Toxicity of different zinc oxide nanomaterials and dose-dependent onset and development of Parkinson’s disease-like symptoms induced by zinc oxide nanorods


With the increasing applications in various fields, the release and accumulation of zinc oxide (ZnO) nano-materials ultimately lead to unexpected consequences to environment and human health. Therefore, toxicity comparison among ZnO nanomaterials with different shape/size and their adverse effects need better charac-terization. Here, we utilized zebrafish larvae and human neuroblastoma cells SH-SY5Y to compare the toxic effects of ZnO nanoparticles (ZnO NPs), short ZnO nanorods (s-ZnO NRs), and long ZnO NRs (l-ZnO NRs). We found their developmental- and neuro-toxicity levels were similar, where the smaller sizes showed slightly higher toxicity than the larger sizes. The developmental neurotoxicity of l-ZnO NRs (0.1, 1, 10, 50, and 100 μg/mL) was further investigated since they had the lowest toxicity. Our results indicated that l-ZnO NRs induced develop-mental neurotoxicity with hallmarks linked to Parkinsons disease (PD)-like symptoms at relatively high doses, including the disruption of locomotor activity as well as neurodevelopmental and PD responsive genes expres-sion, and the induction of dopaminergic neuronal loss and apoptosis in zebrafish brain. l-ZnO NRs activated reactive oxygen species production, whose excessive accumulation triggered mitochondrial damage and mito-chondrial apoptosis, eventually leading to PD-like symptoms. Collectively, the developmental- and neuro-toxicity of ZnO nanomaterials was identified, in which l-ZnO NRs harbors a remarkably potential risk for the onset and development of PD at relatively high doses, stressing the discretion of safe range in view of nano-ZnO exposure to ecosystem and human beings.

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