Local Membrane Mechanics of Pore-Spanning Bilayers

Mey, Ingo; Stephan, Milena; Schmitt, Eva K.; Müller, Martin; Amar, Martine Ben; Steinem, Claudia; Janshoff, Andreas

doi:10.1021/ja809165h

Cited by 102 publications

(203 citation statements)

References 27 publications

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“…51,52 Depending on the surface of the porous supports, the bilayer is formed via the rupture of large or giant unilamellar vesicles and painting of lipids dissolved in organic solvent (Figure 4a). 53 Such configurations are similar to the black lipid membrane in which planar lipid bilayers are formed across Teflon apertures with hole diameters of 0.1-1 mm. In contrast to the black lipid membrane, the substantially reduced pore size gives the resulting lipid bilayers long-term stability and compatibility with the automated and miniaturized electronic devices.…”

Section: Lipid-1d-nanostructure Hybridsmentioning

confidence: 79%

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Lipid-nanostructure hybrids and their applications in nanobiotechnology

Lee

Nam

2013

NPG Asia Mater

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Cell membranes contain a variety of lipids and functional proteins that offer active platforms that organize the membrane components into functional assemblies and perform biologically important reactions. The dynamic and complex nature of the membranes makes them attractive materials, but at the same time, researchers report substantial experimental uncertainty in controlling the membrane reactions and extracting valuable information. The fascinating new structures and properties of nanomaterials could be utilized in addressing aforementioned issues, and the design and synthesis of lipid-nanostructure hybrids could be beneficial to the research areas in lipid-membrane biotechnology and nanobiotechnology. These hybrid structures possess dimensions that are comparable to that of biological molecules and structures and physicochemical properties that arise from both lipids and nanomaterials. Therefore, lipid-nanostructure hybrids offer additional options for control of the synthesized structures, provide new insight in understanding nanostructures and biological systems and allow the mimicking of functional subcellular membrane components and monitoring of the membrane-associated reactions in a highly sensitive and controllable manner. In this review, we present recent advances in the synthesis of various lipid-nanostructure hybrids and the application of these structures in biotechnology and nanotechnology. We further describe the scientific and practical applications of lipid-nanostructure hybrids for detecting membrane-targeting molecules, interfacing nanostructures with live cells and creating membrane-mimicking platforms to investigate various intercellular processes.

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Section: Lipid-1d-nanostructure Hybridsmentioning

confidence: 79%

“…The mechanical behaviors of pore-spanning lipid bilayers were scrutinized by local indentation experiments with an atomic force microscopy tip (Figure 4c). 53 The responses of the membranes were fully elastic, but the origins of these linear responses were varied depending on the preparation method and lipid composition. …”

Section: Lipid-1d-nanostructure Hybridsmentioning

confidence: 99%

Lipid-nanostructure hybrids and their applications in nanobiotechnology

Lee

Nam

2013

NPG Asia Mater

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“…Ursell et al (13) observed a repulsion of domains in deflated GUVs, caused by the induction of membrane curvature between the l o domains. In the case of PSMs, the rather large lateral membrane tension of about 1 mN·m −1 (23,24,32) prevents the induction of a 3D structure in the center of the PSM, although it does not significantly alter phase separation (33,34). This trait allows the l o domains to merge, leading to only one mobile domain in each PSM.…”

Section: Resultsmentioning

confidence: 99%

Size and mobility of lipid domains tuned by geometrical constraints

Schütte

Mey

Enderlein

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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In the plasma membrane of eukaryotic cells, proteins and lipids are organized in clusters, the latter ones often called lipid domains or "lipid rafts." Recent findings highlight the dynamic nature of such domains and the key role of membrane geometry and spatial boundaries. In this study, we used porous substrates with different pore radii to address precisely the extent of the geometric constraint, permitting us to modulate and investigate the size and mobility of lipid domains in phase-separated continuous pore-spanning membranes (PSMs). Fluorescence video microscopy revealed two types of liquid-ordered (l o ) domains in the freestanding parts of the PSMs: (i) immobile domains that were attached to the pore rims and (ii) mobile, round-shaped l o domains within the center of the PSMs. Analysis of the diffusion of the mobile l o domains by video microscopy and particle tracking showed that the domains' mobility is slowed down by orders of magnitude compared with the unrestricted case. We attribute the reduced mobility to the geometric confinement of the PSM, because the drag force is increased substantially due to hydrodynamic effects generated by the presence of these boundaries. Our system can serve as an experimental test bed for diffusion of 2D objects in confined geometry. The impact of hydrodynamics on the mobility of enclosed lipid domains can have great implications for the formation and lateral transport of signaling platforms. diffusion | hydrodynamics | lipid rafts | membrane dynamics | pore-spanning membranes T he plasma membrane of eukaryotic cells compartmentalizes into lipid domains that enable the selective recruitment of specific proteins (1, 2). These domains are an important feature for regulating biological functions such as apical sorting, protein trafficking, and the clustering of proteins during signaling. The most prominent concept for membrane organization, the lipid raft theory, relates lipid phase separation [driven by interactions between cholesterol (chol), sphingolipids, and saturated phospholipids] to membrane protein partitioning and regulation (2, 3). Lipid domains such as rafts are difficult to observe in biological membranes due to their small size and dynamic nature (4). To understand the phase separation phenomena and the dynamics of lipid domains, the phase behavior of giant plasma membrane-derived vesicles (5, 6) as well as ternary model membranes containing two phospholipid species and chol have been investigated extensively in the last decade. In these model membranes, lipid phase separation between liquid-ordered (l o ) and liquid-disordered (l d ) phases is readily observed at low temperature (7-9). These raft-like domains grow several micrometers in size in giant unilamellar vesicles (GUVs) (7), while their mobility is preserved, whereas lipid domains in supported lipid bilayers are smaller but are largely immobile and do not form energy-minimized round shapes (10). Explanations for the size difference of lipid domains in native plasma membranes and model membranes ran...

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“…This is presumably a result of the fact that pore-spanning membranes are already pre-stressed even before lipids are removed. [21] The prestress facilitates their rupture if the cholesterol surface concentration is reduced. This observation is different from what has been reported by Giocondi et al, [22] who found stable holes in solid supported membranes upon lipid depletion, which indicates the minor mobility of the lipids on the support.…”

Section: Modulation Of the Phase Separation In Pore-suspending Membranesmentioning

confidence: 99%

Creating and Modulating Microdomains in Pore‐Spanning Membranes

et al. 2011

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The architecture of the plasma membrane is not only determined by the lipid and protein composition, but is also influenced by its attachment to the underlying cytoskeleton. Herein, we show that microscopic phase separation of "raft-like" lipid mixtures in pore-spanning bilayers is strongly determined by the underlying highly ordered porous substrate. In detail, lipid membranes composed of DOPC/sphingomyelin/cholesterol/Gb(3) were prepared on ordered pore arrays in silicon with pore diameters of 0.8, 1.2 and 2 μm, respectively, by spreading and fusion of giant unilamellar vesicles. The upper part of the silicon substrate was first coated with gold and then functionalized with a thiol-bearing cholesterol derivative rendering the surface hydrophobic, which is prerequisite for membrane formation. Confocal laser scanning fluorescence microscopy was used to investigate the phase behavior of the obtained pore-spanning membranes. Coexisting liquid-ordered- (l(o)) and liquid-disordered (l(d)) domains were visualized for DOPC/sphingomyelin/cholesterol/Gb(3) (40:35:20:5) membranes. The size of the l(o)-phase domains was strongly affected by the underlying pore size of the silicon substrate and could be controlled by temperature, and the cholesterol content in the membrane, which was modulated by the addition of methyl-β-cyclodextrin. Binding of Shiga toxin B-pentamers to the Gb(3)-doped membranes increased the l(o)-phase considerably and even induced l(o)-phase domains in non-phase separated bilayers composed of DOPC/sphingomyelin/cholesterol/Gb(3) (65:10:20:5).

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Local Membrane Mechanics of Pore-Spanning Bilayers

Cited by 102 publications

References 27 publications

Lipid-nanostructure hybrids and their applications in nanobiotechnology

Lipid-nanostructure hybrids and their applications in nanobiotechnology

Size and mobility of lipid domains tuned by geometrical constraints

Creating and Modulating Microdomains in Pore‐Spanning Membranes

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