A novel electrochemical sensor for selective determination of theophylline in pharmaceutical formulations

摘要

Theophylline (TPN) is a medication commonly used in treatment of chronic asthma disorder. However, it is associated with a number of known troublesome side effects, hence, the need to monitor its concentration levels in pharmaceutical formulations. In this work, a nanocomposite based on ZnONPs - MWCNTs - Cyt c (zinc oxide nanoparticles - multiwalled carbon nanotubes - Cytochrome c) were used in the modification of a highly sensitive electrochemical sensor for quantification of TPN in pharmaceutical formulations. The synthesized ZnONPs, ZnONPs-MWCNTs and ZnONPs-MWCNTs-Cyt c were characterized using Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission electron microscopy (TEM), surface area analysis by Brunauer-Emmett-Teller (BET) and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry was employed to study electro-catalytic properties of ZnONPs-MWCNTs-Cyt c-GCE towards oxidation of TPN. The dependence of peak currents and potentials on scan rates and pH were also investigated and the working parameters were optimized. Remarkably, ZnONPs-MWCNTs-Cyt c-GCE exhibited improved anodic peak currents as compared to ZnONPs-MWCNTs-GCE, MWCNTs-GCE and bare GCE for 0.1 M TPN at 1.0 V vs. Ag/AgCl. The linear range of the established electrochemical biosensor was from 0.4 to 15 mu M (R-2 = 0.9903) with detection limit of 0.0012 mu M, thus making it a better candidate for the detection of TPN in pharmaceutical formulation. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.