Cytotoxic and genotoxic effects of cadmium sulfide nanoparticles

Abstract

Cadmium compounds are highly toxic substances characterized by mutagenic, genotoxic and carcinogenic effects, and having high cumulative properties. Application of cadmium nanoparticles (NPs) in medicine stimulates the study of their mechanism of action at the cellular level and at the level of organs and systems, determination of biomarkers of their action, particularly in comparison with the ionic form. The aim of the study was to compare the features of cytotoxic and genotoxic effects of cadmium sulfide (CdS) NPs of different sizes on cell cultures of different histogenesis with those of cadmium chloride (CdCl2). Materials and Methods: In this work, we used cadmium compounds in the nanoform: NPs CdS of 4–6 nm and of 9–11 nm in size; and in the ionic form: CdCl2. The studies were conducted in vitro in cell lines — IMR-32, НEК-293 and MАEC. To count viable cells we compared the results of three basic tests: MTT (methyl tetrasolium test), SRB (sulforhodamine B test) and NRU (neutral red uptake test). We evaluated the genotoxic effect of the substances studied in vitro using DNA comet assay in alkaline conditions. Results: CdS NPs and CdCl2 demonstrated pronounced dose-dependent cytotoxic effect in MАEC, НEК-293 and IMR-32 cell lines, by impairing membrane permeability, functioning of mitochondria and lysosomes, and inhibiting the function of protein synthesis. Cytotoxic effect of CdCl2 was the most pronounced, this effect of CdS NPs of 9–11 nm in size being the least pronounced. The comet DNA assay in alkaline conditions revealed a statistically significant increase in DNA comet index when exposed to CdCl2 and CdS NPs in comparison with the negative control, which indicates their genotoxic effect. CdS NPs of 4–6 nm in size showed a more pronounced effect in comparison with those of 9–11 nm in size. Conclusion: Elucidation of mechanisms underlying the implementation of toxic effects of cadmium NPs will help in assessing the potential risks associated with their use in industry and developing effective preventive measures. For instance, when planning in vivo studies for toxicological evaluation of nanomaterials and nano-substances containing NPs of cadmium, it is necessary to investigate the mutagenic and carcinogenic risks and to take into account the high likelihood of neurotoxic and cardiovasotoxic effects, along with nephrotoxic effects, since high cytotoxic activity of the investigated compounds of cadmium was detected on the cells of the MАEC line (endothelial origin) and IMR-32 (neuronal origin). Key Words: cadmium, nanoparticles, cell culture, cytotoxicity, genotoxicity.