Surface modification of TiNb alloy through hydrothermal treatment and its in vitro bioactivity

Surface modification of biomedical titanium and its alloys was considered as an effective method to improve their bioactivity and accelerate the integration between implanted materials and the human tissue. For this purpose, we described the fabrication of TiO2 thin film on the surface of TiNb, one kind of titanium alloy with good biocompatibility, by a facile hydrothermal treatment in H2O2 solution in this study. Field-emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), x-ray photoelectron scanning (XPS), Energy dispersive x-ray spectroscopy (EDS) and water contact angle measurement were used to characterize the morphology, crystal phase, chemical compositions and surface character of the samples. The results show that irregular micro-sized islandlike structure, assembled by many nanocrystals with a size of 20 similar to 40 nm, was formed on the surface of TiNb alloy after hydrothermal treatment. Moreover, the crystal phase of the as-fabricated film was determined as Nb-doping anatase TiO2. Meanwhile, in vitro bioactivity of the micro/nano-textured TiNb-based TiO2 film was evaluated by simulated body fluid (SBF) immersion test. The result demonstrated that TiNb alloy after surface modification exhibited excellent apatite-forming ability. After immersion in SBF for 18 days, a dense spherical hydroxyapatite layer was formed on the surface of TiNb alloy. Its outstanding bioactivity could be attributed to the good super-hydrophilicity, micro/nano microstructure and abundant hydroxyl group of the TiO2 film obtained by hydrothermal treatment of TiNb alloy.