Biophysical, molecular dynamics and cellular studies on the interaction of nickel oxide nanoparticles with tau proteins and neuron-like cells.

Nickel oxide nanoparticles (NiO NPs) have been used in the biological and medical sciences. However, their toxic effects against biological systems such as nervous system have not been well studied. Therefore, the adverse effect of NiO NPs on tau structure was investigated by fluorescence and CD spectroscopic methods as well as TEM study. Also, molecular dynamic study was run to extend the experimental data. Cytotoxic activity of NiO NPs against SH-SY5Y cell was determined by trypan blue exclusion, cell morphology, ROS, and apoptosis assays. ANS, Nile red, ThT assays and electron micrograph investigation revealed that NiO NPs can increase the hydrophobic portions of tau and induce the formation of amorphous tau aggregates. Far and near CD spectroscopic methods revealed that NiO NPs can change the secondary and tertiary structure of tau, respectively. Theoretical studies depicted that NiO NPs lead to folding of tau structure. In the cellular view, NiO NPs induced significant mortality and morphological effects against SH-SY5Y cells. NiO NPs also provided a significant impact on generating intracellular ROS and apoptosis induction. This study determined that NiO NPs could mediate the induction of some undesired effects on the nervous system.