Nitrobenzoxadiazole Ether-Based Near-Infrared Fluorescent Probe with Unexpected High Selectivity for H2S Imaging in Living Cells and Mice.

H2S is an important endogenous gasotransmitter, and its detection in living systems is of great significance. Especially, selective and sensitive near-infrared (NIR) fluorescent H2S probes with rapid response and large Stokes shift are highly desirable because of their superiority for in vivo detection. Probes with nitrobenzoxadiazole (NBD) ether as reaction sites have been well-explored recently to detect biothiols or H2S/biothiols simultaneously, rather than to detect H2S selectively. In this work, a new NBD ether-based NIR fluorescent probe was developed, which was unexpectedly found to show high selectivity for H2S over various other analytes including biothiols, making it practical for specific detection of H2S both in vitro and in vivo. Upon response to H2S, this probe showed rapid and significant turn-on NIR emission changes centered at 744 nm within 3 min, together with a remarkable large Stokes shift (166 nm) and high sensitivity (LOD: 26 nM). Moreover, imaging exogenous and endogenous H2S in living cells and rapid imaging of H2S in living mice with this probe was successfully applied with excellent performance.