Pore structure and function of synthetic nanopores with fixed charges:: tip shape and rectification properties
Pore structure and function of synthetic nanopores with fixed charges:: tip shape and rectification properties
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DOI：
10.1088/0957-4484/19/31/315707
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发表时间：
2008-08-06
期刊：
影响因子：
3.5
通讯作者：
Mafe, Salvador
中科院分区：
文献类型：
--
作者：
Ramirez, Patricio;Apel, Pavel Yu;Mafe, Salvador
我们在前期实验研究的基础上，对不对称纳米孔的结构（尖端形状和尺寸）与功能（选择性和整流）之间的关系进行了完整的理论研究。理论模型使用基于 Nernst-Planck 方程的连续介质方法。根据我们的结果，纳米孔传输特性，如电流-电压（I-V）特性、电导、整流比和选择性，主要由孔尖端的形状（我们区分了子弹状、圆锥形、喇叭状和混合形状）和孔表面电荷的浓度决定。因此，实际应用中的纳米孔性能不仅取决于底部和尖端开口，还取决于孔形状。特别是，我们表明，根据假设的孔隙形状，根据孔隙电导估计的孔隙开口尺寸可能有很大不同。获得的结果对于纳米孔、纳米移液管和纳米电极的设计也具有实际意义，其中附着在纳米结构上的电荷与限制在内部溶液体积减小的移动电荷之间的电相互作用决定了实际应用中的器件性能。由于单轨道是纳米多孔膜的基本构建块，因此理解和控制其各自特性对于使用相同纳米孔阵列的蛋白质分离、水淡化和生物分子检测也至关重要。
We present a complete theoretical study of the relationship between the structure (tip shape and dimensions) and function (selectivity and rectification) of asymmetric nanopores on the basis of previous experimental studies. The theoretical model uses a continuum approach based on the Nernst-Planck equations. According to our results, the nanopore transport properties, such as current-voltage (I-V) characteristics, conductance, rectification ratio, and selectivity, are dictated mainly by the shape of the pore tip (we have distinguished bullet-like, conical, trumpet-like, and hybrid shapes) and the concentration of pore surface charges. As a consequence, the nanopore performance in practical applications will depend not only on the base and tip openings but also on the pore shape. In particular, we show that the pore opening dimensions estimated from the pore conductance can be very different, depending on the pore shape assumed. The results obtained can also be of practical relevance for the design of nanopores, nanopipettes, and nanoelectrodes, where the electrical interactions between the charges attached to the nanostructure and the mobile charges confined in the reduced volume of the inside solution dictate the device performance in practical applications. Because single tracks are the elementary building blocks for nanoporous membranes, the understanding and control of their individual properties should also be crucial in protein separation, water desalination, and bio-molecule detection using arrays of identical nanopores.