▎ 摘　　要

In this work, a simple and facile protocol for the synthesis of a cobalt-ferrite magnetic nanoparticle-reduced graphene oxide nanocomposite (CoFe2O4/RGO) was achieved using an in situ chemical co-precipitation method. The characteristics of the synthesized nanocomposite were carefully investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy and electrochemical technologies, respectively. The results reveal that the abundant CoFe2O4 nanoparticles are successfully formed with particle sizes in the range of 460-510 nm and uniformly anchored on the RGO nanosheets. Due to the imbedding of CoFe2O4 nanoparticles, the nanocomposite exhibits a larger surface area and superior electrocatalytic activity towards the oxidation of levodopa, which could be used as an efficient electrocatalyst for levodopa sensing. The parameters that influence the sensing property were investigated in detailed. Under the optimum conditions, the oxidation peak currents obtained by differential pulse voltammetry and chronoamperometry show linear responses for levodopa concentrations in the ranges of 0.02-45 mu M and 10-420 mu M respectively, and a low detection limit of 12 nM is achieved. Compared with those of the existing analogues reported for levodopa detection, the CoFe2O4/RGO-based sensor demonstrates outstanding properties such as high sensitivity, low detection limit and wide linear dynamic range. Finally, the practical analytical application of the developed sensor was assessed by the determination of levodopa in commercially available tablets and urine samples, and satisfactory recoveries were obtained in the range of 97.8-103.2%.