Photon-driven bactericidal performance of surface-modified TiO2 nanofibers

Abstract

Visible-light-responsive graphite-embedded titanium dioxide nanofibers (G-TiO₂ NFs), prepared by electrospinning and post-treatment with rhodizonic acid (RhA), show biocidal effects against E. coli and S. aureus when excited with visible light. The red absorption shift of surface-modified G-TiO₂ NFs with RhA of about 1.1 eV is a consequence of interfacial charge transfer (ICT) complex formation facilitated by a condensation reaction between hydroxyl groups originating from the ligand and surface TiO₂. The optical properties of the inorganic–organic hybrid are studied in-depth by density functional theory (DFT) calculations using a cluster model. The prepared samples are thoroughly characterized using X-ray diffraction (XRD) analysis, electron paramagnetic resonance spectroscopy (EPR), Fourier-transform infra-red (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Under visible light illumination, surface-modified G-TiO₂ NFs display a near-to ideal biocidal effect against E. coli and S. aureus and no cytotoxicity was observed toward L929 fibroblast cells. Overall, the experimental results suggest that fabrics based on surface-modified G-TiO₂ NFs with RhA can be potentially used to control the persistence and spread of bacterial infection.