Responses of Eastern Oysters to graphene oxide nanomaterial exposures
Citation:
Khan, B., A. Adeleye, R. Burgess, S. Russo, AND K. Ho. Responses of Eastern Oysters to graphene oxide nanomaterial exposures. Pollutant Responses In Marine Organisms, Charleston, South Carolina, May 19 - 22, 2019.
Impact/Purpose:
The overall goal of this work is to evaluate responses of marine organisms to environmental exposures to carbon-based nanoparticles such as graphene oxide (GO). With increasing use of graphene family nanomaterials in the field of filtration devices, electronics, material coatings, and biomedicine, it is likely that GO nanoparticles will make their way into aquatic ecosystems. Our knowledge of the environmental effects of such nanoparticles is very limited. This research aims at understanding the impacts and toxicity of GO exposures in marine habitats using Eastern oysters as a model organism.
Description:
Graphene is a two-dimensional nanomaterial composed of sp2 hybridized carbon atoms with unique mechanical, thermal, electrical, and optical properties. Due to their high strength and light weight, graphene family nanomaterials (GFNs), such as graphene oxide (GO) are increasingly being used in the fields of electronics, medicine, surface coatings, and filtration devices. With a rapidly growing consumer market, the concern for environmental impacts of GFNs is rising and there is an urgent need to evaluate the associated risks for marine organisms. The overall aim of this work is to evaluate the effects of GO on a marine filter-feeding bivalve species, Crassostrea virginica (Eastern oysters). A 14-day study was conducted to identify biomarkers of GO toxicity using a static renewal exposure design. Oysters were exposed to 0, 2.5 or 5 mg/L GO suspended in filtered natural seawater. Water samples were analyzed using UV-Vis spectroscopy and dynamic light scattering for GO concentration and size assessments, respectively. At the end of the exposures, gill and digestive gland tissues were harvested for biochemical analyses. Cellular oxidative damage was measured as lipid peroxidation using a malondialdehyde assay and glutathione-s-transferase (GST) activity was used as an enzyme marker to evaluate GO-induced effects. Both gills and digestive gland tissues showed elevated lipid peroxidation in GO-exposed oysters which suggested reactive oxygen species induced oxidative stress. Changes in GST activities were also noted that are indicative of induction of toxicity pathways as well as cellular signaling. Together, these changes show that GO exposures at concentrations ≥ 2.5 mg/L result in oxidative damage and upregulation of detoxification enzymes. This study advances our understanding of nanotoxicity of an emerging contaminant and contributes to identification of putative molecular initiating events towards the development of Adverse Outcome Pathways (AOPs).