1. Ultrasensitive determination of mercury ions using a glassy carbon electrode modified with nanocomposites consisting of conductive polymer and amino-functionalized graphene quantum dots.
- Author
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Tian, Bowen, Kou, Yanxia, Jiang, Xiangmei, Lu, Jiajia, Xue, Yuanyuan, Wang, Meijuan, and Tan, Liang
- Subjects
CARBON electrodes ,QUANTUM dots ,CONDUCTING polymers ,VASCULAR endothelial cells ,MERCURY ,SUBSTITUTION reactions ,THIOUREA - Abstract
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, CuTU2 + , led to the decrease of Cu2+ /Cu+ species, which inhibited the Fenton-like reaction and reduced the electrochemical response change. Due to a displacement reaction, the addition of Hg2+ into the H2 O2 -Cu2+ -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 Hg2+ 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 Hg2+ 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, Hg2+ could lead to the greater damage to the former. [ABSTRACT FROM AUTHOR]- Published
- 2020
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