Anomalous anisotropic diffusion dynamics of hydration water at lipid membranes.
The diffusional water dynamics in the hydration layer of a dipalmitoylphosphatidylcholine bilayer is studied using molecular dynamics simulations. By mapping the perpendicular water motion on the ordinary diffusion equation, we disentangle free energetic and friction effects and show that perpendicular diffusion is strongly reduced. The lateral water motion exhibits anomalous diffusion up to several nanoseconds and is characterized by even further decreased diffusion coefficients, which by comparison with coarse-grained simulations are explained by the transient corrugated effective free energy landscape imposed by the lipids. This is in contrast to homogenous surfaces, where boundary hydrodynamic theory quantitatively predicts the anisotropy of water diffusion.
Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany and Physics Department, Technische Universität München, 85748 Garching, Germany.
Yann
Y
von Hansen
Stephan
S
Gekle
Roland R
RR
Netz
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D016880:Anisotropy; D004058:Diffusion; D057446:Hydrodynamics; D008051:Lipid Bilayers / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D014867:Water / Q000737:chemistry*
D008051:Lipid Bilayers; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine