g-C3N4 nanosheets as on-off-on selective fluorescence biosensor to detect ascorbic acid via redox reaction

A novel fluorescence probe was built by using graphitic carbon nitride (g-C3N4) nanosheets. Fluorescence of the g-C3N4 nanosheet solution was effectively quenched by Fe3+ via photoinduced electron transfer (PET). Moreover, the linear detection range for Fe3+ was 0-43.33 nM with a limit of detection of 4 nM. Fluorescence recovery of g-C3N4 was observed upon addition of ascorbic acid (AA) to the g-C3N4 nanosheet-Fe3+ system, and the paramagnetic Fe3+ was reduced to diamagnetic Fe2+ by blocking PET. An on-off-on fluorescence response was observed through the oxidation-reduction between Fe3+ and AA. Furthermore, a wide linear detection range for AA was found in 0-26.67 nM. Thus, this system can play a dual role in the selective and sensitive detection of Fe3+ and AA in aqueous media via on-off-on fluorescence response. (C) 2018 Elsevier B.V. All rights reserved.