Electrochemical impedance spectroscopy (EIS) is a powerful technique for studying the interaction at electrode/solution interfaces. The adoption of EIS for obtaining analytical signals in biosensors based on aptamers is gaining popularity because of its advantageous characteristics for molecular recognition. Neuropeptide Y (NPY), the most abundant neuropeptide in the body, plays a crucial role with its stress-relieving properties. Quantitative measurement of NPY is imperative for understanding its role in these and other biological processes. Although aptamer-modified electrodes for NPY detection using EIS present a promising alternative, the correlation between the data obtained and the adsorption process on the electrodes is not fully understood. Various studies utilize the change in charge transfer resistance when employing an active redox label. In contrast, label-free measurement relies on changes in capacitance. To address these challenges, we focused on the interaction between aptamer-modified planar electrodes and their target, NPY. We proposed utilizing −ω*Z as the analytical signal, which facilitated the analysis of the adsorption process using an analogous Langmuir isotherm equation. This approach differs from implantable microelectrodes, which adhere to the Freundlich adsorption isotherm. Notably, our method obviates the need for a redox label and enables the detection of NPY at concentrations as low as 20 pg/mL. This methodology demonstrated exceptional selectivity, exhibiting a signal difference of over 20-to-1 against potential interfering molecules.

中文翻译：

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适配体修饰平面电极中神经肽 Y 的测量

电化学阻抗谱 (EIS) 是研究电极/溶液界面相互作用的强大技术。采用 EIS 在基于适体的生物传感器中获取分析信号因其具有分子识别的有利特性而越来越受欢迎。神经肽 Y (NPY) 是体内最丰富的神经肽，因其缓解压力的特性而发挥着至关重要的作用。 NPY 的定量测量对于了解其在这些和其他生物过程中的作用至关重要。尽管使用 EIS 进行 NPY 检测的适配体修饰电极是一种有前景的替代方案，但所获得的数据与电极上的吸附过程之间的相关性尚未完全了解。各种研究利用了使用活性氧化还原标记时电荷转移电阻的变化。相反，无标记测量依赖于电容的变化。为了应对这些挑战，我们重点关注适配体修饰的平面电极与其靶标 NPY 之间的相互作用。我们建议使用 -ω*Z 作为分析信号，这有助于使用类似的 Langmuir 等温方程分析吸附过程。这种方法不同于植入式微电极，后者遵循弗罗因德利希吸附等温线。值得注意的是，我们的方法不需要氧化还原标记，并且能够检测浓度低至 20 pg/mL 的 NPY。该方法表现出卓越的选择性，与潜在干扰分子的信号差异超过 20:1。