Turn-on fluorescence sensor for glutathione in aqueous solutions using carbon dots–MnO2 nanocomposites

A novel fluorescence sensor based on carbon dots–MnO 2 nanocomposites was fabricated successfully, which can detect glutathione (GSH) in aqueous solutions succinctly, rapidly and selectively. The carbon dots (CDs), which were synthesized by using organosilane as a coordinating solvent, had a highly luminescent quantum yield . The nanoflower-like MnO 2 had an enormous specific surface area, which could react with more CDs. Subsequently, CDs–MnO 2 nanocomposites were synthesized through a facile one-step method. As a result of fluorescence resonance energy transfer (FRET) from CDs to the MnO 2 , the fluorescence of CDs can be quenched by MnO 2 . However, when GSH was introduced into the system, the quenched fluorescence could be restored because MnO 2 was reduced to Mn 2+ by GSH, which led to the elimination of FRET. Compared with other electrolytes and biomolecules , we find that the chemical response of the CDs–MnO 2 nanocomposites exhibited good selectivity toward GSH. Under the optimal conditions, the proposed immunosensor was successfully performed with a linear range of 0.03–974.1   μmol   L −1 , with a detection limit of 0.015   μmol   L −1 . In addition, the proposed fluorescence sensor has several merits, such as low cost, good selectivity, great biocompatibility and chemical turn-on fluorescence response.