Selective and sensitive electrochemical detection of dopamine based on water-soluble porphyrin functionalized graphene nanocomposites

A biosensor, based on a water-soluble porphyrin-reduced graphene oxide (RGO) nanocomposite synthesized by simultaneous covalent and non-covalent strategies through aromatic pi-pi stacking and the formation of chemical bonds, was prepared for selective and sensitive detection of dopamine (DA). Compared with graphene or porphyrin alone, porphyrin-RGO nanocomposites exhibited unique advantages for the detection of DA in the presence of interfering substances such as uric acid (UA) and ascorbic acid (AA). The cyclic voltammetry (CV) curves indicated that the porphyrin-RGO modified glassy carbon electrode (GCE) had larger active area and better electrochemical catalytic activity which could attribute to the p-p stacking and the electrostatic attraction between positive charged DA and negative charged porphyrin-RGO, which can accelerate the electron transfer and weaken the oxidation of AA/UA on the porphyrin-RGO/GCE. Differential pulse voltammetry (DPV) was used for the quantitative detection of DA. The peak currents increased linearly with the increasing concentration of DA in the range of 1 x 10(-6) to 7 x 10(-5) M, and the limit of detection (LOD) (S/N = 3) was estimated to be 9.45 x 10(-9) M. More importantly, the biosensor exhibited good stability and reproducibility, and would provide a superior platform in the biological analysis.