Buckling patterns in model membranes consisting of phospholipids and lipopolymers were quantitatively investigated using epi-fluorescence microscopy and AFM. Results show that increased concentrations of lipopolymers in the membrane enhanced the formation of buckled regions in the monolayer. Similarly, increasing cholesterol concentrations in a monolayer with low lipopolymer concentration also cause formation of buckling structures. By applying mean-field calculations of polymer-tethered membranes and thin film buckling theory of an Euler column, we are able to quantitatively link buckling structures and membrane elasticity. Our results demonstrate that cholesterol and lipopolymers induce buckles due to increased biaxial stress in the membrane. Intriguingly, no additional lipid monolayer was able to form on top of the buckling regions of the polymer-tethered monolayer containing poly(2-ethyl-2oxazoline) lipopolymers, thus forming a compartmentalized  polymer-tethered lipid bilayer. Our experiments demonstrate the fascinating materials properties of polymer-tethered membranes and reveal a complex interplay of their elastic, organizational, and dynamic properties.

Thin film buckling in polymer-tethered membranes

243rd National Meeting (2012)

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