Application Of Metformin Capped Cu₂（OH）₃Cl Two-dimensional Nanosheets In Chemodynamic And Promotion Of Wound Healing

Context:The abuse of antibiotics leads to serious drug resistance of bacteria and poses a serious threat to human health.In order to solve the problems and challenges caused by drug resistance of existing bacteria,people have carried out in-depth research on the search for new antibiotic components,the development of drug resistance inhibitors and the establishment of mass immunity.However,it is not enough to optimize the antibacterial effect only in the discovery and synthesis of antibiotics.We need to explore some new methods to inhibit bacteria and control the occurrence of bacterial infectious diseases.In recent years,researchers based on chemodynamic therapy（CDT）,through the Fenton/Fenton-like reaction to produce toxic hydroxyl radicals,used in biomedical fields,including cancer treatment,antibacterial and infectious disease treatment.Compared with other treatments,CDT has the advantages of higher catalytic performance of reactive oxygen species,low invasiveness and resistance to drug resistance.Although chemical kinetics has improved the therapeutic effect,there are still some unsolved problems,including low catalytic efficiency and poor biocompatibility,which affect the full potential of CDT.Therefore,it is of great significance to develop a simple and efficient CDT catalytic preparation.Objectives:Develop a simple and efficient CDT catalytic preparation,test its material structure,composition characterization and enzyme-like catalytic activity,study the in vitro antibacterial activity,principle and in vivo antibacterial ability,promote wound healing,and verify the biosafety of the material.Methods:Metformin（Met）modified CuOHCl-Met two-dimensional nanoflakes（CuOHCl-Met NSs）with chemical kinetic response and enzyme-like catalytic activity were prepared by one-pot method.The enzyme-like catalytic activity of CuOHCl-Met NSs was detected and analyzed.The antibacterial effect and mechanism of H₂O₂/CuOHCl-Met NSs system were studied by plate dilution coating method,bacterial live/dead fluorescence staining and scanning electron microscope observation.The biological safety of the material was verified by cytotoxicity test in vitro,hemolysis test and toxicity test in mice.The Staphylococcus aureus（S.aureus）infection model of skin wound in mice was used to confirm the antibacterial activity of H₂O₂/CuOHCl-Met NSs system in vivo and the ability to promote wound healing.Results:Metformin-modified CuOHCl-Met NSs can be used as a cascade catalytic nano-platform for the treatment of wound infection and skin regeneration.CuOHCl-Met NSs has regular morphology and uniform size,which can participate in the redox reaction of glutathione（GSH）and catalyze H₂O₂ to produce hydroxyl radical（·OH）.With the addition of Met,the nano-tablets achieved high antibacterial activity in vitro and in vivo through synergistic therapy.CuOHCl-Met NSs can effectively kill bacteria at low concentration(6μg m L^-1)and short treatment time（within 15 minutes）,showing a great advantage over CuOHCl NSs without Met.The results of in vivo experiments showed that CuOHCl-Met NSs accelerated wound healing and regeneration of skin infected by S.aureus.The results of biocompatibility test in vivo and in vitro showed that CuOHCl-Met NSs had good safety to cells and mice at antibacterial concentration.This work not only developed an efficient CDT nano-preparation as an alternative antimicrobial agent for the treatment of skin wound infection,but also provided an idea for discovering new drugs from old drugs.It further provides a new perspective for the treatment of oral bacterial infectious diseases.