UV-irradiation-induced bioactivity on TiO2 coatings with nanostructural surface.

Titania (TiO2) coatings with nanostructural surface prepared using plasma spraying technology were irradiated by ultraviolet light in simulated body fluids to improve their bioactivity. The in vitro bioactivity of the coatings was evaluated by investigating the formation of apatite on their surfaces in simulated body fluids. Bone-like apatite was observed to precipitate on the UV-irradiated TiO2 coating with nanostructural surface after it was immersed in simulated body fluid for a certain period, but not on the as-sprayed and UV-irradiated TiO2 coatings without nanostructural surface. The results indicate that the nano-TiO2 surface can be activated by UV-irradiation to induce its bioactivity. The ability of apatite formation on the nano-TiO2 surface was improved with the increase of UV-irradiation time. The in vivo results reveal that the as-prepared TiO2 coating with nanostructural surface cannot induce the formation of new bones during the implantation period, but the UV-irradiated TiO2 coating with nanostructural surface could do so during an implantation time longer than 2 months. Our results indicate that the osseointegration ability of the plasma-sprayed TiO2 coating with nanostructural surface can be improved by UV irradiation.