Copper oxide nanoparticles inhibit the metabolic activity of Saccharomyces cerevisiae

Abstract

Copper oxide nanoparticles (CuO NPs) are used increasingly in industrial applications and consumer products and thus may pose risk to human and environmental health. The interaction of CuO NPs with complex media and the impact on cell metabolism when exposed to sublethal concentrations are largely unknown. In the present study, the short-term effects of 2 different sized manufactured CuO NPs on metabolic activity of Saccharomyces cerevisiae were studied. The role of released Cu(2+) during dissolution of NPs in the growth media and the CuO nanostructure were considered. Characterization showed that the 28 nm and 64 nm CuO NPs used in the present study have different primary diameter, similar hydrodynamic diameter, and significantly different concentrations of dissolved Cu(2+) ions in the growth media released from the same initial NP mass. Exposures to CuO NPs or the released Cu(2+) fraction, at doses that do not have impact on cell viability, showed significant inhibition on S. cerevisiae cellular metabolic activity. A greater CuO NP effect on the metabolic activity of S. cerevisiae growth under respiring conditions was observed. Under the tested conditions the observed metabolic inhibition from the NPs was not explained fully by the released Cu ions from the dissolving NPs.

Copper Oxide Nanoparticles Impact Several Toxicological Endpoints and Cause Neurodegeneration in Caenorhabditis elegans

“…elegans [5]. The copper oxide (CuO) NPs used throughout this study have been previously characterized by transmission electron microscopy [8] and were observed to be predominantly spherical with a rough surface and an average primary particle diameter of 28.4 nm and a parallel crystal lattice fringe spacing of 2.4 Å. When dispersed in nematode growth K medium, the CuO NPs undergo changes in the hydrodynamic diameter (Fig 1).…”

“…Transmission electron microscopy was performed on the CuO NPs, and they were found to be uniform in both shape and size, spherical with an average diameter of 28 nm [8]. The CuO NPs were diluted into sterile K medium at optimal concentrations (2.5 mg CuO/L) for hydrodynamic characterization using NS500 platform (Nanosight Ltd).…”

“…NPs solutions were injected into the viewing chamber equipped with 640-nm laser and measurements were taken at room temperature. The Nanosight measurement was performed as previously without modification [8]. To determine the CuO NPs average diameter, the nanoparticle tracking analysis 2.0 Build 127 analytical software was used.…”

“…CuO NPs release Cu ions into natural and synthetic aqueous media, meaning the observed cytotoxic or inhibitory effects could be the result of either the nanoparticle structure or the free Cu ions [7,8]. Toxicity caused by CuO nanoparticles and free Cu ions are commonly related to the high redox activity of Cu [4,9].…”

“…The released copper ions from CuO NPs has been suggested as the sole source of toxicity in earthworms, several algae and crustacean species, Escherichia coli , and human cell lines [1]. By contrast, other studies suggest the NP component also contributes to inhibition of cellular metabolic activity [8] and cytotoxicity in yeast [11] and plants [12]. Toxicological endpoints of CuO NPs have been reported for many model organisms, including bacteria [7], yeast [11], Oligochaeta [13], and human cell lines [14].…”