| Trauma and traumatic infection are usual cases in clinic.Various microorganisms can easily invade the wound site if properly protect was absent during the healing process,causing serious bacterial infections that inhibits the recovering of wound.In severe cases,tissue ulceration and even death may occur,causing physical pain and economic burden to patients.Medical dressings can act as a barrier for wounds,providing shelter and absorbing wound exudates,which would create favorable conditions for the rapid recovery of the wound.Traditional medical dressings show disadvantages such as simple structure and poor performance,low exudate absorption capacity,which is in urgent need of improvement.Moreover,timely replacement and cleaning is required during wound recovery.Ordinary dressing is easy to adhere to the wound,and it is easy to cause secondary trauma when changing,which has adverse effects on the healing of the wound.Hydrogel has high flexibility and biocompatibility,and its swelling performance is decent.It can absorb the exudate of the wound,provide a moist microenvironment for the wound,and accelerate the wound healing.Moreover,the hydrogel with sliding and elastic state is not easy to form rigid adhesion with the wound so as to avoid secondary injury during replacement and cleaning.Therefore,the development of easy-changing dressings with good barrier properties and antibacterial properties has become one of the research hotspots of biomedical materials.In this project,a series of drug-loaded hydrogel and hydrogel fiber materials were constructed based on chitosan and its derivatives,and their application potential as wound dressings was explored.Its morphological structure,swelling properties,water vapor transmission rate,hemolytic properties,cytotoxicity,antibacterial properties,and would healing rate had been systematically and deeply studied,and the main research contents and conclusions are as follows:（1）In order to construct the hydrogel dressings with antibacterial effect and biocompatibility,the natural materials gelatin（Gel）and chitosan（CS）were used as raw materials,and the natural antibacterial material Centella asiatica extract（CA）was added,and the gelatin/chitosan-loaded hydrogel（CA-Gel-CS-T）antibacterial dressing was prepared by immersion crosslinking.The crosslinking mechanism of hydrogels was studied in depth,and the microstructure,physicochemical properties,slow-release properties,antibacterial properties,cytotoxicity,hemolytic properties and wound healing effects of hydrogels were systematically explored.The mechanical performance test results show that the immersion strategy increases the compressive strength of the hydrogel by 10%～50%,the swelling rate was 480%,the water vapor transmission rate can reach 1982 g·m-2·d-1,the drug release last up to 216 h,the maximum cumulative release was about 74%,the maximum cell viability value was 1.27,and the hemolysis rate values were less than 5%,which has good biocompatibility and blood compatibility.It has strong bacteriostatic ability against S.aureus and E.coli.The results of the rat trauma model healing experiment showed that hydrogels containing CA helped to accelerate wound healing.Therefore,the hydrogel dressing has great application potential in wound healing and drug release.（2）The deformation ability of hydrogel materials constructed from natural materials is poor,in order to further improve the elongation properties of the materials,so that they can meet the application of joints,fingers and other parts.The design of interpenetrating network structure combines the biocompatibility advantages of natural polymer materials with the mechanical properties of synthetic polymer materials.Chitosan was grafted and modified into quaternary ammonium salt chitosan（QCS）with better water solubility and stronger antibacterial properties by epoxypropyltrimethylamine chloride（GTMAC）,and acrylamide（AM）was used as raw material and bioactive quercetin（QT）was added to construct a semi-interpenetrating network hydrogel dressing（QT-QCS-PAM）with good antioxidant and antibacterial properties by one-step method.The intersection of semi-interpenetrating network hydrogels was explored,and the effects of different QT concentrations and QCS concentrations on the micromorphology,mechanical properties,rheological properties,swelling properties,water vapor transmittance,hemolytic properties,cytotoxicity,antibacterial properties,antioxidant properties and wound healing of hydrogels were systematically explored.SEM results show that hydrogels have interconnected and uniformly sized porous structures.The mechanical performance test results show that QT-QCS-PAM hydrogel has good elasticity and toughness,and its elongation at break was as high as 800%.The swelling rate of the hydrogel was 565%,and the water vapor transmission rate was up to 2986 g·m-2·d-1.Under the synergistic effect of QT and QCS,the bacteriostatic rate was as high as 99.9%,the hemolysis rate value was less than 5%,the relative viability value of cells was as high as 1.6,and the free radical scavenging rate was up to 48.1%.Animal experiments have shown that hydrogels can accelerate wound healing.Therefore,the hydrogel has excellent antibacterial properties,good hemocompatibility,biocompatibility,antioxidant properties and accelerated wound healing.（3）Self-adhesive hydrogel dressings are easy to use and do not need to be bandaged,on the basis of QT-QCS-PAM semi-interpenetrating network hydrogel dressings,inspired by the adhesion properties of marine mussels,dopamine（DA）was added to the hydrogel to construct a multi-functional drug-loaded hydrogel（PDA-QT-QP）with self-adhesive properties.The micromorphological structure,mechanical properties,swelling properties and adhesion properties of the multifunctional hydrogel were systematically studied.The experimental results confirmed that the PDA-QT-QP hydrogel exhibited a uniform porous structure,and the pore size decreased with the increase of QT and DA dosage（the minimum pore size was 0.5μm）.The hydrogel has high water absorption（swelling rate up to 780%）,adheres to the surface of different materials,adhesion strength was about 10 KPa,and has good clearability and high tensile strain（up to 1800%）.The antioxidant performance of hydrogel can reach 67.3%,which can remove excess active oxygen species on the wound surface,reduce inflammation and damage to cells.The hemolysis rate of the hydrogel was less than 5%,and the relative cell viability value was as high as 1.62,showing excellent hemocompatibility and cytocompatibility.The bacteriostatic rate of the samples was close to 99.99%,which could effectively inhibit the reproduction of bacteria at the wound.Animal experiments have shown that hydrogels can effectively accelerate wound healing,and the wound healing rate was close to 100%on day 14.PDA-QT-QP hydrogel has good hemocompatibility,high antibacterial activity and wound healing effect,and shows great application potential in the field of wound dressings.（4）In order to improve the controllability and processability of hydrogel molding and improve the breathability and water permeability of hydrogel dressings,this topic explores the technical route of preparing bulk hydrogel into hydrogel fiber,and further uses hydrogel fiber to construct hydrogel nonwoven materials.Combined with the flexible drafting technology of water vortex,the continuous preparation of hydrogel fibers was realized.Subsequently,the fiber is crushed,wet networking,freeze-dried,silk fibroin（SF）crosslinking,secondary freeze-drying molding and other processes to obtain hydrogel fiber nonwoven material（QT-SQP-SF）with oxidation resistance and antibacterial properties.The experimental results show that the water vapor transmittance of all hydrogel nonwoven materials is higher than 2000 g·m-2·d-1,the hemolysis rate was less than 5%,the BCI value is between 15%～40%,the relative cell viability value can reach 2.13,the free radical scavenging rate of the sample can reach 86%,the hydrogel fiber nonwoven materials before and after SF reinforcement have good antibacterial activity,and the animal results show that the hydrogel fiber nonwoven material can effectively improve the wound healing speed.And the sample containing QT has a large healing rate.In summary,hydrogel fiber nonwoven materials have excellent hemocompatibility,coagulation capacity,cytocompatibility,antioxidant and antibacterial properties and accelerated wound healing effects,and have broad application prospects as wound dressings. |
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