Wilson Lindsay R.Arendse Christopher J.Baker Priscilla G.L.2026-08-122026-08-122026Wilson, Lindsay & Arendse, Christopher & Baker, Priscilla. (2026). Unravelling redox driven electron transfer mechanisms within polythionine modified sensors, in the context of cortisol detection in vitro.. Results in Chemistry. 28. 103628. 10.1016/j.rechem.2026.103628.DOI: 10.1016/j.rechem.2026.103628https://hdl.handle.net/10566/25124Polythionine (PTH), a heterocyclic thiazine based conducting polymer known for its excellent redox activity, electrocatalytic properties, and biocompatibility. This study investigates the electrochemical behaviour of PTH on screen-printed carbon electrodes (SPCEs). Cyclic voltammetry, electrochemical impedance spectroscopy and spectroelectrochemistry were employed to characterize and assess electronic and redox processes. Polythionine modified SPCE exhibited pH dependent redox and capacitive behaviour according to spectroelectrochemistry and impedimetric phase angle maxima measurements as a function of applied voltage, with the lowest measured in acidic medium. Absorbance spectra are blue shifted for PTH bound SPCE in comparison to TH monomer. The difference in oxidation states allows PTH to be tunable for (bio)-chemical analysis, particularly useful for detection of critical hormones. Here, the platform was used to show usefulness for the electrochemical detection of cortisol, the stress hormone The sensing was done and achieved as a novel approach using polythionine modified SPCE. The assay exhibited a LOD of 45 μM, LOQ of 135 μM, dynamic linear range of 456 μM to 952 μM and sensitivity of 0.045 μA/μM. Though the polymer based chemical sensor performance metrics are not suitable for low cortisol concentrations, the assay remains a critical step towards proof-of-concept sensor systems for measuring critical biologically relevant small organic molecules in the micro molar range in vitro.enCortisolNon-enzymaticOxidation statespHPolythionineArticle