Rafał Sadowski has got his PhD degree. Congratulation!

Photocatalytic coatings for medicine and food industry

The main goal of the doctoral thesis was to obtain stable and photoactive upon visible light irradiation semiconductor coatings on various polymers. A further purpose of this study was to understand the nature of semiconductor particles binding to polymer surface and determination of physical and chemical properties of the photocatalytic coatings. Additionally, the most active coatings were subjected to microbiological tests based on a modified ISO standard. The goal has been achieved by three steps procedure: activation, immobilization and sensitization. The crucial step was activation of the polymer surface by a low temperature oxygen plasma. It was shown that plasma pre-treatment is essential for oxygen groups formation which contribute to titanium dioxide binding to the polymer surface. Unmodified TiO₂ can only be used as a photocatalyst active under ultraviolet (UV) light, which limits future applications. For this reason coatings were photosensitized by titanium(IV) surface charge transfer complexes formed by impregnation with organic ligands (catechol, 2,3-napthalenediol, pyrogallol, salicylic acid, ascorbic acid and rutin). Moreover, the efficacy of such coatings against Escherichia coli and Staphylococcus aureus was demonstrated.