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Local water diffusivity as a molecular probe of surface hydrophilicity
Published online by Cambridge University Press: 12 December 2014
Abstract
The study of water’s functional role on hydrophilic surfaces of biological and soft materials benefits from experimental measurements that operate at finer length and time scales than contact-angle-measurement-derived surface wettability. We show that local translational diffusivity permits the empirical determination of local hydrophilicity by means of Overhauser dynamic nuclear polarization (ODNP) amplified 1H NMR relaxometry. Large unilamellar vesicles (LUVs) in dilute bulk water solution serve as good model hydrophilic surfaces, and their surface water diffusion was shown to be partially or entirely decoupled from the bulk water viscosity, with the extent of decoupling dependent on the surface activity of the particular viscogen chosen. The effective hydrophilicity of a hydrated LUV surface in solution was further shown to be tunable by specific ions or osmolytes dissolved in solution, and the chemical makeup of a surface can give rise to a heterogeneous hydration dynamics landscape, as demonstrated on protein surfaces. ODNP-derived surface water diffusivity is suggested to be a unique tool for the site-specific mapping of the interaction landscape of a wide range of functional materials operating in aqueous solution, from wet adhesives to fuel cell membranes.
- Type
- Research Article
- Information
- MRS Bulletin , Volume 39 , Issue 12: Water at Functional Interfaces , December 2014 , pp. 1082 - 1088
- Copyright
- Copyright © Materials Research Society 2014
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