Polymer-supported bilayer on a solid substrate

Spinke, J.; Yang, Jianling; Wolf, Heiko; Liley, Martha; Ringsdorf, Helmut; Knoll, Wolfgang

doi:10.1016/s0006-3495(92)81742-3

Cited by 196 publications

(190 citation statements)

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“…To provide more biologically relevant architectures, molecular assemblies of increased complexity and longterm stability have been tested, including a partial chemical fixation of the membrane's lipids to the underlying polymeric substrate. 7,14,18,19 However, the construction of such "asymmetric" tethered supported membranes is not always straightforward, and each particular …”

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confidence: 99%

“…The most versatile approach appears to be vesicle fusion onto polymer-supported lipid monolayers previously prepared by LB transfer or self-assembly ( Figure 1). 16 In general, this allows for both (a) a partial fixation of the inner (proximal) lipid layer to the underlying polymer gel and (b) the reconstitution of integral membrane proteins into the supported membrane.Adopting a concept first introduced by Spinke et al, 14 we have recently synthesized and studied lipopolymers, which are comprised of an acrylamide backbone modified with lipid side chains (DMPE) and a disulfide moiety for the chemisorption to gold substrates (Figure 1). 20-22 After adsorption onto gold or mica surfaces they form a hydrophilic, water-swellable polymer cushion underneath a layer of lipid side chains.…”

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Formation of Tethered Supported Bilayers by Vesicle Fusion onto Lipopolymer Monolayers Promoted by Osmotic Stress

et al. 2000

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Lipid bilayer systems have been used extensively to study the structure and function of biomembranes including molecular recognition, permeation, adhesion, and fusion. 1-5 Further interest arises from their potential use as biosensors.6 , 7 While classical black lipid bilayer membranes are highly suitable as such model systems, they suffer from their limited long-term stability. 1 Additionally, to apply the broad range of surface sensitive experimental techniques developed in recent years for the characterization of ultrathin films, it is often necessary to immobilize lipid bilayers on solid supports. However, lateral fluidity of the lipid membrane is governed by the physical and chemical properties of the solid substrate. Thus, bilayer membranes prepared by the Langmuir-Blodgett (LB) technique or by vesicle fusion directly onto solid substrates are often polycrystalline or amorphous, and lateral lipid mobility within the membrane is restricted. While on hydrophilic oxidized silicon or glass a water layer (~1 nm thick) is formed which allows for free diffusion of phospholipid molecules (but not membrane-spanning proteins) within the bilayer,8 -10 on most other metals and metal oxides, lipid mobility is strongly suppressed.11 , 12 To preserve the membrane's natural properties, one promising approach is to rest it on a water-swellable (hydrophilic) polymer or polyelectrolyte cushion which can act as a deformable and mobile substrate6 , 13 , 14 like the cytoskeletal support in living cells. Such softly supported lipid bilayers can, in principle, exist in an entirely fluid state, nearly undisturbed by the presence of the supporting polymer gel which provides an aqueous compartment between the solid substrate and the membrane. In our recent work, we have studied DMPC bilayers on a highly branched cationic polymer (polyethylenimine, PEI). Important structural information about these polymer-supported bilayer systems formed by various preparation methods was provided by neutron scattering experiments.15 , 16 Furthermore, measuring the intermembrane interaction forces using the surface forces apparatus (SFA) technique has shown the effect of fluidity on membrane functionality.17These physisorbed, polymer-supported bilayers are only the first step in the approach of creating artificial biomembranes that more closely resemble living cells. To provide more biologically relevant architectures, molecular assemblies of increased complexity and longterm stability have been tested, including a partial chemical fixation of the membrane's lipids to the underlying polymeric substrate. 7,14,18,19 However, the construction of such "asymmetric" tethered supported membranes is not always straightforward, and each particular NIH Public Access Author ManuscriptLangmuir. Author manuscript; available in PMC 2010 October 13. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript system needs to be optimized. The most versatile approach appears to be vesicle fusion onto polymer-supported lipid monolayers previously prep...

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confidence: 99%

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Formation of Tethered Supported Bilayers by Vesicle Fusion onto Lipopolymer Monolayers Promoted by Osmotic Stress

et al. 2000

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“…calculated with constant refractive index, the "adlayer thickness" becomes a measure of molecule density; only at close packing it can be interpreted in terms of molecular dimensions. According to published data obtained with well-defined model systems, n = 1.45 is a reasonable value for the refractive index of lipids in a fluid state and adsorbed proteins (Lang et al, 1992(Lang et al, , 1994Spinke et al, 1992Spinke et al, , 1993Reiter et al, 1993; Terrettaz et ai., 1993) (and references therein).5 For lipids and fatty acid salts in a crystalline state, refractive indices in the range of n = 1.5 seem more appropriate (Swalen, 1986;Kooyman & Krull, 1991;Schmidt et al, 1992). But in our experiments, a crystalline state of lipids on the waveguide can be excluded (see below).…”

Section: Choice Of Refractive Index For Optical Measurementsmentioning

confidence: 85%

Covalent attachment of functionalized lipid bilayers to planar waveguides for measuring protein binding to biomimetic membranes

et al. 1995

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A new method is presented for measuring sensitively the interactions between ligands and their membrane-bound receptors in situ using integrated optics, thus avoiding the need for additional labels. Phospholipid bilayers were attached covalently to waveguides by a novel protocol, which can in principle be used with any glass-like surface.In a first step, phospholipids carrying head-group thiols were covalently immobilized onto Si02-Ti02 waveguide surfaces. This was accomplished by acylation of aminated waveguides with the heterobifunctional crosslinker N-succinimidyl-3-maleimidopropionate, followed by the formation of thioethers between the surface-grafted maleimides and the synthetic thiolipids. The surface-attached thiolipids served as hydrophobic templates and anchors for the deposition of a complete lipid bilayer either by fusion of lipid vesicles or by lipid self-assembly from mixed lipid/detergent micelles. The step-by-step lipid bilayer formation on the waveguide surface was monitored in situ by an integrated optics technique, allowing the simultaneous determination of optical thickness and one of the two refractive indices of the adsorbed organic layers. Surface coverages of 50-60% were calculated for thiolipid layers. Subsequent deposition of POPC resulted in an overall lipid layer thickness of 45-50 A , which corresponds to the thickness of a fluid bilayer membrane.Specific recognition reactions occurring at cell membrane surfaces were modeled by the incorporation of lipidanchored receptor molecules into the supported bilayer membranes. (1) The outer POPC layer was doped with biotinylated phosphatidylethanolamine. Subsequent specific binding of streptavidin was optically monitored. (2) A lipopeptide was incorporated in the outer POPC monolayer. Membrane binding of monoclonal antibodies, which were directed against the peptide moiety of the lipopeptide, was optically detected. The specific antibody binding correlated well with the lipopeptide concentration in the outer monolayer.

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“…Spinke et al 227,228 described a polymer-supported lipid bilayer anchored to gold. These authors used a methacrylic terpolymer consisting of a hydrophilic main chain that acts as a spacer, a disulfide unit that anchors the polymer to the gold surface, and a hydrophobic lipid-like part that forms a first lipid monolayer upon self-assembly.…”

Section: Polymer-cushioned Bilayer Lipid Membranes (Pblms)mentioning

confidence: 99%