An automatic microfluidic system for rapid screening of cancer stem-like cell-specific aptamers

This study reports a microfluidic system which automatically performs the systematic evolution of ligands by exponential enrichment (SELEX) process for rapid screening of aptamers which are specific to cancer stem-like cells. The system utilizes magnetic bead-based techniques to select DNA aptamers and has several advantages including a rapid, automated screening process, and less consumption of cells and reagents. By integrating a microfluidic control module, a magnetic bead-based aptamer extraction module, and a temperature control module, the entire Cell-SELEX process can be performed in a shorter period of time. Compared with the traditional Cell-SELEX process, this microfluidic system is more efficient and consumes fewer sample volumes. It only takes approximately 3 days for an entire Cell-SELEX process with 15 screening runs, which is relatively faster than that of a traditional Cell-SELEX process (1 week for 15 rounds). The binding affinity of this resulting specific aptamer was measured by a flow cytometric analysis to have a dissociation constant (K (d)) of 15.32 nM. The capture rate for cancer stem-like cells using the specific aptamer-conjugated bead is better than that using Ber-EP4 antibody-conjugated bead. This microfluidic system may provide a powerful platform for the rapid screening of cell-specific aptamers.