Dopamine Assisted Preparation Of Ag-doped TiO₂ Nanomaterials And The Study Of Its Antibacterial Properties

The infection of microorganisms such as bacteria and fungi seriously threatens human health.The preparation and application of the antibacterial materials are of great significance in solving the problem of bacterial infection.At present,there are many antibacterial materials on the market,and the inorganic antibacterial materials are most widely used because of their good bactericidal effect,long-lasting safety,and good heat resistance.Among them,anatase TiO2 and Ag nanoparticles are the most widely used materials.At present,there are many methods for preparing Ag-doped TiO2 nanoparticles,but most of them need some special equipment or have special requirements for materials.In this work,dopamine(DA)was used as a surface modifier which have a structure similar to the adhesive proteins.Based on the self-polymerization-adhesion behavior and its reduction of metal ions of dopamine,Ag-doped TiO2 nanoparticles were successfully prepared using ashless quantitative filter paper and soda-lime glass as templates.This paper provides a preparation method of Ag-doped TiO2 nanoparticles,and provides a novel idea for the preparation of metal-based antibacterial materials.(1)Preparation of Ag-doped TiO2 by filter paper template methodBased on self-polymerization and reducibility of polydopamine(PDA)Membrane.In this thesis,TiO2 thin films with filter paper morphology were prepared by sol-gel method using filter paper as template.Ag-doped TiO2 nanoparticles were obtained by reduction Ag+ and immobilization it on the surface of TiO2 by PDA.The prepared materials were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM).transmission electron microscopy(TEM),ultraviolet-visible diffuse reflectance spectroscopy(UV-vis DRS),and X-ray photoelectron spectroscopy(XPS).The results showed that the crystal structure of TiO2 nanoparticles was anatase and Ag is in the state of Ag0.The band gap of TiO2 can be effectively reduced by doping of PDA and Ag.There is a strong interaction between Ag and TiO2.E.coli was used as a test bacterium to evaluation the antibacterial properties.The antibacterial effect were studied by using plate coating method.The results indicated that Ag-doped TiO2 has excellent antibacterial effect under visible light,and its antibacterial effect gradually increases with the increase of Ag content.(2)Preparation of Ag-doped TiO2 by Soda-lime glass template methodPDA contains a large amount of catechol and amino groups,which can be used as a secondary reaction platform to achieve surface functionalization of solid materials.Based on this property of PDA,a layer of PDA film was first covered on the surface of the soda-lime glass.After that,it was soaked in a TiO2 sol which containing AgNO3.A modified glass containing Ag-doped TiO2 nanoparticles on the surface was obtained by dipping method.The prepared materials were characterized by water contact angle,UV-visible,SEM,XPS and XRD.The results indicated that the hydrophilicity of Ag doped TiO2 glass is enhanced compared with bare glass;the ability of absorption of visible light of TiO2 is enhanced due to the presence of PDA and Ag.The results indicated that Ag exists in the state of Ag0.There is a strong reaction force between TiO2 and Ag.The results of ICP analysis showed that Ag content of the modified glass surface is about 2.4 ?g/cm2.After 8 days of immersion in water,the maximum Ag overflow rate is about 5.2×10-3 ?g/cm2,which is only 0.2%of the total content.The antibacterial properties of the prepared materials were tested by plate coating method and CLSM by using E.coli.The results showed that Ag-doped TiO2 had an excellent antibacterial persistence,antibacterial efficiency can still reach 99%even immersed in phosphate buffered saline(PBS)solution after 60 days.