Breast cancer is a major cause of cancer-associated deaths in the United States. It was estimated that 12% of women in the U.S. will develop invasive breast cancer in their lifetime. The human epidermal growth factor receptor (HER2/neu) is a growth-promoting protein that is overexpressed in 15–20% of breast cancers (HER2-positive breast cancer). HER2-positive breast cancer generally grows and spreads more quickly than other breast cancers, but it can be targeted therapeutically. Targeting drugs have been developed with a specific design to stop the growth and even the spread of cancer. These drugs include trastuzumab (Herceptin), pertuzumab (Perjeta), ado-trastuzumab emtansine (Kadcyla, or TDM-1), fam-trastuzumab deruxtecan, lapatinib, neratinib and tucatinib. However, the need for better targeted therapy and efficacy still exists. Nanotechnology could have major advantages in terms of detection, targeting, drug delivery, and destruction of cancer cells and tumors. Although a great deal of progress has been accomplished major challenges still need to be addressed. In this review, we examine the major areas of research in the area of nanotechnology and HER2-positive breast cancer.

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.