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The effect of cerium oxide nanoparticle valence state on reactive oxygen species and toxicity.

Dunnick KM; Pillai R; Pisane KL; Stefaniak AB; Sabolsky EM; Leonard SS

Biol Trace Elem Res 2015 Jul; 166(1):96-107

https://doi.org/10.1007/s12011-015-0297-4

20045975

Cerium oxide (CeO2) nanoparticles, which are used in a variety of products including solar cells, gas sensors, and catalysts, are expected to increase in industrial use. This will subsequently lead to additional occupational exposures, making toxicology screenings crucial. Previous toxicology studies have presented conflicting results as to the extent of CeO2 toxicity, which is hypothesized to be due to the ability of Ce to exist in both a +3 and +4 valence state. Thus, to study whether valence state and oxygen vacancy concentration are important in CeO2 toxicity, CeO2 nanoparticles were doped with gadolinium to adjust the cation (Ce, Gd) and anion (O) defect states. The hypothesis that doping would increase toxicity and decrease antioxidant abilities as a result of increased oxygen vacancies and inhibition of +3 to +4 transition was tested. Differences in toxicity and reactivity based on valence state were determined in RLE-6TN rat alveolar epithelial and NR8383 rat alveolar macrophage cells using enhanced dark field microscopy, electron paramagnetic resonance (EPR), and annexin V/propidium iodide cell viability stain. Results from EPR indicated that as doping increased, antioxidant potential decreased. Alternatively, doping had no effect on toxicity at 24 h. The present results imply that as doping increases, thus subsequently increasing the Ce3+/Ce4+ ratio, antioxidant potential decreases, suggesting that differences in reactivity of CeO2 are due to the ability of Ce to transition between the two valence states and the presence of increased oxygen vacancies, rather than dependent on a specific valence state.

Nanotechnology; Cerium-compounds; Solar-energy; Gas-indicators; Exposure-limits; Risk-factors; Toxicology; Antioxidants; Author Keywords: Cerium oxide; Nanotoxicology; Reactive oxygen species; Toxicity; Valence state

K. M. Dunnick; National Institute for Occupational Safety and Health, HELD, 1095 Willowdale Rd, Morgantown, WV 26505

BTERDG

1306-38-3

20150701

Journal Article

kdunnick@mix.wvu.edu

2015

1

0163-4984

HELD; DRDS

Manufacturing

Biological Trace Element Research

WV