A Reversible Dual-Channel Near-Infrared Flavonoid Probe for in Vivo Tracking Glutathione Dynamics in Living Mice

Glutathione (GSH) plays a critical role in various biological processes maintaining oxidative homeostasis. However, current reversible probe fluorescence emission is usually in the visible region, making it difficult to monitor glutathione levels in deep tissues and in vivo. Here, we developed a reversible near-infrared fluorescence probe, Flav-N, for real-time tracking of GSH in cells and tissues, which undergoes fast and reversible Michael addition reactions with biothiols. This Flav-N probe showed a rapid and reversible response with GSH at a time of less than 5 s (k = 1286 M^–1S^–1, t_1/2 = 729 ms). Notably, the dynamic changes in the ratio of Flav-N emission intensity at 505 and 728 nm were able to provide real-time feedback on the fluctuation of GSH concentration. We demonstrated that Flav-N enables the performance of fast and reversible imaging of intracellular GSH changes. Importantly, in light of the near-infrared emission and rapid response ability, Flav-N was successfully applied to track GSH dynamics in living mice. This reversible near-infrared NIR probe realizes advances in deep insight into the function of endogenous GSH.