摘要/Abstract
生命体内的离子通道在各种生物功能调节过程及生命活动中具有重要的意义.模仿生物孔道的离子输运性质，构筑人工纳米通道，并研究人工纳米通道的离子输运性质是一项具有重大意义的研究课题.本文通过双面阳极氧化和原位扩孔结合的方法制备了对称结构的沙漏形氧化铝纳米通道.通过在对称结构的沙漏形氧化铝（AAO）纳米通道一侧粘贴一层透明胶带，经过热处理后，获得了一种具有高整流比的有机-无机异质纳米通道.基于非对称的结构和电荷分布，氧化铝纳米通道与有机纳米通道在复合区域形成异质结构.由于多孔AAO纳米通道和有机纳米通道的协同效应，异质纳米通道表现出独特的纳米流体二极管特性，即在比较宽的pH范围内具有单一的整流方向.在该体系中，氧化铝纳米通道内壁的羟基和有机纳米通道内壁的羧基在不同pH值下所带电荷性质不同，使异质结构纳米通道内壁表面电荷的性质和电荷密度发生改变，可以通过调节体系的pH来调控通道内的离子传输.
关键词: 纳米通道, 异质结构, pH调控, 纳米流体二极管, 离子整流
Ion channels in cell membranes play crucial roles in many biological activities. Many artificial nanochannels have been constructed to mimic the organism functions and sensitive to external stimuli. The artificial nanochannels have drawn enormous research attention due to their potential applications and simplicity. In this work, the hourglass shaped alumina nanochannels were fabricated using a double-sided anodization method with an in situ pore opening process. We constructed organic-inorganic heterogeneous nanochannels based on anodic alumina oxide (AAO) and transparent tape by the method of heat treatment. The surface morphology and component of nanoporous heterogeneous membrane were characterized by scanning electron microscope (SEM) and ATR-FTIR spectrum. These two kinds of nanochannels have differential diameters and amphoteric characteristics. Heterogeneous nanochannels are composed of organic nanochannels and AAO pores containing carboxyl and hydroxyl groups, respectively. Ion transport through the heterogeneous nanochannels can be modulated, because of the protonation state of the nanochannels under different pH conditions. Because of the heterogeneity of structure and charge, heterojunction is formed in the junction of anodic alumina oxide nanochannels and organic nanochannels. Such an abrupt junction yields a more efficient control of ion accumulation and depletion in the heterogeneous nanochannel. The ionic transport properties of heterogeneous nanochannels can be studied by measuring the current-voltage (I-V) curves. The heterogeneous nanochannels exhibit pH sensitivity. Changing the pH value from acidic to alkaline values, a significant decrease in positive charges and the deprotonated carboxyl group with negative charges can be observed. Due to the synergistic effect of the nanoporous AAO and organic nanochannels, heterogeneous nanochannels exhibit high and controllable rectification with single rectification direction over a wide pH range. The diode-like behavior is quantified by measuring the current rectification ratios. The novel strategy introduced here is a low-cost, scalable, and robust alternative for the fabrication of heterogeneous nanochannels system for nanofluidic applications. This porous heterogeneous membrane have potential applications in the fields of ion transport, separation of biomolecules and energy conversion system.
Key words: ion channels, heterogeneous nanochannels, pH sensitivity, nanofluidic diode, rectification
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