Improved electrocatalytic activity of Au@Fe₃O₄ magnetic nanoparticles for sensitive dopamine detection

Substantially, noble metals are important for the development of low-cost, sensitive, selective, superior performance, and portable electrochemical sensors. Herein, we describe gold (Au) nanoparticles (NPs) systematically decorated with magnetic Fe₃O₄ nanocomposites on the fabrication of sensitive dopamine sensor is described. Magnetic Au@Fe₃O₄ nanocomposites were prepared by reducing HAuCl₄ on the surfaces of Fe₃O₄ nanoparticles. The surface morphology of Au@Fe₃O₄ nanocomposites was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical behaviour of the modified electrode was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometric techniques, in which it was shown to be highly sensitive and selective towards DA. The amperometric detection of dopamine sensor, using this sensing element, exhibits a wide linear response of 0-0.8 μM with a low detection limit of 2.7 nM. In addition, the fabricated electrode showed an excellent stability and good reproducibility. The proposed analytical method was successfully applied to determine the concentration of dopamine in human urine samples and the unknown concentration of DA in human urine samples No. 1, 2 and 3 were determined as 0.056 ± 0.82 × 10^-3, 0.037 ± 0.87 × 10^-3 and 0.020 ± 0.94 × 10^-3 μM, respectively, with recoveries ranging from 97.2% to 103.4%, suggesting that the fabricated electrode can effectively detect DA in human urine samples.