Highly selective detection of glutathione using a NIP/Cu2+ complex fluorescent probe

A novel fluorescent compound, 4-(trimethyl ammonium chloride)acetamide-2-(1H-naphtho[2,3-d]imidazol-2-yl)phenol (TMACA-NIP), was synthesized and used as a fluorescent probe for detecting glutathione reduced (GSH). The new NIP-based probe exhibited high fluorescence in water, which was quenched during the presence of copper (II) due to the complexation between TMACA-NIP and Cu2+. But after adding GSH into the TMACA-NIP and Cu2+ system, the fluorescence of TMACA-NIP was recovered because the binding force between GSH and Cu2+ is stronger than that between TMACA-NIP and Cu2+, which destroys the equilibrium between NIP and copper (II) ions and releases the fluorescence probe of TMACA-NIP. This three-component competing system of NIP/Cu2+/GSH can be used to detect GSH simply and rapidly.