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Study of Quantum Dots (CdS, ZnS) toxicity in Danio rerio, Daphnia magna and HepG2 cell line
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The increasing use of nanoparticles in recent decades led to a growing concern about the possible consequences for the environment. The present study aims to evaluate the toxicity of the Quantum Dots (QDs) (ZnS and CdS), using Danio rerio, Daphnia magna and HepG2 cell line. Both organisms were exposed to different concentrations of QDs (10, 100 and 1000 µg/L), singly and combined, to assess toxicity. Several biochemical analyses were performed: antioxidant enzymes (Catalase, Glutathione-Stransferase and Superoxide Dismutase), total antioxidant capacity (TAC), ubiquitin, heat shock proteins (HSPs) and lipid peroxidation (MDA content). An HepG2 cell line was also exposed to the same QDs concentrations, and cell viability was assessed. QDs were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Dynamic light scattering (DLS). The results from exposure assays showed that the concentrations of QDs tested did not cause mortality in fish but resulted in high mortality rates in Daphnia magna exposed to higher QDs concentrations (100 and 1000 µg/L). Regarding HepG2 assay, QDs were not able to cause significant cytotoxicity. Overall, the results from fish and Daphnids assays showed sub-lethal effects following exposure to the different concentrations of QDs. D. rerio exposure assays showed increased levels of antioxidant enzymes, HSP70 and Ubiquitin in fish exposed to 100 µg/L QDs (ZnS). D. magna exposure assays revealed decreased levels of antioxidant enzymes and increased levels of Ubiquitin according to QDs concentrations tested. Was investigated the trophic transfer of QDs from D. magna (previously exposed to QDs) to D. rerio. The results from Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis indicate that the QDs (and/or their ions released into the aqueous medium) were ingested by Daphnia and then transferred to fish via ingestion as well.
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Quantum Dots Danio rerio Daphnia magna HepG2 Oxidative stress Toxicity