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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
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Electrochemical synthesis of phosphorus and sulfur co-doped graphene quantum dots as efficient electrochemiluminescent immunomarkers for monitoring okadaic acid
摘要： In this study, water-dispersed, uniform-sized phosphorus and sulfur co-doped graphene quantum dots (P, S-GQDs) were prepared by the one-step electrolysis of a graphite rod in an alkaline solution containing sodium phytate and sodium sulfide. Compared with GQDs and mono-doped GQDs (P-GQDs and S-GQDs), the P, S-GQDs dramatically improved the electrochemiluminescence (ECL) performance. Therefore, they were used as bright ECL signaling markers through conjugation with a monoclonal antibody against okadaic acid (anti-OA-MAb). Moreover, as an effective matrix for OA immobilization, the carboxylated multiwall carbon nanotubes-poly(diallyldimethylammonium) chloride-Au nanocluster (CMCNT-PDDA-AuNCs) composite promoted electron transfer and enlarged the surface area. Owing to the multiple amplifications, a competitive indirect ECL immunosensor for highly sensitive quantitation of OA has been developed. Under the optimized conditions, the 50% inhibitory concentration (IC50) of the immunosensor was 0.25 ng mL-1, and its linear range was 0.01–20 ng mL-1 with a low detection limit of 0.005 ng mL-1. Finally, the proposed ECL sensor was successfully utilized to detect OA contents in mussel samples. Therefore, this study provides new insights into the designation of ECL luminophores and expands application of co-doped GQDs in fabrication of ECL immunosensors for shellfish toxin determination.
关键词： immunosensor,electrolysis,okadaic acid,electrochemiluminescence,phosphorus and sulfur co-doped graphene quantum dots
更新于2025-09-12 10:27:22