Highly selective fluorescent carbon dots probe for mercury(II) based on thymine-mercury(II)-thymine structure

A novel thymine-functional fluorescent sensor was developed for Hg2+ detection with high sensitivity and selectivity. The synthesis of the fluorescent sensor took two steps (1) the synthesis of amine-functionalized carbon dots (CDs-PEI); and (2) the attaching of thymine moieties on to the surface of the CDs-PEI through EDC/NHS coupling chemistry to obtain the thymine-functional fluorescence carbon dots (CDs-Thy). The CDs-Thy were successfully applied to detect Hg2+ by quenching fluorescence with a rapid response through photoinduced electron transfer with the formation of T-Hg2+-T structures. The linear concentration range of Hg2+ is 0-1.0 mu mol L-1 and a limit of detection (LOD) as low as 3.5 x 10(-8) mol L-1 was obtained. Moreover, the CDs-Thy can resist interference from other metal ions and anions. The CDs-Thy were also used for the Hg2+ detection in water samples and the recoveries were from 90% to 104%. Due to the simplicity and effectiveness, it shows great promise as a potential sensing platform for Hg2+.