Network Topology in Water Nanoconfined between Phospholipid Membranes

Abstract

Water provides the driving force for the assembly and stability of many cellular components. Despite its impact on biological functions, a nanoscale understanding of the relationship between its structure and dynamics under soft confinement has remained elusive. As expected, water in contact with biological membranes recovers its bulk density and dynamics at $\sim 1$ nm from phospholipid headgroups but surprisingly enhances its intermediate-range order (IRO) over a distance, at least, twice as large. Here, we explore how the IRO is related to the water's hydrogen bond network (HBN) and its coordination defects. We characterize the increased IRO by an alteration of the HBN up to more than eight coordination shells of hydration water. The HBN analysis emphasizes the existence of a bound-unbound water interface at $\sim 0.8$ nm from the membrane. The unbound water has a distribution of defects intermediate between bound and bulk water, but with density and dynamics similar to bulk, while bound water has reduced thermal energy and much more HBN defects than low-temperature water. This observation could be fundamental for developing nanoscale models of biological interactions and for understanding how alteration of the water structure and topology, for example, due to changes in extracellular ions concentration, could affect diseases and signaling. More generally, it gives us a different perspective to study nanoconfined water.

References in corpus (13)

• Understanding water's anomalies with locally favored structures
• The Individual and Collective Effects of Exact Exchange and Dispersion Interactions on the Ab Initio Structure of Liquid Water
• Local Structure Analysis in $Ab$ $Initio$ Liquid Water
• Polyamorphism of ice at low temperatures from constant-pressure simulations
• Evolution of the structure of amorphous ice - from low-density amorphous (LDA) through high-density amorphous (HDA) to very high-density amorphous (VHDA) ice
• The quest for self-consistency in hydrogen-bond definitions
• Unravelling the contribution of local structures to the anomalies of water: the synergistic action of several factors
• Large-scale structure and hyperuniformity of amorphous ices
• A local order metric for condensed phase environments
• Searching for crystal-ice domains in amorphous ices
• Relations between the diffusion anomaly and cooperative rearranging regions in a hydrophobically nanoconfined water monolayer
• Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for Increasing Hydration Level: All-Atoms Molecular Dynamics
• Root-Growth of Boron Nitride Nanotubes: Experiments and \textit{Ab Initio} Simulations

Cited by in corpus (5)

• Nanoconfined fluids: Uniqueness of water compared to other liquids
• Using Car-Parrinello simulations and microscopic order descriptors to reveal two locally favored structures with distinct molecular dipole moments and dynamics in ambient liquid water
• Hydrophobic homopolymer's coil-globule transition and adsorption onto a hydrophobic surface under different conditions
• Transport Dynamics of Water Molecules Confined between Lipid Membranes
• Devitrification and Melting Dynamics in Vapor Deposited Water Ice