An Electrochemical Biosensor Architecture Based on Protein Folding Supports Direct Real‐Time Measurements in Whole Blood

Abstract The ability to monitor drug and biomarker concentrations in the body with high frequency and in real time would revolutionize our understanding of biology and our capacity to personalize medicine. The few in vivo molecular sensors that currently exist, however, all rely on the specific chemical or enzymatic reactivity of their targets and thus are not generalizable. In response, we demonstrate here an electrochemical sensing architecture based on binding‐induced protein folding that is 1) independent of the reactivity of its targets, 2) reagentless, real‐time, and with a resolution of seconds, and 3) selective enough to deploy in undiluted bodily fluids. As a proof of principle, we use the SH3 domain from human Fyn kinase to build a sensor that discriminates between the protein's peptide targets and responds rapidly and quantitatively even when challenged in whole blood. The resulting sensor architecture could drastically expand the chemical space accessible to continuous, real‐time biosensors.