Polymer-Enhanced SELEX for the Identification of Aptamers with Higher Affinity

Systematic evolution of ligands by exponential enrichment (SELEX) is a powerful in vitro selection method for discovering aptamers from highly diverse random nucleic acid libraries. Through repeated rounds of selection, enrichment, and amplification, a small subset of sequences that form stable three-dimensional structures and bind specifically to a target can be progressively enriched. Despite these advantages, aptamer enrichment in SELEX can still be influenced by unexpected interactions with the selection matrix, leading to the enrichment of undesired sequences; this limitation may be addressed through the use of polymers. In this work, we report a refined, polymer-assisted SELEX strategy that broadens the range of sequences considered during selection, including those that may have been overlooked or discarded in conventional workflows. This refined workflow enabled us to identify aptamer candidates that bind a challenging target with strong affinity and high specificity. The selected sequences have potential utility in target-responsive sensing platforms and other diagnostic applications. We expect that this strategy can be extended to other targets and used to obtain aptamers with improved binding performance and selectivity.