Transport properties of single-file water molecules inside a carbon nanotube biomimicking water channel.

The single-file water transport through a biomimic water channel consisting of a (6,6) carbon nanotube (CNT) with different types of external point charges is studied using molecular dynamics simulations. It is demonstrated that, as in the aquaporins, asymmetrically positioned charges cannot generate robust unidirectional water flow in the CNT. Thermal fluctuation in bulk water competes with charge affinity to steer the water transport, resulting in nonmonotonic flow with intermittent reversal of transport direction. The energetic analysis suggests that the water-water interaction, determined by dipole orientation configuration, influences the transport rate significantly. These findings can provide correct biomimic understanding of water transport properties and will benefit the design of efficient functional nanofluidic devices.