Self-cleaning application of mesoporous ZnO, TiO₂ and Fe₂O₃ films with the accommodation of silver nanoparticles for antibacterial activity

Background: The infections spread in healthcare circumstances is a growing and persistent issue worldwide, motivated by the development of microbial durability to disinfectants and antibiotics. Self-cleaning or disinfecting is one of the most attractive and promising technologies for glass windows, buildings, operating rooms, and hospitals. Method: The transparent films of mesoporous TiO₂, ZnO and Fe₂O₃ with different layers were synthesized and coated with silver nanoparticles through the sol-gel technique. The contact angles of the Ag/ZnO, Ag/TiO₂ or Ag/Fe₂O₃ films were found to be less than 10°, indicating the obtained films were superhydrophilic. These films were tested for their disinfection ability for different bacteria species under direct light illumination. Significant Findings: Results have shown that Ag/TiO₂ exhibited strong anti-bactericidal performances, and the Ag/TiO₂ 1-layer (1L), 2-layer (2L) and 3-layer (3L) films were the best of all treatments producing consistently higher antibacterial activity with Vibrio parahaemolyticus, Aeromonas hydrophila, and Bacillus subtilis in the reducing order of efficacy. The exposure time of 3 h was sufficient to reduce the cell counts of bacterial strains. The reason behind the higher antibacterial activity of Ag/TiO₂, Ag/ZnO and Ag/Fe₂O₃ films compared with pristine ZnO, Fe₂O₃ and TiO₂ films might be the surface plasmon resonance of Ag nanoparticles. The small Ag clusters create sinks for electrons, thus expediting the photoinduced electron- holes separation and enhancing the antibacterial activity. Therefore, the highest antibacterial activity observed for the Ag/TiO₂ films was referred to as the most effective separation of charge carriers during the fast charge transfer.