서강대학교

초록/요약

Aquaporins enable fast water transport and water selectivity. This special function of aquaporins gains attentions for the development of efficient water transporters. In this study, we mimicked aquaporins with hourglass-shaped nanopores with a positive charge. We investigated water transport phenomena with varying hydrophobicity of the pore and pool regions of hourglass-shaped nanopore model. We observed that similar phenomena occurred with varying pool contact angles. We found that there was a certain degree of hydrophobicity resulting in the highest water flux. The entrance region, the center region, and the exit region of the pore exhibited different water transport phenomena. In the center region, the average distance between water molecules decreased constantly as pore hydrophobicity increased. There were opposite results in the entrance region and the exit region. We investigated detailed structure of water molecules and found that single-file water structure formed in the center region. On the contrary, water molecules became bulk-state-like in the entrance and exit regions. We calculated density profile of water molecules and found that the lowest energy barrier occurred on the hydrophobic state of θpore = 101°. We also made cylindrical nanopore model to compare with results of hourglass-shaped nanopore model. We found that there were different water transport phenomena. The average number of water molecules and water flux was much lower than those of hourglass-shaped nanopore model. The average distance between water molecules didn’t change so much in the entrance and exit regions. On the contrary, it increased constantly in the center region. For the average number of hydrogen bonds, it slightly decreased in center region as hydrophobicity increases. We assumed that water transport phenomena in the center region had a little relationship with the water flux and water transport was much harder in cylindrical nanopore than hourglass-shaped nanopore. We expect that our research would provide a reference for designing aquaporin-mimic nanopores.