Phenolic compounds, especially 4-nitrophenol (4-NP), and chromium (VI) are highly toxic environmental pollutants. Thus, it is significantly important to establish a rapid and sensitive sensor for 4-NP and Cr(VI) monitoring in environment. In this paper, a novel approach has been adopted where E. coli-derived CDs (CDs-WT) prepared by one step hydrothermal method previously and sensitized by ampicillin (turn-on) were used as fluorescence nanoprobe (CDs-WT-Amp) for 4-NP and Cr(VI) determination based on the inner filter effect quenching mechanism (turn-off). Then, the quenching fluorescence was reversed by addition of ampicillin (turn-on). The linear ranges of 4-NP and Cr(VI) detection were 0–50[Formula: see text][Formula: see text]M and 0–25[Formula: see text][Formula: see text]M, with the limits of detection 88.89[Formula: see text]nM and 64.75[Formula: see text]nM, respectively. The “turn-on-on-off-on” fluorescent nanosensor system was successfully used to determine Cr(VI) and 4-NP in water with satisfactory results. It shows that the “turn-on-off-on” nanoprobe has great promising potential for application to environmental pollutant detection.

中文翻译：

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基于内滤效应机制的细菌衍生碳点作为新型“开启-开启-关闭”传感器用于 Cr(VI) 和 4-硝基苯酚检测

酚类化合物，尤其是 4-硝基苯酚 (4-NP) 和铬 (VI) 是剧毒的环境污染物。因此，建立一种快速灵敏的传感器用于环境中的 4-NP 和 Cr(VI) 监测非常重要。在本文中，采用了一种新方法，其中将先前通过一步水热法制备并通过氨苄青霉素（开启）敏化的大肠杆菌衍生的CDs（CDs-WT）用作荧光纳米探针（CDs-WT-Amp）用于基于内部过滤效应淬灭机制（关闭）的 4-NP 和 Cr(VI) 测定。然后，通过添加氨苄青霉素（开启）来逆转淬灭荧光。4-NP和Cr(VI)检测的线性范围为0-50[公式：见正文][公式：见正文]M和0-25[公式：见正文][公式：见正文]M，其中检测限88.89[公式：见正文]nM和64。75[公式：见正文]nM，分别。“开启-开启-关闭-开启”荧光纳米传感器系统成功用于测定水中的Cr(VI)和4-NP，结果令人满意。这表明“开启-关闭-开启”纳米探针在环境污染物检测中具有巨大的应用潜力。