Programming Aptamer–Protein Complexation Kinetics via Modulation of G-Quadruplex Secondary Structure

Aptamers have emerged as key receptors in the pursuit of universal biomolecular monitoring. However, while many aptamers possess excellent association rates, they tend to exhibit slow dissociation kinetics. While these slow off-rates are great for single-use applications, they pose a significant challenge for applications requiring continuous, repeated measurements where hysteresis complicates subsequent binding events. The G-quadruplex represents a common motif in many high-specificity aptamers and is composed of complexed guanine residues. Here, we present a method for modulating G-quadruplex aptamer binding kinetics through use of a polycytosine strand that can destabilize quadruplex structure and accelerate target release in a predictable manner. We demonstrate this phenomenon for several aptamer targets, including thrombin, interferon-gamma, and nucleolin, and highlight the ability of these modified aptamers to capture dynamic changes in analyte concentration on minute time scales.