| 1. |
- Czolkos, Ilja, 1980, et al.
(författare)
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Controlled formation and mixing of two-dimensional fluids
- 2007
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:7, s. 1980-1984
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a novel technique for the controlled spreading and mixing of lipid monolayers from multilamellar precursors on surfaces covered by the hydrophobic epoxy resin SU-8. The lipid spreads as a monolayer as a result of the high surface tension between SU-8 and the aqueous environment. A micropatterned device with SU-8 lanes, injection pads, and mixing regions, surrounded by hydrophilic Au, was constructed to allow handling of lipid films and to achieve their mixing at controlled stoichiometry. Our findings offer a new approach to dynamic surface functionalization and decoration as well as surface-based catalysis and self-assembly.
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| 2. |
- Davidson, M., et al.
(författare)
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Fluid mixing in growing microscale vesicles conjugated by surfactant nanotubes
- 2005
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 127:4, s. 1251-1257
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Tidskriftsartikel (refereegranskat)abstract
- This work addresses novel means for controlled mixing and reaction initiation in biomimetic confined compartments having volume elements in the range of 10-12 to 10-15 L. The method is based on mixing fluids using a two-site injection scheme into growing surfactant vesicles. A solid-state injection needle is inserted into a micrometer-sized vesicle (radius 5-25 μm), and by pulling on the needle, we create a nanoscale surfactant channel connecting injection needle and the vesicle. Injection of a solvent A from the needle into the nanotube results in the formation of a growing daughter vesicle at the tip of the needle in which mixing takes place. The growth of the daughter vesicle requires a flow of surfactants in the nanotube that generates a flow of solvent B inside the nanotube which is counterdirectional to the pressure-injected solvent. The volume ratio ψ between solvent A and B inside the mixing vesicle was analyzed and found to depend only on geometrical quantities. The majority of fluid injected to the growing daughter vesicle comes from the pressure-based injection, and for a micrometer-sized vesicle it dominates. For the formation of one daughter vesicle (conjugated with a 100-nm radius tube) expanded from 1 to 200 μm in radius, the mixing ratios cover almost 3 orders of magnitude. We show that the system can be expanded to linear strings of nanotube-conjugated vesicles that display exponential dilution. Mixing ratios spanning 6 orders of magnitude were obtained in strings of three nanotube-conjugated micrometer-sized daughter vesicles.
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| 3. |
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| 4. |
- Gözen, Irep, 1980, et al.
(författare)
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Repair of large area pores in supported double bilayers
- 2013
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 9:10, s. 2787-2792
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Tidskriftsartikel (refereegranskat)abstract
- We describe an experimental system where we can generate, and subsequently close, multiple large membrane ruptures in supported double bilayers. We show in this study for the first time that large membrane pores (similar to 10-150 mu m in size) in flat phospholipid vesicles can be reduced in size or completely closed by a pore edge tension driven area reduction mechanism. We can dynamically control the membrane tension of a flat giant unilamellar vesicle and its interplay with the surface adhesion to a solid support. Adhesion to the support surface causes increased membrane tension, which eventually relaxes by the formation of several pores in the membrane. We show that the tension propagation time tau(max) is exceptionally long in this system, which allows for simultaneous opening of multiple pores. The pores can be stabilized by Ca2+-mediated pinning sites in the interior of the flat giant unilamellar vesicle. After pore formation followed by pinning, we depleted Ca2+ ions resulting in removal of pinning and relaxation of membrane tension. This allows the pore to close, driven by the pore edge tension.
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| 5. |
- Gözen, Irep, 1980, et al.
(författare)
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Thermal migration of molecular lipid films as a contactless fabrication strategy for lipid nanotube networks
- 2013
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Ingår i: Lab on a Chip - Miniaturisation for Chemistry and Biology. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 13:19, s. 3822-3826
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the contactless generation of lipid nanotube networks by means of thermally induced migration of flat giant unilamellar vesicles (FGUVs), covering micro-scale areas on oxidized aluminum surfaces. A temperature gradient with a reach of 20 mm was generated using a focused IR laser, leading to a surface adhesion gradient, along which FGUVs could be relocated. We report on suitable lipid-substrate combinations, highlighting the critical importance of the electrostatic interactions between the engineered substrate and the membrane for reversible migration of intact vesicles.
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| 6. |
- Karlsson, Roger, 1975, et al.
(författare)
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Chemical analysis in nanoscale surfactant networks
- 2006
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 78:17, s. 5960-5968
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Lobovkina, Tatsiana, 1975, et al.
(författare)
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Formation and release of circular lipid nanotubes
- 2008
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 4:3, s. 467-470
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Tidskriftsartikel (refereegranskat)abstract
- A method for formation of circular lipid nanotubes based on manipulation of nanotube-vesicle networks is presented.
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| 8. |
- Lobovkina, Tatsiana, 1975, et al.
(författare)
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Zipper dynamics of surfactant nanotube Upsilon junctions
- 2006
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 97:18
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the formation of Y junctions in surfactant nanotubes connecting vesicles. Based on experimental observations of the surfactant flow on the nanotubes, we conclude that a Y junction propagates with a zipperlike mechanism. The surfactants from two nanotube branches undergo 11 mixing at the junction, and spontaneously form the extension of the third nanotube branch. Taking into account the tension driven surfactant flow, we develop a model for the Y junction dynamics that is in quantitative agreement with the experimental data.
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| 9. |
- Stepanyants, Natalia, 1986, et al.
(författare)
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Spontaneous shape transformation of free-floating lipid membrane nanotubes
- 2013
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 9:21, s. 5155-5159
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Tidskriftsartikel (refereegranskat)abstract
- Freely floating lipid nanotubes, up to several hundred micrometers long, were found to spontaneously contract in length, and eventually transform into stomatocyte-like structures. This transformation was largely driven by the high curvature energy. The nanotubes equilibrate their membrane leaflet areas, by folding into tubular stomatocyte-like structures without any significant volume change, but require a substantial interleaflet lipid transport rate, estimated to be as high as 0.01-0.001 s(-1). The rate of transformation was dependent on the fluorescent membrane stain used, and nanotubes labelled with a water-soluble styryl dye, FM1-43, transformed approximately five-fold faster than nanotubes labelled with the phospholipid conjugated dye Texas Red DHPE.
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| 10. |
- Tokarz, Michal, 1976, et al.
(författare)
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Electrophoretic transport of latex particles in lipid nanotubes
- 2007
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 23:14, s. 7652-7658
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Tidskriftsartikel (refereegranskat)abstract
- Lipid vesicles can be connected by membrane nanotubes to build networks with promising bioanalytical properties. Here we characterize electrophoretic transport in such membrane tubes, with a particular eye to how their soft-material nature influences the intratube migration. In the absence of field, the tube radius is 110 +/- 26 nm, and it remains in this range during electrophoresis even though the applied electric field causes a slight decrease in the tube radius (similar to 6-11%). The electrophoretic velocity of the membrane wall (labeled with quantum dots) varies linearly with the field strength. Intratube migration is studied with latex spheres of radii 15, 50, 100, and 250 nm. The largest particle size does not enter the tube at fields strengths lower than 1250 V/m because the energy cost for expanding the tube around the particles is too high. The smaller particles migrate with essentially the same velocity as the membrane at low fields. Above 250 V/cm, the 15 nm particles exhibit an upward deviation from linear behavior and in fact migrate faster than in free solution whereas the 100 nm particles deviate downward. We propose that these nonlinear effects arise because of lipid adsorption to the particles (dominating for 15 nm particles) and a pistonlike compression of the solvent in front of the particles (dominating for 100 nm). As expected from such complexities, existing theories for a sphere migrating in a rigid-wall cylinder cannot explain our velocity results in lipid nanotubes.
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