The fabrication of fluorescent sensor for Fe3+ detection and configurable logic gate operation based on N-doped carbon dots

Herein, fluorescent N-doped carbon dots (N-CDs) were obtained using hydrothermal treatment of polyethyleneimine and melamine . The N-CDs exhibit nanoscale structure, good water solubility, photostability and excellent fluorescence property with a high fluorescence quantum yield of 26 %. The as-prepared N-CDs were selected for the detection of Fe 3+ with a fluorescence “OFF-ON” strategy by the mechanism of internal filtration effect (IFE). A good linear relationship can be observed for the concentration of Fe 3+ from 0 to 500 μM, and the calculated detection limit (LOD) for Fe 3+ was 0.88 μM (3σ/slope). Meanwhile, the N-CDs based sensor can be utilized for tracing Fe 3+ in real water samples. In addition, the quenched fluorescence can be recovered with the treatment of l-cysteine, and thus can be designed for quantitative determination of l-cysteine with a fluorescent “ON-OFF-ON” switch. Moreover, a set of resettable, multireadout logic gate operations including OR and AND have been realized for the N-CDs.