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On-off-on relay fluorescence recognition of ferric and fluoride ions based on indicator displacement in living cells
摘要： A new boronic acid derivative functionalized with a 4-(3-(4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl)-1,2,4-oxadiazol-5-yl)phenyl (IOP) moiety was synthesized for use as a sequential “on-off-on”-type relay fluorescence probe for Fe3+ ions and F? ions with high selectivity and sensitivity under physiological conditions. The introduction of Fe3+ to IOP boronic acid (IOPBA) formed an Fe3+-IOPBA complex, which led to quenching of the blue fluorescence intensity at 458 nm. The lowest-energy conformation of IOPBA was theoretically predicted to adopt an extended structure, and the Fe3+ ion in the Fe3+-IOPBA complex was coordinated to two phenyl groups to form a p-complex. Upon addition of F? to the Fe3+-IOPBA complex, the original fluorescence was recovered due to formation of [FeF6]3?, resulting in “on-off-on”-type sensor behavior. IOPBA showed high selectivity towards Fe3+ among other cations. Moreover, the Fe3+-IOPBA complex showed specific selectivity towards F?, with other cations and anions not interfering with detection. Both sensing processes showed 1:1 stoichiometry with binding constants of 6.87 × 106 and 4.49 × 106 mol–1 L for Fe3+ with IOPBA and F? with Fe3+-IOPBA, respectively. The limits of detection for Fe3+ and F? were 10 and 1 nM, respectively. The proposed method was successfully applied in real water samples. Furthermore, the probe had low cytotoxicity and was successfully used as a bioimaging reagent to detect intracellular Fe3+ and F? in living HeLa cells.
关键词： Fluorescence imaging,On-off-on sensor,Probe for Fe3+ ions and F? ions,Living HeLa cells,Boronic acid derivative
更新于2025-11-21 11:08:12
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Carbon quantum dots derived by direct carbonization of carbonaceous microcrystals in mesophase pitch
摘要： Aggregation of the central aromatic ring system of asphaltene molecules due to π–π interaction can lead to the formation of carbon quantum dots (CQDs). However, to date, such a roadmap has not been demonstrated. Here, we present a simple approach to the synthesis of CQDs by direct carbonization of dispersed carbonaceous microcrystals in mesophase pitch. The size of the as-prepared CQDs is modulated by adjusting the nucleation temperature for mesophase formation. Due to the oxygen-free character, the CQDs exhibit excitation-independent fluorescent behavior with a quantum yield up to 87%. The CQDs were successfully applied to fluorescent detection of Fe3+ ions with good specificity and sensitivity. Our results not only provide a scalable production of CQDs at low cost, but also give valuable clues to understand the solidification of asphaltene at nanoscale.
关键词： Fe3+ ions,carbonization,mesophase pitch,fluorescent detection,carbon quantum dots
更新于2025-09-11 14:15:04