Reactive oxygen species scavenging properties of ZrO2-CeO2 solid solution nanoparticles

Aims: The hypothesis that an increase in defects in cerium oxide (CeO2) nanoparticles induced by solid solutions with differences in valency and ionic radius of the solute will yield superior reactive oxygen species (ROS) scavengers at room temperature will be tested. Methods: Solid solutions of zirconium in CeO2, that is, CexZr1-xO2 nanoparticles, were synthesized by a reverse micelle method. Their crystal structures, particle sizes and level of agglomeration were characterized. The nanoparticles' activities to scavenge ROS were tested in response to hydrogen peroxide at physiological levels and room temperature using an enzyme peroxidase-based assay. Results: Solid solutions of Zr in CeO2 nanoparticles enhanced ROS scavenging fourfold. The hypothesis is confirmed that more defects are formed and that the scavenging activities of CexZr1-xO2 correlate to the nanoparticles' oxygen-storage capacity. Conclusions: The antioxidant efficacy of CeO2 nanoparticles can be enhanced by dissolving zirconium in the CeO2 lattice. The CexZr1-xO2 nanoparticles act as an enhanced catalyst at room temperature that scavenges ROS. Increased efficacy will enable lower nanoparticle dosages to protect cells from ROS, thus increasing the therapeutic width of these compounds.