ABSTRACT
Graphene exhibits unique physical and chemical properties that facilitate its application in many fields, including electronics and biomedical areas. However, the use of graphene and its derivatives could result in accumulation in aquatic environments, and the risks posed by these compounds for organisms are not completely understood. In this study, we investigated the effects of graphene oxide (GO) on adult zebrafish (Danio rerio). Experimental fish were exposed to 2, 10 or 20mgL-1 GO, and the cytotoxicity, genotoxicity and oxidative stress were assessed. The morphology of the gills and liver tissues was also analyzed. Graphene oxide exposure led to an increase in the number of gill cells that were in early apoptotic and necrotic stages, but genotoxicity was not observed in blood cells. We also observed the generation of Reactive Oxygen Species (ROS) in gill cells. Structural analysis revealed injuries to gill tissues, including a dilated marginal channel, lamellar fusion, clubbed tips, swollen mucocytes, epithelial lifting, aneurysms, and necrosis. Liver tissues also presented lesions such as peripherally located nuclei. Furthermore, hepatocytes exhibited a non-uniform shape, picnotic nuclei, vacuole formation, cell rupture, and necrosis. Our results showed that sub-lethal doses of graphene oxide could be harmful to fish species and thus represent risks for the aquatic food chain.
Subject(s)
Graphite/toxicity , Toxicity Tests , Zebrafish/growth & development , Animals , Apoptosis/drug effects , DNA Damage , Female , Gills/drug effects , Gills/pathology , Liver/drug effects , Liver/pathology , Male , Microscopy, Atomic Force , Mutagens/toxicity , Nanoparticles/toxicity , Nanoparticles/ultrastructure , Necrosis , Reactive Oxygen Species/metabolism , Static Electricity , Water Pollutants, Chemical/toxicityABSTRACT
Nanostructured zinc oxide (ZnO) materials have been intensively studied because of their potential applications in cancer therapies. However, a better comprehension of the toxicity of the flower-like ZnO nanostructures toward cancer cells is still needed. In this study, we investigate the cytotoxicity of a ZnO flower-like nanostructure produced at low temperature via aqueous solution in human cervical carcinoma (HeLa) cells and noncancerous cell-line murine fibroblast (L929) cells. Nanotoxicology effects were analyzed to study apoptosis and necrosis processes, reactive oxygen species production, and cellular uptake. Cells remained incubated for 24 h in concentrations of 0.1, 1.0, and 10.0 µg mL-1 ZnO nanoparticles (NPs), with the estimated rods length varying from 1.7 ± 0.4 to 2.3 ± 0.4 µm, synthesized at different times (4, 2, and 0.5 h) by an aqueous solution method. The cytotoxic response observed in noncancerous and cancer cells showed that all of the ZnO NPs synthesized by an aqueous solution exhibited enhanced toxicology effects in cancer cells. ZnO flower-nanostructures exhibited a higher cytotoxic against cancer HeLa cells, in comparison to the noncancerous cell line L929. The cytotoxic response of ZnO NPs at 0.5, 2, and 4 h in L929 cells was not statistically significant. This ability may be of clinical interest because of the effectiveness of ZnO NPs to distinguish between normal and cancer cells in cancer therapy.