AbstractA fluorometric assay for zinc ion is described that relies (a) on the use of an isothermal cycle to amplify the fluorescence signal, and (b) of magnetic beads (MBs) to completely remove unreacted DNA detection probes. Biotin and fluorophore-labeled substrate (Zn-Sub) strands acting as detection probes were first assembled on MBs. Next, Zn(II)-specific DNAzyme (Zn-Enz) strands were hybridized with the Zn-Sub strands. In the presence of Zn(II), the Zn-Sub strands are cleaved. This results in the release of the shorter DNA fragments (containing fluorescent label) and in the dissociation of Zn-Enz strands. The dissociated Zn-Enz strands then hybridize with the residual Zn-Sub strands and cleave them in a similar fashion. This leads to a target recycling amplification mechanism and in a cumulative signal amplification process. A strongly amplified signal is thus obtained in the presence of Zn(II). The use of MBs warrants that unreacted Zn-Sub strands can be magnetically separated from the solution. The method has a detection limit as low as 33 fM at a signal-to-noise ratio of 3 and a linear response in the 100 fM to 11 nM Zn(II) concentration range. It was applied to the determination of Zn(II) in spiked tap water and seawater samples, and the results compared well with data obtained by ICP-MS analysis. The method was also applied to the determination of Zn(II) in infant milk powder and breast milk. Graphical abstractMagnetic beads (MBs) carrying fluorescein-labeled substrate (Zn-Sub) strands were hybridized with Zn(II)-specific DNAzyme (Zn-Enz) and cleaved in the presence of Zn(II). After recycling, the unreacted Zn-Sub strands were removed with MBs and the released fluorescein tags are measured.

中文翻译：

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使用 DNAzyme 修饰的磁微珠荧光测定锌 (II)

摘要描述了锌离子的荧光测定法，它依赖于 (a) 使用等温循环来放大荧光信号，以及 (b) 磁珠 (MB) 以完全去除未反应的 DNA 检测探针。作为检测探针的生物素和荧光团标记的底物 (Zn-Sub) 链首先组装在 MB 上。接下来，将 Zn(II) 特异性 DNAzyme (Zn-Enz) 链与 Zn-Sub 链杂交。在 Zn(II) 存在下，Zn-Sub 链被切割。这导致更短的 DNA 片段（包含荧光标记）的释放和 Zn-Enz 链的解离。解离的 Zn-Enz 链然后与剩余的 Zn-Sub 链杂交并以类似的方式将它们切割。这导致目标循环放大机制和累积信号放大过程。因此在存在 Zn(II) 的情况下获得了强烈放大的信号。MB 的使用保证了未反应的 Zn-Sub 股线可以从溶液中磁性分离。该方法的检测限低至 33 fM，信噪比为 3，在 100 fM 至 11 nM Zn(II) 浓度范围内具有线性响应。将其应用于加标自来水和海水样品中 Zn(II) 的测定，结果与 ICP-MS 分析获得的数据进行了很好的比较。该方法还用于测定婴儿奶粉和母乳中的 Zn(II)。图形摘要携带荧光素标记底物 (Zn-Sub) 链的磁珠 (MB) 与 Zn(II) 特异性 DNAzyme (Zn-Enz) 杂交，并在 Zn(II) 存在下裂解。回收后，