In vitro characterization and osteoblast responses to nanostructured photocatalytic TiO2 coated surfaces

The aims of the study were to characterize a nanostructured photoactive titanium dioxide (TiO2) coating and to compare the cellular response of human osteoblasts before and after ultraviolet (UV) irradiation of the coating. A specific nanostructured TiO2 powder (Degussa P-25), which consists of approximately 80% anatase and 20% rutile, was spin-coated onto commercially pure titanium discs, and was heat-treated thereafter. After topographical, chemical and photocatalytic property characterizations, human osteoblasts were cultured on the coated discs before and after UV irradiation. Cell morphology was evaluated by scanning electron microscopy (SEM), and cell viability was analysed by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. From the contact angle analysis, the wettability significantly improved after UV irradiation. The cultured cells were flattened with numerous elongated lammellipodia; however, no morphological differences were indicated between –UV and +UV surfaces. The MTT assay analysis showed that –UV surface presented significantly higher viability compared to the +UV surface except for one cell population group at 3 h where there were no differences. The nanostructured photoactive TiO2 surface improved its hydrophilicity by UV irradiation, however no enhancing effect in cell response was confirmed at the time tested compared to the non-irradiated surface.