Antibody functionalized interdigitated μ-electrode (IDμE) based impedimetric cortisol biosensor

Abstract

This paper reports on an ultrasensitive, disposable, impedimetric biosensor for cortisol detection. C-Mab (a Cortisol specific monoclonal antibody) was covalently immobilized via amide bond on the surface of the interdigitated μ-electrodes (IDμEs) functionalized with dithiobis(succinimidyl propionate) (DTSP) self-assembled monolayer (SAM). After C-Mab binding, unreacted active groups of DTSP were blocked using ethanolamine (EA) and glycine (Gly) mixture. The disposable sensors were exposed to solutions with different cortisol concentrations and a label-free electrochemical impedance (EIS) technique was used to determine the cortisol concentration. EIS results confirm that the EA-Gly/C-Mab/DTSP/IDμE based biosensor exhibited the sensitivity of 2.855 kohms M⁻¹ and could accurately detect cortisol in the range of 1 pM to 10 nM in saliva. This work establishes the feasibility of using an impedance based biosensor as a disposable cortisol detector, capable of working with complex bodily fluids (e.g., saliva). The architecture enables the use of cortisol sensors at point-of-care.