| 1. |
- Ahemaiti, Aikeremu, 1984, et al.
(författare)
-
A multifunctional pipette for localized drug administration to brain slices
- 2013
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Ingår i: Journal of Neuroscience Methods. - : Elsevier BV. - 0165-0270 .- 1872-678X. ; 219:2, s. 292-296
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a superfusion method utilizing an open-volume microfluidic device for administration of pharmacologically active substances to selected areas in brain slices with high spatio-temporal resolution. The method consists of a hydrodynamically confined flow of the active chemical compound, which locally stimulates neurons in brain slices, applied in conjunction with electrophysiological recording techniques to analyze the response. The microfluidic device, which is a novel free-standing multifunctional pipette, allows diverse superfusion experiments, such as testing the effects of different concentrations of drugs or drug candidates on neurons in different cell layers with high positional accuracy, affecting only a small number of cells. We demonstrate herein the use of the method with electrophysiological recordings of pyramidal cells in hippocampal and prefrontal cortex brain slices from rats, determine the dependence of electric responses on the distance of the superfusion device from the recording site, document a multifold gain in solution exchange time as compared to whole slice perfusion, and show that the device is able to store and deliver up to four solutions in a series. Localized solution delivery by means of open-volume microfluidic technology also reduces reagent consumption and tissue culture expenses significantly, while allowing more data to be collected from a single tissue slice, thus reducing the number of laboratory animals to be sacrificed for a study. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Ahemaiti, Aikeremu, 1984, et al.
(författare)
-
Spatial characterization of a multifunctional pipette for drug delivery in hippocampal brain slices
- 2015
-
Ingår i: Journal of Neuroscience Methods. - : Elsevier BV. - 0165-0270 .- 1872-678X. ; 241, s. 132-136
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Among the various fluidic control technologies, microfluidic devices are becoming powerful tools for pharmacological studies using brain slices, since these devices overcome traditional limitations of conventional submerged slice chambers, leading to better spatiotemporal control over delivery of drugs to specific regions in the slices. However, microfluidic devices are not yet fully optimized for such studies. New method: We have recently developed a multifunctional pipette (MFP), a free standing hydrodynamically confined microfluidic device, which provides improved spatiotemporal control over drug delivery to biological tissues. Results: We demonstrate herein the ability of the MFP to selectively perfuse one dendritic layer in the CA1 region of hippocampus with CNQX, an AMPA receptor antagonist, while not affecting the other layers in this region. Our experiments also illustrate the essential role of hydrodynamic confinement in sharpening the spatial selectivity in brain slice experiments. Concentration-response measurements revealed that the ability of the MFP to control local drug concentration is comparable with that of whole slice perfusion, while in comparison the required amounts of active compounds can be reduced by several orders of magnitude. Comparison with existing method: The multifunctional pipette is applied with an angle, which, compared to other hydrodynamically confined microfluidic devices, provides more accessible space for other probing and imaging techniques. Conclusions: Using the MFP it will be possible to study selected regions of brain slices, integrated with various imaging and probing techniques, without affecting the other parts of the slices.
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| 4. |
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| 5. |
- Ahrentorp, Fredrik, et al.
(författare)
-
Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils
- 2017
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 427, s. 14-18
-
Tidskriftsartikel (refereegranskat)abstract
- We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 mu m. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 mu L) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.
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| 6. |
- Ainla, Alar, 1982, et al.
(författare)
-
A Microfluidic Diluter Based on Pulse Width Flow Modulation
- 2009
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 81:13, s. 5549-5556
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that pulse width flow modulation (PWFM) can be used to design fasts accurate, and precise multi-stage dilution modules for microfluidic devices. The PWFM stage unit presented here yields 10-fold dilution, but several PWFM stages can be connected in series to yield higher-order dilutions. We have combined two stages in a device thus capable of diluting up to 100-fold, and we have experimentally determined a set of rules that can be conveniently utilized to design multistage diluters. Microfabrication with resist-based molds yielded geometrical channel height variances of 7% (22.9(16) mu m) with corresponding hydraulic resistance variances of similar to 20%. Pulsing frequencies, channel lengths, and flow pressures can be chosen within a wide range to establish the desired diluter properties. Finally, we illustrate the benefits of on-chip dilution in an example application where we investigate the effect of the Ca2+ concentration on a phospholipid bilayer spreading from a membrane reservoir onto a SiO2 surface. This is one of many possible applications where flexible concentration control is desirable.
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| 7. |
- Ainla, Alar, 1982, et al.
(författare)
-
A Microfluidic Pipette for Single-Cell Pharmacology
- 2010
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 82:11, s. 4529-4536
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a free-standing microfluidic pipette made in poly(dimethylsiloxane) having a circulating liquid tip that generates a self-con-fining volume in front of the outlet channels. The method is flexible and scalable as the geometry and the size of the recirculation zone is defined by pressure, channel number, and geometry. The pipette is capable of carrying out a variety of complex fluid processing operations, such as mixing, multiplexing, or gradient generation at selected cells in cell and tissue cultures. Using an uptake assay, we show that it is possible to generate dose response curves in situ from adherent Chinese hamster ovary cells expressing proton-activated human transient receptor potential vanilloid (hTRPV1) receptors. Using confined superfusion and cell stimulation, we could activate hTRPV1 receptors in single cells, measure the response by a patch-clamp pipette, and induce membrane bleb formation by exposing selected groups of cells to formaldehyde/dithiothreitol-containing solutions, respectively. In short, the microfluidic pipette allows for complex, contamination-free multiple-compound delivery for pharmacological screening of intact adherent cells.
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| 8. |
- Ainla, Alar, 1982, et al.
(författare)
-
A multi-purpose microfluidic pipette for single-cell analysis
- 2010
-
Ingår i: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2010, MicroTAS 2010; Groningen; Netherlands; 3 October 2010 through 7 October 2010. - 9781618390622 ; 2, s. 932-934
-
Konferensbidrag (refereegranskat)abstract
- We report a multi-purpose microfluidic pipette, with a recirculating liquid tip. This device, made in poly(dimethylsiloxane), enables contamination-free manipulation and chemical stimulation of selected single cells in cell collectives or tissue slices. The pipette is capable of carrying out a variety of complex fluid processing functionalities, such as mixing, multiplexing, or gradient generation. The concept is flexible and scalable as the geometry and the size of the recirculation zone is defined by pressure, channel number, and geometry. We have applied the pipette in a fluorescence uptake assay, electrophysiology studies and for chemical induction of membrane protrusion from biological cells.
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| 9. |
- Ainla, Alar, 1982, et al.
(författare)
-
A multifunctional pipette
- 2012
-
Ingår i: Lab on a Chip - Miniaturisation for Chemistry and Biology. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 12:7, s. 1255-1261
-
Tidskriftsartikel (refereegranskat)abstract
- Microfluidics has emerged as a powerful laboratory toolbox for biologists, allowing manipulation and analysis of processes at a cellular and sub-cellular level, through utilization of microfabricated features at size-scales relevant to that of a single cell. In the majority of microfluidic devices, sample processing and analysis occur within closed microchannels, imposing restrictions on sample preparation and use. We present an optimized non-contact open-volume microfluidic tool to overcome these and other restrictions, through the use of a hydrodynamically confined microflow pipette, serving as a multifunctional solution handling and dispensing tool. The geometries of the tool have been optimised for use in optical microscopy, with integrated solution reservoirs to reduce reagent use, contamination risks and cleaning requirements. Device performance was characterised using both epifluorescence and total internal reflection fluorescence (TIRF) microscopy, resulting in similar to 200 ms and similar to 130 ms exchange times at similar to 100 nm and similar to 30 mm distances to the surface respectively.
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| 10. |
- Ainla, Alar, 1982, et al.
(författare)
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Hydrodynamic Flow Confinement Technology in Microfluidic Perfusion Devices
- 2012
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 3:2, s. 442-461
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Forskningsöversikt (refereegranskat)abstract
- Hydrodynamically confined flow device technology is a young research area with high practical application potential in surface processing, assay development, and in various areas of single cell research. Several variants have been developed, and most recently, theoretical and conceptual studies, as well as fully developed automated systems, were presented. In this article we review concepts, fabrication strategies, and application areas of hydrodynamically confined flow (HCF) devices.
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| 11. |
- Ainla, Alar, 1982, et al.
(författare)
-
Lab on a Biomembrane
- 2014
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Ingår i: Biophysical Journal. - 0006-3495 .- 1542-0086. ; 106:2, s. 209A-209A
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 12. |
- Ainla, Alar, 1982, et al.
(författare)
-
Lab on a Biomembrane: Rapid prototyping and manipulation of 2D fluidic lipid bilayers circuits
- 2013
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- Lipid bilayer membranes are among the most ubiquitous structures in the living world, with intricate structural features and a multitude of biological functions. It is attractive to recreate these structures in the laboratory, as this allows mimicking and studying the properties of biomembranes and their constituents, and to specifically exploit the intrinsic two-dimensional fluidity. Even though diverse strategies for membrane fabrication have been reported, the development of related applications and technologies has been hindered by the unavailability of both versatile and simple methods. Here we report a rapid prototyping technology for two-dimensional fluidic devices, based on in-situ generated circuits of phospholipid films. In this "lab on a molecularly thin membrane'', various chemical and physical operations, such as writing, erasing, functionalization, and molecular transport, can be applied to user-defined regions of a membrane circuit. This concept is an enabling technology for research on molecular membranes and their technological use.
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| 13. |
- Ainla, Alar, 1982, et al.
(författare)
-
Single-cell electroporation using a multifunctional pipette
- 2012
-
Ingår i: Lab on a Chip - Miniaturisation for Chemistry and Biology. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 12:22, s. 4605-4609
-
Tidskriftsartikel (refereegranskat)abstract
- We present here a novel platform combination, using a multifunctional pipette to individually electroporate single-cells and to locally deliver an analyte, while in their culture environment. We demonstrate a method to fabricate low-resistance metallic electrodes into a PDMS pipette, followed by characterization of its effectiveness, benefits and limits in comparison with an external carbon microelectrode.
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| 14. |
- Ali Doosti, Baharan, 1991, et al.
(författare)
-
Generation of interconnected vesicles in a liposomal cell model
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce an experimental method based upon a glass micropipette microinjection technique for generating a multitude of interconnected vesicles (IVs) in the interior of a single giant unilamellar phospholipid vesicle (GUV) serving as a cell model system. The GUV membrane, consisting of a mixture of soybean polar lipid extract and anionic phosphatidylserine, is adhered to a multilamellar lipid vesicle that functions as a lipid reservoir. Continuous IV formation was achieved by bringing a micropipette in direct contact with the outer GUV surface and subjecting it to a localized stream of a Ca2+ solution from the micropipette tip. IVs are rapidly and sequentially generated and inserted into the GUV interior and encapsulate portions of the micropipette fluid content. The IVs remain connected to the GUV membrane and are interlinked by short lipid nanotubes and resemble beads on a string. The vesicle chain-growth from the GUV membrane is maintained for as long as there is the supply of membrane material and Ca2+ solution, and the size of the individual IVs is controlled by the diameter of the micropipette tip. We also demonstrate that the IVs can be co-loaded with high concentrations of neurotransmitter and protein molecules and displaying a steep calcium ion concentration gradient across the membrane. These characteristics are analogous to native secretory vesicles and could, therefore, serve as a model system for studying secretory mechanisms in biological systems.
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| 15. |
- Athanasiou, Vasileios, 1988, et al.
(författare)
-
On Sensing Principles Using Temporally Extended Bar Codes
- 2020
-
Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 20:13, s. 6782-6791
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of ionic variation patterns could be a significant marker for the diagnosis of neurological and other diseases. This paper introduces a novel idea for training chemical sensors to recognise patterns of ionic variations. By using an external voltage signal, a sensor can be trained to output distinct time-series signals depending on the state of the ionic solution. Those sequences can be analysed by a relatively simple readout layer for diagnostic purposes. The idea is demonstrated on a chemical sensor that is sensitive to zinc ions with a simple goal of classifying zinc ionic variations as either stable or varying. The study features both theoretical and experimental results. By extensive numerical simulations, it has been shown that the proposed method works successfully in silico. Distinct time-series signals are found which occur with a high probability under only one class of ionic variations. The related experimental results point in the right direction.
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| 16. |
- Balasubramaniam, S., et al.
(författare)
-
A review of experimental opportunities for molecular communication
- 2013
-
Ingår i: Nano Communication Networks. - : Elsevier BV. - 1878-7789. ; 4:2, s. 43-52
-
Tidskriftsartikel (refereegranskat)abstract
- The growth of nanotechnology has led to miniature devices that are able to perform limited functionalities in hard to access areas. Example nanodevice applications in the healthcare domain include early detection of harmful diseases. The current field of molecular communication is aiming to increase the functionalities of nanodevices, by enabling communication to be performed. Since its first introduction, communication researchers have been proposing various solutions that could possibly realize molecular communications (e.g., molecular diffusion and bacteria nanonetworks). These solutions have largely been limited to theoretical simulation modeling. However, to fully realize a future for real deployments and developments of molecular communication, a strong synergy will be required with molecular biologists. The aim of this paper is to create this link, and at the same time provide guidance for current molecular communication researchers of possible real developments of molecular communication based on the current state-of-the-art experimental work. In particular, we present a review on bacteria communication and membrane nanotubes, as well as neuronal networks. We also discuss possible applications in the future focusing in particular on Body Area NanoNetworks (BAN2). © 2013 Elsevier Ltd.
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| 17. |
- Benkoski, Jason J., 1975, et al.
(författare)
-
Light-Regulated release of liposomes from phospholipid membranes via photoresponsive polymer-DNA conjugates
- 2006
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 2:8, s. 710-715
-
Tidskriftsartikel (refereegranskat)abstract
- A method for releasing tethered liposomes from a supported lipid bilayer in response to a light stimulus is described. The tethering is accomplished through the hybridization of end-functionalized DNA that resides on both the supported lipid bilayer and liposome surfaces. Normally consisting of cholesterol or lipid tails, the end group is replaced in this study by a photoresponsive polymer that partitions into lipid bilayers at physiological pH. When exposed to UV light, it undergoes excited state proton transfer with water. The ensuing increase in polarity increases the solubility of the polymer in the aqueous phase. Quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence microscopy have been used to record both the construction of the vesicle assembly and the subsequent response to UV light. It is found that the critical flow rate for vesicle release is reduced when buffer flow is performed in conjunction with UV exposure. © The Royal Society of Chemistry 2006.
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| 18. |
- Billerit, Celine, 1977, et al.
(författare)
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Formation of giant unilamellar vesicles from spin-coated lipid films by localized IR heating
- 2012
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 8:42, s. 10823-10826
-
Tidskriftsartikel (refereegranskat)abstract
- We report a novel method for the generation of GUVs (generate unilamellar vesicles) from spin-coated lipid films by means of localized heating. This technique enables GUV formation from both charged and neutral lipid species, as well as from a complex lipid mixture, in various ionic strength conditions. Encapsulation was possible during and after GUV formation.
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| 19. |
- Billerit, Celine, 1977, et al.
(författare)
-
Heat-induced formation of single giant unilamellar vesicles
- 2011
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 7:20, s. 9751-9757
-
Tidskriftsartikel (refereegranskat)abstract
- Giant unilamellar vesicles (GUVs) are an excellent model system for the investigation of lipid membranes, the study of membrane proteins and ion channels in a biomimetic environment, and in the creation of artificial cells. Here, we describe a novel method for the preparation of GUVs from single multilamellar liposomes by means of directed infrared laser heating. Our method generates individual unilamellar vesicles at selected locations, not only from natural and artificial lipid mixtures containing negatively charged lipids, but also from preparations of single lipids, such as neutral phosphatidylethanolamine. The presented method provides a new efficient resource for giant vesicle research and offers an alternative to the electroformation and de/rehydration techniques.
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| 20. |
- Bridle, Helen, 1979, et al.
(författare)
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On-chip fabrication to add temperature control to a microfluidic solution exchange system
- 2008
-
Ingår i: Lab on a Chip - Miniaturisation for Chemistry and Biology. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 8:3, s. 480-483
-
Tidskriftsartikel (refereegranskat)abstract
- We present a concept for the post production modification of commercially available microfluidic devices to incorporate local temperature control, thus allowing for the exact alignment of heating structures with the existing features, e.g. wells, channels or valves, of a system. Specifically, we demonstrate the application of programmable local heating, controlled by computerized PI regulation, to a rapid solution exchanger. Characterisation of the system to show that both uniform temperature distributions and temperature gradients can be established, and to confirm that the solution exchange properties are undisturbed by heating, was achieved using in situ thermometry and amperometry. © The Royal Society of Chemistry.
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| 21. |
- Chang, S, et al.
(författare)
-
An electrowetting-based microfluidic platform for magnetic bioassays
- 2010
-
Ingår i: The 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2010, 3-7 Oktober, Groningen, Neterlands. - 9781618390622 ; 2, s. 1331-1333
-
Konferensbidrag (refereegranskat)abstract
- Here we present our recent work on a droplet-based microfluidic device for manipulating microliter-sized droplets. By replacing the formerly used common dielectric SiO2 with Si3N4 and applying a 33 nm thick Teflon top layer to create a hydrophobic surface, we successfully lowered the actuation voltage from 450 V to 50 Vdc/40 Vac. Sputtered HfO2 with high dielectric constant was also investigated as an insulator, which could reproducibly yield thin defect-free insulation layers and lower the actuation voltage to less than 40 V.
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| 22. |
- Czolkos, Ilja, 1980, et al.
(författare)
-
Controlled formation and mixing of two-dimensional fluids
- 2007
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:7, s. 1980-1984
-
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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| 23. |
- Czolkos, Ilja, 1980, et al.
(författare)
-
Flow control of thermotropic lipid monolayers
- 2011
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 7:15, s. 6926-6933
-
Tidskriftsartikel (refereegranskat)abstract
- There is an increasing interest in using liquid crystalline media as mobile phases in two-dimensional nanofluidic systems. Their small-scale, reduced dimensionality, and plentiful opportunities for functionalisation render such phases advantageous. However, flow control has been difficult to achieve, as the wetting processes which drive area expansion are not dynamically controllable. Here, we report on temperature-controlled monolayer spreading of 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) on the hydrophobic substrates SU-8, and Teflon AF (amorphous fluoropolymer). The gel/liquid phase transition of DEPE at T(c) similar to 38 degrees C is exploited to toggle spreading of a molecular lipid film on SU-8. We observed that on Teflon AF, DEPE monolayer spreading occurs even below T(c), and exhibits strongly accelerated spreading above the phase transition temperature. Our results demonstrate that switching DEPE monolayer spreading on and off, or, alternatively, switching between fast and slow area expansion, is a feasible approach towards establishing control over lipid film flow in two-dimensional fluidic systems. We also present a chip-based device integrating a patterned surface for 2D-microfluidics and on-chip heating.
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| 24. |
- Czolkos, Ilja, 1980, et al.
(författare)
-
High-Resolution Micropatterned Teflon AF Substrates for Biocompatible Nanofluidic Devices
- 2012
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 28:6, s. 3200-3205
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a general photolithography-based process for the microfabrication of surface-supported Teflon AF structures. Teflon AF patterns primarily benefit from superior optical properties such as very low autofluorescence and a low refractive index. The process ensures that the Teflon AF patterns remain strongly hydrophobic in order to allow rapid lipid monolayer spreading and generates a characteristic edge morphology which assists directed cell growth along the structured surfaces. We provide application examples, demonstrating the well-controlled mixing of lipid films on Teflon AF structures and showing how the patterned surfaces can be used as biocompatible growth-directing substrates for cell culture. Chinese hamster ovary (CHO) cells develop in a guided fashion along the sides of the microstructures, selectively avoiding to grow over the patterned areas.
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| 25. |
- Czolkos, Ilja, 1980, et al.
(författare)
-
Molecular phospholipid films on solid supports
- 2011
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 7:10, s. 4562-4576
-
Tidskriftsartikel (refereegranskat)abstract
- Phospholipid membranes are versatile structures for mimicking biological surfaces. Bilayer and monolayer membranes can be formed on solid supports, leading to enhanced stability and accessibility of the biomimetic molecular film. This has facilitated functional studies of membrane proteins and aided the development of membrane-based applications in, for example, biosensing, self-assembled reaction kinetics and catalysis. Assembly and preparation of lipid films on supporting surfaces is a challenging engineering task with the goal of fabricating mechanically, chemically and thermodynamically stable lipid membranes. In this review, the current state of the art of molecularly thin lipid layer fabrication is presented with an emphasis on support materials, film formation mechanisms, characterisation methods, and applications.
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| 26. |
- Czolkos, Ilja, 1980, et al.
(författare)
-
Platform for Controlled Supramolecular Nano-Assembly
- 2009
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:6, s. 2482-2486
-
Tidskriftsartikel (refereegranskat)abstract
- We here present a two-dimensional (2D) micro/nano-fluidic technique where reactant-doped liquid−crystal films spread and mix on micro- and nanopatterned substrates. Surface-supported phospholipid monolayers are individually doped with complementary DNA molecules which hybridize when these lipid films mix. Using lipid films to convey reactants reduces the dimensionality of traditional 3D chemistry to 2D, and possibly to 1D by confining the lipid film to nanometer-sized lanes. The hybridization event was observed by FRET using single-molecule-sensitive confocal fluorescence detection. We could successfully detect hybridization in lipid streams on 250 nm wide lanes. Our results show that the number and density of reactants as well as sequence of reactant addition can be controlled within confined liquid crystal films, providing a platform for nanochemistry with potential for kinetic control.
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| 27. |
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| 28. |
- Erkan, Yavuz, 1982, et al.
(författare)
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Direct immobilization of cholesteryl-TEG-modified oligonucleotides onto hydrophobic SU-8 surfaces
- 2007
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 23:10, s. 5259-5263
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce a rapid, simple one-step procedure for the high-yield immobilization of cholesteryl- tetraethyleneglycol-modified oligonucleotides ( chol- DNA) at hydrophobic sites made of SU-8 photoresist. Topographic structures of SU-8 were microfabricated on microscope glass coverslips sputtered with a Ti/Au layer. Upon application, chol-DNA adsorbed to the SU-8 structures from solution, leaving the surrounding gold surface free of chol- DNA. chol-DNA immobilization is complete within 15 min and yields a surface coverage in the range of 20- 95 pmol/ cm(2), which corresponds to a film density of 10(12)- 10(13) molecules/cm(2). chol-DNA immobilization is stable and can be sustained despite rinsing, drying, dry storage for several hours, and rehydration of chips. Furthermore, complementary DNA in solution hybridizes efficiently to immobilized chol-DNA. We introduce a rapid, simple one-step procedure for the high-yield immobilization of cholesteryl-tetraethyleneglycol-modified oligonucleotides (chol-DNA) at hydrophobic sites made of SU-8 photoresist. Topographic structures of SU-8 were microfabricated on microscope glass coverslips sputtered with a Ti/Au layer. Upon application, chol-DNA adsorbed to the SU-8 structures from solution, leaving the surrounding gold surface free of chol-DNA. chol-DNA immobilization is complete within 15 min and yields a surface coverage in the range of 20-95 pmol/cm(2), which corresponds to a film density of 10(12)-10(13) molecules/cm(2). chol-DNA immobilization is stable and can be sustained despite rinsing, drying, dry storage for several hours, and rehydration of chips. Furthermore, complementary DNA in solution hybridizes efficiently to immobilized chol-DNA.
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| 29. |
- Gözen, Irep, 1980, et al.
(författare)
-
Autonomous Development of Compositional Diversity in Self-Spreading Flat Protocells
- 2024
-
Ingår i: ChemSystemsChem. - 2570-4206. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental pathway to the spontaneous generation of compositionally diverse synthetic protocells is presented. The pathway is initiated by flat giant unilamellar vesicles (FGUVs) that originate from compositionally different multilamellar lipid reservoirs and undergo spontaneous spreading across solid surfaces. On contact, the spreading FGUVs merge to produce a concentration gradient in membrane lipids across the fusion interface. Subsequent reconstruction through a series of shape transformations produces a network of nanotube-connected lipid vesicles that inherit different ratios of the membrane constituents derived from the bilayers of the parent FGUVs. The fusion process leads to the engulfment of small FGUVs by larger FGUVs, mimicking predator-prey behavior in which the observable characteristics of the prey are lost but the constituents are carried by the predator FGUV to the next generation of lipid vesicles. We speculate that our results could provide a feasible pathway to autonomous protocell diversification in origin of life theories and highlight the possible role of solid surfaces in the development of diversity and rudimentary speciation of natural protocells on the early Earth.
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| 30. |
- Gözen, Irep, 1980, et al.
(författare)
-
Calcium-ion-controlled nanoparticle-induced tubulation in supported flat phospholipid vesicles
- 2011
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 7:20, s. 9706-9713
-
Tidskriftsartikel (refereegranskat)abstract
- Biological nanotubes, often referred to as tunneling nanotubes, fulfill important functions within the cell, e.g. by supplying cell components, conducting signals and transporting virus particles and bacteria. Many functions are still insufficiently understood, which has placed these nanostructures in the focus of recent investigation. We report here on our observations of transient tubulation in nanoparticle-containing, supported flat giant unilamellar vesicles (FGUVs). The encapsulation of nanoparticles in FGUVs in conjunction with low (1-4 mM) Ca(2+) in the ambient buffer solution resulted in transient tube formation. Tubes extended from the FGUV up to a length of several hundred micrometres and exhibited, on some occasions, vesicle encapsulation. The findings represent an interesting confirmation of several reported theoretical and practical models of tube formation in biological or biomimetic systems.
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| 31. |
- Gözen, Irep, 1980, et al.
(författare)
-
Evidence for membrane flow through pores in stacked phospholipid membranes
- 2012
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 8:23, s. 6220-6225
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Tidskriftsartikel (refereegranskat)abstract
- We present evidence for an inter-bilayer transport mode of lipid molecules in solid-supported double bilayer membranes via membrane defects. The observation of avalanche rupturing in isolated membrane areas of flat giant unilamellar vesicles, i.e., double bilayers, in the distal (with respect to the solid support) bilayer revealed migration of the membrane material between the stacked bilayers, which we can explain by the presence of defects. The presence of the interconnections was indirectly observed by monitoring the area development of the isolated membrane patches during rupturing. These new findings can help to better describe the dynamic processes in biological structures, featuring stacks of phospholipid bilayers, such as mitochondrial shape dynamics.
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| 32. |
- Gözen, Irep, 1980, et al.
(författare)
-
Fractal avalanche ruptures in biological membranes
- 2010
-
Ingår i: Nature Materials. - 1476-4660 .- 1476-1122. ; 9:11, s. 908-912
-
Tidskriftsartikel (refereegranskat)abstract
- Bilayer membranes envelope cells as well as organelles, and constitute the most ubiquitous biological material found in all branches of the phylogenetic tree. Cell membrane rupture is an important biological process, and substantial rupture rates are found in skeletal and cardiac muscle cells under a mechanical load(1). Rupture can also be induced by processes such as cell death(2), and active cell membrane repair mechanisms are essential to preserve cell integrity(3). Pore formation in cell membranes is also at the heart of many biomedical applications such as in drug, gene and short interfering RNA delivery(4). Membrane rupture dynamics has been studied in bilayer vesicles under tensile stress(5-8), which consistently produce circular pores(5,6). We observed very different rupture mechanics in bilayer membranes spreading on solid supports: in one instance fingering instabilities were seen resulting in floral-like pores and in another, the rupture proceeded in a series of rapid avalanches causing fractal membrane fragmentation. The intermittent character of rupture evolution and the broad distribution in avalanche sizes is consistent with crackling-noise dynamics(9). Such noisy dynamics appear in fracture of solid disordered materials(10), in dislocation avalanches in plastic deformations(11) and domain wall magnetization avalanches(12). We also observed similar fractal rupture mechanics in spreading cell membranes.
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| 33. |
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| 34. |
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| 35. |
- Gözen, Irep, 1980, et al.
(författare)
-
Protocells: Milestones and Recent Advances
- 2022
-
Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 18:18
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Forskningsöversikt (refereegranskat)abstract
- The origin of life is still one of humankind's great mysteries. At the transition between nonliving and living matter, protocells, initially featureless aggregates of abiotic matter, gain the structure and functions necessary to fulfill the criteria of life. Research addressing protocells as a central element in this transition is diverse and increasingly interdisciplinary. The authors review current protocell concepts and research directions, address milestones, challenges and existing hypotheses in the context of conditions on the early Earth, and provide a concise overview of current protocell research methods.
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| 36. |
- Gözen, Irep, 1980, et al.
(författare)
-
Repair of large area pores in supported double bilayers
- 2013
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 9:10, s. 2787-2792
-
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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| 37. |
- Gözen, Irep, 1980, et al.
(författare)
-
Thermal migration of molecular lipid films as a contactless fabrication strategy for lipid nanotube networks
- 2013
-
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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| 38. |
- Hannestad, Jonas, 1981, et al.
(författare)
-
Kinetics of Diffusion-Mediated DNA Hybridization in Lipid Monolayer Films Determined by Single-Molecule Fluorescence Spectroscopy
- 2013
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 7:1, s. 308-315
-
Tidskriftsartikel (refereegranskat)abstract
- We use single-molecule fluorescence microscopy to monitor individual hybridization reactions between membrane-anchored DNA strands, occurring in nanofluidic lipid monolayer films deposited on Teflon AF substrates. The DNA molecules are labeled with different fluorescent dyes, which make it possible to simultaneously monitor the movements of two different molecular species, thus enabling tracking of both reactants and products. We employ lattice diffusion simulations to determine reaction probabilities upon interaction. The observed hybridization rate of the 40-mer DNA was more than 2-fold higher than that of the 20-mer DNA. Since the lateral diffusion coefficient of the two different constructs is nearly identical, the effective molecule radius determines the overall kinetics. This implies that when two DNA molecules approach each other, hydrogen bonding takes place distal from the place where the DNA is anchored to the surface. Strand closure then propagates bidirectionally through a zipper-like mechanism, eventually bringing the lipid anchors together. Comparison with hybridization rates for corresponding DNA sequences in solution reveals that hybridization rates are lower for the lipid-anchored strands and that the dependence on strand length is stronger.
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| 39. |
- Jansson, Erik, 1984, et al.
(författare)
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Microfluidic Flow Cell for Sequential Digestion of Immobilized Proteoliposomes
- 2012
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 84:13, s. 5582-5588
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed a microfluidic flow cell where stepwise enzymatic digestion is performed on immobilized proteoliposomes and the resulting cleaved peptides are analyzed with liquid chromatography–tandem mass spectrometry (LC–MS/MS). The flow cell channels consist of two parallel gold surfaces mounted face to face with a thin spacer and feature an inlet and an outlet port. Proteoliposomes (50–150 nm in diameter) obtained from red blood cells (RBC), or Chinese hamster ovary (CHO) cells, were immobilized on the inside of the flow cell channel, thus forming a stationary phase of proteoliposomes. The rate of proteoliposome immobilization was determined using a quartz crystal microbalance with dissipation monitoring (QCM-D) which showed that 95% of the proteoliposomes bind within 5 min. The flow cell was found to bind a maximum of 1 μg proteoliposomes/cm2, and a minimum proteoliposome concentration required for saturation of the flow cell was determined to be 500 μg/mL. Atomic force microscopy (AFM) studies showed an even distribution of immobilized proteoliposomes on the surface. The liquid encapsulated between the surfaces has a large surface-to-volume ratio, providing rapid material transfer rates between the liquid phase and the stationary phase. We characterized the hydrodynamic properties of the flow cell, and the force acting on the proteoliposomes during flow cell operation was estimated to be in the range of 0.1–1 pN, too small to cause any proteoliposome deformation or rupture. A sequential proteolytic protocol, repeatedly exposing proteoliposomes to a digestive enzyme, trypsin, was developed and compared with a single-digest protocol. The sequential protocol was found to detect 65% more unique membrane-associated protein (p
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| 40. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
COMPLEX NANOTUBE-LIPOSOME NETWORKS
- 2009
-
Ingår i: Methods in Enzymology. - 1557-7988 .- 0076-6879. ; 464:C, s. 309-325
-
Tidskriftsartikel (refereegranskat)abstract
- Surfactant nanotube-vesicle networks (NVN) belong to the smallest artificial devices known to date for performing controlled chemical operations with enzymes. Newly established means for transport of chemical reactants between containers, as well as advancements in initiation and control of chemical reactions in such systems have opened pathways to new devices with a resolution down to the single-molecule level. Here, we summarize the fabrication and functionalization of complex nanotube-liposome networks for such devices, and discuss related aspects of their application for studying chemical kinetics and materials transport phenomena in ultrasmall-scale bio-mimetic environments.
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| 41. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
Controlling Chemistry in Dynamic Nanoscale Systems
- 2010
-
Ingår i: Springer Series in Chemical Physics. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0172-6218. - 9783642025969 ; 96, s. 449-468
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The biological cell, the fundamental building block of the living world, is a complex maze of compartmentalized biochemical reactors that embed tens of thousands of chemical reactions running in parallel. Several, if not all, reactors are systematically interconnected by a web of nanofluidic transporters, such as nanotubes, vesicles, and membrane pores with ever-changing shapes and structures [1]. To initiate, terminate, or control chemical reactions, small-scale poly-/pleiomorphic systems undergo rapid and violent shape changes with energy barriers close to kBT , where, due to the small dimensions, diffusional mixing of reactants is rapid. The geometry, i.e. volume, and shape changes can be utilized to control both kinetic and thermodynamic properties of the system. This is in sharp contrast to the man-made macroscopic bioreactors, in which mixing of reactants is aided by mechanical means, such as stirring or sonication, under the assumption that reactions take place in volumes that do not change over time. Such reaction volumes are compact, like a sphere, a cube, or a cylinder, and do not provide for variation of shape. Ordinarily, reaction rates, mechanisms, and thermodynamic properties of chemical reactions in condensed media are based on these assumptions. A number of important questions and challenges arise from these facts. For example, how will we achieve fundamental understanding of how reactor shape affects chemistry on the nanoscale, how do we develop appropriate and powerful experimental model systems, and last but not least what impact will this knowledge have on the design and function of nanotechnological devices with new operation modes derived from natural principles.
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| 42. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
Controlling the internal structure of giant unilamellar vesicles by means of reversible temperature dependent sol-gel transition of internalized poly(N-isopropyl acrylamide)
- 2005
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 21:4, s. 1230-1237
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we present preparation and basic applications of lipid-bilayer-enclosed picoliter volumes (microcontainers) of solutions of poly(N-isopropylacrylamide) (PNIPAAm). Giant unilamellar vesicles (GUVs) were prepared from phospholipids using a standard swelling procedure and subsequently surface immobilized. Clear, slightly viscous solutions of PNIPAAm of varying concentration in aqueous buffer were directly pressure-microinjected into the GUVs, using a submicrometer-sized, pointed capillary. The GUV was subjected to changing temperature over a 21-40 °C range. The typical phase transition of the polymeric material upon heating and cooling across the lower critical solution temperature was followed using optical microscopy and shown to be reversible over multiple sequential heating/cooling cycles without compromising the integrity of the GUV membrane. Fluorescent, carboxylic acid modified 200 nm latex beads, co-injected with the PNIPAAm solution, were temperature-reversibly immobilized during the phase transition, practically freezing the Brownian motion of the entrapped particles in the volume. Furthermore, a co-injected water soluble fluorescent polysaccharide - dye conjugate was shown not to migrate from the aqueous phase into the hydrophobic polymer part upon heating, whereas the fluorescent beads were completely but reversibly immobilized in the hydrophobic domains of dense polymer agglomerates. The system reported here provides a feasible method for the reversible stabilization and solidification of GUV interior volumes, e.g., as a micrometer-sized model system for controlled drug release.
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| 43. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
Generation of phospholipid vesicle-nanotube networks and transport of molecules therein
- 2011
-
Ingår i: Nature Protocols. - : Springer Science and Business Media LLC. - 1754-2189 .- 1750-2799. ; 6:6, s. 791-805
-
Tidskriftsartikel (refereegranskat)abstract
- We describe micromanipulation and microinjection procedures for the fabrication of soft-matter networks consisting of lipid bilayer nanotubes and surface-immobilized vesicles. These biomimetic membrane systems feature unique structural flexibility and expandability and, unlike solid-state microfluidic and nanofluidic devices prepared by top-down fabrication, they allow network designs with dynamic control over individual containers and interconnecting conduits. The fabrication is founded on self-assembly of phospholipid molecules, followed by micromanipulation operations, such as membrane electroporation and microinjection, to effect shape transformations of the membrane and create a series of interconnected compartments. Size and geometry of the network can be chosen according to its desired function. Membrane composition is controlled mainly during the self-assembly step, whereas the interior contents of individual containers is defined through a sequence of microneedle injections. Networks cannot be fabricated with other currently available methods of giant unilamellar vesicle preparation (large unilamellar vesicle fusion or electroformation). Described in detail are also three transport modes, which are suitable for moving water-soluble or membrane-bound small molecules, polymers, DNA, proteins and nanoparticles within the networks. The fabrication protocol requires similar to 90 min, provided all necessary preparations are made in advance. The transport studies require an additional 60-120 min, depending on the transport regime.
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| 44. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
Liposomes: Technologies and Analytical Applications
- 2008
-
Ingår i: Annual Review of Analytical Chemistry. - 1936-1327 .- 1936-1335. ; 1, s. 801-832
-
Tidskriftsartikel (refereegranskat)abstract
- Liposomes are structurally and functionally some of the most versatile supramolecular assemblies in existence. Since the beginning of active research on lipid vesicles in 1965, the field has progressed enormously and applications are well established in several areas, such as drug and gene delivery. In the analytical sciences, liposomes serve a dual purpose: Either they are analytes, typically in quality-assessment procedures of liposome preparations, or they are functional components in a variety of new analytical systems. Liposome immunoassays, for example, benefit greatly from the amplification provided by encapsulated markers, and nanotube-interconnected liposome networks have emerged as ultrasmall-scale analytical devices. This review provides information about new developments in some of the most actively researched liposome-related topics
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| 45. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
Microfluidic technology for investigation of protein function in single adherent cells
- 2019
-
Ingår i: Methods in Enzymology. - : Elsevier. - 1557-7988 .- 0076-6879. ; 628
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Instrumental techniques and associated methods for single cell analysis, designed to investigate and measure a broad range of cellular parameters in search of unique features, address key limitations of conventional cell-based assays with their ensemble average response. While many different single cell techniques exist for suspension cultures, which can process and characterize large numbers of individual cells in rapid succession, the access to surface-immobilized cells in typical 2D and 3D culture environments remains challenging. Open space microfluidics has created new possibilities in this area, allowing for exclusive access to single cells in adherent cultures, even at high confluency. In this chapter, we briefly review new microtechnologies for the investigation of protein function in single adherent cells, and present an overview over related recent applications of the multifunctional pipette (Biopen), a microfluidic multi-solution dispensing system that uses hydrodynamic confinement in open volume environments in order to establish a superfusion zone over selected single cells in adherent cultures.
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| 46. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
NANOFLUIDICS Neither shaken nor stirred
- 2012
-
Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 7:1, s. 6-7
-
Tidskriftsartikel (refereegranskat)
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| 47. |
|
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| 48. |
- Jesorka, Aldo, 1967, et al.
(författare)
-
Water coordinated zinc dioxo-chlorin and porphyrin self-assemblies as chlorosomal mimics: Variability of supramolecular interactions
- 2012
-
Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 11:6, s. 1069-1080
-
Tidskriftsartikel (refereegranskat)abstract
- Semisynthetic zinc chlorins are shown for the first time to self-assemble in the absence of an intrinsic hydroxy group, which is always present in the chlorosomal bacteriochlorophylls (BChl's) c, d and e. Instead, the presently studied compounds have carbonyl groups. These cannot function as hydrogen bond donating groups. However due to interspacing water molecules bound to the zinc ion, double hydrogen bonding can occur to adjacent tetrapyrrolic macrocycles equipped with carbonyl recognition groups. Solution studies comprising UV-Vis absorption, electronic circular dichroism (ECD) and FT-IR show that different aggregates are formed in hydrated solvents in comparison to dry nonpolar solvents. Single crystal X-ray studies show variable supramolecular interactions either with interspacing water molecules coordinating the Zn ion within a porphyrin or with the 17 2 carbonyl group of a chlorin ligating the Zn ion. Our findings have implications for a minimalistic design of self-assembling chromophores, which can act as efficient light-harvesting units.
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| 49. |
- Jõemetsa, Silver, 1990, et al.
(författare)
-
Molecular Lipid Films on Microengineering Materials
- 2019
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 35:32, s. 10286-10298
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we have systematically investigated the formation of molecular phospholipid films on a variety of solid substrates fabricated from typical surface engineering materials and the fluidic properties of the lipid membranes formed on these substrates. The surface materials comprise of borosilicate glass, mica, SiO2, Al (native oxide), Al2O3, TiO2, ITO, SiC, Au, Teflon AF, SU-8, and graphene. We deposited the lipid films from small unilamellar vesicles (SUVs) by means of an open-space microfluidic device, observed the formation and development of the films by laser scanning confocal microscopy, and evaluated the mode and degree of coverage, fluidity, and integrity. In addition to previously established mechanisms of lipid membrane–surface interaction upon bulk addition of SUVs on solid supports, we observed nontrivial lipid adhesion phenomena, including reverse rolling of spreading bilayers, spontaneous nucleation and growth of multilamellar vesicles, and the formation of intact circular patches of double lipid bilayer membranes. Our findings allow for accurate prediction of membrane–surface interactions in microfabricated devices and experimental environments where model membranes are used as functional biomimetic coatings.
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| 50. |
- Kalaboukhov, Alexei, 1975, et al.
(författare)
-
Operation of a high-T-C SQUID gradiometer with a two-stage MEMS-based Joule-Thomson micro-cooler
- 2016
-
Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 29:9
-
Tidskriftsartikel (refereegranskat)abstract
- Practical applications of high-T-C superconducting quantum interference devices (SQUIDs) require cheap, simple in operation, and cryogen-free cooling. Mechanical cryo-coolers are generally not suitable for operation with SQUIDs due to their inherent magnetic and vibrational noise. In this work, we utilized a commercial Joule-Thomson microfluidic two-stage cooling system with base temperature of 75 K. We achieved successful operation of a bicrystal high-T-C SQUID gradiometer in shielded magnetic environment. The micro-cooler head contains neither moving nor magnetic parts, and thus does not affect magnetic flux noise of the SQUID even at low frequencies. Our results demonstrate that such a microfluidic cooling system is a promising technology for cooling of high-T-C SQUIDs in practical applications such as magnetic bioassays.
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