Evaluation of Magnetic Nanoparticles as Tools for Breast Cancer Cell Cytotoxicity

Chemotherapeutic or anti-neoplastic drugs kill rapidly dividing cancerous cells. However, dividing cell types such as hair follicle, intestinal, and blood cells are also killed generating undesirable off-target effects. Our long-term goal is to localize treatment to cancer cells in order to decrease side effects through the use of targeted magnetic nanoparticles (mNPs). mNPs can induce cell death by heating them (hyperthermia) and because they can deliver localized chemotherapeutic agents. Our working hypothesis is that mNPs bound to cells will cause hyperthermia and cell death when an alternating magnetic field (AMF) is applied. In order to identify mNPs that bind to and/or are endocytosed by cells, we tested the interaction between four fluorescently labeled iron oxide mNPs with differing surface characteristics and breast cancer cells. Cells were grown on cover slips and incubated with mNPs for 30 minutes. Confocal fluorescence microscopy of the cells was used to assess mNP cell binding and internalization on fixed cells co-labeled with fluorescent phalloidin to label cortical actin. Our results indicate that all four mNPs are effectively endocytosed by the cells and may therefore be appropriate for further development as localized therapeutic agents. Of the four mNP coatings, the cationic surface modification, Diethylamine-ethyl (DEAE), is endocytosed most consistently. We will confirm the localization of mNPs by co-labeling with endocytic markers. We are continuing these studies by testing the level of heating and cell death achieved by exposing cell bound mNPs to AMF.