Study On Cytotoxicity And Antibacterial Modification Of Nano Titanium Dioxide

At present,in the environment we contact,there are a variety of bacteria,all kinds of antibacterial materials become a research hotspot.Many pathogenic bacteria become more resistant to antibiotics and the number of harmful bacteria in the environment increases.Some antimicrobials,such as quaternary ammonium compounds,alcohols and phenols,have quick effects,poor stability and short validity periods,and will affect human health after long-term use.Photocatalytic nano-antibacterial materials do not produce drug resistance,good safety,low preparation cost,wide range of antibacterial,and have been extensively studied.However,nano powder is difficult to recover in practical application,which is easy to cause secondary pollution.Therefore,based on the existence of these problems,this paper uses nano titanium dioxide（nano-TiO₂）powder to prepare antibacterial coatings,so as to achieve efficient antibacterial performance of nano-TiO₂coatings.First,nano-TiO₂ coated fabrics with high photocatalytic antibacterial activity are successfully prepared by modified plate impregnation method,and the coated fabrics are characterized by SEM.It is found that nano-TiO₂ is uniformly and firmly deposited on the surface of the fabrics.The cytotoxicity of nano-TiO₂ is detected by flow cytometry in mouse fibroblasts.The safety of nano-TiO₂ in fabrics field is evaluated qualitatively and quantitatively.The results show that the inactivation rate of nano-TiO₂ coated fabric to Escherichia coli reached more than 90%within 1 h.The biotoxicity of nano-TiO₂ particles depends on its size and concentration.The apoptosis rate decreases with the increase of particle size.When the concentration of particles entering cells reaches 100μg/m L,the normal metabolism of cells will be affected,leading to cell apoptosis.The mechanism of cell apoptosis induced by nano-TiO₂ is also discussed.Then nano copper is used to modify existing nano-TiO₂,and TiO₂/Cu composite coating is prepared by liquid phase thermal spraying method.By adjusting the process parameters,the prepared composite coating well retains the anatase and rutile crystal phases of the original nano-TiO₂ particles,and no phase transformation occurs,which ensures the original photocatalytic activity.The addition of Cu nanoparticles enhanced the photo response and photocatalytic activity of the composite coating in the visible region.The inactivation rates of Escherichia coli and Staphylococcus aureus are above 95%and close to 100%when the amount of copper mixture is 2.5%and 5%.At the same time,the antibacterial mechanism of composite coating is investigated.The presence of nano copper increased the production of reactive oxygen species and enhanced the photocatalysis.Bacterial inactivation depends on enhanced photocatalysis and release of copper ions.TiO₂/Cu composite coating has certain cytotoxicity,When the amount of Cu in the coating reaches 2.5%or above,the toxicity of the coating does not increase with the increase of copper content.In this paper,nano-TiO₂ coating with strong particle attachment,uniform distribution and high antibacterial performance has been successfully prepared on the fabrics,and the coating does not have biological toxicity.Subsequently,nano TiO₂ is modified to prepare TiO₂/Cu composite coating,which has excellent photocatalytic antibacterial performance.Compared with single photocatalytic sterilization or Cu ion sterilization,the composite of the two has a synergistic mechanism.