Cell responses on a H2Ti3O7 nanowire film

Abstract

Alkali treatment has been widely used for the surface modification of Ti and Ti alloys for clinical applications. However, the mechanism underlying the effects of the alkali-treated Ti surface on the cell response still needs to be explored. In this study, we demonstrated that the cell responses on a H₂Ti₃O₇ nanowire film, normally titanate generated on a Ti surface via alkali treatment and ion exchange, were sensitive to the surface hydroxyl groups of the H₂Ti₃O₇ nanowire films, i.e. the total amount as well as comparative ratio of the distinct type of surface hydroxyl groups (bridging-OH and terminal-OH). The surface hydroxyl groups of H₂Ti₃O₇ nanowires were further controlled via heat treatment to produce anatase TiO₂ nanowire films. Although there was no difference in both topographies, cells on a H₂Ti₃O₇ nanowire film showed more elongated shape than those on an anatase nanowire film. Moreover, the expression of ALP of cells on H₂Ti₃O₇ upregulated as compared to that on the anatase nanowire film at day 4, suggesting enhanced osteogenic capacity at an early stage. These results could be attributed to the difference in the distinct ratio of the terminal hydroxyl groups to the bridging hydroxyl groups, which was 0.42 for the H₂Ti₃O₇ nanowire film and 0.75 for the anatase nanowire film. It appeared that the bridging hydroxyl groups on H₂Ti₃O₇ were efficient in attracting Ca²⁺, which influenced the cell morphology and further upregulated the early differentiation.