A visible and near-infrared, dual emission fluorescent probe based on thiol reactivity for selectively tracking mitochondrial glutathione in vitro.

The precise detection of endogenous biothiols such as Glutathione (GSH), Cysteine (Cys) and Homocysteine (HCy) is a long-standing human health concern. A dual-channel fluorescent probe (Cy-DC) composed of two fluorescence reporting units (dicyanomethylene-4H-pyran and cyanine) with ether linker for distinguishing different endogenous biothiols was designed and synthesized. Due to the two well-resolved emission bands, this probe possesses an outstanding capability for selectively sensing of endogenous GSH spatiotemporally and synchronously. Nevertheless, in the near infrared (NIR) channel (λex = 700 nm, λem = 810 nm), the probe can produce strong fluorescence only when it responds to GSH. Besides, the cells (L02 and U87) imaging, it also demonstrated that Cy-DC could successfully discriminate between GSH and Cys/Hcy with high sensitivity with the limit of detection (LOD) is 24 nM and 32 nM (3*SD/K). Particularly, the probe was applied in detecting solid tumor by the naked-eye and NIR imaging successfully, which revealed that the probe has promising prospects in clinical diagnosis applications.