One-pot hydrothermal synthesis of Nb-doped TiO2 transition layer with exposed high-energy facets on TiNb alloy and its excellent apatite-forming inductivity

Titanium and its alloys, featuring superior comprehensive mechanical properties and biocompatibility, are ideal biomaterials for bone replacement and repair. However, their poor osteogenic biological activity lowers their clinical effectiveness to a certain extent. Thus, it is of great significance to build a highly active interface on the Ti-based substrate to accelerate the formation of biochemical binding between the implants and the human bone tissues. In this paper, we put forward a facile one -pot hydrothermal strategy to modify TiNb alloy in the H2O2- NH4F reaction system. The results show that a uniform Nb-doped anatase TiO2 transition layer, adhering well to the TiNb substrate, was successfully constructed. In addition, the film exhibited a hierarchical micro/nano structure, comprising truncated octahedral nanocrystals exposing {001} high-energy facets. After 21 days of immersion in simulated body fluid (SBF), a dense and thick hydroxyapatite coating was induced to deposit on this novel TiNb-based TiO2 film, demonstrating its excellent in vitro bioactivity. Our study puts forward new thoughts for the design of interfaces with enhanced bioactivity for biomedical implant, and also broadens the applications of TiO2 exposed {001} high-energy facets.