Nanostructured Electrochemical Cysteine Sensor Based on Carbon Nanotube Supported Ru, Pd, and Pt Catalysts

Abstract

At present, a voltammetric L-Cystein (Cys) sensor is developed based on carbon nanotube (MWCNT) supported Ru, Pd, and Pt monometallic catalyst modified glassy carbon electrodes (GCE). Ru/MWCNT, Pd/MWCNT, and Pt/MWCNT catalysts are prepared via sodium borohydride reduction method and characterized with advanced surface analytical techniques as inductively coupled plasma mass spectrometry (ICP-MS), N2 adsorptiondesorption, X-ray diffraction (XRD), and transission electron microscopy (TEM). Characterization results reveal that these catalysts are succesfully sythesized at desired metal loadings. For electrochemical studies, GCE is modified with Ru/MWCNT, Pd/MWCNT, and Pt/MWCNT catalysts to obtain a disposable, inexpensive, and sensitive sensor for Cys. The electrochemical behavior of the modified GCE is investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Ru/MWCNT modified GCE electrode exhibits best Cys electro-oxidation activity and thus, further electrochemical studies as sensitivity and limit of detection determination, intereference study, and real sample analysis are performed on Ru/MWCNT modified GCE electrode. The Cys sensor has a linear response within the range of 0-200 mu M with current sensitivity 0.3058 mu A/mu M (4307.05 mu A/mMcm2), and 0.353 lowest detection limit at (S/N = 3) signal to noise ratio. Interference studies reveal that Ru/MWCNT modified GCE electrode is not affected by D-glucose, uric acid, L-Tyrosine, L-Trytophane, H2O2, homocysteine, and glutathione as common interfering species. The