NIR-Thiol dinitrobenzenesulfonate exhibits absorption and emission in the NIR region and is capable of imaging endogenously produced thiol in living cells and mice.

NIR-Thiol dinitrobenzenesulfonate is highly selective for small molecular weight biological thiols (Cys, Hcy, and GSH) over other biorelevant species such as Phe, Gly, Arg, Lys, Tyr, Leu, glucose, Ser, and Val. When incubated with living HeLa or Bel 7702 cells, it exhibits bright fluorescence. Notable features include NIR absorption and emission, rapid response, high sensitivity, excellent selectivity, good cell membrane permeability, and low cytotoxicity.

Varying doses (0, 20, 40, or 160 nmol) of NIR-Thiol dinitrobenzenesulfonate were administered intraperitoneally in mice, resulting in observable fluorescence intensity changes. Mice receiving the 20 nmol dose exhibited strong fluorescence, while control mice showed negligible fluorescence. Increasing the dosage to 40 or 160 nmol enhanced the fluorescence brightness significantly. Notably, a 700-fold increase in signal-to-noise contrast ratio was recorded for the 20 nmol dosage, which escalated to approximately 2900- and 7400-fold at 40 and 160 nmol dosages, respectively.