Photo-induced switchable TiO₂ thin films for biological applications

Titanium and its alloys are key materials for biomedical applications due to their unique combination of high biocompatibility and mechanical strength. The interface between implant and tissue can be improved by titanium oxide coatings. Titanium oxide thin films prepared by electron beam deposition with well-defined structure, phase composition, morphology and local surface chemistry have been used in a study of the correlation between physicochemical surface characteristics and their biocompatibility, which have been shown dependent on preparation method and deposition parameters. In this study, three independent measurement methods were used for the determination of surface groups and charge: X-ray photoelectron spectroscopy, electrokinetic and contact angle measurements. The behavior of the thin titanium oxide films exposed to fibroblast L929 cells was studied. The aim of this study was to functionalize the oxide surfaces by controlling their properties through either defects introduced using high-temperature annealing, UV-light and/or modifier atoms as well as by molecules adsorbed at the surface, in particular, the formation of hydroxide groups. It was found that UV-light drives a switchable biocompatible titanium oxide surface, changing the surface charge polarity which increases or decreases the wettability of the films and the growth of the cells on the film’s surface correspondingly.