A green synthesis of highly fluorescent nitrogen-doped graphene quantum dots for the highly sensitive and selective detection of mercury(ii) ions and biothiols†
Abstract
A facile and environmentally friendly strategy to prepare nitrogen-doped graphene quantum dots (N-GQDs) with a high quantum yield of 28.10% was reported. The obtained N-GQDs exhibited strong blue fluorescence emission with the maximum emission and excitation at 450 nm and 355 nm, respectively. Taking advantage of the effective quenching effect of Hg2+ on N-GQDs, such N-GQDs were developed for the efficient and sensitive detection of Hg2+ with a relatively low detection limit of 0.032 μM. Based on the selective coordination of biothiols and Hg2+, the fluorescence of the N-GQD/Hg system was recovered with the addition of biothiols. This fluorescent “Off–On” process showed a sensitive response to biothiols with a detection limit of 0.036 μM for cysteine and 0.034 μM for glutathione. Most importantly, the N-GQD-based fluorescence method was successfully used to monitor Hg2+ in real water samples and biothiols in serum samples.