A novel “off-on-off” fluorescent-nanoprobe based on B, N co-doped carbon dots and MnO2 nanosheets for sensitive detection of GSH and Ag+

In this study, a new “off-on-off” fluorescence strategy for detecting glutathione (GSH) and silver ions (Ag + ) is presented. The constructed nanoprobe is composed of B, N co-doped carbon dots (B, N-CDs) and manganese dioxide nanosheets (MnO 2 nanosheets), where MnO 2 nanosheets serve as a kind of efficient fluorescence quencher . The sensing mechanism of the system is based on the inner filter effect (IFE) and destruction-protection strategy. The assay strategy includes three processes: fluorescence quenching of B, N-CDs by MnO 2 nanosheets, the deconstruction of MnO 2 nanosheets by GSH, the combination between GSH and Ag + . The MnO 2 nanosheets are reduced to Mn 2+ because of the addition of GSH and restoring the fluorescence intensity of the system, while the formation of the complex between GSH and Ag + inhibit the reduction of MnO 2 nanosheets on account of the addition of Ag + , leading to the decrease in fluorescence of the probe. This strategy allows the quantitative detection of GSH and Ag + with detection limit of 0.32 μmol·L −1 and 0.24 μmol·L −1 , respectively. Moreover, this approach displays good sensitivity, selectivity and broad linear range, which could be broadly applicable for practical applications.