Abstract
An electrochemically based antibody immobilization was used to perform environmentally and clinically relevant immunoassays for stress hormones biomarkers (cortisol and cortisone) using chemiluminescence (CL) detection. To achieve CL detection, the ferrocene tag on the antibodies was first oxidised, and this then acted as a catalyst for the luminol and hydrogen peroxide CL reaction. The conditions were optimised and measurements were made with an incubation time of 30 min. Using this approach limits of detection were obtained of 0.47 pg ml−1 and 0.34 pg ml−1 also R2 0.9912 and 0.9902 for cortisol and cortisone respectively with a linear concentration from 0 to 50 ng ml−1. The method was then applied to Zebrafish whole body and artificial saliva samples. For the Zebrafish sample recoveries of 91.0% and 90.0% were obtained with samples spiked with cortisol and cortisone, for artificial saliva the recoveries were 92.59% and 90.73% respectively. Interference studies showed only minor effects on the measurement of the analyte. A comparison between this procedure and the standard enzyme-linked immunosorbent assay (ELISA) procedure gave approximately the same R2 values.
Highlights
In this study, the biomarkers of interest are stress hormones, including cortisol and cortisone that belongs to glucocorticoids (GCs) family, which are secreted depending on environmental and behavioral triggers, and follow a circadian rhythm (CorbalánTutau et al 2014)
Characterization of ferrocene tagged anti-cortisol immobilized onto indium tin oxide (ITO) electrode surface To confirm the success of the immobilization process, cyclic voltammetry measurements were conducted for the modified ITO electrode surface without the antibody and with the tagged ferrocene antibody
An oxidation peak at + 0.25 V from Fig. 1 was seen for the ITO electrode with the tagged ferrocene antibody. This confirms the oxidation of the ferrocene to the ferrocenium cation on the ITO electrode surface with a reduction peak at + 0.25 V, as would expect no peak was seen for the blank ITO electrode
Summary
The biomarkers of interest are stress hormones, including cortisol and cortisone that belongs to glucocorticoids (GCs) family, which are secreted depending on environmental and behavioral triggers, and follow a circadian rhythm (all day cycle) (CorbalánTutau et al 2014). For healthcare monitoring which can be used for understanding human day-night stress hormones cycle secretion, simple low-cost measurement systems are Various approaches have been taken to determine stress hormones in biological samples These methods either require sophisticated equipment or involves procedures with rigorous control of the experimental conditions (Oßwald et al 2019; Luo et al 2019; Sturmer et al 2018; Miller et al 2013; Del Corral et al 2016; Gatti et al 2009; Yeh et al 2013; Barcellos et al 2007; IZAWA et al 2015; Ashley et al 2011; Weltring et al 2012; Russell et al 2014; Ammann et al 2014; Erickson et al 2012; Kartsova and Strel’nikova 2007; Gao et al 2015; Ceccato et al 2014; Saracino et al 2014; Sánchez-guijo et al 2014; Yeh et al 2015). The CL reaction of luminol with hydrogen peroxide system is frequently utilised with catalysts which include either enzymes such as horseradish peroxidase (Liu and Zhang 2015) or metal catalysts such as ferrocenecarboxaldehyde (Luo et al 2012) that contain iron
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
