DNA Hydrogel-Interfaced Organic Electrochemical Transistor for the Investigation of Binding-Induced Conformational Change of Small Molecule Aptamers

Investigation of the small molecule-aptamer interaction is difficult, and it usually lacks information about the conformational change of aptamers that is important for their application. Here, we present the label-free investigation of small molecule-aptamer interactions using a modularized organic electrochemical transistor (OECT) platform. Leveraging the high sensitivity of the OECT, we measured the conformational change of the aptamer encountering its ligand. This platform consists of a simply fabricated OECT device and a DNA hydrogel-based bioreceptor module. Using this device, we investigated four DNA aptamers binding to cortisol (362.46 Da) and testosterone (288.4 Da). We demonstrated the correlation between the aptamer conformational change and the OECT response. We further calculated the apparent affinities of these aptamers based on the responses. This OECT-based platform also showed potential in binding kinetic measurements. We anticipate that the presented platform could advance the application of the newly identified aptamers as a convenient assay, providing multiple metrics for characterizing small molecule-aptamer interactions.