Water pollution is a serious problem in developing countries due to the presence of organic contaminants and biological species. To solve this issue, our group developed a series of photocatalysts. In this study, a feasible colloidal approach was used to prepare cerium cations (Ce4+) doped titania (TiO2) composites (CTCs), followed by functionalization using natural product extracts. These CTCs displayed synergistic efficacy to decompose toxic compounds and pathogenic bacteria. Different molar ratios of Ce to Ti were used to form forty formulations of CTCs with tunable structures and sizes. Characterization indicated highly crystalline anatase CTCs were obtained and crystallite sizes can be tuned. The electrokinetic potential reflected the potential difference between the stationary layer of fluid around the solubilized solute and the dispersion medium. The CTCs with smaller diameter exhibited a large negative zetapotential and long-term stability. These CTCs displayed photocatalytical reactivity to decompose the model organic containment (methylene blue) under visible light conditions. The CTCs also rapidly destroyed both Gram-negative (S. marcescens) and Gram-positive (M. luteus) bacteria in low parts per million concentration range. The mechanisms of microbe inactivation can be summarized and hypothesized as three modes: 1) Lipid peroxidationby direct and indirect interaction via reactive oxygen species; 2) Disruption of DNA replication and repair due to DNA conformational changes; and 3) Inhibition of respiratory proteins by promoting dimerization of the enzyme and leading to inhibition of respiration.

Feasible colloidal approach to produce nanostructured composites to inactivate pathogenic bacteria under visible light conditions

251st National Meeting (2016)

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