Chemical transformation and cytotoxicity of iron oxide nanoparticles (IONPs) accumulated in mitochondria.

ABSTRACT

Iron oxide nanoparticles (IONPs) have been widely used as a nanoscale tool in biomedical research. However, it remains largely unknown how IONPs are transformed at a subcellular level to elicit distinct biological effects. In the present study, we prepared three different IONPs, including two IONPs targeting mitochondria (IONP-TPP) and lysosomes (IONP-APM), respectively, and a control with no specified target (IONP). By MTT assay and JC-1 staining, mitochondria-targeted IONP-TPP was found to produce significant cytotoxicity and severe mitochondrial membrane depolarization in MCF-7 cells. Furthermore, X-ray absorption spectroscopy (XAS) analysis revealed that IONP-TPP underwent remarkable edge defects and oxidation inside the cell. These findings suggest that IONPs are prone to the chemical transformation at mitochondria, and mitochondria are vulnerable to IONPs accumulation in the cell.