Hydration and Nanoconfined Water: Insights from Computer Simulations.

Area of Science:

• Physical Chemistry
• Biophysics
• Materials Science

Background:

• Water's structure and dynamics at interfaces and under nanoconfinement are critical for hydration, reaction dynamics, and biological processes.
• Understanding nanoscale hydrophobicity is vital for both fundamental science and applied fields like biomolecular interactions and synthetic materials design.

Purpose of the Study:

• To investigate the structure and dynamics of water at various interfaces and confinement conditions using molecular dynamics simulations.
• To explore the impact of interface geometry, chemical nature, and confinement on water's hydrogen bonding and local hydration properties.

Main Methods:

• Molecular dynamics simulations were employed to study water behavior.
• Simulations covered model hydrophobic interfaces, self-assembled monolayers, proteins, and phospholipid membranes.
• Analysis included water molecule orientation, hydrogen bond coordination, and local hydrophobicity measures.

Main Results:

• Water molecules at extended interfaces tend to minimize hydrogen bond (HB) coordination, leading to oriented hydration layers, sometimes ice-like.
• Hydrophobic cavities show size-dependent filling: subnanometric cavities remain empty, while larger ones exhibit alternating filled/dry states with internal HB networks.
• Complex interfaces (proteins, membranes) demonstrate how chemical and geometrical factors influence local hydration.

Conclusions:

• Water's hydration properties are highly context-dependent and non-additive in nanoenvironments, influencing biological and materials science applications.
• Insights into water-protein and water-membrane interactions are crucial for understanding biological function and designing novel nanomaterials.
• A local hydrophobicity measure is presented, relevant for predicting binding and self-assembly phenomena in aqueous systems.