Photocatalytic disinfection of S. aureus using black TiO2−x under visible light

Abstract

Bacteria, alongside many other microbial pathogens, have long been a threat to human health, and the evolution of antibiotic resistant bacteria presents a significant public health crisis. Effective and persistent disinfection and sterilization techniques are required to prevent the spread of pathogenic microorganisms. Photocatalytic materials that are not depleted on activation can meet these criteria and thereby be suitable for the disinfection of air, water and surfaces. This study reports on photocatalytic black TiO_2−x (b-TiO_2−x) with disinfecting abilities when activated by visible light. The photocatalytic black TiO_2−x material was produced through a sol–gel combustion process. Characterization of the material demonstrated increased light harvesting capabilities when compared to commercially available anatase and rutile TiO₂, with evidence of an amorphous/anatase structure and high surface area (343 m² g⁻¹). The synthesized b-TiO_2−x proved capable of breaking down the organic dye methylene blue in only visible light, removing ∼78% of the dye in 210 minutes and ∼98% over the course of 24 hours. The b-TiO_2−x also proved capable of completely sterilizing a ∼1.5 × 10³ CFU mL⁻¹ solution of Staphylococcus aureus (ATCC25923), suspended in phosphate buffered saline (PBS), under visible light activation, demonstrating the potential for TiO_2−x substances as antibacterial materials.