Psychological stress caused by everyday life style contributes to health disparities experience by individuals. It affects many biomarkers, but cortisol “a steroid hormone” is known as a potential biomarker for psychological stress detection. Abnormal levels of cortisol, is indicative of conditions such as Cushing’s syndrome Addison’s disease, adrenal insufficiencies and more recently post-traumatic stress disorder (PTSD). Chromatographic techniques, which are traditionally used to detect cortisol, are a complex system requiring multistep extraction/purification. This limits its application for point-of-care (POC) detection of cortisol. However, electrochemical immunosensing of cortisol is a recent advancement towards POC application. This review highlights simple, low-cost, and label-free electrochemical immunosensing platforms which have been developed recently for sensitive and selective detection of cortisol in biofluids. Electrochemical detection is utilized for the detection of cortisol using Anti-Cortisol antibodies (Anti-Cab) covalently immobilized on nanostructures such as self-assembled monolayer (SAM), polymer composite, etc. for POC integration of sensors. The observed information can be used as prototype to understand behavioral changes in humans in case to case such as farmers, fire fighters, etc. Keeping the future directions and challenges in mind the focus of the BioMEMS and Microsystems Research Group at Florida International University is on development of POC devices for immunosensing, integration of these devices with microfluidics, cross validation with existing technologies, and analysis of real sample.

No abstract

Conventional monoclonal and polyclonal antibodies are sensitive to changes in environmental factors such as temperature, pH, humidity, etc. This limits the current cost-effective and portable electrochemical immunosensors in harsh environments. Using Ricin Chain-A, a naturally occurring toxin, as a model analyte we report fabrication of a thermally stable electrochemical immunosensor. Single-domain antibodies (sdAb) or nanobodies have been employed as recognition elements for direct detection of Ricin at temperatures great than 4°C. Immunosensor fabricated using the conventional Ricin monoclonal and polyclonal antibodies have also been demonstrated for comparison. In the case of sdAb immunosensor, Ricin was detected in a linear range of 1log(fg/mL)-1log(μg/mL) with a sensitivity of 0.07μA/log(g/mL)/cm(2) using cyclic voltammetry. The fabricated miniaturized sensors have demonstrated higher shelf life and stability at temperatures up to 40°C. Therefore these electrochemical sensors can be integrated as a part of a portable device for point-of-care immunosensing.

No abstract

No abstract