relatively simple, so the cost of preparing the hydrogel can be greatly reduced. In this solution, hyaluronic acid is modified with phenylboronic acid, so that the hyaluronic acid modified with phenylboronic acid can form a dynamic covalent bond, a phenylboronic acid ester bond, with polyvinyl alcohol. The phenylboronic acid ester bond formed by these three raw materials can restore the integrity of the prepared hydrogel after damage, extend the service life of the hydrogel, reduce the frequency of replacement, and reduce the risk of secondary injury. Metformin can relieve inflammation and oxidative stress, promote the production of fibroblasts and the formation of granulation tissue, thereby accelerating wound healing. However, metformin in the prior art is easily degraded and inactivated in diabetic wounds, making it difficult to maintain long-term biological activity. The hydrogel in this embodiment, due to the glucose sensitivity of the phenylboronic acid ester bond formed, gives the hydrogel of this solution glucose responsiveness. In an environment with high glucose concentration, glucose competes with polyvinyl alcohol for binding sites on the phenylboronic acid group, which will lead to the breakage of some phenylboronic acid ester bonds. The breaking of the phenylboronic acid ester bond will destroy the cross-linking network of the hydrogel, causing the hydrogel to disintegrate, thereby releasing the metformin in the hydrogel. The released metformin can then organically combine with the microenvironment of the diabetic wound, thereby achieving the purpose of clearing oxidative stress and reactive oxygen species and accelerating the healing rate of the diabetic wound. At the same time, this release mechanism enables metformin to be released specifically in the microenvironment of the diabetic wound, thereby improving the utilization rate of metformin.

[0059] The mesoporous polydopamine in this solution can convert laser energy into local heat, and this photothermal property of mesoporous polydopamine is adjustable and photostable. Therefore, in practical applications, we can use the hydrogel prepared in this solution in combination with photothermal therapy. In addition, since photothermal therapy can enhance local blood circulation, promote fibroblast proliferation and collagen synthesis, promote tissue repair and regeneration, and accelerate wound healing. Therefore, in practical applications, by combining hydrogels with photothermal therapy, pathogens can be effectively removed physically, thereby increasing the speed of healing of diabetic wounds. In addition, the cationic effect of L-arginine can kill bacteria, and it also has the effects of reducing oxidative stress and promoting vascularization. Therefore, in this embodiment, mesoporous polydopamine is modified with L-arginine, and combined with the photothermal properties of mesoporous polydopamine itself, the prepared hydrogel can synergistically exert an antibacterial effect under the photothermal properties of L-arginine and mesoporous polydopamine, thereby greatly improving the antibacterial effect of the hydrogel in this embodiment. At the same time, since the hydrogel contains L-arginine, it can reduce oxidative stress and promote vascularization. In combination with the released metformin, it can effectively improve the healing speed of diabetic wounds.

[0060] Example 2

[0061] Based on Example 1, this embodiment provides a specific method for preparing a hydrogel with photothermal antibacterial and healing-promoting properties, which includes the following steps: (1) dispersing 1.5 g dopamine and 1.0 g Pluronic F-127 in 100 mL of ethanol-water solution and stirring at room temperature for 10 minutes. The ethanol in the ethanol-water solution is 50 mL and the water is 50 mL. Then, 1.6 mL of 1,3,5-trimethylbenzene (TMB) is added and ultrasonically dispersed in a water bath for 2 minutes to gradually form an emulsion. Subsequently, 3.75 mL of ammonia solution is quickly added under stirring conditions. After reacting at room temperature for 2 hours, the coarse particles in the emulsion with ammonia solution are centrifuged. The collected coarse particles are ultrasonically treated in an ethanol / acetone mixture to remove the template and washed with deionized water several times. The volume ratio of ethanol to acetone in the ethanol / acetone mixture is 2:1. Finally, the product after washing with deionized water is centrifuged and freeze-dried to obtain mesoporous polydopamine. The prepared mesoporous polydopamine was then dispersed in a Tris-HCl solution with a pH of 8.5, and then ultrasonically dispersed in a water bath for 2 minutes. L-arginine at a concentration of 20 mg / mL was then dissolved in the Tris-HCl solution and stirred at room temperature for 12 hours to obtain L-arginine-modified mesoporous polydopamine, namely L-MPDA. The obtained L-MPDA was then collected by centrifugation and washed with deionized water several times, and finally freeze-dried to obtain purified L-MPDA. (2) 400 mg of hyaluronic acid was dispersed in 80 mL of deionized water and stirred continuously at room temperature until completely dissolved to obtain a hyaluronic acid solution. Then 188 mg of 3-(aminomethyl)phenylboronic acid hydrochloride and 320 mg of 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride were added to the hyaluronic acid solution respectively, and stirred continuously until completely dissolved. The solution pH was then adjusted to 6.5 with 1 mol / L NaOH and stirred at room temperature for 72 hours to obtain HA-PBA. Then, HA-PBA was transferred to a dialysis bag with a molecular weight cutoff (MWCO) of 6-8 kDa and dialyzed with deionized water at room temperature for 5 days, with the water changed twice a day. Finally, the dialysate was freeze-dried to obtain purified HA-PBA. (3) 300 mg of polyvinyl alcohol was dispersed in 10 mL of deionized water and heated in a water bath at 95°C until completely dissolved to obtain a polyvinyl alcohol solution with a concentration of 30 mg / mL. 10 mg of metformin and 5 mg of purified L-MPDA were dissolved in 10 mL of deionized water, and 200 mg of purified HA-PBA was added. After continuous shaking, a mixture B was obtained.Then, a polyvinyl alcohol solution with a concentration of 30 mg / mL and a volume ratio of 1:1 to the mixed solution B was added, and the mixture was mixed evenly to obtain a hydrogel (i.e., Met / L-MPDA / Gel). The concentration of L-MPDA in the hydrogel (Met / L-MPDA / Gel) was 0.5 mg / mL.

[0062] Example 3

[0063] Dissolve 200 mg of purified HA-PBA in 10 mL of deionized water to prepare an HA-PBA solution. Disperse 300 mg of polyvinyl alcohol in 10 mL of deionized water and heat in a water bath at 95°C until completely dissolved to prepare a polyvinyl alcohol solution. Mix the prepared HA-PBA solution and polyvinyl alcohol solution in a 1:1 volume ratio and shake continuously to prepare a gel.

[0064] Example 4

[0065] Disperse 300 mg of polyvinyl alcohol in 10 mL of deionized water and heat in a water bath at 95°C until completely dissolved to prepare a polyvinyl alcohol solution, which is set aside. Dissolve 5 mg of mesoporous polydopamine in 10 mL of deionized water. Once completely dissolved, add 200 mg of purified HA-PBA and mix thoroughly to obtain Mixture 1. Add the polyvinyl alcohol solution to Mixture 1 at a 1:1 volume ratio and shake continuously to prepare MPDA / Gel.

[0066] Example 5

[0067] Disperse 300 mg of polyvinyl alcohol in 10 mL of deionized water and heat in a water bath at 95°C until completely dissolved to prepare a polyvinyl alcohol solution, which is set aside. Dissolve 2.5 mg of purified L-MPDA in 10 mL of deionized water, mix thoroughly, then add 200 mg of purified HA-PBA and shake well to obtain a second mixture. Add the polyvinyl alcohol solution to the first mixture at a 1:1 volume ratio and shake well to obtain a 0.25 mg / mL L-MPDA / Gel.

[0068] Example 6

[0069] Disperse 300 mg of polyvinyl alcohol in 10 mL of deionized water and heat in a water bath at 95°C until completely dissolved to prepare a polyvinyl alcohol solution, which is set aside. Dissolve 5 mg of purified L-MPDA in 10 mL of deionized water, mix thoroughly, then add 200 mg of purified HA-PBA and shake continuously to obtain a second mixture. Add the polyvinyl alcohol solution to the first mixture at a 1:1 volume ratio and shake continuously to obtain a 0.5 mg / mL L-MPDA / Gel.

[0070] Example 7

[0071] Disperse 300 mg of polyvinyl alcohol in 10 mL of deionized water and heat in a water bath at 95°C until completely dissolved to prepare a polyvinyl alcohol solution, which is set aside. Dissolve 10 mg of purified L-MPDA in 10 mL of deionized water, mix thoroughly, then add 200 mg of purified HA-PBA and shake well to obtain a second mixture. Add the polyvinyl alcohol solution to the first mixture at a 1:1 volume ratio and shake well to prepare a 1 mg / mL L-MPDA / Gel.

[0072] Example 8

[0073] Based on Example 2, this example provides an application of a hydrogel with photothermal antibacterial and healing-promoting properties, which can be used to prepare a diabetic wound dressing.

[0074] Performance Testing

[0075] In order to verify the performance of the hydrogel with photothermal antibacterial and healing-promoting properties provided in this embodiment, the applicant also conducted the following experiments to verify.

[0076] (1) Inversion experiment

[0077] The hydrogels of different components prepared in Examples 2 to 7 were placed in test tubes respectively, and the test tubes were inverted to obtain the following Figure 2 Picture shown. Figure 2 The macroscopic morphology photos of hydrogels with different components. Figure 2 It can be seen from the inversion experiment that hydrogels of different components are successfully prepared by the preparation method in this scheme, and these hydrogels of different components show different colors.

[0078] (2) Scanning electron microscopy experiment

[0079] The hydrogel prepared in Example 2 was freeze-dried, and then immersed in liquid nitrogen to obtain a brittle fracture sample. The sample was then sputtered with gold, and its surface morphology was examined using a scanning electron microscope, as shown in FIG. Figure 3 Picture shown. Figure 3 This is a picture of the hydrogel prepared in Example 2 taken under a scanning electron microscope. Figure 3 It can be seen that the hydrogel prepared in Example 2 has an obvious porous structure, the surface of the hydrogel is rough, and L-MPDA is evenly distributed throughout the hydrogel matrix.

[0080] (3) Swelling test

[0081] The swelling properties of the hydrogels prepared in Example 2, Example 3 and Example 6 were measured by weight method. The operation of the swelling experiment is as follows: the completely gelled hydrogel is placed in a test tube with a pH of 7.4 and containing 20 mL of PBS, and shaken at 37°C and 100 rpm. The hydrogel is removed at different time points, and the surface moisture is absorbed with filter paper and the hydrogel is weighed again. Among them, the swelling rate calculation formula is: (Wt-Wi) / Wi×100%, where Wi is the initial dry weight of the hydrogel, and Wt is the weight of the hydrogel after swelling. By obtaining the weight of the hydrogel after swelling at different time points and using the swelling rate calculation formula, a curve graph of the swelling rate changing with time can be obtained. By performing the above operations on Example 2, Example 3 and Example 6 respectively, a curve graph of the swelling rate of the hydrogels of different components changing with time can be obtained, that is Figure 4 Through Figure 4 Analysis revealed that the hydrogels in Examples 2, 3, and 6 all absorbed approximately twice their own weight. This demonstrates that all hydrogels possessed excellent water absorption capacity. The equilibrium swelling ratios of Examples 2 and 6 were slightly lower than that of Example 3, suggesting crosslinking between L-MPDA and Gel. Swelling experiments confirmed that all hydrogels exhibited excellent water absorption, demonstrating their ability to effectively absorb tissue exudate while maintaining a moist wound environment.

[0082] (IV) Degradation experiment

[0083] The degradation experiment is performed as follows: the prepared hydrogels are freeze-dried and then weighed, and their mass is calculated as W1. The freeze-dried hydrogels are then completely immersed in test tubes with a pH of 7.4 and containing 20 mL of PBS, and shaken at 37°C and 100 rpm. The hydrogels are taken out at different time points, freeze-dried, and then weighed as W2. The calculation formula for the residual mass ratio is: W2 / W1×100%. The larger the residual mass ratio, the smaller the degradation rate of the hydrogel of this component. By carrying out Example 2, Example 3 and Example 6 according to the above-mentioned degradation experiment, a curve graph showing the change of the residual mass ratio of the hydrogels of different components over time can be obtained, that is, Figure 5 Through Figure 5 Analysis revealed that over time, the residual mass ratios of all three hydrogel groups approached a plateau around day 14, and the residual mass percentages for all three groups were below 30%, demonstrating that all three groups exhibited excellent degradation properties. This excellent degradation performance is crucial for the biomedical applications of hydrogels. Furthermore, the time to plateau degradation closely coincided with wound healing, making all three groups suitable for use as wound dressings. The hydrogel in Example 2 exhibited the lowest residual mass percentage, demonstrating that the hydrogel in Example 2 exhibited the best degradation performance and met current degradation requirements for wound dressings.

[0084] (5) Metformin release experiment

[0085] The metformin release experiment was performed as follows: First, two 15 mL centrifuge tubes were prepared, and 200 μL of Met / L-MPDA / Gel was prepared in each centrifuge tube. A PBS solution with a pH of 7.4 and a volume of 10 mL was added to one of the centrifuge tubes, and a PBS solution with a pH of 7.4 and a volume of 10 mL containing 4 g / L glucose was added to the other centrifuge tube. The two centrifuge tubes were then placed in a shaker at 37°C and 100 rpm and shaken evenly. 1 mL of release liquid was taken from the centrifuge tube at different time points for further analysis. 1 mL of fresh buffer was then added to the test tube to maintain a constant volume. Finally, the drug release of the hydrogels in the two centrifuge tubes was analyzed using a UV-visible spectrophotometer. The formula for calculating the ratio of the cumulative release of metformin to the total amount of metformin in the sample is: (10C n +∑C n-1 ) / M0×100%, where “C n ” is the concentration of metformin in the release medium after extraction for the nth time (mg / mL); “C n-1 " is the concentration of metformin in the release medium at the time of extraction (n-1) (mg / mL); n is the extraction time of the release medium, and M0 is the content of metformin in the sample (in mg). By calculating the cumulative release of metformin in the two groups of centrifuge tubes at different time points, a curve of the ratio of the cumulative release of metformin in the two groups of centrifuge tubes to the total amount of metformin in the sample over time can be obtained, that is, Figure 6 Through Figure 6 Analysis showed that after 7 days of drug release experiments, the cumulative release of metformin in the glucose-containing group was significantly higher than that in the glucose-free group. This suggests that the hydrogel of Example 2 can effectively address the prior art issue of diabetic wounds being difficult to heal due to hyperglycemia. By loading metformin onto the hydrogel dressing, it can achieve intelligent metformin release and improve metformin utilization. Furthermore, the other raw liquids in the hydrogel possess excellent antibacterial, hemostatic, and adhesive properties, enabling the hydrogel to accelerate the healing rate of diabetic wounds.

[0086] (6) Injectability, self-healing and adhesion of hydrogels

[0087] 6.1 Injectability of hydrogels

[0088] The injectability of the hydrogel prepared in Example 2 was evaluated by extrusion using a 16G syringe needle. Figure 7 .pass Figure 7As can be seen, the hydrogel prepared in Example 2 exhibits excellent injectability, being easily extruded through a 16G syringe needle while maintaining its structural integrity after extrusion, allowing it to be extruded into the desired shape upon injection. This advantage is primarily due to the shear-thinning properties of the hydrogel in Example 2, which temporarily reduces its viscosity under shear stress, facilitating smooth extrusion of the hydrogel. Furthermore, the hydrogel quickly recovers its structure and viscosity after extrusion.

[0089] 6.2 Self-healing properties of hydrogels

[0090] In order to evaluate the self-healing properties of the hydrogel, we cut the hydrogel of Example 2 into two sections and placed them in contact at room temperature for 1 minute. We observed the recovery of the hydrogel and then pulled the two sections apart to evaluate their self-healing properties. Figure 8 As shown. Figure 8 It can be seen that the hydrogel cut into two sections fully recovered after one minute of contact without external stimulation. Even after recovery, the recovered hydrogel remained intact even when stretched to both sides. This proves that the hydrogel prepared in Example 2 has rapid self-healing ability. The remarkable self-healing properties of hydrogels are crucial for maintaining structural integrity in dynamic environments, especially in joint areas susceptible to mechanical stress (such as ankles and wrists).

[0091] 6.3 Adhesion of hydrogels

[0092] In order to evaluate the adhesion performance of the hydrogel prepared in Example 2, the applicant studied the adhesion performance of the hydrogel from the following aspects. First, the adhesion performance of the hydrogel prepared in Example 2 to human fingers, pig skin, plastic, glass, metal and pig internal organs was observed, and the following results were obtained: Figure 9 The results are shown. Figure 9 It can be seen that the hydrogel prepared in Example 2 exhibits strong adhesion to both biological tissues (such as heart, liver, spleen, lung, kidney, and skin) and non-biological materials (plastic, glass, and metal). Furthermore, the applicant also studied the adhesion properties of the hydrogel prepared in Example 2 to human skin tissue. The specific operation is as follows: First, fresh pig skin is selected to simulate human skin tissue and cut into 30×10 mm 2 The prepared hydrogel sample was coated on the pig skin surface with 100 mg of the prepared hydrogel sample, and the pig skin was repeatedly bent and twisted to obtain the following: Figure 10 The results shown by Figure 10It can be seen that after the hydrogel prepared in Example 2 adheres to the pigskin, even after repeated bending and twisting of the pigskin, the hydrogel still adheres firmly to the pigskin, showing strong adhesion under mechanical deformation. The results show that the prepared hydrogel can be effectively used as a wound dressing, maintaining stable adhesion to the wound site without falling off. Finally, the applicant also used a lap shear test to evaluate the adhesion performance of the hydrogel. The lap shear test is as follows: the pigskin is cut into two 30×10mm 2 The prepared hydrogel sample was then coated on one side of the pigskin surface with 100 mg of the prepared hydrogel sample and another piece of pigskin was placed on top of it to form a 10 × 10 mm rectangle. 2 After incubating at room temperature for 1 hour, the adhesion strength was measured using a universal material testing machine. Figure 11 .in Figure 11 The above lap shear test was performed on the hydrogels prepared in Example 3, Example 4 and Example 6 respectively, and the results were as follows: Figure 12 . Figure 12 The bar graph shows the bonding strength of Example 3, Example 4, and Example 6. The difference between Example 6 and Example 2 is that the hydrogel prepared in Example 2 contains metformin, which has no effect on the adhesion of the hydrogel. It is mainly used as a release drug for the treatment of diabetes to treat diabetic wounds. Therefore, in this experiment, the bonding strength of the hydrogel in Example 2 is the same as that of the hydrogel prepared in Example 6. Figure 12As can be seen, the bonding strength of the hydrogel in Example 3 is 14.67±1.08kPa, the bonding strength of the hydrogel in Example 4 is 18.77±0.98kPa, and the bonding strength of Example 6 is 22.11±1.53kPa, while the bonding strength of commonly used commercial hydrogels is generally 5kPa. It can be seen from this that the bonding strength of the hydrogels prepared in Examples 3, 4, and 6 is significantly higher than that of commonly used commercial hydrogels. Among them, for the bonding strength of the hydrogel in Example 3, its main raw materials are HA-PBA and polyvinyl alcohol. Since hyaluronic acid and polyvinyl alcohol both have adhesive properties, the bonding strength of the hydrogel prepared in Example 3 is higher than that of commonly used commercial hydrogels. The bonding strength of the hydrogel in Example 4 is greater than that of the hydrogel in Example 3. This is because the mesoporous polydopamine in Example 4 forms a physicochemical interaction with the pigskin (such as hydrogen bonds and Schiff base bonds), which results in the bonding strength of the hydrogel in Example 4 being greater than that of the hydrogel in Example 3. The hydrogel of Example 6 has the greatest adhesion strength, which is mainly because the hyaluronic acid, polyvinyl alcohol and mesoporous polydopamine in Example 6 all have certain adhesion properties, and the mesoporous polydopamine in Example 6 is also modified by L-arginine. By introducing L-arginine, the adhesion of the mesoporous polydopamine can be further enhanced, so that under the synergistic effect of these components, the hydrogel of Example 6 has excellent adhesion properties.

[0093] (VII) Hemostatic properties of hydrogels

[0094] The rat tail truncation model was used to evaluate the hemostatic properties of the hydrogel, and the operation was as follows: 5 rats of the same body size, age, and state characteristics were selected, and after anesthesia, the tails were truncation at the midpoint. The wound on the tail of the first rat was not covered with anything as the control group, the wound on the tail of the second rat was covered with gauze; the wound on the tail of the third rat was covered with the hydrogel of Example 3; the wound on the tail of the fourth rat was covered with the hydrogel of Example 6; and the wound on the tail of the fifth rat was covered with the hydrogel of Example 2. The bleeding conditions of the wounds on the tails of the five rats were then observed, and the following results were obtained: Figure 13 .pass Figure 13It can be seen that the amount of bleeding at the wound surface of the first rat's tail is the largest, and the amount of bleeding at the wound surface of the fourth and fifth rat's tail is the smallest, and the hemostasis time is the shortest. It can be seen that the wound surface of the rat's tail is all certain to hemostatic effect using gauze and various hydrogels, but the amount of blood loss and the shortest hemostasis time of the hydrogel of Example 6 and Example 3 are the least, and the hemostatic effect is the best. This is mainly because the hydrogel can be quickly attached to the bleeding tissue surface, forming a layer of physical barrier, which can directly block the wound and prevent blood from flowing out. Thus, the purpose of hemostasis is achieved. Secondly, hydrogel usually contains functional groups (such as hydrogen bonds, Schiff base bonds, etc.) that can interact strongly with tissue (such as proteins, cells, etc.), and these functional groups enable hydrogel to adhere firmly to moist, dynamic tissue surfaces. Even under blood flow impact, hydrogel will not fall off, thus maintaining its hemostatic effect. Furthermore, the porous structure of the mesoporous polydopamine in the hydrogel in this solution provides a reaction platform for coagulation factors (such as fibrinogen and thrombin), promoting the occurrence of the coagulation cascade and accelerating blood clot formation. Finally, the hydrogel is highly absorbent, allowing it to quickly absorb water from the blood at the wound site, causing the blood to concentrate, thereby increasing the concentration of platelets and coagulation factors at the wound site, thereby accelerating the coagulation process.

[0095] (8) Photothermal properties of hydrogels

[0096] The photothermal performance of the hydrogel was evaluated using an 808nm near-infrared laser (NIR). The specific operation was as follows: 6 test tubes were selected. A certain volume of PBS solution was placed in the first test tube as a control. An equal volume of the hydrogel prepared in Example 3 was placed in the second test tube; an equal volume of the hydrogel prepared in Example 4 was placed in the third test tube; an equal volume of the hydrogel prepared in Example 5 was placed in the fourth test tube; an equal volume of the hydrogel prepared in Example 6 was placed in the fifth test tube; and an equal volume of the hydrogel prepared in Example 7 was placed in the sixth test tube. All samples were then subjected to 808nm NIR at 0.5W / cm 2 The intensity of the radiation was irradiated for 10 minutes. The temperature change was recorded in real time using a thermal imager, and a thermal image was collected every 2 minutes. Finally, the NIR radiation at 808 nm was used at 0.5 W / cm 2 The intensity of 4 consecutive switching cycles, thus obtaining Figures 14 to 16 .

[0097] in, Figure 14 808nm near-infrared laser with 0.5W / cm 2 Thermal images of different samples after irradiation with the same intensity for 10 minutes. Figure 15 For different samples, 808 nm near-infrared laser was used at 0.5 W / cm 2 The temperature changes with time when the intensity of irradiation is 10 minutes. Figure 14 and Figure 15 Combined analysis shows that the temperature of the hydrogels in the control group and Example 3 barely changes with the extension of near-infrared laser irradiation time, which indicates that the PBS solution in the control group and the hydrogel in Example 3 have no photothermal properties. The temperature of the hydrogels in Examples 4, 5, 6 and 7 increases significantly with the extension of near-infrared laser irradiation time. Figure 15 Analysis shows that in Examples 5 to 7, as the amount of L-MPDA added increases, the rate of temperature increase increases. Therefore, in actual application, when preparing hydrogel dressings, we can select the appropriate proportion of L-MPDA according to the temperature requirements of the actual application scenario of the hydrogel dressing, so that the hydrogel dressing in this scheme can be applied to different scenarios, thereby improving its practicality. Among them, for L-MPDA with a concentration of 0.5 mg / mL, the temperature reaches 49.9°C after 10 minutes of near-infrared laser irradiation. This moderate temperature can not only effectively kill bacteria, but also reduce the necrosis of normal cells, meeting the basic biosafety requirements of mild antibacterial photothermal biomaterials. Therefore, in actual application, L-MPDA with a concentration of 0.5 mg / mL can be selected as the raw material for mild antibacterial photothermal hydrogel dressings.

[0098] Figure 16 The graph of the temperature and time variation of the hydrogel in Example 6 when it undergoes multiple periodic near-infrared switches is shown in FIG. Figure 16 Analysis shows that the temperature of the hydrogel in Example 6 hardly drops after four cycles of near-infrared switching, which indicates that the hydrogel in Example 6 has excellent photostability.

[0099] Furthermore, combined Figures 14 to 16 A comprehensive analysis shows that this scheme found that the temperature of the hydrogels in Examples 4 to 7 can gradually increase with the extension of the irradiation time through near-infrared laser irradiation, which proves that the hydrogels in Examples 4 to 7 in this scheme have photothermal properties. Therefore, in actual application, the hydrogels can be used in combination with photothermal therapy. The photothermal properties of the hydrogel can be exerted through near-infrared laser irradiation, and the photothermal properties of the hydrogel are adjustable and photostable.

[0100] (IX) Biocompatibility of hydrogels

[0101] In this scheme, L929 cells are used to evaluate the cytotoxicity of hydrogels. The specific operation can be as follows: L929 cells are seeded in a 96-well plate with a density of 5000 cells per well, and cultured for 24 hours to allow the cells to fully adhere. Subsequently, 100 μL of hydrogel extract is added to each well, and the cells are incubated with the hydrogel extract for 1, 2, and 3 days. After co-incubation, the cells are stained with a CCK-8 kit. The optical density (OD) value at 450 nm is then measured using a microplate reader. In this embodiment, the viability of L929 cells can be calculated using a sample group, a negative control group, and a blank control group. The sample group can select any one of the hydrogel or hydrogel-free groups in Examples 2 to 7. The negative control group is L929 cells, culture medium, and CCK-8 working solution; the blank control group is culture medium and CCK-8 working solution. Specifically, the calculation formula for cell viability is: (OD S -OD B ) / (OD N -OD B )×100%; where OD S OD is the optical density of the sample group at a wavelength of 450 nm; B OD is the optical density of the blank control group at a wavelength of 450 nm; N is the optical density value of the negative control group at a wavelength of 450 nm.

[0102] In this experiment, the following four groups of samples were selected: Example 3, Example 6, Example 2 and the no-hydrogel group to conduct cytotoxicity experiments on the hydrogels. Figure 17 data. Figure 17 The bar graphs show the cell viability of different sample groups on the first, second and third days. Figure 17 Analysis shows that Figure 17 The cell viability of all sample groups exceeded 90%, indicating that the cytotoxicity of the hydrogels prepared in these sample groups was very low. Therefore, it can be proved that the hydrogels prepared in the above examples all had excellent biocompatibility.

[0103] (10) Blood compatibility of hydrogel

[0104] In this scheme, the applicant also studied the blood compatibility of the hydrogel. The specific operation is as follows: fresh blood pressure of SD rats was collected, and after centrifugation at 300rpm for 10 minutes, the supernatant was removed to obtain red blood cells. The red blood cells were rinsed 3 times with normal saline, and the collected red blood cells were suspended in normal saline to prepare a red blood cell suspension with a volume concentration of 4%. The red blood cell suspension was then mixed with the hydrogel extract in a centrifuge tube at a volume ratio of 1:1 and incubated at 37°C and 120rpm for 1 hour. After centrifugation, 100μL of supernatant was transferred to a 96-well plate, and the optical density value was measured at 542nm. In this experiment, the hemolysis rate can be calculated using the sample group, negative control group, and positive control group.

[0105] The calculation formula for the hemolysis rate is: (OD1-OD2) / (OD3-OD2)×100%; where OD1 is the optical density value of the sample group measured at 542 nm; OD2 is the optical density value of the negative control group measured at 542 nm; OD3 is the optical density value of the positive control group measured at 542 nm.

[0106] In this experiment, the applicant selected the following groups of examples as sample groups: Example 2, Example 3 and Example 6 as sample groups. Figure 18 . Figure 18 The following are experimental pictures of blood compatibility of different sample groups and bar graphs of hemolysis rates of different sample groups. Figure 18 On the left are pictures of blood compatibility experiments on different sample groups. Figure 18 The right side of is a bar graph of the hemolysis rate of different sample groups. Figure 18 Analysis revealed that the interior of the centrifuge tube in the positive control group (Triton) was bright red, indicating lysis of surface red blood cells. In contrast, the sample group containing the hydrogel sample remained almost colorless, indicating no significant hemolysis. Furthermore, the hemolysis rate of the positive control group was over 90%, while the hemolysis rates of the sample groups containing the hydrogel were all below 5%, demonstrating that the hydrogels in Examples 2, 3, and 6 all possessed excellent hemocompatibility. Therefore, the hydrogels prepared in this protocol exhibit both excellent cytocompatibility and hemocompatibility, making them ideal candidate materials for novel biomedical dressings.

[0107] (11) Effect of hydrogel on healing of diabetic wounds

[0108] First, diabetic rats were established: high-dose streptozotocin (65 mg / kg) was injected into the abdominal cavity of SD rats, and the blood glucose level in the tail vein was measured regularly. SD rats whose blood glucose levels exceeded 16.7 mmol / L for 2 consecutive weeks were selected for subsequent experiments. During the entire animal experiment, the blood glucose level was maintained above 16.7 mmol / L. After obtaining SD rats with diabetes, two full-thickness skin wounds with a diameter of 8 mm were created on the backs of these rats, and the epidermis and dermis were removed to expose the subcutaneous tissue. Subsequently, 100 μL, 10 8 CFU / mL of Staphylococcus aureus was used to establish a rat diabetic wound model. Rats infected for 24 hours were randomly divided into five groups: the first group had 200 μL of normal saline applied to the wound as a control group; the second group had 200 μL of the hydrogel prepared in Example 3 applied to the wound; the third group had 200 μL of the hydrogel prepared in Example 6 applied to the wound; the fourth group had 200 μL of the hydrogel prepared in Example 2 applied to the wound; the fifth group had 200 μL of the hydrogel prepared in Example 2 applied to the wound and irradiated with 808 nm NIR at 0.5 W / cm 2 The wound was irradiated with an intensity of 10 minutes. After the above treatment, the wound was covered and fixed with a sterile dressing. High-quality pictures of the wound on the back of the rat were taken under anesthesia on the 0th, 3rd, 7th and 14th days after treatment. Figure 19 . Figure 19 Images of diabetic wounds repaired with different hydrogels were taken at different time points. Measurements were taken using ImageJ software, and the wound healing rate was calculated based on the results. The formula for calculating the wound healing rate is as follows:

[0109] Wound healing rate (%) = (A0-At) × 100%; where A0 is the initial wound area and At is the wound area on day t. Figure 20 The relationship between the wound healing rate and time of the rat back wound is shown in the figure. Figure 19 and Figure 20 Analysis shows that after the seventh day after surgery, the actual pictures and healing rates of the wounds in the fourth and fifth groups were much better than those in the first, second and third groups. This shows that the hydrogel in Example 2 has a good healing effect on diabetic wounds. And as the time after surgery increases, on the 14th day after surgery, Figure 20It can be seen that the healing rate of the diabetic infection wounds in the fourth and fifth groups was close to 100% on the fourteenth day, which shows that the wounds in the fourth and fifth groups were close to completely healed on the fourteenth day. Among the two groups, the healing effect and healing rate of the fifth group were higher than those of the fourth group. The difference between the fifth group and the fourth group is that the fifth group treated the diabetic infection wounds by combining the hydrogel prepared in Example 2 with photothermal therapy. It can be seen that the hydrogel prepared in this scheme can be combined with photothermal therapy, and the combination of the two can produce a synergistic effect, thereby increasing the healing rate of diabetic infection wounds. The main reason for this is that the hydrogel in Example 2 is modified with phenylboronic acid to form a dynamic covalent bond (phenylboronic acid ester bond) with polyvinyl alcohol, so that the hydrogel can restore its integrity after damage, extend the service life of the dressing, reduce the frequency of replacement, and reduce the risk of secondary injury. By loading metformin into the hydrogel, metformin can relieve inflammation and oxidative stress, promote the production of fibroblasts and the formation of granulation tissue, thereby accelerating wound healing. Furthermore, mesoporous polydopamine can convert laser energy into local heat. By combining this photothermal property with photothermal therapy, the hydrogel dressing can reach 49.9°C in 10 minutes under infrared laser irradiation. This moderate temperature can not only effectively kill bacteria, but also reduce the necrosis of normal cells. At the same time, it can also enhance local blood circulation, promote fibroblast proliferation and collagen synthesis, promote tissue repair and regeneration, and thus accelerate wound healing. In addition, mesoporous polydopamine is modified by L-arginine in the hydrogel. The cationic effect of L-arginine can effectively kill bacteria, while also reducing oxidative stress and promoting vascularization. Therefore, under the synergistic effect of the above-mentioned multiple raw materials, the hydrogel of Example 2 has good antibacterial and sterilization, avoids wound infection, quickly stops bleeding of the wound, and also effectively releases metformin, thereby achieving the purpose of a one-stop solution to multiple problems existing in diabetic infected wounds, thereby achieving an improvement in the healing rate of diabetic wounds.

[0110] In this experiment, the colony formation experiment was also performed on the third day after surgery to evaluate the in vivo antibacterial effect of the hydrogel. The operation can be as follows: on the third day after surgery, all secretions from the wound were collected with a sterile cotton swab. The swab was placed in 3mL of liquid culture medium and incubated for 24 hours. The culture medium was then diluted 10,000 times with PBS, 100μL of the diluted solution was applied to the agar plate, and incubated at 37°C for 18-24 hours. The antibacterial effect of the hydrogel was determined by counting the Staphylococcus aureus colonies on the agar plate, and the results were as follows: Figure 21 and Figure 22 .in, Figure 21 These are pictures of the colony counts of Staphylococcus aureus on five groups of agar plates. Figure 22 The bar graph shows the survival rate of Staphylococcus aureus colonies on five groups of agar plates. Figure 21It can be seen that a large number of bacteria survived on the wounds treated with physiological saline and Example 3, while only a small number of bacteria survived on the wounds of Example 6, Example 2, and Example 2+NIR. Figure 22 , Figure 22 The bacterial survival rate of the wound treated with the hydrogel of Example 2 combined with photothermal therapy was the lowest, indicating that the hydrogel of Example 2 combined with photothermal therapy has a strong antibacterial effect and good antibacterial effect on diabetic wounds. This is mainly due to the synergistic mechanism of the hydrogel's inherent antibacterial activity and the photothermal-induced bacterial destruction, which enables the hydrogel of Example 2 combined with photothermal therapy to have a good antibacterial effect. This shows that the use of the hydrogel of Example 2 combined with photothermal therapy can better promote the healing of diabetic wounds.

[0111] The above describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and description merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a hydrogel with photothermal antibacterial and healing-promoting properties, characterized in that: It includes: Mesoporous polydopamine was dispersed in a Tris-HCl solution with a pH of 8.5 according to a certain proportion, and then L-arginine was added to the Tris-HCl solution at a mass ratio of 1:20 to mesoporous polydopamine to prepare L-MPDA; 3-(Aminomethyl)phenylboronic acid hydrochloride and 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride were fully dissolved in a hyaluronic acid solution at a mass ratio of 47:80, and the pH thereof was adjusted to 6.5 with an alkali solution to obtain a phenylboronic acid-modified hyaluronic acid mixture; the phenylboronic acid-modified hyaluronic acid mixture was dialyzed and freeze-dried to obtain HA-PBA; Metformin and purified L-MPDA were dissolved in deionized water at a mass ratio of 2:1, and purified HA-PBA was added in proportion to prepare a mixed solution B; then, a polyvinyl alcohol solution was added to the mixed solution B at a volume ratio of 1:1 to the mixed solution B and mixed evenly to prepare a hydrogel.

2. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 1, wherein: The mesoporous polydopamine is obtained by a template method, and the specific steps of preparing the mesoporous polydopamine by the template method include: Dopamine and Pluronic F-127 were fully dispersed in an ethanol aqueous solution at a mass ratio of 3:2, and then 1,3,5-trimethylbenzyl was added at a volume ratio of 8:25 to ethanol and ultrasonically dispersed to obtain an emulsion D; while stirring the emulsion D, an ammonia aqueous solution at a volume ratio of 1:200 to 1:300 was added to the emulsion D to obtain a mixed solution E; The coarse particles in the mixed solution E are collected by centrifugation and ultrasonicated in an ethanol / acetone mixed solution with a volume ratio of 2:1; and then the mesoporous polydopamine is prepared by washing, centrifugation and freeze-drying.

3. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 1, wherein: The purification steps of L-DMPA include: collecting the obtained L-MMPA by centrifugation, washing and freeze-drying in sequence to obtain purified L-DMPA.

4. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 1, wherein: The purification steps of HA-PBA include: dialyzing and freeze-drying the obtained HA-PBA in sequence to obtain purified HA-PBA.

5. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 4, wherein: The dialysis operation used a dialysis bag with a molecular cutoff value of 6-8 kDa. The dialysis operation conditions were dialysis with deionized water at room temperature for 5 days, and the deionized water was changed twice a day.

6. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 1, wherein: The preparation method of the polyvinyl alcohol solution is as follows: polyvinyl alcohol is dispersed in deionized water according to a certain proportion, and the solution is prepared by heating the solution in a water bath at 95° C. until the polyvinyl alcohol is completely dissolved.

7. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 1, wherein: The concentration of the L-MPDA is 0.25 mg / mL to 1.0 mg / mL; the concentration of the hyaluronic acid solution is 5 mg / mL; the concentration of the metformin is 1.0 mg / mL; the concentration of the HA-PBA is 20 mg / mL; and the concentration of the polyvinyl alcohol solution is 30 mg / mL.

8. The method for preparing the hydrogel with photothermal antibacterial and healing-promoting properties according to claim 1, wherein: Purified HA-PBA and metformin were added to solution B at a mass ratio of 1:

20.

9. A hydrogel with photothermal antibacterial and healing-promoting properties, characterized in that: The hydrogel is prepared by the preparation method of the hydrogel with photothermal antibacterial and healing-promoting properties as described in any one of claims 1 to 8. The hydrogel can be combined with photothermal therapy to promote the healing of diabetic wounds.

10. Use of the hydrogel with photothermal antibacterial and healing-promoting properties as claimed in claim 9 in the preparation of diabetic wound dressing.

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