**3.2.3 Anti-bacterial materials**

Photocatalytic decomposition reactions can be applied to the destruction of bacteria. Escherichia coli (*E. Coli*) cells are completely destroyed in one week under 1 mW/cm2 UV irradiation on TiO2 (Evans & Sheel, 2007; Fu et al., 2005; Liu et al., 2008; Sunada et al., 1998). Usually, an analogous anti-bacteria effect can be achieved in nearly 1 h under outdoor UV light intensity. However, the typical indoor UV light intensity is in the order of mW/cm2, thus the photocatalytic disinfection under indoor conditions require too long time to be considered useful from the practical point of view. The antibacterial function of TiO2 is strongly enhanced, even with weak UV intensity, using a fluorescent lamp assisted by the presence of Ag or Cu (Sunada et al., 2003). TiO2 photoactivity reaction assists the intrusion of the copper ions into the cell, which is probably the cause of the destruction of the *E. Coli* colonies even under very weak UV light.

Actually several nanostructured TiO2 derivatives are studied and applied as germicidal species, especially on the treatment of water contaminated with pathogenic microorganisms presenting a potential hazard to animals and human beings (Mccullagh et al., 2007; Skorb et al., 2008).
