Influence of a UVA-Activated TiO₂ Coating on Bacterial Surface Colonization in Water-Bearing Systems

This study focuses on the use of superhydrophilic titanium dioxide (TiO2) coatings applied to the surfaces of water-bearing systems to prevent surface colonization and biofilm formation. Biofilms in water-bearing systems are a problem in many industrial areas and are associated with risks to hygiene and health, material damage, and high costs for cleaning and maintenance. We investigated the suitability of TiO2 coatings activated by UVA irradiation to achieve a superhydrophilic surface. The well-adherent coatings were deposited on flat and curved substrates (stainless steel, Al2O3) by pulsed magnetron sputtering. Surface characteristics, wettability, and the influence on microbial surface colonization were evaluated by WCA measurements, SEM, and XRD. For microbiological evaluation, Escherichia coli and Staphylococcus warneri were used. An adapted and specialized regime for sample conditioning and testing was developed that allows comparability with upcoming studies in this field. The superhydrophilicity was stable for up to 4 days, and an additional UVA reactivation step revealed comparable results. The microbiological studies proved a successful prevention of bacterial colonization on the activated coatings, which is attributed to their superhydrophilicity. The results demonstrate the potential of UV-activated TiO2 as a long-term coating of water-bearing systems, like pipes, on which it assists in avoiding biofilm formation.