Redox luminescence switch based on Mn 2+ -doped NaYF 4 :Yb,Er upconversion nanorods.

An redox luminescence switch was developed for the sensing of glutathione (GSH), l-cysteine (Cys) or l-ascorbic acid (AA) based on redox reaction. The Mn2+ -doped NaYF4 :Yb,Er upconversion nanorods (UCNRs) with an emission peak located in the red region were synthesized. The luminescence intensity of the UCNRs could be quenched due to the Mn2+ could be oxidized to MnO2 by KMnO4 . Subsequently, when the AA, GSH or Cys was added into the MnO2 modified upconversion nanosystem, which could reduced MnO2 to Mn2+ and the luminescence intensity was recovered. The concentration ranges of the nanosystem are 0.500-3.375 mM (R2  = 0.99) for AA, 0.6250-11.88 mM (R2  = 0.99) for GSH and 0.6250-9.375 mM (R2  = 0.99) for Cys, respectively.