Double-layer hydrogel dressing for diabetic wounds and application of double-layer hydrogel dressing

Abstract

The invention discloses a high-glucose response type double-layer hydrogel dressing for diabetic wounds and application of the high-glucose response type double-layer hydrogel dressing. The dressing is composed of an inner layer and an outer layer which are complementary in function, wherein the inner layer is mainly composed of polyvinyl alcohol, phenylboronic acid grafted silk fibroin and tannic acid, and a cross-linked network is formed through dynamic boric acid ester bonds and hydrogen bonds; the outer layer is mainly prepared from methacrylated hyaluronic acid, salvianolic acid B, polydimethylsiloxane, glycerol and sodium ethylparaben, and a stable framework is formed through photochemical crosslinking. The inner layer structure can respond to a high-glucose microenvironment of a wound and intelligently release tannic acid, so that the adhesion of the dressing is enhanced, and the anti-inflammatory and anti-oxidation effects are achieved; and the outer layer structure provides long-acting moisturizing, mechanical supporting and physical barrier functions and can release salvianolic acid B in a controlled manner to promote angiogenesis. The double-layer hydrogel structure disclosed by the invention realizes space-time drug delivery and targeted treatment at different stages in a diabetes wound healing process.

Description

Technical Field

[0001] This invention belongs to the field of skin medical materials technology, and more specifically, it is a high-glucose-responsive bilayer hydrogel that delivers drugs sequentially to different stages of diabetic wound healing to achieve anti-inflammatory and angiogenesis effects. Background Technology

[0002] The healing process of diabetic wounds becomes complex due to the long-term effects of high blood sugar levels. This biological process encompasses multiple aspects, including bacterial proliferation, increased inflammation, and impaired angiogenesis. High blood sugar levels provide favorable conditions for bacterial growth, leading to rapid bacterial proliferation in a high-sugar environment. Furthermore, the high-glycemic environment stimulates the release of inflammatory factors, exacerbating the inflammatory response. During the critical proliferative phase of wound healing, high blood sugar impairs vascular function, resulting in insufficient nutrient supply and consequently affecting skin tissue regeneration. Therefore, wound healing is a complex, progressive process that can be addressed through targeted treatment targeting inflammation, cell proliferation, and tissue remodeling.

[0003] Against this backdrop, hydrogel dressings, with their ability to mimic the properties of skin and soft tissue, have found widespread application in wound repair. By adjusting cross-linking methods and structures, hydrogels can meet diverse repair needs. However, existing hydrogel dressings have some limitations, particularly in the healing of diabetic wounds. In the field of diabetic wounds, functional hydrogels with antibacterial, anti-inflammatory, and antioxidant properties are predominantly used, and are designed with good adhesion, high extensibility, and biomimetic functions based on the skin application scenario. However, given the high blood sugar levels and complex changes during the healing process of diabetic wounds, the aforementioned traditional hydrogel dressings cannot adapt to the specific needs of different stages. Therefore, there is an urgent need to develop a novel hydrogel dressing that can respond to high blood sugar levels to adapt to the different stages of wound healing, switching between different functions for targeted treatment, while being safe, convenient, and ensuring maximum therapeutic effect. Summary of the Invention

[0004] This invention proposes a high-glucose-responsive bilayer hydrogel dressing to address the slow healing and high infection risk of diabetic wounds. Specifically, the inner layer of the hydrogel adheres tightly to the wound site, precisely releasing anti-inflammatory drugs in the high-glucose state of the wound to regulate the inflammatory phase. The outer layer forms a protective layer, resisting external pressure and deformation, and preventing bacterial invasion and infection. Simultaneously, the network structure of the outer layer loads angiogenesis-promoting drugs, which are gradually released during the wound healing proliferation phase, promoting angiogenesis and accelerating skin wound repair, thus providing a targeted treatment solution for wound healing in diabetic patients.

[0005] To achieve the above objectives, the components and their mass concentrations of the bilayer hydrogel dressing of the present invention are as follows: The core components of the inner hydrogel include 3wt%~8wt% phenylboronic acid grafted silk fibroin, 1wt%~3wt% polyvinyl alcohol, and 0.1wt%~0.2wt% tannic acid.

[0006] The core components of the outer hydrogel include 1 wt% to 4 wt% methacrylamide hyaluronic acid, 0.1 wt% to 0.2 wt% salvianolic acid B, 1 wt% to 3 wt% polydimethylsiloxane, 5 wt% to 20 wt% glycerol, and 0.01% to 0.1 wt% sodium ethylparaben.

[0007] Preferably, the bilayer hydrogel, by weight, comprises the following: inner layer hydrogel: 5 wt% phenylboronic acid grafted silk fibroin, 2 wt% polyvinyl alcohol, 0.1 wt% tannic acid, with the remainder being purified water. The outer layer hydrogel comprises the following: 3 wt% methacryloyl hyaluronic acid, 0.2 wt% salvianolic acid B, 2 wt% polydimethylsiloxane, 10 wt% glycerol, 0.1 wt% sodium ethylparaben, 0.2 wt% photoinitiator, with the remainder being purified water.

[0008] Preferably, the polydimethylsiloxane is one of hexamethyldisiloxane or octamethyltrisiloxane.

[0009] Preferably, the photoinitiator is I2959.

[0010] A method for preparing the bilayer hydrogel dressing as described above includes the following steps: S1: Preparation of phenylboronic acid-grafted silk fibroin: Silk fibroin was dissolved in PBS solution, followed by the addition of carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the silk fibroin solution, and thorough mixing. The pH of the solution was then adjusted, 4-carboxyphenylboronic acid was added, and the grafting reaction was carried out at 37°C. After the reaction, the phenylboronic acid-grafted silk fibroin was obtained by centrifugation and washing.

[0011] S2: Preparation of the inner hydrogel: First, polyvinyl alcohol is weighed into purified water and heated until fully dissolved. Then, phenylboronic acid-grafted silk fibroin and tannic acid are separately weighed and dissolved in purified water. Subsequently, both solutions are simultaneously added to a custom mold and mixed thoroughly to form the inner hydrogel.

[0012] S3: Preparation of methacrylamide hyaluronic acid: Hyaluronic acid was dissolved in purified water, and the pH of the solution was adjusted to 10. Methacrylic anhydride was then added dropwise. After reacting in the dark for 24 hours, ethanol was added to precipitate the hyaluronic acid, which was then separated. Methacrylamide hyaluronic acid was obtained by dialysis and freeze-drying.

[0013] S4: Preparation of the outer hydrogel: Methacrylamide hyaluronic acid, salvianolic acid B, polydimethylsiloxane, glycerol, sodium ethylparaben, and photoinitiator I2959 were weighed and dissolved in purified water to obtain a prepolymer solution. Finally, it was poured into the custom mold from step 2 and cured under ultraviolet light for 5 minutes to obtain a bilayer hydrogel.

[0014] The design principle of the high-sugar-responsive bilayer hydrogel prepared in this invention is as follows: the inner layer is mainly composed of borate ester bonds formed between polyvinyl alcohol and phenylboronic acid grafted silk fibroin, supplemented by hydrogen bonding between silk fibroin and tannic acid to form a β-sheet structure that strengthens the network cross-linking of the hydrogel. Phenylboronic acid grafted silk fibroin is a natural polymer material with excellent biocompatibility and biodegradability. The introduction of phenylboronic acid groups endows it with self-healing and environmental responsiveness. The borate ester bonds formed between phenylboronic acid grafted silk fibroin and polyvinyl alcohol can dynamically dissociate under high-sugar conditions, achieving controlled drug release. Tannic acid is a natural polyphenol compound with antibacterial, anti-inflammatory, and antioxidant properties. Tannic acid contains abundant phenolic groups, which can form ionic and hydrogen bonds with polymers. Among them, the hydrogen bonding between tannic acid and silk fibroin can form a β-sheet structure, and the bonding between tannic acid and the skin surface can increase adhesion. Therefore, the inner layer hydrogel adheres tightly to the wound, and under the influence of high sugar, releases tannic acid to exert an anti-inflammatory effect.

[0015] The outer layer is formed by chemical cross-linking of methacryloyl hyaluronic acid to create a three-dimensional network structure. Methacrylamide hyaluronic acid is a natural biomolecule with excellent biocompatibility. The hyaluronic acid, modified through double bonds to form a three-dimensional structure, not only resembles the extracellular matrix, mimicking the natural environment for cell growth and providing necessary support and protection, but also serves as a carrier for drug delivery systems, enabling controlled drug release. During the proliferative phase of wound healing, the proliferation of blood vessels helps provide tissues with more oxygen and nutrients, thereby promoting wound healing. Tanshinone B is a traditional Chinese medicine active substance with multiple pharmacological activities, including antibacterial, anti-fibrotic, and vascular protective effects. Tanshinone B can promote the proliferation and repair of endothelial cells and enhance the self-repair ability of blood vessels. Furthermore, polydimethylsiloxane and glycerol can alter the water loss properties of the hydrogel, improving its stability in air. Therefore, the outer hydrogel not only resists external compression and deformation but also forms a protective layer, isolating bacterial invasion and infection. More importantly, the release of Tanshinone B during the proliferative phase of wound healing promotes angiogenesis and accelerates skin tissue repair.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention provides the preparation and application of a bilayer hydrogel dressing for diabetic wound healing. The bilayer hydrogel consists of two layers with different functions: an inner layer that adheres tightly to the wound, and an outer layer that isolates the wound from bacterial invasion and infection, while simultaneously releasing different drugs for targeted treatment and accelerated skin tissue repair. Specifically, the inner hydrogel releases tannins in response to a high-sugar environment. Tannins play an anti-inflammatory and antioxidant role during the inflammatory phase of wound healing. The outer hydrogel releases salvianolic acid B during the proliferative phase of wound healing to promote angiogenesis and accelerate skin tissue repair. Therefore, the bilayer hydrogel dressing of this invention possesses excellent biocompatibility, water retention, antibacterial properties, anti-inflammatory effects, and promotes angiogenesis, cell proliferation, and the wound healing process. Attached Figure Description

[0017] Figure 1 The results show the antibacterial effects of co-incubating the hydrogels of Examples 1-2 and Comparative Example 1 on Staphylococcus aureus for 6 hours.

[0018] Figure 2 The cumulative release of tannic acid in the high-sugar solution in Example 1 is shown.

[0019] Figure 3 The effects of hydrogels from Examples 1-2 and Comparative Example 1 on cell proliferation capacity after treatment at different times are shown.

[0020] Figure 4 The effects of hydrogels in Examples 1-2 and Comparative Example 1 on the migration ability of endothelial cells were investigated.

[0021] Figure 5 The effects of hydrogels in Examples 1-2 and Comparative Example 1 on the tubular formation ability of endothelial cells were investigated. Detailed Implementation

[0022] To make the technical solution of the present invention clearer and more explicit, further explanation is provided in conjunction with specific embodiments.

[0023] Example 1 S1: To prepare the inner hydrogel, weigh 2.0 g of polyvinyl alcohol and add it to a 100 mL beaker containing 50 mL of purified water for swelling. Then, heat to 80 °C and stir in a water bath for 30 minutes to obtain a polyvinyl alcohol solution. Next, weigh 5.0 g of phenylboronic acid-grafted silk fibroin and 0.1 g of tannic acid into a 100 mL beaker, add 50 mL of purified water, and stir until completely dissolved. Use a syringe to draw up the above solutions separately, and then simultaneously inject the two syringes into a custom mold. Let it stand at room temperature for 30 minutes to obtain the inner hydrogel.

[0024] S2: To prepare the outer hydrogel, weigh 3.0 g of methacrylamide hyaluronic acid into a 200 mL beaker, add 100 mL of purified water, and stir until completely dissolved. Then, weigh 0.2 g of salvianolic acid B, 2.0 g of polydimethylsiloxane, 10.0 g of glycerol, and 0.1 g of sodium ethylparaben, and slowly add them to the methacrylamide hyaluronic acid solution while stirring thoroughly. After dissolving, add 0.2 g of photoinitiator I2959 and continue stirring for 30 minutes. Then, pour the prepolymer solution into the custom mold from S1, let it stand at room temperature for 10 minutes, and then transfer it to UV light for curing for 5 minutes to obtain the bilayer hydrogel.

[0025] Example 2 S1: To prepare the inner hydrogel, weigh 2.0 g of polyvinyl alcohol and add it to a 100 mL beaker containing 50 mL of purified water for swelling. Then, heat to 80 °C and stir in a water bath for 30 minutes. Next, weigh 8.0 g of phenylboronic acid-grafted silk fibroin and 0.1 g of tannic acid into a 100 mL beaker, add 50 mL of purified water, and stir until completely dissolved. Use a syringe to draw up the above solutions separately, and then simultaneously inject both syringes into a custom mold. Let it stand at room temperature for 30 minutes to obtain the inner hydrogel.

[0026] S2: To prepare the outer hydrogel, weigh 3.0 g of methacrylamide hyaluronic acid into a 200 mL beaker, add 100 mL of purified water, and stir until completely dissolved. Then, weigh 0.2 g of salvianolic acid B, 2.0 g of polydimethylsiloxane, 10.0 g of glycerol, and 0.1 g of sodium ethylparaben, and slowly add them to the methacrylamide hyaluronic acid solution while stirring thoroughly. After dissolving, add 0.2 g of photoinitiator I2959 and continue stirring for 30 minutes. Then, pour the prepolymer solution into the custom mold from S1, let it stand at room temperature for 10 minutes, and then transfer it to UV light for curing for 5 minutes to obtain the bilayer hydrogel.

[0027] Comparative Example 1 S1: To prepare the inner hydrogel, weigh 2.0 g of polyvinyl alcohol and add it to a 100 mL beaker containing 50 mL of purified water for swelling. Then, heat to 80 °C and stir in a water bath for 30 minutes. Next, weigh 8.0 g of phenylboronic acid-grafted silk fibroin into a 100 mL beaker, add 50 mL of purified water, and stir until completely dissolved. Use a syringe to draw up the above solutions separately, and then simultaneously inject both syringes into a custom mold. Let it stand at room temperature for 30 minutes to obtain the inner hydrogel.

[0028] S2: To prepare the outer hydrogel, weigh 3.0 g of methacrylamide hyaluronic acid into a 200 mL beaker, add 100 mL of purified water, and stir until completely dissolved. Then, weigh 2.0 g of polydimethylsiloxane, 10.0 g of glycerol, and 0.1 g of sodium ethylparaben and slowly add them to the methacrylamide hyaluronic acid solution while stirring thoroughly. After dissolving, add 0.2 g of photoinitiator I2959 and continue stirring for 30 minutes. Then, pour the prepolymer solution into the custom mold from S1, let it stand at room temperature for 10 minutes, and then transfer it to UV light for curing for 5 minutes to obtain the bilayer hydrogel.

[0029] Comparative Example 2 Weigh 2.0g of polyvinyl alcohol and add it to a 100mL beaker containing 50mL of purified water to allow it to swell. Then, heat the mixture to 80℃ and stir it in a water bath for 30 minutes. Next, weigh 8.0g of phenylboronic acid-grafted silk fibroin into a 100mL beaker, add 50mL of purified water, and stir until completely dissolved. Use a syringe to draw up the solutions separately, and then simultaneously inject both syringes into a custom mold. Allow the mixture to stand at room temperature for 30 minutes to obtain a monolayer hydrogel.

[0030] Comparative Example 3 Take 3.0 g of methacrylamide hyaluronic acid into a 200 mL beaker, add 100 mL of purified water and stir until completely dissolved. Then weigh 2.0 g of polydimethylsiloxane, 10.0 g of glycerol and 0.1 g of sodium ethylparaben and slowly add them to the methacrylamide hyaluronic acid solution while stirring thoroughly. After dissolving, add 0.2 g of photoinitiator I2959 and continue stirring for 30 minutes. Then pour the prepolymer solution into the custom mold in S1, let it stand at room temperature for 10 minutes, and then transfer it to UV light to cure for 5 minutes to obtain a monolayer hydrogel.

[0031] The performance evaluation of the bilayer hydrogel dressing of the present invention uses the hydrogel dressing described in the examples as the research object, and the specific experimental conditions are as follows: User experience test In this experiment, 15 healthy volunteers were selected for the testing phase. First, the inner forearms of both hands were cleaned. Four test areas (2cm × 2cm) were marked on the inner side of the left hand. Hydrogel dressings from Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were applied sequentially. The entire testing process was conducted in a strictly controlled temperature and humidity laboratory environment. Volunteers were required to remain seated, observe, and record the changes in their skin at different times.

[0032] Experimental Results: During use, none of the four hydrogel dressings caused allergic reactions and adhered closely to the skin without causing any tightness or discomfort. Compared to the double-layer hydrogel in Example 1, the single-layer hydrogel in Comparative Example 2 was slightly less flexible and prone to breakage. However, due to the presence of dynamic bonds, the hydrogel in Comparative Example 2 could self-heal and also had a certain degree of adhesion. On the other hand, the hydrogel in Comparative Example 3 performed the worst in terms of skin adhesion among the four hydrogels. Therefore, the hydrogel of the present invention will not cause harm to the skin during use, ensuring safety and comfort.

[0033] Antibacterial effect test Staphylococcus aureus, a common bacterium causing wound infections, was evaluated for its antibacterial properties through co-incubation with hydrogel. In the experiment, the hydrogel was first immersed in Staphylococcus aureus bacterial suspension and incubated with shaking at 37°C. After 12 hours of co-incubation, 50 μL of the bacterial suspension was diluted. The diluted suspension was then evenly spread onto agar plates and incubated overnight at 37°C. The following day, the morphology and number of bacterial colonies on the agar plates were observed, and the inhibition rate was calculated.

[0034] Experimental results: such as Figure 1 As shown, the hydrogels of this invention all exhibit excellent antibacterial effects. However, the antibacterial rate of Comparative Example 1 hydrogel was relatively low (94.5% ± 0.5%) because it was not loaded with tannic acid and salvianolic acid B. Therefore, the release of tannic acid and salvianolic acid B plays a crucial role in inhibiting the growth of bacteria causing wound infection.

[0035] High glucose responsive drug release behavior test Boronate bonds dynamically change in response to increased glucose concentration at the wound site, thus responding to the needs of the diabetic wound microenvironment. In the experiment, the hydrogel of Example 1 was first immersed in a glucose solution (11.1 mmol / L) and shaken uniformly in a 37°C incubator. Tannic acid content was measured at 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, and 24 h. The absorbance of tannic acid in the solution was measured at 275 nm using a UV spectrophotometer, and the cumulative release was calculated. The release amount of the hydrogel of Example 1 in PBS was used as a control to analyze the high glucose responsiveness of the hydrogel described in this invention.

[0036] Experimental results: such as Figure 2 As shown, in glucose solution, the amount of tannic acid released by the hydrogel of Example 1 was higher than that released in PBS solution. That is, the phenylboronic acid groups in the hydrogel preferentially bind to glucose, thereby promoting the release of tannic acid, and exhibiting high sugar responsiveness.

[0037] Cell proliferation capacity test In the process of skin wound healing, the proliferation of fibroblasts plays a crucial role in promoting tissue repair. In this experiment, fibroblasts (L929 cell line) were first seeded in 96-well culture plates. After the cells adhered, the hydrogel extraction solution of this invention was added. Subsequently, the culture plates were placed in a 37°C, 5% CO2 incubator, and cell proliferation was assessed using the CCK8 assay at 1, 3, and 5 days.

[0038] Experimental results: such as Figure 3 As shown, the hydrogel of this invention exhibits excellent biocompatibility, demonstrating no toxic side effects on cells. Further comparative analysis showed that, compared to the control group, the cell survival rate of the hydrogel group was significantly increased, promoting cell proliferation.

[0039] Endothelial cell migration ability test As wounds heal, angiogenesis promotes the growth of granulation tissue, thereby restoring normal skin function. Endothelial cell migration is one of the key steps in angiogenesis. In the experiment, endothelial cells were first seeded in 6-well culture plates. When the cell density reached 90%, uniformly wide incisions were made in each well using a pipette tip. Subsequently, detached cell debris was repeatedly rinsed off, and the hydrogel extraction solution of this invention was added. After co-culturing for 24 hours, the cell migration rate was observed.

[0040] Experimental results: such as Figure 4 As shown, compared to the control group, the hydrogel in Example 1 significantly promoted endothelial cell migration. In contrast, the hydrogel in Comparative Example 1 showed fewer cell migrations. This is because salvianolic acid B has an angiogenic effect, effectively stimulating endothelial cell proliferation, enhancing intercellular adhesion, and accelerating cell migration.

[0041] Endothelial cell tube-forming ability test Endothelial cell tubulation refers to the adhesion and arrangement of endothelial cells into tubular structures, forming a preliminary vascular network, which can visually reflect the ability of angiogenesis. In the experiment, pre-cooled Matrigel was first spread into 96-well culture plates, then placed in a 37°C, 5% CO2 incubator to allow the Matrigel to solidify. Next, endothelial cells and the hydrogel extract of this invention were added for co-culture, and the number of endothelial cell tubules was observed after 8 hours.

[0042] Experimental results: such as Figure 5 As shown, compared to the control group, the hydrogel in this example significantly promoted the number of tubes formed by endothelial cells during the tube formation process. In contrast, the hydrogel in Comparative Example 1 resulted in fewer tubes, shorter tube lengths, and weaker tube-forming ability. Therefore, the hydrogel described in this invention can exert a pro-angiogenic effect by promoting endothelial cell migration and tube formation.

[0043] In summary, the bilayer hydrogel dressing described in this invention offers excellent safety, ensuring it will not cause additional damage when applied to wounds. Its unique bilayer design greatly enriches the hydrogel's structural morphology and endows it with diverse functions, thus more flexibly adapting to the needs of various skin wounds. The inner layer structure incorporates a high-glucose response mechanism, enabling precise release of tannins at diabetic wound sites, thereby accelerating wound healing. Simultaneously, the hydrogel combines the angiogenesis-promoting ability of salvianolic acid B and loads it onto the outer network structure, achieving sequential drug release according to different healing stages during treatment, ensuring maximum therapeutic effect.

Claims

1. A high-sugar responsive bilayer hydrogel dressing, characterized in that, The inner layer is primarily composed of borate ester bonds between polyvinyl alcohol and phenylboronic acid grafted onto silk fibroin, supplemented by hydrogen bonds between silk fibroin and tannic acid to form a β-sheet structure that strengthens the hydrogel's network cross-linking. The high sugar responsiveness of the borate ester bonds facilitates the release of tannic acid, promoting treatment during the inflammatory phase of wound healing. The outer layer, formed by the chemical cross-linking of methacryloyl hyaluronic acid, provides cells with simulated survival conditions and is loaded with salvianolic acid B for time-dependent release, achieving corresponding treatment at different stages of wound healing. The composition and its mass concentration are as follows: Benzylboronic acid grafted fibroin 3wt%~8wt%, Polyvinyl alcohol 1wt%~3wt%, Tannic acid 0.1wt%~0.2wt%, Methacrylamide hyaluronic acid 1wt%~4wt%, Tanshinone B 0.1wt%~0.2wt%, Polydimethylsiloxane 1wt%~3wt%, Glycerin 5wt%~20wt%, Sodium ethylparaben 0.01wt%~0.1wt%, Photoinitiator 0.1wt%~0.25wt%, The remaining components are purified water.

2. The high-sugar responsive bilayer hydrogel dressing according to claim 1, characterized in that, The core components of the inner hydrogel include 5wt% phenylboronic acid grafted silk fibroin, 2wt% polyvinyl alcohol, and 0.1wt% tannic acid.

3. The high-sugar responsive bilayer hydrogel dressing according to claim 1, characterized in that, The core components of the outer hydrogel include 3wt% methacrylamide hyaluronic acid, 0.2wt% salvianolic acid B, 2wt% polydimethylsiloxane, 10wt% glycerin, and 0.1wt% sodium ethylparaben.

4. The high-sugar responsive bilayer hydrogel dressing according to claim 1, characterized in that, The polydimethylsiloxane is one of hexamethyldisiloxane or octamethyltrisiloxane.

5. The high-sugar responsive bilayer hydrogel dressing according to claim 1, wherein the photocrosslinking agent is I2959.

6. The method for preparing the high-sugar responsive bilayer hydrogel dressing according to claims 1-5, characterized in that, Includes the following steps: S1: To prepare the inner layer hydrogel, polyvinyl alcohol was weighed according to the specified ratio and added to a beaker for swelling. The mixture was then heated to 80°C and stirred in a water bath for 30 minutes to obtain a polyvinyl alcohol solution. Next, phenylboronic acid-grafted silk fibroin and tannic acid were weighed into another beaker, purified water was added, and the mixture was stirred until completely dissolved. The solutions were then drawn separately using syringes and simultaneously injected into a custom mold. After standing at room temperature for 30 minutes, the inner layer hydrogel was obtained. S2: To prepare the outer hydrogel, weigh methacrylamide hyaluronic acid into a beaker according to the proportion, add purified water and stir until completely dissolved. Then weigh salvianolic acid B, polydimethylsiloxane, glycerol and sodium ethylparaben and slowly add them to the methacrylamide hyaluronic acid solution and stir thoroughly. After dissolving, add photoinitiator I2959 and continue stirring for 30 minutes. Then pour the prepolymer into the custom mold in S1, let it stand at room temperature for 10 minutes, and then transfer it to UV light to cure for 5 minutes to obtain the bilayer hydrogel.

7. The application of a high-sugar responsive bilayer hydrogel dressing as described in any one of claims 1 to 5 in diabetic wounds.

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