The role of valence state in cerium oxide nanoparticle toxicity

Details

• Personal Author:
  Dunnick KM ; Leonard, Stephen S. ; Sabolsky EM
• Description:
  Nanoparticles are part of an emerging field of technology that offers unique manufacturing and engineering properties not easily attainable with micron or larger particles of similar chemical composition. Cerium oxide (CeO2) nanoparticles are one such material used in a variety of products, including solar cells and gas sensors. Increased industrial production 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 theorized to be due to the ability of Ce to exist in both a +3 and +4 valence state. Thus, to study whether valence state is important in CeO2 toxicity, CeO2 nanoparticles were doped with gadolinium (Gd) to adjust Ce toward a +3 state. We hypothesized that doping would increase toxicity and decrease antioxidant abilities as a result of increased oxygen vacancies and inhibition of +3 to +4 transition. RLE-6TN rat alveolar epithelial and NR8383 rat alveolar macrophage cells were treated with a range of CeO2 doses to assess toxicity using an annexin V/ propidium iodide stain, and neither doped nor pure CeO2 induced toxicity by 24 hrs. Darkfield microscopy was employed to observe nanoparticle-cellular interactions, and within 5 min both pure and doped CeO2 began to associate with cells. Electron spin resonance, used to assess the effects of CeO2 on free radical production, showed that with doping, antioxidant potential decreased. Further, Nrf2 activity and downstream antioxidant proteins, such as heme oxygenase-1, were quantified via western blot and immunocytochemistry to elucidate important antioxidant pathways. The results suggest that valence state plays a role in antioxidant potential but a minimal role in cytotoxicity; however, further studies are needed to understand the mechanisms by which CeO2 valence state affects toxicity. [Description provided by NIOSH]
• Subjects:
  Antioxidants Chemistry Environmental Monitoring Histocytochemistry Immune System Lung Metals Microbiology Occupational Health Respiratory System Safety Toxicology

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• Keywords:
  Alveolar-cells Analytical-instruments Analytical-processes Cellular-reactions Cerium-compounds Chemical-composition Chemical-structure Cytochemistry Dioxides Exposure-assessment Free-radical-generation Immunochemistry Iodimetric-analysis Lung-cells Metal-compounds Metal-oxides Microscopic-analysis Nanotechnology Oxides

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  California ; OSHA Region 3 ; OSHA Region 9 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  144
• Issue:
  1
• NIOSHTIC Number:
  nn:20045992
• Citation:
  Toxicologist 2015 Mar; 144(1):417
• CAS Registry Number:
  Ceria (CAS RN 1306-38-3)
• Federal Fiscal Year:
  2015
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 54th Annual Meeting and ToxExpo, March 22-26, 2015, San Diego, California
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:53e5fd7900b493c967525fc4e623c4cfedaf0dd04725257bbd840c8644ee24710882cdcbe308a73e1f54758eeee110de7a6ffa5e4b0f92bb8969ffdbd42fec46
• Download URL:
  https://stacks.cdc.gov/view/cdc/201191/cdc_201191_DS1.pdf
• File Type:
  [PDF - 230.44 KB ]