Iron oxide nanoparticles may damage to the neural tissue through iron accumulation, oxidative stress, and protein aggregation

In the recent decade, iron oxide nanoparticles (IONPs) have been proposed for several applications in the central nervous system (CNS), including targeting amyloid beta (Aβ) in the arteries, inhibiting the microglial cells, delivering drugs, and increasing contrast in magnetic resonance imaging. Conversely, a notable number of studies have reported the role of iron in neurodegenerative diseases. Therefore, this study has reviewed the recent studies to determine whether IONPs iron can threaten the cellular viability same as iron. Iron contributes in Fenton's reaction and produces reactive oxygen species (ROS). ROS cause to damage the macromolecules and organelles of the cell via oxidative stress. Iron accumulation and oxidative stress are able to aggregate some proteins, including Aβ and α-synuclein, which play a critical role in Alzheimer's and Parkinson's diseases, respectively. Iron accumulation, oxidative stress, and protein aggregation make a positive feedback loop, which can be toxic for the cell. The release of iron ions from IONPs may result in iron accumulation in the targeted tissue, and thus, activate the positive feedback loop. However, the levels of IONPs induced toxicity depend on the size, concentration, surface charge, and the type of coating and functional groups of IONPs. IONPs depending on their properties can lead to iron accumulation, oxidative stress and protein aggregation in the neural cells. Therefore, in order to apply IONPs in the CNS, the consideration of IONPs properties is crucial.