A nitrogen-doped carbon dots based fluorescent nanosensor for sensitive assay of Fe3+ ions in Dioscorea opposita Thunb

Trace detection of Fe3+ ions in complex matrices requires the development of highly sensitive sensors. Nitrogen-doped carbon dots (N-CDs) with admirable fluorescence efficiency, high photostability, and good biocompatibility have drawn special interest in fluorescent sensing of metal ions. In this work, a facile and economical microwave-assisted strategy was introduced for rapid synthesis of green fluorescence N-CDs, which were comprehensively characterized to display excitation-dependent fluorescent behavior with a high quantum yield of 18.1%, as well as good water solubility and high selectivity to Fe3+ ions. Then, a N-CDs based fluorescent “on-off” nanosensor was successfully fabricated for sensitive assay of Fe3+ ions. In the presence of Fe3+ ions, fluorescence of N-CDs was remarkably quenched due to the formation of N-CDs/Fe3+ complex through static quenching mechanism. Under the optimized synthetic and sensing conditions, the newly-developed nanosensor was free from other interfering metal ions for selective detection Fe3+ ions ranging from 1.0 to 80.0 μM with a low limit of detection of 1.0 μM, which are comparable with other methods. Practical application in Dioscorea opposita Thunb. samples exhibited fascinating recoveries of 98.5%−109.2% with relative standard deviations lower than 4.7%. The N-CDs based fluorescent nanosensor with simple construction, high selectivity and extremely sensitivity contributed a promising tool for rapid and environmental-friendly assay of Fe3+ions in a large number of actual samples.