Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55454, United States.
Anal Chem. 2023 Aug 22;95(33):12419-12426. doi: 10.1021/acs.analchem.3c02074. Epub 2023 Aug 8.
Solid-contact ion-selective electrodes (SC-ISEs) in direct long-term contact with physiological samples must be biocompatible and resistant to biofouling, but most wearable SC-ISEs proposed to date contain plasticized poly(vinyl chloride) (PVC) membranes, which have poor biocompatibility. Silicones are a promising alternative to plasticized PVC because of their excellent biocompatibility, but little work has been done to study the relationship between silicone composition and ISE performance. To address this, we prepared and tested K SC-ISEs with colloid-imprinted mesoporous (CIM) carbon as the solid contact and three different condensation-cured silicones: a custom silicone prepared in-house (), a commercial silicone (Dow 3140, ), and a commercial fluorosilicone (Dow 730, ). SC-ISEs prepared with each of these polymers and the ionophore valinomycin and added ionic sites exhibited Nernstian responses, excellent selectivities, and signal drifts as low as 3 μV/h in 1 mM KCl solution. All ISEs maintained Nernstian response slopes and had only very slightly worsened selectivities after 41 h exposure to porcine plasma (log values of -4.56, -4.58, and -4.49, to -4.04, -4.00, and -3.90 for , , and , respectively), confirming that these sensors retain the high selectivity that makes them suitable for use in physiological samples. When immersed in porcine plasma, the SC-ISEs exhibited emf drifts that were still fairly low but notably larger than when measurements were performed in pure water. Interestingly, despite the very similar structures of these matrix polymers, SC-ISEs prepared with showed lower drift in porcine blood plasma (-55 μV/h, over 41 h) compared to (-495 μV/h) or (-297 μV/h).
固体接触离子选择性电极（SC-ISE）与生理样品直接长期接触，必须具有生物相容性和抗生物污染性，但迄今为止提出的大多数可穿戴 SC-ISE 都包含增塑聚氯乙烯（PVC）膜，其生物相容性较差。硅酮是 PVC 的一种很有前途的替代品，因为它们具有出色的生物相容性，但很少有研究致力于研究硅酮组成与 ISE 性能之间的关系。为了解决这个问题，我们制备并测试了 K SC-ISE，其固体接触为胶体印迹介孔（CIM）碳，以及三种不同的缩合固化硅酮：一种内部制备的定制硅酮（）、一种商业硅酮（Dow 3140，）和一种商业氟硅酮（Dow 730，）。用这些聚合物和离子载体缬氨霉素制备的 SC-ISE 以及添加的离子位点表现出 Nernstian 响应，极好的选择性，在 1 mM KCl 溶液中的信号漂移低至 3 μV/h。所有 ISE 在 41 小时暴露于猪血浆后仍保持 Nernstian 响应斜率，仅略微降低选择性（log 值分别为-4.56、-4.58 和-4.49，至-4.04、-4.00 和-3.90，对于、和，分别），证实这些传感器保留了使其适用于生理样品的高选择性。当浸入猪血浆时，SC-ISE 的电动势漂移仍然相当低，但明显高于在纯水中进行测量时的漂移。有趣的是，尽管这些基质聚合物的结构非常相似，但与 （-495 μV/h）或 （-297 μV/h）相比，用 制备的 SC-ISE 在猪血浆中表现出较低的漂移（-55 μV/h，超过 41 h）。
