Engineered Metal Oxide Nanocrystallites: Antibacterial Activity and Stress Mechanism
Nanoparticles are being developed for several research as well as medicinal and engineering implications. Following them a host of new potential health issues due to their size-dependent larger surface area and high reactivity. In this brief chapter, an introduction on the likely interactions of nanoparticles with biotic environment, various possibilities of these man-made nanoparticles coming in contact with the environment and thereby consequences will be discussed. This will be illustrated using our recent work on the effects of various sizes of engineered cerium oxide nanoparticles on the growth and viability of several Gram-negative and Gram-positive microorganisms. The relation between the growth inhibition, reactive oxygen species (ROS) generation, and up- and/or downregulation of transcriptional stress genome using E. coli will be discussed. How different cerium oxide nanocrystallites were synthesized by solvent-free hydrothermal-based approach so as to eliminate cross contamination from the use of toxic solvents and surfactants. Further, utilization of advanced technique like the transmission electron microscopy and microarray-based transcriptional profiling to evaluate the bacterial response mechanisms will be described.