A Bio-MEMS device for separation of breast cancer cells from peripheral whole blood

Abstract

This work demonstrates the application of Bio-Micro Electro Mechanical System (Bio-MEMS) technology for early breast cancer detection and diagnosis. Early breast cancer detection and diagnosis typically uses conventional mammogram screening followed by biopsy, which can be problematic since mammography can only detect highly calcified tumors greater than 1 cm in size. A micro-device was developed to identify and specifically collect tumor cells of low abundance (1 tumor cell among 107 normal blood cells) from circulating whole blood. By immobilizing anti-EpCAM (Epithelial Cell Adhesion Molecule) antibodies on polymer micro-channel walls by the chemical surface modification of PMMA, breast cancer cells from the cell line MCF-7, which over-express EpCAM on their surfaces, were caught by the strong binding affinity between the antibody and antigen. To validate the capture of the rare breast cancer cells, three fluorescence markers, each identified by a separate color, were used to reliably distinguish the cancer cells from blood cells. The cancer cells were defined by DAPI+ (blue), CD45- and the FITC-cell membrane linker+ (green). White blood cells, which will interfere in the detection of the cancer cells, were identified by DAPI+ (blue), CD45+ (red), and the FITC-cell membrane linker+ (green). Three EpCAM/Anti-EpCAM binding models were used to determine an optimal velocity, 2mm/sec, which should guarantee the binding of the maximum number of cells, a critical binding force, and a maximum throughput. At higher velocities, shear forces (> 0.48 dyne) will break existing bonds and prevent formation of new ones. This detection micro-device can be assembled with other lab-on-a-chip components for follow- up gene and protein marker analysis.