Formation and Bioactivity of SrTiO3 Nanotubes on Titanium by Modified Anodization and Hydrothermal Treatment

Abstract

SrTiO 3 nanotube films with good adhesion strengths to Ti substrates were fabricated by using a hybrid approach with a modified anodization and a hydrothermal treatment (HT). The effect of Sr 2+ concentration in HT solutions on the morphologies and phase components of the nanotubes were investigated, the SrTiO 3 nanotubes formation mechanism was explored, and the adhesion strengths, hydrophilicity and apatite-forming ability of the SrTiO 3 nanotubes were also evaluated. The results demonstrated that with increasing the incorporation of Sr 2+ into the nanotubes, no obvious changes of the lengths and outer diameters of the nanotubes were observed, but the wall thickness and the crystallinity of SrTiO 3 in the nanotubes increased. The accumulation of Sr at the inner tube wall indicated that the reaction of Sr 2+ with TiO 2 mainly occurred in the vicinity of internal surfaces of the closely arranged nanotubes. The formation of the SrTiO 3 nanotubes could be attributed to an in situ dissolution–recrystallization process. The SrTiO 3 nanotubes exhibited good hydrophilicity and bioactivity, and the induced apatite preferred to nucleate on the nanotubes with higher crystallinity and Sr content, indicating a good bio-adaptability of the SrTiO 3 nanotubes for orthopedic application.