Colorimetric and fluorescent detection of GSH with the assistance of CTAB micelles

Two water-soluble colorimetric and turn-on fluorescent probes STP1–2 were rationally designed and synthesized for selective recognition of GSH. Both probes are colorless 4-thioether-1,8-naphthalimide derivatives, which are almost non-fluorescent due to the photoinduced electron transfer from the fluorophore to the 4-nitrobenzene. Upon addition of GSH to STP1/STP2–CTAB solution, obvious spectral responses were observed: the absorption peak shifted from 345 nm to 390 nm companied with ∼90-fold fluorescence enhancement at 487 nm. A good linear relationship between the fluorescence intensity and GSH concentration was obtained, and the detection limit of GSH was estimated to be 8.40 × 10−8 mol L−1. The experimental results imply that both probes could be applied in fluorescent imaging of GSH within living cells and in the detection of mercapto-containing proteins as well.