A novel electrochemical conducting polymer sensor for the rapid, selective and sensitive detection of biothiols

Abstract

Biological thiols (biothiols) in cells and bodily fluids are intrinsically linked to the functioning of important enzymes, deficiency of which can lead to a wide range of physiological and pathological conditions. Therefore, biothiol analysis is crucial for monitoring health and diseases in humans. Herein, we present the synthesis of a novel conducting polymer, poly(EDOT-thioacetate-co-EDOT) and its use in the development of an electrochemical detection platform for biological thiols, exemplified by detection of glutathione (GSH). The detection principle is based on electrochemical conversion of the thioacetate moieties on the conducting polymer to thiols which can form disulfide bonds with GSH present via electrochemical oxidation. Differential pulse voltammary (DPV) was used to generate the sensor readout where the signal corresponds to electrochemical oxidative coupling of GSH to the thiol moiety on the polymer. The sensor response of the optimised sensor has a proportional relationship with the logarithm of GSH concentrations between 1 μM and 600 μM, with a limit of detection of 0.32 μM. The optimised sensor also has an excellent selectivity regarding common bodily fluids-present interfering agents, such as uric acid, glucose, NaCl and KCl. The poly(EDOT-thioacetate-co-EDOT) also demonstrated the excellent re-usability and repeatability for detection of GSH up to the tested 10 cycles. The develop sensor platform is the first in its class and is an extremely promising method for the rapid, selective and sensitive detection of a range of important biological thiols using a simple electrochemical readout.