Phospholipid Bilayers as Biomembrane-like Barriers in Layer-by-Layer Polyelectrolyte Films

Abstract

Dipalmitoylphosphatidylcholine (DPPC) bilayer was created on the surface of an exponentially growing poly(glutamic acid)/poly(lysine) (PGA/PLL) layer-by-layer polyelectrolyte film. The lipid bilayer decreased the surface roughness of the polyelectrolyte film. The layer-by-layer construction of the polyelectrolyte film could be continued on the top of the DPPC layer. The lipid bilayer, however, formed a barrier in the interior of the polyelectrolyte film, which blocked the diffusion (a prerequisite for exponential growth) of the polyelectrolytes. Thus, a new growth regime started in the upper part of the polyelectrolyte film, which was added to embed the DPPC bilayer. The structure and the dynamics of the DPPC bilayer on the polyelectrolyte film surface remained similar to that of its hydrated multibilayers, except that the phase transition became wider. In the case of embedded DPPC bilayers, in addition, the phase-transition temperature also decreased. This is the result of interactions with the nonconcerted movements of the barrier-separated lower and higher parts of the polyelectrolyte film. Gramicidin A (GRA) as a model of lipid-soluble peptides and proteins was successfully incorporated into such DPPC films. The DPPC films, either with or without GRA, were remarkably stable; as many heating-cooling cycles to measure phase transition could be carried out without visible alterations as wanted.

Interaction of cysteine-rich cationic antimicrobial peptides with intact bacteria and model membranes

“…Planar supported bilayers were built up (Dufrene and Lee 2000;Pilbat et al 2007), or natural membranes isolated from bacteria and anchored to flat surfaces (Müller et al 2000;Végh et al 2011) were used as models of biological membranes of bacterial cells. The effect of different cationic antimicrobial peptides has already been studied on planar lipid bilayers of different compositions (Shaw et al 2008;Végh et al 2011).…”

Structural characterization of an elevated lipid bilayer obtained by stepwise functionalization of a self-assembled alkenyl silane film

“…5 The main drawback of solid supports is that typical distances between the membrane and the substrate range up to 1 nm, 6,7 which is generally not enough to prevent the denaturing of transmembrane proteins. 7 In the effort to space the membrane up from the silicon substrate polymeric cushion materials that can form hydrated thin films such as polyacrylamide, 8 dextran, 9 agarose, 10 polyethyleneimine, 11,12 cellulose derivatives, 13 and poly͑ethylene glycol͒, [15][16][17] as well as polyelectrolyte multilayers, 18,19 have been introduced prior to membrane deposition.…”

Vibrational spectroscopy for probing molecular-level interactions in organic films mimicking biointerfaces

“…Pilbat et al [139] reported a method to immobilize cell membrane bilayers of DPPC in LbL films of poly-(glutamic acid)/poly(lysine) (PGA/PLL). The film growth regime was altered by inserting a DPPC bilayer in between the polyelectrolyte bilayers because this DPPC bilayer blocked diffusion for the next PGA/PLL layers.…”