Rough-smooth-rough dynamic interface growth in supported lipid bilayers

The role of lipid bilayer viscoelasticity and the substrate-bilayer interactions on the spreading behavior of supported phospholipid bilayer membranes is studied using fluorescence microscopy. Unlike the monotonic roughening observed on silica or in other dynamic interface growth systems, a unique rough-smooth-rough (RSR) interface transition occurred on chromium oxide with a roughness exponent of 0.45 +/- 0.04. This RSR transition is attributed to the elasticity of the lipid bilayer which is initially under compression due to surface interactions, and is well approximated by adding an elastic term to the quenched noise Edwards-Wilkinson equation. A phase diagram depicting the conditions necessary to observe RSR transitions in dynamic interface systems is derived, revealing the classes of dynamically evolving systems is broader than previously thought, and the viscoelastic nature of the lipid bilayer may play a role in supported membrane behavior.