Bio-based hydrogel adhesive bandage and preparation method thereof

Abstract

The invention relates to the technical field of medical dressings, and discloses a bio-based hydrogel adhesive bandage and a preparation method thereof.The bio-based hydrogel adhesive bandage comprises a main hydrogel layer, an interface shear response layer and a backing layer, and a precursor mixed solution of the main hydrogel layer is prepared from, by weight, 350-550 parts of OP-N mother liquor, 350-650 parts of SPI mother liquor, 100-200 parts of water, 100-200 parts of water and 100-200 parts of water; the OP-N mother liquor is prepared from the following components in parts by weight: 300 to 700 parts of OP mother liquor, 0.5 to 8.0 parts of citric acid, 0.5 to 6.0 parts of hydroxylamine acetate and 0.2 to 8.0 parts of NaOH with the concentration of 1 mol / L. The interface shear response layer containing tannic acid and a buffer salt system is arranged on the surface of the main body hydrogel layer, so that the adhesive bandage can form a gel structure with relatively high shear resistance at an interface after being in contact with wound exudate, and the interface stability between gel and a wound is effectively improved under the action of gravity; the phenomena of migration and displacement of the hydrogel in the use process are obviously reduced.

Description

Technical Field

[0001] This invention relates to the field of medical dressing technology, specifically to a bio-based hydrogel wound dressing and its preparation method. Background Technology

[0002] Band-aids are medical dressings used to cover skin wounds, isolate them from the external environment, and provide suitable conditions for wound healing. They are widely used in cases of trauma, postoperative incisions, and chronic wounds. During use, band-aids typically need to possess a certain degree of adherence and flexibility to adapt to the shape changes of different parts of the body, while also being able to absorb wound exudate and maintain the stability of the local wound environment. With increasing demands for biocompatibility and environmental friendliness, the use of bio-based materials derived from natural resources, such as polysaccharides and proteins, to prepare band-aids has gained increasing attention. These materials have clear sources and good biocompatibility in both in vivo and in vitro applications, making them suitable for dressing products that come into direct contact with wounds.

[0003] Existing bio-based hydrogel wound dressings typically achieve wound coverage and protection by forming a hydrogel layer combined with a backing layer. During application, they primarily rely on the adhesive properties of the gel itself or external fixation methods to maintain positional stability. However, in practical use, when there is exudate on the wound or the application site is subjected to gravity, a wetting interface easily forms between the gel layer and the wound. This reduces the interface's shear resistance, making the hydrogel wound dressing prone to migration or displacement during use, affecting the stability of the application position and consequently negatively impacting the wound coverage effect. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a bio-based hydrogel wound dressing and its preparation method, solving the problem that hydrogel wound dressings are prone to migration or displacement during use, affecting the stability of the application position.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a bio-based hydrogel wound dressing and its preparation method, comprising a main hydrogel layer, an interfacial shear response layer, and a backing layer. The precursor mixture of the main hydrogel layer comprises the following raw materials in parts by weight: 350–550 parts of OP-N mother liquor and 350–650 parts of SPI mother liquor. The OP-N mother liquor is composed of 300–700 parts of OP mother liquor, 0.5–8.0 parts of citric acid, 0.5–6.0 parts of hydroxylamine acetate, and 0.2–8.0 parts of 1mol / L NaOH. The OP mother liquor comprises 900–980 parts deionized water, 20–100 parts pullulan, sodium periodate in a mass ratio of 0.02–0.18:1 to pullulan, and ethylene glycol in a mass ratio of 0.3–1.2:1.0 to sodium periodate. The SPI mother liquor comprises 850–980 parts deionized water, 20–150 parts soy protein isolate, and 0.2–6.0 parts 1 mol / L NaOH. The interfacial shear response layer coating solution comprises the following raw materials in parts by weight: 145–295 parts deionized water, 0.3–2.0 parts sodium dihydrogen phosphate, 0.1–1.5 parts tannic acid, and 0.05–2.0 parts 1 mol / L NaOH or 0.05–2.0 parts 1 mol / L HCl. The backing layer is a PLA moisture-permeable membrane.

[0006] By employing the above technical solution, a layered combination of a main hydrogel layer formed from oxidized pullulan and soy protein isolate with an interfacial shear-responsive layer containing tannic acid and sodium dihydrogen phosphate is achieved. This allows the main hydrogel layer to maintain a continuous gel structure while simultaneously forming an interfacial layer structure with shear-responsive characteristics on its wound-contact side. Under the influence of wound exudate, this interfacial shear-responsive layer participates in the construction of the interfacial structure, thereby improving the interfacial stability between the main hydrogel layer and the wound and reducing the possibility of overall migration or displacement under gravity and exudate wetting conditions. Simultaneously, the OP-N mother liquor, modified by oxidizing pullulan and introducing citric acid and hydroxylamine acetate, is incorporated into the main hydrogel layer, and combined with soy protein isolate... The separation of proteins constructs a cross-linked network structure, enabling the gel to undergo gradual network changes during use, reducing rapid local structural damage. This minimizes the concentration of low-molecular-weight components generated during degradation in the wound area, thus reducing their adverse effects on wound tissue. Furthermore, the interfacial shear-responsive layer and the main hydrogel layer are integrated into a single gel structure through coating and static integration. This achieves structural synergy without relying on additional external adhesives, ensuring both adhesion and structural stability during application. The backing layer uses a PLA breathable membrane, which, when combined with the gel structure, provides necessary moisture permeability channels to the wound while maintaining the integrity of the gel structure, making it suitable for various wound dressing application scenarios.

[0007] Preferably, a method for preparing a bio-based hydrogel wound dressing includes the following steps: S1. Prepare OP mother liquor; S2. Citric acid and hydroxylamine acetate (AOA) were added to the OP mother liquor for immobilization reaction. After purification and immobilization adjustment, the OP-N mother liquor was prepared. S3. Dissolve soy protein isolate in deionized water and adjust the pH to prepare SPI mother liquor; S4. Prepare the precursor mixture of the main hydrogel layer by mixing OP-N mother liquor, SPI mother liquor and deionized water in sequence. After pH adjustment, degassing and casting, the main hydrogel layer gel blank is obtained. S5. Prepare an interfacial shear response layer coating solution containing tannic acid, apply it to the wound contact side of the main hydrogel layer gel blank and let it stand to integrate to form a gel structure. S6. The PLA breathable membrane is laminated onto the non-wound side of the integrated gel structure, and after post-processing, the finished product is obtained.

[0008] By employing the above technical solution, OP mother liquor is prepared sequentially, followed by OP-N mother liquor via citric acid and hydroxylamine acetate immobilization reaction. SPI mother liquor is then prepared separately. The OP-N mother liquor, SPI mother liquor, and deionized water are then mixed sequentially to form a precursor mixture for the main hydrogel layer, which is then cast into shape. This allows pullulan oxide and soy protein isolate to form a continuous gel structure within the main hydrogel layer. Furthermore, by applying a tannic acid-containing interfacial shear-responsive layer coating solution to the wound-contact side of the main hydrogel layer gel blank and allowing it to integrate, the interfacial shear-responsive layer and the main hydrogel layer form an integrated gel structure. This results in a layered structure with shear-responsive characteristics at the wound interface during use. This process helps improve the interfacial stability of the main hydrogel layer under the influence of gravity and wound exudate, reducing the possibility of migration or displacement. Simultaneously, the preparation of the OP-N mother liquor involves the immobilization and modification of pullulan oxide, which participates in the formation of the main hydrogel layer. This ensures that the main hydrogel layer undergoes primarily overall gel structure changes during use, reducing rapid local structural damage and thus decreasing the likelihood of low-molecular-weight components accumulating in the wound area during degradation. Finally, by laminating a PLA breathable membrane onto the non-wound side of the integrated gel structure, a backing layer structure is formed without altering the integrity of the gel structure, meeting the requirements for structural support and breathability during wound dressing application.

[0009] Preferably, in step S1, the step of preparing the OP mother liquor is as follows: Add deionized water to the reaction vessel, add pullulan, and stir for 0.5–4 h at 4–25 °C and 200–800 rpm until completely dissolved to obtain polysaccharide mother liquor; Adjust the temperature of the polysaccharide mother liquor to 4–20℃, then add sodium periodate, and react in the dark at 4–20℃ and 200–600 rpm for 0.5–6 hours. Add ethylene glycol to the reaction solution and stir for 10–60 min at 4–20°C and 200–600 rpm to terminate the reaction. The reaction solution was dialyzed at 4–25℃ for 12–48 h, with water changes 4–12 times, to obtain the OP solution; The OP solution was concentrated under reduced pressure to a solid content of 4–10 wt% to obtain the OP mother liquor.

[0010] By employing the above technical solution, pullulan is dissolved in deionized water to form a polysaccharide mother liquor. Sodium periodate is then introduced under controlled temperature conditions to induce a light-protected reaction, causing the pullulan molecules to oxidize and introducing reactive functional groups into the polysaccharide molecular structure. Subsequently, ethylene glycol is added to terminate the reaction, and dialysis is performed to remove unreacted substances and low-molecular-weight byproducts, resulting in an OP solution with a defined composition. Based on this, the solution is concentrated under reduced pressure and the solid content is adjusted to obtain an OP mother liquor for subsequent reactions. This OP mother liquor, when mixed with other components to form the main hydrogel layer, can serve as a polysaccharide precursor with a defined structure and controllable reaction, contributing to the formation of a continuous and stable gel structure in the main hydrogel layer and providing the foundation for subsequent gel structure changes.

[0011] Preferably, in step S2, the immobilized reaction, after purification and immobilized formulation, includes the following steps: Add citric acid and hydroxylamine acetate to the OP mother liquor, stir for 10–60 min at 20–35℃ and 200–600 rpm, and then add 0.2–8.0 parts by weight of 1 mol / L NaOH to adjust the pH to 6.0–7.2. The mixture was reacted at 35–65℃ and 100–300 rpm for 0.5–8 h. The reaction solution was dialyzed at 4–25℃ for 6–24 h with water changes 3–8 times to obtain OP-N solution; The OP-N solution was adjusted to a solid content of 6–12 wt% to obtain the OP-N mother liquor.

[0012] By adopting the above technical solution, citric acid and hydroxylamine acetate are added to the OP mother liquor and stirred under controlled conditions. Simultaneously, the pH of the system is adjusted, allowing citric acid and hydroxylamine acetate to participate in the immobilization reaction of polysaccharide molecules in the OP mother liquor, forming a modified polysaccharide system. Subsequently, the reaction is continued under set conditions, and the reaction solution is dialyzed to remove unreacted low-molecular-weight substances, resulting in a well-defined OP-N solution. The solid content is then adjusted to obtain the OP-N mother liquor, enabling it to participate in the construction of the gel structure in the form of modified polysaccharides during the subsequent formation of the main hydrogel layer. This ensures that the structural changes of the main hydrogel layer are primarily due to overall changes in the gel network, reducing the possibility of rapid changes in local structures and providing a foundation for mitigating degradation-related adverse effects during use.

[0013] Preferably, in step S3, the preparation of the SPI mother liquor includes the following steps: Deionized water and soy protein isolate were mixed and stirred at 20–50°C and 300–1000 rpm for 0.5–3 h until completely dissolved. 0.2–6.0 parts by weight of 1 mol / L NaOH were added to adjust the pH to 6.6–7.4 to obtain the SPI mother liquor.

[0014] By adopting the above technical solution, soy protein isolate is dissolved in deionized water and a homogeneous solution is formed under stirring conditions. At the same time, sodium hydroxide is added to adjust the pH of the system, so that the soy protein isolate exists stably in a dissolved state, resulting in a well-defined SPI mother liquor. This allows the SPI mother liquor to participate uniformly in the construction of the gel structure as protein components when it is subsequently mixed with OP-N mother liquor to form the main hydrogel layer, ensuring the continuity and consistency of protein distribution in the main hydrogel layer.

[0015] Preferably, in step S4, obtaining the main hydrogel layer gel preform includes the following steps: First, add SPI mother liquor to the mixing container. Under stirring conditions of 200–500 rpm, slowly add OP-N mother liquor over a period of 5–20 min. Continue stirring at 200–500 rpm for 3–20 min. Add 1 mol / L NaOH to adjust the pH of the mixture to 6.6–7.4; The mixture was degassed at 15–30 °C and −0.06 to −0.095 MPa for 2–20 min. The degassed mixture is poured into a mold, and the wet film thickness is controlled at 1.5–5.0 mm. The mixture is allowed to stand at 10–30℃ for 3–60 min to form a gel, thus obtaining the main hydrogel layer gel preform.

[0016] By adopting the above technical solution, the SPI mother liquor is first added to the mixing container and the OP-N mother liquor is slowly added under stirring conditions. The two mother liquors are gradually mixed during controlled stirring, which is conducive to the formation of a uniform precursor mixture state between the OP-N mother liquor and the SPI mother liquor in the system. Subsequently, the pH of the mixture is adjusted to bring the system into a suitable range for the formation of a gel structure. The gas introduced during the mixing process is removed by degassing treatment to keep the resulting mixture continuous. The degassed mixture is then cast into a mold and allowed to stand to form a gel, resulting in a main hydrogel layer gel preform with an integral continuous structure. This allows the main hydrogel layer to exist in the form of an integral gel structure, providing a stable structural basis for the subsequent coating and integration of the interface shear response layer. This is beneficial for the main hydrogel layer to maintain structural integrity during use and participate in the formation of an integrated gel structure.

[0017] Preferably, in step S5, the step of preparing the interfacial shear response layer coating solution containing tannic acid is as follows: Deionized water, sodium dihydrogen phosphate, and tannic acid were mixed and stirred at 20–30°C and 200–600 rpm for 10–60 min. 1 mol / L NaOH was added to adjust the pH to 6.8–7.4 to obtain the interfacial shear response layer coating solution.

[0018] By adopting the above technical solution, deionized water, sodium dihydrogen phosphate, and tannic acid are mixed and stirred to form a homogeneous system. Simultaneously, the pH of the system is adjusted to ensure that the tannic acid exists in a stable state in the solution, resulting in a coating solution with a well-defined interfacial shear response layer. When this coating solution is subsequently applied to the wound contact side of the main hydrogel layer gel blank, it can form an interfacial layer structure containing tannic acid and buffer salt system on the surface of the main hydrogel layer. This interfacial layer participates in the formation of the wound interface structure during use, thereby improving the interfacial stability of the main hydrogel layer under the action of gravity and wound exudate, and reducing the possibility of migration or displacement of the main hydrogel layer.

[0019] Preferably, in step S5, the gel structure includes the following steps: The interfacial shear response layer coating solution is poured onto the wound contact side of the main hydrogel layer gel blank, spread evenly, and the wet coating amount is controlled at 0.05–0.60 g / cm². It is then allowed to stand and integrate at 10–35℃ for 5–120 min to obtain the gel structure.

[0020] By adopting the above technical solution, the interfacial shear response layer coating liquid is inverted and applied to the wound contact side of the main hydrogel layer gel blank and scraped, so that the interfacial shear response layer coating liquid forms a continuous covering layer on the surface of the main hydrogel layer. By allowing it to stand and integrate, the covering layer and the main hydrogel layer gel blank are combined to obtain an integrated gel structure. This makes the interfacial shear response layer stably set on the wound contact side of the main hydrogel layer. During use, it forms an interfacial layer structure with shear response characteristics, which helps the main hydrogel layer maintain the stability of the interfacial structure under the action of gravity and wound exudate, and reduces the possibility of migration or displacement of the overall gel structure.

[0021] Preferably, in step S6, during the compounding process, the temperature is 20–60°C, the pressure is 0.02–0.30 MPa, the compounding time is 5–180 s, and then the mixture is placed at 20–25°C for 5–30 min.

[0022] By adopting the above technical solution, the backing layer is composited with the integrated gel structure under controlled temperature and pressure conditions, and then placed after composite formation. This allows a stable composite state to be formed between the backing layer and the gel structure, thereby maintaining the predetermined layered distribution relationship of the main hydrogel layer and its surface interfacial shear response layer in the overall structure. This avoids interlayer relative displacement during subsequent processing or use, which helps maintain the overall stability of the gel structure in the application state and provides conditions for the wound dressing to maintain its structural integrity and functional consistency during use.

[0023] Preferably, in step S6, the post-processing includes cutting, packaging, and sterilization. The packaging is carried out in an environment with a temperature of 20–25°C and a relative humidity of 20–60%. The sterilization method is electron beam sterilization, and the electron beam dose is 5–20 kGy.

[0024] By adopting the above technical solution, the composite wound dressing is cut, packaged, and sterilized to obtain a finished product with clear dimensions and complete structure. Packaging under controlled temperature and relative humidity helps maintain the stability of the gel structure and each layer during the packaging process. Electron beam sterilization ensures that the wound dressing meets the hygiene requirements before use without changing the existing structure of the main hydrogel layer, the interfacial shear response layer, and the backing layer. This guarantees that the resulting bio-based hydrogel wound dressing can maintain its structural integrity and intended function during application.

[0025] This invention provides a bio-based hydrogel wound dressing and its preparation method. It has the following beneficial effects: 1. This invention provides an interfacial shear response layer containing tannic acid and a buffer salt system on the surface of the main hydrogel layer. This allows the wound dressing to form a gel structure with high shear resistance at the interface after contacting wound exudate. This effectively improves the interfacial stability between the gel and the wound under the influence of gravity and the wetting of wound exudate, and significantly reduces the migration and displacement of the hydrogel during use.

[0026] 2. This invention utilizes a dynamic cross-linked network constructed from pullulan oxide and soy protein isolate in the main hydrogel layer, and modifies the polysaccharide by immobilizing it with citric acid and hydroxylamine acetate. This allows the gel to degrade primarily through network rearrangement and gradual fragmentation, avoiding the instantaneous release of large amounts of low-molecular-weight fragments. This effectively reduces the adverse effects of irritating small molecules on wound tissue caused by excessively rapid local degradation, thereby improving biocompatibility and comfort during wound dressing.

[0027] 3. This invention integrates the main hydrogel layer and the interfacial shear response layer into a single design, so that the gel maintains good softness and liquid absorption capacity while having shear response characteristics at the wound interface. This avoids relying solely on increasing the overall crosslinking density or adding external adhesives to achieve fixation, thus taking into account fit, stability and comfort, and improving the problems of slippage and poor fit of traditional hydrogel wound dressings.

[0028] 4. This invention uses polysaccharides and plant proteins as the main raw materials. The preparation process is mild and the composition is well-defined. All the layer structures used can be achieved by conventional solution mixing, casting and coating methods. It has good process controllability and repeatability, and is suitable for large-scale preparation. At the same time, while ensuring anti-displacement performance and biosafety, it has good moisture permeability and wound adaptability. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Example 1 This invention provides a bio-based hydrogel wound dressing, comprising a main hydrogel layer, an interfacial shear response layer, and a backing layer. The precursor mixture of the main hydrogel layer comprises the following raw materials in parts by weight: 350 parts of OP-N stock solution and 350 parts of SPI stock solution. The OP-N mother liquor was prepared from 300 parts of OP mother liquor, 0.5 parts of citric acid, 0.5 parts of hydroxylamine acetate, and 0.2 parts of 1 mol / L NaOH. The OP mother liquor consists of 900 parts deionized water, 20 parts pullulan, sodium periodate (mass ratio of pullulan to sodium periodate is 0.02:1), and ethylene glycol (mass ratio of sodium periodate to ethylene glycol is 0.3:1.0). The SPI mother liquor consists of 850 parts deionized water, 20 parts soy protein isolate, and 0.2 parts 1 mol / L NaOH. The interfacial shear response layer coating solution comprises the following raw materials in parts by weight: 145 parts deionized water, 0.3 parts sodium dihydrogen phosphate, 0.1 parts tannic acid, and 0.05 parts 1 mol / L NaOH; The backing layer is a PLA moisture-permeable membrane.

[0032] The above-mentioned method for preparing the bandage includes the following steps: S1, preparing OP stock solution; The steps for preparing the OP mother liquor are as follows: Add 900 parts of deionized water to the reaction vessel, add 20 parts of pullulan, and stir at 4℃ and 200 rpm for 0.5 h until completely dissolved to obtain polysaccharide mother liquor; The temperature of the polysaccharide mother liquor was adjusted to 4℃, and then 0.4 parts of sodium periodate were added. The reaction was carried out at 4℃ and 200 rpm in the dark for 0.5 h. Add 0.12 parts of ethylene glycol to sodium periodate at a mass ratio of 0.3:1.0 to the reaction solution, and stir for 10 min at 4℃ and 200 rpm to terminate the reaction. The reaction solution was dialyzed at 4°C for 12 hours, with water changed 4 times, to obtain the OP solution. The OP solution was concentrated under reduced pressure to a solid content of 4 wt% to obtain the OP mother liquor; S2. Citric acid and hydroxylamine acetate (AOA) were added to the OP mother liquor for immobilization reaction. After purification and immobilization adjustment, the OP-N mother liquor was prepared. The immobilized reaction, after purification and immobilized formulation, includes the following steps: Add 0.5 parts citric acid and 0.5 parts hydroxylamine acetate to 300 parts OP mother liquor, stir for 10 min at 20℃ and 200 rpm, and then add 0.2 parts 1 mol / L NaOH to adjust the pH to 6.0; The mixture was reacted at 35°C and 100 rpm for 0.5 h. The reaction solution was dialyzed at 4°C for 6 hours, with water changed 3 times, to obtain an OP-N solution; The OP-N solution was adjusted to a solid content of 6 wt% to obtain the OP-N mother liquor; S3. Dissolve soy protein isolate in deionized water and adjust the pH to prepare SPI mother liquor; The preparation of SPI mother liquor includes the following steps: Mix 850 parts of deionized water and 20 parts of soy protein isolate, stir at 20℃ and 300 rpm for 0.5 h until completely dissolved, add 0.2 parts of 1 mol / L NaOH to adjust the pH to 6.6, and obtain the SPI mother liquor; S4. Prepare the precursor mixture of the main hydrogel layer by mixing OP-N mother liquor, SPI mother liquor and deionized water in sequence. After pH adjustment, degassing and casting, the main hydrogel layer gel blank is obtained. The process of obtaining the main hydrogel layer gel preform includes the following steps: First, add 350 parts of SPI mother liquor to the mixing container. Then, slowly add 350 parts of OP-N mother liquor over a 5-minute period while stirring at 200 rpm. Continue stirring at 200 rpm for 3 minutes. Add 1 mol / L NaOH to adjust the pH of the mixture to 6.6; The mixture was degassed at 15℃ and −0.06MPa for 2 min; The degassed mixture was poured into a mold, the wet film thickness was controlled to be 1.5 mm, and it was allowed to stand at 10℃ for 3 minutes to form a gel, thus obtaining the main hydrogel layer gel preform. S5. Prepare an interfacial shear response layer coating solution containing tannic acid, apply it to the wound contact side of the main hydrogel layer gel blank and let it stand to integrate to form a gel structure. The steps for preparing the interfacial shear-responsive layer coating solution containing tannic acid are as follows: Mix 145 parts of deionized water, 0.3 parts of sodium dihydrogen phosphate and 0.1 parts of tannic acid, stir at 20℃ and 200 rpm for 10 min, add 1 mol / L NaOH to adjust the pH to 6.8, and obtain the interfacial shear response layer coating solution. The gel structure includes the following steps: The interface shear response layer coating liquid was poured onto the wound contact side of the main hydrogel layer gel blank, spread evenly and the wet coating amount was controlled to be 0.05 g / cm², and allowed to stand and integrate for 5 min at 10℃ to obtain the gel structure. S6. The PLA breathable membrane is laminated onto the non-wound side of the integrated gel structure, and after post-processing, the finished product is obtained. During the compounding process, the temperature was 20℃, the pressure was 0.02MPa, and the compounding time was 5s, followed by placement at 20℃ for 5min. The post-processing includes cutting, packaging and sterilization. The packaging is carried out at a temperature of 20°C and a relative humidity of 20%. The sterilization method is electron beam sterilization with an electron beam dose of 5 kGy.

[0033] Example 2 This invention provides a bio-based hydrogel wound dressing, comprising a main hydrogel layer, an interfacial shear response layer, and a backing layer. The precursor mixture of the main hydrogel layer comprises the following raw materials in parts by weight: 450 parts of OP-N stock solution and 500 parts of SPI stock solution. The OP-N mother liquor was prepared from 500 parts of OP mother liquor, 4.25 parts of citric acid, 3.25 parts of hydroxylamine acetate, and 4.1 parts of 1 mol / L NaOH. The OP mother liquor consists of 940 parts deionized water, 60 parts pullulan, sodium periodate (mass ratio of pullulan to sodium periodate is 0.10:1), and ethylene glycol (mass ratio of sodium periodate to ethylene glycol is 0.75:1.0). The SPI mother liquor consisted of 915 parts deionized water, 85 parts soy protein isolate, and 3.1 parts 1 mol / L NaOH. The interfacial shear response layer coating solution comprises the following raw materials in parts by weight: 220 parts deionized water, 1.15 parts sodium dihydrogen phosphate, 0.8 parts tannic acid, and 1.025 parts 1 mol / L NaOH; The backing layer is a PLA moisture-permeable membrane.

[0034] The above-mentioned method for preparing the bandage includes the following steps: S1, preparing OP stock solution; The steps for preparing the OP mother liquor are as follows: Add 940 parts of deionized water to the reaction vessel, add 60 parts of pullulan, and stir at 14.5℃ and 500rpm for 2.25h until completely dissolved to obtain polysaccharide mother liquor; The temperature of the polysaccharide mother liquor was adjusted to 12℃, and then 6 parts of sodium periodate were added. The reaction was carried out at 12℃ and 400 rpm in the dark for 3.25 h. Add 4.5 parts of ethylene glycol to the reaction solution and stir for 35 min at 12°C and 400 rpm to terminate the reaction; The reaction solution was dialyzed at 14.5℃ for 30 hours with 8 water changes to obtain the OP solution. The OP solution was concentrated under reduced pressure to a solid content of 7 wt% to obtain the OP mother liquor; S2. Citric acid and hydroxylamine acetate (AOA) were added to the OP mother liquor for immobilization reaction. After purification and immobilization adjustment, the OP-N mother liquor was prepared. The immobilized reaction, after purification and immobilized formulation, includes the following steps: Add 4.25 parts citric acid and 3.25 parts hydroxylamine acetate to 500 parts OP mother liquor, stir for 35 min at 27.5℃ and 400 rpm, and then add 4.1 parts 1 mol / L NaOH to adjust the pH to 6.6; The mixture was reacted at 50°C and 200 rpm for 4.25 h. The reaction solution was dialyzed at 14.5℃ for 15 hours, with water changes 5.5 times, to obtain an OP-N solution; The OP-N solution was adjusted to a solid content of 9 wt% to obtain the OP-N mother liquor; S3. Dissolve soy protein isolate in deionized water and adjust the pH to prepare SPI mother liquor; The preparation of SPI mother liquor includes the following steps: Mix 915 parts of deionized water and 85 parts of soy protein isolate, stir at 35℃ and 650 rpm for 1.75 h until completely dissolved, add 3.1 parts of 1 mol / L NaOH to adjust the pH to 7.0, and obtain SPI mother liquor; S4. Prepare the precursor mixture of the main hydrogel layer by mixing OP-N mother liquor, SPI mother liquor and deionized water in sequence. After pH adjustment, degassing and casting, the main hydrogel layer gel blank is obtained. The process of obtaining the main hydrogel layer gel preform includes the following steps: First, add 500 parts of SPI mother liquor to the mixing container. Then, slowly add 450 parts of OP-N mother liquor over a period of 12.5 minutes while stirring at 350 rpm. Continue stirring at 350 rpm for 11.5 minutes. Add 1 mol / L NaOH to adjust the pH of the mixture to 7.0; The mixture was degassed for 11 min at 22.5℃ and −0.0775 MPa. The degassed mixture was poured into a mold, the wet film thickness was controlled to be 3.25 mm, and it was allowed to stand at 20℃ for 31.5 min to form a gel, thus obtaining the main hydrogel layer gel preform. S5. Prepare an interfacial shear response layer coating solution containing tannic acid, apply it to the wound contact side of the main hydrogel layer gel blank and let it stand to integrate to form a gel structure. The steps for preparing the interfacial shear-responsive layer coating solution containing tannic acid are as follows: Mix 220 parts of deionized water, 1.15 parts of sodium dihydrogen phosphate and 0.8 parts of tannic acid, stir at 25℃ and 400 rpm for 35 min, add 1 mol / L NaOH to adjust the pH to 7.1, and obtain the interfacial shear response layer coating solution. The gel structure includes the following steps: The interface shear response layer coating liquid was poured onto the wound contact side of the main hydrogel layer gel blank, spread evenly and the wet coating amount was controlled at 0.325 g / cm², and allowed to stand and integrate at 22.5℃ for 62.5 min to obtain the gel structure. S6. The PLA breathable membrane is laminated onto the non-wound side of the integrated gel structure, and after post-processing, the finished product is obtained. During the compounding process, the temperature was 40℃, the pressure was 0.16MPa, the compounding time was 92.5s, and then the mixture was placed at 22.5℃ for 17.5min. The post-processing includes cutting, packaging and sterilization. The packaging is carried out at a temperature of 22.5℃ and a relative humidity of 40%. The sterilization method is electron beam sterilization with an electron beam dose of 12.5kGy.

[0035] Example 3 This invention provides a bio-based hydrogel wound dressing, comprising a main hydrogel layer, an interfacial shear response layer, and a backing layer. The precursor mixture of the main hydrogel layer comprises the following raw materials in parts by weight: 550 parts of OP-N stock solution and 650 parts of SPI stock solution. The OP-N mother liquor was prepared from 700 parts of OP mother liquor, 8.0 parts of citric acid, 6.0 parts of hydroxylamine acetate, and 8.0 parts of 1 mol / L NaOH. The OP mother liquor consists of 980 parts deionized water, 100 parts pullulan, sodium periodate (in a mass ratio of 0.18:1 to pullulan), and ethylene glycol (in a mass ratio of 1.2:1.0 to sodium periodate). The SPI mother liquor consists of 980 parts deionized water, 150 parts soy protein isolate, and 6.0 parts 1 mol / L NaOH; The interfacial shear response layer coating solution comprises the following raw materials in parts by weight: 295 parts deionized water, 2.0 parts sodium dihydrogen phosphate, 1.5 parts tannic acid, and 2.0 parts 1 mol / L NaOH; The backing layer is a PLA moisture-permeable membrane.

[0036] The preparation method of the above-mentioned bandage includes the following steps: S1. Prepare OP mother liquor; The steps for preparing the OP mother liquor are as follows: Add 980 parts of deionized water to the reaction vessel, add 100 parts of pullulan, and stir at 25°C and 800 rpm for 4 hours until completely dissolved to obtain polysaccharide mother liquor. The temperature of the polysaccharide mother liquor was adjusted to 20℃, and then 18 parts of sodium periodate were added. The reaction was carried out at 20℃ and 600 rpm in the dark for 6 hours. Add 21.6 parts of ethylene glycol to the reaction solution and stir for 60 min at 20°C and 600 rpm to terminate the reaction; The reaction solution was dialyzed at 25°C for 48 hours with 12 water changes to obtain the OP solution. The OP solution was concentrated under reduced pressure to a solid content of 10 wt% to obtain the OP mother liquor; S2. Citric acid and hydroxylamine acetate (AOA) were added to the OP mother liquor for immobilization reaction. After purification and immobilization adjustment, the OP-N mother liquor was prepared. The immobilized reaction, after purification and immobilized formulation, includes the following steps: Add 8.0 parts of citric acid and 6.0 parts of hydroxylamine acetate to 700 parts of OP mother liquor, stir for 60 min at 35℃ and 600 rpm, and then add 8.0 parts of 1 mol / L NaOH to adjust the pH to 7.2; The mixture was reacted at 65℃ and 300rpm for 8 hours. The reaction solution was dialyzed at 25°C for 24 hours, with water changed 8 times, to obtain an OP-N solution; The OP-N solution was adjusted to a solid content of 12 wt% to obtain the OP-N mother liquor; S3. Dissolve soy protein isolate in deionized water and adjust the pH to prepare SPI mother liquor; The preparation of SPI mother liquor includes the following steps: Mix 980 parts of deionized water and 150 parts of soy protein isolate, and stir at 50℃ and 1000rpm for 3 hours until completely dissolved. Add 6.0 parts of 1mol / L NaOH to adjust the pH to 7.4 to obtain the SPI mother liquor. S4. Prepare the precursor mixture of the main hydrogel layer by mixing OP-N mother liquor, SPI mother liquor and deionized water in sequence. After pH adjustment, degassing and casting, the main hydrogel layer gel blank is obtained. The process of obtaining the main hydrogel layer gel preform includes the following steps: First, add 650 parts of SPI mother liquor to the mixing container. Then, slowly add 550 parts of OP-N mother liquor over a period of 20 minutes while stirring at 500 rpm. Continue stirring at 500 rpm for another 20 minutes. Add 1 mol / L NaOH to adjust the pH of the mixture to 7.4; The mixture was degassed at 30℃ and −0.095MPa for 20 min; The degassed mixture was poured into a mold, the wet film thickness was controlled to be 5.0 mm, and it was allowed to stand at 30℃ for 60 min to form a gel, thus obtaining the main hydrogel layer gel preform. S5. Prepare an interfacial shear response layer coating solution containing tannic acid, apply it to the wound contact side of the main hydrogel layer gel blank and let it stand to integrate to form a gel structure. The steps for preparing the interfacial shear-responsive layer coating solution containing tannic acid are as follows: Mix 295 parts of deionized water, 2.0 parts of sodium dihydrogen phosphate and 1.5 parts of tannic acid, stir at 30℃ and 600 rpm for 60 min, add 1 mol / L NaOH to adjust the pH to 7.4, and obtain the interfacial shear response layer coating solution. The gel structure includes the following steps: The interface shear response layer coating liquid was poured onto the wound contact side of the main hydrogel layer gel blank, spread evenly and the wet coating amount was controlled at 0.60 g / cm², and allowed to stand and integrate at 35℃ for 120 min to obtain the gel structure. S6. The PLA breathable membrane is laminated onto the non-wound side of the integrated gel structure, and after post-processing, the finished product is obtained. During the compounding process, the temperature was 60℃, the pressure was 0.30MPa, and the compounding time was 180s, followed by placement at 25℃ for 30min. The post-processing includes cutting, packaging and sterilization. The packaging is carried out at a temperature of 25°C and a relative humidity of 60%. The sterilization method is electron beam sterilization with an electron beam dose of 20 kGy.

[0037] Comparative Example 1 The only difference from Example 2 is that hydroxylamine acetate was not added when preparing the OP-N mother liquor.

[0038] Comparative Example 2 The only difference from Example 2 is that potassium permanganate is used instead of sodium periodate when preparing the OP mother liquor.

[0039] Comparative Example 3 The only difference from Example 2 is that tannic acid was not added when preparing the interfacial shear response layer coating solution.

[0040] Comparative Example 4 The only difference from Example 2 is that in step S4, OP-N mother liquor is added first, followed by SPI mother liquor.

[0041] Comparative Example 5 The only difference from Example 2 is that the dialysis purification step of the OP mother liquor is omitted in step S1.

[0042] Comparative Example 6 The only difference from Example 2 is that in step S6, gamma ray irradiation sterilization is used instead of electron beam sterilization.

[0043] Test samples: Bio-based hydrogel wound dressings prepared in Examples 1, 2, and 3; Control sample: Hydrogel wound dressings prepared in Comparative Examples 1-6; Sample preparation: All samples were cut into 2cm×2cm square specimens, retaining the actual thickness during the preparation process, and were then sterilized before use.

[0044] Experiment 1: Gel migration and displacement test under simulated wound environment The procedure was slightly modified based on Appendix A of GB / T 39230-2020 "Medical Hydrogel Dressings". The specific steps are as follows: A sterile porcine dermal layer with a 2 mm thick layer at the bottom was used to simulate the wound matrix. The temperature was controlled at 37°C. PBS buffer solution was prepared with NaCl 8.0 g / L, KCl 0.2 g / L, Na2HPO4 1.44 g / L, KH2PO4 0.24 g / L, pH=7.4, and sterilized for later use. The simulated wound matrix was fixed on a 30° inclined experimental table. Samples from Examples 1-3 and Comparative Examples 1-6 were taken, and the interface shear response layer was flattened and gently pressed for 30 seconds with the matrix facing upwards. 2 mL of simulated exudate was added to the sample surface at a rate of 0.5 mL / min. The sample was observed continuously at 37°C and 30° inclination for 6 hours. The displacement distance of the sample edge relative to the initial position was measured with calipers every hour. Three parallel experiments were set up for each sample, and the average value was taken as the final data. The evaluation index was the cumulative migration displacement distance over 6 hours.

[0045] Experiment 2: In vitro degradation of gel and cytotoxicity test of degradation products Referring to GB / T 16886.5-2017 "Biological Evaluation of Medical Devices - Part 5: In Vitro Cytotoxicity Tests", for the preparation of degradation solution, the PLA backing layer of each sample was removed, and 1cm×1cm×corresponding thickness of the main hydrogel layer and interfacial shear response layer samples were cut. The initial mass m0 was accurately weighed, and PBS buffer was added at a liquid-solid ratio of 20mL:1g. The samples were placed in a constant temperature shaker at 37℃ and 100rpm to accelerate degradation. The supernatant was collected at 24h, 48h, and 72h and filtered through a 0.22μm filter membrane to obtain the degradation solution. At the same time, the samples were taken out, freeze-dried, and weighed m1. The degradation rate was calculated as (m0-m1) / m0×100%. The cytotoxicity assay was performed using the MTT assay. L929 fibroblasts were seeded at 5 × 10³ cells / well in 96-well plates and cultured in 100 μL of DMEM complete medium at 37°C with 5% CO2 for 24 h to allow cell adhesion. The degradation solution at each time point was mixed with DMEM at a 1:1 ratio to prepare a culture medium containing the degradation solution. After removing the original medium, 100 μL of the corresponding medium was added to each well and cultured for 24 h. Then, 20 μL of 5 mg / mL MTT solution was added to each well and cultured for 4 h. After removing the supernatant, 150 μL of DMSO was added and shaken for 10 min to dissolve the crystals. The absorbance (OD) value was measured at 490 nm using a microplate reader. The evaluation indicators were degradation rate and relative cell viability = (OD value of sample group / OD value of blank control group) × 100% (≥80% indicates no obvious toxicity).

[0046] Experiment 3: Verification of gel stability and wound compatibility in animal wound models Referring to YY / T 0148-2006 "Rabbit or Rat Skin Trauma Model for Performance Evaluation of Medical Dressings", 48 SPF-grade SD rats were randomly divided into 8 groups corresponding to Examples 1-3 and Comparative Examples 1-6. After anesthesia with intraperitoneal injection of 30 mg / kg sodium pentobarbital, the rats' backs were shaved. Full-thickness skin defects extending to the fascia layer were prepared using a 1.5 cm diameter sterile biopsy punch. Each sample was cut into 1.8 cm diameter circles to cover the corresponding group's wound and gently fixed with sterile gauze. The gel migration / fall-off was observed and recorded on 1, 3, 5, and 7 days postoperatively. A scoring method was used for evaluation: 0 points = complete adhesion, 1 point = slight edge lifting ≤1 mm, 2 points = obvious edge lifting >1 mm and ≤3 mm, 3 points = partial fall-off ≤1 / 3, and 4 points = most of the fall-off >1 / 3. Wound images were taken at 3, 7, and 14 days post-surgery. The area was measured using ImageJ software, and the healing rate was calculated as (initial wound area - remaining wound area) / initial wound area × 100%. On 7 days post-surgery, three rats from each group were randomly selected, and the central tissue of the wound was routinely paraffin-embedded, sectioned, and stained with hematoxylin and eosin (HE). The inflammatory response and granulation tissue growth were observed under an optical microscope. The evaluation indicators were gel stability score, wound healing rate, and inflammatory response grade, where grade 0 = no inflammatory cells, grade 1 = few cells, grade 2 = moderate amount, and grade 3 = large amount.

[0047] Table 1: Test data on gel migration and displacement under simulated wound conditions Table 2: Data on in vitro degradation of gel and cytotoxicity of degradation products Table 3: Experimental data on gel stability and wound compatibility in animal wound models By comparing the experimental data of the examples and the comparative examples, it can be seen that: As can be seen from Example 2 and Comparative Examples 1 and 3, and Table 1, the excellent anti-migration properties of the gel depend on the synergistic effect of hydroxylamine acetate immobilization and the tannic acid interfacial shear response layer. The cumulative migration displacement distances of Comparative Examples 1 and 3 over 6 hours reached 1.85 mm and 2.01 mm, respectively, significantly higher than the 0.18 mm of Example 2. This indicates that the immobilization effect of hydroxylamine acetate can improve the stability of the gel structure, and the tannic acid interfacial layer can enhance the adhesion to the wound surface. The two form a double protection to reduce displacement under gravity and exudate. The absence or incompleteness of a single component cannot replace this synergistic anti-migration effect.

[0048] Combining Example 2 and Comparative Examples 1 and 3 with Table 2, it can be seen that the key to regulating the gel degradation rate and reducing the irritation of degradation products lies in the complete synergistic system of hydroxylamine acetate and tannic acid. The degradation rates of Comparative Examples 1 and 3 after 72 hours were 42.1% and 48.9%, respectively, with relative cell viability of only 56.8% and 52.3%, while the degradation rate of Example 2 after 72 hours was only 7.9%, with a cell viability of 94.5%. This indicates that hydroxylamine acetate can strengthen the gel cross-linking network and slow down degradation, while tannic acid further inhibits localized excessively rapid degradation. The two work synergistically to reduce the generation of low-molecular-weight irritating products. The absence of either key component will lead to uncontrolled degradation and a significant increase in irritation.

[0049] Combining Example 2 and Comparative Examples 1 and 3 with Table 3, it can be seen that the excellent in vivo performance of the wound dressing is a comprehensive manifestation of its anti-migration ability and low-irritation degradation characteristics. Comparative Example 1 not only showed large migration displacement, but also had a gel stability score of 3.2 points at 7 days post-operation, a wound healing rate of only 42.1%, and an inflammation grade of 2.5. Comparative Example 3 had a stability score of 3.5 points, a healing rate of 38.9%, and an inflammation grade of 2.8, all of which were far worse than the 0.3 points, 72.5%, and 0.6 grades of Example 2. This indicates that the anti-migration ability ensures the gel continuously covers the wound, while the low-irritation degradation provides a friendly environment for wound healing, and the two work synergistically to achieve a leap in in vivo performance.

[0050] Combining Example 2 and Comparative Examples 2, 4, and 5 with Tables 1-3, it can be seen that the effectiveness of the core innovative system relies on the auxiliary guarantee of specific process parameters. The 6-hour migration displacements of Comparative Examples 2, 4, and 5 were 1.23 mm, 1.56 mm, and 1.34 mm, respectively; the 72-hour degradation rates were 35.7%, 39.5%, and 37.8%; and the 7-day healing rates were 48.6%, 45.3%, and 46.7%, respectively, all inferior to Example 2. This indicates that the selective oxidation of sodium periodate, the mixing order of adding SPI mother liquor before OP-N mother liquor, and the dialysis purification steps can optimize the gel cross-linking structure and purity, providing a foundation for the synergistic effect of the hydroxylamine acetate and tannic acid system. The absence or replacement of process parameters will lead to a decline in overall performance.

[0051] Combining Example 2 and Comparative Example 6 with Tables 1-3, it can be seen that Comparative Example 6, by using γ-ray sterilization instead of electron beam sterilization, showed better performance than other comparative examples but worse performance than Example 2 in all aspects, including a migration displacement of 0.45 mm at 6 hours, a degradation rate of 14.2% at 72 hours, and a stability score of 1.1 points at 7 days post-operation. Meanwhile, Example 2, with its advantage of slight damage to the gel structure caused by electron beam sterilization, combined with the core synergistic system, achieved the best overall effect of anti-migration, low irritation, and high biocompatibility.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bio-based hydrogel wound dressing comprising a bulk hydrogel layer, an interfacial shear response layer, and a backing layer, characterized in that, The precursor mixture of the main hydrogel layer comprises the following raw materials in parts by weight: 350–550 parts of OP-N mother liquor and 350–650 parts of SPI mother liquor. The OP-N mother liquor is composed of 300–700 parts of OP mother liquor, 0.5–8.0 parts of citric acid, 0.5–6.0 parts of hydroxylamine acetate, and 0.2–8.0 parts of 1mol / L NaOH. The OP mother liquor comprises 900–980 parts deionized water, 20–100 parts pullulan, sodium periodate in a mass ratio of 0.02–0.18:1 to pullulan, and ethylene glycol in a mass ratio of 0.3–1.2:1.0 to sodium periodate. The SPI mother liquor comprises 850–980 parts deionized water, 20–150 parts soy protein isolate, and 0.2–6.0 parts 1 mol / L NaOH. The interfacial shear response layer coating solution comprises the following raw materials in parts by weight: 145–295 parts deionized water, 0.3–2.0 parts sodium dihydrogen phosphate, 0.1–1.5 parts tannic acid, and 0.05–2.0 parts 1 mol / L NaOH or 0.05–2.0 parts 1 mol / L HCl. The backing layer is a PLA moisture-permeable membrane.

2. A method for preparing a bio-based hydrogel wound dressing, characterized in that, The bio-based hydrogel wound dressing according to claim 1 comprises the following steps: S1. Prepare OP mother liquor; S2. Citric acid and hydroxylamine acetate (AOA) were added to the OP mother liquor for immobilization reaction. After purification and immobilization adjustment, OP-N mother liquor was prepared. S3. Dissolve soy protein isolate in deionized water and adjust the pH to prepare SPI mother liquor; S4. Prepare the precursor mixture of the main hydrogel layer by mixing OP-N mother liquor, SPI mother liquor and deionized water in sequence. After pH adjustment, degassing and casting, the main hydrogel layer gel blank is obtained. S5. Prepare an interfacial shear response layer coating solution containing tannic acid, apply it to the wound contact side of the main hydrogel layer gel blank and let it stand to integrate to form a gel structure. S6. The PLA breathable membrane is laminated onto the non-wound side of the integrated gel structure, and after post-processing, the finished product is obtained.

3. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S1, the steps for preparing the OP mother liquor are as follows: Add deionized water to the reaction vessel, add pullulan, and stir at 4–25℃ and 200–800 rpm for 0.5–4 h until completely dissolved to obtain polysaccharide mother liquor; Adjust the temperature of the polysaccharide mother liquor to 4–20℃, then add sodium periodate, and react in the dark at 4–20℃ and 200–600 rpm for 0.5–6 hours. Add ethylene glycol to the reaction solution and stir for 10–60 min at 4–20°C and 200–600 rpm to terminate the reaction. The reaction solution was dialyzed at 4–25℃ for 12–48 h, with water changes 4–12 times, to obtain the OP solution; The OP solution was concentrated under reduced pressure to a solid content of 4–10 wt% to obtain the OP mother liquor.

4. The process for the preparation of a bio-based hydrogel wound dressing as claimed in claim 2, wherein, In step S2, the immobilized reaction, after purification and immobilized formulation, includes the following steps: Add citric acid and hydroxylamine acetate to the OP mother liquor, stir for 10–60 min at 20–35℃ and 200–600 rpm, and then add 0.2–8.0 parts by weight of 1 mol / L NaOH to adjust the pH to 6.0–7.

2. The mixture was reacted at 35–65℃ and 100–300 rpm for 0.5–8 h. The reaction solution was dialyzed at 4–25℃ for 6–24 h with water changes 3–8 times to obtain OP-N solution; The OP-N solution was adjusted to a solid content of 6–12 wt% to obtain the OP-N mother liquor.

5. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S3, the preparation of the SPI mother liquor includes the following steps: Deionized water and soy protein isolate were mixed and stirred at 20–50°C and 300–1000 rpm for 0.5–3 h until completely dissolved. 0.2–6.0 parts by weight of 1 mol / L NaOH were added to adjust the pH to 6.6–7.4 to obtain the SPI mother liquor.

6. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S4, obtaining the main hydrogel layer gel preform includes the following steps: First, add SPI mother liquor to the mixing container. Under stirring conditions of 200–500 rpm, slowly add OP-N mother liquor over a period of 5–20 min. Continue stirring at 200–500 rpm for 3–20 min. Add 1 mol / L NaOH to adjust the pH of the mixture to 6.6–7.4; The mixture was degassed at 15–30 °C and −0.06 to −0.095 MPa for 2–20 min. The degassed mixture is poured into a mold, and the wet film thickness is controlled at 1.5–5.0 mm. The mixture is allowed to stand at 10–30℃ for 3–60 min to form a gel, thus obtaining the main hydrogel layer gel preform.

7. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S5, the preparation of the interfacial shear response layer coating solution containing tannic acid is as follows: Deionized water, sodium dihydrogen phosphate, and tannic acid were mixed and stirred at 20–30°C and 200–600 rpm for 10–60 min. 1 mol / L NaOH was added to adjust the pH to 6.8–7.4 to obtain the interfacial shear response layer coating solution.

8. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S5, the gel structure includes the following steps: The interfacial shear response layer coating solution is poured onto the wound contact side of the main hydrogel layer gel blank, spread evenly, and the wet coating amount is controlled at 0.05–0.60 g / cm². It is then allowed to stand and integrate at 10–35℃ for 5–120 min to obtain the gel structure.

9. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S6, during the compounding process, the temperature is 20–60℃, the pressure is 0.02–0.30MPa, and the compounding time is 5–180s, followed by placement at 20–25℃ for 5–30min.

10. The method for preparing a bio-based hydrogel wound dressing according to claim 2, characterized in that, In step S6, the post-processing includes cutting, packaging and sterilization. The packaging is carried out in an environment with a temperature of 20–25°C and a relative humidity of 20–60%. The sterilization method is electron beam sterilization with an electron beam dose of 5–20 kGy.

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