Nano-layered solid-contact potassium-selective electrodes (K+-ISEs) were explored as model ion-selective electrodes for their practical use in clinical analysis. The ultra-thin ISEs ought to be manufactured in a highly reproducible manner, potentially making them suitable for mass production. Thus, their development is pivotal towards miniaturised sensors with simplified conditioning/calibration protocols for point-of-care diagnostics. To study nano-layered ISEs, the ultra-thin nature of ISEs for the first time enabled to combine potentiometry-quartz crystal microbalance with dissipation (QCM-D) to obtain value-added information on the ISE potentiometric response regarding their physical state such as mass/thickness/viscoelastic properties/structural homogeneity. Specifically, the studies were focused on real-time observations of the ISE potentiometric response in relation to changes of their physicochemical properties during the ISE preparation (conditioning) and operation (including biofouling conditions) to identify the occurring processes that may accordingly be critical for potential instability of the ISEs, impeding their practical application. The K+-ISEs were prepared on a QCM-D gold sensor by electrodepositing poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) layer serving as an ion-to-electron transducer subsequently covered by a spin-coated poly(vinyl chloride) based K+-ion selective membrane (K+-ISM). The studies demonstrated that the performance of the nano-layered design of K+-ISEs is detrimentally affected by such processes as water layer formation accordingly causing the instability of the electrode potential. The changes in the ISE physical state such mass/viscoelastic properties associated with water layer formation and origin of the potential instability was already observed at the ISE conditioning stage. The potential instability of nano-layered ISEs limits their practical applicability, indicating the need of new solutions in designing ISEs, for instance, exploiting new water-resistant materials and modifying preparation protocols.

中文翻译：

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通过同时电位测定法和石英晶体微天平与耗散表征纳米层状固体接触离子选择性电极

纳米层状固体接触钾选择性电极 (K+-ISE) 作为模型离子选择性电极被探索用于临床分析中的实际应用。超薄 ISE 应该以高度可重复的方式制造，这可能使它们适合大规模生产。因此，它们的发展对于具有用于即时诊断的简化调节/校准协议的小型化传感器至关重要。为了研究纳米层状 ISE，ISE 的超薄特性首次能够将电位-石英晶体微天平与耗散 (QCM-D) 相结合，以获得有关 ISE 电位响应的增值信息，例如其物理状态，例如质量/厚度/粘弹性/结构均匀性。具体来说，这些研究的重点是在 ISE 制备（调节）和操作（包括生物污染条件）期间实时观察 ISE 电位响应与其物理化学性质的变化有关，以确定发生的过程，这些过程可能因此对潜在的不稳定性至关重要ISE，阻碍了它们的实际应用。K+-ISEs 是在 QCM-D 金传感器上通过电沉积聚（3,4-乙撑二氧噻吩）-聚（苯乙烯磺酸盐）层作为离子到电子传感器，随后被旋涂聚（氯乙烯) 基于 K+-离子选择性膜 (K+-ISM)。研究表明，K+-ISE 的纳米层状设计的性能受到水层形成等过程的不利影响，从而导致电极电位的不稳定。在 ISE 调节阶段已经观察到 ISE 物理状态的变化，例如与水层形成和潜在不稳定性起源相关的质量/粘弹性特性。纳米层状 ISE 的潜在不稳定性限制了它们的实际适用性，表明在设计 ISE 时需要新的解决方案，例如，开发新的防水材料和修改制备方案。在 ISE 调节阶段已经观察到 ISE 物理状态的变化，例如与水层形成和潜在不稳定性起源相关的质量/粘弹性特性。纳米层状 ISE 的潜在不稳定性限制了它们的实际适用性，表明在设计 ISE 时需要新的解决方案，例如，开发新的防水材料和修改制备方案。在 ISE 调节阶段已经观察到 ISE 物理状态的变化，例如与水层形成和潜在不稳定性起源相关的质量/粘弹性特性。纳米层状 ISE 的潜在不稳定性限制了它们的实际适用性，表明在设计 ISE 时需要新的解决方案，例如，开发新的防水材料和修改制备方案。