School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.
Beijing National Laboratory for Molecular Science, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China.
Anal Chem. 2022 Mar 15;94(10):4328-4334. doi: 10.1021/acs.analchem.1c05025. Epub 2022 Mar 4.
Nanofluidic ionic diodes have attracted much attention, because of the unique property of asymmetric ion transport and promising applications in molecular sensing and biosensing. However, it remains a challenge to fabricate diode-like nanofluidic system with molecular-size pores. Herein, we report a new and facile approach to construct nanofluidic ionic diode by in situ asymmetric growth of metal-organic frameworks (MOFs) in nanochannels. We implement microwave-assisted strategy to obtain asymmetric distribution of MOFs in porous anodic aluminum oxide with barrier layer on one side. After etching the barrier layer and modifying with positively charged molecules, the nanofluidic device possesses asymmetric geometry and surface charge, performing the ionic current rectification (ICR) behavior in different electrolyte concentrations. Moreover, the ICR ratio is readily regulated with visible light illumination mainly due to the enhancement of surface charge of MOFs, which is further confirmed by finite element simulation. This study provides a reliable way to build the nanofluidic platform for investigating the asymmetric ion transport through the molecular-size pores, which is envisaged to be important for molecular sensing based on ICR with molecular-size pores.
纳米流体离子二极管因其独特的不对称离子输运特性和在分子传感和生物传感方面的应用前景而备受关注。然而，用具有分子尺寸孔的纳米流体制备类似二极管的系统仍然是一个挑战。在此，我们报告了一种新的、简便的方法，通过在纳米通道中进行金属有机框架（MOFs）的原位不对称生长来构建纳米流体离子二极管。我们采用微波辅助策略，在一侧具有阻挡层的多孔阳极氧化铝中获得 MOFs 的不对称分布。在蚀刻阻挡层并修饰带正电荷的分子后，纳米流器件具有不对称的几何形状和表面电荷，在不同的电解质浓度下表现出离子电流整流（ICR）行为。此外，ICR 比可以通过可见光照射轻松调节，主要是由于 MOFs 的表面电荷增强，这进一步通过有限元模拟得到证实。本研究为通过分子尺寸孔研究不对称离子输运提供了一种可靠的方法，这对于基于分子尺寸孔的 ICR 的分子传感具有重要意义。
