Research On The Surface Modification Of TiO₂Nanotube Arrays And Its Bioactivity

Because of the good b iocompatib ility, tita nium has been widely used in hardtiss ue materia ls, such as artific ia l bones, joints, teeth and so on. However, tita niumwill be prone to rejectio n when imp lanted in human body due to its bio inertia. Thus,in order to improve the b ioactivity of tita nium, surface modification is ofte nperformed. In this work, TiO₂nanotubes array was obtained by anodization of highlypure tita nium in HF aqueous solut io n. Then acid and alkali solut ions were imp lied tomodify the surface of the as-sprayed TiO₂nanotubes array. The surface microstructuremorphology, composition and bioactivity of the samp les before and after mod ificatio nwere studied. In addition, TiO₂nanotubes/SiO₂mesoporous compos ite films wereprepared on the surface of the highly pure tita nium. The mesoporous structure of SiO₂mesoporous thin film and the bioactivity of the TiO₂nanotubes/SiO₂mesoporouscompos ite films were also examined. The research results o f this work are as fo llows:1. TiO₂nanotubes array was obtained by anodization of highly pure tita nium in0.5%HF aqueous so lutio n. The influence of the heat-treatment syste m on the surfacemicrostructure morphology and composition of TiO₂nanotubes array was discussed.Also, the apatite-forming ability o f the sa mples was exa mined by soaking the m in thesimulated body fluid （1.5SBF）. The results showed that the highly ordered TiO₂nanotubes array was fabricated by anodic oxidation. With the increace ofheat-treatment te mperature, the wall of TiO₂nanotubes array was thicker, whereas thepores were thinner. In addition, the compositio n of TiO₂nanotubes array was changedfro m amorphous to anatase and rutile. The compos ition of TiO₂nanotubes arraytreated under500°C was anatase and rutile, and here no HA was formed on thesurface of the TiO₂nanotubes array, which meaned a poor bioactivity.2. Acid and alka li solutions were imp lied on the surface modification o f theas-sprayed TiO₂nanotubes array. In addition, the apatite-forming ability of thesamples after modification was examined by soaking them in the simulated body fluid（1.5SBF）. The results s howed that, TiO₂na notubes array treated by2mo l/L HCl or3mo l/L NaOH was able to ma inta in the origina l appearance. And after soaking in1.5SBF for14days, the surface of the samp les treated above were covered byhydroxyapatite（HA）, whic h mea n a good apatite forming ability in vitro.3. TiO₂nanotubes array was obtained by anod ization o f titanium in0.5wt%HFaqueous solution and then heat treated under the temperature of500°C for2hours. After that, Ca2+ions were incorporated by a two-step pre-calc ification process. Theapatite-forming ability of the samp les after pre-calc ification was examined by soakingthem in the simulated body fluid （1.5SBF）. The results showed that the highly orderedTiO₂nanotubes array was fabricated by anodic oxidation. After soaking in SBF for14days, the s urface of the two-step pre-calc ified samp le was deposited byhydroxyapatite（HA）, whic h mea ns a good apatite forming ability in vitro.4. TiO₂nanotubes/SiO₂mesoporous composite film were prepared by sol-geland dip-coating methods. The apatite-forming ability of this composite film wasexamined by soaking it in the simulated body fluid （1.5SBF）. The results showed thatthe highly ordered TiO₂nanotube arrays were fabricated by anodic oxidation. Themesoporous silica thin film using sol-gel and dip-coating techno logy had a we llordered hexa gona l mesostructure. And the composite film had a good apatite formingability on its surface in vitro.