Study On The Antibacterial Mechanism Of Ce/Ag/ZnO Nanocomposites Induced Oxidative Stress In Oral Bacteria

Objective: To explore the antibacterial mechanism of oxidative stress of nano-c omposite Ce/Ag/ZnO against common oral bacteria(Saccharomyces albicans ATCC90028),and to provide theoretical basis for the application of such inorganic nano-an tibacterial agents in the treatment of oral diseases.Methods: In this study,Ce/Ag/ZnO nanocomposites were diluted into solutions with concentrations of 0.625 mg/mL,0.313 mg/mL,0.156 mg/mL,0.078 mg/mL and 0.039mg/mL by double dilution method.The MIC and MBC of the nanocomposites against Saccharomyces albicans were detected by turbidimetric method and agar culture method.The growth curve of bacteria treated with different concentrations of Ce/Ag/ZnO antibacterial agent was plotted.Scanning electron microscopy(SEM)was used to observe the morphological changes of the bacterial surface when the material was co-cultured with fungal cells.Reactive oxygen species(ROS)detection kit,malondialdehyde(MDA)detection kit and catalase(CAT)detection kit were used to determine the ROS level of reactive oxygen species,the degree of lipid peroxidation(LPO)and catalase activity value when this material acted on the experimental bacteria.Results: The minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of Ce/Ag/ZnO nanocomposites against Saccharomyces albicans were0.156 mg/mL and 0.313 mg/mL respectively.It not only significantly inhibit the growth of bacteria,has the concentration dependence of its antibacterial effect,and scanning electron microscope(SEM)to observe it made a loss of Saccharomyces albicans cells form,characterized by cell shrinkage collapse,rough surface adhesion nanomaterials,fuzzy boundaries,the contents were leaked,causing serious damage of bacteria cell membrane.In addition,Ce/Ag/ZnO antibacterial agent can induce a large amount of ROS production in Saccharomyces albicans(P<0.05),and the content of ROS produced by Ce/Ag/ZnO antibacterial agent increases with the increase of antibacterial concentration.The degree of lipid peroxidation(LPO)to the experimental bacteria was also significantly higher than that of blank control group(P<0.05),indicating that the ROS caused serious damage to the lipid of Saccharomyces albicans,and the degree of damage to bacteria was positively correlated with the concentration of antimicrobial agents.The catalase activity value in fungus was significantly changed by the material(P<0.05),and the concentration and time of the material could affect the level of catalase activity value in fungus,which indirectly indicated that the elimination ability of ROS in the bacteria was related to the concentration and action time of antibacterial agents.Conclusion: This study proved that nano-materials still have good antibacterial effect after modification with rare earth,and revealed that nano-materials exert antibacterial effect by inducing oxidative stress reaction inside Saccharomyces albicans,which provides theoretical basis for studying the antibacterial mechanism of oxidative stress of inorganic nano-composites.