A novel peptide-based fluorescence chemosensor for selective imaging of hydrogen sulfide both in living cells and zebrafish

Hydrogen sulfide (H2S) plays an important role as a signaling compound (gasotransmitter) in living systems. However, the development of an efficient imaging chemosensor of H2S in live animals is a challenging field for chemists. Herein, a novel peptide-based fluorescence chemosensor L-Cu was designed and synthesized on the basis of the copper chelating with the peptide ligand (FITC-Ahx-Ser-Pro-Gly-His-NH2, L), and its H2S sensing ability has been evaluated both in living cells and zebrafish. The peptide backbone and Cu2+-removal sensing mechanism are used to deliver rapid response time, high sensitivity, and good biocompatibility. After a fast fluorescence quench by Cu2+ coordinated with L, the fluorescence of L is recovered by adding S2- to form insoluble copper sulfide in aqueous solution with a detection limit for hydrogen sulfide measured to be 31 nM. Furthermore, the fluorescence chemosensor L-Cu showed excellent cell permeation and low biotoxicity to realize the intracellular biosensing, L-Cu has also been applied to image hydrogen sulfide in live zebrafish larvae. We expect that this peptide-based fluorescence chemosensor L-Cu can be used to study H2S-related chemical biology in physiological and pathological events.