A high–selectivity electrochemical sensor for ultra-trace lead (II) detection based on a nanocomposite consisting of nitrogen-doped graphene/gold nanoparticles functionalized with ETBD and Fe3O4@TiO2 core–shell nanoparticles

Abstract

A sensor made of Fe3O4@TiO2@NG@Au@ETBD was developed to specifically detect Pb2+ in a significantly toxic aqueous environment. Nitrogen–doped graphene (NG) was utilized as the substrate material of the sensor by a self–assembly method. The synergistic effect of the Fe3O4@TiO2 as well as the expanded activated surface and good electrical conductivity of the gold nanoparticles enhanced the detection of Pb2+. 2, 2′–((1E)–((4–((2–mercaptoethyl) thio) −1, 2–phenylene) bis (azanylylidene)) bis (methanylylidene)) diphenol (ETBD) was employed as the capture probe for the label–free detection. The electrical characteristics of the Fe3O4@TiO2@NG@Au@ETBD sensor were monitored to measure and investigate the performance of the sensor. Compared with conventional detection technologies and electrodes, this sensor enabled a wide linear range from 4×10−13mol/L to 2×10−8mol/L. Lower limits of detection and quantification for Pb2+, 7.5×10−13 and 2.5×10−12mol/L, respectively, were achieved. Furthermore, the Fe3O4@TiO2@NG@Au@ETBD sensor could distinguish Pb2+ from other metal ions despite the interfering metal ions with concentrations 103–fold higher than that of Pb2+. The proposed sensor could potentially be used in heavy–metal detection.