US EPA

607718 

Journal Article 

The role of cerium redox state in the SOD mimetic activity of nanoceria 

Heckert, EG; Karakoti, AS; Seal, S; Self, WT 

2008 

Yes 

Biomaterials
ISSN: 0142-9612
EISSN: 1878-5905 

29 

18 

2705-2709 

Abstract: Cerium oxide nanoparticles (nanoceria) have recently been shown to protect cells against oxidative stress in both cell culture and animal models. Nanoceria has been shown to exhibit superoxide dismutase (SOD) activity using a ferricytochrome C assay, and this mimetic activity that has been postulated to be responsible for cellular protection by nanoceria. The nature of nanoceria's antioxidant properties, specifically what physical characteristics make nanoceria effective at scavenging superoxide anion, is poorly understood. In this study electron paramagnetic resonance (EPR) analysis confirms the reactivity of nanoceria as an SOD mimetic. X-ray photoelectron spectroscopy (XPS) and UV–visible analyses of nanoceria treated with hydrogen peroxide demonstrate that a decrease in the Ce 3⁺/4⁺ ratio correlates directly with a loss of SOD mimetic activity. These results strongly suggest that the surface oxidation state of nanoceria plays an integral role in the SOD mimetic activity of nanoceria and that ability of nanoceria to scavenge superoxide is directly related to cerium(III) concentrations at the surface of the particle. [Copyright 2008 Elsevier] Copyright of Biomaterials is the property of Elsevier Science Publishing Company, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts) 

SUPEROXIDE; OXYGEN; CERIUM oxides; ELECTRON paramagnetic resonance