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A substantial understanding of nanoparticles recognition and uptake by biological cells and tissues is very important for reaching their fullest potential in biomedical research. In this work, we investigated the cell endocytosis of iron oxide nanoparticles by both normal breast epithelial cells (MCF10A) and cancer breast epithelial cells (MCF7) using a combination of atomic force microscope (AFM) and nearfield scanning optical microscopy (NSOM) without the need of fluorescent labeling. This hybrid AFM/NSOM imaging method is capable of simultaneous recording topographic and near-field optical images, which provide complementary information in both morphology and optical analyses on the cellular exterior and interior. The resolution of images was observed to be very close to the size of tip. For both cell types, the iron oxide nanoparticles without targeting agents were found to be actively uptaken by a vesicle-mediated transport via a two-step process: a first step of binding at the cell membrane, followed by an subsequent internalization step.