Cerium oxide nanoparticles have been shown to have profound biological effects in cell culture and animal experiments. These same effects have not been seen in experiments with micron-sized ceria. [1-2] Nanosize ceria has extended the lifespan of mixed brain cell cultures by six fold, and the lives of Drosophila significantly. Results so far suggest that the increased lifespan is related to the mitigation of free radical damage due to UV-light, H2O2, and excitotoxicity (overactive signaling) by the ceria nanoparticles. In-vitro experiments show that the ceria nanoparticles are acting as free radical scavengers. The size, zeta potential, and BET surface area of ceria particles from two different sources were measured and related to the free radical scavenging rates for selected model radical species. The effects of coating the ceria with soluble polymer were investigated. These polymers include Pluronics PEO-PPO triblock copolymers and PEO chains anchored to the ceria using ion-containing anchor blocks. Finally, the scavenging rates were related qualitatively to the ratio of Ce+3/Ce+4 which is believed to be one of the factors controlling the scavenging mechanism.

1. B.A. Rzigalinski, D. Bailey, L. Chow, S.C. Kuiry, S. Patil, S. Merchant, and S. Seal. Faseb Journal, 2003, 17, pp A606-A606.

2.E.T. Strawn, C.A. Cohen, and B.A. Rzigalinski. Faseb Journal, 2006, 20, pp A1356-A1356.