AIT Austrian Institute of Technology GmbH, 1210 Vienna, Austria.
AIT Austrian Institute of Technology GmbH, 1210 Vienna, Austria.
Biosens Bioelectron. 2019 Feb 15;127:25-30. doi: 10.1016/j.bios.2018.12.007. Epub 2018 Dec 13.
Gold electrodes have been used in a wide range of electrochemical biosensors because their functionalization process with thiols has been well described and, in general, they offer good chemical stability. However, one of the most commonly used redox-pairs in electrochemical impedance spectroscopy, Hexacyanoferrate (II)/(III), causes corrosion of the gold electrodes and consequently damages the surface modification. This leads to alterations of the sensing signals, and thus, renders the quantitative and sensitive detection of target molecules virtually impossible. To overcome this problem we introduced the in-situ generation of Hexaammineruthenium (II)/(III) as redox-pair during the impedimetric measurement by applying a DC-bias. This DC-bias was chosen in such a way that it supplied Hexaammineruthenium (II) in a suitable concentration at the electrode surface by reducing Hexaammineruthenium (III). We compared the stability of photolithographically fabricated thin-film and screen-printed gold electrodes in Hexacyanoferrate and Hexaammineruthenium solutions. Further, long-time characterization of the electrochemical properties with cyclic voltammetry and electrochemical impedance spectroscopy revealed that Hexaammineruthenium (II)/(III) was an excellent redox-pair for stable impedimetric measurements with gold electrodes. To demonstrate the suitability of Hexaammineruthenium for biosensing we applied it for the impedimetric detection of human-IgG. This biosensor exhibited a linear range from 11.3 ng/mL to 113 μg/mL, which is a suitable range for diagnostic applications.
金电极在各种电化学生物传感器中得到了广泛的应用，因为它们与硫醇的功能化过程已经得到了很好的描述，并且通常具有良好的化学稳定性。然而，电化学阻抗谱中最常用的氧化还原对之一，亚铁氰化铁(II)/(III)，会引起金电极的腐蚀，从而损坏表面修饰。这导致传感信号发生变化，从而使得目标分子的定量和敏感检测几乎不可能实现。为了解决这个问题，我们引入了在直流偏压下原位生成六氨合钌(II)/(III)作为氧化还原对的方法。选择这种直流偏压的方式是为了通过还原六氨合钌(III)在电极表面以合适的浓度提供六氨合钌(II)。我们比较了光刻制造的薄膜和丝网印刷的金电极在亚铁氰化铁和六氨合钌溶液中的稳定性。此外，通过循环伏安法和电化学阻抗谱对电化学性质进行长时间的表征，结果表明六氨合钌(II)/(III)是金电极稳定阻抗测量的理想氧化还原对。为了证明六氨合钌在生物传感中的适用性，我们将其用于人免疫球蛋白的阻抗检测。该生物传感器的线性范围为 11.3ng/mL 至 113μg/mL，适用于诊断应用。
