We employed polypyrrole/graphene quantum dot (PPy/GQD) composites as a sensor for the simple and selective detection of catecholamine neurotransmitters (CNs), such as dopamine (DA), epinephrine (EP), norepinephrine (NE), which play vital roles in the peripheral and central nervous systems. The PPy/GQD composites showed strong fluorescence emission, which was significantly increased, by as much as greater than three times, compared to that of the pristine GQDs. In neutral solution, the CNs on the surface of the PPy/GQD composites were converted into a quinone structure, which triggered the fluorescence quenching of the PPy/GQD composites via a photo-induced electron transfer process. The CN concentration could be effectively monitored based on the quenching of the fluorescence signal of the PPy/GQDs. The quenching effect of DA is the fastest and most effective, followed by those of EP and NE, respectively, and the quenched fluorescence intensity of the PPy/GQDs was proportional to the concentration of DA (0.007–250 μM), EP (0.7–250 μM), and NE (5–500 μM). The present system was used for the quantification of CNs in human serum samples with acceptable results.

中文翻译：

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用于儿茶酚胺神经递质传感的增强型荧光石墨烯量子点的合成

我们采用聚吡咯/石墨烯量子点 (PPy/GQD) 复合材料作为传感器，用于简单和选择性地检测儿茶酚胺神经递质 (CN)，例如多巴胺 (DA)、肾上腺素 (EP)、去甲肾上腺素 (NE)，它们起着至关重要的作用在外周和中枢神经系统中。PPy/GQD 复合材料显示出强烈的荧光发射，与原始 GQD 相比，荧光发射显着增加了三倍以上。在中性溶液中，PPy/GQD 复合材料表面的 CNs 转化为醌结构，通过光诱导电子转移过程触发 PPy/GQD 复合材料的荧光猝灭。基于 PPy/GQDs 荧光信号的猝灭可以有效地监测 CN 浓度。DA 的猝灭效应最快和最有效，其次是 EP 和 NE，PPy/GQDs 的猝灭荧光强度与 DA (0.007-250 μM)、EP (0.7- 250 μM) 和 NE (5–500 μM)。本系统用于定量人血清样品中的 CNs，结果可接受。