Highly sensitive electrochemical sensor based on flexible porous graphene for cortisol detection

This report presents the development of an electrochemical sensor for detecting cortisol in sweat, utilizing a flexible porous graphene electrode (fPGE). The fPGE was created using the laser-induced graphene technique on a polyimide substrate. The characterization of the porous graphene material was conducted through SEM and Raman spectroscopy. The graphene surface of the fPGE was modified with cortisol-aptamer with the assistance of linker molecules, PASE, to form the cortisol sensor. The electrochemical properties of the sensor were assessed using cyclic voltammetry technique (CV). Cortisol detection in the sensor was achieved indirectly via the reaction of the redox couple K4[Fe(CN)6]/K3[Fe(CN)6] on the surface of the cortisol aptamer-modified fPGE. As the concentration of cortisol in the solution increased, the corresponding current in the CV decreased. Under optimized conditions, the electrochemical cortisol sensor demonstrated a wide dynamic range of cortisol concentration from femtomolar (fM) to micromolar (µM) with a low limit of detection (LOD) of 100 fM.