title: Fabrication of valine-functionalized graphene quantum dots and its use as a novel optical probe for sensitive and selective detection of Hg2.
abstract: The functionalization of graphene quantum dots has become a powerful method to modulate its chemical, electronic and optical properties for various applications. In the study, we reported a facile synthesis of valine-functionalized graphene quantum dots (Val-GQDs) and its use as a novel fluorescent probe for optical detection of Hg2+. Herein, Val-GQDs was synthesized by the thermal pyrolysis of citric acid and valine. The resulting Val-GQDs has an average size of 3nm and the edge of graphene sheets contains the rich of hydrophilic groups, leading to a high water-solubility. Compared to the GQDs prepared by thermal pyrolysis of citric acid, Val-GQDs exhibits a stronger fluorescence (>10-fold) and better photostability (>4-fold). Interestingly, the existence of valine moieties in the Val-GQDs results in a more sensitive fluorescent response to Hg2+. The fluorescent signal will linearly decrease with the increase of Hg2+concentration in the range from 0.8nM to 1μM with the correlation coefficient of 0.992. The detection limit is 0.4nM (S/N=3), which the sensitivity is >14-fold that of GQDs. The analytical method provides the prominent advantage of sensitivity, selectivity and stability. It has been successfully applied in the optical detection of Hg2+in real water samples. The study also provides a promising approach for the design and synthesis of functionalized GQDs to meet the needs of further applications in sensing and catalysis.
authors: School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
authors: Zhou
authors: Z
authors: Xiaoyan
authors: School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
authors: Li
authors: L
authors: Zhangyi
authors: School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, Wuxi 214122, China. Electronic address: zaijunli@263.net.
authors: Li
authors: L
authors: Zaijun
keywords: Detection; Fluorescent probe; Graphene quantum dots; Hg(2+); Water