Dynamic heterogeneity controls diffusion and viscosity near biological interfaces

At a nanometre scale, the behaviour of biological fluids is largely governed by interfacial physical chemistry. This may manifest as slowed or anomalous diffusion. Here we describe how measures developed for studying glassy systems allow quantitative measurement of interfacial effects on water dynam...

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Bibliographic Details
Published in:Nature communications 2014-01, Vol.5 (1), p.3034-3034, Article 3034
Main Authors: Pronk, Sander, Lindahl, Erik, Kasson, Peter M.
Format: Article
Language:English
Subjects:
119/118
639/301/119/544
639/766/189
Anomalous Diffusion
Confinement
Diffusion
Glass
Humanities and Social Sciences
Hydration Dynamics
Hydrodynamics
Liquid Water
Models, Biological
Molecular Simulation
multidisciplinary
Nanostructures
NMR
Nuclear magnetic resonance
Protein
Random-Walks
Science
Silicon Dioxide
Solvents
Surface Tension
Surfaces
Time
Viscosity
Water
Water Dynamics
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Summary:At a nanometre scale, the behaviour of biological fluids is largely governed by interfacial physical chemistry. This may manifest as slowed or anomalous diffusion. Here we describe how measures developed for studying glassy systems allow quantitative measurement of interfacial effects on water dynamics, showing that correlated motions of particles near a surface result in a viscosity greater than anticipated from individual particle motions. This effect arises as a fundamental consequence of spatial heterogeneity on nanometre length scales and applies to any fluid near any surface. Increased interfacial viscosity also causes the classic finding that large solutes such as proteins diffuse much more slowly than predicted in bulk water. This has previously been treated via an empirical correction to the solute size: the hydrodynamic radius. Using measurements of quantities from theories of glass dynamics, we can now calculate diffusion constants from molecular details alone, eliminating the empirical correction factor. Many biological reactions typically occur in a fluid that is near to a surface. Here, the authors apply theory used to describe glassy systems to quantitatively understand these effects, finding that correlated particle motion near the interface leads to an increase in fluid viscosity.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms4034