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Nagao M, Seto H. Neutron scattering studies on dynamics of lipid membranes. BIOPHYSICS REVIEWS 2023; 4:021306. [PMID: 38504928 PMCID: PMC10903442 DOI: 10.1063/5.0144544] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 05/01/2023] [Indexed: 03/21/2024]
Abstract
Neutron scattering methods are powerful tools for the study of the structure and dynamics of lipid bilayers in length scales from sub Å to tens to hundreds nm and the time scales from sub ps to μs. These techniques also are nondestructive and, perhaps most importantly, require no additives to label samples. Because the neutron scattering intensities are very different for hydrogen- and deuterium-containing molecules, one can replace the hydrogen atoms in a molecule with deuterium to prepare on demand neutron scattering contrast without significantly altering the physical properties of the samples. Moreover, recent advances in neutron scattering techniques, membrane dynamics theories, analysis tools, and sample preparation technologies allow researchers to study various aspects of lipid bilayer dynamics. In this review, we focus on the dynamics of individual lipids and collective membrane dynamics as well as the dynamics of hydration water.
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Affiliation(s)
| | - Hideki Seto
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
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2
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Nagao M, Bradbury R, Ansar SM, Kitchens CL. Effect of gold nanoparticle incorporation into oil-swollen surfactant lamellar membranes. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:065102. [PMID: 33344674 PMCID: PMC7744122 DOI: 10.1063/4.0000041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 11/25/2020] [Indexed: 05/08/2023]
Abstract
An oil-swollen surfactant membrane is employed to measure the effects of incorporated hydrophobically functionalized gold nanoparticles (AuNPs) on the structure and dynamics of the membranes. While maintaining an average AuNP diameter of approximately 5 nm, the membrane thickness was varied from 5 nm to 7.5 nm by changing the amount of oil in the membrane. The membranes become softer as the proportion of oil is increased, while the thickness fluctuations become slower. We attribute this to an increased fluctuation wavelength. Incorporation of AuNPs in the membrane induces membrane thinning and softening. Oil molecules surround the nanoparticles in the membrane and help their relatively homogeneous distribution. AuNPs significantly alter the membrane's structure and dynamics through thinning of the membrane, increased compressibility, and possible diffusion of AuNPs inside the membrane.
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Affiliation(s)
| | | | - Siyam M. Ansar
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Christopher L. Kitchens
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
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Frenzel L, Lehmkühler F, Lokteva I, Narayanan S, Sprung M, Grübel G. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett 2019; 10:5231-5236. [PMID: 31433650 DOI: 10.1021/acs.jpclett.9b01690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We present the structure and dynamics of highly concentrated core-shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell suspended in water. With X-ray photon correlation spectroscopy, we are able to follow dynamical changes over the volume phase transition of PNIPAm at LCST = 32 °C. On raising the temperature beyond LCST, the structural relaxation times continue to decrease. The effect is accompanied by a transition from stretched to compressed exponential shape of the intensity autocorrelation function. Upon further heating, we find a sudden slowing down for the particles in their collapsed state. The q dependence of the relaxation time shows an anomalous change from τc ∝ q-3 to τc ∝ q-1. Small angle X-ray scattering data evidence a temperature-induced transition from repulsive to attractive forces. Our results indicate a temperature-induced phase transition from a colloidal liquid with polymer-driven dynamics toward a colloidal gel.
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Affiliation(s)
- Lara Frenzel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Felix Lehmkühler
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Irina Lokteva
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Suresh Narayanan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Michael Sprung
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Gerhard Grübel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
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Gupta S, De Mel JU, Perera RM, Zolnierczuk P, Bleuel M, Faraone A, Schneider GJ. Dynamics of Phospholipid Membranes beyond Thermal Undulations. J Phys Chem Lett 2018; 9:2956-2960. [PMID: 29754484 DOI: 10.1021/acs.jpclett.8b01008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We investigated the molecular dynamics of unilamellar liposomes by neutron spin echo spectroscopy. We report the first experimental evidence of a short-range motion at the length scale of the size of the headgroup of a lipid. The associated mean squared displacement shows a t0.26 dependence in the pico- to nanosecond region that indicates another process beyond the predictions of the Zilman-Granek (ZG) model ( t0.66) and translational diffusion ( t1). A comparison with theory shows that the observed low exponent is associated with a non-Gaussian transient trapping of lipid molecules in a local area and supports the continuous time random walk model. The analysis of the mean squared displacement leads to the important conclusion that the friction at the interface between water and liposomes plays a minor role. Center of mass diffusion of liposomes and transient trapping of lipids define the range in which the ZG model can be applied to analyze membrane fluctuations.
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Affiliation(s)
- Sudipta Gupta
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Judith U De Mel
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Rasangi M Perera
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Piotr Zolnierczuk
- Jülich Centre for Neutron Science (JCNS), Outstation at SNS, POB 2008, 1 Bethel Valley Road , Oak Ridge , Tennessee 37831 , United States
| | - Markus Bleuel
- NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899-6100 , United States
| | - Antonio Faraone
- NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899-6100 , United States
| | - Gerald J Schneider
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
- Department of Physics & Astronomy , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
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Hoffmann I, Hoffmann C, Farago B, Prévost S, Gradzielski M. Dynamics of small unilamellar vesicles. J Chem Phys 2018; 148:104901. [DOI: 10.1063/1.5009424] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Ingo Hoffmann
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany
- Institut Max von Laue-Paul Langevin (ILL), 71 Avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9, France
| | - Claudia Hoffmann
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany
| | - Bela Farago
- Institut Max von Laue-Paul Langevin (ILL), 71 Avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9, France
| | - Sylvain Prévost
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany
- Institut Max von Laue-Paul Langevin (ILL), 71 Avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9, France
- Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
| | - Michael Gradzielski
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany
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6
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Kawabata Y, Bradbury R, Kugizaki S, Weigandt K, Melnichenko YB, Sadakane K, Yamada NL, Endo H, Nagao M, Seto H. Effect of interlamellar interactions on shear induced multilamellar vesicle formation. J Chem Phys 2017; 147:034905. [PMID: 28734290 DOI: 10.1063/1.4994563] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Shear-induced multilamellar vesicle (MLV) formation has been studied by coupling the small-angle neutron scattering (SANS) technique with neutron spin echo (NSE) spectroscopy. A 10% mass fraction of the nonionic surfactant pentaethylene glycol dodecyl ether (C12E5) in water was selected as a model system for studying weak inter-lamellar interactions. These interactions are controlled either by adding an anionic surfactant, sodium dodecyl sulfate, or an antagonistic salt, rubidium tetraphenylborate. Increasing the charge density in the bilayer induces an enhanced ordering of the lamellar structure. The charge density dependence of the membrane bending modulus was determined by NSE and showed an increasing trend with charge. This behavior is well explained by a classical theoretical model. By considering the Caillé parameters calculated from the SANS data, the layer compressibility modulus B¯ is estimated and the nature of the dominant inter-lamellar interaction is determined. Shear flow induces MLV formation around a shear rate of 10 s-1, when a small amount of charge is included in the membrane. The flow-induced layer undulations are in-phase between neighboring layers when the inter-lamellar interaction is sufficiently strong. Under these conditions, MLV formation can occur without significantly changing the inter-lamellar spacing. On the other hand, in the case of weak inter-lamellar interactions, the flow-induced undulations are not in-phase, and greater steric repulsion leads to an increase in the inter-lamellar spacing with shear rate. In this case, MLV formation occurs as the amplitude of the undulations gets larger and the steric interaction leads to in-phase undulations between neighboring membranes.
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Affiliation(s)
- Y Kawabata
- Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - R Bradbury
- Center for Exploration of Energy and Matter, Department of Physics, Indiana University, Bloomington, Indiana 47408, USA
| | - S Kugizaki
- Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - K Weigandt
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - Y B Melnichenko
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA
| | - K Sadakane
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
| | - N L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai 319-1106, Japan
| | - H Endo
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai 319-1106, Japan
| | - M Nagao
- Center for Exploration of Energy and Matter, Department of Physics, Indiana University, Bloomington, Indiana 47408, USA
| | - H Seto
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai 319-1106, Japan
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7
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Bradbury R, Nagao M. Effect of charge on the mechanical properties of surfactant bilayers. SOFT MATTER 2016; 12:9383-9390. [PMID: 27830216 DOI: 10.1039/c6sm01686c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Charge effects on the mechanical properties of surfactant bilayers have been measured, for a system with a low ionic strength, using small-angle neutron scattering and neutron spin echo spectroscopy. We report that, not only does increasing the surface charge density lead to greater structural ordering and a stiffening of the membrane, which is consistent with classical theory of charge effects on membranes, but also that the relaxation rate of the membrane thickness fluctuations decreases without affecting the fluctuation amplitude. From the relaxation rate we demonstrate, using recent theory, that the viscosity of the surfactant membrane is increased with surface charge density, which suggests that the amount of charge controls the diffusion behavior of inclusions inside the membrane. The present results confirm that the thickness fluctuation relaxation rate and amplitude are tuned independently since the membrane viscosity is only influencing the relaxation rate. This work demonstrates that charge stabilization of lamellar bilayers is not merely affected by intermembrane interactions and structural ordering but that intramembrane dynamics also have a significant contribution.
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Affiliation(s)
- Robert Bradbury
- Center for Exploration of Energy and Matter, Department of Physics, Indiana University, Bloomington, Indiana, USA. and National Institute of Standards and Technology Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland, USA
| | - Michihiro Nagao
- Center for Exploration of Energy and Matter, Department of Physics, Indiana University, Bloomington, Indiana, USA. and National Institute of Standards and Technology Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland, USA
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Hickey RJ, Gillard TM, Irwin MT, Lodge TP, Bates FS. Structure, viscoelasticity, and interfacial dynamics of a model polymeric bicontinuous microemulsion. SOFT MATTER 2016; 12:53-66. [PMID: 26439750 DOI: 10.1039/c5sm02009c] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have systematically studied the equilibrium structure and dynamics of a polymeric bicontinuous microemulsion (BμE) composed of poly(cyclohexylethylene) (PCHE), poly(ethylene) (PE), and a volumetrically symmetric PCHE-PE diblock copolymer, using dynamic mechanical spectroscopy, small angle X-ray and neutron scattering, and transmission electron microscopy. The BμE was investigated over an 80 °C temperature range, revealing a structural evolution and a rheological response not previously recognized in such systems. As the temperature is reduced below the point associated with the lamellar-disorder transition at compositions adjacent to the microemulsion channel, the interfacial area per chain of the BμE approaches that of the neat (undiluted) lamellar diblock copolymer. With increasing temperature, the diblock-rich interface swells through homopolymer infiltration. Time-temperature-superposed linear dynamic data obtained as a function of frequency show that the viscoelastic response of the BμE is strikingly similar to that of the fluctuating pure diblock copolymer in the disordered state, which we associate with membrane undulations and the breaking and reforming of interfaces. This work provides new insights into the structure and dynamics that characterize thermodynamically stable BμEs in the limits of relatively weak and strong segregation.
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Affiliation(s)
- Robert J Hickey
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Timothy M Gillard
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Matthew T Irwin
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Timothy P Lodge
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA and Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Frank S Bates
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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9
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Pan J, Cheng X, Sharp M, Ho CS, Khadka N, Katsaras J. Structural and mechanical properties of cardiolipin lipid bilayers determined using neutron spin echo, small angle neutron and X-ray scattering, and molecular dynamics simulations. SOFT MATTER 2015; 11:130-138. [PMID: 25369786 DOI: 10.1039/c4sm02227k] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The detailed structural and mechanical properties of a tetraoleoyl cardiolipin (TOCL) bilayer were determined using neutron spin echo (NSE) spectroscopy, small angle neutron and X-ray scattering (SANS and SAXS, respectively), and molecular dynamics (MD) simulations. We used MD simulations to develop a scattering density profile (SDP) model, which was then utilized to jointly refine SANS and SAXS data. In addition to commonly reported lipid bilayer structural parameters, component distributions were obtained, including the volume probability, electron density and neutron scattering length density. Of note, the distance between electron density maxima DHH (39.4 Å) and the hydrocarbon chain thickness 2DC (29.1 Å) of TOCL bilayers were both found to be larger than the corresponding values for dioleoyl phosphatidylcholine (DOPC) bilayers. Conversely, TOCL bilayers have a smaller overall bilayer thickness DB (36.7 Å), primarily due to their smaller headgroup volume per phosphate. SDP analysis yielded a lipid area of 129.8 Å(2), indicating that the cross-sectional area per oleoyl chain in TOCL bilayers (i.e., 32.5 Å(2)) is smaller than that for DOPC bilayers. Multiple sets of MD simulations were performed with the lipid area constrained at different values. The calculated surface tension versus lipid area resulted in a lateral area compressibility modulus KA of 342 mN m(-1), which is slightly larger compared to DOPC bilayers. Model free comparison to experimental scattering data revealed the best simulated TOCL bilayer from which detailed molecular interactions were determined. Specifically, Na(+) cations were found to interact most strongly with the glycerol hydroxyl linkage, followed by the phosphate and backbone carbonyl oxygens. Inter- and intra-lipid interactions were facilitated by hydrogen bonding between the glycerol hydroxyl and phosphate oxygen, but not with the backbone carbonyl. Finally, analysis of the intermediate scattering functions from NSE spectroscopy measurements of TOCL bilayers yielded a bending modulus KC of 1.06 × 10(-19) J, which was larger than that observed in DOPC bilayers. Our results show the physicochemical properties of cardiolin bilayers that may be important in explaining their functionality in the inner mitochondrial membrane.
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Affiliation(s)
- Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL 33620, USA.
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Mell M, Moleiro LH, Hertle Y, López-Montero I, Cao FJ, Fouquet P, Hellweg T, Monroy F. Fluctuation dynamics of bilayer vesicles with intermonolayer sliding: experiment and theory. Chem Phys Lipids 2014; 185:61-77. [PMID: 25455136 DOI: 10.1016/j.chemphyslip.2014.11.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/24/2014] [Accepted: 11/27/2014] [Indexed: 10/24/2022]
Abstract
The presence of coupled modes of membrane motion in closed shells is extensively predicted by theory. The bilayer structure inherent to lipid vesicles is suitable to support hybrid modes of curvature motion coupling membrane bending with the local reorganization of the bilayer material through relaxation of the dilatational stresses. Previous experiments evidenced the existence of such hybrid modes facilitating membrane bending at high curvatures in lipid vesicles [Rodríguez-García, R., Arriaga, L.R., Mell, M., Moleiro, L.H., López-Montero, I., Monroy, F., 2009. Phys. Rev. Lett. 102, 128201.]. For lipid bilayers that are able to undergo intermonolayer sliding, the experimental fluctuation spectra are found compatible with a bimodal schema. The usual tension/bending fluctuations couple with the hybrid modes in a mechanical interplay, which becomes progressively efficient with increasing vesicle radius, to saturate at infinity radius into the behavior expected for a flat membrane. Grounded on the theory of closed shells, we propose an approximated expression of the bimodal spectrum, which predicts the observed dependencies on the vesicle radius. The dynamical features obtained from the autocorrelation functions of the vesicle fluctuations are found in quantitative agreement with the proposed theory.
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Affiliation(s)
- Michael Mell
- Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Lara H Moleiro
- Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain; Physikalische Chemie I, Univeristät Bayreuth, Universitätsstraße 30, D-95447 Bayreuth, Germany
| | - Yvonne Hertle
- Physikalische und Biophysikalische Chemie I, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany
| | - Iván López-Montero
- Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Francisco J Cao
- Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Peter Fouquet
- TOF/HR Group, Institut Laue Langevin, 6 Rue Jules Horowitz, BP156, F-38042 Grenoble Cedex 9, France
| | - Thomas Hellweg
- Physikalische und Biophysikalische Chemie I, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany
| | - Francisco Monroy
- Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
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12
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Hoffmann I, Michel R, Sharp M, Holderer O, Appavou MS, Polzer F, Farago B, Gradzielski M. Softening of phospholipid membranes by the adhesion of silica nanoparticles--as seen by neutron spin-echo (NSE). NANOSCALE 2014; 6:6945-52. [PMID: 24838980 DOI: 10.1039/c4nr00774c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.
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Affiliation(s)
- Ingo Hoffmann
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany.
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13
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Hirai M, Kimura R, Takeuchi K, Sugiyama M, Kasahara K, Ohta N, Farago B, Stadler A, Zaccai G. Change of dynamics of raft-model membrane induced by amyloid-β protein binding. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:74. [PMID: 23852578 DOI: 10.1140/epje/i2013-13074-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 02/25/2013] [Accepted: 04/22/2013] [Indexed: 06/02/2023]
Abstract
While the steady-state existence in the size and shape of liquid-ordered microdomains in cell membranes, the so-called "lipid rafts", still remain the subject of debate, glycosphingolipid-cholesterol rich regions in plasma membranes have been considered to have a function as platforms for signaling and sorting. In addition, recent spectroscopic studies show that the interaction between monosialoganglioside and amyloid beta (Aβ protein promotes the transition of Aβ from the native structure to the cross-beta fold in amyloid aggregates. However, there is few evidence on the dynamics of "lipid rafts" membranes. As the neutron spin-echo (NSE) technique is well known to detect directly slow dynamics of membrane systems in situ, by the combination of NSE and small-angle X-ray scattering we have studied the effect of the interaction between raft-model membrane and amyloid Aβ proteins on the structure and dynamics of a large uni-lamellar vesicle (LUV) consisting of monosialoganglioside-cholesterol-phospholipid ternary mixtures as a model of lipid-raft membrane. We have found that the interaction between the Aβ proteins and the model membrane at the liquid crystal phase significantly suppresses a bending-diffusion motion with a minor effect on the LUV structure. The present results would suggest a possibility of non-receptor-mediated disorder in signaling through a modulation of a membrane dynamics induced by the association of amyloidogenic peptides on a plasma membrane.
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Mell M, Moleiro LH, Hertle Y, Fouquet P, Schweins R, López-Montero I, Hellweg T, Monroy F. Bending stiffness of biological membranes: what can be measured by neutron spin echo? THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:75. [PMID: 23852577 DOI: 10.1140/epje/i2013-13075-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 04/10/2013] [Accepted: 05/21/2013] [Indexed: 06/02/2023]
Abstract
Large vesicles obtained by the extrusion method represent adequate membrane models to probe membrane dynamics with neutron radiation. Particularly, the shape fluctuations around the spherical average topology can be recorded by neutron spin echo (NSE). In this paper we report on the applicable theories describing the scattering contributions from bending-dominated shape fluctuations in diluted vesicle dispersions, with a focus on the relative relevance of the master translational mode with respect to the internal fluctuations. Different vesicle systems, including bilayer and non-bilayer membranes, have been scrutinized. We describe the practical ranges where the exact theory of bending fluctuations is applicable to obtain the values of the bending modulus from experiments, and we discuss about the possible internal modes that could be alternatively contributing to shape fluctuations.
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Affiliation(s)
- Michael Mell
- Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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Hoffmann I, Heunemann P, Farago B, Grillo I, Holderer O, Päch M, Gradzielski M. Structure and dynamics of nanoemulsions: insights from combining dynamic and static neutron scattering. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:061407. [PMID: 23367950 DOI: 10.1103/physreve.86.061407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Indexed: 06/01/2023]
Abstract
Despite their lack of thermodynamical stability, nanoemulsions can show a remarkable degree of kinetic stability. Among the various different preparation methods the phase-inversion concentration method is particularly interesting as it occurs spontaneously. Here we investigate such a system composed of a surfactant, cosurfactant, and oil that upon dilution with water forms long time metastable oil-in-water nanoemulsion droplets. The dynamics of the amphiphilic monolayers and its elastic properties is important for their stability and therefore the monolayer dynamics have been investigated by neutron spin echo (NSE). Despite the difficulties arising from the inherently polydisperse nature and the large number of different components necessarily contained in commercial nanoemulsion formulations, information concerning the membrane rigidity was extracted from the combination of small angle neutron scattering and NSE and several different formulations are compared. These results show that small amounts of different admixed ionic surfactants can modify the monolayer rigidity substantially and similarly effects of surface bound polyelectrolytes have been evaluated.
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Affiliation(s)
- I Hoffmann
- Institut Max von Laue-Paul Langevin, F-38042 Grenoble Cedex 9, France.
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Watson MC, Peng Y, Zheng Y, Brown FLH. The intermediate scattering function for lipid bilayer membranes: from nanometers to microns. J Chem Phys 2012; 135:194701. [PMID: 22112091 DOI: 10.1063/1.3657857] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A numerical scheme based upon established hydrodynamic and elastic considerations is introduced and used to predict the intermediate scattering function for lipid bilayer membranes. The predictions span multiple wavelength regimes, including those studied by dynamic light scattering (DLS; microns) and neutron spin-echo (NSE) spectroscopy (10-100 nm). The results validate a recent theory specific to the NSE regime and expose slight inaccuracies associated with the theoretical results available in the DLS regime. The assumptions that underlie both our numerical methods and the related theoretical predictions are reviewed in detail to explain when certain results can be applied to experiment and where caution must be exercised.
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Affiliation(s)
- Max C Watson
- Department of Physics, University of California, Santa Barbara, California 93106, USA.
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17
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Nagao M. Temperature and scattering contrast dependencies of thickness fluctuations in surfactant membranes. J Chem Phys 2011; 135:074704. [PMID: 21861581 DOI: 10.1063/1.3625434] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Temperature and scattering contrast dependencies of thickness fluctuations have been investigated using neutron spin echo spectroscopy in a swollen lamellar phase composed of nonionic surfactant, water, and oil. In the present study, two contrast conditions are examined; one is the bulk contrast, which probes two surfactant monolayers with an oil layer as a membrane, and the other is the film contrast, which emphasizes an individual surfactant monolayer. The thickness fluctuations enhance dynamics from the bending fluctuations, and are observed in a similar manner in both contrast conditions. Thickness fluctuations can be investigated regardless of the scattering contrast, though film contrasts are better to be employed in terms of the data quality. The thickness fluctuation amplitude is constant over the measured temperature range, including in the vicinity of the phase boundary between the lamellar and micellar phases at low temperature and the boundary between the lamellar and bicontinuous phases at high temperature. The damping frequency of the thickness fluctuations is well scaled using viscosity within the membranes at low temperature, which indicates the thickness fluctuations are predominantly controlled by the viscosity within the membrane. On the other hand, in the vicinity of the phase boundary at high temperature, thickness fluctuations become faster without changing the mode amplitude.
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Affiliation(s)
- Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA.
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18
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Wellert S, Karg M, Holderer O, Richardt A, Hellweg T. Temperature dependence of the surfactant film bending elasticity in a bicontinuous sugar surfactant based microemulsion: a quasielastic scattering study. Phys Chem Chem Phys 2011; 13:3092-9. [DOI: 10.1039/c0cp02044c] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Holderer O, Klostermann M, Monkenbusch M, Schweins R, Lindner P, Strey R, Richter D, Sottmann T. Soft fluctuating surfactant membranes in supercritical CO2-microemulsions. Phys Chem Chem Phys 2011; 13:3022-5. [DOI: 10.1039/c0cp01199a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Wellert S, Altmann HJ, Richardt A, Lapp A, Falus P, Farago B, Hellweg T. Dynamics of the interfacial film in bicontinuous microemulsions based on a partly ionic surfactant mixture: A neutron spin-echo study. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 33:243-250. [PMID: 21061040 DOI: 10.1140/epje/i2010-10668-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 08/03/2010] [Accepted: 10/12/2010] [Indexed: 05/30/2023]
Abstract
In a microemulsion system based on a mixture of nonionic and ionic surfactants the addition of alcohol instead of changing the temperature was used to tune the curvature of the surfactant interface. The influence of the addition of the short-chain alcohol 2-propanol in the system water-perchloroethylene- Marlowet IHF-2-propanol is studied using neutron spin-echo spectroscopy. In contrast to alcohols with long alkyl chains 2-propanol is no strong co-surfactant, but changes the properties of the solvents. The present contribution focuses on the bicontinuous phase in this system and a quantitative analysis of the obtained neutron spin-echo data is proposed within the theoretical framework given by Zilman and Granek for amphiphilic membranes. It turns out that, in addition to the local movements of the surfactant film, also a collective diffusional mode of the bicontinuous structure has to be taken into account. The presented approach allows to calculate the bending elastic constant κ of the film. The approach is subsequently applied to follow changes of κ as induced by changes of the alcohol concentration.
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Affiliation(s)
- S Wellert
- Helmholtz-Center Berlin for Energy and Materials, Berlin, Germany
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21
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Brandt EG, Edholm O. Stretched exponential dynamics in lipid bilayer simulations. J Chem Phys 2010; 133:115101. [DOI: 10.1063/1.3478998] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Watson MC, Brown FLH. Interpreting membrane scattering experiments at the mesoscale: the contribution of dissipation within the bilayer. Biophys J 2010; 98:L9-L11. [PMID: 20303849 DOI: 10.1016/j.bpj.2009.11.026] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 11/14/2009] [Accepted: 11/18/2009] [Indexed: 10/19/2022] Open
Abstract
Neutron spin-echo spectroscopy provides a means to study membrane undulation dynamics over length scales roughly spanning 10-100 nanometers. Modern interpretation of these measurements relies on the theoretical predictions of Zilman and Granek; however, it is necessary to introduce an anomalously large solvent viscosity within this theory to obtain quantitative agreement with experiment. An extended theoretical treatment is presented that includes the effects of internal dissipation within the bilayer. Within the length and time regimes appropriate to neutron spin-echo experiments, the results of Zilman and Granek are largely recovered, except that the bilayer curvature modulus kappa appearing in their theory must be replaced with an effective dynamic curvature modulus kappa =kappa+2d(2)k(m), where d is a distance comparable to the monolayer thickness (the height of the neutral surface from bilayer midplane) and k(m) is the monolayer compressibility modulus. Direct comparison between theory and experiment becomes possible without any rescaling of physical parameters.
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Affiliation(s)
- Max C Watson
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA.
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Nagao M. Observation of local thickness fluctuations in surfactant membranes using neutron spin echo. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:031606. [PMID: 19905122 DOI: 10.1103/physreve.80.031606] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 08/14/2009] [Indexed: 05/24/2023]
Abstract
Experimental evidence of local thickness fluctuations of a surfactant membrane, as observed by neutron scattering, is reported. A swollen lamellar structure consisting of nonionic surfactant, water, and oil was investigated by neutron spin echo spectroscopy. Different dynamical processes are recognized at three different length scales. At length scales larger than the membrane thickness, the bending motion is observed, which follows the Zilman and Granek theory [Phys. Rev. Lett. 77, 4788 (1996)]. At the length scale corresponding to the membrane thickness, a clear excess dynamics in addition to the bending motion is observed. This mode is interpreted as the local thickness fluctuations. At even shorter length scales, smaller than the membrane thickness, intramembrane dynamics such as protrusion motions may have been observed.
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Affiliation(s)
- Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA.
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25
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Yi Z, Nagao M, Bossev DP. Bending elasticity of saturated and monounsaturated phospholipid membranes studied by the neutron spin echo technique. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:155104. [PMID: 21825357 DOI: 10.1088/0953-8984/21/15/155104] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have used neutron spin echo (NSE) spectroscopy to study the effect of bilayer thickness and monounsaturation (existence of a single double bond on one of the aliphatic chains) on the physical properties of unilamellar vesicles. The bending elasticity of saturated and monounsaturated phospholipid bilayers made of phospholipids with alkyl chain length ranging from 14 to 20 carbons was investigated. The bending elasticity κ(c) of phosphatidylcholines (PCs) in the liquid crystalline (L(α)) phase ranges from 0.38 × 10(-19) J for 1,2-dimyristoyl-sn-glycero-3-phosphocholine to 0.64 × 10(-19) J for 1,2-dieicosenoyl-sn-glycero-3-phosphocholine. It was confirmed that, contrary to the strong effect on the main transition temperature, the monounsaturation has a limited influence on the bending elasticity of lipid bilayers. In addition, when the area modulus K(A) varies little with chain unsaturation or length, the elastic ratios (κ(c)/K(A))(1/2) of saturated and monounsaturated phospholipid bilayers varies linearly with lipid hydrophobic thickness d which agrees well with the theory of ideal fluid membranes.
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Affiliation(s)
- Zheng Yi
- Physics Department, Indiana University, Bloomington, IN 47405, USA. Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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26
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Seto H, Yamada NL, Nagao M, Hishida M, Takeda T. Bending modulus of lipid bilayers in a liquid-crystalline phase including an anomalous swelling regime estimated by neutron spin echo experiments. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2008; 26:217-223. [PMID: 18446269 DOI: 10.1140/epje/i2007-10315-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 03/17/2008] [Indexed: 05/26/2023]
Abstract
Membrane fluctuations of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) were investigated by neutron spin echo spectroscopy. The intermediate structure factor was analyzed in terms of the model proposed by Zilman and Granek (Phys. Rev. Lett. 77, 4788 (1996)), and the bending modulus of lipid bilayers was derived. The hardening of a lipid bilayer upon approaching the main transition point in the anomalous swelling regime was observed, which naturally connects the bending modulus in the gel phase below the main transition temperature.
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Affiliation(s)
- H Seto
- Department of Physics, Kyoto University, Kyoto, Japan.
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27
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Miyake M, Asano A, Einaga Y. Size Change of the Wormlike Micelles of Pentaoxyethylene, Hexaoxyethylene, and Heptaoxyethylene Dodecyl Ethers with Uptake of n-Dodecane. J Phys Chem B 2008; 112:4648-55. [DOI: 10.1021/jp7110742] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maiko Miyake
- Department of Chemistry, Nara Women's University, Nara 630-8506, Japan
| | - Ayako Asano
- Department of Chemistry, Nara Women's University, Nara 630-8506, Japan
| | - Yoshiyuki Einaga
- Department of Chemistry, Nara Women's University, Nara 630-8506, Japan
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28
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Brinker KL, Mochrie SGJ, Burghardt WR. Equilibrium Dynamics of a Polymer Bicontinuous Microemulsion. Macromolecules 2007. [DOI: 10.1021/ma0704820] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kristin L. Brinker
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208; Department of Physics, Yale University, New Haven, Connecticut 06520; and Department of Chemical and Biological Engineering and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208
| | - Simon G. J. Mochrie
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208; Department of Physics, Yale University, New Haven, Connecticut 06520; and Department of Chemical and Biological Engineering and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208
| | - Wesley R. Burghardt
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208; Department of Physics, Yale University, New Haven, Connecticut 06520; and Department of Chemical and Biological Engineering and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208
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29
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Holderer O, Frielinghaus H, Monkenbusch M, Allgaier J, Richter D, Farago B. Hydrodynamic effects in bicontinuous microemulsions measured by inelastic neutron scattering. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2007; 22:157-61. [PMID: 17356800 DOI: 10.1140/epje/e2007-00021-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Indexed: 05/14/2023]
Abstract
The dynamical properties of bicontinuous microemulsions have been studied with neutron spin echo spectroscopy around length scales corresponding to the correlation peak q(0). Comparison of samples with different contrasts for neutrons shed light on the two modes dominated either by variation of the oil/water difference or surfactant concentration in the hydrodynamic regime. The results have been compared to theoretical predictions of the relaxation rates of bicontinuous microemulsions by Nonomura and Ohta [M. Nonomura, T. Ohta, J. Chem. Phys. 110, 7516 (1999)]. The influence of modification of the surfactant layer bending constants in the microemulsion by addition of homopolymers (polyethylenepropylene: PEP(X) and polyethyleneoxide: PEO(X), X=5 kg/mol), dissolved in the oil phase and water, has been investigated.
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Affiliation(s)
- O Holderer
- Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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30
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Miyake M, Einaga Y. Characterization of Wormlike Pentaoxyethylene Dodecyl Ether C12E5 Micelles Containing n-Dodecanol. Polym J 2007. [DOI: 10.1295/polymj.pj2006276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Miyake M, Einaga Y. Characteristics of Wormlike Pentaoxyethylene Decyl Ether C10E5 Micelles Containing n-Dodecanol. J Phys Chem B 2006; 111:535-42. [PMID: 17228911 DOI: 10.1021/jp0664465] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The wormlike micelles formed with the surfactant pentaoxyethylene decyl ether C10E5 containing n-dodecanol were characterized by static (SLS) and dynamic light scattering (DLS) experiments. The SLS results have been analyzed with the aid of the light scattering theory for micelle solutions, thereby yielding the molar mass Mw(c) as a function of concentration c along with the cross-sectional diameter d of the micelle. The observed Kc/DeltaR0 as a function of c and the hydrodynamic radius RH as functions of Mw have been well described by the theories for the wormlike spherocylinder model. It has also been demonstrated that the apparent hydrodynamic radius RH,app(c) as a function of c is well described by a fuzzy cylinder theory which takes into account the hydrodynamic and direct collision interactions among micelles. Our previous results for the hexaoxyethylene dodecyl ether C12E6 micelles containing n-dodecanol were reanalyzed in the same scheme. It has been found that the micellar length increases with increasing concentration c or with raising temperature T irrespective of the composition of the C10E5 + n-dodecanol and C12E6 + n-dodecanol systems. The length of the micelles at fixed c and T steeply increases with increasing weight fraction wd of n-dodecanol in both systems. The growth of the micelles accompanies the increase of the cross-sectional diameter d of the micelles and the results that the surfactant molecules are more densely assembled with increasing wd in order to keep n-dodecanol molecules inside the micelles.
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Affiliation(s)
- Maiko Miyake
- Department of Chemistry, Nara Women's University, Nara 630-8506, Japan
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32
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Falus P, Borthwick MA, Narayanan S, Sandy AR, Mochrie SGJ. Crossover from stretched to compressed exponential relaxations in a polymer-based sponge phase. PHYSICAL REVIEW LETTERS 2006; 97:066102. [PMID: 17026180 DOI: 10.1103/physrevlett.97.066102] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Indexed: 05/12/2023]
Abstract
X-ray photon correlation spectroscopy was used to characterize the wave vector- and temperature-dependent dynamics of spontaneous thermal fluctuations in a sponge (L3) phase that occurs in a blend of a symmetric poly(styrene-ethylene/butylene-styrene) triblock copolymer with a polystyrene homopolymer. Measurements of the intermediate scattering function reveal a crossover from stretched- to compressed-exponential relaxations as the temperature is lowered from 180 to 120 degrees C.
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Affiliation(s)
- P Falus
- Department of Physics, Yale University, New Haven, Connecticut 06511, USA
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33
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Pressure-dependence of the bending modulus of surfactant monolayers in ternary microemulsion systems observed by neutron spin echo. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.10.058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Masui T, Imai M, Nakaya K, Taniguchi T. Effects of grafted polymer chains on lamellar membranes. J Chem Phys 2006; 124:74904. [PMID: 16497079 DOI: 10.1063/1.2168452] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have investigated the effects of grafted polymer chains [poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] on the bending modulus and the intermembrane interactions of lamellar membranes (C(12)E(5) water) by means of a neutron spin-echo and a small-angle x-ray scattering technique. In this study the hydrophilic chain takes the mushroom configuration on the membrane. The bending modulus of the polymer-grafted membranes increases in proportion to the square of the end to end distance of the polymer chain, which agrees well with the theoretical prediction of Hiergeist and Lipowsky [J. Phys. II 6, 1465 (1996)]. From the interlamellar interaction point of view, the mushroom layer is renormalized to the membrane thickness, which enhances the repulsive Helfrich interaction. When the size of the decorated polymer chain increases to the interlamellar distance, however, the mushroom is squeezed so as to optimize the interlamellar potential. Further increase of the grafted polymer size brings a lamellar-lamellar phase separation, where the grafted polymer chains are localized in the dilute lamellar phase and the concentrated lamellar phase forms the onionlike texture.
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Affiliation(s)
- Tomomi Masui
- Department of Physics, Faculty of Science, Ochanomizu University, Otsuka, Bunkyo, Tokyo, Japan
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35
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Castro-Roman F, Porcar L, Porte G, Ligoure C. Quantitative analysis of lyotropic lamellar phases SANS patterns in powder oriented samples. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2005; 18:259-72. [PMID: 16231078 DOI: 10.1140/epje/e2005-00029-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Indexed: 05/04/2023]
Abstract
We have developed a detailed numerical method based on the Caillé model to fit Small Angle Neutron Scattering profiles of powder-oriented lyotropic lamellar phases. We thus obtain quantitative values for the Caillé parameter and the smectic penetration length from which we can derive the smectic compression modulus and the membrane mean bending modulus. Our method, applied to a surfactant lamellar phase system decorated by amphiphilic copolymers, provides excellent fits for any intermembrane spacing or membrane concentration over the entire q-range of the SANS experiments. We compare our fits with those obtained from the model of Nallet et al. (J. Phys. II 3, 487 (1993)), which is reviewed. Good fits are obtained with both methods for samples exhibiting "hard" smectic order (sharp Bragg peak, moderate small angle scattering). Only our procedure, however, gives good fits in the case of "soft" smectic order (smooth Bragg peak, strong small angle scattering). A quantitative criterion to discriminate between these "soft" and "hard" samples is also proposed, based on a simple analogy with smectic-A liquid crystal in contact with an undulating solid surface. This allows us to anticipate the type of thermodynamic information that can be derived from the fits.
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Affiliation(s)
- F Castro-Roman
- Laboratoire des Colloïdes, Verres et Nanomatériaux, UMR UM2/CNRS 5587, CC26, Université Montpellier 2, 34095, Monpellier Cedex 05, France
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36
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Porcar L, Hamilton WA, Butler PD, Warr GG. Topological relaxation of a shear-induced lamellar phase to sponge equilibrium and the energetics of membrane fusion. PHYSICAL REVIEW LETTERS 2004; 93:198301. [PMID: 15600891 DOI: 10.1103/physrevlett.93.198301] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Indexed: 05/24/2023]
Abstract
We report time-resolved small angle neutron scattering (t-SANS) measurements of the topological relaxation of Couette shear-induced stacked L(alpha) lamellar states to their multiconnected isotropic L3 sponge equilibrium phases in a surfactant bilayer membrane system. Comparison of this structural relaxation time to the interval between diffusive membrane contacts, as determined from dynamic light scattering or estimated from the shear rates required for L(alpha) saturation, allows us to determine the activation energy barrier to the membrane fusion process reestablishing the solution channel handles that characterize the sponge phase.
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Affiliation(s)
- L Porcar
- National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland 20899, USA
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37
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Imai M, Mawatari R, Nakaya K, Komura S. Inter-lamellar interactions modulated by addition of guest components. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2004; 13:391-400. [PMID: 15170538 DOI: 10.1140/epje/i2003-10085-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have investigated the effects of a guest component (polymer or spherical colloidal particle) confined between flexible lamellar slits on the inter-lamellar interaction by means of a small-angle X-ray scattering technique and a neutron spin echo technique. The dominant interaction between flexible lamellar membranes without guest components is the Helfrich mechanism. The addition of a neutral polymer into the lamellar phase induces an attractive inter-lamellar interaction and finally destabilizes the lamellar phase. On the other hand, spherical colloidal particles confined between flexible lamellar membranes reduce the undulational fluctuations of lamellae and bring a repulsive inter-lamellar interaction. The behavior of the layer compression modulus of the lamellar membrane containing colloidal particles is well described by the entropical repulsive inter-lamellar interaction driven by steric hindrance.
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Affiliation(s)
- M Imai
- Department of Physics, Faculty of Science, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Tokyo 112-0012, Japan.
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39
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Nagao M, Seto H, Takeda T, Kawabata Y. Effects of temperature and pressure on phase transitions in a ternary microemulsion system. J Chem Phys 2001. [DOI: 10.1063/1.1415459] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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