Label-Free Solution-Based Kinetic Study of Aptamer–Small Molecule Interactions by Kinetic Capillary Electrophoresis with UV Detection Revealing How Kinetics Control Equilibrium

Here we demonstrate a label-free solution-based approach for studying the kinetics of biopolymer–small molecule interactions. The approach utilizes kinetic capillary electrophoresis (KCE) separation and UV light absorption detection of the unlabeled small molecule. In this proof-of-concept work, we applied KCE-UV to study kinetics of interaction between a small molecule and a DNA aptamer. From the kinetic analysis of a series of aptamers, we found that dissociation rather than binding controls the stability of the complex. Because of its label-free features and generic nature, KCE-UV promises to become a practical tool for challenging kinetic studies of biopolymer–small molecule interactions.