Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 9: Membranes and Interfaces

BP 9.5: Talk

Tuesday, February 26, 2008, 11:45–12:00, PC 203

Diffusion of nano-particles bound to model membranes — •Florian Rückerl, Lydia Woiterski, Josef Käs, and Carsten Selle — Universität Leipzig, Linnéstr. 5, 04103 Leipzig

The diffusive transport in membranes is an important process in cells, especially for signaling at the cell surface. In our investigations we compare the diffusive motion of different nano-particles (latex beads, quantum dots and quantum dots bound to lipids) in a variety of model membranes (monolayers, tethered bilayers and giant unilamellar vesicles). The model membranes,composed of ternary mixtures of lipids (DOPC, cholesterol and DPPC or Sphingomyelin), form liquid membranes and exhibit an ordered-disordered phase coexistence. Our aim is to elucidate the interactions of the membrane with the particles close to the border of such phase coexistence regions. The comparison of the systems enables to differentiate between the mechanisms that influence the diffusion, mainly electrostatic and hydrodynamic interactions. In monolayers the dipolar interaction is dominant leading to a confinement of the partially charged particle at the border of the domain. This transition from two- to one-dimensional diffusion is also dependent on the domain size, being most effective for small domains (R<1 µ m). A similar change can be observed for latex beads adsorbed to lipid vesicle, where dipolar interactions are considered only weak and short-ranged.

Thus, domain associated dimensional reduction might play a significant role in more physiological bilayer systems. This might be utilized by cellular systems in order to control membrane protein diffusion.