Fabrication of new TiO2-SnSe composites with enhanced antibacterial performance against E. coli and S. aureus

Abstract

In this work, TiO2, SnSe and their composites with different mass ratios of SnSe were fabricated by using cost-effective chemical route. The structural, optical, morphological, and antibacterial properties of the composites were systematically evaluated and compared with those of TiO2 and SnSe. Formation of anatase phase of TiO2 and orthorhombic structure of SnSe were confirmed through their respective X-ray diffraction (XRD) patterns. The results were supported by Raman analysis, which showed the characteristic vibrational modes of TiO2 and SnSe. For the TiO2-SnSe composites, broadening and a systematic shift towards higher wavenumbers was observed with the increase of SnSe concentration. Furthermore, a change in the surface morphology of TiO2-SnSe composites from agglomerated nanoparticles to plates-like nanostructures was observed for varying content of SnSe. Compared to pure TiO2, the TiO2-SnSe composites exhibited a significant shift in the spectral response towards visible region. A red-shift in the energy bandgap values from 3.25 eV (pure TiO2) to 2.42 eV (TiO2-75% SnSe) was observed. The antibacterial performance of TiO2, SnSe and their composites was evaluated against the Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains under visible light. Compared to TiO2 and SnSe, the composites revealed a superior antibacterial activity by exhibiting larger zones of inhibition. Furthermore, the minimum inhibitory concentration of TiO2-75% SnSe for S. aureus and E. coli was respectively determined to be 0.25 ± 0.01 and 1.50 ± 0.01 mg/mL, which was substantially lower than the TiO2. Moreover, TiO2-SnSe composites were found to be biocompatible, as more than 80% of RBCs remained viable.