Antibacterial Activity And Antibacterial Mechanism Of Ag/TiO₂ Nanoparticles

With the rapid development of economy and science and technology,people are confronted with various environmental problems while enjoying a more convenient life.People pay more and more attention to the comfortable environment and physical health.Therefore,more and more people researchers and companies are beginning to pay attention to the research and development of environmental protection and antibacterial materials.In recent years,inorganic antimicrobial agents have been extensively conducted due to their safety,long-lasting and broad-spectrum.Among them,titanium dioxide antimicrobial agents and silver antimicrobial agents are widely used.However,silver antibacterial agents have high price,easy discoloration and poor antibacterial efficacy.Titanium dioxide antibacterial agents need ultraviolet light irradiation and their antibacterial effect is weak.In order to overcome these shortcomings,the antibacterial activity can be enhanced by compounding inorganic antibacterial agents.In this paper,with silver ions as the doping element,Ag/TiO2 nanocomposites were prepared by sol-gel method and precipitation method.The microscopic properties of the samples were characterized by XRD and XPS.The antibacterial properties of the materials were tested by qualitative and quantitative methods.The influences of various factors on the antibacterial properties were discussed.The antibacterial mechanism was further studied.The results show that the prepared nanocomposite has the advantages of small particle size,good stability,less amount of Ag,and lower cost of materials.The silver-doped does not change the anatase structure of TiO2,and the silver exists in the form of elemental silver.Taking into account economic benefits,silver-doped titanium dioxide antibacterial agent have the best antibacterial effect under 1%silver concentration and 350 ? heat treatment temperature,antibacterial rate of 96%or more;Silver-doped titanium dioxide antibacterial agent shows good antibacterial performance in dark place and incandescent lamp,almost unaffected by the light source;Experiments show that silver ions are completely doped in the antibacterial agent and no Ag+ precipitates in the bacterial suspension.Combined with the existing antibacterial theory,we infer the antibacterial mechanism of Ag/TiO2 antibacterial agents,that is.in contact with bacteria,the antibacterial agent and hydroxide ions,water,and oxygen adsorbed on the surface thereof are converted into highly reactive groups such as hydroxyl radicals · OH and active oxygen · O2-.These reactive groups serve as a medium,acts on the cells,destroys the bacterial tissues and causes the death of the bacteria.