Inhibition of Nanoceria's Catalytic Activity due to Ce3+ Site-Specific Interaction with Phosphate Ions

Cerium oxide nanoparticles (CNPs) exhibit superoxide dismutase (SOD) and catalase mimetic activities. Therefore, based on its catalytic activities, CNPs can potentially be used to treat diseases associated with oxidative stress. The potency of CNPs can be hindered by ion interaction due to chemical modifications. The issue is that phosphate ions are relatively ubiquitous in all biological relevance medium and body fluid. Our ventures in this study were to understand the phosphate ion interaction and fabricate CNPs that are biocompatible and simultaneously retain their catalytic properties in the presence of phosphate ions. CNPs were coated with polyethylene glycol and dextran in order to enhance biocompatibility. A series of experiments determined that maximizing the preserved catalytic responses were highly dependent on the Ce3+:Ce4+. Results have shown that the particles engineered with higher concentrations of Ce4+ on the surface are more robust and retain catalytic activity post buffer exposure.