Microstructure and phase transition of biocompatible titanium oxide film on titanium by plasma discharging

This study investigated the feasibility of using oxygen plasma discharging on titanium for forming a biocompatible layer between the bone plate and bone tissue. Plasma discharging formed a nanostructural oxidation layer on the titanium bone plate. The nanostructural oxidation layer revealed oxygen and titanium bonding states following oxygen plasma discharging. A (α → (α + TiO) → (α + TiO + γ-TiO₂)) phase transition was observed within the titanium matrix during plasma discharging. This result has never been previously reported. The plasma oxidation with argon pretreatment not only produces titanium oxide layer, but also results in formation of nanostructural titanium oxide phase. Nano-rutile-TiO₂ (γ-TiO₂) can be enhanced osseointegration of implant such as orthopedic and dental implants. In addition, nano-(TiO + γ-TiO₂) phases were formed on the nanostructural oxidation layer by plasma discharging. Formation of a nanostructural rutile-TiO₂ on oxidation layer is related with the cell and blood reaction and distribution selectivity, then promoting hemocompatibility and protein binding as well as osseointergration. Therefore, surface oxidation by plasma discharging is thus believed to improve the biocompatibility and tissue healing. Furthermore, plasma discharging not only enhances phase transformation on titanium surface, but also generates a nanostructural oxide layer, improving the bioactivity and hemocompatibility of bone plate.