Metric between buckling structures and elastic properties in physisorbed polymer-tethered lipid monolayers

Abstract

The current study reports the use of buckling structures as a measure of film elasticity on physisorbed, solid-supported polymer-tethered lipid monolayers consisting of phospholipids and poly(ethylene glycol) (PEG) lipopolymers. These monolayer systems, built using the Langmuir–Blodgett (LB) technique, exhibit buckles over a wide range of lipopolymer concentrations. Systematic quantitative analysis of the buckling structures using epifluorescence microscopy and atomic force microscopy reveals that increased lipopolymer concentrations are associated with higher area fractions of buckling regions. Quantitative analyses of buckling profiles show, furthermore, that enhanced lipopolymer concentrations lead to increased buckling widths without notably altering buckling amplitude. On the basis of these experimentally determined buckling parameters, we are able to derive a metric between elastic properties and buckling structures in the polymer-tethered lipid monolayer system. This is achieved by combining mean-field calculations of elastic properties of polymer-tethered lipid membranes with buckling theory of an Euler column. Our findings are significant because they provide new insight into the fascinating materials properties of polymer-lipid supramolecular assemblies and represent a tool for the characterization of elastic properties in complex biomembrane-mimicking film architectures with buckling structures.