School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Ulsan 689-798, Republic of Korea.
Analyst. 2013 Mar 7;138(5):1370-8. doi: 10.1039/c2an36346a.
We describe a novel and simple mechanism for inducing ion concentration polarization (ICP) using a surface-patterned perm-selective nanoporous film like Nafion in single, open microchannels. Such a surface-patterned Nafion film can rapidly transport only cations from the anodic side to the cathodic side through the nanopore clusters so that it is possible to generate an ICP phenomenon near the Nafion film. In this work, we characterize transport phenomena and distributions of ion concentration under various electric fields near the Nafion film and show that single-channel based ICP (SC-ICP) is affected by Nafion film thicknesses, strengths of applied electric fields, and ionic strengths of buffer solutions. We also emphasize that SC-ICP devices have several advantages over previous dual-channel ICP (DC-ICP) devices: easy and simple fabrication processes, inherently leak-tight, simple experimental setup requiring only one pair of electrodes, stable and robust ICP induced rapidly, and low electrical resistances helping to avoid Joule heating, and membrane perm-selectivity breakdown but allowing as high bulk flow as an open, plain microchannel. As an example of applications, we demonstrate that SC-ICP devices not only have high potential in pre-concentrating proteins in massively parallel microchannels but also enable the concentration and lysis of bacterial cells simultaneously and continuously on a chip; therefore, proteins within the cells are extracted, separated from the concentrated cells and then pre-concentrated at a different location that is closer to the Nafion film. Hence, we believe that the SC-ICP devices have higher possibilities of being easily integrated with traditional microfluidic systems for analytical and biotechnological applications.
我们描述了一种新颖而简单的机制，即在单个开放微通道中使用类似于 Nafion 的具有图案化表面的选择性纳米多孔膜来诱导离子浓差极化 (ICP)。这种具有图案化表面的 Nafion 膜可以通过纳米孔簇从阳极快速仅将阳离子传输到阴极，从而可以在 Nafion 膜附近产生 ICP 现象。在这项工作中，我们在各种电场下对靠近 Nafion 膜的传输现象和离子浓度分布进行了表征，并表明基于单通道的 ICP (SC-ICP) 受 Nafion 膜厚度、施加电场强度和缓冲溶液离子强度的影响。我们还强调，SC-ICP 器件相对于以前的双通道 ICP (DC-ICP) 器件具有几个优势：易于制造的工艺、本质上无泄漏、仅需要一对电极的简单实验设置、稳定且坚固的 ICP 快速诱导、低电阻有助于避免焦耳加热和膜的选择性击穿，但允许像开放的普通微通道一样高的体积流量。作为应用的一个例子，我们证明了 SC-ICP 器件不仅在大规模并行微通道中浓缩蛋白质方面具有很大的潜力，而且还能够在芯片上同时连续浓缩和裂解细菌细胞；因此，细胞内的蛋白质被提取出来，与浓缩的细胞分离，然后在靠近 Nafion 膜的不同位置进行预浓缩。因此，我们相信 SC-ICP 器件更容易与传统微流控系统集成，用于分析和生物技术应用。
