Figure 1.

Overview of the bivalent aptamer linker selection process. (A). Each molecule in the ssDNA library consists of two thrombin aptamers, Bock-15 and Tasset-29, joined by a 35-nt randomized linker region and flanked by two primer sites for PCR amplification. (B) The major steps of the microfluidic selection process are shown. Bivalent aptamers are captured by binding to thrombin-coated magnetic beads, and then washed within the MMS device to eliminate weakly and nonspecifically bound ssDNA. The resulting pool is then PCR amplified in a manner that enables rapid subsequent preparation of single-stranded molecules, which can then be subjected to further rounds of selection or directly characterized based on sequence and binding affinity.