Preparation Of Photoresponsive Antibacterial Hydrogel For Infected Wound Repair

Both acute and chronic wounds are susceptible to bacterial infection,which would delay the wound healing process.The fabrication of biocompatible hydrogels with antibacterial activity and capable of promoting wound healing is crucial for infected skin defect therapy.Graphite carbon nitride（g-C₃N₄）possesses good biocompatibility and photocatalytic antibacterial activities.In this dissertation,two multifunctional photocatalytic antibacterial hydrogels were constructed based on g-C₃N₄ and some natural polymers.The antibacterial properties of the hydrogels against gram-positive bacteria and negative bacteria were studied.In vitro and in vivo tests were further carried out to estimate the effects of hydrogels for infected wounds repair.Firstly,a multifunctional g-C₃N₄ nanosheets doped collagen-alginate hydrogel（Col-SA/g-C₃N₄）was developed for skin regeneration.The ultra-thin g-C₃N₄ nanosheets with a thickness of about 0.7 nm were exfoliated by acid etching and ultrasound treatment.The as-prepared g-C₃N₄ nanosheets were mixed with collagen/alginate solution and then the mixture was treated with calcium chloride to obtain the Col-SA/g-C₃N₄ hydrogel.The incorporation of g-C₃N₄ nanosheets resulted in an increase in mechanical property of the hydrogel.Col-SA/g-C₃N₄ hydrogel possessed good swelling property,which may provide a moist environment during wound healing.In vitro cytotoxicity assay suggested that Col-SA/g-C₃N₄ hydrogel exhibited good biocompatibility.Col-SA/g-C₃N₄ hydrogel exhibited visible-light driven photoresponsive antibacterial activity against both gram positive and negative bacteria.In vivo wound healing experiment illustrated that the hydrogel could accelerate the healing of infected wound.Secondly,Ag nanoparticles/g-C₃N₄（Ag NPs/g-C₃N₄,ACN）were obtained by in-situ deposition of silver nanoparticles on g-C₃N₄ nanosheets.Herein,chitosan（CS）,dopamine（DA）,Col and ACN were employed to prepare collagen-chitosan-based hydrogels（Col-CS-DA/ACN）through the oxidation of ammonium persulfate.Col-CS-DA/ACN hydrogel possessed excellent self-healing and tissue adhesive properties.Col-CS-DA/ACN hydrogel showed excellent synergistic antibacterial properties against both gram positive and negative bacteria.Hemolysis and cytotoxicity assays demonstrated the good biocompatibility of Col-CS-DA/ACN hydrogel.Mice infected-wound model experiment illustrated that the hydrogel could inhibit wound bacterial infection and accelerate the healing process.