A composite hydrogel for wound repair and its preparation method and application

Abstract

The application discloses a kind of composite hydrogel for wound repair and its preparation method and application, belong to medical material technical field.Methyl methacrylated gelatin, hydroxyethyl methacrylate and oxidized dextran are mixed, copper sulfide nanoparticles, crosslinking agent and photoinitiator are added, stirred uniformly and placed in mold, and UV irradiation is used.Aldehyde group on ODex chain and amino group on GelMA chain occur Schiff base reaction, form dynamic covalent bond, constitute reversible crosslinking point, copolymerization reaction occurs between HEMA and methacryloyl on GelMA molecular chain, and stable covalent crosslinking network is formed.In this process, CuS NPs are effectively captured and stably dispersed in the network by physical action, and the crosslinked hydrogel is soaked in deionized water to balance, to obtain the target composite hydrogel.The composite hydrogel has excellent mechanical strength, pH-responsive swelling performance and biocompatibility, and can realize efficient antibacterial and endogenous immune regulation by combining near-infrared photothermal therapy, effectively promoting wound repair.

Description

Technical Field

[0001] This invention relates to the field of medical materials technology, and in particular to a composite hydrogel for wound repair, its preparation method, and its application. Background Technology

[0002] Currently, mainstream clinical treatments for infected burns suffer from inherent drawbacks, including painful debridement, potential damage to newly formed tissue, and limited efficacy in the face of bacterial resistance. Therefore, developing novel treatment strategies that can actively regulate the wound microenvironment is urgently needed.

[0003] Against this backdrop, hydrogel dressings are considered ideal wound dressings due to their ability to maintain a moist wound environment, absorb exudate, and exhibit good biocompatibility. However, most traditional hydrogels serve only as passive barriers or drug carriers, lacking intrinsic biological functions and struggling to address the complex pathological challenges of burn wounds. For example, while some synthetic polymer hydrogels are mechanically stable, they exhibit poor degradation and insufficient bioactivity, potentially triggering chronic inflammation; while some natural polymer hydrogels, although improving biocompatibility, often lack sufficient immunomodulatory and antibacterial capabilities in the complex burn environment.

[0004] While some existing technologies attempt to improve hydrogel performance by introducing functional components, they often have limitations. For example, strategies focusing on dynamic cross-linking often sacrifice mechanical strength, while strategies focusing on antibacterial function often lack biocompatibility and microenvironment responsiveness. These improvements mostly remain at the level of functional superposition and fail to systematically and synergistically regulate core pathological processes such as oxidative stress and immune imbalance. Furthermore, existing strategies often rely on exogenous active substances, which not only increases costs and process complexity but also carries potential safety risks.

[0005] In summary, there is an urgent need in this field for a novel composite hydrogel dressing that can not only cover the basic needs of burn wounds, but also actively transform the unfavorable inflammatory microenvironment into a regenerative microenvironment that promotes repair through its inherent and multifunctional synergistic effects, thereby achieving efficient and safe repair of burns. Summary of the Invention

[0006] In view of the aforementioned shortcomings and deficiencies of existing technologies, this invention provides a composite hydrogel for wound repair, its preparation method, and its applications. It aims to solve the technical problem that existing wound dressings, due to their low functional integration and uncontrollable antibacterial behavior, cannot meet the requirements of precision medicine for dynamic regulation of the wound microenvironment. This composite hydrogel forms a double cross-linked network through Schiff base reaction and photo-initiated polymerization, possessing excellent mechanical strength and stable adhesion to moist wounds. Simultaneously, the CuS nanoparticles introduced into the system can generate a photothermal effect under near-infrared light irradiation, thereby achieving on-demand and controllable antibacterial function and drug release. The hydrogel dressing ultimately prepared by this invention can closely adhere to dynamic wounds and perform precise treatment under the control of external light signals, providing a novel, functionally integrated solution for the efficient management of complex wounds.

[0007] According to one aspect of the present invention, a method for preparing a composite hydrogel for wound repair is provided, comprising: S1, preparing methacrylamide gelatin: dissolving gelatin in PBS buffer, adding methacrylic anhydride to react, diluting with PBS buffer after the reaction is complete, and obtaining methacrylamide gelatin after dialysis, pre-freezing, and freeze-drying; S2, preparing oxidized dextran: dissolving sodium periodate in deionized water, then adding it to the dextran solution to react, obtaining white oxidized dextran solid after dialysis and freeze-drying, and storing it in the dark; S3, preparing a prepolymer solution: dissolving methacrylamide gelatin in deionized water, then adding hydroxyethyl methacrylate, stirring evenly, adding oxidized dextran, and stirring until... Completely dissolve to form a homogeneous solution; S4, prepare the precursor solution: add copper sulfide nanoparticle dispersion, crosslinking agent N,N'-methylenebisacrylamide and photoinitiator to the solution obtained in S3 in sequence, mix evenly to obtain the precursor solution; S5, molding and crosslinking: after degassing the obtained precursor solution, inject it into the mold, and crosslink and solidify it under ultraviolet light to obtain the target composite hydrogel, namely P(HEMA-co-GelMA) / ODex / CuS hydrogel, where HEMA refers to hydroxyethyl methacrylate, GelMA refers to methacrylamide gelatin, P(HEMA-co-GelMA) represents the copolymer of HEMA and GelMA, ODex refers to oxidized dextran, and CuS refers to copper sulfide.

[0008] Optionally, in S1, gelatin and PBS are dissolved at a mass-to-volume ratio of 1:10 at 60°C, and the mass ratio of added methacrylic anhydride to gelatin is 5:4. After the reaction is complete, 4 times the volume of PBS buffer is added for dilution.

[0009] Optionally, in S2, 3.0 g of sodium periodate is dissolved in 80 mL of deionized water and then added to 320 mL of a 1.25% (w / v) dextran solution, and the mixture is reacted in the dark at 25°C.

[0010] Optionally, in S3, the amount of methacrylamide gelatin added to deionized water is 3 wt%; the volume ratio of added hydroxyethyl methacrylate to deionized water is 2:5; and the amount of oxidized dextran added is 3 wt%.

[0011] Optionally, in S3, methacrylamide gelatin is dissolved in deionized water at 60°C, cooled to room temperature, hydroxyethyl methacrylate is added, stirred evenly, then heated to 50°C, oxidized dextran is added, and stirred until completely dissolved to form a homogeneous solution.

[0012] Optionally, in S4, the concentration of the added copper sulfide nanoparticle dispersion is 0.4 mg / mL, and it is pretreated by ultrasonication at 300W power before use.

[0013] Optionally, in S4, the amount of crosslinking agent N,N'-methylenebisacrylamide added is 1.0 wt%; the amount of photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone added is 1.0 wt%.

[0014] Optionally, in S5, the degassing process is performed under an ultrasonic power of 300 W; the ultraviolet wavelength is 365 nm.

[0015] According to another aspect of the present invention, a composite hydrogel for wound repair is provided, which is prepared based on the preparation method of the composite hydrogel for wound repair as described above, and has a multi-level cross-linked structure, including a first network formed by dynamic cross-linking of ODex and GelMA, and a second network formed by HEMA and GelMA copolymer backbone and uniformly dispersed CuS nanoparticles under the action of ultraviolet light and photoinitiator.

[0016] According to another aspect of the present invention, the application of the composite hydrogel for wound repair as described above in the preparation of wound dressings is provided. When used, the wound dressings can be used in conjunction with near-infrared light irradiation to enhance the antibacterial effect through the synergistic effect of photothermal ablation and CuS nanoparticle-mediated bactericidal action.

[0017] The beneficial effects of this invention are:

[0018] (1) Innovative structure to achieve functional synergy: An efficient method was adopted to successfully prepare a composite hydrogel with a multi-level cross-linked (dual network) structure (ODex and GelMA dynamically cross-link to form the first network, HEMA and GelMA copolymer backbone and uniformly dispersed CuS nanoparticles form the second network). Its irregular structure is composed of P(HG) copolymer backbone with uniformly distributed CuS particles, and its flexibility is achieved through the dynamic cross-linking of ODex / GelMA. By introducing HEMA and GelMA copolymer to form P(HG) backbone, the hydrophilicity and mechanical stability of HEMA make up for the defects of low viscosity and easy swelling of GelMA, improve the structural integrity of hydrogel on moist wound, and solve the problems of complex preparation and insufficient wound adaptability of traditional functional hydrogels.

[0019] (2) Long-lasting wet adhesion and sealing: Based on dynamic Schiff base reaction, it exhibits excellent wet adhesion performance on biological tissue surface, can firmly adhere to moist and irregular wound surface, form physical sealing barrier, effectively isolate external microorganisms and prevent body fluid leakage.

[0020] (3) Strong wound management ability: It has a rapid and moderate swelling ability, which can efficiently absorb excessive exudate from the wound and avoid fluid accumulation. At the same time, its stable three-dimensional network structure can prevent excessive swelling. After absorbing the liquid, it can still maintain the integrity of the structure and is not easy to collapse, thus realizing intelligent management of wound exudate.

[0021] (4) Excellent biocompatibility: The matrix materials are all derived from natural polymers and have good biocompatibility. Their porous structure provides a place for cell migration and proliferation, while the mild cross-linking process ensures the activity of the loaded cells.

[0022] (5) Photothermal Synergistic High-Efficiency Antibacterial Effect: By introducing CuS NPs (copper sulfide nanoparticles), this composite hydrogel can generate local high temperatures under near-infrared light irradiation, and its photothermal effect is similar to that of Cu. 2+ The inherent antibacterial activity forms a synergistic effect, which can rapidly and broadly kill bacteria and remove biofilms. This synergistic mechanism can effectively combat a variety of pathogens and is not prone to inducing drug resistance.

[0023] (6) Relying on the endogenous regulatory capacity of materials, macrophages are transformed into the M2 repair subtype, which simultaneously solves the two core problems of burn wound infection and excessive inflammation, and adapts to the complex pathological needs of burn wounds. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic diagram illustrating the preparation process and cross-linking mechanism of the composite hydrogel for wound repair according to the present invention;

[0026] Figure 2 The image shows a scanning electron microscope image and the aperture size. Figure 2 (B1) Figure 2 (B2) Figure 2 (B3) Figure 2 (B4) are scanning electron microscope images and pore sizes of samples 1, 2, 3 and 4, respectively;

[0027] Figure 3 The results are the adhesion strength test results, where, Figure 3 (A) represents the adhesion strength of samples 1-4. Figure 3 (B) is the adhesion cycle curve of sample 4;

[0028] Figure 4 The swelling test results are for sample 4;

[0029] Figure 5 The results are for cell viability and hemolysis tests, among which, Figure 5 (A) shows the cell viability test results for samples 1-4. Figure 5 (B) shows the hemolysis rate test results for samples 1-4;

[0030] Figure 6 For photothermal heating, antibacterial effect and Cu 2+ Release curve, in which, Figure 6 (A) shows the photothermal heating effect of samples 1-4. Figure 6 (B) shows the inhibition curves of samples 1-4 against Escherichia coli. Figure 6 (C) shows the inhibition curves of Staphylococcus aureus in samples 1-4. Figure 6 (D) represents Cu in sample 4. 2+ Release curve;

[0031] Figure 7 The analysis included images of wound healing progress, wound healing rate, and quantitative analysis of macrophage fluorescence staining. Figure 7 (A) shows the wound healing effects after photothermal treatment of the blank control, 3M dressing, samples 1 and 4, and samples 1 and 4. Figure 7 (B) shows the wound healing rates at 3, 7, and 12 days after photothermal treatment of the blank control, 3M dressing, samples 1 and 4, and samples 1 and 4. Figure 7 (C) represents the blank control, 3M dressing, samples 1 and 4, and quantitative analysis of macrophage fluorescence staining after photothermal treatment of samples 1 and 4. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of them. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present application can be combined with each other.

[0033] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0034] Example 1: This embodiment of the invention provides a method for preparing a composite hydrogel for wound repair. The preparation process and cross-linking mechanism of the composite hydrogel are as follows. Figure 1 As shown, the preparation method includes the following steps:

[0035] S1, Preparation of GelMA: Gelatin (Gel) was dissolved in PBS at a mass-to-volume ratio of 1:10 at 60°C. Methacrylic anhydride (MA, mass-to-gelatin ratio of 5:4) was added dropwise and reacted for 2 hours. After dilution with 4 times the volume of PBS, the mixture was dialyzed for one week. After pre-freezing and freeze-drying, the product—methacryloyl gelatin, namely Gelatin methacryloyl (GelMA) was obtained.

[0036] S2, Preparation of ODex: Dissolve 3.0 g of sodium periodate (NaIO4) in 80 mL of deionized water, then add it to 320 mL of a 1.25% (w / v) dextran (Dex) solution. React at room temperature (RT) 25°C in the dark for 24 hours. After dialyzing and freeze-drying for 3 days, white oxidized dextran (ODex) solid is obtained and stored in the dark.

[0037] S3, Preparation of prepolymer solution: Dissolve methacrylamide gelatin (GelMA) in deionized water and stir at about 60°C until completely dissolved. After cooling to room temperature, add hydroxyethyl methacrylate (HEMA) and stir until homogeneous. Then heat to 50°C and add oxidized dextran (ODex). Stir until completely dissolved to form a homogeneous solution. In this step, the aldehyde group on the ODex chain reacts with the amino group on the GelMA chain to form a Schiff base reaction, forming a dynamic covalent bond and constituting a reversible crosslinking point.

[0038] S4, Preparation of precursor solution: Copper sulfide (CuS) nanoparticle dispersion, crosslinking agent N,N'-methylenebisacrylamide (MBA) and photoinitiator (I2959) are added sequentially to the solution obtained in S3, and the mixture is stirred and mixed evenly at room temperature to obtain the precursor solution;

[0039] S5: Molding and cross-linking: After degassing the obtained precursor solution, it is injected into the mold and cross-linked and cured under ultraviolet light (the methacryloyl groups on the HEMA and GelMA molecular chains undergo a copolymerization reaction to form a stable covalent cross-linking network, and CuSNPs are stably dispersed in the network through physical action), thus obtaining the target composite hydrogel P(HEMA-co-GelMA) / ODex / CuS.

[0040] In step S3, the amount of GelMA added to deionized water is 3 wt%; the volume ratio of added HEMA to deionized water is 2:5 (e.g., the volume of added HEMA is 2.4 mL, corresponding to the volume of deionized water used is 6 mL); and the amount of ODex added is 3 wt%.

[0041] In step S4, the concentration of CuS nanoparticle dispersion was 0.4 mg / mL, the addition amount was 1 mL, and it was pretreated by ultrasonication at 300W power for 1 hour before use; the addition amount of MBA was 1.0 wt%; and the addition amount of photoinitiator I2954 (2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone) was 1.0 wt%.

[0042] In step S5, the degassing process is carried out under an ultrasonic power of 300 W for 5 minutes; the ultraviolet light wavelength is 365 nm and the irradiation time is 5 minutes; the mold is a cylindrical or dumbbell-shaped polytetrafluoroethylene mold.

[0043] The composite hydrogel prepared by the above method has a multi-level cross-linked structure, including a first network formed by the dynamic cross-linking system of ODex and GelMA, and a second network formed by the P(HG) copolymer framework and uniformly dispersed CuS nanoparticles under the action of ultraviolet light and photoinitiator (I2959).

[0044] It should be noted that P(HG) is also an abbreviation for P(HEMA-co-GelMA), where P represents polymer, H refers to HEMA, G refers to GelMA, and co is an abbreviation for copolymer. Figure 1 In this context, P(HEMA-GelMA) / ODex / CuS is equivalent to P(HEMA-co-GelMA) / ODex / CuS; —C=O represents a carbonyl group; —CHO represents an aldehyde group; —NH2 represents an amino group; —C=N— represents an imino group.

[0045] The composite hydrogel in this invention can accelerate Cu through near-infrared photothermal effect (CuS mediated). 2+ Release and absorption of wound exudate; Cu 2+ The sustained-release and photothermal effects synergistically combat bacteria (inhibiting Staphylococcus aureus by 98%), and are less likely to induce drug resistance. Utilizing the material's endogenous regulatory capabilities, it promotes the transformation of macrophages into the M2 repair subtype, simultaneously addressing the two core issues of burn wound infection and excessive inflammation, thus adapting to the complex pathological needs of burn wounds. Furthermore, the introduction of HEMA and GelMA copolymerization to form a P(HG) framework, where the hydrophilicity and mechanical stability of HEMA compensate for the low viscosity and easy swelling of GelMA, improving the structural integrity of the hydrogel in moist wounds, is a key feature. Moreover, the preparation process is simple and convenient, solving the problems of complex preparation and insufficient wound adaptability of traditional functional hydrogels.

[0046] The composite hydrogel of this invention can be used to prepare wound dressings suitable for skin wounds caused by mechanical injury, burns, and scalds, especially infected wounds. When used as a wound dressing, it can be combined with 808nm near-infrared laser irradiation to enhance the antibacterial effect through the synergistic effect of photothermal ablation and CuS NPs (copper sulfide nanoparticles)-mediated bactericidal action.

[0047] Example 2: This example is used to characterize the properties of the composite hydrogel prepared in Example 1, and several control groups are set up.

[0048] Control group 1: PHEMA hydrogel:

[0049] S101. Add 2.4 ml of HEMA (hydroxyethyl methacrylate) to a beaker containing 6 mL of deionized water and stir at medium speed for 15 minutes at room temperature.

[0050] S102, add N,N'-methylenebisacrylamide (MBA), stir at room temperature for 10 minutes until evenly dispersed;

[0051] S103, add 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone (I2959), and stir at room temperature for 10 minutes until completely dissolved;

[0052] S104: The precursor solution obtained in S103 was degassed under 300 W ultrasonication for 5 minutes and then poured into a mold. It was then cured under 365 nm ultraviolet light for 5 minutes to obtain sample 1—PHEMA hydrogel.

[0053] Figure 2 (B1) is an electron micrograph of the surface morphology of sample 1. It can be observed that the pure PHEMA hydrogel has a loose and porous structure with a large pore size and an average pore size of 22.68 μm.

[0054] Control group 2: P(HG) hydrogel:

[0055] S201. Add 3 wt% methacrylamide gelatin (GelMA) to a beaker containing 6 mL of deionized water, and stir at a moderate speed at 60°C for 30 minutes until completely dissolved to form a uniform and transparent GelMA solution.

[0056] S202, add 2.4 mL HEMA to the GelMA solution and stir at medium speed for 15 minutes at room temperature;

[0057] Add N,N'-methylenebisacrylamide (MBA) to S203 and stir at room temperature for 10 minutes until evenly dispersed;

[0058] S204, add 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone (I2959), and stir at room temperature for 10 minutes until completely dissolved;

[0059] S205: The precursor solution obtained from S204 was degassed under 300 W ultrasonication for 5 minutes and then poured into a mold. It was then cured under 365 nm ultraviolet light for 5 minutes to obtain sample 2-P(HG) hydrogel.

[0060] Figure 2 (B2) is an electron microscopy surface morphology image of sample 2. It can be observed that the P(HG) hydrogel exhibits a dense honeycomb porous structure with an average pore size reduced to 13.02 μm. This is because the acryloyloxy group (-C=C-) in GelMA and the double bond in HEMA undergo free radical copolymerization through photoinitiated polymerization, forming a three-dimensional network.

[0061] Control group 3: P(HG) / O hydrogel:

[0062] S301. Add 3 wt% methacrylamide gelatin (GelMA) to a beaker containing 6 mL of deionized water, and stir at a moderate speed at 60°C for 30 minutes until completely dissolved to form a uniform and transparent GelMA solution.

[0063] S302, add 2.4 mL HEMA to the GelMA solution and stir at medium speed for 15 minutes at room temperature;

[0064] S303, lower the temperature to 50°C, add 3 wt% ODex (oxidized dextran) to the solution, and stir for 15 minutes until completely dissolved;

[0065] Add N,N'-methylenebisacrylamide (MBA) to S304 and stir at room temperature for 10 minutes until evenly dispersed;

[0066] Add 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone (I2959) to S305 and stir at room temperature for 10 minutes until completely dissolved;

[0067] S306: The precursor solution obtained in S305 was degassed under 300 W ultrasonication for 5 minutes and then poured into a mold. It was then cured under 365 nm ultraviolet light for 5 minutes to obtain sample 3-P(HG) / O hydrogel.

[0068] Figure 2 (B3) is an electron micrograph of the surface morphology of sample 3. It can be observed that after the addition of ODex, the Schiff base reaction with GelMA further reduces the pore size of the P(HG) / O hydrogel.

[0069] Experimental Group 1: P(HG) / O / CuS hydrogel (i.e., the composite hydrogel P(HEMA-co-GelMA) / ODex / CuS in Example 1):

[0070] S1. Add 3 wt% methacrylamide gelatin (GelMA) to a beaker containing 6 mL of deionized water, and stir at a moderate speed at 60°C for 30 minutes until completely dissolved to form a uniform and transparent solution.

[0071] S2, add 2.4 mL HEMA to the solution and stir at medium speed for 15 minutes at room temperature;

[0072] S3, lower the temperature to 50°C, add 3 wt% ODex to the solution, and stir for 15 minutes until completely dissolved;

[0073] S4, add 1 mL of CuS NPs (dispersed concentration 0.4 mg / mL) dropwise and stir for 10 minutes until the solution is uniformly dispersed;

[0074] S5, add N,N'-methylenebisacrylamide (MBA), stir at room temperature for 10 minutes until evenly dispersed;

[0075] S6, add 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone (I2959), and stir at room temperature for 10 minutes until completely dissolved;

[0076] S7. After degassing the precursor solution under 300 W ultrasonication for 5 minutes, it was poured into a mold and cured under 365 nm ultraviolet light for 5 minutes to obtain sample 4—P(HG) / O / CuS hydrogel.

[0077] Figure 2 (B4) is an electron micrograph of the surface morphology of sample 4. It can be observed that due to the multi-level cross-linking mechanism, sample 4 has the smallest average pore size (5.33 μm), which is beneficial to cell adhesion, proliferation and drug delivery. In addition, CuS NPs can be observed to adhere to the surface of the P(HG) / O / CuS hydrogel pores.

[0078] Reference Figure 3 , Figure 3 For the adhesion strength test results, such as Figure 3 As shown in (A), the hydrogel of sample 4 exhibits the highest adhesion strength. Figure 3 (B) Further shows the adhesion cycle curve of sample 4, reflecting that it has good repeatable adhesion performance and relatively stable adhesion strength. In practical applications, this hydrogel can not only provide a clean initial environment for wounds, but also has the potential for reusability.

[0079] Figure 4 To analyze the swelling equilibrium rate of sample 4 under different pH conditions, the swelling test was conducted to determine the swelling test results. Under weakly acidic conditions, sample 4 showed the highest swelling rate, indicating a highly efficient ability to absorb and manage wound exudate. This is due to the weakening of dynamic ionic and coordination bonds in the polymer network and the increase in the dispersion of CuS NPs, both of which together lead to the relaxation of the polymer network, thereby enhancing the absorption of water.

[0080] Figure 5 For cell viability and hemolysis test results, by Figure 5 (A) It can be seen that the number of viable cells increased significantly from day 1 to day 5 throughout the entire cell compatibility test process, with sample 4 showing a cell survival rate as high as 120% on day 5, although due to Cu 2+ The concentrated release was slightly lower than other samples, but it still showed a positive effect. Furthermore, compared with the H2O and NaCl control groups, Figure 5 (B) The blood compatibility test showed that none of the four groups of samples had obvious hemolysis, indicating that they have the potential for clinical application.

[0081] Figure 6 (A) shows the actual temperature rise of four samples under 808nm laser irradiation. Sample 4 shows obvious temperature rise and has great potential for subsequent antibacterial and in vivo treatment. Figure 6 (B) and Figure 6 (C) shows that samples 1 and 2 had extremely low antibacterial rates, while sample 4, combined with PTT (photothermal therapy), exhibited the highest antibacterial efficiency. This is attributed to the excellent photothermal effect and active bactericidal properties of CuS NPs. It was demonstrated that the P(HG) / O / CuS hydrogel significantly inhibited the growth of Escherichia coli and Staphylococcus aureus (with an inhibition rate of 98% against Staphylococcus aureus), and possessed strong antibacterial activity against both Gram-negative and Gram-positive bacteria. Furthermore, the antibacterial activity and photothermal properties were primarily related to the doped CuS NPs. The Cu²⁺ release behavior of sample 4 was detected using inductively coupled plasma (ICP) technology. Figure 6 (D) The results show that its release curve conforms to the biphasic Fick diffusion mechanism. In the figure, E. coli refers to Escherichia coli, S. aureus refers to Staphylococcus aureus, NIR(-) indicates before photothermal treatment (i.e., without near-infrared light irradiation), and NIR(+) indicates after photothermal treatment (i.e., after near-infrared light irradiation).

[0082] The healing effect results are as follows Figure 7 As shown in (A), Blank represents the blank control group without any dressing / hydrogel, 3M represents the control group with 3M dressing, NIR- represents before photothermal treatment, and NIR+ represents after photothermal treatment. Figure 7 (A) The wound healing photos of mice show that the sample 4+PTT combination (i.e. P(HG) / O / CuS NIR+ in the figure) has the best wound healing effect. The synergistic effect produced excellent antibacterial effect and controlled the inflammatory response in the early stage of wound healing. Figure 7 (B) shows that after 12 days, the wound healing rate of the sample 4+PTT combination reached 93%, far exceeding the performance of other examples. When CuS NPS is combined with PTT treatment, it can also promote fibroblast adhesion and proliferation and accelerate epithelial regeneration. Figure 7 (C) demonstrates the planned transformation ability of macrophages. By euthanizing mice on day 12 and staining macrophage markers on epidermal tissue, the M2 / M1 ratio can be compared. It can be seen that the 4+PTT combination of samples showed a clear trend toward M2, promoting the transformation to repair.

[0083] In summary, the composite hydrogel prepared by this invention has excellent mechanical strength, pH-responsive swelling properties, and biocompatibility. Combined with near-infrared photothermal therapy (PTT), it can achieve efficient antibacterial and endogenous immune regulation, improve the microenvironment for burn wound healing, and promote the transformation of macrophages to the M2 repair subtype, effectively promoting wound repair. It is suitable for the field of burn wound dressings.

[0084] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0085] The steps in the method of this invention can be adjusted, combined, or deleted according to actual needs. The technical features can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the embodiments are described. However, as long as the combinations of these technical features do not contradict each other, they should all be considered within the scope of this invention.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite hydrogel for wound repair, characterized in that, include: S1, Preparation of methacrylamide gelatin: Dissolve gelatin in PBS buffer, add methacrylic anhydride to react, dilute with PBS buffer after reaction, and obtain methacrylamide gelatin after dialysis, pre-freezing and freeze-drying. S2, Preparation of oxidized dextran: Sodium periodate was dissolved in deionized water and then added to the dextran solution for reaction. After the reaction was completed, the solution was dialyzed and freeze-dried to obtain white oxidized dextran solid, which was then stored in the dark and dry place. S3, Preparation of prepolymer solution: Dissolve methacrylamide gelatin in deionized water, then add hydroxyethyl methacrylate, stir until homogeneous, add oxidized dextran, and stir until completely dissolved to form a homogeneous solution; S4, Preparation of precursor solution: Add copper sulfide nanoparticle dispersion, crosslinking agent N,N'-methylenebisacrylamide and photoinitiator sequentially to the solution obtained in S3, mix evenly to obtain precursor solution; S5, Molding and Crosslinking: After degassing the obtained precursor solution, it is injected into a mold and crosslinked and cured under ultraviolet light to obtain the target composite hydrogel, namely P(HEMA-co-GelMA) / ODex / CuS hydrogel, where HEMA refers to hydroxyethyl methacrylate, GelMA refers to methacrylamide gelatin, P(HEMA-co-GelMA) represents the copolymer of HEMA and GelMA, ODex refers to oxidized dextran, and CuS refers to copper sulfide. In S4, the concentration of the added copper sulfide nanoparticle dispersion was 0.4 mg / mL, and it was pretreated by ultrasonication at 300 W before use; the amount of crosslinking agent N,N'-methylenebisacrylamide added was 1.0 wt%; and the amount of photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropanone added was 1.0 wt%.

2. The method for preparing the composite hydrogel for wound repair according to claim 1, characterized in that, In S1, gelatin and PBS were dissolved at a mass-to-volume ratio of 1:10 at 60°C. The mass ratio of methacrylic anhydride to gelatin was 5:

4. After the reaction was completed, 4 times the volume of PBS buffer was added for dilution.

3. The method for preparing the composite hydrogel for wound repair according to claim 1, characterized in that, In S2, 3.0 g of sodium periodate was dissolved in 80 mL of deionized water and then added to 320 mL of a 1.25% (w / v) dextran solution. The mixture was then reacted in the dark at 25 °C.

4. The method for preparing the composite hydrogel for wound repair according to claim 1, characterized in that, In S3, the amount of methacrylated gelatin added to deionized water is 3 wt%; the volume ratio of added hydroxyethyl methacrylate to deionized water is 2:5; and the amount of oxidized dextran added is 3 wt%.

5. The method for preparing the composite hydrogel for wound repair according to claim 1, characterized in that, In S3, methacrylamide gelatin is dissolved in deionized water at 60°C, cooled to room temperature, and hydroxyethyl methacrylate is added. The mixture is stirred until homogeneous, then heated to 50°C, and oxidized dextran is added. The mixture is stirred until completely dissolved to form a homogeneous solution.

6. The method for preparing the composite hydrogel for wound repair according to claim 1, characterized in that, In S5, the degassing process is carried out under an ultrasonic power of 300 W; the ultraviolet wavelength is 365 nm.

7. A composite hydrogel for wound repair, characterized in that, The composite hydrogel for wound repair is prepared according to the preparation method of any one of claims 1 to 6, and has a multi-level cross-linked structure, including a first network formed by dynamic cross-linking of ODex and GelMA, and a second network formed by HEMA and GelMA copolymer backbone and uniformly dispersed CuS nanoparticles under the action of ultraviolet light and photoinitiator.

8. The application of the composite hydrogel for wound repair as described in claim 7 in the preparation of wound dressings, characterized in that, When used, the wound dressing can be combined with near-infrared light irradiation to enhance the antibacterial effect through the synergistic effect of photothermal ablation and CuS nanoparticle-mediated sterilization.

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