Ultrasensitive determination of mercury ions using a glassy carbon electrode modified with nanocomposites consisting of conductive polymer and amino-functionalized graphene quantum dots

• Published in: Mikrochimica acta (1966) 2020-04, Vol.187 (4), p.210-210, Article 210
• Main Authors: Tian, Bowen, Kou, Yanxia, Jiang, Xiangmei, Lu, Jiajia, Xue, Yuanyuan, Wang, Meijuan, Tan, Liang
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Conducting polymers; Copper; Corrosion inhibitors; Electrodes; Endothelial cells; Glassy carbon; Graphene; Hydrogen peroxide; Hydroxyl radicals; Mercury (metal); Microengineering; Nanochemistry; Nanocomposites; Nanotechnology; Original Paper; Polymer industry; Polymers; Quantum dots
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-020-4191-1

A one-pot method based on cyclic voltammetric scan was used to fabricate a glassy carbon electrode modified with nanocomposites consisting of poly(thionine) and amino-functionalized graphene quantum dots (afGQDs). Under near-neutral conditions, the dye polymer was effectively oxidized by hydroxyl radicals (·OH) that were derived from the copper-catalyzed Fenton-like reaction, and the cathodic peak current on the modified electrode greatly increased. The reaction of Cu 2+ with thiourea (TU) and the generation of a complex, CuTU 2 + , led to the decrease of Cu 2+ /Cu + species, which inhibited the Fenton-like reaction and reduced the electrochemical response change. Due to a displacement reaction, the addition of Hg 2+ into the H 2 O 2 -Cu 2+ -TU system resulted in the release of cuprous ions that benefited the Fenton-like reaction. Under the following optimal conditions: 6 mg mL −1 afGQDs and the 25-cycle potential cycling for the fabrication of the modified electrode, pH 6.5, and the c Cu 2 + / c TU ratio of 1.0, the increasing extent of the cathodic peak current exhibited a good linear response to the logarithm of the Hg 2+ concentration in the range of 1 pM–1 μM with a detection limit of 0.6 pM. Mercury ions in a water sample were determined with good recovery, ranging from 97 to 103%. The investigation on the uptake of Hg 2+ into human vascular endothelial cells, HUVEC, shows that the cells incubated in the high-concentration glucose medium absorbed more mercury ions than HUVEC incubated in the normal medium. As a result, Hg 2+ could lead to the greater damage to the former. Graphical abstract