Extended surfaces modulate and can catalyze hydrophobic effects

TL;DR

This study investigates how interfaces influence hydrophobic effects using simulations and theory, revealing that hydrophobic surfaces weaken assembly forces and may catalyze protein unfolding and aggregation.

Contribution

It demonstrates how interfaces modulate hydrophobic phenomena and introduces a theoretical framework to explain these effects across different chemistries and temperatures.

Findings

Hydrophobic surfaces weaken assembly forces compared to bulk water.

The weakening of forces increases with temperature.

Interfaces may catalyze protein unfolding and aggregation.

Abstract

Interfaces are a most common motif in complex systems. To understand how the presence of interfaces affect hydrophobic phenomena, we use molecular simulations and theory to study hydration of solutes at interfaces. The solutes range in size from sub-nanometer to a few nanometers. The interfaces are self-assembled monolayers with a range of chemistries, from hydrophilic to hydrophobic. We show that the driving force for assembly in the vicinity of a hydrophobic surface is weaker than that in bulk water, and decreases with increasing temperature, in contrast to that in the bulk. We explain these distinct features in terms of an interplay between interfacial fluctuations and excluded volume effects---the physics encoded in Lum-Chandler-Weeks theory [J. Phys. Chem. B 103, 4570--4577 (1999)]. Our results suggest a catalytic role for hydrophobic interfaces in the unfolding of proteins, for example, in the interior of chaperonins and in amyloid formation.