Iridium oxide-modified reference screen-printed electrodes for point-of-care portable electrochemical cortisol detection

• Published in: Talanta (Oxford) 2024-12, Vol.280, p.126776, Article 126776
• Main Authors: Ji, Tong, Ye, Wen, Xiao, Weiyu, Dawson, Graham, Dong, Qiuchen, Gwenin, Christopher
• Format: Article
• Language: English
• Subjects: Biosensing Techniques - methods; Cortisol; Electrochemical; Electrochemical impedance spectrometry (EIS); Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Electrodes; Gold - chemistry; Humans; Hydrocortisone - analysis; Iridium - chemistry; Limit of Detection; Point-of-Care Systems; Screen-printed electrode; Stress
• ISSN: 0039-9140; 1873-3573; 1873-3573
• DOI: 10.1016/j.talanta.2024.126776

Cortisol is a well-known stress biomarker; this study focuses on using electrochemical immuno-sensing to measure the concentration of cortisol selectively and sensitively in artificial samples. Anti-cortisol antibodies have been immobilised on polycrystalline Au electrodes via strong covalent thiol bonds, fabricating an electrochemical bio-immunosensor for cortisol detection. IrOx was then anodically electrodeposited as a reference electrode on a commercial screen-printed electrode and electrochemical impedance spectrometry (EIS) studies were used to correlate the electrochemical response to cortisol concentration and the induced changes in charge transfer resistance (Rct). A linear relationship between the Rct and the logarithm of cortisol concentration was found in concentrations ranging from 1 ng/mL to 1 mg/mL with limit of detection at 11.85 pg/mL (32.69 pM). The modification of the reference electrode with iridium oxide has greatly improved the reproducibility of the screen-printed electrode. The sensing system can provide a reliable and sensitive detection approach for cortisol measurements. [Display omitted] •This manuscript has used an IrOx modified reference electrode for stable cortisol detection.•A covalent thiol bond for antibody attachment was used to reach selective and sensitive cortisol detection.•Electrochemical impedance spectrometry was employed for a linear relationship construction.