Phosphate-dependent modulation of antibacterial strategy: a redox state-controlled toxicity of cerium oxide nanoparticles

Bulletin of Materials Science

关键词: Redox active nanomaterials;    cerium oxide nanoparticles;    antibacterial;    superoxide dismutase;    catalase.;   

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

Specific reactivity of cerium oxide nanoparticles with phosphate ions was used to design a novel antibacterialsystem. The redox sensitivity of cerium oxide nanoparticles (CeNPs) was used to irreversibly scavenge phosphate ions fromthe microbial growth media resulting in nutrient starvation in microbes. Cerium oxide nanoparticles surface was engineeredwith different ratios of (Ce ($+$3)/Ce ($+$4)) cerium oxidation states and the effect of surface oxidation states was evaluatedon the antibacterial activity. The nutrient depletion-based antibacterial activity is demonstrated selectively by CeNPs withhigher Ce ($+$3)/Ce ($+$4) ratio on the surface. The surface chemistry of Ce ($+$3) is altered in the presence of phosphate,resulting in the irreversible formation of surface cerium phosphates leading to the loss of its intrinsic superoxide dismutase(SOD) activity. It is hypothesized that nutrient starvation by Ce ($+$3) leads to oxidative stress in microbes which is notneutralized by the altered surface chemistry of CeNPs with high (Ce ($+$3)/Ce ($+$4)) ratio. On the contrary, CeNPs withhigher (Ce ($+$4)/Ce ($+$3)) ratio did not show any reactivity towards phosphate, thus depicted no antibacterial activity,confirming the hypothesis that surface chemistry, rather than size or morphology-dependent toxicity is the main reason forthe observed antibacterial activity of CeNPs.

【 授权许可】

CC BY