Unveiling the bacterial photoinactivation through cerium-gallium titanate nanotubes

Ion exchange may improve the surface and optical properties of titanate nanotubes, impacting their antibacterial performance. This work presents a characterization and antibacterial evaluation of titanate nanotubes exchanged with cerium and/or gallium. Analyzes of the chemical composition of the samples show that the ion exchange was satisfactory. Transmission electron microscopy images illustrate the preserved tubular morphology, and Brunauer-Emmet-Teller analysis indicates a considerable increase in surface area. The increased textural properties could be due to the presence of voids between adjacent particles of oxides and/or hydroxides of cerium or gallium deposited on the titanates. The band gap of nanotubes with cerium (2.87 eV) or cerium/gallium (2.88 eV) allows their excitation under light. Direct contact assays found that the cerium/gallium nanotubes increased inhibitory effects of S. aureus (83.1 +/- 23.9 a/o) and E. coli (70.3 +/- 20.6 a/o) under light. Hydroxyl radicals may be mainly responsible for the photoinactivation of bacteria. The increase in the surface area of the nanotubes, the effects of the interaction of cerium and gallium with bacteria, and the generation of reactive oxygen species under light explain the results obtained. Therefore, these nanotubes are promising in photoinduced reactions.