Iron oxide/silver hybrid nanoparticles impair the cholinergic system and cause reprotoxicity in Caenorhabditis elegans

Abstract

Iron oxide nanoparticles present superparamagnetic properties that enable their application in various areas, including drug delivery at specific locations in the organism. Silver nanoparticles have potent antimicrobial effects. Although the combination of Fe₃O₄-NPs and Ag-NPs in one hybrid nanostructure (Fe₃O₄@Ag-NPs) demonstrated promising targeted biomedical applications, their toxicological effects are unknown and need to be assessed. Caenorhabditis elegans is a promising model for nanotoxicological analysis, as it allows an initial screening of new substances. After exposure to Fe₃O₄-NPs, Ag-NPs and Fe₃O₄@Ag-NPs, we observed that hybrid NPs reduced the C. elegans survival and reproduction. Higher concentrations of Fe₃O₄@Ag-NPs caused an increase in cell apoptosis in the germline and a decrease in egg laying, which was associated with a decrease in worm swimming movements and abnormalities in the cholinergic neurons. Fe₃O₄@Ag-NPs caused an increase in reactive oxygen species, along with activation of DAF-16 transcription factor. A higher expression of the target genes GST-4::GFP and SOD-3::GFP were evidenced, which suggests the activation of the antioxidant system. Our results indicate the reprotoxicity caused by high levels of Fe₃O₄@Ag-NPs, as well as cholinergic neurotoxicity and activation of the antioxidant system in C. elegans, suggesting that high concentrations of these nanomaterials can be harmful to living organisms.

Keywords: Hybrid nanoparticles; Metal NPs; Nanotoxicology; Reproduction.