The intensity of internalization and cytotoxicity of superparamagnetic iron oxide nanoparticles with different surface modifications in human tumor and diploid lung cells

: The human lung adenocarcinoma epithelial (A549) cells and the human embryo lung (HEL 12469) cells were used to investigate the uptake and cytotoxicity of magnetite nanoparticles (MNPs) with different chemically modified surfaces. MNPs uptake was an energy-dependent process substantially affected by the serum concentration in the culture medium. Internalized MNPs localized in vesicle-bound aggregates were observed in the cytoplasm, none in the nucleus or in mitochondria. All MNPs induced a dose- and time-dependent increase in cytotoxicity in both human lung cell lines. The cytotoxicity of MNPs increased proportionally with the particle size. Since the cytotoxicity of MNPs was nearly identical when the doses were equalized based on particle surface area, we suppose that the particle surface area rather than the surface modifications per se underlay the cytotoxicity of MNPs. In general, higher internalized amount of MNPs was found in HEL 12469 cells compared with A549 cells. Accordingly, the viability of the human embryo lung cells was reduced more substantially than that of the adenocarcinoma lung cells. The weak MNPs uptake into A549 cells might be of biomedical relevance in cases where MNPs should be used as nanocarriers for targeted drug delivery in tumor tissue derived from alveolar epithelial cells.