Antibacterial Activity of Nano-Structured TiO2 Surfaces: a Preliminary in Vitro Study

We report on preliminary results of bactericidal activity of anostructured titanium dioxide surfaces, obtained via two different techniques on titanium substrate: anodic oxidation and sol-gel film deposition. Anodic oxidation was performed in phosphoric acid in galvanostatic mode: obtained films showed typical interferometric colours, depending on the final applied voltage, and were amorphous (up to 40 V). Sols were obtained by hydrolysis of titanium isopropoxide in acidic environment and deposited via cold spray: films showed anatase crystallographic structure, without any further thermal treatment and did not show any evident alteration of the morphology and substrate colour. An appropriate testing chamber was then designed to perform bactericidal tests, by controlling UVA irradiation: bactericidal activity was assessed on two different bacteria strains (S. aureus and E. coli) and demonstrated to be photo-induced. These preliminary results show the ability of nano-structured surfaces in photoactivated biocidal activity of titanium dioxide surfaces.