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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: POSTERS Dynamics and Diffusion

CPP 15.2: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

On the diffusion of circular domains on a spherical vesicle — Pietro Tierno¹, Prajnaparamita Dhar², Ziad Khattari³, •Saeedeh Aliaskarisohi⁴, and Thomas Fischer⁴ — ¹Universitat de Barcelona — ²University of California Santa Barbara — ³Hashemite University, Zarqa, Jordan — ⁴University of Bayreuth

Tracking the motion of single, two or more lipid domains on a vesicle is a rheological technique allowing to measure surface shear viscosities of vesicular lipid phases. The ratio of surface to bulk viscosity defines a viscous length scale. Hydrodynamic interactions split the motion of the domains into different modes of diffusion. The measurability of surface shear viscosities from any mode of diffusion is limited to viscous length scales between the radius of the domains and the radius of the vesicle. The measurability of the surface shear viscosity results from the sensitivity of the diffusion to surface shear viscosities and from sufficient spatial resolution to resolve the diffusive motion. Switching between the various modes of diffusion is a trade between sensitivity gained and resolution lost by the hydrodynamic interactions leaving the measurability unchanged. Measurability drops with the number of domains making single-domain rheology the best technique to measure surface shear viscosities. Ultimately confinement of the domains to small vesicles renders measurements of surface rheological properties with domain tracking rheology impossible. Our results suggest that recent experiments on the diffusion of domains on liquid ordered vesicles need to be reanalyzed.