A colorimetric and fluorescent probe for detecting intracellular GSH

A new rapid and highly sensitive coumarin-based probe (probe 1) has been designed and synthesized for detecting intracellular GSH. Probe 1 was prepared from 4-methylumbelliferone using a 3-step procedure. It was converted into a latent fluorescence probe, which allowed it to achieve high sensitivity (LOD 122 nM) and fluorescence turn-on response (F/F0>15) toward GSH over other various natural amino acids in PBS buffer solution at pH 7.4. Owing to a specific Michael addition between thiols and the double bond of nitroolefin moiety, probe 1 displayed a high selectivity toward GSH. Afterwards, probe 1 was successfully used for fluorescence imaging of GSH in Hela and Hek-293a cells, and a rapid response was observed in the Hek-293a cells after incubating with probe 1 for 1 min. Simultaneously, a quantitative determination was achieved in Hela cells in the range of 8-48 μM. Specific fluorescence imaging of plants tissue was obtained for proving the permeability of probe 1. Finally, the viability was measured to be more than 80%, which shows probe 1 can serve as a rapid and biocompatible probe for GSH in cells.