MA@rGO / gelma composite hydrogel and preparation method and application thereof

Abstract

This invention discloses a MA@rGO / GelMA composite hydrogel, its preparation method, and its applications, belonging to the field of biomedical technology. The MA@rGO / GelMA composite hydrogel is a three-dimensional porous composite hydrogel formed by photoinitiation of a hydrogel matrix and functional nanoparticles dispersed in the hydrogel matrix. The hydrogel matrix is ​​methacrylamide gelatin (GelMA); the functional nanoparticles are silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGO NPs. The MA@rGO NPs of this invention endow the composite hydrogel with significant antibacterial properties, effectively reducing the risk of infection in diabetic wounds. This is because the silver nanoparticles (AgNPs) contained in the MA@rGO / GelMA composite hydrogel of this invention have broad-spectrum antibacterial activity.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, and in particular to a MA@rGO / GelMA composite hydrogel, its preparation method, and its application. Background Technology

[0002] Diabetes mellitus is a chronic metabolic disease characterized by long-term hyperglycemia, with a large and continuously increasing number of patients. Long-term hyperglycemia can induce multi-system complications, among which chronic diabetic wounds (such as diabetic foot ulcers) have a high incidence, long treatment period, and high risk of recurrence. In severe cases, they can develop into deep infections, gangrene, or even amputation, significantly impacting patients' quality of life and the social medical burden.

[0003] Normal wound healing typically involves stages such as hemostasis, inflammation, proliferation, and remodeling, and is precisely regulated by multiple factors including cells, cytokines, and the extracellular matrix. However, in the diabetic microenvironment, persistent high glucose levels lead to excessive production of reactive oxygen species (ROS) and enhanced oxidative stress, which in turn damages cell and tissue structure and delays the transition from the inflammatory phase to the proliferative phase. Simultaneously, impaired immune function makes wounds more susceptible to bacterial infection, which in turn amplifies the inflammatory response and ROS accumulation, creating a vicious cycle. Furthermore, diabetic patients often experience microvascular complications and local ischemia and hypoxia, resulting in impaired endothelial cell function and insufficient angiogenesis, leading to limited nutrient and oxygen transport, slow granulation tissue formation, and delayed epithelialization. Consequently, wounds often exhibit characteristics of prolonged non-healing or recurrent chronicity. Therefore, from a pathological perspective, simultaneously controlling bacterial infection, clearing excessive ROS, and promoting angiogenesis are key strategies for healing chronic diabetic wounds.

[0004] Currently, the clinical management of diabetic wounds mainly includes debridement, anti-infection treatment, negative pressure drainage, and dressing coverage. In recent years, hydrogel dressings have attracted attention due to their ability to maintain a moist healing environment, absorb exudate, adhere well, and load / deliver drugs or functional components. However, existing hydrogels still have limitations when used for chronic diabetic wounds: First, many products focus on physical coverage and moisturizing, lacking the ability to actively regulate key aspects such as infection, oxidative stress, and angiogenesis; second, although some functionalized hydrogels incorporate antibacterial or antioxidant components, they are difficult to simultaneously cover the multiple barriers of diabetic wounds; third, the stability and controllable release of active components remain limiting factors, affecting long-term sustained efficacy. Therefore, this paper aims to provide a functionalized hydrogel dressing that promotes diabetic wound healing through a multi-mechanism synergistic effect, combining effective antibacterial, ROS scavenging, and angiogenesis promotion effects, thereby improving the wound microenvironment and shortening the healing cycle of diabetic wounds. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies in the prior art by providing a MA@rGO / GelMA composite hydrogel.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned MA@rGO / GelMA composite hydrogel.

[0007] Another object of the present invention is to provide applications of MA@rGO / GelMA composite hydrogels.

[0008] The technical solution adopted to achieve the purpose of this invention is: A MA@rGO / GelMA composite hydrogel is a three-dimensional porous composite hydrogel formed by photoinitiation of a hydrogel matrix and functional nanoparticles dispersed in the hydrogel matrix; the hydrogel matrix is ​​methacrylamide gelatin (GelMA); and the functional nanoparticles are silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGO NPs.

[0009] In the above technical solution, the degree of substitution (DS) of the GelMA is 50% to 90%, preferably 60% to 85%; the mass volume fraction of the GelMA in the composite hydrogel is 5% to 20% (w / v), preferably 8% to 15% (w / v).

[0010] In the above technical solution, the concentration of the silver-manganese co-modified reduced graphene oxide nanocomposite in the composite hydrogel is 0.001-5 mg / mL, preferably 0.01-2 mg / mL, in order to achieve a balance between antibacterial / antioxidant effects and cell compatibility.

[0011] Another aspect of the present invention includes a method for preparing the MA@rGO / GelMA composite hydrogel, comprising the following steps: Step 1: Dissolve GelMA in buffer solution, then add photoinitiator LAP to obtain GelMA prepolymer solution; Step 2: Add silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGO to the GelMA prepolymer solution in Step 1, mix and disperse evenly to obtain the nanocomposite precursor system. Step 3: Irradiate the nanocomposite precursor system from Step 2 with light to crosslink and solidify it, thereby obtaining the composite hydrogel.

[0012] In the above technical solution, the mass-volume fraction of the photoinitiator is 0.01% to 1% (w / v), preferably 0.05% to 0.5% (w / v).

[0013] In the above technical solution, the preparation method of the silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGO includes the following steps: Step a: Add reduced graphene oxide (rGO) to water and disperse it by ultrasonication to obtain an rGO dispersion; Step b: Add silver nitrate solution to the rGO dispersion and stir to allow Ag to... + Adsorbed onto the surface of rGO, after pH adjustment, a reducing agent is added to initiate the reaction, thereby allowing Ag to... + In situ reduction to Ag nanoparticles and deposition / loading on the rGO surface yields Ag–rGO dispersion; Step c: After centrifuging and washing the Ag–rGO dispersion obtained in step b, disperse it in deionized water, adjust the pH, and add KMnO4 solution under stirring conditions to react so that manganese oxide MnOx is generated and loaded in situ on the rGO surface to obtain MA@rGO NPs.

[0014] In the above technical solution, in step a, the concentration of rGO is 0.1-5 mg / mL, preferably 1-2 mg / mL; the ultrasonic dispersion time is 0.5-2 h, preferably 1-2 h.

[0015] In the above technical solution, in step b, the stirring is carried out under light-protected conditions for 10 to 60 minutes.

[0016] In the above technical solution, in step b, Ag + The mass ratio of rGO to rGO is 0.1:1 to 10:1, preferably 0.5:1 to 5:1.

[0017] In the above technical solution, in step b, NaOH solution is used to adjust the pH to 8-10, preferably 8-9, and the pH is monitored during the reaction to ensure its stability.

[0018] In the above technical solution, in step b, the reducing agent is ascorbic acid solution, and the reaction is carried out at 50-90℃ for 0.5-6 h, preferably at 60-80℃ for 1-4 h; ascorbic acid and Ag + The molar ratio is 1:1 to 10:1, preferably 2:1 to 5:1.

[0019] In the above technical solution, in step c, the centrifugation conditions are 6000–20000 g for 5–20 min; the supernatant is washed 2–6 times with alternating deionized water and ethanol, preferably 3 times, until the supernatant is clear and its conductivity is close to that of blank (or Ag). + (The test result was negative) to remove residual ions and small molecules.

[0020] In the above technical solution, in step c, Ag–rGO is dispersed in deionized water at a concentration of 0.1–2 mg / mL, preferably 0.3–1 mg / mL; the pH is adjusted to 6–9, preferably 7–8.5; KMnO4 solution is added dropwise under stirring at 40–80℃, preferably 50–70℃, so that the final concentration of KMnO4 is 0.1–5 mM, preferably 0.5–2 mM; the reaction is carried out for 0.5–6 h, preferably 1–3 h; after the reaction is completed, unreacted components are removed by centrifugation, washing, and dialysis purification.

[0021] Another aspect of the invention includes the use of the MA@rGO / GelMA composite hydrogel in the preparation of dressings that promote the healing of diabetic wounds.

[0022] Another aspect of the invention includes a dressing comprising the aforementioned MA@rGO / GelMA composite hydrogel.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. The MA@rGO NPs of this invention endow the composite hydrogel with significant antibacterial properties, which can effectively reduce the risk of infection in diabetic wounds; this is because the silver nanoparticles (AgNPs) contained in the MA@rGO / GelMA composite hydrogel of this invention have broad-spectrum antibacterial effects, the mechanism of which mainly includes: (1) Silver nanoparticles can continuously release Ag + It binds to bacterial cell membrane proteins and enzymes, disrupting the cell membrane structure and causing leakage of cell contents; (2) Ag + It can bind to bacterial DNA, inhibiting its replication and transcription, thereby preventing bacterial proliferation; (3) Silver nanoparticles can also induce the generation of reactive oxygen species (ROS), which further cause oxidative damage to bacteria; 2. The manganese nanoparticle-related antioxidant effect of MA@rGO of the present invention can scavenge excess ROS, alleviate oxidative stress and help improve the inflammatory microenvironment; 3. The composite hydrogel of the present invention can form a moist healing environment on the wound and support cell adhesion, migration and proliferation. Combined with the microenvironment improvement effect, it can simultaneously achieve antibacterial and anti-infection, remove excess reactive oxygen species (ROS) to relieve oxidative stress and promote angiogenesis and tissue regeneration through multiple mechanisms, thereby improving the microenvironment of diabetic wounds, shortening the healing cycle and improving the healing quality. Attached Figure Description

[0024] Figure 1 This is a flowchart and a working principle diagram of the present invention.

[0025] Figure 2 This is an experiment for detecting reactive oxygen species (ROS).

[0026] Figure 3 Where A is the UV-Vis absorption spectrum of the DPPH scavenging experiment, B is the quantitative analysis of DPPH scavenging efficiency, and C is the ABTS. + The UV-Vis absorption spectrum of the scavenging experiment, where D represents ABTS. + Quantitative analysis of scavenging efficiency: E is the UV-Vis absorption spectrum of the TMB oxidation experiment, F is the quantitative analysis of the TMB oxidation experiment, G is the UV-Vis absorption spectrum of the SOD-like activity experiment, H is the quantitative analysis of the SOD-like activity experiment, **** indicates a highly significant difference compared with the blank group (P<0.0001).

[0027] Figure 4 In the figure, A shows representative colony formation images of Escherichia coli and Staphylococcus aureus in the control group, Gel group, and MA@rGO / Gel group; B shows the quantitative analysis of the corresponding bacterial survival rate; C shows the fluorescence microscopy image of Escherichia coli after AO / EB staining (scale bar = 500 μm); D shows the fluorescence microscopy image of Staphylococcus aureus after AO / EB staining (scale bar = 500 μm); **** indicates a highly significant difference compared with the blank group (P < 0.0001).

[0028] Figure 5 In this image, A shows representative images of the wound healing process on days 0, 10, and 20 for different treatment groups, and B is a schematic diagram of the wound closure process. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] In the following embodiments, HUVECs were purchased from the Cell Bank of the Chinese Academy of Sciences, model SCSP-5536 (immortalized strain); E. coli was purchased from Beijing Beina Chuanglian Biotechnology Research Institute (BNCC), model BNCC133264; and S. aureus was purchased from Beijing Beina Chuanglian Biotechnology Research Institute (BNCC), model BNCC186335.

[0031] Example 1 like Figure 1 As shown, a method for preparing an MA@rGO / GelMA composite hydrogel includes the following steps: Step 1: Add 1.0 g of GelMA to 6 mL of PBS and stir until dissolved and clear in a 50°C water bath. Add 10 mg of photoinitiator LAP and stir to obtain GelMA prepolymer solution (concentration 0.1% (w / v)). Step 2: Add 20 mg MA@rGO NPs to 1.0 g GelMA prepolymer solution, and make up the total volume to 10 mL with PBS. Vortex mix for 1 min, and then sonicate for 5 min to obtain the nanocomposite precursor system.

[0032] The preparation method of the MA@rGO NPs specifically includes the following steps: Step a: Add 15.0 mg of reduced graphene oxide (rGO) to deionized water and bring the volume to 10 mL (rGO concentration 1.5 mg / mL); then sonicate for 90 min under ice bath conditions to obtain a uniform rGO dispersion.

[0033] Step b: Add 8.49 mg of silver nitrate directly to 10 mL of the rGO dispersion obtained in step a (to achieve a final silver nitrate concentration of 5 mM), and magnetically stir for 30 min in the dark to promote Ag... + Ag nanoparticles were slowly added to the rGO surface to adjust the pH to 8.5. The mixture was stirred for 10 min, and then 26.4 mg of ascorbic acid (VC) and 1 mL of deionized water were slowly added. The mixture was placed in a 70 °C water bath for 3 h to reduce the nanoparticles in situ and deposit / load them onto the rGO surface, resulting in an Ag–rGO reaction solution. The Ag–rGO reaction solution was centrifuged at 14000 rpm for 10 min, the supernatant was discarded, and the mixture was resuspended in deionized water. The mixture was washed twice with deionized water and once with anhydrous ethanol. Finally, the mixture was resuspended in deionized water and brought to a final volume of 30 mL to obtain an Ag–rGO dispersion with a concentration of 0.5 mg / mL.

[0034] Step c: The Ag–rGO dispersion obtained in step b was collected by centrifugation, resuspended in deionized water, and brought to a final volume of 0.5 mg / mL Ag–rGO and a total volume of 10 mL (i.e., the total amount of Ag–rGO in the system was 5.0 mg). The system was then preheated in a 60℃ water bath with magnetic stirring (approximately 500 rpm) for 10 min to obtain the Ag–rGO system. 2.37 mg of potassium permanganate (KMnO4) was dissolved in deionized water to prepare a 1.5 mM KMnO4 solution (10 mL), which was then added dropwise to the Ag–rGO system to carry out the reaction, bringing the final concentration of KMnO4 in the reaction system to 1.5 mM. During the reaction, the pH of the system was adjusted dropwise using 0.01 mol / L NaOH / HCl and maintained at 7.5 ± 0.2. The reaction was continued at 60℃ for 2 h, resulting in a 5 mg / mL dispersion of composite nanomaterials loaded with manganese components. The resulting dispersion was centrifuged at 14,000 rpm for 10 min, and the supernatant was discarded. The mixture was then resuspended in deionized water and washed three times to remove unreacted components. Finally, the mixture was resuspended in PBS and brought to the required volume to obtain a MA@rGONPs dispersion with a concentration of 5 mg / ml.

[0035] Step 3: Inject the nanocomposite precursor system into the mold and irradiate it with a 405 nm light source for 60 s for cross-linking and curing to form MA@rGO / GelMA composite hydrogel, denoted as MA@rGO / Gel.

[0036] Depend on Figure 1 It is known that MA@rGO / Gel hydrogel systematically improves the pathological microenvironment of diabetic wounds through multiple synergistic mechanisms: on the one hand, the silver nanoparticles in the hydrogel can exert a broad-spectrum antibacterial effect, inhibit bacterial colonization, reduce the risk of wound infection, and prevent infection from further aggravating the inflammatory response; on the other hand, the manganese-based antioxidant effect of MA@rGO can efficiently remove excess ROS in the wound, alleviate oxidative stress, directly inhibit the continuous activation of chronic inflammation, and thus downregulate the expression of pro-inflammatory factors such as IL-6 and TNF-α, breaking the vicious cycle of continuous amplification of inflammation.

[0037] With the improvement of the inflammatory microenvironment, the three-dimensional network structure of the hydrogel provides a suitable moist healing environment for cells, supporting cell adhesion, migration and proliferation. It can effectively reverse the impaired function of fibroblasts in diabetic wounds and restore their ability to proliferate and synthesize extracellular matrix. At the same time, the relief of inflammation and reduction of oxidative stress also relieve the inhibition of vascular endothelial cells, significantly promote angiogenesis, improve the hypoxic state of the wound, and provide sufficient nutrition and oxygen supply for tissue repair.

[0038] Ultimately, the hydrogel systematically addresses key pathological issues in diabetic wounds, such as persistent chronic inflammation, poor angiogenesis, and fibroblast dysfunction, through its synergistic effects of antibacterial and anti-infection, antioxidant and anti-inflammatory properties, as well as its ability to promote angiogenesis and tissue regeneration. This effectively shortens the healing cycle and improves the quality of wound healing.

[0039] Application Example 1 Antioxidant performance evaluation of MA@rGO / GelMA composite hydrogel DCFH-DA: Human umbilical vein endothelial cells (HUVECs) were used to detect intracellular reactive oxygen species (ROS). After cell adhesion, cells were pretreated with 0.1 mM H2O2 for 5 h to induce oxidative stress. The H2O2 was then discarded, and the cells were gently washed with PBS. Three groups were set up: one control group and the other two groups were co-incubated with a hydrogel for 24 h. The hydrogels included GelMA hydrogel (Gel) and the MA@rGO / GelMA composite hydrogel obtained in the previous example. After co-incubation, cells were stained with probes according to the DCFH-DA kit instructions. After washing with PBS, fluorescence intensity was observed and detected using a laser confocal microscope. Fluorescence intensity was positively correlated with intracellular ROS levels. The scavenging effect of different hydrogels on intracellular ROS was evaluated by comparing the fluorescence signal intensity of the three groups. Figure 2 As shown, compared with the control group and the GelMA hydrogel group, the fluorescence intensity of the MA@rGO / GelMA composite hydrogel group was significantly reduced, indicating that it has a stronger scavenging effect on intracellular ROS. This is because the antioxidant effect of manganese nanoparticles can scavenge excess ROS, alleviate oxidative stress and help improve the inflammatory microenvironment.

[0040] Extracts of GelMA hydrogel and the MA@rGO / GelMA composite hydrogel from the examples were prepared separately: Both hydrogels were cut into small pieces, and PBS was added at a solid-liquid ratio of 0.2 g / mL. The mixtures were incubated at 37°C for 24 h. The supernatant was collected and filtered through a 0.22 μm filter membrane to obtain the hydrogel extracts. An equal volume of PBS was used as the control extract for the hydrogel-free group. The antioxidant capacity of the above extracts was tested using the following parameters.

[0041] DPPH free radical scavenging experiment: Prepare a 0.1 mM DPPH ethanol solution. Mix the three extracts with the DPPH solution at a volume ratio of 1:1 (e.g., 1.0 mL of each), incubate at room temperature in the dark for 30 min, and then measure the absorbance at 517 nm. Calculate the DPPH scavenging rate using the following formula: Scavenging rate (%) = ( A 0 A s ) / A0 ×100%, of which A 0 The absorbance is for the blank control. A s The absorbance after treatment with the extract of GelMA hydrogel or the MA@rGO / GelMA composite hydrogel of the example.

[0042] ABTS + Free radical scavenging experiment: 7 mM ABTS + The solution was mixed with 2.45 mM K2S2O8 solution at a volume ratio of 1:1 and reacted at room temperature in the dark for 12–16 h to generate ABTS. + Stock solution; dilute the stock solution with PBS to an absorbance of 0.70 ± 0.05 ABTS at 734 nm. + Working solution. Take the extracts from each group and mix them with ABTS. + The working solutions were mixed at a volume ratio of 1:9, reacted at room temperature for 6 min, and the absorbance was measured at 734 nm. The ABTS was then calculated using the formula described above. + Clearance rate.

[0043] SOD scavenging experiment: Superoxide anion (O2• - The test kit evaluates the O2• of the extract. - Scavenging ability. Prepare the reaction system according to the kit instructions, adding the same volume of each extract to the reaction system (e.g., 10% of the total reaction volume). After reacting within the specified time, measure the absorbance and calculate O2• according to the kit's calculation method. - Clearance rate.

[0044] TMB colorimetric inhibition assay: TMB working solution was prepared according to the TMB kit instructions. After adding H2O2 to initiate color development, the extraction solutions of each group were added. The reaction was allowed to proceed at room temperature for 10 min, and the absorbance was measured at 652 nm. A system with an equal volume of PBS was used as a blank control. The results of the above four tests (such as...) Figure 3 The comprehensive evaluation showed that the MA@rGO / GelMA hydrogel extract had significant advantages in antioxidant and free radical scavenging compared with the GelMA group and the control group. This is because the antioxidant effect of manganese nanoparticles can remove excess ROS, alleviate oxidative stress and help improve the inflammatory microenvironment.

[0045] Application Example 2 Evaluation of the antibacterial properties of MA@rGO / GelMA nanocomposite hydrogel dressing Antibacterial performance test (plate count method). *Escherichia coli* (E. coli) and *Staphylococcus aureus* (S. aureus) were selected as representative Gram-negative bacteria and compared with Gram-positive bacteria in the antibacterial experiment. The bacteria were inoculated into liquid culture medium and cultured with shaking until the logarithmic growth phase. The bacterial suspension concentration was adjusted to 1 × 10⁻⁶. 8 CFU / mL, and further diluted to 1×10 6 Three groups were set up, with one group serving as a control and the other two groups containing 2 mL of different hydrogels. The groups were incubated under sterile conditions at 37°C for 24 h. The hydrogels used were GelMA hydrogels or the MA@rGO / GelMA composite hydrogel obtained in the previous examples. After co-incubation, each mixture was serially diluted, and an appropriate amount of the diluted solution was evenly spread on solid agar plates. After incubation at 37°C for 24 h, photographs were taken and the colony counts (CFU) were counted. The bacterial survival rate / inhibition rate of each group was calculated based on the colony count results to quantitatively evaluate the antibacterial effect of the MA@rGO / GelMA composite hydrogel against *E. coli* and *S. aureus*. Figure 4 China A and Figure 4 As shown in Figure B, compared with the blank group and the GelMA hydrogel group, the survival rates of Escherichia coli and Staphylococcus aureus were significantly reduced after treatment with MA@rGO / GelMA.

[0046] Antibacterial performance test (AO / EB live / dead staining method). Following the AO / EB staining kit instructions, *E. coli* and *S. aureus* were stained, and bacterial survival was observed using an inverted fluorescence microscope. Live bacteria showed green fluorescence, while dead bacteria showed red fluorescence. The bactericidal effect of the material was qualitatively verified by comparing the differences in green / red fluorescence distribution among different groups. Figure 4 C and Figure 4 As shown in D, the results of the live / dead staining experiment were consistent with the plate counting data, further confirming the excellent antibacterial effect of MA@rGO / Gel.

[0047] Application Example 3 Application of MA@rGO / GelMA composite hydrogel in promoting the healing of diabetic skin wounds A diabetic mouse model was established by targeting and destroying pancreatic β cells with streptozotocin (STZ). Eight-week-old male C57BL / 6 mice were selected, fasted for 8 hours, and then intraperitoneally injected with STZ at a dose of 75 mg / kg for two consecutive days. Fasting blood glucose was measured 3 days after injection; mice with a fasting blood glucose level consistently >11.1 mmol / L were considered to have successfully established a diabetic model. The 18 successfully modeled mice were randomly divided into three groups of six each. The diabetic model mice were anesthetized, and their back hair was shaved. After routine disinfection, a circular full-thickness skin defect with a diameter of 8 mm was prepared on the back. The wound was treated with hydrogel-free (Control group), GelMA hydrogel group, and MA@rGO / GelMA composite hydrogel, respectively. The hydrogel was ensured to fully adhere to the wound surface and was changed every 2 days during the treatment period. Wound photographs were taken on days 0, 10, and 20 after treatment. ImageJ software was used to quantitatively analyze the wound area, calculate the changes in wound area and healing rate at each time point, and evaluate the promoting effect of different hydrogels on the healing of diabetic wounds.

[0048] The healing process of diabetic wounds, such as Figure 5 As shown, the wounds in all three groups contracted over time. The control group had the lowest wound healing rate and showed signs of scab formation. The MA@rGO / GelMA composite hydrogel group exhibited significantly faster wound contraction and the highest healing rate. These results indicate that the MA@rGO / GelMA nanocomposite hydrogel has a better healing-promoting effect than the other two groups. This is because the composite hydrogel can create a moist healing environment on the wound surface and support cell adhesion, migration, and proliferation. Combined with its microenvironment-improving effects, it simultaneously achieves antibacterial and anti-infection effects, scavenges excess reactive oxygen species (ROS) to alleviate oxidative stress, and promotes angiogenesis and tissue regeneration through multiple synergistic mechanisms. This improves the microenvironment of diabetic wounds, shortens the healing cycle, and enhances healing quality.

[0049] 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 MA@rGO / GelMA composite hydrogel, characterized in that, The MA@rGO / GelMA composite hydrogel is a three-dimensional porous composite hydrogel formed by photoinitiation of a hydrogel matrix and functional nanoparticles dispersed in the hydrogel matrix; the hydrogel matrix is ​​methacrylamide gelatin (GelMA); and the functional nanoparticles are silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGO NPs.

2. The MA@rGO / GelMA composite hydrogel according to claim 1, characterized in that, The degree of substitution of the GelMA is 50% to 90%; the mass-volume fraction of the GelMA in the composite hydrogel is 5% to 20% (w / v).

3. The MA@rGO / GelMA composite hydrogel according to claim 1, characterized in that, The concentration of the silver-manganese co-modified reduced graphene oxide nanocomposite in the composite hydrogel is 0.001–5 mg / mL.

4. The method for preparing the MA@rGO / GelMA composite hydrogel according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Dissolve GelMA in buffer solution, then add photoinitiator LAP to obtain GelMA prepolymer solution; Step 2: Add silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGONPs to the GelMA prepolymer solution in Step 1, mix and disperse evenly to obtain the nanocomposite precursor system. Step 3: Irradiate the nanocomposite precursor system from Step 2 with light to crosslink and solidify it, thereby obtaining the composite hydrogel.

5. The preparation method according to claim 4, characterized in that, The photoinitiator has a mass-volume fraction of 0.01% to 1% (w / v).

6. The preparation method according to claim 4, characterized in that, The preparation method of the silver-manganese co-modified reduced graphene oxide nanocomposite MA@rGO NPs includes the following steps: Step a: Add reduced graphene oxide to water and disperse by ultrasonication to obtain rGO dispersion; Step b: Add silver nitrate solution to the rGO dispersion and stir to allow Ag to... + Adsorbed onto the surface of rGO, after pH adjustment, a reducing agent is added to initiate the reaction, thereby allowing Ag to... + In situ reduction to Ag nanoparticles and deposition / loading on the rGO surface yields Ag–rGO dispersion; Step c: After centrifuging and washing the Ag–rGO dispersion obtained in step b, disperse it in deionized water, adjust the pH, and add KMnO4 solution under stirring conditions to react so that manganese oxide MnOx is generated and loaded in situ on the rGO surface to obtain MA@rGONPs.

7. The preparation method according to claim 6, characterized in that, In step a, the concentration of rGO is 0.1–5 mg / mL; the ultrasonic dispersion time is 0.5–2 h.

8. The preparation method according to claim 6, characterized in that, In step b, the stirring is carried out under light-protected conditions for 10 to 60 minutes. In step b, Ag + The mass ratio of rGO to rGO is 0.1:1 to 10:1; In step b, NaOH solution is used to adjust the pH to 8-10, and the pH is monitored during the reaction to ensure its stability. In step b, the reducing agent is ascorbic acid solution, and the reaction is carried out at 50–90°C for 0.5–6 h; ascorbic acid reacts with Ag + The molar ratio is 1:1 to 10:1; In step c, the centrifugation conditions are 6000–20000 g for 5–20 min; and the centrifugation is performed by alternating washing with deionized water and ethanol 2–6 times. In step c, Ag–rGO is dispersed in deionized water at a concentration of 0.1–2 mg / mL; the pH is adjusted to 6–9; KMnO4 solution is added dropwise under stirring at 40–80°C to achieve a final KMnO4 concentration of 0.1–5 mM, and the reaction is carried out for 0.5–6 h; after the reaction is completed, unreacted components are removed by centrifugation, washing, and dialysis purification.

9. The use of the MA@rGO / GelMA composite hydrogel as described in any one of claims 1 to 3 in the preparation of dressings that promote the healing of diabetic wounds.

10. A dressing, characterized in that, Includes the MA@rGO / GelMA composite hydrogel as described in any one of claims 1 to 3.

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