REDOX STATE DEPENDENT TUNING OF ANTIBACTERIAL ACTIVITY OF CERIUM OXIDE NANOPARTICLE

Abstract

Cerium oxide nanoparticles have been used to scavenge reactive oxygen and nitrogen species. Cerium oxide poses the biological catalytic antioxidants property both as superoxide dismutase and catalase mimetic due to rapid change in their oxidative state between +3 and +4. CeNPs (3+) and CeNPs (4+) both exhibit superoxide dismutase and catalase mimetic activity, respectively. CeNPs will interact with components of biologically relevant buffers and medium, which could affect their SOD activity and catalytic properties. The + 3 state of CeNPs highly interaction with phosphate ions and thus loses its SOD activity. The exposure of phosphate anions to CeNPs (4+) did not persuade any significant change in its surface chemistry and therefore there is no much deviation in catalase mimetic activity. Exposure of phosphate anions to CeNPs (4+) did not block its redox cycling between 3+ and 4+ which was seen in +3 oxidative states. Binding of phosphate anions to cerium oxide nanoparticle (+3) can significantly distort the characteristics feature of CeNPs nanomaterials and thus shift their catalytic behavior because of it. Due to availability of phosphate ions in abundant quantity in biological systems in an inorganic form, it is possible that the action of CeNPs as a catalyst can strongly influenced by the local concentration of the phosphate ion in the cells in which it has been introduced. Due to the abundance of phosphate anions in the biological environment; it is likely that internalized CeNPs will be greatly influenced by cytoplasmic and nucleoplasmic concentration of phosphate. Here in this study we will target the antibacterial activity of Cerium oxide nanoparticle by reducing the phosphate environment in growth media. The toxic effect need to be demonstrated of interaction of cerium nanoparticle with phosphate at different concentration which will result in decline of the growth rate of bacteria in media.