Antibacterial Property Of Au-Ag Bimetallic Nanoclusters

At present,the increase of drug resistance rate of bacteria caused by the overuse of antibiotics has posed a serious threat to human health.The rapid development of nanotechnology has brought new hope for the prevention and treatment of bacterial infection.Compared with antibiotics,metal nanoparticles-based antimicrobials have the merits of lower cost and less susceptibility to drug resistance.However,current metal nanoparticles-based antimicrobials usually suffer from complicated synthesis,low antibacterial activity,unclear antibacterial mechanism,and poor controllability.Therefore,this paper focused on the research and development of new,green,efficient,and controllable metal nanoparticles-based antimicrobials.We prepared zein-protected gold and silver bimetallic nanoclusters and systematically studied the antibacterial properties,antibacterial mechanism,and biosafety.The paper consisted of the following two parts:1.In the second part,Au Ag bimetallic nanoclusters（Z-Au Ag NCs）were prepared by using zein as both a reducing agent and protected ligand.The size of Z-Au Ag NCs was 4±0.5 nm.Under ultraviolet irradiation,the Z-Au Ag NCs showed bright red fluorescence with emission peaks at 442 nm and 655 nm.Z-Au Ag NCs had good stability under different temperatures（20-90℃）,storage time（0-50 d）,ultraviolet irradiation（0-6 h）,and ionic strength（10-500 m M）conditions.Hemolysis demonstrated that Z-Au Ag NCs had low cytotoxicity.In vitro antibacterial experiments showed that Z-Au Ag NCs had good antibacterial activity against both Escherichia coli（Gram-negative bacteria）and Staphylococcus aureus（Gram-positive bacteria）.Mechanism study indicated that Z-Au Ag NCs may bind to the surface of bacteria and destroy their structural integrity,contributing to the antibacterial activity of Z-Au Ag NCs.2.In the third part,the Z-Au Ag NCs was developed as visible light-driven antibacterial agents.It was found that Z-Au Ag NCs could mimic the activity of oxidase driven by visible light.Under visible light irradiation,Z-Au Ag NCs can catalyze the conversion of dissolved oxygen into·O₂^-and ¹O₂,thus further improving the antibacterial activity of Z-Au Ag NCs.In vitro,antibacterial results showed that Z-Au Ag NCs could significantly destroy bacterial structure after 15 minutes of visible light exposure,and showed good antibacterial activity against Escherichia coli,Staphylococcus aureus,and Methicillin-resistant Staphylococcus aureus.An animal wound infection model was established on the back of mice to explore the feasibility of using Z-Au Ag NCs for the treatment of acute infected wounds.The results showed that Z-Au Ag NCs could significantly inhibit the growth of wound bacteria,promote the healing of infected wounds,reduce the pro-inflammatory cytokines,and showed excellent biological safety.On this basis,a thin film with antibacterial activity was prepared by utilizing the film-forming property of zein,which provided new hope for the prevention and treatment of bacterial infectious diseases.