AbstractThe authors describe a colorimetric method for the determination of ultra-trace levels of uranyl ion (UO22+) in beverage and milk. It employs (a) DNAzyme-functionalized magnetic beads (MBs) for UO22+ recognition, (b) horseradish peroxidase (HRP)-assisted catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) for signal generation, and (c) rolling circle amplification (RCA) for sensitivity improvement. The employment of DNAzyme-functionalized MBs facilitates the separation and collection of analyte from sample matrix. This results in more convenient operation, better selectivity and more strong resistibility to sample matrix. The RCA strategy realizes one UO22+-to-massive HRP effect, which strongly improves the sensitivity. The method has outstanding advantages including high sensitivity, convenient operation, strong resistibility to complex matrix, and good selectivity. It can be used to detect as low as 20.0 pg·mL−1 (74 pmol·L−1) of UO22+ in milk and beverage by bare eye observation. Even lower concentrations (1.0 pg·mL−1 or 3.7 pmol·L−1) of UO22+ can be detected with the method via UV-visible spectrometry at 650 nm. The method was applied to analyze spiked samples and gave recoveries of 98 to 105% and RSDs of ±7% (n = 6). The visual detection limit is much lower than the maximum allowable level of UO22+ in drinking water as defined by the Environmental Protection Agency of USA. This indicated that the method meets the requirement of simple, rapid and on-site detection of ultra-trace UO22+ in milk and beverage. Graphical abstractA colorimetric assay was developed for the rapid and visual detection of trace UO22+ in beverage and milk by employing (a) DNAzyme-functionalized magnetic beads (MBs) for UO22+ recognition, (b) horseradish peroxidase-assisted catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine sulfate (TMB) for signal generation, and (c) DNA rolling circle amplification (RCA) reaction for signal amplification.

中文翻译：

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使用基于磁珠的 DNAzyme 识别结合滚环放大视觉检测超痕量铀离子

摘要作者描述了一种用于测定饮料和牛奶中超痕量铀酰离子 (UO22+) 的比色法。它采用 (a) DNAzyme 功能化磁珠 (MBs) 进行 UO22+ 识别，(b) 辣根过氧化物酶 (HRP) 辅助催化氧化 3,3',5,5'-四甲基联苯胺 (TMB) 以产生信号，以及（ c) 用于提高灵敏度的滚环扩增 (RCA)。使用 DNAzyme 功能化的 MB 有助于从样品基质中分离和收集分析物。这使得操作更方便，选择性更好，对样品基质的抵抗力更强。RCA策略实现了一种UO22+-to-massive HRP效应，大大提高了灵敏度。该方法具有灵敏度高、操作方便、对复杂基质的抵抗力强，选择性好。可用于通过肉眼观察检测牛奶和饮料中低至 20.0 pg·mL-1 (74 pmol·L-1) 的 UO22+。甚至更低浓度（1.0 pg·mL-1 或 3.7 pmol·L-1）的 UO22+ 也可以通过紫外-可见光谱法在 650 nm 处检测到。该方法用于分析加标样品，回收率为 98% 至 105%，RSD 为 ±7% (n = 6)。目视检测限远低于美国环境保护署定义的饮用水中 UO22+ 的最大允许水平。这表明该方法满足了对牛奶和饮料中超痕量UO22+进行简单、快速、现场检测的要求。