Thin Photocatalytic TiO 2 Coatings: Impact on Bioadhesion and Cell Viability

On stainless steel, TiO 2 films allowed us to modify its hydrophilic character with a UV stimuli. After a UV irradiation time of 20 min, the water contact angle on both films (250 and 500 nm) decreased from 100° to 5° and remains stable up to 2 h after stopping the UV exposure. As a consequence, TiO 2 induces a significant decrease in the bacterial adhesion level. Moreover, this coating leads to smaller clusters of adhering cells (less than 10 bacteria per cluster instead of over than 1 000 bacteria per cluster on bare steel). Both TiO 2 coatings were also photocatalytic with an efficiency proportional to the thickness. It leads to antibacterial effect on adhering cells. TiO 2 layers induce a significant decrease in the viability of adhering cells in comparison with the bare steel; it decreases from 80 to 20%.