Efficient Synthesis of Highly Photo‐stable N‐doped Carbon Quantum Dots and their Applications in Detection and Cellular Imaging of Mercury Ions

In this work, the nitrogen doped carbon quantum dots (N‐CQDs) were synthesized by a simple microwave hydrothermal method using citric acid (carbon source) and urea (dopant) and optimized the preparation conditions by orthogonal tests. The synthesized N‐CQDs emitted a bright blue fluorescence with specific selectivity for Hg2+. The study revealed a static quenching mechanism of Hg2+ on the N‐CQDs. The N‐CQDs showed good linear correlation in the range of 0–120 μM for the detection of Hg2+ with a low detection limit of 22.50 nM. We also demonstrated the suitability of the N‐CQDs for the detection of Hg2+ in tap water and industrial wastewater with spiked recoveries of 97.56 %–103.58 %. In addition, the synthesized N‐CQDs with high fluorescence intensity, good optical stability and biocompatibility were successfully applied to fluorescent inks and imaging of Hela cells. This indicated that the synthesized N‐CQDs have promising applications in Hg2+ detection, bioimaging, and fluorescence anti‐counterfeiting. We have synthesized nitrogen‐doped carbon quantum dots (N‐CQDs) with high fluorescence quantum yield (62.67 %) by a simple and rapid microwave hydrothermal method. The synthesized N‐CQDs have excellent selectivity, good optical stability, and biocompatibility. The results indicate that the synthesized N‐CQDs have good application prospects in Hg2+ detection, bioimaging and fluorescence anti‐counterfeiting.