Disposable electrochemical sensor based on copper-electrodeposited screen-printed gold electrode and its application in sensing L-Cysteine

The development of reliable and cost-affordable electrochemical platform for rapid, sensitive, and selective detection of biological thiols has been sought after for various applications including clinical diagnosis and food monitoring. In this study, a novel disposable L-cysteine (CySH) sensor was developed based on screen-printed gold electrode (SPAuE) electrodeposited with copper. The constant potential electrodeposition was carried out at -0.4 V (versus an Ag pseudo-reference) for 480 s. The morphology and the crystal structure of electrodeposited copper were examined by scanning electron microscopy and X-ray diffraction. The analytical utility of the copper-modified SPAuE (Cu/SPAuE) was evaluated in an alkaline medium for the electrooxidation of CySH using cyclic voltammetry and amperometry techniques. The Cu/SPAuE exhibited fast response time (<5 s) and two linear ranges from 1 to 400 mu M (sensitivity of 0.028 mu A mu M-1) and 400-1800 mu M (sensitivity of 0.014 mu A mu M-1) with a detection limit (S/N = 3) of 0.21 mu M. The proposed CySH sensor also demonstrated high specificity in the presence of common interfering electroactive substances, such as sucrose, glucose, citric acid, urea, EDTA, oxalic acid, and uric acid. Furthermore, the proposed method has been successfully applied to the determination of CySH in human and rabbit blood serums without any sample pretreatment whereas the analytical recoveries were reasonably good, varying between 97.40 and 108.56% with satisfactory precision (RSD < 9%). (c) 2018 Elsevier Ltd. All rights reserved.