Antibacterial effects of photocatalytic textiles for footwear application

In sportswear industry, body odors generated, in particular, in shoes are a big issue that remains unsolved because of the difficulties to destroy odors and bacteria at the same time. The effects of TiO2 coated textiles for footwear application on bacteria degradation have been assessed in darkness and under UV-A (λ > 340 nm) irradiation, using Staphylococcus epidermidis as model microorganism of skin bacteria. TiO2 treated polyester textiles were impregnated by padding process using TiO2 Degussa P-25 suspensions. The antibacterial effects of these textiles were evaluated using ISO 20743 standard with the transfer method and quantified by the plate count method. This standard has been adapted for photocatalytic tests on bacteria, adding an irradiation step to the ISO 20743 experimental procedure and new equations. In this study, different irradiances, exposure times, and titania contents were compared to find optimal performances on bacteria degradation. A total innocuity on skin bacteria of TiO2 coated textile was found in the dark. By contrast, under UV-A irradiation, even at very low irradiance (0.13 mW/cm2) of 20 min of UV exposure allows to completely inactivate S. epidermidis cells and avoid their regrowth with the 5.7 g/m2 TiO2-coated polyester surface. After 1 h of UV exposure, whatever the amount of TiO2 used (1-6 g/m2), all treated textiles were bactericidal.