A rapid strategy for the β-glycosidase (β-Gal) and Escherichia coli (E. coli) sensing is presented, which is based on selective recognition reactions of QDs using visualization/fluorescence (FL)/atomic fluorescence spectrometry (AFS)/inductively coupled plasma mass spectrometry (ICP-MS) multimode assay. CdTe QDs can selectively recognize Ag+ and Ag NPs with a cation exchange reaction (CER) where Ag+ triggers the release of Cd2+ and quenches the fluorescence signal of QDs. Taking advantage of the fact that β-Gal can hydrolyze 4-Aminophenyl β-D-galactopyranoside (PAPG) to produce p-aminophenol (PAP), which has the ability to reduce Ag+ to form Ag NPs. The β-Gal can be easily detected by visualization or FL in a turn-on manner. Furthermore, combining with the selective separation of Cd2+ by filter membrane, AFS and ICP-MS with higher sensitivity were used for the determination of the enzyme. Under optimized conditions, the system limits of detections (LODs) were 0.01 U/L, 0.03 mU/L, and 0.02 mU/L using FL, AFS, and ICP-MS as the detector, respectively. The relative standard deviations (RSDs, n = 7) for 0.1 U/L β-Gal were 2.2, 2.0, and 1.3% using FL/AFS/ICP-MS as the detector, respectively. And 0.1 U/L of β-Gal can be discriminated from the blank solution with the naked eye. In addition, given that the β-Gal can serve as an indicator of E. coli, we have successfully applied this strategy for the detection of E. coli with a LOD of 25 CFU/mL. Application of the method was demonstrated by analyzing human urine samples and milk samples for ultra-trace detection of E. coli. Graphical abstract The CVG-AFS/ICP-MS/visual/FL multimode β-Gal and E.coli detection via CER. The CVG-AFS/ICP-MS/visual/FL multimode β-Gal and E.coli detection via CER.

中文翻译：

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通过阳离子交换辅助信号放大多模式检测β-糖苷酶和病原菌

提出了一种用于 β-糖苷酶 (β-Gal) 和大肠杆菌 (E.coli) 传感的快速策略，该策略基于使用可视化/荧光 (FL)/原子荧光光谱 (AFS)/感应的 QD 的选择性识别反应耦合等离子体质谱 (ICP-MS) 多模式分析。CdTe QD 可以通过阳离子交换反应 (CER) 选择性识别 Ag+ 和 Ag NPs，其中 Ag+ 触发 Cd2+ 的释放并淬灭 QD 的荧光信号。利用β-Gal可以水解4-氨基苯基β-D-吡喃半乳糖苷（PAPG）产生对氨基苯酚（PAP）的事实，它具有还原Ag+形成Ag NPs的能力。β-Gal 可以通过可视化或 FL 以开启方式轻松检测到。此外，结合滤膜对Cd2+的选择性分离，酶的测定采用灵敏度较高的 AFS 和 ICP-MS。在优化条件下，使用 FL、AFS 和 ICP-MS 作为检测器的系统检测限 (LOD) 分别为 0.01 U/L、0.03 mU/L 和 0.02 mU/L。使用 FL/AFS/ICP-MS 作为检测器，0.1 U/L β-Gal 的相对标准偏差 (RSD，n = 7) 分别为 2.2、2.0 和 1.3%。0.1 U/L 的β-Gal 可以用肉眼从空白溶液中辨别出来。此外，鉴于 β-Gal 可以作为大肠杆菌的指标，我们已经成功地将这种策略应用于检测 LOD 为 25 CFU/mL 的大肠杆菌。通过分析人尿样品和牛奶样品对大肠杆菌进行超痕量检测，证明了该方法的应用。图形摘要 CVG-AFS/ICP-MS/visual/FL 多模式 β-Gal 和 E。通过 CER 检测大肠杆菌。通过 CER 进行 CVG-AFS/ICP-MS/visual/FL 多模式 β-Gal 和大肠杆菌检测。