A simple turn on/off fluorescence approach based on dithizone‐capped ZnS quantum dots (ZnS@DZ QDs) with the help of lead ions as a fluorescent probe for the quantitative determination of quercetin is reported. The interaction of lead ions with dithizone led to the formation of a rigid structure on the surface of ZnS@DZ QDs and turned on the fluorescence intensity of the QDs. After addition of quercetin to this probe and interaction with lead ions, the fluorescence emission turned off. Concerning the quenching fluorescence intensity of ZnS@DZ QDs/Pb²⁺ QDs probe induced by the target, under the optimum conditions, the probe enabled detection of quercetin in the concentration range from 0.54 μM to 21.7 μM with a correlation coefficient of 0.993 and detection limit of 0.25 μM. The present probe was applied successfully to the determine quercetin as a nutritional biomarker in human serum and 24‐h urine samples.

中文翻译：

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基于双硫th封端的ZnS量子点的灵敏荧光探针，用于生物样品中槲皮素的测定。

报道了一种基于双硫/封端的ZnS量子点（ZnS @ DZ QDs）的简单打开/关闭荧光方法，该方法借助铅离子作为荧光探针定量测定槲皮素。铅离子与双硫zone的相互作用导致ZnS @ DZ量子点表面形成刚性结构，并开启了量子点的荧光强度。将槲皮素添加到该探针并与铅离子相互作用后，荧光发射关闭。关于目标诱导的ZnS @ DZ QDs / Pb ²⁺ QDs探针的猝灭荧光强度，在最佳条件下，该探针可检测浓度为0.54μM至21.7μM的槲皮素相关系数为0.993，检测限为0.25μM。本探针已成功用于测定槲皮素，作为人体血清和24小时尿液样品中的营养生物标志物。