Cytotoxicity and apoptosis induction of copper oxide-reduced graphene oxide nanocomposites in normal rat kidney cells

Copper oxide-reduced graphene oxide nanocomposites (CuO-rGO NCs) have received great attention from researchers due to their exceptional physicochemical properties that cannot be achieved by a single composition. CuO-rGO NCs have the potential to be used in diverse fields including agriculture, cosmetic, textile, the food industry, and biomedicine. The growing application and production of CuO-rGO NCs raises the concern of their effects on human and the environmental health. Knowledge on the toxicolog-ical response of CuO-rGO NCs in biological systems is scarce. This study was aimed to explore the cyto-toxicity and apoptosis response of CuO-rGO NCs in normal rat kidney cells (NRR52E). CuO-rGO NCs was synthesized by a simple hydrothermal method using copper nitrate and graphene oxide (GO) as precur-sors. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS) confirmed the preparation of CuO-rGO NCs with high crystallinity, polygonal shape, smooth surface morphology. Besides, CuO nanoparticles were tightly anchored on rGO nanosheets. Biological results showed that CuO-rGO NCs induce a dose-dependent cytotoxicity in NRK52E cells evi-dent by cell viability reduction and irregular cellular morphology. Fluorescent microscopic examination of 2,7-dichlorofluorescin probe showed that CuO-rGO NCs generate intracellular reactive oxygen species (ROS) in NRK52E cells. Acridine orange/ethidium bromide dual staining depicted that number of orange -red stained cells (apoptotic cells) increases with increasing concentration of CuO-rGO NCs. The 40, 6-diamidino-2-phenylindole (DAPI) fluorescent staining exhibited that CuO-rGO NCs induce chromosomal condensation while normal-shaped nuclei were observed in the control cells. In cell cycle analysis, cells exposed to CuO-rGO NCs demonstrated significantly higher accumulation of apoptotic cells in subG1 phase. Altogether, we observed that CuO-rGO NCs induce cytotoxicity, ROS generation, and apoptosis in NRK52E cells. This preliminary study warrants future research to evaluate the potential mechanisms of CuO-rGO NCs toxicity at molecular level.& COPY; 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

CuO-rGO nanocomposites have attracted great attention due to their exceptional physicochemical properties. However, their effects on human and environmental health are not well understood. This study investigated the cytotoxicity and apoptosis response of CuO-rGO in normal rat kidney cells. The results showed that CuO-rGO induced cytotoxicity, generation of reactive oxygen species, and apoptosis. Further research is needed to elucidate the potential mechanisms of CuO-rGO toxicity at the molecular level.