Integrating Transcription Factors with Electrochemical Pendulum Bioanalysis for Hormone Detection

A challenge for direct biosensing of small molecule biomarkers is transducing the binding of low-molecular weight targets with large affinity receptors into measurable signals. Molecular pendulum bioanalysis enables highly sensitive detection but necessitates that target binding induces a significant change in hydrodynamic radius of the sensor construct. Herein, we demonstrate that receptors with allosteric binding properties can be integrated with molecular pendulum sensors to enable electrochemical detection of steroid hormone analytes. Transcription factors are immobilized on gold electrodes via DNA linkers, forming monolayers that transduce binding events into measurable current changes upon application of a positive voltage. In the presence of the target, allosteric dissociation of the receptor from the linker induces a faster faradaic current response. Using this approach, we employ a steroid-responsive transcription factor to achieve progesterone detection in simulated biofluids and spiked biological samples with relevant sensitivity. Our work establishes a framework for integrating transcription factors as recognition elements for direct electrochemical biosensors, expanding their compatibility to a broader range of analytes.