AbstractA composite (Ag-g-CNQDs) was prepared from graphitic carbon nitride quantum dots and silver nanoparticles by water phase synthesis. Aided by metal-enhanced fluorescence, the composite exhibits excitation-dependent red emission with a peak at 600 nm with a quantum yield of 21%. If the composite is coated with polyethylenimine (PEI) to form the Ag-g-CNQD/PEI complexe, fluorescence is strongly reduced. Upon addition of heparin, the fluorescence of the system is enhanced because PEI has a higher affinity for heparin than Ag-g-CNQDs. The effect was used to design a fluorometric assay for heparin. The emission at 600 nm increases linearly in the 0.025 to 2.5 μM heparin concentration range, with a 8.2 nM limit of detection. Graphical abstractSchematic illustration for fabricating a composite consisting of silver nanoparticles and graphitic carbon nitride quantum dots (Ag-g-CNQDs). Its red fluorescence is weak in presence of polyethyleneimine but restored on addition of heparin. This forms the basis for a new method for heparin detection.

中文翻译：

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利用石墨氮化碳 (g-C3N4) 量子点的银纳米粒子增强荧光对肝素进行超灵敏检测

摘要 以石墨氮化碳量子点和银纳米粒子为原料，通过水相合成制备了复合材料（Ag-g-CNQDs）。在金属增强荧光的辅助下，该复合材料表现出依赖于激发的红色发射，峰值在 60​​0 nm，量子产率为 21%。如果复合材料涂有聚乙烯亚胺 (PEI) 以形成 Ag-g-CNQD/PEI 复合物，则荧光会大大降低。添加肝素后，系统的荧光增强，因为 PEI 对肝素的亲和力高于 Ag-g-CNQD。该效应用于设计肝素的荧光测定。600 nm 处的发射在 0.025 至 2.5 μM 肝素浓度范围内线性增加，检测限为 8.2 nM。图形摘要用于制造由银纳米颗粒和石墨氮化碳量子点 (Ag-g-CNQDs) 组成的复合材料的示意图。它的红色荧光在聚乙烯亚胺存在下较弱，但在加入肝素后恢复。这构成了肝素检测新方法的基础。