Fabrication of a nanostructured luteolin biosensor for simultaneous determination of levodopa in the presence of acetaminophen and tyramine: Application to the analysis of some real samples

The present study aims to investigate the preparation of new modified surfaces for electrodes based on direct electrochemical and electrocatalytic properties of luteolin (LU) immobilized on the functionalized multi-wall carbon nanotubes (fMWCNT) modified glassy carbon electrode (fMWCNT/GCE). The LU layer on fMWCNT/GCE was characterized by scanning electrochemical microscopy (SEM). The modified electrode was characterized as electrochemical sensor by different electrochemical techniques such as cyclic voltammetry and chornoamperommetry. The modified electrode showed a large electrocatalytic activity for oxidation of levodopa (LD), acetaminophen (AC) and tyramine (TR). Using differential pulse voltammetry (DPV), a sensitive simultaneous electrochemical oxidation of LD, AC and TR was attained: concentration at the ranges of 0.7-100.0 mu M, 1.0-90.0 mu M and 0.5-70.0 mu M, respectively and the detection limits for LD, AC and TR were sequentially 0.25 mu M, 0.52 mu M and 0.12 mu M. The developed LU biosensor exhibited good sensitivity, stability, and reproducibility for the determination of LD, AC and TR by DPV. The method was applied for the determination of LD, AC and TR in pharmaceutical formulations, dairy product and in human urine samples. (C) 2013 Elsevier Ltd. All rights reserved.