Ni- and Co-doped TiO2 nanofibers for enhanced antibacterial and antibiofilm activities, and mechanistic insights

Abstract

Nowadays, with the growing need for alternative antibacterial materials for the treatment of bacterial infections, TiO₂ with antibacterial properties has attracted attention as a potential antibacterial agent. Ni-TiO₂ and Co-TiO₂ nanofibers (NFs) were synthesized via an electrospinning process. The antibacterial activities of these NFs against S. aureus and E. coli were evaluated under UV-light illumination using optical density measurements. Co-TiO₂ exhibited superior antibacterial activity against both S. aureus and E. coli under UV-light irradiation. The antibacterial mechanism was further investigated through a glutathione (GSH) oxidation assay and morphological analysis using scanning electron microscopy (SEM). Hydrophilicity was evaluated by contact angle measurement. The antibiofilm activities of TiO₂, Ni-TiO₂, and Co-TiO₂ NFs were investigated with respect to E. coli and S. aureus biofilms. Ni-TiO₂ and Co-TiO₂ demonstrated more effective antibiofilm activities than bare TiO₂. Under UV-light irradiation, the biofilm inhibition efficacy was increased for both Ni-TiO₂ and Co-TiO₂ NFs while Co-TiO₂ NFs were found to have the greater antibiofilm performance. Additionally, in silico analysis was conducted to explore the molecular interactions of the NFs with S. aureus Immunoglobulin-Binding B Domain (PDB ID: 1BDD) and FimH lectin protein of E. coli (PDB ID: 4XO8). Co-TiO₂ exhibited stronger binding to S. aureus, while TiO₂ showed stronger binding to E. coli.