NCL-based mitochondrial-targeting fluorescent probe for the detection of Glutathione in living cells

Glutathione(GSH) plays a critical role in maintaining cellular redox homeostasis in biological system.Mitochondrion is a pivotal organelle for cellular aerobic respiration and its disorder is associated with impaired redox balance, leading to cell death. In this work, we designed and synthesized a non-invasive“off-on” mitochondrial-targeting fluorescent probe QZ for the detection of GSH in living cells. Based on the mechanism of native chemical ligation(NCL) and fluorescence resonance energy transfer(FRET), a rhodamine B derivative, QZ was prepared, by choosing aromatic thioester bond as the selective reaction site. QZ exhibited excellent detection capability for GSH over Cys and Hcy. Upon addition of GSH to QZ solution, a remarkably enhanced fluorescence was observed with a limit of detection of 2.98 μmol/L.Furthermore, QZ was found to possess the specific mitochondrial localization ability in cell imaging experiments. Moreover, with exogenous and endogenous stimulations, QZ could image GSH in living cells.