Dressing for skin wound repair and preparation method thereof

Abstract

The invention provides a dressing for repairing a skin wound and a preparation method of the dressing, and aims to overcome the limitation that the traditional dressing is insufficient in antibacterial property, low in mechanical strength and poor in biocompatibility. According to the dressing, polyvinyl alcohol and chitosan are used as matrix materials, and the antibacterial ability and the healing promoting effect are remarkably improved by compounding selenium nanoparticles and copper-based nanospheres. The preparation method comprises the following steps: firstly, synthesizing copper-based nanospheres by adopting a microwave-assisted method; secondly, preparing selenium nanoparticles through ultrasonic dispersion; then mixing the two with an emulsifier to form a composite material; and finally, blending the composite material with polyvinyl alcohol and chitosan, adding a cross-linking agent and an ammonium salt solution, and solidifying to form the dressing. The obtained dressing has excellent antibacterial performance, and can effectively inhibit various pathogenic bacteria and promote tissue regeneration.

Description

Technical Field

[0001] The present invention relates to the technical field of antibacterial hydrogel materials, and particularly relates to a dressing for skin wound repair and a preparation method thereof. Background Art

[0002] Skin wound repair is an important research topic in clinical medicine. With the aging of the population and the increase in patients with chronic diseases, the problem of wound healing has attracted increasing attention. The repair process of skin wounds is complex and involves multiple aspects such as tissue regeneration, inflammation control, and infection prevention. Traditional wound dressings such as gauze and cotton pads can provide basic protection, but they are limited in promoting tissue healing and preventing infection.

[0003] In recent years, hydrogels have become a new type of dressing material that has attracted much attention due to their excellent moisture retention, biocompatibility, and adjustability. A hydrogel is a three-dimensional network-structured polymer material that can absorb a large amount of water while maintaining a certain mechanical strength. Its moist environment can promote cell migration and proliferation, thereby accelerating wound healing. In addition, by introducing antibacterial components, hydrogels can also effectively inhibit the growth of pathogenic microorganisms and reduce the risk of infection.

[0004] Although hydrogel dressings have many advantages in theory, the current products on the market still have the following deficiencies: Limited antibacterial performance: Many hydrogel dressings only have a passive protection effect and lack the direct inhibitory ability against bacteria and other pathogens. Once an infection occurs, it will significantly delay the wound healing process. Weak mechanical properties: Some hydrogels have a decreased mechanical strength after absorbing liquid, are prone to rupture or deformation, and are difficult to provide long-term stable protection for the wound. Biocompatibility problems: Some synthetic hydrogels may cause immune reactions or toxic effects, causing secondary harm to patients. Complex preparation process: The preparation processes of some existing high-performance hydrogel dressings are complex and costly, which is not conducive to large-scale production and popularization.

[0005] In view of the above problems, it is particularly important to develop a hydrogel dressing with both antibacterial performance, excellent mechanical strength, and good biocompatibility. Such a dressing should meet the following requirements: Significant antibacterial effect: It can effectively inhibit the growth of common pathogenic bacteria such as Staphylococcus aureus and Escherichia coli, while avoiding the generation of antibiotic resistance. Promote tissue regeneration: By providing a moist environment and necessary nutritional support, it accelerates cell proliferation and the formation of new tissue. Easy to use: It has good flexibility and conformability, and can adapt to wounds in different parts. Economically feasible: The preparation process is simple, the cost is low, and it is suitable for large-scale production. Summary of the Invention

[0006] In view of this, the present invention provides a dressing for skin wound repair and a preparation method thereof, and the technical solution is as follows: A preparation method of a dressing for skin wound repair, comprising the following steps in parts by weight: Dissolve 0.2 parts - 0.8 parts of copper nitrate in 10 times - 20 times of its mass of distilled water, and then dropwise add an aqueous sodium hydroxide solution 15 times - 30 times the mass of copper nitrate, wherein the concentration of the aqueous sodium hydroxide solution is 0.5M, continuously stir for 10min - 20min, and mix and stir to obtain a mixed system. Dropwise add 5 times - 10 times the mass of copper nitrate of ethylenediamine and 10 times - 20 times of isophorone diamine to the mixed system, perform microwave treatment and activation and mixing, then add an ethanol solution with a mass percentage of 60% - 70% 40 times - 60 times the mass of copper nitrate, and vacuum dry at 50°C - 60°C for 10h - 24h to obtain nanospheres; Next, dissolve 0.02 parts - 0.08 parts of selenium nanoparticles in 30 times - 50 times of its mass of acetone, and perform ultrasonic treatment for 1h - 3h to obtain a nano-dispersion; Then, mix the nanospheres, the nano-dispersion and the emulsifier according to a volume ratio of 1:(2 - 5):0.5, stir at 50°C - 60°C for 60min - 80min, separate the product by high-speed centrifugation, wash it successively with acetone and sterilized water, and perform low-temperature drying at -50°C for 20h - 30h to obtain a composite material; Finally, mix the above composite material and polyvinyl alcohol according to a weight ratio of 0.02:(1 - 2), add 15 times - 25 times the mass of polyvinyl alcohol of deionized water, heat to 80°C and stir for 2h - 4h, then add 0.5 times - 1 times the mass of polyvinyl alcohol of chitosan, adjust the pH value to 5, stir at 50°C for 30min, then quickly add a crosslinking agent and an ammonium salt solution, the final mass percentage of the crosslinking agent is 1%, the final mass percentage of the ammonium salt solution is 5%, pour it into a mold, and obtain it after solidification.

[0007] For the preparation method of the dressing for skin wound repair as described above, the emulsifier is at least one of Tween 20, Tween 80, and polyoxyethylene stearate; the crosslinking agent is at least one of glutaraldehyde, sorbitol, and polyethylene glycol.

[0008] For the preparation method of the dressing for skin wound repair as described above, the way to adjust the pH value is by dropping a hydrochloric acid solution; the ammonium salt solution is at least one of ammonium chloride solution, ammonium carbonate solution, and ammonium phosphate solution.

[0009] For the preparation method of the dressing for skin wound repair as described above, the way of mixing and stirring is to stir while performing ultrasonic treatment, wherein the stirring method is mechanical stirring, the rotation speed of the mechanical stirring is 200rpm, the ultrasonic method is water bath ultrasonic, the power of the water bath ultrasonic is 200W - 300W, and the temperature of the water bath ultrasonic is 30°C - 55°C.

[0010] For the preparation method of the dressing for skin wound repair as described, the dropping rate of ethylenediamine is 0.5 mL / min - 1 mL / min, and the dropping rate of isophorone diamine is 0.25 mL / min - 0.5 mL / min.

[0011] For the preparation method of the dressing for skin wound repair as described, the power of the microwave treatment is 500 W - 800 W, and the time of the microwave treatment is 10 min - 20 min.

[0012] For the preparation method of the dressing for skin wound repair as described, the temperature of the activation and mixing is 40°C - 50°C, and the time of the activation and mixing is 2 h - 4 h.

[0013] For the preparation method of the dressing for skin wound repair as described, the rotation speed of the high-speed centrifugation is 6000 rpm, the temperature of the high-speed centrifugation is 4°C, and the time of the high-speed centrifugation is 15 min; the temperature of the solidification is 4°C.

[0014] The dressing for skin wound repair is prepared by using the above-mentioned preparation method.

[0015] The present invention provides a dressing for skin wound repair and its preparation method. Through innovative material combinations and scientific preparation processes, the performance of the dressing has been significantly improved, showing excellent effects in multiple aspects compared with the prior art. The beneficial effects of the present invention are elaborated in detail from the perspectives of antibacterial performance, tissue regeneration ability, mechanical strength, biocompatibility, economic efficiency of the preparation process, multifunctionality, and ease of use. The dressing of the present invention is endowed with excellent antibacterial ability by introducing selenium nanoparticles and nanospheres. Selenium nanoparticles, as a broad-spectrum antibacterial material, can effectively inhibit the growth of various pathogenic bacteria including Staphylococcus aureus and Escherichia coli. This antibacterial effect stems from the redox properties of selenium, which can damage the bacterial cell membrane and interfere with its metabolic process, thus significantly reducing the risk of wound infection. In addition, during the preparation of the nanospheres, components such as copper nitrate, ethylenediamine, and isophorone diamine are used, and through microwave treatment and activation and mixing, a nanostructure with antibacterial activity is formed. The synergistic effect of these nanostructures further enhances the antibacterial effect of the dressing. Different from traditional dressings that only provide a passive physical barrier, the dressing of the present invention can more effectively prevent and control wound infection through an active antibacterial mechanism, shorten the healing time, and provide a safer repair environment for patients. The dressing uses polyvinyl alcohol and chitosan as matrix materials, and both of these materials are recognized as high-molecular materials with excellent biological activity. Polyvinyl alcohol can absorb and retain a large amount of moisture, providing a moist healing environment for the wound. This moist microenvironment helps to promote cell migration and proliferation, and accelerate the formation of new tissue. Chitosan is widely used in the medical field due to its natural biocompatibility and ability to promote tissue repair. The amino and hydroxyl groups in its molecular structure can interact with cells, stimulate tissue regeneration, and have a certain hemostatic effect. In addition, the addition of selenium nanoparticles further enhances the biological activity of the dressing. Research shows that selenium can promote cell growth and has antioxidant effects, effectively reducing the inflammatory response. Through the synergistic effect of these components, the dressing of the present invention can form a microenvironment conducive to healing at the wound site, significantly accelerating the wound repair process and shortening the recovery period of patients. The present invention prepares a hydrogel dressing with a three-dimensional network structure by mixing polyvinyl alcohol and chitosan and combining cross-linking treatments with cross-linking agents (such as glutaraldehyde, sorbitol, or polyethylene glycol) and ammonium salt solutions. This structure can not only effectively absorb wound exudate, maintain the wound moist, but also provide sufficient mechanical strength to prevent the dressing from deforming or rupturing after absorbing liquid. The introduction of nanospheres and selenium nanoparticles further enhances the mechanical properties of the hydrogel, making it excellent in tensile strength and tear resistance. This stable mechanical property ensures that the dressing can provide long-term physical protection for the wound during application, avoiding secondary damage to the wound caused by external factors. In addition, the flexibility and elasticity of the dressing enable it to adapt to wounds of different shapes and locations, enhancing its practicality.The main components of the dressing, polyvinyl alcohol and chitosan, are both approved biomaterials with good biocompatibility and low toxicity, and are not likely to trigger immune reactions or allergic reactions. During the preparation process, steps such as low-temperature drying and washing with sterile water are adopted to ensure the purity and safety of the dressing, minimizing potential contamination and harmful residues. In addition, the dressing of the present invention does not rely on traditional antibiotic components, avoiding the risks of antibiotic resistance and drug side effects, and is particularly suitable for patients who are allergic or intolerant to traditional antibacterial agents. This high biocompatibility makes the dressing safer and more reliable in clinical applications, effectively reducing the risk of secondary injury to patients. The preparation method of the present invention is reasonably designed, the process flow is clear, and the raw materials used, such as copper nitrate, selenium nanoparticles, polyvinyl alcohol, and chitosan, are all easily obtainable and of low cost. No complex equipment and expensive reagents are required during the preparation process, and it can be completed only through conventional steps such as stirring, ultrasonic treatment, microwave treatment, and low-temperature drying. By optimizing process parameters, such as the power and time of microwave treatment, the temperature of activation and mixing, etc., the production cost can be significantly reduced while ensuring the performance of the dressing. This simple and economical preparation process is not only convenient for laboratory research and development but also suitable for large-scale industrial production, making the dressing have a high cost performance in the market, benefiting a wider range of patient groups, and promoting its popularization and application in clinical practice. In addition to the basic functions of antibacterial and promoting wound healing, the dressing of the present invention also has a variety of additional characteristics, further enhancing its application value. For example, the hemostatic effect of chitosan can quickly coagulate blood when the wound bleeds, shortening the hemostasis time; the moisturizing property of polyvinyl alcohol not only helps to maintain a moist environment but also reduces the pain of patients when changing the dressing; the antioxidant ability of selenium nanoparticles can reduce the inflammatory reaction at the wound site, alleviating local redness, swelling, and pain. These multifunctional characteristics make the dressing perform excellently in dealing with acute wounds (such as burns and cuts) and chronic wounds (such as diabetic foot ulcers), meeting the needs of different types of wound repair and having high clinical flexibility. The dressing of the present invention has good flexibility and conformability, can closely adhere to the skin surface, and adapt to wounds of different parts and shapes. By adjusting the mold shape and solidification conditions, the dressing can be easily cut and formed, facilitating the operation of medical staff. Its moist texture reduces the adhesion to the wound, avoiding the tearing damage to the newly formed tissue when changing the dressing, thus reducing the pain of patients and improving the comfort of use. In addition, the dressing still maintains a certain elasticity and toughness after solidification and is not easily displaced or fallen off due to the activities of patients, ensuring the stability and reliability during the treatment process. The dressing of the present invention pays attention to environmental friendliness during the preparation and use processes. The selected materials are all biodegradable or have less impact on the environment, such as chitosan can be gradually decomposed in the natural environment. The use of toxic solvents or heavy metals is avoided in the preparation process, reducing the potential hazards to the environment and operators. In addition, the dressing is easy to handle after use and does not produce medical waste that is difficult to degrade, meeting the development trend of green environmental protection of modern medical products.Combining the above advantages, the dressing of the present invention performs excellently in terms of antibacterial performance, tissue regeneration ability, mechanical strength, biocompatibility, and ease of use, and can effectively address various challenges in skin wound repair. Its remarkable antibacterial effect and wound healing promotion function are particularly suitable for wounds with high infection risk or slow healing, such as burns, ulcers, and postoperative wounds. At the same time, the simple preparation process and economical production cost endow it with the potential for large-scale promotion, and it is expected to replace some traditional dressings in the medical field and become the preferred choice for the new generation of wound repair materials.

[0016] In summary, the present invention provides a dressing for skin wound repair and its preparation method. Through the combination of nanomaterials and hydrogel technology, the comprehensive optimization of performance is achieved. The dressing not only has excellent antibacterial performance and tissue regeneration ability, but also has good mechanical strength, biocompatibility, versatility, and ease of use. At the same time, the preparation process is simple and economical, suitable for clinical promotion and application. This innovative technology provides an efficient, safe, and economical solution for skin wound repair, with significant social benefits and broad market prospects.

[0017] The advantages of the present invention will be partially elucidated in the following description, some are obvious based on the description, or can be learned through the implementation of the embodiments of the present invention. Brief Description of the Drawings

[0018] To more clearly elaborate on the content of the present invention, the following will be described in detail in combination with the drawings and specific embodiments.

[0019] Figure 1 It is the scanning electron microscope image of the product prepared in Example 3 of the present invention.

[0020] Figure 2 It is the real photo image of the product prepared in Example 3 of the present invention.

[0021] Figure 3 It is the wound healing image of the products prepared in Example 3 and Comparative Examples 1 - 5 of the present invention. Detailed Description of the Embodiments

[0022] The following are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements are also regarded as the protection scope of the present invention. At the same time, for the values in the unlimiting scope.

[0023] Example 1

[0024] Preparation method of dressing for skin wound repair, comprising the following steps by weight: Dissolve 0.2 parts of copper nitrate in 20 times its mass of distilled water, and then gradually add an aqueous sodium hydroxide solution 15 times the mass of copper nitrate, wherein the concentration of the aqueous sodium hydroxide solution is 0.5 M, continuously stir for 20 min to obtain a mixed system. The mixing and stirring method is to stir while ultrasonicating, wherein the stirring method is mechanical stirring, the rotation speed of the mechanical stirring is 200 rpm, the ultrasonicating method is water bath ultrasonicating, the power of the water bath ultrasonicating is 200 W, and the temperature of the water bath ultrasonicating is 55 °C. Gradually add 5 times the mass of copper nitrate of ethylenediamine and 20 times isophorone diamine to the mixed system. The dropping speed of ethylenediamine is 0.5 mL / min, and the dropping speed of isophorone diamine is 0.5 mL / min. Perform microwave treatment and activate and mix evenly. The power of the microwave treatment is 500 W, the time of the microwave treatment is 20 min, the temperature of the activation and mixing is 40 °C, and the time of the activation and mixing is 4 h. Then add an ethanol solution with a mass percentage of 70% 40 times the mass of copper nitrate, and vacuum dry at 50 °C for 24 h to obtain nanospheres; Next, dissolve 0.02 parts of selenium nanoparticles in 50 times its mass of acetone, and ultrasonicate for 1 h to obtain a nano-dispersion; Then, mix the nanospheres, the nano-dispersion and the emulsifier according to a volume ratio of 1:5:0.5. The emulsifier is Tween 20, stir at 50 °C for 80 min, separate the product by high-speed centrifugation, and then wash with acetone and sterilized water in sequence. The rotation speed of the high-speed centrifugation is 6000 rpm, the temperature of the high-speed centrifugation is 4 °C, and the time of the high-speed centrifugation is 15 min. Dry at -50 °C for 20 h to obtain a composite material; Finally, mix the above composite material and polyvinyl alcohol according to a weight ratio of 0.02:2, add deionized water 15 times the mass of polyvinyl alcohol, heat to 80 °C and stir for 4 h, then add chitosan 0.5 times the mass of polyvinyl alcohol, adjust the pH value to 5. The method of adjusting the pH value is to dropwise add a hydrochloric acid solution, stir at 50 °C for 30 min, then quickly add a crosslinking agent and an ammonium salt solution. The final mass percentage of the crosslinking agent is 1%, the crosslinking agent is glutaraldehyde, the final mass percentage of the ammonium salt solution is 5%, the ammonium salt solution is ammonium chloride solution, pour it into a mold, and obtain it after solidification. The solidification temperature is 4 °C.

[0025] Example 2

[0026] Preparation method of dressing for skin wound repair, comprising the following steps by weight: Dissolve 0.8 parts of copper nitrate in 10 times its mass of distilled water, and then gradually add an aqueous sodium hydroxide solution 30 times the mass of copper nitrate, wherein the concentration of the aqueous sodium hydroxide solution is 0.5 M, continuously stir for 10 min to obtain a mixed system. The mixing and stirring method is to stir while ultrasonically treating, wherein the stirring method is mechanical stirring, the rotation speed of the mechanical stirring is 200 rpm, the ultrasonic treatment method is water bath ultrasonic treatment, the power of the water bath ultrasonic treatment is 300 W, the temperature of the water bath ultrasonic treatment is 30 °C. Gradually add 10 times the mass of ethylenediamine and 10 times isophorone diamine of copper nitrate to the mixed system. The dropping speed of ethylenediamine is 1 mL / min, and the dropping speed of isophorone diamine is 0.25 mL / min. Perform microwave treatment and activate and mix evenly. The power of the microwave treatment is 800 W, the time of the microwave treatment is 10 min, the temperature of the activation and mixing is 50 °C, and the time of the activation and mixing is 2 h. Then add an ethanol solution with a mass percentage of 60% 60 times the mass of copper nitrate, and vacuum dry at 60 °C for 10 h to obtain nanospheres; Next, dissolve 0.08 parts of selenium nanoparticles in 30 times its mass of acetone, and ultrasonically treat for 3 h to obtain a nano-dispersion; Then, mix the nanospheres, the nano-dispersion and an emulsifier according to a volume ratio of 1:2:0.5. The emulsifier is Tween 80, stir at 60 °C for 60 min, separate the product by high-speed centrifugation and then wash with acetone and sterilized water in sequence. The rotation speed of the high-speed centrifugation is 6000 rpm, the temperature of the high-speed centrifugation is 4 °C, and the time of the high-speed centrifugation is 15 min. Dry at -50 °C for 30 h to obtain a composite material; Finally, mix the above composite material and polyvinyl alcohol according to a weight ratio of 0.02:1, add deionized water 25 times the mass of polyvinyl alcohol, heat to 80 °C and stir for 2 h, then add chitosan 1 time the mass of polyvinyl alcohol, adjust the pH value to 5. The method of adjusting the pH value is to dropwise add a hydrochloric acid solution, stir at 50 °C for 30 min, then quickly add a crosslinking agent and an ammonium salt solution. The final mass percentage of the crosslinking agent is 1%, the crosslinking agent is sorbitol, the final mass percentage of the ammonium salt solution is 5%, the ammonium salt solution is ammonium carbonate solution, pour it into a mold, and obtain it after solidification. The solidification temperature is 4 °C.

[0027] Example 3

[0028] Preparation method of dressing for skin wound repair, comprising the following steps by weight: Dissolve 0.5 part of copper nitrate in 15 times its mass of distilled water, and then gradually add dropwise a sodium hydroxide aqueous solution 25 times the mass of copper nitrate, wherein the concentration of the sodium hydroxide aqueous solution is 0.5 M, continuously stir for 15 min to obtain a mixed system. The way of the said mixing and stirring is to stir while ultrasonically treating, wherein the stirring method is mechanical stirring, the rotation speed of the mechanical stirring is 200 rpm, the ultrasonic treatment method is water bath ultrasonic treatment, the power of the water bath ultrasonic treatment is 250 W, the temperature of the water bath ultrasonic treatment is 40 °C. Gradually add dropwise 8 times the mass of ethylenediamine and 15 times isophorone diamine of copper nitrate to the mixed system. The dropping speed of ethylenediamine is 0.8 mL / min, and the dropping speed of isophorone diamine is 0.4 mL / min. Perform microwave treatment and activation and mixing. The power of the said microwave treatment is 700 W, the time of the microwave treatment is 15 min, the temperature of the activation and mixing is 45 °C, and the time of the activation and mixing is 3 h. Then add an ethanol solution with a mass percentage of 65% 50 times the mass of copper nitrate, and vacuum dry at 55 °C for 18 h to obtain nanospheres. Then, dissolve 0.05 part of selenium nanoparticles in 40 times its mass of acetone, and ultrasonically treat for 2 h to obtain a nano-dispersion. Then, mix the nanospheres, the nano-dispersion and an emulsifier according to a volume ratio of 1:4:0.5. The said emulsifier is polyoxyethylene stearate, stir at 55 °C for 70 min, separate the product by high-speed centrifugation, and then wash with acetone and sterile water in sequence. The rotation speed of the high-speed centrifugation is 6000 rpm, the temperature of the high-speed centrifugation is 4 °C, and the time of the high-speed centrifugation is 15 min. Dry at -50 °C for 25 h to obtain a composite material. Finally, mix the above composite material and polyvinyl alcohol according to a weight ratio of 0.02:1.5, add deionized water 20 times the mass of polyvinyl alcohol, heat to 80 °C and stir for 3 h, then add chitosan 0.8 times the mass of polyvinyl alcohol, adjust the pH value to 5. The way of the said adjusting the pH value is to dropwise add a hydrochloric acid solution, stir at 50 °C for 30 min, then quickly add a crosslinking agent and an ammonium salt solution. The final mass percentage of the crosslinking agent is 1%, the said crosslinking agent is polyethylene glycol, the final mass percentage of the ammonium salt solution is 5%, the said ammonium salt solution is ammonium phosphate solution, pour it into a mold, and obtain it after solidification. The solidification temperature is 4 °C.

[0029] Comparative Example 1

[0030] The technical solution is basically the same as that of Example 3, the difference is: copper nitrate is not used.

[0031] Comparative Example 2

[0032] The technical solution is basically the same as that of Example 3, the difference is: ethylenediamine is not used.

[0033] Comparative Example 3

[0034] The technical solution is basically the same as that of Example 3, except that isophorone diamine is not used.

[0035] Comparative Example 4

[0036] The technical solution is basically the same as that of Example 3, except that gelatin is used to replace polyvinyl alcohol.

[0037] Comparative Example 5

[0038] The technical solution is basically the same as that of Example 3, except that the ammonium salt solution is not used.

[0039] Comparative Example 6

[0040] A 5% w / v polyvinyl alcohol hydrogel is used.

[0041] Comparative Example 7

[0042] A 10% w / v polyvinyl alcohol hydrogel is used.

[0043] Comparative Example 8

[0044] A 15% w / v polyvinyl alcohol hydrogel is used.

[0045] Testing scheme

[0046] The hydrogel prepared above is placed under an ultraviolet lamp for 1 h in advance for sterilization treatment to ensure that the hydrogel is in a sterile state.

[0047] (1) Swelling ratio test: Weigh the dressing (hydrogel sample) after vacuum drying at 60 °C for 24 h, record the dry weight, soak the sample in deionized water at room temperature until swelling equilibrium is reached, take out the sample, gently blot the surface moisture with filter paper, weigh to obtain the mass after swelling, record the wet weight, and calculate the swelling ratio.

[0048] Table 1 Swelling ratio test results

[0049]

[0050]

[0051] (2) Characterization test: As Figure 1 shown, it shows the scanning electron micrograph of the dressing prepared in the best Example 3 of the present application. The average pore size of the dressing is 98.3 μm, and the pore distribution of the dressing is relatively uniform. It can be seen that the crosslinking degree inside the dressing is good and the mechanical properties are good. At the same time, a real photo was taken, as Figure 2 shown. The whole dressing is relatively transparent, but due to the addition of substances such as nanospheres, the transparency is weak, but it has relatively good stretching effect.

[0052] (3) In vitro antibacterial test: Escherichia coli (ATCC8739) suspension and Staphylococcus aureus (ATCC29213) suspension with a concentration of 10 8 CFU / mL were incubated together with the dressings prepared in Examples 1 - 3 and Comparative Examples 1 - 8 at 37 °C for 18 h, where the mass percentage of the added dressing was 5%, and the bacterial residue rate was analyzed by the plate counting method. In vivo antibacterial test: 30 male Kunming mice, 4 weeks old, SPF level, with a body weight of 18 g - 25 g, were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. The Kunming mice were evenly divided into 3 groups of Examples, 1 group of Comparative Example 1, 1 group of Comparative Example 2, 1 group of Comparative Example 3, 1 group of Comparative Example 4, and 1 group of Comparative Example 5. The breeding temperature was 20 °C, the humidity was 55%, and the light condition was 12 h light / 12 h darkness. A scalpel was used to shave the hair on the back of the Kunming mice to form a wound with a diameter of 1 cm, and a suspension of Staphylococcus aureus (ATCC29213) with a concentration of 10 6 CFU / mL was evenly applied at the wound position, and at the same time, dressings of the same size as the wound were respectively applied. After 9 days, pictures of the wounds were taken.

[0053] The bacterial residue rates of Examples 1 - 3 were 4.2%, 3.1%, and 2.5% respectively, and the bacterial residue rates of Comparative Examples 1 - 8 were 34.5%, 25.1%, 40.6%, 27.9%, 38.4%, 48.9%, 53.2%, and 59.7% respectively. In addition, as Figure 3 shown, it can be seen that compared with the dressings prepared in Comparative Examples 1 - 5, Example 3 of this application has a better healing effect on the wounds of Kunming mice.

[0054] Combined with the test results of the examples and comparative examples, the functions of each component in the skin wound repair dressing can be analyzed as follows: Copper nitrate is a key component for preparing copper-based nanospheres, providing a source of copper ions. The copper-based nanospheres have significant antibacterial properties, and they effectively inhibit the growth of pathogenic bacteria (such as Staphylococcus aureus and Escherichia coli) by disrupting the bacterial cell membrane and interfering with the metabolic process. Comparative example 1 (without using copper nitrate) showed a significantly higher bacterial residue rate (34.5%), indicating that copper nitrate is crucial for enhancing antibacterial properties. Two components, ethylenediamine and isophorone diamine, act as complexing agents in the preparation of nanospheres, helping to form a stable nanostructure and enhancing antibacterial activity. Comparative example 2 (without using ethylenediamine) and comparative example 3 (without using isophorone diamine) both showed higher bacterial residue rates (25.1% and 40.6% respectively), further verifying their importance in antibacterial properties. Selenium nanoparticles are a broad-spectrum antibacterial material with redox properties, capable of disrupting the bacterial cell membrane and reducing inflammatory responses, while promoting cell proliferation and tissue regeneration. The dressing with selenium nanoparticles added in the examples showed the lowest bacterial residue rate (such as 2.5% in example 3), significantly superior to the comparative examples without selenium added. Polyvinyl alcohol, as a matrix material, provides a three-dimensional network structure, endowing the dressing with excellent moisture retention performance and mechanical strength. Compared with comparative example 4 (using gelatin instead of PVA) and comparative examples 6 - 8 (only using PVA hydrogels with different concentrations), the PVA matrix dressing in the examples showed a higher swelling rate and better mechanical properties. Chitosan is a natural polymer material with good biocompatibility, hemostatic effect, and the ability to promote tissue repair. Its amino and hydroxyl groups interact with cells, stimulating tissue regeneration. The comparative example dressings without chitosan were significantly inferior in terms of tissue healing speed. Crosslinking agents (such as glutaraldehyde, sorbitol, or polyethylene glycol) and ammonium salt solutions (such as ammonium chloride, ammonium carbonate, or ammonium phosphate) act together to form a stable hydrogel network structure, improving the mechanical strength and flexibility of the dressing. Comparative example 5 (without using ammonium salt solution) showed a lower swelling rate and poorer healing effect, verifying the importance of crosslinking treatment. The nanospheres enhance the antibacterial properties and mechanical strength of the dressing through their special structure, while emulsifiers (such as Tween 20, Tween 80, etc.) help to uniformly disperse the nanoparticles, improving the uniformity of the composite material. The test results show that the synergistic effect of each component in the dressing significantly optimizes its performance, having obvious advantages compared with traditional dressings. In addition, for the nanosphere material, the addition of ethylenediamine and isophorone diamine not only plays a skeletal role, but also participates in the following processes: Ethylenediamine (EDA) as a bidentate ligand, EDA forms a stable chelate with copper ions through two amino groups, promoting the directional growth of the nanosphere core; in the microwave treatment stage (power 500 - 800 W), the coordination effect of EDA accelerates the dissolution-recrystallization process of the colloid, forming uniform nanospheres. Isophorone diamine (IPDA): Its cyclic structure and steric hindrance effect enhance the coordination selectivity.The amino group of IPDA forms a four-tooth coordination with copper ions, inhibiting the aggregation of nanospheres and regulating the surface charge distribution through the hydrophobic ring structure (the Zeta potential increases from -15 mV to +25 mV), improving the colloidal stability of the nanospheres.

[0055] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent of the present invention shall be subject to the appended claims.

Claims

1. A method for preparing a dressing for skin wound repair, characterized in that: The method comprises the following steps by weight: dissolving 0.2-0.8 parts of copper nitrate in distilled water with a mass of 10-20 times the mass of copper nitrate, then dropwise adding a sodium hydroxide aqueous solution with a mass of 15-30 times the mass of copper nitrate, wherein the concentration of the sodium hydroxide aqueous solution is 0.5M, continuously stirring for 10-20 minutes, mixing and stirring to obtain a mixed system, dropwise adding ethylenediamine with a mass of 5-10 times the mass of copper nitrate and isophoronediamine with a mass of 10-20 times the mass of copper nitrate to the mixed system, microwave treatment and activation and mixing, then adding a 60%-70% ethanol solution with a mass percentage of 40-60 times the mass of copper nitrate, and vacuum drying at 50°C-60°C for 10h-24h to obtain nanospheres; then, dissolving 0.02-0.08 parts of selenium nanoparticles in acetone with a mass of 30-50 times the mass of copper nitrate, ultrasonic treatment for 1h-3h, and obtaining nanospheres. dispersion; then, the nanospheres, nano dispersion and emulsifier are mixed in a volume ratio of 1: (2-5): 0.5, stirred at 50°C-60°C for 60min-80min, the product is separated by high-speed centrifugation, washed with acetone and sterilized water in turn, and dried at -50°C for 20h-30h to obtain a composite material; finally, the composite material is mixed with polyvinyl alcohol in a weight ratio of 0.02: (1-2), and deionized water with a mass of 15 to 25 times that of the polyvinyl alcohol is added, heated to 80°C and stirred for 2h-4h, and then chitosan with a mass of 0.5 to 1 times that of the polyvinyl alcohol is added, the pH value is adjusted to 5, stirred at 50°C for 30min, and then a cross-linking agent and an ammonium salt solution are quickly added, the final mass percentage of the cross-linking agent is 1%, and the final mass percentage of the ammonium salt solution is 5%, poured into a mold, and solidified to obtain.

2. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The emulsifier is at least one of Tween 20, Tween 80 and polyoxyethylene stearate; the cross-linking agent is at least one of glutaraldehyde, sorbitol and polyethylene glycol.

3. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The method for adjusting the pH value is to drip a hydrochloric acid solution; the ammonium salt solution is at least one of an ammonium chloride solution, an ammonium carbonate solution, and an ammonium phosphate solution.

4. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The mixing and stirring method is stirring and ultrasonicating, wherein the stirring method is mechanical stirring, wherein the speed of the mechanical stirring is 200rpm, wherein the ultrasonicating method is water bath ultrasonicating, wherein the power of the water bath ultrasonicating is 200W-300W, wherein the temperature of the water bath ultrasonicating is 30℃-55℃.

5. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The dropwise addition rate of ethylenediamine is 0.5 mL / min to 1 mL / min, and the dropwise addition rate of isophoronediamine is 0.25 mL / min to 0.5 mL / min.

6. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The power of the microwave treatment is 500W-800W, and the time of the microwave treatment is 10min-20min.

7. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The activation mixing temperature is 40°C-50°C, and the activation mixing time is 2h-4h.

8. The method for preparing a dressing for skin wound repair according to claim 1, characterized in that: The speed of high-speed centrifugation is 6000 rpm, the temperature of high-speed centrifugation is 4°C, the time of high-speed centrifugation is 15 minutes, and the coagulation temperature is 4°C.

9. A dressing prepared by the preparation method according to any one of claims 1 to 8.

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