Electrical detection of molecular surface receptor binding events in breast cancer cells

B.C. King, F. Khosravi, S.N. Rai, G. Kloecker, B. Panchapakesan
University of Louisville, US

Keywords: EpCAM, IGF1R, nanotube, breast cancer, diagnostic device

Summary:

Detection of circulating tumor cells (CTCs) from patient blood samples offers a desirable alternative to invasive tissue biopsies for screening of malignant carcinomas. CTCs are known to overexpress surface receptors, and these receptors provide an avenue for their detection. We have developed carbon nanotube (CNT) thin film devices to specifically detect these receptors in intact cells. The CNT sidewalls are functionalized with antibodies specific to Epithelial Cell Adhesion Molecule (EpCAM), a marker overexpressed by breast and other carcinomas. Specific binding of EpCAM to anti-EpCAM antibodies causes a change in the local charge environment of the CNT surface which produces a characteristic electrical signal. Two cell lines were tested in the device: MCF7, which overexpresses EpCAM, and MCF10A, a non-tumorigenic line which does not. MCF7 cells caused significant changes in the electrical conductance of the devices due to specific binding and associated charge environment change near the CNT sidewalls. Introduction of MCF10A display a different profile due to purely nonspecific interactions. The profile of specific vs. nonspecific interaction signatures using carbon based devices will guide development of this diagnostic tool towards clinical sample volumes with variety of markers.