Microwave-assisted synthesis of carbon dots for "turn-on" fluorometric determination of Hg(II) via aggregation-induced emission.

A fluorescent probe is presented for sensitive determination of Hg(II). It is based on aggregation induced enhancement effect (AIEE) of carbon dots co-doped with nitrogen and sulfur (N,S-CDs). The N,S-CDs were prepared by a one-pot microwave-assisted method using glycerol as the reaction solvent, and cystine as the source for C, N and S. The resulting CDs are well soluble in water and have a turn-on fluorescence response to Hg(II). The incubation time and ratio of raw materials were optimized. Fluorescence, best measured at excitation/emission wavelengths of 325/385 nm, increases linearly in the 1-75 μM Hg(II) concentration range, and the detection limit is 0.5 μM. The method performed successfully when detecting Hg(II) in spiked tap and lake waters, with recoveries between 92 and 106%. Graphical abstract Schematic presentation of the aggregation induced enhancement of the fluorescence of carbon dots co-doped with nitrogen and sulfur after addition of Hg(II).