Brillouin scattering of lipid membranes

Abstract
The lamellar phases of lipids undergo several structural phase transitions, between a two dimensional crystalline packing and the fluid-like state [1]. High frequency elastic properties of oriented multilamellar dimyristoyl-phosphatidylcholine (DMPC) were investigated by means of Brillouin scattering. It turns out that the hypersound velocities are highly sensitive to the structural changes due to the lamellar phase transitions. The obvious structural anisotropy of the membrane stacks results in fact in a rather small elastic anisotropy as seen by the Brillouin measurements. The results are interpreted in terms of a simple effective medium model for regularly layered composite.