Abstract：
In this work, a sensitive ratiometric electrochemical biosensor for microRNA-155 (miRNA-155) detection is reported based on a hybridization chain reaction amplifying the electrochemical signal. The biosensor was fabricated using Au NPs as a modified material to assemble capture DNA labeled with ferrocene (Fc) molecules, and a DNA probe labeled with methylene blue (MB) was employed for the signal probe. In the presence of target miRNA-155, it can be dual hybridized with capture and signal probe, especially with signal probe to continuously produce long concatemers containing lots of MB molecules. The electrochemical signal of Fc was used for the internal signal, and the signal from MB was used as an indicator signal. As the concentration of miRNA-155 was altered, the internal reference signal of Fc remained constant, and only the indicator signal changed in a sensitive way. The change in the ratio (IMB/IFc) between the indicator signal of MB and internal reference signal of Fc can be used to monitor the concentration of miRNA-155. Under optimal conditions, the prepared ratiometric biosensor could detect miRNA-155 within a wide linear range from 100 fM to 100 nM with low detection limit of 33 fM (at S/N = 3). Moreover, the biosensor was evaluated with human serum samples, and satisfactory recoveries were obtained, indicating that the ratiometric biosensor can be applied to clinical sample analysis.
摘要：
在这项工作中,报道了一种用于microRNA-155（miRNA-155）检测的灵敏比例电化学生物传感器，该传感器基于放大电化学信号的杂交链反应。生物传感器是使用AuNP作为修饰材料制造的，以组装用二茂铁（Fc）分子标记的捕获DNA，并且用亚甲基蓝(MB)标记的DNA探针用作信号探针。在靶miRNA-155的存在下，它可以与捕获和信号探针双重杂交，特别是用信号探针连续产生含有大量MB分子的长串联体。Fc的电化学信号用于内部信号，来自MB的信号用作指示信号。随着miRNA-155浓度的改变,Fc的内部参考信号保持恒定，只有指标信号以敏感的方式改变。MB的指示信号与Fc的内部参考信号之间的比率(IMB/IFc)的变化可用于监测miRNA-155的浓度。在最优条件下,制备的比率生物传感器可以在100fM至100nM的宽线性范围内检测miRNA-155，低检测限为33fM（S/N=3）。此外，用人体血清样本评估生物传感器，并获得了令人满意的回收率，表明该比率生物传感器可应用于临床样品分析。
