Layer-by-Layer Assembly of Polyelectrolytes into Ionic Current Rectifying Solid-State Nanopores: Insights from Theory and Experiment
Layer-by-Layer Assembly of Polyelectrolytes into Ionic Current Rectifying Solid-State Nanopores: Insights from Theory and Experiment
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DOI：
10.1021/ja101014y
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发表时间：
2010-06-23
影响因子：
15
通讯作者：
Azzaroni, Omar
中科院分区：
文献类型：
--
作者：
Ali, Mubarak;Yameen, Basit;Azzaroni, Omar
基于单锥形纳米孔的离子整流器的分子设计正受到科学界越来越多的关注。该主题的部分吸引力依赖于对传感器和流体纳米致动器的兴趣，这些传感器和流体纳米致动器基于离子和分子通过纳米孔架构的传输，这些纳米孔架构可以容易地集成到功能系统中。孔壁的化学修饰不仅控制这些纳米结构的直径，而且控制它们的选择性和传输特性。为了赋予固态纳米孔的选择性，有必要开发和探索用于使孔壁功能化的新方法。因此，能够作为选择性离子通道或智能纳米流体传感器的功能性纳米孔的产生关键取决于我们在具有与构建块本身的大小相当的尺寸的受限几何形状内以可预测的方式组装和构建分子架构的能力。在这种情况下，逐层沉积的聚电解质提供了一个简单的过程，用于创建纳米级的超分子组件显示各种各样的功能特性。在这项工作中，我们描述了第一次的集成层的逐层的超分子组装成单一的锥形纳米孔，以研究和探索所产生的功能特性，从创建带电的超分子组装内的约束几何形状的纳米流体设备。为了解决这个具有挑战性的话题，我们使用了一种结合实验和理论的方法来阐明和量化超分子组装过程中纳米孔内部发生的静电变化。通过聚烯丙胺盐酸盐（PAH）和聚苯乙烯磺酸盐（PSS）在孔表面的连续逐层吸附，形成多层膜。我们的研究结果表明，与PAH/PSS组件功能化的单锥形纳米孔的电荷传输性能是高度依赖于组装在孔壁上的层数。与沉积在平面表面上的PAH/PSS膜（定量电荷反转）相比，孔壁的表面电荷随着组装到纳米孔中的PAH/PSS层的数量而显著降低。这种行为归因于纳米约束诱导的结构重组的纳米孔层，导致有效形成离子对，并促进在纳米孔壁上的净固定电荷显着减少。我们认为，这些结果是最重要的相关性的纳米孔，纳米移液管，和纳米电极使用带电超分子组件的修改，以及在“软纳米技术”的重要性，提供的结构复杂性，诱导纳米限制，可以定义自组装聚合物纳米结构的功能特性。
Molecular design of ionic current rectifiers created on the basis of single conical nanopores is receiving increasing attention by the scientific community. Part of the appeal of this topic relies on the interest in sensors and fluidic nanoactuators based on the transport of ions and molecules through nanopore architectures that can readily be integrated into functional systems. The chemical modification of the pore walls controls not only the diameter of these nanoarchitectures but also their selectivity and transport properties. In order to confer selectivity to solid-state nanopores, it is necessary to develop and explore new methods for functionalizing the pore walls. Hence, the creation of functional nanopores capable of acting as selective ion channels or smart nanofluidic sensors depends critically on our ability to assemble and build up molecular architectures in a predictable manner within confined geometries with dimensions comparable to the size of the building blocks themselves. In this context, layer-by-layer deposition of polyelectrolytes offers a straightforward process for creating nanoscopic supramolecular assemblies displaying a wide variety of functional features. In this work, we describe for the first time the integration of layer-by-layer polyelectrolyte assemblies into single conical nanopores in order to study and explore the functional features arising from the creation of charged supramolecular assemblies within the constrained geometry of the nanofluidic device. To address this challenging topic, we used a combined experimental and theoretical approach to elucidate and quantify the electrostatic changes taking place inside the nanopore during the supramolecular assembly process. The multilayered films were built up through consecutive layer-by-layer adsorption of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) on the pore surface. Our results show that the charge transport properties of single conical nanopores functionalized with PAH/PSS assemblies are highly dependent on the number of layers assembled on the pore wall. In contrast to what happens with PAH/PSS films deposited on planar surfaces (quantitative charge reversal), the surface charge of the pore walls decreases dramatically with the number of PAH/PSS layers assembled into the nanopore. This behavior was attributed to the nanoconfinement-induced structural reorganization of the polyelectrolyte layers, leading to the efficient formation of ion pairs and promoting a marked decrease in the net fixed charges on the nanopore walls. We consider that these results are of paramount relevance for the modification of nanopores, nanopipets, and nanoelectrodes using charged supramolecular assemblies, as well as of importance in "soft nanotechnology" provided that structural complexity, induced by nanoconfinement, can define the functional properties of self-assembled polymeric nanostructures.