Aptamer-Enhanced Organic Electrolyte-Gated FET Biosensor for High-Specificity Detection of Cortisol

Organic field-effect transistor (FET) devices offer a low-cost manufacturing and simple integration of biorecognition molecules for biosensory applications. In electrolyte-gated organic FET (EGOFET) biosensors, a biofluid is directly integrated as the OFET gate dielectric for label-free bioelectronic sensing. The critical constraints of these devices are biofouling and the organic polymer's susceptibility to environmental effects. In this letter, we solve these issues by implementing a multilayered gate dielectric system in our low-cost OFET biosensor, encompassing the bioelectrolyte and an aptamer-enhanced top gate surface for the rapid high-sensitivity detection of cortisol in synthetic buffer solutions. To emphasize the crucial architectural and operational differences to EGOFETs, we have termed these devices as organic electrolyte-gated FET (OEGFETs). We also reported a numerical model that can be fitted to predict the behavior of the cortisol-specific OEGFET biosensors and highlighted the distinct advantages of our system, compared with the more traditional EGOFET sensors. The specificity of our cortisol biosensor is rigorously tested using two negative control biomolecules, i.e., progesterone and cortisone. Molecules that structurally resemble cortisol and like cortisols are present in detectable concentrations in the saliva. The detectable cortisol concentration range of our OEGFET biosensor is currently identified as 27.3 pM-27.3 μM.