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EFFECTS OF GRAPHENE OXIDE EXPOSURES ON THE MARINE BIVALVE, Crassostrea virginica
Citation:
Khan, B., A. Adeleye, R. Burgess, S. Russo, AND K. Ho. EFFECTS OF GRAPHENE OXIDE EXPOSURES ON THE MARINE BIVALVE, Crassostrea virginica. Aquaculture 2019, New Orleans, LA, March 07 - 11, 2019.
Impact/Purpose:
With increasing use of graphene family nanomaterials in the field of filtration devices, electronics, material coatings, and biomedicine, it is likely that graphene oxide (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. The overall goal of this work is to evaluate responses of marine organisms to environmental exposures to carbon-based nanoparticles such as GO.
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. However, current literature on such impacts is limited, especially in marine ecosystems. 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 molecular markers of GO toxicity using a static renewal design. Oysters were exposed to 0, 2.5 or 5 mg/L GO suspended in 0.22 µm filtered natural seawater. At the end of the exposures, gills and digestive glands were harvested for biochemical analyses. Water samples were analyzed for GO concentration using UV-Vis spectroscopy and for effective diameter and particle size distribution using dynamic light scattering. Oxidative damage was measured as lipid peroxidation using a malondialdehyde (MDA) assay and glutathione-s-transferase (GST) activity was measured as an enzyme marker to evaluate the effects of GO exposures on oysters. Elevated lipid peroxidation was observed in both tissues of the 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 cellular changes show that exposures to GO at concentrations ≥ 2.5 mg/L result in oxidative damage and upregulation of detoxification enzymes. This study advances our understanding of the nanotoxicity of an emerging contaminant and allows identification of biomarkers and putative molecular initiating events for the development of Adverse Outcome Pathways (AOPs).