Measuring Aptamer Affinity with Kinexa

Aptamers are nucleic acid or peptide molecules selected to have a high affinity and specificity for their substrates, very often in the sub-nanomolar range. Consequently, precise and reliable determination of their binding constant to the targets using techniques traditionally based on real-time monitoring is extremely challenging. To alleviate these roadblocks, we investigated the usefulness of the Kinetics Exclusion Assay (KinExA) technology to assess the equilibrium when high-affinity aptamers are employed. Although this technology was specifically developed for characterization of antibody-antigen interactions down to the femtomolar range, we adapted it for routine measurements of interactions that employ DNA aptamers