Modification of the Ti15Mo alloy surface through TiO₂ nanotube growth—an in vitro study

Abstract

In this study, ordered and uniform TiO₂ nanotubular structures were obtained on the surface of the Ti15Mo alloy by anodic oxidation. The amorphous state of TiO₂ nanotubes formed under different anodization conditions was investigated. Crystallization of TiO₂ into anatase phase occurs during annealing at temperatures of around 400°C, whereas anatase to rutile transformation starts around 500°C and is completed at 800°C. Phase transformations in annealed samples led to morphological changes of tubular nanostructures, suggesting that the oxide layer formed at the nanotube/substrate interface serves as nucleation sites for more stable phases of TiO₂. The proliferation of fibroblasts cells under annealing conditions of 450°C, and of untreated samples (control group), was evaluated after 1, 4, and 7 days in cell culture using fluorescence microscopy images. A gradual increase in the number and size of cells was observed, indicating a non-toxic alloy. There was also better surface coverage on anodized samples compared with the untreated group; as well as increased development of the cytoskeleton in samples after anodization. The results of this study showed that the growth of TiO₂ nanotubular structures associated with annealing allow better cell adhesion on the Ti15Mo alloy surface.