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      https://www.ias.ac.in/article/fulltext/boms/037/03/0371-0381

    • Keywords

       

      Cytotoxicity; dark; FT–IR; FT–Raman; XPS; fluorescence spectroscopy.

    • Abstract

       

      The probable underlying mechanism(s) of bacterial cell–TiO2 nanoparticles (TiO2 NPs) interaction in the absence of photo-irradiation has been less studied since most of the prior cytotoxicity studies focused on irradiated TiO2. The present study draws attention to the possible role of cell surface–TiO2 NP interactions under dark conditions, through an array of spectroscopic and microscopic investigations. A dominant freshwater bacterial isolate, Bacillus licheniformis, which interacted with environmentally relevant concentrations of TiO2 NPs (1 𝜇g/mL), was analysed and compared under both light and dark conditions. Aggregation of cells upon NP interaction and adsorption of NPs onto the cell membrane was evident from the scanning electron micrographs under both light and dark conditions. The FT–IR and FT–Raman spectra suggested stress response of bacterial cells by elevated protein and polysaccharide content in the cell–NP interaction. The X-ray photoelectron spectroscopic data substantiated the reduction of titanium from Ti(IV) to Ti(III) species which might have contributed to the redox interactions on the cell surface under light as well as dark conditions. The internalization of NPs in the cytoplasm were obvious from the transmission electron micrographs. The consequent cell death/damage was confirmed through fluorescence spectroscopy and microscopy. To conclude, the current study established the substantial role of interfacial interactions in cytotoxicity of the TiO2 NPs irrespective of the irradiation conditions.

    • Author Affiliations

       

      Swayamprava Dalai1 Sunandan Pakrashi1 Sujay Chakravarty2 Shamima Hussain2 N Chandrasekaran1 Amitava Mukherjee1

      1. Centre for Nanobiotechnology, VIT University, Vellore 632 014, India
      2. UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603 104, India
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    • Supplementary Material

       
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