Analysis of the dynamics of supercooled water in carbon materials using reactive molecular dynamics simulations

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K05209
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 28030:Nanomaterials-related
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: Mizuguchi Tomoko 京都工芸繊維大学, 材料化学系, 准教授 (90758963)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: カーボンナノチューブ / 反応力場 / 分子動力学シミュレーション / OHラジカル / 脂質膜 / 水の透過

Outline of Final Research Achievements

To investigate the behavior of water within a carbon nanotube (CNT), molecular dynamics simulations using the reactive force field, ReaxFF, were carried out. First, four different parameter sets of ReaxFF were evaluated, revealing significant variations in the rate of water penetration into the CNT depending on the chosen parameter set. One particular parameter set precluded any water penetration into the CNT. Subsequently, simulations were conducted to examine the permeation of water and OH radicals through the CNT vertically penetrating a lipid membrane. The findings indicated that the CNT, featuring hydrogen terminations at its ends, allow water to pass through, but not OH radicals. For comparison, additional permeation simulations were performed with aquaporin incorporated into the lipid membrane. Intriguingly, it was observed that a small amount of OH radicals managed to traverse the aquaporin channel by forming hydrogen bonds with water.

Free Research Field

ソフトマター物理

Academic Significance and Societal Importance of the Research Achievements

CNTを用いた膜透過の研究は、CNTの末端修飾により選択的な分子透過システムを実現する可能性を秘めている。OHラジカルをガン細胞に選択的に透過させることができれば、ガン細胞を狙い撃ちした治療システムの構築に繋がる。アクアポリンを透過させるシミュレーションでは、入り口付近にエネルギー障壁があることが分かったので、CNTの末端修飾により入り口の障壁を下げてやれば、水との複合体として透過が可能かもしれない。ラジカルのような反応性が高い種を扱うときには、反応力場を用いたシミュレーションが力を発揮するので、そのパラメータ調整を含めて計算を進めていくことが重要である。