| 1. |
- Sott, Kristin, 1974, et al.
(författare)
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Micropipet Writing Technique for Production of Two-Dimensional Lipid Bilayer Nanotube-Vesicle Networks on Functionalized and Patterned Surfaces
- 2003
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 19:9, s. 3904-3910
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Tidskriftsartikel (refereegranskat)abstract
- We present a micropipet-assisted writing technique for formation of two-dimensional networks of phospholipid vesicles and nanotubes on functionalized and patterned substrates. The substrates are patterned with vesicle-adhesive circular spots (5-7.5 µm in diameter) consisting of a basal layer of biotin on gold and an apical coating of NeutrAvidin in a sandwich manner. The area surrounding the adhesive spots is coated with a phosphatidylcholine bilayer membrane, preventing protein and liposome adhesion. Networks were formed by aspirating a biotin-functionalized giant unilamellar or multilamellar liposome (5-50 µm in diameter) into a ~3 µm inner diameter borosilicate glass micropipet. By using a pressurized-air microejection system, a portion of the liposome is then ejected back into the solution while forming a first vesicle ~3 µm in diameter. This vesicle is placed on an adhesive spot. When the micropipet is moved, a nanotube connection is formed from the first vesicle and is pulled to the next adhesive spot where a second vesicle is ejected. This procedure can then be repeated until the lipid material is consumed in the pipet. The method allows for formation of networks with a large number of nodes and vertexes with well-defined geometry and surface adhesion, and represents a first step toward very large scale integration of nanotube-vesicle networks in, for example, nanofluidic applications.
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| 2. |
- Karlsson, Mattias, 1980, et al.
(författare)
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Biomimetic nanoscale reactors and networks
- 2004
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Ingår i: Annual Review of Physical Chemistry. - : Annual Reviews. - 0066-426X .- 1545-1593. ; 55, s. 613-49
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Tidskriftsartikel (refereegranskat)abstract
- Methods based on self-assembly, self-organization, and forced shape transformations to form synthetic or semisynthetic enclosed lipid bilayer structures with several properties similar to biological nanocompartments are reviewed. The procedures offer unconventional micro- and nanofabrication routes to yield complex soft-matter devices for a variety of applications for example, in physical chemistry and nanotechnology. In particular, we describe novel micromanipulation methods for producing fluid-state lipid bilayer networks of nanotubes and surface-immobilized vesicles with controlled geometry, topology, membrane composition, and interior contents. Mass transport in nanotubes and materials exchange, for example, between conjugated containers, can be controlled by creating a surface tension gradient that gives rise to a moving boundary or by induced shape transformations. The network devices can operate with extremely small volume elements and low mass, to the limit of single molecules and particles at a length scale where a continuum mechanics approximation may break down. Thus, we also describe some concepts of anomalous fluctuation-dominated kinetics and anomalous diffusive behaviours, including hindered transport, as they might become important in studying chemistry and transport phenomena in these confined systems. The networks are suitable for initiating and controlling chemical reactions in confined biomimetic compartments for rationalizing, for example, enzyme behaviors, as well as for applications in nanofluidics, bioanalytical devices, and to construct computational and complex sensor systems with operations building on chemical kinetics, coupled reactions and controlled mass transport.
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| 3. |
- Hurtig, Johan, 1974, et al.
(författare)
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Electrophoretic transport in surfactant nanotube networks wired on microfabricated substrates
- 2006
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 78:15, s. 5281-5288
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Tidskriftsartikel (refereegranskat)abstract
- Nanofluidic devices are rapidly emerging as tools uniquely suited to transport and interrogate single molecules. We present a simple method to rapidly obtain compact surfactant nanotube networks of controlled geometry and length. The nanotubes, 100- 300 nm in diameter, are pulled from lipid vesicles using a micropipet technique, with multilamellar vesicles serving as reservoirs of surfactant material. In a second step, the nanotubes are wired around microfabricated SU-8 pillars. In contrast to unrestrained surfactant networks that minimize their surface free energy by minimizing nanotube path length, the technique presented here can produce nanotube networks of arbitrary geometries. For example, nanotubes can be mounted directly on support pillars, and long stretches of nanotubes can be arranged in zigzag patterns with turn angles of 180 degrees. The system is demonstrated to support electrophoretic transport of colloidal particles contained in the nanotubes down to the limit of single particles. We show that electrophoretic migration velocity is linearly dependent on the applied field strength and that a local narrowing of the nanotube diameter results from adhesion and bending around SU-8 pillars. The method presented here can aid in the fabrication of fully integrated and multiplexed nanofluidic devices that can operate with single molecules.
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| 4. |
- Hurtig, Johan, 1974, et al.
(författare)
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Injection and Transport of Bacteria in Nanotube-Vesicle Network
- 2008
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 4:7, s. 1515-1520
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Tidskriftsartikel (refereegranskat)abstract
- Microinjection of bacteria (the MG1655 strain of E. coli.) into unilamellar lipid vesicles contained in surface-immobilized nanotube-vesicle networks is demonstrated. Injected baceria can not escape from one vesicle to another as the size of interconnecting nanotubes is too small (~200 nm in diameter) to allow for entry. Bacteria can, however, be moved from one vesicle to another by using Marangoni flows. Thus, single or several species can be transferred to a neighboring vesicle at will. The technique offers new possibilities for live matter functionalization into synthetic host networks, and may provide a means of studying the effect of compartmentalization and chemical species on a single bacterium. Thus, it may serve as an experimental platform to study how vesicle-encapsulated bacteria evade destruction in macrophages or how bacteria surf along thin membrane nanotubes toward connected macrophage cell bodies
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| 5. |
- Hurtig, Johan, 1974
(författare)
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Nanotube Vesicle Networks: Immobilization and Transport Studies
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Surfactant lipids are an essential element of living cells. They are the basis for the biomembranes that envelope and divide cells into compartments. In addition to this static function, lipid membranes also play a role in dynamic processes such as transport and signaling. The development of biomimetic lipid nanotube vesicle networks and the techniques involved has been an ongoing process for over 10 years. The techniques have expanded and our abilities to observe, handle, and predict nanotube vesicle network processes have increased. The applications of these systems range from the basic research of biological membrane behavior and cellular processes to the development of pharmaceutical drugs in a user friendly medical industry environment.This thesis explores and expands techniques and applications of lipid nanotube vesicle mainly with a focus on immobilization and transport. Networks of nanotubes and vesicles offer a platform for construction of biomimetic nanofluidic devices operating down to single molecule and particle level. Highly organized and well defined lipid vesicle networks can be constructed with control over connectivity, container size, content, tube lengths and angle between nanotubes. Transport of fluid and particles confined in the network nodes can be controlled with several methods as well as modifications of content by controlled injections or chemical reaction dynamics.Among these are the pipette writing principle described in paper I, allowing fast and efficient formation and immobilization of well defined networks with regard to size, geometry and connectivity. The method developed in paper II aid in the fabrication of fully integrated and multiplexed nanofluidic devices and expands the vesicle network connectivity to the third dimension. In paper III the use of electrophoretic transport show linear velocities of transported latex beads. Moreover it is proven that nanotubes adhered to a specific epoxy surface does not collapse and can sustain transport. Nanotubes wired to microfabricated substrates are shown to introduce new functionalities to vesicle networks. Based on the experimental observations and theoretical modeling in paper IV, we conclude that Y junctions observed in nanotube-vesicle networks forms by a zipper-like mechanism. Surfactants from two branches flow through the junction and form the extension of the third nanotube branch. The incorporation of an entirely biological component into the nanotube vesicle network in paper V not only shows proof of concept but also introduces new functionality to the system. The motile bacteria E. coli can be electroinjected into unilamellar lipid vesicles retaining both viability and motility. It is also suggested that they can be utilized to alter the chemical environment.
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| 6. |
- Hurtig, Johan, 1974
(författare)
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Patterning and Controlled Adhesion of Cells and Lipid Nanotube Vesicle Networks by Microfabricated Substrates
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Networks of nanotubes and vesicles offer a platform for construction of nanofluidic devicesoperating on single molecule and particle level. Here one has the opportunity to study chemistryin confined biomimetic compartments in an environment as close to nature as possible withoutgoing in-vivo.The development of lipid vesicle networks and the techniques involved has been an ongoingprocess for over 10 years. Over the years weve expanded our abilities to observe, handle, andpredict nanotube vesicle networks. Understanding of the physical properties of these systems isimperative to the explanation of the observed behavior in the conducted experiments. But werequickly approaching the limit where we also require knowledge of how these systems act andreact to their environment. If we want to use these systems for anything more than just as cooltoy we need to get a grip on the hard physical aspects of how we choose to interact with thesesystems.The research in highly organized lipid vesicle networks is going into a regime where control ofsurface properties becomes a fundamental interest. Without proper attention to the substrate wewill never achieve our scientific goals, the use of these systems in a user friendly, research ormedical industry environment, where they can be used in the research of biological membranebehavior and cellular processes for the development of medical drugs.The scientific field of lipid nanotube vesicle networks has taken several major steps toward atechnique that is of use for the general scientific community. Among these are the cell patterningcovered in paper I, concerning electroporation of cells, the pipette writing principle described inpaper II, and in paper III, the expansion of vesicle networks to the third dimension.
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| 7. |
- Hurtig, Johan, 1974, et al.
(författare)
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Topographic SU 8 Substrates for Immobilization of Three-Dimensional Nanotube-Vesicle Networks
- 2004
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 20:13, s. 5637-5641
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Tidskriftsartikel (refereegranskat)abstract
- A method to create three-dimensional compact liposome networks, adhered to topographic substrates fabricated in the epoxy polymer SU-8 was described. The polymeric photoresist SU-8 is a highly suitable material for soybean lipid vesicle immobilization displaying sufficient contact potential for secure anchoring of liposomes and minimal lipid spreading. The material allows fluid-state lipid membrane structures to retain their structural integrity for long time periods. The use of the construction techniques increases the compactness of lipid nanotube networks as the tube density from a single vesicle is increased when access to the off-equatorial area is provided.
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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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