Rational Design of a Ratiometric Fluorescent Probe Based on Arene-Metal-Ion Contact for Endogenous Hydrogen Sulfide Detection in Living Cells

摘要

We report the design and development of a fluorescent Cd-II ion complex that is capable of the ratiometric detection of H2S in living cells. This probe exploits the metal-ion-induced emission red shift resulting from direct contact between the aromatic ring of a fluorophore and a metal ion (i.e., arene-metal-ion or AM contact). The Cd-II complex displays a large emission blue shift upon interaction with H2S as the Cd-II-free ligand is released by the formation of cadmium sulfide. Screening of potential ligands and fluorophores led to the discovery of a pyronine-type probe, 6Cd(II), that generated a sensitive and rapid ratio value change upon interaction with H2S, without interference from the glutathione that is abundant in the cell. The membrane-impermeable 6Cd(II) was successfully translocated into live cells by using an oligo-arginine peptide and pyrenebutylate as carriers. As such, 6Cd(II) was successfully applied to the ratiometric detection of both exogenous and endogenous H2S produced by the enzymes in living cells, thus demonstrating the utility of 6Cd(II) in biological fluorescence analysis.