Controllable occurrence of free-standing lipid membranes on nanograting structured supports
Journal
ACS Applied Materials and Interfaces
Journal Volume
6
Journal Issue
15
Pages
12261-12269
Date Issued
2014
Author(s)
Abstract
Supported lipid bilayers (SLBs) have been widely used to study protein-lipid membrane interactions because their planar geometry is suitable for many surface analysis tools. However, the friction coupling between the support and the membrane can influence the properties of biomolecules in the membrane. Many studies have attempted to span SLBs over nanostructured supports to create free-standing regions in SLBs for biosensor applications. However, membranes following the support surface contour are more frequently observed than are free-standing membranes on structured supports, indicating that the parameter range suitable for formation of free-standing SLBs might be narrow and more information is necessary to understand the required conditions. The objective of this study was to estimate the system energies of free-standing and contour-following membrane states and determine which state is the most energetically favorable under various conditions. For a lipid membrane preferring to stay close to the support, an energy reward occurs when they are in close proximity; however, increasing the contact area on a structured surface can result in an energy penalty because of the bending of the lipid bilayer. Whether the energy reward or the energy penalty dominates could determine the membrane state. We used the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the Helfrich bending theory to relate the energy sizes to experimentally controllable parameters. We experimentally examined whether the membrane state followed the model prediction when we used various buffer ionic strengths, various lipid types, and nanograting supports with three different geometries. Because it is difficult to observe the experimental membrane state directly at the nanoscale, we developed a method to use the fluorescence recovery shape change after photobleaching to distinguish experimental membrane states at the micrometer scale. Our experimental results closely matched the theoretical predictions, suggesting that the developed model can be used to predict suitable conditions for formation of free-standing bilayers on nanostructured solid supports. ? 2014 American Chemical Society.
Subjects
contour-following
extended DLVO theory
free-standing
nanograting structured support
supported lipid bilayers
trench-spanning membranes
SDGs
Type
journal article