Nanosized materials have been proposed for a wide range of biomedical applications, given their unique characteristics. However, how these nanomaterials interact with cells and tissues, as well as how they bio-distribute in organisms, is still under investigation. Differences such as the nanoparticle size, shape, and surface chemistry affect the basic mechanisms of cellular uptake and responses, which, in turn, affects the nanoparticles' applicability for biomedical applications. Thus, it is vital to determine how a specific nanoparticle interacts with cells of interest before extensive in vivo applications are performed. Here, we delineate the uptake mechanism and localization of gold nanorods in SKBR-3 and MCF-7 breast cancer cell lines. Our results show both differences and similarities in the nanorod-cell interactions of the two cell lines. We accurately quantified the cellular uptake of gold nanorods in SKBR-3 and MCF-7 using inductively coupled plasma mass spectrometry (ICP-MS). We found that both cell types use macropinocytosis to internalize bare nanorods that aggregate and associate with the cell membrane. In addition, we were able to qualitatively track and show intracellular nanoparticle localization using transmission electron microscopy. The results of this study will be invaluable for the successful development of novel and "smart" nanodrugs based on gold nano-structural delivery vehicles, which heavily depend on their complex interactions with single cells.
Keywords: bare gold nanorods; breast cancer cell lines; cellular uptake; nanomaterials; nanotechnology.