This work reports on a comparative analysis of electrical and optical measurements for structural characterization and for assessing signal transduction performance of a redox-labeled DNA-based sensing platform. We conducted complementary investigations employing conventional electrochemical techniques with electric current measurements in cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and confronted those results with optical measurements using surface plasmon waves while the redox assembly was undergoing similar electrochemical modulation as in the electrical CV and EIS measurements. The specific sensor configuration deployed here was composed of a methylene blue (MB)-modified single-stranded DNA (ssDNA) signaling probe and an unlabeled capture ssDNA probe that complements the signaling probe. Two types of signaling probes were employed: one with MB attached to the 3′ end, which positions the redox marker closer to the electrode surface upon hybridization with the capture probe, and the other with MB attached to the 5′ end, which places the redox marker farther from the electrode surface. For each molecular assembly and for each electrochemical modulation protocol, both the electrical and optical experimental data were quantitatively analyzed to determine the surface density of electro-active species and the rate of electron transfer between the redox marker and the electrode surface. Our experimental results highlight the consistency of the confronted methodologies and indicate that optical impedance spectroscopy utilizing electrochemically modulated surface plasmon waves, which is a transduction protocol immune from non-faradaic interferents that invariably are present in the electrical methodology, can provide a powerful route for developing a redox-labeled DNA-hybridization biosensing strategy.

中文翻译：

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电化学调制表面等离激元波，用于基于 DNA 的传感器的表征和询问


这项工作报告了用于结构表征和评估基于 DNA 的传感平台的信号转导性能的电学和光学测量的比较分析。我们采用传统的电化学技术进行了补充研究，并在循环伏安法 （CV） 和电化学阻抗谱 （EIS） 中进行了电流测量，并使用表面等离子体波进行光学测量来面对这些结果，而氧化还原组件正在经历与电气 CV 和 EIS 测量类似的电化学调制。此处部署的特定传感器配置由亚甲基蓝 （MB） 修饰的单链 DNA （ssDNA） 信号探针和补充信号探针的未标记捕获 ssDNA 探针组成。采用了两种类型的信号探针：一种是将 MB 连接到 3' 端，在与捕获探针杂交时将氧化还原标记物定位在更靠近电极表面的位置，另一种是将 MB 连接到5'端，将氧化还原标记物放置在离电极表面更远的地方。对于每个分子组装和每个电化学调制方案，定量分析电学和光学实验数据，以确定电活性物质的表面密度以及氧化还原标记物和电极表面之间的电子转移速率。 我们的实验结果突出了所面对方法的一致性，并表明利用电化学调制表面等离子体波的光阻抗谱，这是一种不受电学方法中始终存在的非法拉第干扰物免疫的转导方案，可以为开发氧化还原标记的 DNA 杂交生物传感策略提供一条强大的途径。