High-sensitivity detection of metastatic breast cancer cells via terahertz chemical microscopy using aptamers

We demonstrate high-sensitivity detection of metastatic breast cancer cells using terahertz (THz) chemical microscopy (TCM) with aptamers as ligands. For the aptamers, we use previously developed synthetic single stranded (ss) DNA aptamers mammaglobin B1 (MAMB1) and mammaglobin A2 (MAMA2) that bind to mammaglobin B and mammaglobin A proteins, respectively, which are overexpressed on the surface of MCF7 and MDA-MB-415 breast cancer cells. Each aptamer was immobilized on the surface of a sensing plate, and the amplitude of the THz signal was measured upon the binding of each aptamer to different number (10–10⁶) of its target breast cancer cells. A change in the THz amplitude was observed when MAMB1 and MAMA2 bind to MCF7 and MDA-MB-415, respectively. We find that this change was linear as a function of the log number of breast cancer cells used. No change in the THz amplitude was observed when the same number of normal breast cells (MCF 10A) were used. Moreover, MAMB1 and MAMA2 did not show binding to the counter breast cancer cells, indicating high selectivity. We have demonstrated that the TCM using aptamers as ligands has a limit of detection as small as 1 breast cancer cell in 100 μL of sample. Results described here indicate that the TCM could be a powerful tool to detect metastatic breast cancer cells.