Preparation And Characterization Of TiO₂ Nanospheres Based On Substrate

As a new high-performance inorganic material,Nano-TiO₂ shows many unique physical and chemical properties.Such as excellent photocatalytic activity, photoelectric property,photo induced super-hydrophilicity,good biocompatibility and capability of inducing bone mineral deposition.In this thesis,based on the good biocompatibility of nano-TiO₂ coating and photo-induced super-hydrophilicity of the surface,free-standing TiO₂ nanospheres layers with photo switchable hydrophilicity and hydrophobicity were prepared and characterized.The possible biological application of such layers,as well as the effects of material intrinsic property and photo excitation,are explored and discussed.Firstly,TiO₂ nanoparticles are prepared on a Si wafer substrate through a combined method of sol gel processing and spinodal phase separation.Then,on Si wafer substrate,the structure and photo-induced hydrophilic-hydrophobic conversion performance of TiO₂ nanospheres are studied.Finally,on Ti substrate,the in vitro property of TiO₂ nanospheres and the impact of hydrophilicity and hydrophobicity are discussed.Means of characterization include X-ray diffraction,scanning electron microscopy,transmission electron microscopy,X photoelectron spectroscopy,Fourier transform infrared spectroscopy,contact angle measurement,simulated body fluid immersion,as well as in vitro cell culture,etc.The research results show as below:1.The compact layer with randomly distributed TiO₂ nanospheres is formed on the Si substrate.It has single-layer structure.And corresponding to the diameter of nanoparticle,the thickness of TiO₂ nanospheres is 50-100nm.When doping La ions, Fe ions,N ions respectively,they are able to successfully enter the spherical TiO₂, and the surfacing morphology of TiO₂ nanoparticles remains the same.2.TiO₂ nanospheres layer on Si wafer substrate has characteristics of hydrophilic-hydrophobic conversion with photo excitation.Such feature can be regulated by experimental conditions,ion concentration and ion doping to certain extent. 3.The compact layer with randomly distributed TiO₂ nanospheres is also formed on the Ti substrate successfully.Through simulated body fluid immersion and cell culture, TiO₂ nanospheres show excellent characteristics of apatite deposition and in vitro cell compatibility.Meanwhile,after UV irradiation,the biological activity of such surface layers improved due to enhanced hydrophilicity.