Oxidative Stress-Induced DNA Damage by Manganese Dioxide Nanoparticles in Human Neuronal Cells

Metal nanoparticles have been extensively used in industry as well as in biomedical application. In this work, we have evaluated the toxic potential of manganese dioxide (MnO₂) nanoparticles (MNPs) on human neuronal (SH-SY5Y) cells. Cellular toxicity due to MNPs (0, 10, 30, and 60 μg/ml) on the SH-SY5Y cell was observed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) tests. MNPs produced reactive oxygen species (ROS) and declined in mitochondrial membrane potential in the SH-SY5Y cell in dose and duration dependent manner. Moreover, lipid peroxide (LPO), superoxide dismutase (SOD), and catalase (CAT) activities were increased and glutathione was reduced in dose and time dependent manner. A significant upgrade in Hoechst 33342 fluorescence intensity (chromosome condensation) and phosphatidylserine translocation (apoptotic cell) was visualized in cells treated with MNPs for 48 h. On the other hand, caspase-3 activity was increased due to MNPs in SH-SY5Y cells. DNA strand breaks were determined by alkaline single cell gel electrophoresis assay (Comet Assay) and maximum fragmentation of DNA produced due to MNPs (60 μg/ml) for 48 hours. This result provides a basic mechanism of induction of apoptosis and toxicity by MNPs in SH-SY5Y cells.