The role of charge in the toxicity of polymer-coated cerium oxide nanomaterials to Caenorhabditis elegans

Abstract

This study examined the impact of surface functionalization and charge on ceria nanomaterial toxicity to Caenorhabditis elegans. The examined endpoints included mortality, reproduction, protein expression, and protein oxidation profiles. Caenorhabditis elegans were exposed to identical 2-5nm ceria nanomaterial cores which were coated with cationic (diethylaminoethyl dextran; DEAE), anionic (carboxymethyl dextran; CM), and non-ionic (dextran; DEX) polymers. Mortality and reproductive toxicity of DEAE-CeO was approximately two orders of magnitude higher than for CM-CeO or DEX-CeO. Two-dimensional gel electrophoresis with orbitrap mass spectrometry identification revealed changes in the expression profiles of several mitochondrial-related proteins and proteins that are expressed in the C. elegans intestine. However, each type of CeO material exhibited a distinct protein expression profile. Increases in protein carbonyls and protein-bound 3-nitrotyrosine were also observed for some proteins, indicating oxidative and nitrosative damage. Taken together the results indicate that the magnitude of toxicity and toxicity pathways vary greatly due to surface functionalization of CeO nanomaterials.

Synchrotron XRF Analysis Identifies Cerium Accumulation Colocalized with Pharyngeal Deformities in CeO2 NP-Exposed Caenorhabditis elegans

“…Due to changes in the expression of various proteins, associated primarily with the intestine of C. elegans , a previous study has identified the gut lining as an important target for nanoceria toxicity. 40 Similar to the current study, hyperspectral imaging of CeO 2 NP in C. elegans indicated the presence of particles in the gut of the nematodes. 16 Following the exposure to 12.5 mg Ce L –1 CeO 2 NPs (53 ± 3 nm) in MHRW, high-density areas, believed to be particle aggregates within the gut of the nematode, were visible on hyperspectral dark-field images.…”

“…Exposure to Ce NP induced only minor toxic responses, in agreement with the low retention of the CeO 2 NPs within nematodes ( Figure S5, Tables S1 and S2 ). However, Arnold et al 16 reported that CeO 2 NPs (53.34 ± 3.12 nm) were more toxic than the equimolar bulk CeO 2 to C. elegans ; Arndt et al 40 concluded that the level of toxicity toward C. elegans was highly dependent on the surface charge of the particles. In the current study, we identified a change from positive (34 mV) to negative (−10 mV) charge of the NPs in ddH 2 O or MHRW, respectively, suggesting a loss of stability in the exposure media (MHRW).…”

The Influence of Surface Coatings of Silver Nanoparticles on the Bioavailability and Toxicity to Elliptio complanata Mussels

“…It is generally recognized that negative charges at the surface of the nanoparticle result generally in less toxicity compared to a positively charged surface [5]. In another study, the toxicity of positively coated and negatively coated cerium oxide nanoparticles was examined in C. elegans and revealed that mortality and reproductive toxicity were 2 orders of magnitude higher with a positively charge coating (diethylaminoethyl dextran) than with negatively charged (carboxymethyl dextran) and neutral (dextran) coatings [11].…”

The preparation temperature influences the physicochemical nature and activity of nanoceria

“…Nanoceria has the potential to act as a pro-or antioxidant, depending on its valence, and the oxidative stress level of the system under study. Solvothermally synthesized nanoceria increased protein carbonyls in rats and Caenorhabditis elegans that were not induced by oxidative stress [71,72]. In models of oxidative stress, nanoceria decreased elevated levels of protein carbonyls in the lung and hippocampus of hypoxic rats [73,74], in the kidney of diabetic mice [75], in murine embryo tissue in a model of gestational diabetes [76], and in the right ventricle of rats with monocrotaline-induced hypertension [77].…”