A Step-by-Step Process-Induced Unidirectional Oriented Water Wire in the Nanotube.

Area of Science:

• Physical Chemistry
• Biophysics
• Materials Science

Background:

• Water molecule orientation is critical for efficient transport in nanotubes.
• Existing models propose concerted mechanisms for water chain flips, enabling unidirectional flow under external fields.

Purpose of the Study:

• To investigate the mechanism of water chain flips in nanotubes.
• To determine the conditions necessary for unidirectional water flow in carbon nanotubes without external fields.

Main Methods:

• Molecular dynamics simulations
• First-principles calculations

Main Results:

• The water chain flip mechanism in nanotubes is step-by-step, contradicting the concerted mechanism theory.
• Over 20 water molecules are required to sustain unidirectional single-file flow in carbon nanotubes for seconds without an external field.

Conclusions:

• The step-by-step water chain flip mechanism challenges previous understandings of water transport in nanotubes.
• The findings suggest that external fields may not be necessary for maintaining unidirectional water flow in biological channels like cell membranes due to their size exceeding the required length threshold.