Reduced Graphene Oxide Non-covalent Functionalized with Zinc Tetra Phenyl Porphyrin Nanocomposite for Electrochemical Detection of Dopamine in Human Serum and Rat Brain Samples

We described the use of a nanocomposite consisting of reduced graphene oxide and zinc tetraphenylporphyrin (RGO/Zn-TPP) for electrochemical sensing of dopamine (DA). The surface of RGO was homogeneously functionalized with Zn-TPP via non-covalent π-π interaction. The nanocomposite was characterized by scanning electron microscopy, UV-Vis spectrometry, nuclear magnetic resonance spectroscopy and electrochemical impedance spectroscopy. The electroanalysis behavior of the nanocomposite was studied by cyclic voltammetry and amperometry. The excellent electrocatalytic activity is found for oxidation of DA, best at working voltage of 0.214 V (vs. Ag/AgCl) and linear response range of 0.04–238.8 μM. The sensitivity and detection limit were of 0.665 μA µM−1 cm−2 and 3 nM, respectrively. The electrode is well reproducible, stable, and represents a viable platform for the analysis of DA in DA injection, human serum and rat brain sample.