Pentaethylenehexamine and d-penicillamine co-functionalized graphene quantum dots for fluorescent detection of mercury(II) and glutathione and bioimaging.

Pentaethylenehexamine and d-penicillamine co-functionalized graphene quantum dots (PEHA-GQD-DPA) was made via one two-step thermal pyrolysis. The resulting PEHA-GQD-DPA is composed of the graphene sheets with an average size of 3.16 nm and the rich of functional groups. It gives an ultra strong fluorescence emission with the fluorescent quantum yield of 90.91% and sensitive and selective optical response towards Hg. The fluorescence intensity linearly decreases with the increase of Hg in the range of 1.0 × 10-2 × 10 M with the detection limit of 4.6 × 10 M (S/N = 3). No species tested interfere with detection of Hg. The fluorescence quenched by Hg can be well recovered by glutathione. The fluorescence intensity linearly increases with the increase of glutathione in the range of 5 × 10-2.5 × 10 M with the detection limit of 1.7 × 10 M (S/N = 3). The PEHA-GQD-DPA as a fluorescence probe has been successfully applied in determination of Hg in natural water and glutathione in human serum and SW480 cell imaging.