Multilayer Label Free Non-Faradic Electrochemical Impedance Immunosensor for Cortisol Detection

Abstract

Cortisol, a well-known psychological stress biomarker, produced by the hypothalamic-pituitary-adrenal system, tends to intensify with stressors. Prolonged overexpression of cortisol leads to chronic stress that causes disparities in the proper functioning of the human body. Thus, there is a huge demand for developing a rapid cortisol detection system. Several point-of-care diagnostic techniques are available for rapid cortisol detection, such as electrochemical sensing, which works on changes in the electrical properties due to the binding of an analyte with a biorecognition element. Researchers have used different electrochemical methodologies such as cyclic voltammetry (CV), chronoamperometry, and faradic electrochemical impedance spectroscopy (EIS) for the detection of cortisol, but usage of external redox active reagents, low sensitivity, limited dynamic range, and electrode fouling nature limits their use. Hence, we reported a label-free and non-invasive cortisol detection using non-faradic EIS. A novel multilayer immunosensor was fabricated on PEDOT: PSS coated ITO glass by functionalizing with cortisol antibodies. Specific and rapid detection of cortisol was measured by monitoring the change in impedance in a dynamic range from 50-200 ng/mL. We envision the developed immunosensor has the potential for new developments in stress monitoring, disease prognosis, and enable personalized care. HighlightsO_LINovel PEDOT: PSS based multilayer immunosensor for cortisol detection C_LIO_LIImpedance based label free detection of cortisol using non-faradic EIS C_LIO_LIPresentation of detailed multilayer immunosensor fabrication, experimental detection, and equivalent circuit model with working mechanism C_LIO_LICortisol detection in a dynamic range of 50-200 ng/mL C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/550009v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@16f486forg.highwire.dtl.DTLVardef@fc9b3aorg.highwire.dtl.DTLVardef@333cf1org.highwire.dtl.DTLVardef@1e608e2_HPS_FORMAT_FIGEXP M_FIG C_FIG