A chitosan-based wound adhesive for promoting healing and inhibiting scar formation and a preparation method thereof

Abstract

This invention discloses a chitosan-based wound adhesive for promoting healing and inhibiting scarring, and its preparation method. The adhesive employs a time-controlled release structure: an outer layer is a chitosan-Imperata cylindrica inflammatory response coating, and an inner layer is a polylactic acid-egg membrane, loaded with tranexamic acid and onion extract liposomes. Upon contact with wound exudate, the outer layer can solidify in situ in response to salt, rapidly stopping bleeding and relieving pain; in the acidic inflammatory microenvironment, the inner layer gradually degrades, with the egg membrane and tranexamic acid synergistically promoting epithelial regeneration and improving scar quality; onion extract inhibits excessive fibroblast proliferation and regulates orderly collagen deposition, preventing hypertrophic scars and pigmentation from the source. This invention primarily uses natural biomaterials, exhibiting excellent biocompatibility, and simultaneously achieves hemostasis, anti-inflammation, healing promotion, and scar inhibition throughout the entire treatment cycle, overcoming the shortcomings of traditional dressings such as uncontrollable drug release and limited functionality.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a chitosan-based wound adhesive that promotes healing and inhibits scarring, and its preparation method. Background Technology

[0002] Wound healing is a highly ordered physiological process that strictly follows the progression of the inflammatory, proliferative, and remodeling phases. The wound microenvironment and bioactivity requirements differ significantly at each stage: the inflammatory phase requires antibacterial and anti-inflammatory agents and free radical scavenging; the proliferative phase requires promoting epithelial regeneration and angiogenesis; and the remodeling phase requires regulating collagen deposition and inhibiting excessive fibrosis. Ideal topical wound dressings not only need to provide a physical barrier, maintain a moist environment, and promote tissue regeneration, but also should possess good biocompatibility, biodegradability, and functional activity specific to each healing stage. Traditional dressings, such as gauze, often have poor adhesion or pose a risk of secondary damage, and their function is limited.

[0003] Chitosan, a natural cationic polysaccharide, has become a research hotspot in the field of biomedical materials due to its excellent biocompatibility, biodegradability, hemostatic properties, and antibacterial activity. The numerous amino and hydroxyl groups on its molecular chain provide active sites for chemical modification, making its functionalization possible. Chitosan grafted with protocatechuic aldehyde to construct a P-π conjugated structure and introducing metal-phenol coordination enables salt-responsive in-situ curing, making it an ideal substrate for medical wound adhesives. However, current similar materials still suffer from core defects: The release timing is uncontrollable, and it is impossible to accurately release the corresponding active factors according to the healing stage, which easily leads to burst release or delayed release and low drug utilization. The components have a single function, mostly single antibacterial or healing-promoting components, which cannot synergistically address multiple pathological changes such as inflammation, regeneration, and fibrosis. Scar prevention is insufficient, and there is a lack of a targeted mechanism to actively regulate collagen deposition and fibrosis during the remodeling period, which easily leads to hypertrophic scars and pigmentation after healing.

[0004] Tranexamic acid can inhibit pigmentation and excessive fibrin deposition, onion extract can inhibit abnormal proliferation of fibroblasts and soften disordered collagen, and the inner membrane of an egg is rich in natural collagen, elastin and hyaluronic acid, which can promote the regeneration of regular epithelium. Summary of the Invention

[0005] The technical problem to be solved: This invention constructs a staged controlled-release system. The outer chitosan coating is infused with Imperata cylindrica to enhance hemostasis and analgesia. The inner layer uses polylactic acid and eggshell inner membrane composite electrospun into a porous network, loaded with tranexamic acid, and contains onion extract liposomes in the core. This achieves precise drug release according to the healing stage, realizing hemostasis, analgesia, antibacterial and anti-inflammatory effects, promoting healing, and inhibiting scarring. It simultaneously addresses multiple pathological changes in the wound, solving problems such as the inability of wound adhesives to synergistically address multiple pathological changes including inflammation, regeneration, and fibrosis, as well as insufficient scar prevention.

[0006] Technical solution: A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring, comprising the following steps: S1. Onion extract liposomes: Onion extract was dissolved in phosphate buffer to obtain an onion extract solution, soybean lecithin ethanol solution was added, the mixture was ultrasonically dispersed and homogenized, and then nitrogen purged to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: Eggshell inner membrane is washed, homogenized with water to obtain eggshell inner membrane homogenate, polylactic acid is added and mixed and homogenized, spray dried into mixed powder, organic solvent is added and stirred to prepare spinning solution, porous network is prepared by electrospinning, tranexamic acid is dissolved in deionized water, porous network is immersed in tranexamic acid solution, ultrasonic treatment is followed by isothermal adsorption to obtain intermediate layer loaded with tranexamic acid; S3. Wound adhesive: Add fine powder of Imperata cylindrica flower to the grafted modified chitosan solution, stir evenly to form a coating liquid, immerse the intermediate layer loaded with tranexamic acid in the onion extract liposome suspension, stir thoroughly, place the treated intermediate layer in the chitosan-Imperata cylindrica flower coating liquid, shake and soak, and dry to form a film to obtain the wound adhesive.

[0007] Furthermore, in step S1, the mass ratio of onion extract to soybean lecithin is 1:(2-5), the buffer solution is a phosphate buffer with pH 7.0-7.4; the concentration of the onion extract solution is 1-2 wt.%; the concentration of the soybean lecithin ethanol solution is 2-3 wt.%; the ultrasonic dispersion conditions are: power 200-300W, ultrasonic 3s interval 2s, total duration 15-20 min; homogenization pressure is 600-800 bar.

[0008] Furthermore, in step S2, the ratio of eggshell inner membrane to water is 1:(30-50); the mass ratio of eggshell inner membrane homogenate, polylactic acid, and organic solvent is (20-30):(2-3):(30-50); the homogenization speed is 5000-8000 rpm, and the time is 3-5 min; the stirring speed is 500-800 rpm, the temperature is 30-40℃, and the time is 18-24 h; the electrospinning parameters are: voltage 15-18 kV, and feed speed 1.5-2.5 mL / h.

[0009] Furthermore, in step S2, the concentration of the tranexamic acid solution is 4-8 wt.%, the ultrasonic treatment power is 100-200W, and the time is 15-30 min; the isothermal adsorption temperature is 30-37℃, and the time is 12-16 h.

[0010] Furthermore, the organic solvent in step S2 is one or more of hexafluoroisopropanol, chloroform, and dichloromethane.

[0011] Furthermore, in step S3, the mass ratio of grafted modified chitosan to fine powder of Imperata cylindrica flower is (3-5):1; the concentration of the grafted modified chitosan solution is 3-5 wt.%; the stirring speed is 500-800 rpm, the stirring time is 3-5 h; and the stirring is carried out for 2-3 h.

[0012] Furthermore, the structural unit of the grafted and modified chitosan in step S3 is shown in the figure below:

[0013] Furthermore, the preparation method of grafted modified chitosan in step S3 is as follows: Step 1: Weigh out chitosan and dissolve it in 1% glacial acetic acid aqueous solution. Stir at room temperature until completely dissolved to prepare a 2-5 wt.% chitosan solution. Step 2: Dissolve protocatechuic aldehyde in anhydrous ethanol, add it dropwise to chitosan solution, and stir at room temperature for 3 hours; Step 3: Add sodium cyanoborohydride in batches, heat to 48℃, and react for 24 hours to allow protocatechuic aldehyde and chitosan amino groups to undergo a reduction amination reaction, forming stable secondary amine bonds and constructing a P-π conjugated system. Step 4: After cooling, add NaCl solution dropwise, stir to precipitate, filter, wash the precipitate successively with 1M NaOH solution, deionized water and ethanol, and dry under vacuum at 45℃ to obtain a brown solid product, which is grafted modified chitosan.

[0014] Furthermore, the chitosan in step 1 has a molecular weight of 3-1,000,000 and a degree of deacetylation of ≥85%.

[0015] Furthermore, in step 2, the molar ratio of protocatechuic aldehyde to chitosan amino is 1:(2-5).

[0016] Furthermore, in step 3, the molar ratio of sodium cyanoborohydride to protocatechuic aldehyde is (1-2):1.

[0017] A chitosan-based wound adhesive that promotes healing and inhibits scarring, prepared by any of the above preparation methods.

[0018] Furthermore, the wound adhesive has salt-responsive properties.

[0019] The above-described chitosan-based wound adhesive that promotes healing and inhibits scarring is used in the preparation of wound adhesive materials.

[0020] Beneficial effects: This invention grafts protocatechuic aldehyde onto a chitosan backbone with a stable secondary amine bond, and utilizes the lone pair electrons of the nitrogen atom in the secondary amine bond and the π electron cloud of the benzene ring to construct a molecular-level P-π conjugated system. When the material comes into contact with wound exudate rich in electrolytes, salt ions disrupt the hydration layer around the material, inducing charge rearrangement in the P-π conjugated system, while enhancing hydrophobic interactions, achieving rapid in-situ solidification and enhanced adhesion. This mechanism realizes "active utilization" of wound exudate rather than "passive resistance".

[0021] This invention accelerates material degradation by dissociating coordination bonds in an acidic inflammatory microenvironment, allowing the inner functional substances to begin functioning. Polylactic acid (PLA), acting as a framework, not only provides excellent mechanical strength for the wound adhesive but also offers physical support for cell adhesion, proliferation, and migration. The protein inner membrane contains silk fibroin, collagen, and other proteins, which improve the hydrophilicity and cell affinity of the PLA material, creating a moist environment for healing, enhancing the bioactivity of the dressing, and accelerating skin regeneration. The loaded tranexamic acid promotes collagen synthesis and extracellular matrix formation, contributing to wound healing and tissue repair, improving scar formation quality, and reducing the risk of infection.

[0022] This invention uses onion extract as its core ingredient, which reduces the risk of scar hyperplasia from the source by inhibiting the excessive proliferation of fibroblasts and collagen synthesis. In addition, it can upregulate the expression of MMP-1, helping to degrade and remodel excess collagen fibers that have already formed. At the same time, its antioxidant and anti-inflammatory effects can also relieve problems such as pain, itching, and pigmentation caused by scars.

[0023] This invention utilizes a multi-layered, time-release design to precisely match the stages of wound healing. The outer chitosan-Imperata cylindrica coating can intelligently release drugs in response to the inflammatory microenvironment and quickly exert hemostatic and analgesic effects. The inner polylactic acid-eggshell inner membrane porous network slowly releases tranexamic acid, and the core releases onion extract. This solves the problems of disordered drug delivery and single function of traditional adhesives, simultaneously addressing multiple pathological changes in the wound, significantly improving the appearance after healing, reducing raised and hardened scars, and leaving no obvious traces after wound healing.

[0024] The core components of this invention are mainly natural biomaterials. Chitosan, eggshell membrane, onion extract, and Imperata cylindrica flower are all derived from nature. Polylactic acid is a biodegradable material with no harmful chemically synthesized components, excellent biocompatibility, and low irritation. It can reduce wound irritation and the risk of allergies, making it suitable for special groups such as sensitive skin and children. The porous network formed by electrospinning eggshell membrane and polylactic acid retains the epithelial regeneration properties of eggshell membrane while improving the mechanical stability of the fiber network. Attached Figure Description

[0025] Figure 1 This is the UV absorption spectrum of modified chitosan. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: Example 1

[0027] A method for preparing grafted modified chitosan includes the following steps: Step 1: Weigh chitosan (molecular weight 3-1 million, degree of deacetylation ≥85%) and dissolve it in 1% glacial acetic acid aqueous solution. Stir at room temperature until completely dissolved to prepare a 3% chitosan solution. Step 2: Dissolve protocatechuic aldehyde in anhydrous ethanol (molar ratio of protocatechuic aldehyde to chitosan is 1:3), add the chitosan solution dropwise, and stir at room temperature for 3 hours; Step 3: Add sodium cyanoborohydride in batches, with a molar ratio of sodium cyanoborohydride to protocatechuic aldehyde of 1:1. Heat to 48℃ and react for 24 hours to allow protocatechuic aldehyde to undergo a reducing amination reaction with chitosan amino groups, forming stable secondary amine bonds and constructing a P-π conjugated system. Step 4: After cooling, add NaCl solution dropwise and stir to precipitate. Filter and wash the precipitate successively with 1M NaOH solution, deionized water and ethanol. Dry under vacuum at 45℃ to obtain a brown solid product, which is the grafted modified chitosan. Comparative Example 1

[0028] The difference between this comparative example and Example 1 is that chitosan is modified with Schiff base, as detailed below: Step 1: Weigh chitosan (molecular weight 3-1 million, degree of deacetylation ≥85%) and dissolve it in 1% glacial acetic acid aqueous solution. Stir at room temperature until completely dissolved to prepare a 3% chitosan solution. Step 2: Dissolve protocatechuic aldehyde in anhydrous ethanol (molar ratio of protocatechuic aldehyde to chitosan is 1:3), add the chitosan solution dropwise, and stir at room temperature for 3 hours; Step 3: Heat to 48℃ and react for 24 hours to allow protocatechuic aldehyde to form C=N bonds with chitosan only through Schiff base reaction; Step 4: After cooling, add NaCl solution dropwise and stir to precipitate. Filter and wash the precipitate successively with 1M NaOH solution, deionized water and ethanol. Dry under vacuum at 45℃ to obtain a brown solid product, which is the grafted modified chitosan. Performance testing

[0029] Characterization of salt-responsive aggregation behavior (UV-Vis absorption spectroscopy) Test method: The modified chitosan prepared in Example 1 was dissolved in NaCl solutions of different concentrations (0 mM, 150 mM, 300 mM), and the absorption spectrum in the range of 200-800 nm was scanned using a UV-Vis spectrophotometer.

[0030] Test results are as follows Figure 1 As shown, the modified chitosan exhibits a characteristic absorption peak at 280 nm, attributed to the π→π* transition of the P-π conjugated system formed between the protocatechuic aldehyde benzene ring and the lone pair electrons of the nitrogen atom in the secondary amine bond, proving the successful construction of the P-π conjugated structure. With increasing salt concentration, the turbidity of the solution at 600 nm gradually increases. Under the condition of 150 mM NaCl (simulating the salt concentration of wound exudate), the turbidity increases significantly, indicating that the modified chitosan undergoes hydrophobic aggregation and phase separation behavior in a salt environment. This salt-induced aggregation effect is consistent with the salt-responsive in-situ solidification characteristics of this invention, providing a structural basis for the rapid adhesion and enhancement of the material after contact with wound exudate. Example 2

[0031] A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring includes the following steps: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Example 3

[0032] A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring includes the following steps: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 4g of polylactic acid was added and mixed at 5000rpm for 5min, and spray-dried into powder. 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution. A porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Example 4

[0033] A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring includes the following steps: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ for 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a tranexamic acid solution with a concentration of 8wt.%. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Example 5

[0034] A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring includes the following steps: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.3g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Example 6

[0035] A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring includes the following steps: S1. Onion extract liposomes: 2g of onion extract was dissolved in 98g of phosphate buffer to obtain an onion extract solution. 150g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Comparative Example 2

[0036] The difference between this comparative example and Example 1 is that unmodified chitosan is used, as detailed below: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: Add 0.5g of fine powder of Imperata cylindrica flower to 50g of 3wt.% chitosan solution, stir at 500rpm for 3h to form a uniform coating liquid, immerse the intermediate layer loaded with tranexamic acid in onion extract liposome suspension, stir thoroughly for 2h, place the treated intermediate layer in chitosan-imperata cylindrica flower coating liquid, shake and soak for 1h, dry to form a film to obtain wound adhesive. Comparative Example 3

[0037] The difference between this comparative example and Example 1 is the addition of the modified chitosan of Comparative Example 1, as detailed below: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: Comparative Example 1 grafted modified chitosan was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Comparative Example 4

[0038] The difference between this comparative example and Example 1 is that onion extract is not added, as detailed below: S1. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ for 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S2. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder, and stirred at 500rpm for 3h to form a uniform coating liquid. The intermediate layer loaded with tranexamic acid was placed in the chitosan-Imperata cylindrica flower coating liquid, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Comparative Example 5

[0039] The difference between this comparative example and Example 1 is that the inner membrane of the eggshell is not added, as detailed below: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid network: 6g of polylactic acid was added to 100g of hexafluoroisopropanol and stirred at 35℃ and 500rpm to prepare a spinning solution. A porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2h. The treated intermediate layer was placed in the chitosan-Imperata cylindrica flower coating solution, shaken and soaked for 1h, and dried to form a film to obtain the wound adhesive. Comparative Example 6

[0040] The difference between this comparative example and Example 1 is that it does not have the polylactic acid-eggshell inner membrane porous network, as detailed below: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. 50g of the solution was added to 0.5g of Imperata cylindrica flower powder and stirred at 500rpm for 3h to form a uniform coating liquid. The coating liquid was then added to the onion extract liposome suspension and stirred thoroughly for 2h. The mixture was then dried to form a film to obtain the wound adhesive. Comparative Example 7

[0041] The difference between this comparative example and Example 1 is that it does not contain fine powder of Imperata cylindrica flowers, as detailed below: S1. Onion extract liposomes: 1g of onion extract was dissolved in 99g of phosphate buffer to obtain an onion extract solution. 100g of 3wt.% soybean lecithin ethanol solution was added, and the mixture was dispersed by ultrasonication at 200W for 3s followed by 2s intervals. After ultrasonication for 15 min, the mixture was homogenized at 600 bar and purged with nitrogen to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: 1g of eggshell inner membrane was washed, 39g of water was added to homogenize the eggshell inner membrane to obtain an eggshell inner membrane homogenate, 6g of polylactic acid was added and mixed at 5000rpm for 5min, spray dried into powder, 100g of hexafluoroisopropanol was added and stirred at 35℃ and 500rpm to prepare a spinning solution, and a porous network was prepared by electrospinning. The electrospinning parameters were voltage 16kV and feed speed 2.0mL / h. Tranexamic acid was dissolved in deionized water to prepare a 5wt.% tranexamic acid solution. The porous network was immersed in the tranexamic acid solution, ultrasonically treated at 100W for 30min, and then adsorbed at 37℃ for 12h to obtain an intermediate layer loaded with tranexamic acid. S3. Wound adhesive: The grafted modified chitosan of Example 1 was prepared into a 3wt.% chitosan solution. The intermediate layer loaded with tranexamic acid was immersed in an onion extract liposome suspension and stirred thoroughly for 2 hours. The treated intermediate layer was placed in the chitosan solution, shaken and soaked for 1 hour, and dried to form a film to obtain the wound adhesive.

[0042] 1. Salt-responsive adhesion performance test (1) Test method: The materials of each embodiment were attached to the surface of pigskin (contact area 1 cm²), a slight pressure (5 kPa) was applied and held for 30 seconds, and then peeled vertically at a rate of 10 mm / min. The maximum peeling force was recorded.

[0043] (2) Salt concentration conditions: Tests were conducted in PBS buffer without salt and PBS buffer containing 150 mM NaCl, respectively, and the salt response enhancement factor was calculated. The calculation method is as follows:

[0044] Among them, F 150 mM NaCl : Average maximum peel force (N / cm) under 150 mM NaCl conditions. F 0 mM NaCl : Average maximum peel force (N / cm) under conditions without NaCl.

[0045] An enhancement factor greater than 1 indicates that the salt environment promotes adhesion enhancement; the higher the factor, the more significant the salt response characteristics.

[0046] Table 1. Adhesion strength (peel force, N / cm) of different materials under salt-free and 150 mM NaCl conditions.

[0047] The results are shown in Table 1: Comparative Example 4 (without onion extract) still retains the complete outer and inner layer structure, and the salt-responsive adhesion ability is strong, but slightly lower than that of Example 2, indicating that the onion extract has no negative impact on adhesion.

[0048] Comparative Example 5 (without egg inner membrane) has only a polylactic acid network, resulting in a denser structure and still good salt response, but with decreased biological activity. Comparative Example 6 (without polylactic acid-egg inner membrane porous network) has only a chitosan layer and liposomes, resulting in a loose structure and limited enhancement of salt response. Comparative Example 7 (without Imperata cylindrica flower) has a structure closest to Example 2, lacking only Imperata cylindrica flower, therefore its adhesive properties are similar, indicating that Imperata cylindrica flower does not contribute much to salt-responsive adhesion and mainly plays a hemostatic and analgesic role.

[0049] 2. Antibacterial performance test Test methods: The inhibition zone method and colony counting method were used. The materials of each example were co-cultured with Staphylococcus aureus and Escherichia coli for 24 h, and the diameter of the inhibition zone and the bacterial survival rate were measured.

[0050] Table 2 Antibacterial effects of different wound adhesives

[0051] The test results are shown in Table 2. Example 2 exhibited the best antibacterial activity, with inhibition zone diameters of 14.5 mm and 13.2 mm against S. aureus and E. coli, respectively, and bacterial survival rates of only 12.5% ​​and 18.3%. This indicates that the outer chitosan-Imperata cylindrica coating and the inner porous network structure synergistically exert a good broad-spectrum antibacterial effect.

[0052] Comparative Example 2 (unmodified chitosan) showed significantly reduced inhibition zones (9.0 mm and 8.2 mm), with survival rates increasing to 45.6% and 52.3%, indicating that grafting modification is crucial for improving antibacterial performance. Comparative Example 3 exhibited moderate antibacterial performance, demonstrating that the secondary amine bonds in the P-π conjugated structure are more stable and have stronger antibacterial activity. Comparative Examples 4, 5, and 7 showed slightly lower antibacterial performance than Example 2, indicating that onion extract, egg membrane, and Imperata cylindrica flower have limited contribution to antibacterial activity, and their functions lie in scar suppression, healing promotion, and analgesia, respectively. Comparative Example 6 (polylactic acid-free egg membrane porous network) showed the worst antibacterial performance, indicating that the porous structure helps improve the exposure and release efficiency of antibacterial substances.

[0053] In summary, the chitosan-based wound healing and scar-inhibiting adhesive constructed in Example 2 of this invention has good broad-spectrum antibacterial properties, mainly attributed to the strong cationic antibacterial mechanism of the P-π conjugated structure modified chitosan and the synergistic effect of the efficient exposure of the porous network.

[0054] Swelling performance test Test method: After drying and weighing the materials of each embodiment, they were immersed in 150 mM NaCl solution (simulating wound exudate), and were taken out and weighed at regular intervals to calculate the swelling rate.

[0055] Table 3. Swelling rates of different wound adhesives

[0056] The results are shown in Table 3. The swelling rate of Example 2 was 73.6%, which is at a moderate level, capable of absorbing wound exudate while maintaining structural integrity. A swelling rate that is too low (e.g., 58.2% in Example 3 and 54.3% in Example 5) would result in insufficient water absorption, making it difficult to effectively absorb wound exudate. A swelling rate that is too high (e.g., 92.8% in Comparative Example 2 and 120.5% in Comparative Example 6) would cause the material to expand excessively, leading to a loose structure, decreased mechanical properties, and even compression of the wound surface.

[0057] Example 2 achieves moderately controllable swelling behavior through the synergistic effect of modified chitosan and porous network, which can absorb excess exudate, maintain a moist healing environment, and maintain structural integrity and adhesion strength.

[0058] animal experiments The study investigated the analgesic and scar-inhibiting effects.

[0059] (1) Animal behavior hot plate test or tail flick test (acute pain), record pain threshold and latency period. The higher the value, the stronger the analgesia.

[0060] Acetic acid writhing test (chemically irritated pain): count the number of writhing episodes within 15 minutes. The fewer the number of writhing episodes, the stronger the analgesia. Calculate the analgesic inhibition rate.

[0061] As shown in Table 4, Example 2 had the fewest twisting movements (6.2 times) and the best analgesic effect. Comparative Example 7 (without Imperata cylindrica flowers) showed a significant reduction in pain threshold (9.5 s), proving that Imperata cylindrica flowers are the key analgesic component.

[0062] Table 4. Analgesic effects of different wound adhesives on mice.

[0063] (2) Wound healing rate, time to complete healing, and wound appearance score.

[0064] Area calculation based on timed photography: Healing rate = (Initial area - Remaining area) / Initial area × 100%; The faster the healing, the lower the risk of scarring.

[0065] Table 5 shows that Example 2 had the highest healing rate (98.5%), the shortest healing time (12.5 days), and the best appearance score (4.8 points). Comparative Example 5 (without egg membrane) had a healing rate of 90.3%, and Comparative Example 6 (without porous network) only 80.5%, demonstrating that the porous network and egg membrane are indispensable for promoting healing. The lower appearance score of Comparative Example 4 indicates that the onion extract played a role in inhibiting scarring.

[0066] Table 5 Healing effects of different wound adhesives

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for preparing a chitosan-based wound adhesive that promotes healing and inhibits scarring, characterized in that, Includes the following steps: S1. Onion extract liposomes: Onion extract was dissolved in phosphate buffer to obtain an onion extract solution, soybean lecithin ethanol solution was added, the mixture was ultrasonically dispersed and homogenized, and then nitrogen purged to obtain a liposome suspension. S2. Polylactic acid-eggshell inner membrane porous network: Eggshell inner membrane is washed, homogenized with water to obtain eggshell inner membrane homogenate, polylactic acid is added and mixed and homogenized, spray dried into mixed powder, organic solvent is added and stirred to prepare spinning solution, porous network is prepared by electrospinning, tranexamic acid is dissolved in deionized water, porous network is immersed in tranexamic acid solution, ultrasonic treatment is followed by isothermal adsorption to obtain intermediate layer loaded with tranexamic acid; S3. Wound adhesive: Add fine powder of Imperata cylindrica flower to the grafted modified chitosan solution, stir evenly to form a coating liquid, immerse the intermediate layer loaded with tranexamic acid in the onion extract liposome suspension, stir thoroughly, place the treated intermediate layer in the chitosan-Imperata cylindrica flower coating liquid, shake and soak, and dry to form a film to obtain the wound adhesive.

2. The method for preparing a chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 1, characterized in that: In step S1, the mass ratio of onion extract to soybean lecithin is 1:(2-5), the buffer solution is a phosphate buffer with pH 7.0-7.4; the concentration of the onion extract solution is 1-2 wt.%; the concentration of the soybean lecithin ethanol solution is 2-3 wt.%; the ultrasonic dispersion conditions are 200-300W power, 3s ultrasonication / 2s interval, total duration 15-20 min; the homogenization pressure is 600-800 bar.

3. The method for preparing a chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 1, characterized in that: In step S2, the ratio of eggshell inner membrane to water is 1:(30-50); the mass ratio of eggshell inner membrane, polylactic acid, and organic solvent is (20-30):(2-3):(30-50); the homogenization speed is 5000-8000 rpm, and the time is 3-5 min; the stirring speed is 500-800 rpm, the temperature is 30-40℃, and the time is 18-24 h; the electrospinning parameters are: voltage 15-18 kV, and feed speed 1.5-2.5 mL / h.

4. The method for preparing a chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 1, characterized in that: In step S2, the concentration of the tranexamic acid solution is 4-8 wt.%, the ultrasonic treatment power is 100-200W, and the time is 15-30 min; the isothermal adsorption temperature is 30-37℃, and the time is 12-16 h; the organic solvent is one or more of hexafluoroisopropanol, chloroform, and dichloromethane.

5. The method for preparing a chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 1, characterized in that: In step S3, the mass ratio of grafted modified chitosan to fine powder of Imperata cylindrica flower is (3-5):1; the concentration of the grafted modified chitosan solution is 3-5 wt.%; the stirring speed is 500-800 rpm, and the stirring time is 3-5 h; the stirring is carried out for 2-3 h; and the mixture is ultrasonically dispersed for 10 min.

6. The method for preparing a chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 1, characterized in that: The preparation method of grafted modified chitosan in step S3 is as follows: Step 1: Weigh out chitosan and dissolve it in 1% glacial acetic acid aqueous solution. Stir at room temperature until completely dissolved to prepare a 2-5 wt.% chitosan solution. Step 2: Dissolve protocatechuic aldehyde in anhydrous ethanol, add it dropwise to chitosan solution, and stir at room temperature for 3 hours; Step 3: Add sodium cyanoborohydride in batches, heat to 48℃, and react for 24 hours to allow protocatechuic aldehyde and chitosan amino groups to undergo a reduction amination reaction, forming stable secondary amine bonds and constructing a P-π conjugated system. Step 4: After cooling, add NaCl solution dropwise, stir to precipitate, filter, wash the precipitate successively with 1M NaOH solution, deionized water and ethanol, and dry under vacuum at 45℃ to obtain a brown solid product, which is grafted modified chitosan.

7. The method for preparing a chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 6, characterized in that: In step 1, the chitosan has a molecular weight of 3-1,000,000 and a degree of deacetylation of ≥85%; in step 2, the molar ratio of protocatechuic aldehyde to chitosan amino group is 1:(2-5); in step 3, the molar ratio of sodium cyanoborohydride to protocatechuic aldehyde is (1-2):

1.

8. A chitosan-based wound adhesive for promoting healing and inhibiting scarring, prepared according to any one of claims 1-7.

9. A chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 8, characterized in that, The wound adhesive has salt-responsive properties.

10. The application of the chitosan-based wound adhesive for promoting healing and inhibiting scarring according to claim 8 in the preparation of wound adhesive materials.

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