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Off-on fluorescent switching of boron-doped carbon quantum dots for ultrasensitive sensing of catechol and glutathione
摘要： A signal-off-on probe of B-doped carbon quantum dot (B-CQD) is developed for ultrasensitive detection of catechol (CC) by fluorescence quenching and glutathione (GSH) by fluorescence recovering without any auxiliary of biomolecules or labeled materials. In this sensing system, the B-CQDs with a high quantum yield of 42% are prepared via a facile hydrothermal method with precursors of citric acid as C source and sodium tetraphenylborate as B source. The microstructure and fluorescence stability of the B-CQDs are investigated. Under the optimum conditions, the B-CQDs are highly sensitive for detecting CC with a linear range of 1-50 nM and a detection limit of 0.25 nM under a typical signal-to-noise ratio of 3 to 1 (S/N=3), and for sensing GSH with a linear range of 2-100 nM and a detection limit of 0.5 nM (S/N=3). Meanwhile, the developed B-CQDs show a good selectivity for sensing CC and GSH under high concentrations of interfering substances, such as biological thiols and amino acids. The B-CQDs are successfully applied to determination of CC in river water and GSH in human serum, where the recoveries are 103.3%-106.0% and 99.8%-106.3% for CC and GSH sensing, respectively. The signal-off-on mechanisms of the B-CQDs sensor are discussed.
关键词： Glutathione,B-doped carbon quantum dot,Sensitivity,Fluorescent sensing,Catechol
更新于2025-09-23 15:19:57
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Development of sulfur doped carbon quantum dots for highly selective and sensitive fluorescent detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples
摘要： Sulfur-doped carbon quantum dots (S-CQDs) with stable blue fluorescence were synthesized through a facile one-step hydrothermal method by using ascorbic acid and thioglycolic acid as carbon and sulfur sources. The prepared S-CQDs exhibited a sensitive and selective response to Fe3+ ions in comparison with Fe2+ and other metal ions, In the presence of adequate H2O2, Fe2+ was completely transformed to Fe3+ that is the determinable form of iron ions, and the difference in the change of the fluorescence intensity of S-CQDs before and after adding H2O2 was used for detection of Fe2+ ions, respectively. Under the optimum experimental conditions, the fluorescence intensity of S-CQDs gradually decreased with increasing of Fe3+ concentration ranging from 0 to 200 mM. Good linearity was achieved over the range of 0-200 mM. The detection limit of the developed method was 0.050 mM for Fe3+. The recoveries of Fe2+ spiked in real samples ranged from 98.2% to 112.4%. Finally, the proposed S-CQDs integrated with Fenton system was applied to the detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples, which presents potential applications in the speciation and determination of Fe2+ and Fe3+ ions in complex samples.
关键词： Fluorescence quenching,Iron supplement,Iron,Sulfur co-doped,Carbon quantum dot
更新于2025-09-19 17:13:59