A Reversible Fluorescent Probe for Real‐Time Quantitative Monitoring of Cellular Glutathione

Abstract The ability to monitor and quantify glutathione (GSH) in live cells is essential in order to gain a detailed understanding of GSH‐related pathological events. However, owing to their irreversible response mechanisms, most existing fluorescent GSH probes are not suitable for this purpose. We have developed a ratiometric fluorescent probe (QG‐1) for quantitatively monitoring cellular GSH. The probe responds specifically and reversibility to GSH with an ideal dissociation constant (Kd) of 2.59 mm and a fast response time (t1/2=5.82 s). We also demonstrate that QG‐1 detection of GSH is feasible in a model protein system. QG‐1 was found to have extremely low cytotoxicity and was applied to determine the GSH concentration in live HeLa cells (5.40±0.87 mm).