Real-time tracking and selective visualization of exogenous and endogenous hydrogen sulfide by a near-infrared fluorescent probe

Rapid capture and selective visualization of hydrogen sulfide (H2S) in living systems has remained challenging. In this work, by employing ortho-aldehyde assisted thiolysis of 2,4-dinitrophenyl (DNP) ether approach and utilizing the dicyanomethylene-4H-chromene as the fluorophore, we developed a new fluorescent probe (E)-2-(2-(4-(2,4-dinitrophenoxy)-3-formylstyryl)-4H-chromen-4-ylidene) malo- nonitrile (2-CHO-OH) for this purpose with improved recognition performances. Probe 2-CHO-OH showed the advantage of quick reaction (8 min) with H2S, resulting in a strong near-infrared fluorescence emission (32-fold enhancement) and large Stokes shift (137 nm). More importantly, the probe could highly selectively detect H2S from other biological related species including cysteine, homocysteine and glutathione with distinct dual colorimetric and fluorescent signal changes. The detection limit of H2S was estimated as 8.3 x 10(-8) M, which was much lower than the intracellular concentration. Thanks to these unique features, 2-CHO-OH has been successfully applied for NIR fluorescence imaging of both the exogenous and endogenous H2S in living cells, demonstrating its value of practical application in biology. (C) 2017 Elsevier B.V. All rights reserved.