In-situ Hydrothermal Synthesis And In Vitro Biocompatibility Of TiO₂ Nanowires

TiO₂nanowires are one type of the representative inorganic materials and have been widely applied in the industrial and biomedical fields because of their ultra-high specific surface area,strong catalytic property,and good biocompatibility.They are conventionally synthesized via a substrate-assistant hydrothermal route due to simple operation and easy structural regulation.However,the weak interaction between TiO₂ nanowires and the supportive substrates such as FTO glass and Ti metals easily cause the detachment of TiO₂ nanowires from those substrates.Thus,it is very difficult to control the morphology and structure of the TiO₂nanowires for subsequent applications.To overcome this problem,in this thesis,TiO₂nanoparticle compacts are employed as potential substrate for synthesis of TiO₂ nanowires.Microstructure and in vitro biocompatibility of the as-synthesized TiO₂ nanowires are investigated.This thesis includes the following three parts.(1)Hydrothermal conversion of TiO₂ nanoparticles to TiO₂ nanowiresTiO₂ nanoparticles were synthesized through hydrolysis and condensation of isopropyl titanate as raw material via a sol-gel route and then hydrothermally converted to TiO₂ nanowires in a concentrated Na OH solution.The as-synthesized TiO₂ nanowires were characterized with SEM,EDS,TEM,XRD,and FT-IR.The results show that TiO₂ nanoparticles had an irregular shape with a diameter of 50-200 nm and showed amorphous structure.After hydrothermal treatment,TiO₂ nanoparticles were in situ converted to anatase-type TiO₂ nanowires with a diameter of 10±4 nm.(2)TiO₂ nanoparticle compacts as substrate for growth of TiO₂ nanowire membranesTiO₂ nanoparticle compacts were prepared by compressing the TiO₂ nanoparticles in a cylindrical stainless-steel mold and then used as supportive substrate for synthesis of TiO₂nanowire membranes.The as-prepared TiO₂ nanowire membranes were characterized by SEM,EDS and XRD.The results show that TiO₂ nanowire membranes were grown on the surface of TiO₂ nanoparticle compacts.It finds that the hydrothermal temperature has a significant effect on size and morphology of TiO₂ nanoparticle compacts.By increasing the temperature from120?to 200?,TiO₂nanoparticles on the compacts were gradually converted to nanowires with the diameter ranging from 10 nm to 1?m.During hydrothermal process,anatase phase TiO₂ nanoparticles gradually converted to titanic acid nanowires.(3)Biological evaluation of TiO₂ nanowire membranesL929 fibroblast cells were used to evaluate the biocompatibility of the as-synthesized TiO₂nanowires membranes.The compacts without and with TiO₂ nanowire membranes were separately co-cultured with cells.The cell viability was quantitatively analyzed via a MTT assay and qualified with a live/dead assay.Cell morphology was observed under a SEM machine.The results show that the as-synthesized TiO₂ nanowire membranes well supported the attachment and proliferation of cells,indicating a good biocompatibility.It finds that the cell viability was correlated with the diameter of the nanowires.The nanowires with small diameter promoted the cell attachment and proliferation.