Environmental Engineering and Science Program, Department of Chemical and Environmental Engineering (ChEE), University of Cincinnati, Cincinnati, Ohio 45221-0012, United States.
Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268-0001, United States.
Anal Chem. 2021 Jan 19;93(2):812-819. doi: 10.1021/acs.analchem.0c03269. Epub 2021 Jan 4.
Electrochemical impedance spectroscopy (EIS), an extremely sensitive analytical technique, is a widely used signal transduction method for the electrochemical detection of target analytes in a broad range of applications. The use of nucleic acids (aptamers) for sequence-specific or molecular detection in electrochemical biosensor development has been extensive, and the field continues to grow. Although nucleic acid-based sensors using EIS offer exceptional sensitivity, signal fidelity is often linked to the physical and chemical properties of the electrode-solution interface. Little emphasis has been placed on the stability of nucleic acid self-assembled monolayers (SAMs) over repeated voltammetric and impedimetric analyses. We have studied the stability and performance of electrochemical biosensors with mixed SAMs of varying length thiolated nucleic acids and short mercapto alcohols on gold surfaces under repeated electrochemical interrogation. This systematic study demonstrates that signal fidelity is linked to the stability of the SAM layer and nucleic acid structure and the packing density of the nucleic acid on the surface. A decrease in packing density and structural changes of nucleic acids significantly influence the signal change observed with EIS after routine voltammetric analysis. The goal of this article is to improve our understanding of the effect of multiple factors on EIS signal response and to optimize the experimental conditions for development of sensitive and reproducible sensors. Our data demonstrate a need for rigorous control experiments to ensure that the measured change in impedance is unequivocally a result of a specific interaction between the target analyte and nucleic recognition element.
电化学阻抗谱（EIS）是一种极其灵敏的分析技术，是一种广泛应用于电化学检测的信号转换方法，可用于广泛的应用领域中的目标分析物。核酸（适配体）在电化学生物传感器的开发中被广泛用于序列特异性或分子检测，该领域仍在不断发展。虽然基于核酸的传感器使用 EIS 提供了极高的灵敏度，但信号保真度通常与电极-溶液界面的物理和化学性质有关。核酸自组装单层（SAM）在反复伏安和阻抗分析中的稳定性很少受到关注。我们研究了在金表面上具有不同长度的硫醇化核酸和短巯基醇的混合 SAM 的电化学生物传感器的稳定性和性能，这些传感器在反复电化学询问下进行了研究。这项系统研究表明，信号保真度与 SAM 层和核酸结构的稳定性以及核酸在表面上的组装密度有关。核酸的组装密度降低和结构变化会显著影响常规伏安分析后通过 EIS 观察到的信号变化。本文的目的是提高我们对多个因素对 EIS 信号响应的影响的理解，并优化开发敏感和可重复传感器的实验条件。我们的数据表明，需要进行严格的对照实验，以确保测量的阻抗变化确实是目标分析物与核酸识别元件之间特定相互作用的结果。
