Ion fluxes through nanopores and transmembrane channels

Abstract

We introduce an implicit solvent Molecular Dynamics approach for calculating ionic fluxes through narrow nanopores and transmembrane channels. The method relies on a dual-control-volume grand-canonical molecular dynamics (DCV-GCMD) simulation and the analytical solution for the electrostatic potential inside a cylindrical nanopore recently obtained by Levin [Europhys. Lett. 76, 163 (2006)]. The theory is used to calculate the ionic fluxes through an artificial transmembrane channel which mimics the antibacterial gramicidin A channel. Both current-voltage and current-concentration relations are calculated under various experimental conditions. We show that our results are comparable to the characteristics associated to the gramicidin A pore, especially the existence of two binding sites inside the pore and the observed saturation in the current-concentration profiles.

2D nanoporous membrane for cation removal from water: Effects of ionic valence, membrane hydrophobicity, and pore size

“…Therefore, it is more energetically favorable for the cation to remain in the bulk solution instead of stripping off the water and entering the pore. 50 As the pore diameter increases, this energetic penalty becomes smaller. In addition, the valence plays a crucial role here, with the monovalent ions having a smaller penalty than divalent and trivalent cations.…”

Influence of disordered porous media on the anomalous properties of a simple water model

“…In order to answer these questions water-like atomistic or continuous effective potential models were explored. The confining geometries could be plates [27][28][29][30][31][32][33][34][35][36][37], one pore [38][39][40][41][42][43][44][45][46], and a disordered matrix [43,52,53,[55][56][57]. The results for the melting temperature obtained within these approaches are controversial, while results for SPC/E water show that the melting temperature for hydrophobic plates is lower than the melting for the unconfined system and higher than for the system confined by hydrophilic walls, for the mW model no difference between the melting temperatures due to the hydrophobicity [47] is found.…”

Enhanced permeation of single-file water molecules across a noncylindrical nanochannel

“…It is widely accepted that the external conditions of the nanochannel system greatly affect the permeation of water molecules. So, many external conditions (say, adding external mechanical forces, pressure gradient, or electric fields or charges) have received much attention in the field for studying the transportation of water molecules through nanochannels, while taking the nanochannel shape to be cylindrical [29][30][31][32][33][34][35][36][37][38][39][40]. Recently, a new particle separation mechanism has been reported according to the combined * jphuang@fudan.edu.cn action of a driving force and an entropic rectification of the Brownian fluctuations caused by the asymmetric shape of the channel [41].…”