Year of Publication

2014

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Plant and Soil Sciences

First Advisor

Dr. Jason Unrine

Abstract

Manufactured CeO2 nanomaterials (CeO2-MNMs) are used for a wide variety of applications including diesel fuel additives and chemical/mechanical planarization media. To test the effects of CeO2-MNM surface coating charge on to model organism Caenorhabditis elegans, we synthesized 4 nm CeO2 with cationic (DEAE-), anionic (CM-), and neutral (DEX) coatings. In L3 nematodes exposed for 24 hours, DEAE-CeO2 induced lethality at lower concentrations than CM- or DEX-CeO2. Feeding slightly decreased CeO2 toxicity, regardless of coating. In L2 nematodes exposed for 48 hours with feeding, DEAE-CeO2 caused lethality at the lower concentrations as compared to CM- and DEX-CeO2. Sublethal effects were measured by observing reproduction and oxidative/nitrosative protein damage. Low concentrations of DEAE-CeO2 induced similar reductions as CM- and DEX-CeO2 that were two orders of magnitude higher. Using immunochemical slot blots to explore oxidative/nitrosative stress, no treatments produced significant changes in protein carbonyl or 3-nitrotyrosine formation; however, the statistical power of our assay was low. All treatments caused large but not statistically significant increases in protein carbonyl levels. DEAE-CeO2 exposure caused a significant reduction in 4-hydroxy-2-nonenol levels. This research suggests that cationic coatings render CeO2 significantly more toxic to C. elegans than neutral or anionic coatings.