Efficient analysis of a small number of cancer cells at the single-cell level using an electroactive double-well array

Analysis of the intracellular materials of a small number of cancer cells at the single-cell level is important to improve our understanding of cellular heterogeneity in rare cells. To analyze an extremely small number of cancer cells (less than hundreds of cells), an efficient system is required in order to analyze target cells with minimal sample loss. Here, we present a novel approach utilizing an advanced electroactive double-well array (EdWA) for on-chip analysis of a small number of cancer cells at the single-cell level with minimal loss of target cells. The EdWA consisted of cell-sized trap-wells for deterministic single-cell trapping using dielectrophoresis and high aspect ratio reaction-wells for confining the cell lysates extracted by lysing trapped single cells via electroporation. We demonstrated a highly efficient single-cell arraying (a cell capture efficiency of 96 +/- 3%) by trapping diluted human prostate cancer cells (PC3 cells). On-chip single-cell analysis was performed by measuring the intracellular beta-galactosidase (beta-gal) activity after lysing the trapped single cells inside a tightly enclosed EdWA in the presence of a fluorogenic enzyme substrate. The PC3 cells showed large cell-to-cell variations in beta-gal activity although they were cultured under the same conditions in a culture dish. This simple and effective system has great potential for high throughput single-cell analysis of rare cells.