A review of physiochemical and photocatalytic properties of metal oxides against Escherichia coli

The paper reviews metal oxides' physiochemical and photocatalytic mechanisms of toxicity against E. coli. Photocatalysis is a process that aims to efficiently convert solar-to-chemical energy. This technology is extensively used in the environmental and energy fields, water purification systems and hydrogen evolution. This paper surveys metal oxides' antibacterial properties with special attention to reactive oxygen species (ROS), lipid peroxidation as a main process governing photocatalytic activity against E. coli, and theoretical models aiming at predicting disinfection rates. Furthermore, the paper highlights ways to improve photocatalytic efficiency, such as increased amount of ROS, specific light spectrum and intensity, and particles' morphology. This work would be incomplete without attention to physiochemical toxicity mechanisms towards E. coii. These processes are primarily based on metal oxides' solubility, and depending upon solubility properties, the mechanism is driven either by physical (mechanical) or chemical (metal ions) interaction. Finally, potential challenges to overcome during ROS-bacteria interaction (like, gas and nanobubbles formation) are enumerated. The review aims to fill the gap between photocatalysis as a chemical reaction and photocatalysis as a disinfection process. It would be helpful for materials scientists to get acquainted with another application of semiconductors, and challenges/opportunities laying on the boundary between materials and biological sciences. (C) 2018 Published by Elsevier B.V.