In this work, the physicochemical characterization of five (Al₂O₃, In₂O₃, Mn₃O₄, SiO₂ and SnO₂) nanoparticles (NPs) was carried out. In addition, the evaluation of the possible toxic impacts of these NPs and the respective modes of action were performed using the yeast Saccharomyces cerevisiae. In general, in aqueous suspension, metal(loid) oxide (MOx) NPs displayed an overall negative charge and agglomerated; these NPs were practically insoluble (dissolution < 8%) and did not generate detectable amounts of reactive oxygen species (ROS) under abiotic conditions. Except In₂O₃ NPs, which did not induce an obvious toxic effect on yeast cells (up to 100 mg/L), the other NPs induced a loss of cell viability in a dose-dependent manner. The comparative analysis of the loss of cell viability induced by the NPs with the ions released by NPs (NPs supernatant) suggested that SiO₂ toxicity was mainly caused by the NPs themselves, Al₂O₃ and SnO₂ toxic effects could be attributed to both the NPs and the respective released ions and Mn₃O₄ harmfulness could be mainly due to the released ions. Al₂O₃, Mn₃O₄, SiO₂ and SnO₂ NPs induced the loss of metabolic activity and the generation of intracellular ROS without permeabilization of plasma membrane. The co-incubation of yeast cells with MOx NPs and a free radical scavenger (ascorbic acid) quenched intracellular ROS and significantly restored cell viability and metabolic activity. These results evidenced that the intracellular generation of ROS constituted the main cause of the cytotoxicity exhibited by yeasts treated with the MOx NPs. This study highlights the importance of a ROS-mediated mechanism in the toxicity induced by MOx NPs.

• PMID: 31152204
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Journal Article

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Sousa CA, Soares HMVM, Soares EV

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