Microscopic observations of osteoblast growth on micro-arc oxidized β titanium

► Anatase-rich TiO2 and rutile-rich TiO2 coatings were successfully grown on β-Ti alloy. ► Rutile-rich TiO2 coatings achieved an enhanced in vitro biocompatibility. ► The osteoblast and TiO2 interaction is fully explored in this study. ► Osteoblast grows into MAO-TiO2 structure and no micro-gap found on rutile-rich TiO2. ► MAO can be a novel surface-modification method on β-Ti alloy for medical implants.