A novel flavonol-based fluorescent probe for rapid detection of Hg2+and its multi-functional applications

Mercury is a kind of heavy metal with bioaccumulation and is extremely toxic. The analysis and detection of mercury ions (Hg2+) are of great significance for environmental and human health. Hence, in this paper, we synthesized a novel fluorescent probe (TO-PCBM) based on flavonol as the fluorophore and thiocarbonate as the reaction site for turn-on monitoring of Hg2+. The probe TO-PCBM can detect Hg2+ sensitively, and possesses the excellent features of low detection limit (3.25 x 10-8 M), large Stokes shift (200 nm) and fast detection response (within 2 min). The unique sensing mechanism was attributed to the deprotection of thiocarbonate induced by Hg2+, leading to the strongly excited state intramolecular proton transfer emission of MHPCB. The detection mechanism was fully validated through ESI-MS, TLC and DFT calculations. Because of its high sensitivity, the probe TO-PCBM has a high recovery rate for trace mercury ions in real environmental water samples. Mean-while, due to its good biocompatibility and cell membrane permeability, the probe TO-PCBM can successfully monitor Hg2+ in fluorescence imaging of zebrafish and onion cells. Furthermore, the TO-PCBM-loaded test strip achieves simple and fast identification of Hg2+.