Nanomechanical Contrasts of Gel and Fluid Phase Supported Lipid Bilayers

Abstract

Lipid bilayers exhibit structural diversity that contributes to the complex properties of the cell membrane. We use interfacial force microscopy to correlate mechanical properties with the two-dimensional phase behavior of supported lipid bilayers (SLBs). Upon indentation by a 500 nm tungsten tip, a contrast in the mechanical response is observed for gel vs fluid phase SLBs. We measure the yield force and time scale for recovery for these films. Consistent with a gel phase, a DSPC SLB has a relatively high yield force and slow recovery. In the higher mobility fluid phase, a DLPC SLB has a lower yield force and completely recovers within the experimental time scale. Friction measurements offer further contrast between the two SLBs.