Immunosensor with fluid control mechanism for salivary cortisol analysis

Abstract

The purpose of this research is to demonstrate a new design for a cortisol immunosensor for the noninvasive and quantitative analysis of salivary cortisol. We propose a cortisol immunosensor with a fluid control mechanism which has both a vertical flow and a lateral flow. The detected current resulting from a competitive reaction between the sample cortisol and a glucose oxidase (GOD)-labeled cortisol conjugate was found to be inversely related to the concentration of cortisol in the sample solution. A calibration curve using the relative detected current showed an R2 = 0.98 and CV = 14% for a range of standard cortisol solutions corresponding to the concentrations of native salivary cortisol (0.1 – 10 ng/ml). The measurement could be accomplished within 35 minutes and the cortisol immunosensor could be reused. These results show promise for realizing an on-site and easy-to-use biosensor for cortisol. Used for evaluation of human salivary cortisol levels, the cortisol immunosensor measurement corresponded closely with commercially available ELISA method (R2 = 0.92). Our results indicate the promise of the new cortisol immunosensor for noninvasive, point-of care measurement of human salivary cortisol levels.

Electrochemical lateral flow immunosensor for detection and quantification of dengue NS1 protein

“…Moreover, the architecture and sensitivity of AuNPs-based colorimetric immunoassay for HIgG has been successfully improved and achieved a detection limit of 60 ng/mL (Parolo et al 2013b). However, colorimetric AuNPs-based immunoassays coupled with the enzymatic reaction of horseradish peroxidase (HRP) have a limited lifetime and thus the performance of the biosensor itself unless enhancement techniques are incorporated for cortisol by integrating paper pad with screen-printed flat platinum electrodes (Yamaguchi et al 2013). …”

Point-of-Care Testing in the Time of P5 Medicine: A Preface

“…Research groups have been developing portable biosensors to allow for near ''real-time'' detection and quantification of stress-response biomarkers, including salivary α-amylase and cortisol. (16)(17)(18)(19) Executable algorithms and treatment decision trees inputted into the biosensor microprocessor would eventually be able to analyze patterns in salivary stress biomarkers to generate simple feedback that is readily accessible to even a non-specialist. Enabled by this "smart systems" technology, trauma care providers would be able to identify "at-risk" patients, conduct timely restorative interventions, or refer individuals for specialized mental health care, in addition to monitoring progress and response to therapy.…”

Electrochemical Sensing of Cortisol: A Recent Update

“…Self-assembled monolayer (SAM) [37], Au nanowires [38], Au-PANI nanocomposite [39], AgOAg-PANI nanocomposite [40], and Graphene [41] based electrochemical cortisol immunosensors have been developed. These immunosensors have been integrated with microfluidic systems for POC sensing [36,42]. This section gives an inclusive overview of the various electrochemical detection platforms integrated for quantification of cortisol.…”

“…The fabricated cortisol biosensor based on calorimetric protocol detects cortisol concentrations between 1 to 10 ng mL −1 within 25 min. Another SAM based cortisol immunosensor has been proposed by the same research group integrated with a fluid control mechanism which has both a vertical flow and a lateral flow [42]. A competitive reaction between the sample cortisol and GOD-labeled conjugate was found to be inversely related to the concentration of cortisol and can be detected electrochemically.…”