Light-induced bioactive TiO2 surface

We have achieved bioactivity enhancement of nanostructured titania using ultraviolet (uv) light irradiation. The titania coating fabricated by nanoparticle plasma spraying consists of a nano-TiO2 coating surface composed of primarily nanosized anatase. After irradiation by ultraviolet light in air for 24 h, the as-sprayed and UV-irradiated TiO2 coatings were soaked in simulated body fluids (SBF) to investigate their bioactivity. The UV-illuminated TiO2 coating induced bonelike apatite formation on the surface whereas no apatite could be detected on the as-sprayed TiO2 coating. The formation of oxygen vacancies at the two-coordinated bridging sites by UV illumination is believed to result in the conversion of the corresponding Ti4+ sites to Ti3+ sites, which are favorable to the dissociation of water in the SBF and subsequent formation of Ti-OH and an apatite layer. Our results reveal that the surface bioactivity of titania coatings can be induced by UV illumination.