Polymer Cushions in Supported Phospholipid Bilayers Reduce Significantly the Frictional Drag between Bilayer and Solid Surface

Abstract

The reduction of fluid lecithin bilayer-substrate coupling by the presence of a hydrophilic polymer cushion in spherical supported bilayers of dipalmitoylphosphatidylcholine (DPPC) has been studied by measuring the lecithin molecular order and lateral diffusion using a deuterium NMR relaxation method. We obtained for both monolayers of the supported bilayer a lateral diffusion coefficient (D ) 13.5 × 10 -12 m 2 /s at 55 °C) similar to that measured previously in the outer monolayer of a supported bilayer on a bare silica surface, indicating that the presence of the polymer cushion can indeed largely eliminate the slow down effect of the solid surface on the bilayer dynamics. Moreover, we found that the polymer cushion rendered the molecular order of the lipids identical to that measured for multilamellar bilayer vesicles (MLV). A comparison of the measured D values with those obtained for oriented planar multilayer stacks of DPPC strongly suggests that lateral diffusion in these systems is still a factor of 2 faster than that of single bilayers on a support.

4 Electrochemistry of Biomimetic Membranes

“…124,125 Several theoretical and experimental investigations of water near polar hydrophilic surfaces suggest that it is more ordered than bulk water, with higher viscosity and lower dielectric constant. 126,127 In accordance with these predictions, the characteristics of the lipid bilayer have been found to be structurally coupled with the support properties, such as its charge 128 , wettability 129 and topography 130 . Frictional or electro-static coupling between the support and at least the proximal leaflet of the lipid bilayer may induce undesirable asymmetries in compositional, structural, mechanical and dynamic properties of the lipid bilayer.…”

HrpZPsph from the plant pathogen Pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore invitro

“…SIL), which allow measurement of protein binding to membranes (31). Because the lipid molecules are not covalently linked to the support and are separated by an ultrathin layer of water molecules, this material has characteristics reminiscent of the lipid bilayer of biological membranes (38). When purified recombinant HrpZ Psph was added to TRANSIL beads coated with POPC͞POPE (80: 20), approximately 80% of the protein applied was found to bind (Fig.…”

Flow-Mediated On-Surface Reconstitution of G-Protein Coupled Receptors for Applications in Surface Plasmon Resonance Biosensors

“…12) are needed. It is also advantageous to build reconstituted membranes on polymer hydrogels, which allows essentially undisturbed lipid bilayer dynamics (21).…”