Effect of channel wettability on the single-file water transport in sub-nanometer channel

The transport of liquid in nanochannels is of great importance in theoretical studies and industrial applications. Recently, the single-file transport of water molecules observed in biological channels, such as in aquaporin-1 (AQP1), has been considered a potential way to achieve rapid water transport. Herein, we established ten biomimetic water channel models by changing the wettability and wettability distribution of sub-nanometer channels, and studied water transport process from a full reservoir through each biomimetic water channel into an empty reservoir under different external pressures using molecular dynamics simulation. The results show that channel wettability and external pressure affect the filling form of water molecules in the channel, and the water molecules can only be successfully transported when the water molecules can fill the channel for a long time or fill the channel all the time. Specifically, the hydrophilic channel is more conducive to the single-file transport of water molecules. Furthermore, when the channel is hydrophobic, increasing the local hydrophilicity of the channel will significantly reduce the energy barrier for water molecules to pass through the channel, which facilitates the water transport in hydrophobic channel. Based on this, although the selective filter channel in AQP1 as a whole does not have good hydrophilicity, we speculate that one of the reasons for the high water permeability of AQP1 may be the special wettability distribution of the filter, which is the staggered arrangement of hydrophobic and hydrophilic regions.