Screening of aptamers specific to colorectal cancer cells and stem cells by utilizing On-chip Cell-SELEX.

Colorectal cancer (CRC) is the most frequently diagnosed cancer around the world, causing about 700,000 deaths every year. It is clear now that a small fraction of CRC, named colorectal cancer stem cells (CSCs) exhibiting self-renewal and extensive proliferative activities, are hard to be eradicated. Unfortunately, highly specific biomarkers for colorectal CSC (CR-CSCs) are lacking that prohibits the development of effective therapeutic strategies. This study designed and manufactured a novel microfluidic system capable of performing a fully automated cell-based, systematic evolution of ligands by exponential enrichment (SELEX) process. Eight CR-CSC/CRC-specific aptamers were successfully selected using the microfluidic chip. Three of the aptamers showed high affinities towards their respective target cells with a dissociation constant of 27.4, 28.5 and 12.3 nM, which are comparable to that of antibodies.