Direct Photochemical Patterning and Refunctionalization of Supported Phospholipid Bilayers

Yee, Chanel K.; Amweg, Meri L.; Parikh, Atul N.

doi:10.1021/ja047714k

Cited by 77 publications

(82 citation statements)

References 65 publications

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“…While lipids could diffuse within the individual corrals, the long-range diffusion was interrupted at random edges, leading to segmentation of the surface into corrals that were connected to each other, but separate from other groups. One explanation of this bilayer fracture is that exposure of the bilayers to light induces contraction or loss of bilayer material, a process that has been described using UV wavelengths 31,32 ; we speculate that photobleaching of the Texas Red fluorophores at their respective excitation wavelength may produce a similar effect here. Alternatively, local heating of the barriers may be responsible for these effects.…”

Section: Barrier Composition Influences Bilayer Structurementioning

confidence: 63%

Non-Brownian Diffusion of Membrane Molecules in Nanopatterned Supported Lipid Bilayers

et al. 2008

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Molecules associated with the outer surface of living cells exhibit complex, non-Brownian patterns of diffusion. In this report, supported lipid bilayers were patterned with nanoscale barriers to capture key aspects of this anomalous diffusion in a controllable format. First, long-range diffusion coefficients of membrane-associated molecules were significantly reduced by the presence of the barriers, while short-range diffusion was unaffected. Second, this modulation was more pronounced for large molecular complexes than for individual lipids. Surprisingly, the quantitative effect of these barriers on long-range lipid diffusion could be accurately simulated using a simple, continuum-based model of diffusion on a nanostructured surface; we thus describe a metamaterial that captures the properties of the outer membrane of living cells.The outer surface of cells presents a complex, nanostructured, yet fluid environment that controls the movement of signaling proteins. The lateral movement of many membrane biomolecules, including transmembrane or tethered proteins as well as lipids themselves, can be interpreted as being free and isotropic within compartments of the cell membrane measuring tens to hundreds of nanometers in scale [1][2][3][4][5][6] . These compartments are delineated by semipermeable barriers that arise from interactions between the plasma membrane, underlying cytoskeleton, and associated proteins [6][7][8] . Fluctuations in these structures allow biomolecules to occasionally cross between compartments, allowing long-range, but comparatively slow, transport over the cell surface. More formally, transport along the membrane is an anomalous, non-Brownian process that can be characterized by two diffusion coefficients, one that describes short-range motion within an individual compartment and a second, smaller, effective diffusion coefficient that is associated with long-range motion over many barriers. The extent to which these values differ is dependent on the spacing and properties of the barriers as well as the diffusing molecule. Emerging models suggest significant impacts of this behavior on cell signaling 2, 9, 10 , but experimental systems for testing these hypotheses are not widely available. In this report, we capture this anomalous diffusion by nanopatterning supported lipid bilayers with barriers to lipid diffusion using a geometry that captures the semipermeable nature of those posed to be present in living cells. As is posed by models of these interactions, we aim to gain control over long-range diffusion, while maintaining local, isotropic diffusion associated with a membrane in the absence of such barriers. We demonstrate that these nanopatterned barriers give rise to different short-and long-range diffusion coefficients of lipids and membrane-associated proteins, and provide a quantitative model of this diffusion that suggests specific aspects of membrane structure at the sub-micrometer level. The basic substrate supported lipid bilayer system consists of a phospholipid membrane...

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Section: Barrier Composition Influences Bilayer Structurementioning

confidence: 63%

Non-Brownian Diffusion of Membrane Molecules in Nanopatterned Supported Lipid Bilayers

et al. 2008

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“…These were compared to membranes generated through small unilamellar vesicle fusion according to standard protocols. 12,37,41,42 A visual evaluation of the membranes produced by solvent exchange and vesicle fusion shows that both are homogeneous ͓Figs. 7͑a͒ and 7͑d͔͒.…”

Section: E Diffusion Measurementsmentioning

confidence: 99%

“…The measured diffusion constant consistent with the value 2.0Ϯ 0.4 m 2 s −1 obtained for a DMPC bilayer prepared by the vesicle fusion technique. 41,42 For comparison, the reader is reminded that in a free lipid bilayer, the diffusion constant of DMPC lies at about 0.5-5 m 2 s −1 at room temperature. 41 For this protocol, the washing steps to remove excess alcohol are important; otherwise, the presence of a significant amount of residual alcohol would tend to increase membrane fluidity as a result of its H-bonding with the hydrocarbon chains, which then leads to a decrease its conformation order.…”

Section: E Diffusion Measurementsmentioning

confidence: 99%

Controlled solvent-exchange deposition of phospholipid membranes onto solid surfaces

Hohner¹,

David²,

Rädler³

2010

Biointerphases

114

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“…[1][2][3][4][5] Phosphocholine (PC) lipids deposited on silica (SiO2) is the most commonly used system since PC liposomes readily fuse with silica under physiological conditions. [6][7][8][9][10][11] In addition, PC liposomes are zwitterionic and highly biocompatible. A thin water layer (~1 nm) separates the PC headgroup from the silica surface to achieve a mobile bilayer.…”

Section: Introductionmentioning

confidence: 99%

A Stable Lipid/TiO₂ Interface with Headgroup-Inversed Phosphocholine and a Comparison with SiO₂

Wang

Liu

2015

J. Am. Chem. Soc.

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Zwitterionic phosphocholine (PC) lipids are highly biocompatible, representing a major component of the cell membrane. A simple mixing of PC liposomes and silica (SiO2) surface results in liposome fusion with the surface and formation of supported lipid bilayers. However, the stability of this bilayer is relatively low since adsorption is based mainly on weak van der Waals force. PC lipids strongly adsorb by TiO2 via chemical bonding between the lipid phosphate. The lack of fusion on TiO2 is attributable to the steric effect from the choline group in PC. In this study, inverse-phosphocholine lipids (CP) are used, directly exposing the phosphate.Using a calcein leakage assay and cryo-TEM, fusion of CP liposome with TiO2 is demonstrated.The stability of this supported bilayer is significantly higher than that of the PC/SiO2 system as indicated by washing the membrane under harsh conditions. Adsorption of CP liposomes by TiO2 is inhibited at high pH. Interestingly, the CP liposome cannot fuse with silica surface due to a strong charge repulsion. This study demonstrates an interesting interplay between soft matter surface and metal oxides. By tuning the lipid structure, it is possible to rationally control the interaction force. This study provides an alternative system for forming stable supported bilayers on TiO2, and represents the first example of interfacing inverse lipids with inorganic surfaces.

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Direct Photochemical Patterning and Refunctionalization of Supported Phospholipid Bilayers

Cited by 77 publications

References 65 publications

Non-Brownian Diffusion of Membrane Molecules in Nanopatterned Supported Lipid Bilayers

Non-Brownian Diffusion of Membrane Molecules in Nanopatterned Supported Lipid Bilayers

Controlled solvent-exchange deposition of phospholipid membranes onto solid surfaces

A Stable Lipid/TiO₂ Interface with Headgroup-Inversed Phosphocholine and a Comparison with SiO₂

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Direct Photochemical Patterning and Refunctionalization of Supported Phospholipid Bilayers

Cited by 77 publications

References 65 publications

Non-Brownian Diffusion of Membrane Molecules in Nanopatterned Supported Lipid Bilayers

Non-Brownian Diffusion of Membrane Molecules in Nanopatterned Supported Lipid Bilayers

Controlled solvent-exchange deposition of phospholipid membranes onto solid surfaces

A Stable Lipid/TiO2 Interface with Headgroup-Inversed Phosphocholine and a Comparison with SiO2

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A Stable Lipid/TiO₂ Interface with Headgroup-Inversed Phosphocholine and a Comparison with SiO₂