Observation of glutathione intra- and extracellular membrane with large Stokes shift probe modified by long alkyl chains.

A naphthylimide dye-based fluorescent probe (Nap-Mem-GSH) was synthesized for the detection of Glutathione inside and outside cell membranes. This probe carried a 2-Hydroxyquinoline fragment as a recognition site on top of a naphthalimide dye, which exhibits better selective and fluorimetric response toward Glutathione in natural media. The long alkyl chain confers a cell membrane targeting role to Nap-Mem-GSH. Therefore, the detection of intra-and extracellular glutathione inside and outside the cell membrane can be realized by Nap-Mem-GSH. Meanwhile, Nap-Mem-GSH not only has a large Stokes shift (160 nm), a low detection limit and a rapid response toward GSH, but also has the advantages of low cytotoxicity and good membrane permeability to living cells, and has been successfully applied to effectively detect and image intracellular glutathione by confocal fluorescence imaging.