Dual sensing of glutathione and acidic pH values by using MnO2 nanosheets and 3-acetyl-7-hydroxy-2H-chromen-2-one as a fluorescent pH probe

A multifunctional nanoprobe is described for dual sensing of acidic pH values and glutathione (GSH) by combining the pH-responsive fluorescent probe 3-acetyl-7-hydroxy-2H-chromen-2-one (AHC) and MnO2 nanosheets. The fluorescence of the MnO2/AHC composite is weak due to an inner filter effect. If, however, the MnO2 nanosheets are reductively decomposed by GSH, the blue fluorescence of the pH probe AHC (with excitation/emission maximum at 417/456nm) will be restored. The MnO2 nanosheets also are decomposed by acidic pH values, and the fluorescence of AHC is decreased. According to absorbance and fluorescence signal changes, the pH and GSH induced responses can be easily distinguished. Thus, the nanoprobe can be used for logical analysis of acidic pH values and GSH. The nanoprobe works in the pH range from 4 to 7, and GSH can be determined in the concentration range from 0.5 to 200 mu M.