Lysosome-targeted two-photon fluorescent probes for rapid detection of H2S in live cells
Two novel two-photon fluorescent probes (BHNP-DA and M2) were designed and synthesized,and show good selectivity and high sensitivity to H2S. The response of the probes to H2S in Tris–HCl buffer was rapid (50 s). The reaction mechanism of the probe BHNP-DA is based on hydrogen sulfide mediated tandem disulfide exchange, followed by a nucleophilic substitution–cyclization reaction and the fluorescence is turned on. The dual-nucleophilicity reaction of H2S could not be observed for the probe M2 as the fluorophore group is linked by an amide and the fluorescence is turned off. Furthermore, the probes were successfully applied for the fluorescence imaging of living MCF-7 cells. The colocalization experiments indicate that the probe BHNP-DA can effectively target lysosomes.