Figure 2.

Isolating aptamers by Selective Evolution of Ligands by Exponential Enrichment (SELEX) [22]. 1) Synthesis of a library of sequences for selection. 2, 3) Sequences that can bind a target of interest may be isolated from a library of sequences by affinity chromatography (as illustrated here) or by other selection methods, such as capillary electrophoresis, filtration and immunoprecipitation. 4) The active sequences may be amplified by PCR and 5) subjected to subsequent rounds of selection in order to enrich for the more active and robust sequences. For RNA aptamers, the sequences must be converted into complementary DNAs (cDNAs) prior to PCR amplification. Following PCR, in vitro transcription will have to be carried out in order to generate the RNA sequences before another round of selection can occur.