Abstract Herein, green-fluorescent N-doped carbon quantum dots (N-CQDs) with quantum yield of 30.6% were prepared via a simple bottom-up electrochemical (EC) method using the mixtures of pyrocatechol and ethylenediamine as both precursors and electrolytes. The ON-OFF fluorescence (FL) principle that the FL intensity of the N-CQDs was quenched in the presence of Fe3+ was further extended to the ON-OFF-ON and ON-OFF-ON-OFF ones for pyrophosphate anions (PPi) and alkaline phosphatase (ALP) detection, respectively, based on the specific competitive interaction of N-CQDs with Fe3+ and PPi and the hydrolysis of PPi in the presence ALP. Under the optimized conditions, limit of detection (LOD) of 1.2 μM and 0.5 μM were achieved for assays of Fe3+ and PPi, respectively. Meanwhile, measurable evaluation of ALP activity was reached in a wide range from 5 to 360 U/L with a LOD of 1.1 U/L. The as-proposed sensors showed many advantages including label free, rapid, simple, low-cost, high sensitive, which has great promising application potential in vivo and in vitro clinical diagnosis and will promote the application of EC derived carbon nanomaterials.

中文翻译：

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基于 Fe 3+ 介导的 ON-OFF-ON-OFF 荧光原理，电化学产生的绿色荧光 N 掺杂碳量子点用于轻松监测碱性磷酸酶活性

摘要 在此，以邻苯二酚和乙二胺的混合物作为前驱体和电解质，通过简单的自下而上电化学 (EC) 方法制备了绿色荧光 N 掺杂碳量子点 (N-CQD)，量子产率为 30.6%。N-CQDs的FL强度在Fe3+存在下被淬灭的ON-OFF荧光（FL）原理进一步扩展到焦磷酸盐阴离子（PPi）的ON-OFF-ON和ON-OFF-ON-OFF原理和碱性磷酸酶 (ALP) 检测，分别基于 N-CQD 与 Fe3+ 和 PPi 的特异性竞争相互作用以及 PPi 在 ALP 存在下的水解。在优化条件下，Fe3+ 和 PPi 的检测限 (LOD) 分别达到 1.2 μM 和 0.5 μM。同时，在 5 到 360 U/L 的广泛范围内达到了 ALP 活性的可测量评估，LOD 为 1.1 U/L。所提出的传感器显示出许多优点，包括无标记、快速、简单、低成本、高灵敏度，在体内和体外临床诊断中具有巨大的应用潜力，将促进EC衍生碳纳米材料的应用。