The Research On Modification Of TiO₂ Nanotube Arrays On Titanium Implant And Their Properties

TiO₂ nanotube arrays have received extensive attention in the field of biomedical materials,owing to their large specific surface area,controllable morphology and excellent biocompatibility.In this thesis,to improve the bioactivity and antibacterial activity of TiO₂ nanotube arrays fabricated by anodic oxidation,surface-modified nanotube arrays were prepared by alkaline-heat treatment,enriching calcium ions,coating silica mesoporous films and loading silver nanoparticles.The growth of apatite on specimens was examined by immersion tests in a modified simulated body fluid?m-SBF?.The mechanism of apatite growth was investigated.The human osteosarcoma cells?MG-63?were cultured on the surface-modified nanotube arrays to determine the cytocompatibility in vitro.?1?The titania nanotube arrays were fabricated by anodization of titanium foils in 0.5 wt%aqueous hydrofluoric acid and 10 g/L disodium hydrogen phosphate electrolyte.The influence of preparation conditions on the morphology and microstructure were studied,including oxidation time,counter electrode and heat treatment temperature.The results reveal that the anodization was carried out at 20 V for 40 min using a Ti foil as the anode and a graphite paper as counter electrode,and then annealed at 500?,highly ordered and oriented nanotube arrays were prepared?TiO₂ NTs?.The nanotubes were alkaline-heat treated?TiO₂ NTs-1?.After soaking for14 days in m-SBF,the hydroxyapatite?HA?was formed on TiO₂ NTs,owing to electrostatic interactions between HPO₄^2-adsorbed in the wall of nanotubes and ions in m-SBF.The sodium titanate layer on TiO₂ NTs-1 promoted the apatite formation.The human osteosarcoma cells?MG-63?were cultured on the nanotubes mentioned above,indicating good cytocompatibility in vitro.The Alamar Blue activity of MG-63proliferation on TiO₂ NTs-1 was superior to that of TiO₂ NTs after 7 days of incubation.?2?Three kinds of calcium-ion-containing solutions were prepared,including calcium nitrate,calcium chloride and calcium hydroxide.Calcium ions enriched nanotube arrays were fabricated using ultrasound aided impregnation on TiO₂ NTs substrate.The influence of calcium source,impregnation time and impregnation process on the morphology and microstructure were discussed.The results show that calcium source and impregnation time has a negligible effect on the morphology of the nanotubes.Nevertheless,for calcium ions enriched nanotubes using ultrasonic aided impregnation,the mouth of nanotubes become glossy,high amount of calcium ions adsorbed in the wall of nanotubes,in comparison to conventional impregnation.The calcium ions modified nanotubes clearly enhanced the formation of HA compared with the unmodified nanotubes after soaking for 7 days in m-SBF,which may attribute to the release of calcium ions and significantly high amount of Ti-OH groups on its surface;in addition,calcium ions enriched nanotubes are suitable for MG-63 growth,indicating good cytocompatibility in vitro.?3?The cubic mesoporous silica films were synthesized on Ti substrate by evaporation-induced self-assembly method.The solvent extraction and calcination used as template removal were contrasted.The solvent extraction can not only remove the template thoroughly but also prepare cubic mesoporous films.Under the above conditions,the homogeneous and compact mesoporous silica-titania nanotube composite films were prepared by dip-coating for three times in a silica sol after aging for 48 hours on TiO₂ NTs substrate.A thin carbonate hydroxyapatite layer was covered on the surface of mesoporous films after soaking for 14 days in m-SBF,which may attribute to the unique mesostructure and the presence of abundant Si-OH groups.Hydroxyl groups are efficient inducers for HA formation on the composite films surface.The composite films can promote the MG-63 cell adhesion and proliferation,owing to hydrophilic surface.?4?Silver nanoparticles loaded nanotube arrays were fabricated on TiO₂ NTs substrate via ultrasound assisted impregnation and photochemical synthesis method.The preparation conditions were optimized by orthogonal experiments,including the concentration of silver nitrate solution,impregnation time and impregnation process.The results show that the optimized Ag nanoparticles loading and size distribution was obtained in 1.0 mol/L Ag NO₃ solution using ultrasonic assisted impregnation for 10min.Silver nanoparticles loading can not only induce HA formation in m-SBF but also promote the strong adsorption in visible light region.The antibacterial ratio reached up to 90%using Staphylococcus aureus as strain,which was due to synergistic effect between silver nanoparticles and TiO₂ nanotube arrays.