Plant-Derived Nitrogen-Doped Carbon Quantum Dots for Selective Cu2+ Detection and In Vivo Fluorescence Imaging

This study employed Cibotium barometz (L.) J. Sm. as a carbon source and carbamide as a nitrogen source to conduct a straightforward one-step hydrothermal synthesis of nitrogen-doped carbon quantum dots (N-CQDs). The N-CQDs were fully characterized in terms of their morphological features, chemical constituents, and optical behaviors. The synthesized N-CQDs exhibited the highest fluorescence intensity with excitation and emission wavelengths set at 305 nm and 382 nm, respectively. Notably, copper ions (Cu 2+ ) could induce obvious fluorescence quenching of the N-CQDs, endowing the system with high sensitivity and selectivity. The limit of detection (LOD) for Cu 2+ ions was determined to be 3.52 µM within the linear range of 1–10 µM. The fluorescence lifetime of N-CQDs was shortened from 3.38 ns to 3.27 ns after adding Cu 2+ . The analysis shows that the N-CQDs were selective and sensitive to Cu 2+ due to the static quenching mechanism. Furthermore, this method was applied to analyze the content of Cu 2+ in actual samples with satisfying results. More importantly, studies in zebrafish embryos and Arabidopsis thaliana verified the biocompatibility of N-CQDs at low concentrations, allowing efficient in vivo bioimaging, while Cu 2+ co-exposure caused fluorescence reduction. A facile strategy for synthesizing N-CQDs from natural plant-derived precursors is proposed in this work, revealing their great prospects as both fluorescent probes and bioimaging agents. Graphical The alternative text for this image may have been generated using AI.