Pyrolytic preparation of gold nanoparticle-coated taro carbon and its application for the selective detection of dopamine

A highly selective and sensitive electrochemical method was developed for the detection of dopamine (DA), based on a gold nanoparticle (AuNP)-coated taro carbon (TC)-modified glassy carbon electrode (AuNP-TC/GCE). This novel AuNP-TC material was simply prepared by carrying out a pyrolysis of a composite material obtained by treatment of an acid-treated taro stem powder with HAuCl₄. Transmission electron microscopy (TEM), Raman spectroscopy, field-emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were employed to characterize the AuNP-TC material. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the modified electrode. The modified GCE exhibited a well-defined current response only toward the electrochemical oxidation of DA in a mixture solution of ascorbic acid (AA), DA, and uric acid (UA). This designed electrochemical sensor showed a linear response in the concentration range of 0.5 μM to 250 μM DA and a sensing limit (S/N = 3) of 0.25 μM was found. The sensor was also able to successfully detect DA in a dopamine hydrochloride injection (DAI). Moreover, the sensor exhibited excellent stability and reproducibility.