A FRET chemsensor based on graphene quantum dots for detecting and intracellular imaging of Hg²⁺

The detection of Hg(2+) has attracted considerable attention because of the serious health and environmental problems caused by it. Herein, a novel ratiometric fluorescent chemsensor (GQDs-SR) based on the fluorescence resonance energy transfer (FRET) process for detecting of Hg(2+) was designed and synthesized with rhodamine derivative covalently linked onto graphene quantum dots. In this sensor, the graphene quantum dots (GQDs) served as energy donor and the rhodamine derivative turned into an energy acceptor when encountered Hg(2+). The chemsensor exhibited high selectivity, low cytotoxicity, biocompatibility and good water solubility. The results of intracellular imaging experiment demonstrated that GQDs-SR was cell permeable and could be used for monitoring Hg(2+) in living cells, and it was also successfully applied to the detection of Hg(2+) in practical water samples.