Curvature Dependence of Hydrophobic Hydration Dynamics

TL;DR

This study explores how the curvature of hydrophobic surfaces influences water dynamics and hydrogen bonding, revealing non-monotonic size dependence and topology effects through molecular simulations.

Contribution

It provides new insights into the curvature-dependent hydration dynamics and explains anomalous diffusion phenomena near small hydrophobic solutes.

Findings

Water diffusivity shows non-monotonic dependence on solute size.

Hydrogen bond kinetics exhibit extrema near the structural crossover length.

Anomalous diffusion near small solutes explained by topology effects.

Abstract

We investigate the curvature-dependence of water dynamics in the vicinity of hydrophobic spherical solutes using molecular dynamics simulations. For both, the lateral and perpendicular diffusivity as well as for H-bond kinetics of water in the first hydration shell, we find a non-monotonic solute-size dependence, exhibiting extrema close to the well-known structural crossover length scale for hydrophobic hydration. Additionally, we find an apparently anomalous diffusion for water moving parallel to the surface of small solutes, which, however, can be explained by topology effects. The intimate connection between solute curvature, water structure and dynamics has implications for our understanding of hydration dynamics at heterogeneous biomolecular surfaces.