Slaved Diffusion in Phospholipid Bilayers

ORAL

Abstract

Dual-color fluorescence correlation spectroscopy (FCS) was employed to simultaneously investigate the translational diffusion of phospholipids in supported fluid bilayers and polymers which adsorb on these bilayers at incomplete surface coverage. It was found that the translational diffusion of phospholipids split into two populations due to polymer adsorption. A slow mode, whose magnitude was the same as that of adsorbed polymers, coexisted with a fast mode characteristic of naked lipid diffusion. Using 2-color fluorescence, cross-correlation between the diffusion of phospholipids and polymers suggested the plausible interpretation that polymer adsorption created nanodomains of lipid whose mobility was determined by the occluded area of the adsorbed polymer. That is, those lipids inside the nanodomains were enslaved by the adsorbed polymers and diffused collectively. Variations of the polymer molar mass showed that the slow mode of phospholipid diffusion varied inversely with molar mass of the adsorbate, as predicted by our notion of slaved diffusion. This work offers a new mechanism to explain how naonsized domains with reduced mobility arise in lipid membranes.

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Authors

  • Liangfang Zhang

    Dept. of Chemical \& Biomolecular Engineering, UIUC, Department of Chemical \& Biomolecular Engineering, UIUC

  • Steve Granick

    Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Departments of Physics, Chemistry, and Materials Science and Engineering, University of Illinois at Urbana-Champaign, University of Illinois at Urbana-Champaign, Dept. of Materials Science \& Engineering, of Physics, of Chemistry, and of Chemical \& Biomolecular Engineering, UIUC, Departments of Materials Science and Engineering, of Chemistry, of Physcis, University of Illinois, Department of Materials Science and Engineering, Chemistry, Physics, Chemical Engineering, University of Illinois at Urbana-Champaign, UIUC, Materials Science and Engineering Department, Department of Materials Science \& Engineering, of Chemistry, of Physics, and of Chemical \& Biomolecular Engineering, UIUC, Departments of Chemistry and of Material Science, University of Illinois