A mechanical nanogate based on a carbon nanotube for reversible control of ion conduction
A mechanical nanogate based on a carbon nanotube for reversible control of ion conduction
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基于碳纳米管的机械纳米门，用于可逆控制离子传导
DOI：
10.1039/c3nr06238d
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发表时间：
2014
期刊：
影响因子：
6.7
通讯作者：
Zhou Jian
中科院分区：
文献类型：
--
作者：
He Zhongjin;Corry Ben;Lu Xiaohua;Zhou Jian
在许多纳米级器件和纳滤膜中，控制质量通过纳米通道是至关重要的。控制物质跨细胞膜运输的生物通道中的门可以为这一目的提供灵感。许多生物通道中的门是由由疏水残基组成的缩窄环形成的，即使它们没有完全被物理阻塞，也可以阻止离子传导。在这项工作中，我们使用分子动力学模拟来设计受这种疏水门机制启发的纳米门。用外力使碳纳米管（12,12）变形，可以在管的中心形成控制离子传导的疏水收缩。模拟结果表明，施加的力的大小越大，收缩越窄，电场作用下K+和Cl−的通量越低。当施加的力大于5nn时，由于部分脱水，收缩阻止了K+和Cl−的传导，同时允许明显的水通量。离子传导可以在力收回时恢复到未受干扰的水平，表明纳米门的可逆性。这种力可以通过可用的实验设备施加，例如原子力显微镜（AFM）的尖端。研究发现，在连续充满水的疏水收缩中，部分脱水足以关闭通道，而完全脱水则不一定需要。这种机械变形的纳米门有许多潜在的应用，比如在纳米流体系统中用作可逆控制离子传导的阀门，以及用于海水淡化和水处理的高性能纳米机器。
Control of mass transport through nanochannels is of critical importance in many nanoscale devices and nanofiltration membranes. The gates in biological channels, which control the transport of substances across cell membranes, can provide inspiration for this purpose. Gates in many biological channels are formed by a constriction ringed with hydrophobic residues which can prevent ion conduction even when they are not completely physically occluded. In this work, we use molecular dynamics simulations to design a nanogate inspired by this hydrophobic gating mechanism. Deforming a carbon nanotube (12,12) with an external force can form a hydrophobic constriction in the centre of the tube that controls ion conduction. The simulation results show that increasing the magnitude of the applied force narrows the constriction and lowers the fluxes of K+ and Cl− found under an electric field. With the exerted force larger than 5 nN, the constriction blocks the conduction of K+ and Cl− due to partial dehydration while allowing for a noticeable water flux. Ion conduction can revert back to the unperturbed level upon force retraction, suggesting the reversibility of the nanogate. The force can be exerted by available experimental facilities, such as atomic force microscope (AFM) tips. It is found that partial dehydration in a continuous water-filled hydrophobic constriction is enough to close the channel, while full dewetting is not necessarily required. This mechanically deformed nanogate has many potential applications, such as a valve in nanofluidic systems to reversibly control ion conduction and a high-performance nanomachine for desalination and water treatment.