Smartphone assisted fluorescent sensor for Fe3+and ascorbic acid determination based on off-on carbon dots probe

Iron ions (Fe3 +) and ascorbic acid (AA) are of great significance to living organisms. Herein, carbon dots (C-dots) -based "off-on " fluorescent probe was designed for Fe3 + and AA analysis. In presence of Fe3 +, the fluorescence of C-dots was immediately quenched, and the quenching mechanism was deduced to be inner filter effect (IFE). The fluorescent C-dot probe shows response to Fe3 + in range of 10-500 mu M with a limit of detection (LOD) of 0.9 mu M. Interestingly, when AA was introduced to the C-dots-Fe3 + system, the fluorescence of C-dots was significantly recovered, which could be ascribed to the oxidation-reduction reaction between Fe3 + and AA. Based "off-on " fluorescent C-dots probe, the linear range of 5-500 mu M was obtained with LOD of 0.4 mu M. Moreover, the AA -induced fluorescence enhancement can be recognized by smartphone, which greatly extends the application in resource-limited areas.