Ion Transport in Electrically Imperfect Nanopores
Ion Transport in Electrically Imperfect Nanopores
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DOI：
10.1021/acsnano.0c04453
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发表时间：
2020-08-25
期刊：
影响因子：
17.1
通讯作者：
Aluru, Narayana R.
中科院分区：
文献类型：
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作者：
Noh, Yechan;Aluru, Narayana R.
离子在低离子浓度下通过带电纳米孔的传输受表面电导控制。几个实验已经报道了表面电导率和离子浓度之间的各种幂律关系，即G（surf）与c(0)（alpha）成正比。然而，变化指数alpha的物理起源尚不清楚。通过对不同孔径、长度和表面电荷密度进行广泛的粗粒度分子动力学模拟，我们观察到即使表面电荷恒定，幂律指数也会发生变化，并表明α取决于纳米孔的电“完美”程度。具体来说，当孔中溶液的净电荷不足以保证电中性时，孔在电上是“不完美的”，这种纳米孔会根据“不完美”的程度表现出不同的α。我们提出了电“不完美”纳米孔的离子电导理论，不仅解释了各种幂律关系，而且描述了文献中大多数可用的实验数据。
Ionic transport through a charged nanopore at low ion concentration is governed by the surface conductance. Several experiments have reported various power-law relations between the surface conductance and ion concentration, i.e., G(surf) proportional to c(0)(alpha). However, the physical origin of the varying exponent, alpha, is not yet clearly understood. By performing extensive coarse-grained Molecular Dynamics simulations for various pore diameters, lengths, and surface charge densities, we observe varying power-law exponents even with a constant surface charge and show that alpha depends on how electrically "perfect" the nanopore is. Specifically, when the net charge of the solution in the pore is insufficient to ensure electro-neutrality, the pore is electrically "imperfect" and such nanopores can exhibit varying alpha depending on the degree of "imperfectness". We present an ionic conductance theory for electrically "imperfect" nanopores that not only explains the various power-law relationships but also describes most of the experimental data available in the literature.