Clinical Implications of Cortisol and Bioanalytical Methods for Their Determination in Various Biological Matrices

Abstract

Advancement in lifestyle and exponential population growth have evoked competitiveness and struggle for survival, resulting in the elevated levels of physiological stress that notably shows correlation with the rising health disparities within the population. Sustained level of stress based on environmental factors, gender inequalities, competitiveness and post-traumatic stress disorders (PTSDs) triggers the hypothalamic-pituitary-adrenal axis (HPA) for signalling an abnormal release of cortisol from cortex region of the adrenal gland. Although several biomolecules and hormones are known to be influenced by physiological stress, examining cortisol (a steroid hormone) is observed to be one of the potential clinical strategies to assess the levels of the stress. Cortisol level varies regularly during day-night cycles that eventually regulates circadian rhythm. Free form of cortisol can provide accurate and precise determination of stress and is a biomarker for early diagnosis of disorder; hence real time estimation of cortisol can be beneficial to overcome many health issues. Chromatographic techniques are the conventional technology used for cortisol determination; however they possess several limitations such as bulky and complex system, multi-step lengthy and expensive extraction and purification process as well as high limit of detection leading to superficial information. Nowadays, multiple detection techniques have been discovered which consist of high sensitivity, require less or no sample preparation, miniaturization, rapid quantification and easy to use with minimal limitations. Electrochemical immunosensors and bioelectronics integrated with microfluidic platforms started gaining attention recently due to their non-invasive, quick responsive, highly sensitive and portable nature with wearable features. Considering the testing devices either reported in the literature or available for clinical practices, there still remains some improvements and scope to develop miniaturized and wearable point-of-care diagnostics that may exhibit increased sensitivity performance, simple design and rapid fabrication. This book chapter attempts to highlight information regarding cortisol detection sources in the body, the available sensing techniques and the diagnostic devices. In addition, we focus on recent advancements in the biosensing strategies for cortisol detection in particular using microfluidic technology. © Springer Nature Singapore Pte Ltd. 2021.