Graphene Nanoribbons/Poly-Bromocresol Green Based Sensor for the Simultaneous Determination of 3,4-Dihydroxyphenylacetic Acid and 5-Hydroxyindoleacetic Acid

A novel voltammetric sensor based on graphene nanoribbons/poly-bromocresol green at the surface of pyrolytic graphite (pBG/GNRs/PG) has been prepared for the simultaneous determination of 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA); metabolites of neurotransmitters dopamine and serotonin. Graphene nanoribbons (GNRs) were fabricated by longitudinal unzipping of multiwall carbon nanotubes to form one-dimensional form of graphene strip. The characterization of GNRs and p-BG/GNRs/PG sensor has been done by using Raman spectroscopy, X-ray diffraction method, Electrochemical Impedance Spectroscopy, Field Emission Scanning Electron Microscopy, Cyclic Voltammetry and Square Wave Voltammetry. The sensor displayed excellent electrocatalytic effects toward the oxidation of DOPAC and 5-HIAA with a remarkable increment in the peak current and negative shift of the anodic peak potentials for both the analytes. The calibration curves were found to be linear in the wide concentration ranges of 0.05-180 mu M and 0.5-200 mu M with detection limits as 1.2 nM and 3 nM (n = 3) for DOPAC and 5-HIAA, respectively. The quantification limits were found (for n = 3) as 4.8 nM and 5.6 nM corresponding to DOPAC and 5-HIAA, respectively. The utility of the sensor as a diagnostic tool has been established by determining DOPAC and 5-HIAA in the human plasma and urine samples. (c) 2017 The Electrochemical Society. All rights reserved.