Journal of Physical Chemistry B 2009-07-09

Nanomechanical contrasts of gel and fluid phase supported lipid bilayers.

M P Goertz, B L Stottrup, J E Houston, X-Y Zhu

Index: J. Phys. Chem. B 113(27) , 9335-9, (2009)

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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.