In situ electrochemical study of the interaction of cells with thermally treated titanium

Micromotion and fretting wear between bone and Ti-based alloys in stem and dental implants breaks the passive film and exposes the metal to the action of the complex surrounding medium, generating substantial amounts of debris and continuous Ti ion release. In this work, oxidation treatments at low temperatures (277 °C, 5 h) have been used to promote the formation of wear-corrosion resistant titanium oxide on the Ti surface. The objective of this paper has been the study of the influence of live cells on the protectiveness of the oxide formed at these low temperatures. The interaction of cells with the modified surface has been studied by scanning electron microscopy, electrochemical impedance spectroscopy, polarization curves, and x-ray photoelectron spectroscopy (XPS). The chemical composition of the thermally treated Ti surface is mainly TiO2 as anatase-rich titanium dioxide with a low concentration of hydroxyl groups and a low mean nanoroughness that could promote good cell adhesion. The electrochemical results indicate that the cells alter the overall resistance of the thermally treated Ti surfaces by decreasing the oxide resistance with time. At the same time, the anodic current increases, which is associated with cathodic control, and is probably due to the difficulty of access of oxygen to the Ti substrate. XPS reveals the presence of proteins on the surface of the treated specimens in contact with the cells and a decrease in the Ti signal associated with the extracellular matrix on the surface and the reduction of the oxide thickness.The authors are grateful for financial support under Project Nos. MAT 2008-06719-C03-01, CTQ2008-05775/BQU, and MAT 2011-29152-C02-01 and from the Comunidad Autónoma de Madrid (CAM) through AVANSENS S2009/PPQ-1642.Peer reviewe