Mitochondria-targeted NIR fluorescent probe for sensing Hg2+/HSO3− and its intracellular applications

Mercury and sulfur dioxide (SO2) are common pollutants in the ecological environment, which are important factors causing many diseases of organisms. The lack of appropriate analytical tools has limited the further understanding of the relationship between ionic mercury (Hg2+) and SO2. Herein, a bifunctional fluorescent probe LJ was designed and explored to simultaneously detect Hg2+ and SO2 via desulfurization reaction and Michael addition reaction, respectively. Probe LJ showed distinct fluorescence responses which a large near-infrared fluorescence enhancement towards Hg2+ at λem = 713 nm and a blue shift at λem = 450 nm towards SO2 without any spectral cross interferences. To the best of our knowledge, this is the first fluorescent probe with dual fluorescent emission channels to detect Hg2+ and SO2 with the detection limit of 187 nM and 354 nM, respectively. Moreover, cell fluorescent imaging experiments indicated that the probe was mitochondria targetable and provided evidence that SO2 could be used as an antidote to attenuate the toxicity of Hg2+ in living cells.