Specific binding and magnetic concentration of CD8+ T-lymphocytes on electrowetting-on-dielectric platform.

In the quest to create a low-power portable lab-on-a-chip system, we demonstrate the specific binding and concentration of human CD8+ T-lymphocytes on an electrowetting-on-dielectric (EWOD)-based digital microfluidic platform using antibody-conjugated magnetic beads (MB-Abs). By using a small quantity of nonionic surfactant, we enable the human cell-based assays with selective magnetic binding on the EWOD device in an air environment. High binding efficiency (∼92%)of specific cells on MB-Abs is achieved due to the intimate contact between the cells and the magnetic beads (MBs) produced by the circulating flow within the small droplet. MBs have been used and cells manipulated in the droplets actuated by EWOD before; reported here is a cell assay of a clinical protocol on the EWOD device in air environment. The present technique can be further extended to capture other types of cells by suitable surface modification on the MBs.