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Impedimetric aptasensing using a symmetric randles circuit model
Electrochimica Acta ( IF 6.6 ) Pub Date : 2020-01-21 , DOI: 10.1016/j.electacta.2020.135750
Chih-Yu Lai , Wei-Chen Huang , Jui-Hong Weng , Lin-Chi Chen , Chia-Fu Chou , Pei-Kuen Wei

Electrochemical impedance spectroscopy (EIS) applied for aptasensing is being extensively studied for a variety of targets. Substitution of a symmetric electrode configuration for a conventional three-electrode setup on EIS aptasensing is becoming a trend due to its simple and favorable characteristics for biochip fabrication. However, a single Randles circuit is often used for impedance element parameter fitting in symmetric electrode aptasensing without rationalized basis of validity to date. In this work, an AC impedance model is derived for proving the validity of simplifying a symmetric Randles circuits in series into a single one and is examined with aptasensing applications. With the model, circuit parameter relationships can be quantified and correlated between symmetric and three-electrode configurations. The relationships are verified by comparing the fitted parameters obtained from standard gold electrodes (SGEs), microfabricated symmetric Au electrodes, and interdigitated array (IDA) Au electrode chips with different surface and detection conditions. The model is then found valid for different redox species composition (either Fe(CN)63− or Fe(CN)63−/4- is used) and for both blank and aptamer modified surfaces. From aptasensing of thrombin and tumor marker mucin 1 (MUC1), it is proved that the measured dissociation constants (KD: 129.4 nM for thrombin and 16.3 nM for MUC1) remain the same between a symmetric and three-electrode configuration, but the maximum change of charge transfer resistance (Bmax) is doubled in the symmetric one. This means that the symmetric configuration not only yields the same KD, but also results in a doubled binding signal for EIS aptasensing. In addition to the model derivation and experimental validation, specific EIS aptasensing of MUC1 using a symmetric electrode configuration is successfully demonstrated in this work.



中文翻译:

使用对称randles电路模型的阻抗适体

用于适应感的电化学阻抗谱(EIS)已针对各种目标进行了广泛的研究。由于其简单且有利于生物芯片制造的特性,在EIS适配上,将传统的三电极设置替换为对称电极配置已成为一种趋势。然而,单个Randles电路经常被用于对称电极适配中的阻抗元件参数拟合,而没有迄今为止合理的有效性基础。在这项工作中,导出了一个交流阻抗模型,以证明将串联的对称Randles电路简化为单个电路的有效性,并进行了适度的应用研究。使用该模型,可以量化电路参数关系,并在对称和三电极配置之间建立关联。通过比较从具有不同表面和检测条件的标准金电极(SGE),微型对称金电极和叉指阵列(IDA)金电极芯片获得的拟合参数,验证了这些关系。然后发现该模型对不同的氧化还原物质组成有效(Fe(CN)使用6 3−或Fe(CN)6 3− / 4-)和空白和适体修饰的表面。从凝血酶和肿瘤标志物粘蛋白1(MUC1)的适体性,证明了对称和三电极配置下测得的解离常数(凝血酶的K D:129.4 nM和MUC1的16.3 nM)保持相同,但最大值对称的电荷转移电阻(B max)的变化增加了一倍。这意味着对称配置不仅产生相同的K D,但也会导致EIS适体性的结合信号加倍。除了模型推导和实验验证之外,这项工作还成功证明了使用对称电极配置对MUC1进行的特定EIS适配。

更新日期:2020-01-21
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