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K.s.e. Forssberg - One of the best experts on this subject based on the ideXlab platform.
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mechanism of oleate interaction on salt type minerals v adsorption and precipitation reactions in relation to the solid liquid ratio in the synthetic fluorite sodium oleate system
Journal of Colloid and Interface Science, 1991Co-Authors: J M Cases, K.s.e. ForssbergAbstract:Abstract The mechanism of adsorption of oleate onto a synthetic fluorite sample at different solid/liquid ratios in alkaline solutions is elucidated through adsorption isotherms in conjunction with ζ-potential and diffuse reflectance Fourier transform-infrared spectroscopic studies. These studies show that the chemisorption of oleate on surface calcium species followed by the physical adsorption of hydrocarbon chains (Bilayer Formation) precede the precipitation of calcium oleate in bulk solution. With an increase in the solid/liquid ratio, the bulk precipitation of calcium oleate after Bilayer Formation is found to be reduced, and at a high solid concentration, the isotherm is seen to level off with Bilayer Formation. As the solid concentration increases, the concentration of calcium in bulk solution decreases because of its adsorption on the head group of the hydrophilic layer of oleate (Bilayer), and hence the extent of bulk precipitation decreases. The adsorption density for a monolayer coverage corresponds to the condensed state of an alkyl chain with a cross-sectional area of 33A˚2 (liquid-crystal state). Application of the two-dimensional condensation model is considered and no evidence for the surface precipitation process is observed.
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Mechanism of oleate interaction on salt-type minerals Part III. Adsorption, zeta potential and diffuse reflectance FT-IR studies of scheelite in the presence of sodium oleate
Colloids and Surfaces, 1991Co-Authors: K. Hanumantha Rao, K.s.e. ForssbergAbstract:The mechanism of oleate adsorption on scheelite has been examined through adsorption isotherms, zeta-potential measurements and diffuse reflectance FT-IR studies. The form of the adsorption isotherms for alkaline pH values indicated a Bilayered structure of oleate, proceeding the precipitation of calcium oleate. The precipitation of calcium oleate is characterized by a steep increase in the slope of the adsorption isotherms after 10 μmol m−2 adsorption density. This adsorption density corresponds to a condensed state of oleate molecule for a Bilayer Formation with a molecular coverage area of 33 A2 (liquid-crystal state). In the monolayer filling, monocoordination of oleate through counter sodium and calcium ions is suggested from the IR studies. A linear relationship between the amount adsorbed and the Kubelka-Munk function of diffuse reflectance is obtained. The zeta potentials are correlated to a successive oleate adsorption up to a Bilayer Formation. At high oleate concentrations, the constant negative zeta potentials ( − 52 mV) corresponds to that of calcium oleate, suggesting that the solids are covered with a layer of calcium oleate precipitate. Monocoordination of oleate through counter sodium and calcium ions in the monolayer range followed by a Bilayer Formation through hydrophobic association of hydrocarbon chains, prior to the growth of calcium oleate precipitate on the substrate, is suggested for the adsorption mechanism of oleate on scheelite.
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Mechanism of oleate interaction on salt-type minerals. V : Adsorption and precipitation reactions in relation to the solid/liquid ratio in the synthetic fluorite-sodium oleate system
Journal of Colloid and Interface Science, 1991Co-Authors: K. Hanumantha Rao, J M Cases, K.s.e. ForssbergAbstract:The mechanism of adsorption of oleate onto a synthetic fluorite sample at different solid/liquid ratios in alkaline solutions is elucidated through adsorption isotherms in conjunction with ζ-potential and diffuse reflectance Fourier transform-infrared spectroscopic studies. These studies show that the chemisorption of oleate on surface calcium species followed by the physical adsorption of hydrocarbon chains (Bilayer Formation) precede the precipitation of calcium oleate in bulk solution. With an increase in the solid/liquid ratio, the bulk precipitation of calcium oleate after Bilayer Formation is found to be reduced, and at a high solid concentration, the isotherm is seen to level off with Bilayer Formation. As the solid concentration increases, the concentration of calcium in bulk solution decreases because of its adsorption on the head group of the hydrophilic layer of oleate (Bilayer), and hence the extent of bulk precipitation decreases. The adsorption density for a monolayer coverage corresponds to the condensed state of an alkyl chain with a cross-sectional area of 33A˚2 (liquid-crystal state). Application of the two-dimensional condensation model is considered and no evidence for the surface precipitation process is observed.
Nam-joon Cho - One of the best experts on this subject based on the ideXlab platform.
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Supported Lipid Bilayer Formation: Beyond Vesicle Fusion
Langmuir, 2020Co-Authors: Joshua A. Jackman, Nam-joon ChoAbstract:Supported lipid Bilayers (SLBs) are cell-membrane-mimicking platforms that can be formed on solid surfaces and integrated with a wide range of surface-sensitive measurement techniques. SLBs are useful for unravelling details of fundamental membrane biology and biophysics as well as for various medical, biotechnology, and environmental science applications. Thus, there is high interest in developing simple and robust methods to fabricate SLBs. Currently, vesicle fusion is a popular method to form SLBs and involves the adsorption and spontaneous rupture of lipid vesicles on a solid surface. However, successful vesicle fusion depends on high-quality vesicle preparation, and it typically works with a narrow range of material supports and lipid compositions. In this Feature Article, we summarize current progress in developing two new SLB fabrication techniques termed the solvent-assisted lipid Bilayer (SALB) and bicelle methods, which have compelling advantages such as simple sample preparation and compatibility with a wide range of material supports and lipid compositions. The molecular self-assembly principles underpinning the two strategies and important experimental parameters are critically discussed, and recent application examples are presented. Looking forward, we envision that these emerging SLB fabrication strategies can be widely adopted by specialists and nonspecialists alike, paving the way to enriching our understanding of lipid membrane properties and realizing new application possibilities.
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a phenomenological model of the solvent assisted lipid Bilayer Formation method
Physical Chemistry Chemical Physics, 2016Co-Authors: Jurriaan J. J. Gillissen, Seyed R. Tabaei, Nam-joon ChoAbstract:The recently introduced solvent-assisted lipid Bilayer (SALB) Formation method allows one to efficiently fabricate planar, lipid Bilayers on solid supports and can be used for various applications. It involves the introduction of an aqueous buffer into a mixture of lipid and alcohol, which is incubated on a solid support. The associated phase changes in the ternary bulk system are accompanied by the Formation of a lipid Bilayer at the solid–liquid interface. While the phase behavior of the ternary bulk system is well understood, the mechanism of Bilayer assembly at the solid–liquid interface remains to be elucidated, including whether the adsorption process is limited by diffusion of the lipid in the bulk or by lipid binding kinetics onto the surface. Such factors strongly influence the success of Bilayer Formation as they pertain to operating conditions, such as lipid concentration, solvent exchange rate and chamber dimensions, and are hence of critical importance for SALB fabrication strategies. Herein, we extend an earlier proposed phenomenological kinetic model of the SALB Formation process, based on a volume-averaged treatment of the solvent mixing process. By comparing the model to quartz crystal microbalance with dissipation monitoring (QCM-D) experimental data, we conclude that SALB Formation is limited by diffusion of suspended lipid aggregates, with a hydrodynamic radius, that is consistent with aggregate size measurements in the literature. This agreement validates the proposed model to serve as the basis for optimizing conditions for SALB Formation.
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Nanoplasmonic ruler to measure lipid vesicle deFormation
Chemical communications (Cambridge England), 2016Co-Authors: Joshua A. Jackman, Barbora Špačková, Eric Linardy, Min Chul Kim, Bo Kyeong Yoon, Jiří Homola, Nam-joon ChoAbstract:A nanoplasmonic ruler method is presented in order to measure the deFormation of adsorbed, nm-scale lipid vesicles on solid supports. It is demonstrated that single adsorbed vesicles undergo greater deFormation on silicon oxide over titanium oxide, offering direct experimental evidence to support membrane tension-based theoretical models of supported lipid Bilayer Formation.
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Spatiotemporal dynamics of solvent-assisted lipid Bilayer Formation
Physical chemistry chemical physics : PCCP, 2015Co-Authors: Min Chul Kim, Jurriaan J. J. Gillissen, Seyed R. Tabaei, Vladimir P. Zhdanov, Nam-joon ChoAbstract:The solvent-assisted lipid Bilayer (SALB) method offers a general strategy to fabricate supported lipid Bilayers on solid surfaces. In this method, lipids dissolved in alcohol are deposited on the target substrate in parallel with their aggregation during exchange with aqueous buffer solution which promotes spontaneous Bilayer Formation. Herein, a combination of experimental and theoretical approaches is employed in order to understand the key aspects of the SALB Formation process. Epifluorescence microscopy experiments are conducted in order to measure the spatiotemporal dynamics of Bilayer Formation on a glass substrate in a microfluidic channel. Corresponding snapshots of Bilayer Formation at different stages are rationalized by a numerical simulation of solvent displacement inside the channel. Comparing simulation with experiment indicates that in close proximity to the side walls of the present setup, the Bilayer Formation is confined to a relatively thin region behind the moving solvent displacement front.
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Solvent-assisted lipid Bilayer Formation on silicon dioxide and gold.
Langmuir : the ACS journal of surfaces and colloids, 2014Co-Authors: Seyed R. Tabaei, Vladimir P. Zhdanov, Jae-hyeok Choi, Goh Haw Zan, Nam-joon ChoAbstract:Planar lipid Bilayers on solid supports mimic the fundamental structure of biological membranes and can be investigated using a wide range of surface-sensitive techniques. Despite these advantages, planar Bilayer fabrication is challenging, and there are no simple universal methods to form such Bilayers on diverse material substrates. One of the novel methods recently proposed and proven to form a planar Bilayer on silicon dioxide involves lipid deposition in organic solvent and solvent exchange to influence the phase of adsorbed lipids. To scrutinize the specifics of this solvent-assisted lipid Bilayer (SALB) Formation method and clarify the limits of its applicability, we have developed a simplified, continuous solvent-exchange version to form planar Bilayers on silicon dioxide, gold, and alkanethiol-coated gold (in the latter case, a lipid monolayer is formed to yield a hybrid Bilayer) and varied the type of organic solvent and rate of solvent exchange. By tracking the SALB Formation process with simul...
J M Cases - One of the best experts on this subject based on the ideXlab platform.
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mechanism of oleate interaction on salt type minerals v adsorption and precipitation reactions in relation to the solid liquid ratio in the synthetic fluorite sodium oleate system
Journal of Colloid and Interface Science, 1991Co-Authors: J M Cases, K.s.e. ForssbergAbstract:Abstract The mechanism of adsorption of oleate onto a synthetic fluorite sample at different solid/liquid ratios in alkaline solutions is elucidated through adsorption isotherms in conjunction with ζ-potential and diffuse reflectance Fourier transform-infrared spectroscopic studies. These studies show that the chemisorption of oleate on surface calcium species followed by the physical adsorption of hydrocarbon chains (Bilayer Formation) precede the precipitation of calcium oleate in bulk solution. With an increase in the solid/liquid ratio, the bulk precipitation of calcium oleate after Bilayer Formation is found to be reduced, and at a high solid concentration, the isotherm is seen to level off with Bilayer Formation. As the solid concentration increases, the concentration of calcium in bulk solution decreases because of its adsorption on the head group of the hydrophilic layer of oleate (Bilayer), and hence the extent of bulk precipitation decreases. The adsorption density for a monolayer coverage corresponds to the condensed state of an alkyl chain with a cross-sectional area of 33A˚2 (liquid-crystal state). Application of the two-dimensional condensation model is considered and no evidence for the surface precipitation process is observed.
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Mechanism of oleate interaction on salt-type minerals. V : Adsorption and precipitation reactions in relation to the solid/liquid ratio in the synthetic fluorite-sodium oleate system
Journal of Colloid and Interface Science, 1991Co-Authors: K. Hanumantha Rao, J M Cases, K.s.e. ForssbergAbstract:The mechanism of adsorption of oleate onto a synthetic fluorite sample at different solid/liquid ratios in alkaline solutions is elucidated through adsorption isotherms in conjunction with ζ-potential and diffuse reflectance Fourier transform-infrared spectroscopic studies. These studies show that the chemisorption of oleate on surface calcium species followed by the physical adsorption of hydrocarbon chains (Bilayer Formation) precede the precipitation of calcium oleate in bulk solution. With an increase in the solid/liquid ratio, the bulk precipitation of calcium oleate after Bilayer Formation is found to be reduced, and at a high solid concentration, the isotherm is seen to level off with Bilayer Formation. As the solid concentration increases, the concentration of calcium in bulk solution decreases because of its adsorption on the head group of the hydrophilic layer of oleate (Bilayer), and hence the extent of bulk precipitation decreases. The adsorption density for a monolayer coverage corresponds to the condensed state of an alkyl chain with a cross-sectional area of 33A˚2 (liquid-crystal state). Application of the two-dimensional condensation model is considered and no evidence for the surface precipitation process is observed.
Bengt Herbert Kasemo - One of the best experts on this subject based on the ideXlab platform.
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Vesicle Adsorption and Phospholipid Bilayer Formation on Topographically and Chemically Nanostructured Surfaces
The journal of physical chemistry. B, 2010Co-Authors: Indriati Pfeiffer, Sarunas Petronis, Bengt Herbert Kasemo, Ingo Köper, Michael ZächAbstract:We have investigated the influence of combined nanoscale topography and surface chemistry on lipid vesicle adsorption and supported Bilayer Formation on well-controlled model surfaces. To this end, we utilized colloidal lithography to nanofabricate pitted Au−SiO2 surfaces, where the top surface and the walls of the pits consisted of silicon dioxide whereas the bottom of the pits was made of gold. The diameter and height of the pits were fixed at 107 and 25 nm, respectively. Using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique and atomic force microscopy (AFM), we monitored the processes occurring upon exposure of these nanostructured surfaces to a solution of extruded unilamellar 1-palmitolyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles with a nominal diameter of 100 nm. To scrutinize the influence of surface chemistry, we studied two cases: (1) the bare gold surface at the bottom of the pits and (2) the gold passivated by biotinamidocaproyl-labeled bovine serum albu...
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Influence of nanotopography on phospholipid Bilayer Formation on silicon dioxide
The journal of physical chemistry. B, 2008Co-Authors: Indriati Pfeiffer, Bastien Seantier, Sarunas Petronis, Duncan S. Sutherland, Bengt Herbert Kasemo, Michael ZächAbstract:We have investigated the effect of well-defined nanoscale topography on the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid vesicle adsorption and supported phospholipid Bilayer (SPB) Formation on SiO2 surfaces using a quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). Unilamellar lipid vesicles with two different sizes, 30 and 100 nm, were adsorbed on pitted surfaces with two different pit diameters, 110 and 190 nm, as produced by colloidal lithography, and the behavior was compared to results obtained on flat surfaces. In all cases, complete Bilayer Formation was observed after a critical coverage of adsorbed vesicles had been reached. However, the kinetics of the vesicle-to-Bilayer transFormation, including the critical coverage, was significantly altered by surface topography for both vesicle sizes. Surface topography hampered the overall Bilayer Formation kinetics for the smaller vesicles, but promoted SPB Formation for the larger vesicles...
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intact vesicle adsorption and supported biomembrane Formation from vesicles in solution influence of surface chemistry vesicle size temperature and osmotic pressure
Langmuir, 2003Co-Authors: Erik Reimhult, Fredrik Höök, Bengt Herbert KasemoAbstract:The adsorption kinetics of small unilamellar egg-yolk phosphatidylcholine vesicles was investigated by the quartz crystal microbalance−dissipation (QCM−D) technique, as a function of surface chemistry (on SiO2, Si3N4, Au, TiO2, and Pt), temperature (273−303 K), vesicle size (25−200 nm), and osmotic pressure. On SiO2 and Si3N4, the vesicles adsorb intact at low coverage, followed by transFormation to a Bilayer at a critical coverage. On TiO2, oxidized Pt, and oxidized Au, the vesicles adsorb intact at all coverages and all studied temperatures. Variation of vesicle size does not change the qualitative behavior on any of the surfaces, but the quantitative differences provide important inFormation about surface-induced vesicle deFormation. In the low-coverage regime (where vesicles adsorb intact on all surfaces), the deFormation is much larger on SiO2 than on the surfaces where Bilayer Formation does not occur. This is attributed to stronger vesicle−surface interaction on SiO2. The Bilayer Formation is therm...
Bernard Desbat - One of the best experts on this subject based on the ideXlab platform.
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Unexpected Bilayer Formation in Langmuir films of nucleolipids.
Langmuir : the ACS journal of surfaces and colloids, 2012Co-Authors: Bernard Desbat, Nessim Arazam, Giovanni Tonelli, Wilfrid Néri, Salim Khiati, Philippe Barthélémy, Laurence NavaillesAbstract:Langmuir monolayers have been extensively investigated by various experimental techniques. These studies allowed an in-depth understanding of the molecular conFormation in the layer, phase transitions, and the structure of the multilayer. As the monolayer is compressed and the surface pressure is increased beyond a critical value, usually occurring in the minimal closely packed molecular area, the monolayer fractures and/or folds, forming multilayers in a process referred to as collapse. Various mechanisms for monolayer collapse and the resulting reorganization of the film have been proposed, and only a few studies have demonstrated the Formation of a Bilayer after collapse and with the use of a Ca2+ solution. In this work, Langmuir isotherms coupled with imaging ellipsometry and polarization modulation infrared reflection absorption spectroscopy were recorded to investigate the air–water interface properties of Langmuir films of anionic nucleolipids. We report for these new molecules the Formation of a q...
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Unexpected Bilayer Formation in langmuir films of nucleolipids
2012Co-Authors: Bernard Desbat, Nessim Arazam, Giovanni Tonelli, Wilfrid Néri, Salim Khiati, Philippe Barthélémy, Laurence NavaillesAbstract:Langmuir monolayers have been extensively investigated by various experimental techniques. These studies allowed an in-depth understanding of the molecular conFormation in the layer, phase transitions, and the structure of the multilayer. As the monolayer is compressed and the surface pressure is increased beyond a critical value, usually occurring in the minimal closely packed molecular area, the monolayer fractures and/or folds, forming multilayers in a process referred to as collapse. Various mechanisms for monolayer collapse and the resulting reorganization of the film have been proposed, and only a few studies have demonstrated the Formation of a Bilayer after collapse and with the use of a Ca(2+) solution. In this work, Langmuir isotherms coupled with imaging ellipsometry and polarization modulation infrared reflection absorption spectroscopy were recorded to investigate the air-water interface properties of Langmuir films of anionic nucleolipids. We report for these new molecules the Formation of a quasi-hexagonal packing of Bilayer domains at a low compression rate, a singular behavior for lipids at the air-water interface that has not yet been documented.
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Asymmetric lipid Bilayer Formation stabilized by DNA at the air/water interface
Biochimie, 2009Co-Authors: Sabine Castano, Brigitte Delord, Annie Février, Jean-marie Lehn, Pierre Lehn, Bernard DesbatAbstract:The lipid bis(guanidinium)-tren-cholesterol (BGTC) is a cationic cholesterol derivative bearing guanidinium polar headgroups used for gene transfection either alone or formulated as liposomes with the zwitterionic lipid 1,2-di-[cis-9-octadecenoyl]-sn-glycero 3-phosphoethanolamine (DOPE). Previous investigations have shown its ability to strongly interact with DNA and form asymmetric lipid Bilayers at the air/water interface when mixed with DOPE. Here, with a view to further investigate its physicochemical behavior, we studied the interactions of mixtures of BGTC with another zwitterionic lipid, 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine, (DMPC), with DNA at the air/water interface by using the Langmuir monolayer technique coupled with Brewster Angle Microscopy (BAM) and Polarization Modulation Infra Red Reflexion Absorption (PMIRRAS) spectroscopy and we investigate DNA–BGTC/ DMPC interactions. We demonstrate that when DNA is injected into the subphase in excess compared to the positive charges of BGTC, it adsorbs to BGTC/DMPC monolayers at 20 mN/m whatever the lipid monolayer composition (1/5, 2/3 or 3/2 BGTC/DMPC molar ratio) and forms an incomplete monolayer of either isotropic or anisotropic double strands depending on the BGTC content in the monolayer. Compression beyond the collapse of some mixed DNA–BGTC/DMPC (2/3 and 3/2 molar ratio) systems leads to the Formation of DNA monolayers underneath asymmetric lipid Bilayers characterized by a bottom layer of BGTC in contact with DNA and a top layer mainly constituted of DMPC.