Amine-modified magnetite (NH₂-Fe₃O₄)/reduced graphene oxide nanocomposite modified glassy carbon electrodes (NH₂-Fe₃O₄/RGO/GCEs) were developed for the sensitive detection of dopamine (DA). The NH₂-Fe₃O₄/RGO/GCEs were fabricated using a drop-casting method followed by an electrochemical reduction process. The surface morphologies, microstructure and chemical compositions of the NH₂-Fe₃O₄ nanoparticles (NPs), reduced graphene oxide (RGO) sheets and NH₂-Fe₃O₄/RGO nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The electrochemical behaviors of DA on the bare and modified GCEs were investigated in phosphate buffer solution (PBS) by cyclic voltammetry (CV). Compared with bare electrode and RGO/GCE, the oxidation peak current (ipa) on the NH₂-Fe₃O₄/RGO/GCE increase significantly, owing to the synergistic effect between NH₂-Fe₃O₄ NPs and RGO sheets. The oxidation peak currents (ipa) increase linearly with the concentrations of DA in the range of 1 × 10-8 mol/L - 1 × 10-7 mol/L, 1 × 10-7 mol/L - 1 × 10-6 mol/L and 1 × 10-6 mol/L - 1 × 10-5 mol/L. The detection limit is (4.0 ± 0.36) ×10-9 mol/L (S/N = 3). Moreover, the response peak currents of DA were hardly interfered with the coexistence of ascorbic acid (AA) and uric acid (UA). The proposed NH₂-Fe₃O₄/RGO/GCE is successfully applied to the detection of dopamine hydrochloride injections with satisfactory results. Together with low cost, facile operation, good selectivity and high sensitivity, the NH₂-Fe₃O₄/RGO/GCEs have tremendous prospects for the detection of DA in various real samples.
Keywords: NH2–Fe3O4 nanoparticles; dopamine; electrochemical oxidation; modified electrode; reduced graphene oxide.