Macromolecular Therapeutics

Selection of aptamers in vitro.

A library of nucleic acid aptamers is created by the SELEX method. The initially crude library of synthetic oligonucleotides (colored geometries) is exposed to the target molecule (black) bound to a surface (prior to Step 1). Members of the library that do not recognize the target are not retained, whereas bound members are “selected” into a residual library (result of Step 1). The residual library is amplified by PCR (Step 2), and further rounds of selection refine the aptamer pool (Step 3), ultimately purifying the optimal ligand (Step 4).