Osmotic Water Permeation through a Carbon Nanotube

Abstract

Osmosis are essential for not only the application of nanofluidic devices but also the understanding of working principles of biological transmembrane proteins. Despite considerable experimental interests, comprehensive simulation work is still lacking, possibly because of the periodic boundary condition that inevitably leads to the spontaneous exchange of two side reservoirs. To eliminate this disadvantage, herein we design a simple model system by introducing a dipalmitoylphosphatidylcholine bilayer into a common carbon-nanotube (CNT)-based setup, which allows long-time osmotic simulations. Interestingly, the osmotic water flux exhibits an excellent linear relation with the concentration gradient and an Arrhenius relation with the temperature, which highly coincides with recent experimental observations. Furthermore, the osmotic flux can be quantitatively comparable to not only the experimental CNTs and protein channels but also the theoretical estimation from the Hagen-Poiseuille equation. The designed simulation model could open a new window for future studies on osmosis.