In situ modification of cell-culture scaffolds by photocatalysis of visible-light-responsive TiO₂ film

We propose a novel process to modify the cell affinity of scaffolds in a cell-culture environment using the photocatalytic activity of visible-light (VL)-responsive TiO₂. The proposed process is the improved version of our previous demonstration in which ultraviolet (UV)-responsive TiO₂ was utilized. In that demonstration, we showed that cell-repellent molecules on TiO₂ were decomposed and replaced with cell-permissive molecules upon UV exposure in the medium where cells are being cultured. However, UV irradiation involves taking the risk of inducing damage to the cells. In this work, a TiO₂ film was sputter-deposited on a quartz coverslip at 640 °C without O₂ gas injection to create a rutile structure containing oxygen defects, which is known to exhibit photocatalytic activity upon VL exposure. We show that the cell adhesion site and migration area can be controlled with the photocatalytic activity of the VL-responsive TiO₂ film, while the cellular oxidative stress is reduced markedly by the substitution of VL for UV.