Nickel oxide nanoparticles induce toxicity in yeasts via oxidative stress

Abstract

[Excerpt] The increasing use of nickel oxide (NiO) nanoparticles (NPs) raises concerns about their potential toxicity. In the present study, the yeast Saccharomyces cerevisiae was used, as a cell model, in order to elucidate whether the toxicity of NiO NPs is associated with the oxidative stress (OS). In abiotic conditions (cell free), NiO NPs were unable to induce the generation of reactive oxygen species (ROS), which excludes the possibility of exerting a pro-oxidant effect. However, yeast cells exposed to NiO NPs accumulated intracellularly superoxide anions (assessed with dihydroethidium) and hydrogen peroxide (evaluated with 2′,7′-dichlorodihydrofluorescein diacetate or dihydrorhodamine 123) when incubated in normal (oxygen) atmosphere. Yeast cells exposed to NiO also presented reduced cell viability (measured through a clonogenic assay). Yeasts co-exposed to NiO NPs and the antioxidants L-ascorbic acid (a scavenger of free radicals) or N-tertbutyl-α-phenylnitrone (a spin trapping agent) presented ROS quenching and increased cell viability, which suggests that NiO toxicity is linked to ROS production. [...]