1
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Scott HL, Burns-Casamayor V, Dixson AC, Standaert RF, Stanley CB, Stingaciu LR, Carrillo JMY, Sumpter BG, Katsaras J, Qiang W, Heberle FA, Mertz B, Ashkar R, Barrera FN. Neutron spin echo shows pHLIP is capable of retarding membrane thickness fluctuations. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184349. [PMID: 38815687 PMCID: PMC11365786 DOI: 10.1016/j.bbamem.2024.184349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 04/03/2024] [Accepted: 05/21/2024] [Indexed: 06/01/2024]
Abstract
Cell membranes are responsible for a range of biological processes that require interactions between lipids and proteins. While the effects of lipids on proteins are becoming better understood, our knowledge of how protein conformational changes influence membrane dynamics remains rudimentary. Here, we performed experiments and computer simulations to study the dynamic response of a lipid membrane to changes in the conformational state of pH-low insertion peptide (pHLIP), which transitions from a surface-associated (SA) state at neutral or basic pH to a transmembrane (TM) α-helix under acidic conditions. Our results show that TM-pHLIP significantly slows down membrane thickness fluctuations due to an increase in effective membrane viscosity. Our findings suggest a possible membrane regulatory mechanism, where the TM helix affects lipid chain conformations, and subsequently alters membrane fluctuations and viscosity.
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Affiliation(s)
- Haden L Scott
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville 37996, United States of America
| | - Violeta Burns-Casamayor
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506, United States of America
| | - Andrew C Dixson
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville 37996, United States of America
| | - Robert F Standaert
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville 37996, United States of America; C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506, United States of America; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Christopher B Stanley
- Shull Wollan Center - a Joint Institute for Neutron Sciences, Oak Ridge, TN 37831, United States of America; Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Laura-Roxana Stingaciu
- Labs and Soft Matter Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America; JCNS1, FZJ outstation at SNS, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Jan-Michael Y Carrillo
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America; Center for Nanophase Materials Sciences, Oak Ridge, TN 37831, United States of America
| | - Bobby G Sumpter
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America; Center for Nanophase Materials Sciences, Oak Ridge, TN 37831, United States of America
| | - John Katsaras
- Shull Wollan Center - a Joint Institute for Neutron Sciences, Oak Ridge, TN 37831, United States of America; Labs and Soft Matter Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America; Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, United States of America
| | - Wei Qiang
- Department of Chemistry, the State University of New York, Binghamton, NY 13902, United States of America
| | - Frederick A Heberle
- Department of Chemistry, University of Tennessee, Knoxville, TN 37920, United States of America
| | - Blake Mertz
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506, United States of America; West Virginia University Cancer Institute, Morgantown, WV 26506, United States of America
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA 24061, United States of America; Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, United States of America.
| | - Francisco N Barrera
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville 37996, United States of America.
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2
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Silverstein TP. Oxidative Phosphorylation Does Not Violate the Second Law of Thermodynamics. J Phys Chem B 2024; 128:8448-8458. [PMID: 39167050 PMCID: PMC11382260 DOI: 10.1021/acs.jpcb.4c03047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
In a recent series of papers, James W. Lee reported that mitochondrial oxidative phosphorylation violates the second law of thermodynamics and that it is allowed to do so because it is a "Type-B" process that features lateral and longitudinal membrane asymmetry. We show here that these contentions are based on problematic interpretations of the literature. More reliable values of ΔGredox and ΔGATP synthesis show that the second law is not violated. More recent reports on the structures of the redox-driven proton pumps (Complexes I, III, and IV) suggest that longitudinal membrane asymmetry does not exist. Finally, Lee's predictions for the concentration of protons localized at the P-side surface of the bioenergetic membrane are likely to be much too high due to several errors; thus, his predicted high values of ΔpHsurface that violate the second law are likely to be wrong. There is currently no strong experimental or theoretical evidence to support the contention that oxidative phosphorylation violates the second law of thermodynamics.
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Affiliation(s)
- Todd P Silverstein
- Department of Chemistry (emeritus), Willamette University, Salem, Oregon 97301,United States
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3
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Granek R, Hoffmann I, Kelley EG, Nagao M, Vlahovska PM, Zilman A. Dynamic structure factor of undulating vesicles: finite-size and spherical geometry effects with application to neutron spin echo experiments. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:12. [PMID: 38355850 DOI: 10.1140/epje/s10189-023-00400-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 12/11/2023] [Indexed: 02/16/2024]
Abstract
We consider the dynamic structure factor (DSF) of quasi-spherical vesicles and present a generalization of an expression that was originally formulated by Zilman and Granek (ZG) for scattering from isotropically oriented quasi-flat membrane plaquettes. The expression is obtained in the form of a multi-dimensional integral over the undulating membrane surface. The new expression reduces to the original stretched exponential form in the limit of sufficiently large vesicles, i.e., in the micron range or larger. For much smaller unilamellar vesicles, deviations from the asymptotic, stretched exponential equation are noticeable even if one assumes that the Seifert-Langer leaflet density mode is completely relaxed and membrane viscosity is neglected. To avoid the need for an exhaustive numerical integration while fitting to neutron spin echo (NSE) data, we provide a useful approximation for polydisperse systems that tests well against the numerical integration of the complete expression. To validate the new expression, we performed NSE experiments on variable-size vesicles made of a POPC/POPS lipid mixture and demonstrate an advantage over the original stretched exponential form or other manipulations of the original ZG expression that have been deployed over the years to fit the NSE data. In particular, values of the membrane bending rigidity extracted from the NSE data using the new approximations were insensitive to the vesicle radii and scattering wavenumber and compared very well with expected values of the effective bending modulus ([Formula: see text]) calculated from results in the literature. Moreover, the generalized scattering theory presented here for an undulating quasi-spherical shell can be easily extended to other models for the membrane undulation dynamics beyond the Helfrich Hamiltonian and thereby provides the foundation for the study of the nanoscale dynamics in more complex and biologically relevant model membrane systems.
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Affiliation(s)
- Rony Granek
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel.
| | - Ingo Hoffmann
- Institut Laue-Langevin (ILL), 71 Avenue des Martys, 38042, Grenoble, CEDEX 9, France.
| | - Elizabeth G Kelley
- Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA.
| | - Michihiro Nagao
- Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, 20742, USA
- Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716, USA
| | - Petia M Vlahovska
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL, 60208, USA
| | - Anton Zilman
- Department of Physics, University of Toronto, 60 St George St, Toronto, ON, M5S 1A7, Canada
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4
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Shih KC, Leriche G, Liu CH, He J, John VT, Fang J, Barker JG, Nagao M, Yang L, Yang J, Nieh MP. Antivesiculation and Complete Unbinding of Tail-Tethered Lipids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1688-1697. [PMID: 38186288 DOI: 10.1021/acs.langmuir.3c02663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
We report the effect of tail-tethering on vesiculation and complete unbinding of bilayered membranes. Amphiphilic molecules of a bolalipid, resembling the tail-tethered molecular structure of archaeal lipids, with two identical zwitterionic phosphatidylcholine headgroups self-assemble into a large flat lamellar membrane, in contrast to the multilamellar vesicles (MLVs) observed in its counterpart, monopolar nontethered zwitterionic lipids. The antivesiculation is confirmed by small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cyro-TEM). With the net charge of zero and higher bending rigidity of the membrane (confirmed by neutron spin echo (NSE) spectroscopy), the current membrane theory would predict that membranes should stack with each other (aka "bind") due to dominant van der Waals attraction, while the outcome of the nonstacking ("unbinding") membrane suggests that the theory needs to include entropic contribution for the nonvesicular structures. This report pioneers an understanding of how the tail-tethering of amphiphiles affects the structure, enabling better control over the final nanoscale morphology.
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Affiliation(s)
| | - Geoffray Leriche
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | | | - Jibao He
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Vijay T John
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | | | - John G Barker
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States
| | - Lin Yang
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Jerry Yang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
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5
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Nakao H, Nagao M, Yamada T, Imamura K, Nozaki K, Ikeda K, Nakano M. Impact of transmembrane peptides on individual lipid motions and collective dynamics of lipid bilayers. Colloids Surf B Biointerfaces 2023; 228:113396. [PMID: 37311269 DOI: 10.1016/j.colsurfb.2023.113396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/15/2023] [Accepted: 06/05/2023] [Indexed: 06/15/2023]
Abstract
The fluid nature of lipid bilayers is indispensable for the dynamic regulation of protein function and membrane morphology in biological membranes. Membrane-spanning domains of proteins interact with surrounding lipids and alter the physical properties of lipid bilayers. However, there is no comprehensive view of the effects of transmembrane proteins on the membrane's physical properties. Here, we investigated the effects of transmembrane peptides with different flip-flop-promoting abilities on the dynamics of a lipid bilayer employing complemental fluorescence and neutron scattering techniques. The quasi-elastic neutron scattering and fluorescence experiments revealed that lateral diffusion of the lipid molecules and the acyl chain motions were inhibited by the inclusion of transmembrane peptides. The neutron spin-echo spectroscopy measurements indicated that the lipid bilayer became more rigid but more compressible and the membrane viscosity increased when the transmembrane peptides were incorporated into the membrane. These results suggest that the inclusion of rigid transmembrane structures hinders individual and collective lipid motions by slowing down lipid diffusion and increasing interleaflet coupling. The present study provides a clue for understanding how the local interactions between lipids and proteins change the collective dynamics of the lipid bilayers, and therefore, the function of biological membranes.
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Affiliation(s)
- Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Michihiro Nagao
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899-6102, USA; Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115, USA; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
| | - Takeshi Yamada
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Koki Imamura
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Koichi Nozaki
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Keisuke Ikeda
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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6
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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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7
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Nanoscale Bending Dynamics in Mixed-Chain Lipid Membranes. Symmetry (Basel) 2023. [DOI: 10.3390/sym15010191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Lipids that have two tails of different lengths are found throughout biomembranes in nature, yet the effects of this asymmetry on the membrane properties are not well understood, especially when it comes to the membrane dynamics. Here we study the nanoscale bending fluctuations in model mixed-chain 14:0–18:0 PC (MSPC) and 18:0–14:0 PC (SMPC) lipid bilayers using neutron spin echo (NSE) spectroscopy. We find that despite the partial interdigitation that is known to persist in the fluid phase of these membranes, the collective fluctuations are enhanced on timescales of tens of nanoseconds, and the chain-asymmetric lipid bilayers are softer than an analogous chain-symmetric lipid bilayer with the same average number of carbons in the acyl tails, di-16:0 PC (DPPC). Quantitative comparison of the NSE results suggests that the enhanced bending fluctuations at the nanosecond timescales are consistent with experimental and computational studies that showed the compressibility moduli of chain-asymmetric lipid membranes are 20% to 40% lower than chain-symmetric lipid membranes. These studies add to growing evidence that the partial interdigitation in mixed-chain lipid membranes is highly dynamic in the fluid phase and impacts membrane dynamic processes from the molecular to mesoscopic length scales without significantly changing the bilayer thickness or area per lipid.
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8
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Doole FT, Gupta S, Kumarage T, Ashkar R, Brown MF. Biophysics of Membrane Stiffening by Cholesterol and Phosphatidylinositol 4,5-bisphosphate (PIP2). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:61-85. [PMID: 36988877 DOI: 10.1007/978-3-031-21547-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Cell membranes regulate a wide range of phenomena that are implicated in key cellular functions. Cholesterol, a critical component of eukaryotic cell membranes, is responsible for cellular organization, membrane elasticity, and other critical physicochemical parameters. Besides cholesterol, other lipid components such as phosphatidylinositol 4,5-bisphosphate (PIP2) are found in minor concentrations in cell membranes yet can also play a major regulatory role in various cell functions. In this chapter, we describe how solid-state deuterium nuclear magnetic resonance (2H NMR) spectroscopy together with neutron spin-echo (NSE) spectroscopy can inform synergetic changes to lipid molecular packing due to cholesterol and PIP2 that modulate the bending rigidity of lipid membranes. Fundamental structure-property relations of molecular self-assembly are illuminated and point toward a length and time-scale dependence of cell membrane mechanics, with significant implications for biological activity and membrane lipid-protein interactions.
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Affiliation(s)
- Fathima T Doole
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Sudipta Gupta
- Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, USA
| | - Teshani Kumarage
- Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, USA
| | - Rana Ashkar
- Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, USA.
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA.
- Department of Physics, University of Arizona, Tucson, AZ, USA.
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9
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Heller WT. Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes. Biomolecules 2022; 12:1591. [PMID: 36358941 PMCID: PMC9687511 DOI: 10.3390/biom12111591] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/18/2022] [Accepted: 10/26/2022] [Indexed: 09/23/2023] Open
Abstract
Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.
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Affiliation(s)
- William T Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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10
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Doole FT, Kumarage T, Ashkar R, Brown MF. Cholesterol Stiffening of Lipid Membranes. J Membr Biol 2022; 255:385-405. [PMID: 36219221 PMCID: PMC9552730 DOI: 10.1007/s00232-022-00263-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/05/2022] [Indexed: 11/30/2022]
Abstract
Biomembrane order, dynamics, and other essential physicochemical parameters are controlled by cholesterol, a major component of mammalian cell membranes. Although cholesterol is well known to exhibit a condensing effect on fluid lipid membranes, the extent of stiffening that occurs with different degrees of lipid acyl chain unsaturation remains an enigma. In this review, we show that cholesterol locally increases the bending rigidity of both unsaturated and saturated lipid membranes, suggesting there may be a length-scale dependence of the bending modulus. We review our published data that address the origin of the mechanical effects of cholesterol on unsaturated and polyunsaturated lipid membranes and their role in biomembrane functions. Through a combination of solid-state deuterium NMR spectroscopy and neutron spin-echo spectroscopy, we show that changes in molecular packing cause the universal effects of cholesterol on the membrane bending rigidity. Our findings have broad implications for the role of cholesterol in lipid–protein interactions as well as raft-like mixtures, drug delivery applications, and the effects of antimicrobial peptides on lipid membranes.
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Affiliation(s)
- Fathima T Doole
- Deaprtment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85712, USA
| | - Teshani Kumarage
- Department of Physics, Virginia Tech, Blacksburg, VA, 24061, USA.,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA, 24061, USA. .,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Michael F Brown
- Deaprtment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85712, USA. .,Department of Physics, University of Arizona, Tucson, AZ, 85712, USA.
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11
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Sharma VK, Mamontov E. Multiscale lipid membrane dynamics as revealed by neutron spectroscopy. Prog Lipid Res 2022; 87:101179. [PMID: 35780913 DOI: 10.1016/j.plipres.2022.101179] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 12/22/2022]
Abstract
The plasma membrane is one of the principal structural components of the cell and, therefore, one of the key components of the cellular life. Because the membrane's dynamics links the membrane's structure and function, the complexity and the broad range of the membrane's motions are essential for the enormously diverse functionality of the cell membrane. Even for the main membrane component, the lipid bilayer, considered alone, the range and complexity of the lipid motions are remarkable. Spanning the time scale from sub-picosecond to minutes and hours, the lipid motion in a bilayer is challenging to study even when a broad array of dynamic measurement techniques is employed. Neutron scattering plays a special role among such dynamic measurement techniques, particularly, because it involves the energy transfers commensurate with the typical intra- and inter- molecular dynamics and the momentum transfers commensurate with intra- and inter-molecular distances. Thus, using neutron scattering-based techniques, the spatial and temporal information on the lipid motion can be obtained and analysed simultaneously. Protium vs. deuterium sensitivity and non-destructive character of the neutron probe add to the remarkable prowess of neutron scattering for elucidating the lipid dynamics. Herein we present an overview of the neutron scattering-based studies of lipid dynamics in model membranes, with a discussion of the direct relevance and implications to the real-life cell membranes. The latter are much more complex systems than simple model membranes, consisting of heterogeneous non-stationary domains composed of lipids, proteins, and other small molecules, such as carbohydrates. Yet many fundamental aspects of the membrane behavior and membrane interactions with other molecules can be understood from neutron scattering measurements of the model membranes. For example, such studies can provide a great deal of information on the interactions of antimicrobial compounds with the lipid matrix of a pathogen membrane, or the interactions of drug molecules with the plasma membrane. Finally, we briefly discuss the recently emerging field of neutron scattering membrane studies with a reach far beyond the model membrane systems.
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Affiliation(s)
- V K Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Mumbai 400094, India.
| | - E Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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12
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Gilbert J, Ermilova I, Nagao M, Swenson J, Nylander T. Effect of encapsulated protein on the dynamics of lipid sponge phase: a neutron spin echo and molecular dynamics simulation study. NANOSCALE 2022; 14:6990-7002. [PMID: 35470842 DOI: 10.1039/d2nr00882c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Lipid membranes are highly mobile systems with hierarchical, time and length scale dependent, collective motions including thickness fluctuations, undulations, and topological membrane changes, which play an important role in membrane interactions. In this work we have characterised the effect of encapsulating two industrially important enzymes, β-galactosidase and aspartic protease, in lipid sponge phase nanoparticles on the dynamics of the lipid membrane using neutron spin echo (NSE) spectroscopy and molecular dynamics (MD) simulations. From NSE, reduced membrane dynamics were observed upon enzyme encapsulation, which were dependent on the enzyme concentration and type. By fitting the intermediate scattering functions (ISFs) with a modified Zilman and Granek model including nanoparticle diffusion, an increase in membrane bending rigidity was observed, with a larger effect for β-galactosidase than aspartic protease at the same concentration. MD simulations for the system with and without aspartic protease showed that the lipids relax more slowly in the system with protein due to the replacement of the lipid carbonyl-water hydrogen bonds with lipid-protein hydrogen bonds. This indicates that the most likely cause of the increase in membrane rigidity observed in the NSE measurements was dehydration of the lipid head groups. The dynamics of the protein itself were also studied, which showed a stable secondary structure of protein over the simulation, indicating no unfolding events occurred.
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Affiliation(s)
- Jennifer Gilbert
- Division of Physical Chemistry, Department of Chemistry, Naturvetarvägen 14, Lund University, 22362 Lund, Sweden.
- NanoLund, Lund University, Professorsgatan 1, 223 63 Lund, Sweden
| | - Inna Ermilova
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - Jan Swenson
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Tommy Nylander
- Division of Physical Chemistry, Department of Chemistry, Naturvetarvägen 14, Lund University, 22362 Lund, Sweden.
- NanoLund, Lund University, Professorsgatan 1, 223 63 Lund, Sweden
- Lund Institute of Advanced Neutron and X-Ray Science, Scheelevägen 19, 223 70 Lund, Sweden
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13
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Wood K. Small-Angle Neutron Scattering of Liposomes: Sample Preparation to Simple Modeling. Methods Mol Biol 2022; 2402:143-149. [PMID: 34854042 DOI: 10.1007/978-1-0716-1843-1_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Small-angle scattering (SAS) is a technique commonly used in the soft matter sciences to characterize the structure of molecules self-assembling in solution. As such, it is suitable to study preparations of homogeneous liposomes to extract simple structural parameters such as radius and lipid bilayer thickness in solution. Here, we describe the preparation of liposomes for small-angle neutron scattering via extrusion and present the simplest way the resulting data can be modeled.
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Affiliation(s)
- Kathleen Wood
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee, NSW, Australia.
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14
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Nagao M, Kelley EG, Faraone A, Saito M, Yoda Y, Kurokuzu M, Takata S, Seto M, Butler PD. Relationship between Viscosity and Acyl Tail Dynamics in Lipid Bilayers. PHYSICAL REVIEW LETTERS 2021; 127:078102. [PMID: 34459628 DOI: 10.1103/physrevlett.127.078102] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Membrane viscosity is a fundamental property that controls molecular transport and structural rearrangements in lipid membranes. Given its importance in many cell processes, various experimental and computational methods have been developed to measure the membrane viscosity, yet the estimated values depend highly on the method and vary by orders of magnitude. Here we investigate the molecular origins of membrane viscosity by measuring the nanoscale dynamics of the lipid acyl tails using x-ray and neutron spectroscopy techniques. The results show that the membrane viscosity can be estimated from the structural relaxation times of the lipid tails.
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Affiliation(s)
- Michihiro Nagao
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, Maryland 20899-6102, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115, USA
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - Elizabeth G Kelley
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, Maryland 20899-6102, USA
| | - Antonio Faraone
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, Maryland 20899-6102, USA
| | - Makina Saito
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka, 590-0494, Japan
| | - Yoshitaka Yoda
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo, 679-5198, Japan
| | - Masayuki Kurokuzu
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka, 590-0494, Japan
| | - Shinichi Takata
- J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | - Makoto Seto
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka, 590-0494, Japan
| | - Paul D Butler
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, Maryland 20899-6102, USA
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA
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15
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De Mel JU, Gupta S, Harmon S, Stingaciu L, Roth EW, Siebenbuerger M, Bleuel M, Schneider GJ. Acetaminophen Interactions with Phospholipid Vesicles Induced Changes in Morphology and Lipid Dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9560-9570. [PMID: 34328747 PMCID: PMC8359007 DOI: 10.1021/acs.langmuir.1c01458] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/12/2021] [Indexed: 05/28/2023]
Abstract
Acetaminophen (APAP) or paracetamol, despite its wide and common use for pain and fever symptoms, shows a variety of side effects, toxic effects, and overdose effects. The most common form of toxic effects of APAP is in the liver where phosphatidylcholine is the major component of the cell membrane with additional associated functionalities. Although this is the case, the effects of APAP on pure phospholipid membranes have been largely ignored. Here, we used 1,2-di-(octadecenoyl)-sn-glycero-3-phosphocholine (DOPC), a commonly found phospholipid in mammalian cell membranes, to synthesize large unilamellar vesicles to investigate how the incorporation of APAP changes the pure lipid vesicle structure, morphology, and fluidity at different concentrations. We used a combination of dynamic light scattering, small-angle neutron and X-ray scattering (SANS, SAXS), and cryo-TEM for structural characterization, and neutron spin-echo (NSE) spectroscopy to investigate the dynamics. We showed that the incorporation of APAP in the lipid bilayer significantly impacts the spherical phospholipid self-assembly in terms of its morphology and influences the lipid content in the bilayer, causing a decrease in bending rigidity. We observe a decrease in the number of lipids per vesicle by almost 28% (0.06 wt % APAP) and 19% (0.12 wt % APAP) compared to the pure DOPC (0 wt % APAP). Our results showed that the incorporation of APAP reduces the membrane rigidity by almost 50% and changes the spherical unilamellar vesicles into much more irregularly shaped vesicles. Although the bilayer structure did not show much change when observed by SAXS, NSE and cryo-TEM results showed the lipid dynamics change with the addition of APAP in the bilayer, which causes the overall decreased membrane rigidity. A strong effect on the lipid tail motion showed that the space explored by the lipid tails increases by a factor of 1.45 (for 0.06 wt % APAP) and 1.75 (for 0.12 wt % APAP) compared to DOPC without the drug.
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Affiliation(s)
- Judith U. De Mel
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Sudipta Gupta
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Sydney Harmon
- Department
of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Laura Stingaciu
- Neutron
Sciences Directorate, Oak Ridge National
Laboratory (ORNL), P.O.B 2008, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Eric W. Roth
- Department
of Materials Science and Engineering and NUANCE Center, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
| | - Miriam Siebenbuerger
- Center
of Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, Louisiana 70806, United States
| | - Markus Bleuel
- NIST Center
for Neutron Research, National Institute
of Standards and Technology, Gaithersburg, Maryland 20899-8562, 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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16
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Abstract
Cell membranes - primarily composed of lipids, sterols, and proteins - form a dynamic interface between living cells and their environment. They act as a mechanical barrier around the cell while selectively facilitating material transport, signal transduction, and various other functions necessary for the cell viability. The complex functionality of cell membranes and the hierarchical motions and responses they exhibit demand a thorough understanding of the origin of different membrane dynamics and how they are influenced by molecular additives and environmental cues. These dynamic modes include single-molecule diffusion, thermal fluctuations, and large-scale membrane deformations, to name a few. This review highlights advances in investigating structure-driven dynamics associated with model cell membranes, with a particular focus on insights gained from neutron scattering and spectroscopy experiments. We discuss the uniqueness of neutron contrast variation and its remarkable potential in probing selective membrane structure and dynamics on spatial and temporal scales over which key biological functions occur. We also present a summary of current and future opportunities in synergistic combinations of neutron scattering with molecular dynamics (MD) simulations to gain further understanding of the molecular mechanisms underlying complex membrane functions.
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Affiliation(s)
- Sudipta Gupta
- Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA. and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA. and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA
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17
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Kelley EG, Butler PD, Nagao M. Collective dynamics in lipid membranes containing transmembrane peptides. SOFT MATTER 2021; 17:5671-5681. [PMID: 33942045 PMCID: PMC10466476 DOI: 10.1039/d1sm00314c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Biological membranes are composed of complex mixtures of lipids and proteins that influence each other's structure and function. The biological activities of many channel-forming peptides and proteins are known to depend on the material properties of the surrounding lipid bilayer. However, less is known about how membrane-spanning channels affect the lipid bilayer properties, and in particular, their collective fluctuation dynamics. Here we use neutron spin echo spectroscopy (NSE) to measure the collective bending and thickness fluctuation dynamics in dimyristoylphosphatidylcholine (di 14 : 0 PC, DMPC) lipid membranes containing two different antimicrobial peptides, alamethicin (Ala) and gramicidin (gD). Ala and gD are both well-studied antimicrobial peptides that form oligomeric membrane-spanning channels with different structures. At low concentrations, the peptides did not have a measurable effect on the average bilayer structure, yet significantly changed the collective membrane dynamics. Despite both peptides forming transmembrane channels, they had opposite effects on the relaxation time of the collective bending fluctuations and associated effective bending modulus, where gD addition stiffened the membrane while Ala addition softened the membrane. Meanwhile, the lowest gD concentrations enhanced the collective thickness fluctuation dynamics, while the higher gD concentrations and all studied Ala concentrations dampened these dynamics. The results highlight the synergy between lipids and proteins in determining the collective membrane dynamics and that not all peptides can be universally treated as rigid bodies when considering their effects on the lipid bilayer fluctuations.
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Affiliation(s)
- Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA.
| | - Paul D Butler
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA. and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA and Department of Chemistry, The University of Tennessee Knoxville, TN 37996, USA
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA. and Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
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18
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Kinnun JJ, Scott HL, Ashkar R, Katsaras J. Biomembrane Structure and Material Properties Studied With Neutron Scattering. Front Chem 2021; 9:642851. [PMID: 33987167 PMCID: PMC8110834 DOI: 10.3389/fchem.2021.642851] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/16/2021] [Indexed: 12/12/2022] Open
Abstract
Cell membranes and their associated structures are dynamical supramolecular structures where different physiological processes take place. Detailed knowledge of their static and dynamic structures is therefore needed, to better understand membrane biology. The structure–function relationship is a basic tenet in biology and has been pursued using a range of different experimental approaches. In this review, we will discuss one approach, namely the use of neutron scattering techniques as applied, primarily, to model membrane systems composed of lipid bilayers. An advantage of neutron scattering, compared to other scattering techniques, is the differential sensitivity of neutrons to isotopes of hydrogen and, as a result, the relative ease of altering sample contrast by substituting protium for deuterium. This property makes neutrons an ideal probe for the study of hydrogen-rich materials, such as biomembranes. In this review article, we describe isotopic labeling studies of model and viable membranes, and discuss novel applications of neutron contrast variation in order to gain unique insights into the structure, dynamics, and molecular interactions of biological membranes. We specifically focus on how small-angle neutron scattering data is modeled using different contrast data and molecular dynamics simulations. We also briefly discuss neutron reflectometry and present a few recent advances that have taken place in neutron spin echo spectroscopy studies and the unique membrane mechanical data that can be derived from them, primarily due to new models used to fit the data.
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Affiliation(s)
- Jacob J Kinnun
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Oak Ridge National Laboratory, Shull-Wollan Center, Oak Ridge, TN, United States
| | - Haden L Scott
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Oak Ridge National Laboratory, Shull-Wollan Center, Oak Ridge, TN, United States
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA, United States.,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States
| | - John Katsaras
- Oak Ridge National Laboratory, Shull-Wollan Center, Oak Ridge, TN, United States.,Sample Environment Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, United States
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19
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De Mel JU, Gupta S, Willner L, Allgaier J, Stingaciu LR, Bleuel M, Schneider GJ. Manipulating Phospholipid Vesicles at the Nanoscale: A Transformation from Unilamellar to Multilamellar by an n-Alkyl-poly(ethylene oxide). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2362-2375. [PMID: 33570419 PMCID: PMC8023706 DOI: 10.1021/acs.langmuir.0c03302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/27/2021] [Indexed: 05/05/2023]
Abstract
We investigated the influence of an n-alkyl-PEO polymer on the structure and dynamics of phospholipid vesicles. Multilayer formation and about a 9% increase in the size in vesicles were observed by cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and small-angle neutron/X-ray scattering (SANS/SAXS). The results indicate a change in the lamellar structure of the vesicles by a partial disruption caused by polymer chains, which seems to correlate with about a 30% reduction in bending rigidity per unit bilayer, as revealed by neutron spin echo (NSE) spectroscopy. Also, a strong change in lipid tail relaxation was observed. Our results point to opportunities using synthetic polymers to control the structure and dynamics of membranes, with possible applications in technical materials and also in drug and nutraceutical delivery.
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Affiliation(s)
- Judith U. De Mel
- Department
of Chemistry and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Sudipta Gupta
- Department
of Chemistry and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Lutz Willner
- Jülich
Center for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8) Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Jürgen Allgaier
- Jülich
Center for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8) Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Laura R. Stingaciu
- Neutron
Sciences Directorate, Oak Ridge National
Laboratory (ORNL), 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 20899-8562, United States
| | - Gerald J. Schneider
- Department
of Chemistry and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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20
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Tan L, Elkins JG, Davison BH, Kelley EG, Nickels J. Implementation of a self-consistent slab model of bilayer structure in the SasView suite. J Appl Crystallogr 2021; 54:10.1107/s1600576720015526. [PMID: 37965294 PMCID: PMC10644672 DOI: 10.1107/s1600576720015526] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/23/2020] [Indexed: 11/10/2022] Open
Abstract
Slab models are simple and useful structural descriptions which have long been used to describe lyotropic lamellar phases, such as lipid bilayers. Typically, slab models assume a midline symmetry and break a bilayer structure into three pieces, a central solvent-free core and two symmetric outer layers composed of the soluble portion of the amphiphile and associated solvent. This breakdown matches reasonably well to the distribution of neutron scattering length density and therefore is a convenient and common approach for the treatment of small-angle scattering data. Here, an implementation of this model within the SasView software suite is reported. The implementation is intended to provide physical consistency through the area per amphiphile molecule and number of solvent molecules included within the solvent-exposed outer layer. The proper use of this model requires knowledge of (or good estimates for) the amphiphile and solvent molecule volume and atomic composition, ultimately providing a self-consistent data treatment with only two free parameters: the lateral area per amphiphile molecule and the number of solvent molecules included in the outer region per amphiphile molecule. The use of this code is demonstrated in the fitting of standard lipid bilayer data sets, obtaining structural parameters consistent with prior literature and illustrating the typical and ideal cases of fitting for neutron scattering data obtained using single or multiple contrast conditions. While demonstrated here for lipid bilayers, this model is intended for general application to block copolymers, surfactants, and other lyotropic lamellar phase structures for which a slab model is able to reasonably estimate the neutron scattering length density/electron-density profile of inner and outer layers of the lamellae.
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Affiliation(s)
- Luoxi Tan
- Department of Chemical and Environmental Engineering, University of Cincinnati, 2901 Woodside Drive, Cincinnati, OH 45221, USA
| | - James G. Elkins
- Biosciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Brian H. Davison
- Biosciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Elizabeth G. Kelley
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersberg, MD 20899, USA
| | - Jonathan Nickels
- Department of Chemical and Environmental Engineering, University of Cincinnati, 2901 Woodside Drive, Cincinnati, OH 45221, USA
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21
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Qian S, Sharma VK, Clifton LA. Understanding the Structure and Dynamics of Complex Biomembrane Interactions by Neutron Scattering Techniques. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15189-15211. [PMID: 33300335 DOI: 10.1021/acs.langmuir.0c02516] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The membrane is one of the key structural materials of biology at the cellular level. Composed predominantly of a bilayer of lipids with embedded and bound proteins, it defines the boundaries of the cell and many organelles essential to life and therefore is involved in almost all biological processes. Membrane-specific interactions, such as drug binding to a membrane receptor or the interactions of an antimicrobial compound with the lipid matrix of a pathogen membrane, are of interest across the scientific disciplines. Herein we present a review, aimed at nonexperts, of the major neutron scattering techniques used in membrane studies: small-angle neutron scattering, neutron membrane diffraction, neutron reflectometry, quasielastic neutron scattering, and neutron spin echo. Neutron scattering techniques are well suited to studying biological membranes. The nondestructive nature of cold neutrons means that samples can be measured for long periods without fear of beam damage from ultraviolet, electron, or X-ray radiation, and neutron beams are highly penetrating, thus offering flexibility in samples and sample environments. Most important is the strong difference in neutron scattering lengths between the two most abundant forms of hydrogen, protium and deuterium. Changing the relative amounts of protium/deuterium in a sample allows the production of a series of neutron scattering data sets, enabling the observation of differing components within complex membrane architectures. This approach can be as simple as using the naturally occurring neutron contrast between different biomolecules to study components in a complex by changing the solution H2O/D2O ratio or as complex as selectively labeling individual components with hydrogen isotopes. This review presents an overview of each experimental technique with the neutron instrument configuration, related sample preparation and sample environment, and data analysis, highlighted by a special emphasis on using prominent neutron contrast to understand structure and dynamics. This review gives researchers a practical introduction to the often enigmatic suite of neutron beamlines, thereby lowering the barrier to taking advantage of these large-facility techniques to achieve new understandings of membranes and their interactions with other molecules.
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Affiliation(s)
- Shuo Qian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Veerendra Kumar Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Luke A Clifton
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, U.K. OX11 0QX
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22
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Sharma VK, Ghosh SK, García Sakai V, Mukhopadhyay R. Enhanced Microscopic Dynamics of a Liver Lipid Membrane in the Presence of an Ionic Liquid. Front Chem 2020; 8:577508. [PMID: 33330366 PMCID: PMC7710540 DOI: 10.3389/fchem.2020.577508] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/01/2020] [Indexed: 12/19/2022] Open
Abstract
Ionic liquids (ILs) are an important class of emerging compounds, owing to their widespread industrial applications in high-performance lubricants for food and cellulose processing, despite their toxicity to living organisms. It is believed that this toxicity is related to their actions on the cellular membrane. Hence, it is vital to understand the interaction of ILs with cell membranes. Here, we report on the effects of an imidazolium-based IL, 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM[BF4]), on the microscopic dynamics of a membrane formed by liver extract lipid, using quasielastic neutron scattering (QENS). The presence of significant quasielastic broadening indicates that stochastic molecular motions of the lipids are active in the system. Two distinct molecular motions, (i) lateral motion of the lipid within the membrane leaflet and (ii) localized internal motions of the lipid, are found to contribute to the QENS broadening. While the lateral motion could be described assuming continuous diffusion, the internal motion is explained on the basis of localized translational diffusion. Incorporation of the IL into the liver lipid membrane is found to enhance the membrane dynamics by accelerating both lateral and internal motions of the lipids. This indicates that the IL induces disorder in the membrane and enhances the fluidity of lipids. This could be explained on the basis of its location in the lipid membrane. Results are compared with various other additives and we provide an indication of a possible correlation between the effects of guest molecules on the dynamics of the membrane and its location within the membrane.
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Affiliation(s)
- Veerendra K Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, India.,Homi Bhabha National Institute, Mumbai, India
| | - Sajal K Ghosh
- Department of Physics, School of Natural Sciences, Shiv Nadar University, Greater Noida, India
| | - Victoria García Sakai
- Rutherford Appleton Laboratory, ISIS Pulsed Neutron and Muon Facility, Science and Technology Facilities Council, Didcot, United Kingdom
| | - R Mukhopadhyay
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, India.,Homi Bhabha National Institute, Mumbai, India
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23
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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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24
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Membrane stiffness and myelin basic protein binding strength as molecular origin of multiple sclerosis. Sci Rep 2020; 10:16691. [PMID: 33028889 PMCID: PMC7542173 DOI: 10.1038/s41598-020-73671-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/21/2020] [Indexed: 01/08/2023] Open
Abstract
Myelin basic protein (MBP) and its interaction with lipids of the myelin sheath plays an important part in the pathology of multiple sclerosis (MS). Previous studies observed that changes in the myelin lipid composition lead to instabilities and enhanced local curvature of MBP-lipid multilayer structures. We investigated the molecular origin of the instability and found that the diseased lipid membrane has a 25% lower bending rigidity, thus destabilizing smooth \documentclass[12pt]{minimal}
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\begin{document}$$>1\,$$\end{document}>1µm curvature radius structures such as in giant unilamellar vesicles. MBP-mediated assembling of lipid bilayers proceeds in two steps, with a slow second step occurring over many days where native lipid membranes assemble into well-defined multilayer structures, whereas diseased lipid membranes form folded assemblies with high local curvature. For both native and diseased lipid mixtures we find that MBP forms dense liquid phases on top of the lipid membranes mediating attractive membrane interactions. Furthermore, we observe MBP to insert into its bilayer leaflet side in case of the diseased lipid mixture, whereas there is no insertion for the native mixture. Insertion increases the local membrane curvature, and could be caused by a decrease of the sphingomyelin content of the diseased lipid mixture. These findings can help to open a pathway to remyelination strategies.
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25
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Kelley EG, Butler PD, Ashkar R, Bradbury R, Nagao M. Scaling relationships for the elastic moduli and viscosity of mixed lipid membranes. Proc Natl Acad Sci U S A 2020; 117:23365-23373. [PMID: 32883879 PMCID: PMC7519290 DOI: 10.1073/pnas.2008789117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The elastic and viscous properties of biological membranes play a vital role in controlling cell functions that require local reorganization of the membrane components as well as dramatic shape changes such as endocytosis, vesicular trafficking, and cell division. These properties are widely acknowledged to depend on the unique composition of lipids within the membrane, yet the effects of lipid mixing on the membrane biophysical properties remain poorly understood. Here, we present a comprehensive characterization of the structural, elastic, and viscous properties of fluid membranes composed of binary mixtures of lipids with different tail lengths. We show that the mixed lipid membrane properties are not simply additive quantities of the single-component analogs. Instead, the mixed membranes are more dynamic than either of their constituents, quantified as a decrease in their bending modulus, area compressibility modulus, and viscosity. While the enhanced dynamics are seemingly unexpected, we show that the measured moduli and viscosity for both the mixed and single-component bilayers all scale with the area per lipid and collapse onto respective master curves. This scaling links the increase in dynamics to mixing-induced changes in the lipid packing and membrane structure. More importantly, the results show that the membrane properties can be manipulated through lipid composition the same way bimodal blends of surfactants, liquid crystals, and polymers are used to engineer the mechanical properties of soft materials, with broad implications for understanding how lipid diversity relates to biomembrane function.
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Affiliation(s)
- Elizabeth G Kelley
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899;
| | - Paul D Butler
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716
- Department of Chemistry, The University of Tennessee, Knoxville, TN 37996
| | - Rana Ashkar
- Physics Department, Virginia Tech, Blacksburg, VA 20461
- Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 20461
| | - Robert Bradbury
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408
| | - Michihiro Nagao
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716
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26
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DiPasquale M, Gbadamosi O, Nguyen MHL, Castillo SR, Rickeard BW, Kelley EG, Nagao M, Marquardt D. A Mechanical Mechanism for Vitamin E Acetate in E-cigarette/Vaping-Associated Lung Injury. Chem Res Toxicol 2020; 33:2432-2440. [PMID: 32842741 DOI: 10.1021/acs.chemrestox.0c00212] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The outbreak of electronic-cigarette/vaping-associated lung injury (EVALI) has made thousands ill. This lung injury has been attributed to a physical interaction between toxicants from the vaping solution and the pulmonary surfactant. In particular, studies have implicated vitamin E acetate as a potential instigator of EVALI. Pulmonary surfactant is vital to proper respiration through the mechanical processes of adsorption and interface stability to achieve and maintain low surface tension at the air-liquid interface. Using neutron spin echo spectroscopy, we investigate the impact of vitamin E acetate on the mechanical properties of two lipid-only pulmonary surfactant mimics: pure 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and a more comprehensive lipid mixture. It was found that increasing vitamin E acetate concentration nonlinearly increased membrane fluidity and area compressibility to a plateau. Softer membranes would promote adsorption to the air-liquid interface during inspiration as well as collapse from the interface during expiration. These findings indicate the potential for the failure of the pulmonary surfactant upon expiration, attributed to monolayer collapse. This collapse could contribute to the observed EVALI signs and symptoms, including shortness of breath and pneumonitis.
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Affiliation(s)
| | | | | | | | | | - Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.,Center for Exploration of Energy and Matter, Department of Physics, Indiana University, Bloomington, Indiana 47408, United States.,Department of Physics and AstronomyUniversity of DelawareNewarkDelaware19716United States
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Kelley EG, Nagao M, Butler PD, Porcar L, Farago B. Enhanced dynamics in the anomalous melting regime of DMPG lipid membranes. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:054704. [PMID: 33094128 PMCID: PMC7568673 DOI: 10.1063/4.0000031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/25/2020] [Indexed: 06/11/2023]
Abstract
Like many soft materials, lipids undergo a melting transition associated with a significant increase in their dynamics. At temperatures below the main melting transition (Tm ), all molecular and collective dynamics are suppressed, while above Tm the alkyl tail motions, lipid diffusivity, and collective membrane undulations are at least an order of magnitude faster. Here we study the collective dynamics of dimyristoylphosphatidylglycerol (DMPG, di 14:0 PG) using neutron spin echo spectroscopy throughout its anomalous phase transition that occurs over a 12 °C-20° C wide temperature window. Our results reveal that the membranes are softer and more dynamic during the phase transition than at higher temperatures corresponding to the fluid phase and provide direct experimental evidence for the predicted increase in membrane fluctuations during lipid melting. These results provide new insights into the nanoscale lipid membrane dynamics during the melting transition and demonstrate how these dynamics are coupled to changes in the membrane structure.
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Affiliation(s)
- Elizabeth G. Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20889, USA
| | | | | | - Lionel Porcar
- Institut Laue-Langevin (ILL), Grenoble F-38042, France
| | - Bela Farago
- Institut Laue-Langevin (ILL), Grenoble F-38042, France
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Sharma VK, Srinivasan H, García Sakai V, Mitra S. Dioctadecyldimethylammonium bromide, a surfactant model for the cell membrane: Importance of microscopic dynamics. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:051301. [PMID: 32984433 PMCID: PMC7511241 DOI: 10.1063/4.0000030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/25/2020] [Indexed: 05/11/2023]
Abstract
Cationic lipid membranes have recently attracted huge attention both from a fundamental point of view and due to their practical applications in drug delivery and gene therapy. The dynamical behavior of the lipids in the membrane is a key parameter controlling various physiological processes and drug release kinetics. Here, we review the dynamical and thermotropic phase behavior of an archetypal cationic lipid membrane, dioctadecyldimethylammonium bromide (DODAB), as studied using neutron scattering and molecular dynamics simulation techniques. DODAB membranes exhibit interesting phase behavior, specifically showing coagel, gel, and fluid phases in addition to a large hysteresis when comparing heating and cooling cycles. The dynamics of the lipid membrane is strongly dependent on the physical state of the bilayer. Lateral diffusion of the lipids is faster, by an order of magnitude, in the fluid phase than in the ordered phase. It is not only the characteristic times but also the nature of the segmental motions that differ between the ordered and fluid phases. The effect of different membrane active molecules including drugs, stimulants, gemini surfactants, and unsaturated lipids, on the dynamical and thermotropic phase behavior of the DODAB membrane, is also discussed here. Various interesting features such as induced synchronous ordering between polar head groups and tails, sub diffusive behavior, etc., are observed. The results shed light on the interaction between these additives and the membrane, which is found to be a complex interplay between the physical state of the membrane, charge, concentration, molecular architecture of the additives, and their location within the membrane.
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Affiliation(s)
- V. K. Sharma
- Author to whom correspondence should be addressed: and . Phone: +91-22-25594604
| | | | - V. García Sakai
- ISIS Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
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Abstract
Cholesterol is an integral component of eukaryotic cell membranes and a key molecule in controlling membrane fluidity, organization, and other physicochemical parameters. It also plays a regulatory function in antibiotic drug resistance and the immune response of cells against viruses, by stabilizing the membrane against structural damage. While it is well understood that, structurally, cholesterol exhibits a densification effect on fluid lipid membranes, its effects on membrane bending rigidity are assumed to be nonuniversal; i.e., cholesterol stiffens saturated lipid membranes, but has no stiffening effect on membranes populated by unsaturated lipids, such as 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). This observation presents a clear challenge to structure-property relationships and to our understanding of cholesterol-mediated biological functions. Here, using a comprehensive approach-combining neutron spin-echo (NSE) spectroscopy, solid-state deuterium NMR (2H NMR) spectroscopy, and molecular dynamics (MD) simulations-we report that cholesterol locally increases the bending rigidity of DOPC membranes, similar to saturated membranes, by increasing the bilayer's packing density. All three techniques, inherently sensitive to mesoscale bending fluctuations, show up to a threefold increase in effective bending rigidity with increasing cholesterol content approaching a mole fraction of 50%. Our observations are in good agreement with the known effects of cholesterol on the area-compressibility modulus and membrane structure, reaffirming membrane structure-property relationships. The current findings point to a scale-dependent manifestation of membrane properties, highlighting the need to reassess cholesterol's role in controlling membrane bending rigidity over mesoscopic length and time scales of important biological functions, such as viral budding and lipid-protein interactions.
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De Mel JU, Gupta S, Perera RM, Ngo L, Zolnierczuk P, Bleuel M, Pingali SV, Schneider GJ. Influence of External NaCl Salt on Membrane Rigidity of Neutral DOPC Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9356-9367. [PMID: 32672981 DOI: 10.1021/acs.langmuir.0c01004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Sodium chloride (NaCl) is a very common molecule in biotic and abiotic aqueous environments. In both cases, variation of ionic strength is inevitable. In addition to the osmotic variation posed by such perturbations, the question of whether the interactions of monovalent ions Na+ and Cl-, especially with the neutral head groups of phospholipid membranes are impactful enough to change the membrane rigidity, is still not entirely understood. We investigated the dynamics of 1,2-di-(octadecenoyl)-sn-glycero-3-phosphocholine (DOPC) vesicles with zwitterionic neutral head groups in the fluid phase with increasing external salt concentration. At higher salt concentrations, we observe an increase in bending rigidity from neutron spin echo (NSE) spectroscopy and an increase in bilayer thickness from small-angle X-ray scattering (SAXS). We compared different models to distinguish membrane undulations, lipid tail motions, and the translational diffusion of the vesicles. All of the models indicate an increase in bending rigidity by a factor of 1.3-3.6. We demonstrate that even down to t > 10 ns and for Q > 0.07 Å-1, the observed NSE relaxation spectra are influenced by translational diffusion of the vesicles. For t < 5 ns, the lipid tail motion dominates the intermediate dynamic structure factor. As the salt concentration increases, this contribution diminishes. We introduced a time-dependent analysis for the bending rigidity that highlights only a limited Zilman-Granek time window in which the rigidity is physically meaningful.
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Affiliation(s)
- Judith U De Mel
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Sudipta Gupta
- 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
| | - Ly Ngo
- 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 20899-8562, United States
| | - Sai Venkatesh Pingali
- Neutron Sciences Directorate, Oak Ridge National Laboratory (ORNL), POB 2008, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, 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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Gupta S, Schneider GJ. Modeling the dynamics of phospholipids in the fluid phase of liposomes. SOFT MATTER 2020; 16:3245-3256. [PMID: 32163059 DOI: 10.1039/c9sm02111f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We present the derivation of a new model to describe neutron spin echo spectroscopy and quasi-elastic neutron scattering data on liposomes. We compare the new model with existing approaches and benchmark it with experimental data. The analysis indicates the importance of including all major contributions in the modeling of the intermediate scattering function. Simultaneous analysis of the experimental data on lipids with full contrast and tail contrast matched samples reveals highly confined lipid tail motion. A comparison of their dynamics demonstrates the statistical independence of tail-motion and height-height correlation of the membrane. A more detailed analysis indicates that the lipid tail relaxation is confined to a potential with cylindrical symmetry, in addition to the undulation and diffusive motion of the liposome. Despite substantial differences in the chemistry of the fatty acid tails, the observation indicates a universal behavior. The analysis of partially deuterated systems confirms the strong contribution of the lipid tail to the intermediate scattering function. Within the time range from 5 to 100 ns, the intermediate scattering function can be described by the height-height correlation function. The existence of the fast-localized tail motion and the contribution of slow translational diffusion of liposomes determine the intermediate scattering function for t < 5 ns and t > 100 ns, respectively. Taking into account the limited time window lowers the bending moduli by a factor of 1.3 (DOPC) to 2 (DMPC) compared to the full range.
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Affiliation(s)
- Sudipta Gupta
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Gerald J Schneider
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA. and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
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On the Origin of the Anomalous Behavior of Lipid Membrane Properties in the Vicinity of the Chain-Melting Phase Transition. Sci Rep 2020; 10:5749. [PMID: 32238845 PMCID: PMC7113312 DOI: 10.1038/s41598-020-62577-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/28/2020] [Indexed: 11/08/2022] Open
Abstract
Biomembranes are key objects of numerous studies in biology and biophysics of great importance to medicine. A few nanometers thin quasi two-dimensional liquid crystalline membranes with bending rigidity of a few kT exhibit unusual properties and they are the focus of theoretical and experimental physics. The first order chain-melting phase transition of lipid membranes is observed to be accompanied by a pseudocritical behavior of membrane physical-chemical properties. However, the investigation of the nature of the anomalous swelling of a stack of lipid membranes in the vicinity of the transition by different groups led to conflicting conclusions about the level of critical density fluctuations and their impact on the membrane softening. Correspondingly, conclusions about the contribution of Helfrich's undulations to the effect of swelling were different. In our work we present a comprehensive complementary neutron small-angle and spin-echo study directly showing the presence of significant critical fluctuations in the vicinity of the transition which induce membrane softening. However, contrary to the existing paradigm, we demonstrate that the increased undulation forces cannot explain the anomalous swelling. We suggest that the observed effect is instead determined by the dominating increase of short-range entropic repulsion.
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Yu J, Mao J, Nagao M, Bu W, Lin B, Hong K, Jiang Z, Liu Y, Qian S, Tirrell M, Chen W. Structure and dynamics of lipid membranes interacting with antivirulence end-phosphorylated polyethylene glycol block copolymers. SOFT MATTER 2020; 16:983-989. [PMID: 31851201 DOI: 10.1039/c9sm01642b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The structure and dynamics of lipid membranes in the presence of extracellular macromolecules are critical for cell membrane functions and many pharmaceutical applications. The pathogen virulence-suppressing end-phosphorylated polyethylene glycol (PEG) triblock copolymer (Pi-ABAPEG) markedly changes the interactions with lipid vesicle membranes and prevents PEG-induced vesicle phase separation in contrast to the unphosphorylated copolymer (ABAPEG). Pi-ABAPEG weakly absorbs on the surface of lipid vesicle membranes and slightly changes the structure of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) unilamellar vesicles at 37 °C, as evidenced by small angle neutron scattering. X-ray reflectivity measurements confirm the weak adsorption of Pi-ABAPEG on DMPC monolayer, resulting in a more compact DMPC monolayer structure. Neutron spin-echo results show that the adsorption of Pi-ABAPEG on DMPC vesicle membranes increases the membrane bending modulus κ.
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Affiliation(s)
- Jing Yu
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Jun Mao
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Michihiro Nagao
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA and Centre for Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408, USA
| | - Wei Bu
- Centre for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, USA
| | - Binhua Lin
- Centre for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, USA and James Franck Institute, University of Chicago, Chicago, IL 60637, USA
| | - Kunlun Hong
- Centre for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zhang Jiang
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Yun Liu
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA and Department of Chemical and Biomolecular Engineering, Centre for Neutron Science, University of Delaware, Newark, DE 19716, USA
| | - Shuo Qian
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Matthew Tirrell
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Wei Chen
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
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Rickeard BW, Nguyen MHL, DiPasquale M, Yip CG, Baker H, Heberle FA, Zuo X, Kelley EG, Nagao M, Marquardt D. Transverse lipid organization dictates bending fluctuations in model plasma membranes. NANOSCALE 2020; 12:1438-1447. [PMID: 31746906 DOI: 10.1039/c9nr07977g] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Membrane undulations play a vital role in many biological processes, including the regulation of membrane protein activity. The asymmetric lipid composition of most biological membranes complicates theoretical description of these bending fluctuations, yet experimental data that would inform any such a theory is scarce. Here, we used neutron spin-echo (NSE) spectroscopy to measure the bending fluctuations of large unilamellar vesicles (LUV) having an asymmetric transbilayer distribution of high- and low-melting lipids. The asymmetric vesicles were prepared using cyclodextrin-mediated lipid exchange, and were composed of an outer leaflet enriched in egg sphingomyelin (ESM) and an inner leaflet enriched in 1-palmitoyl-2-oleoyl-phosphoethanolamine (POPE), which have main transition temperatures of 37 °C and 25 °C, respectively. The overall membrane bending rigidity was measured at three temperatures: 15 °C, where both lipids are in a gel state; 45 °C, where both lipids are in a fluid state; and 30 °C, where there is gel-fluid co-existence. Remarkably, the dynamics for the fluid asymmetric LUVs (aLUVs) at 30 °C and 45 °C do not follow trends predicted by their symmetric counterparts. At 30 °C, compositional asymmetry suppressed the bending fluctuations, with the asymmetric bilayer exhibiting a larger bending modulus than that of symmetric bilayers corresponding to either the outer or inner leaflet. We conclude that the compositional asymmetry and leaflet coupling influence the internal dissipation within the bilayer and result in membrane properties that cannot be directly predicted from corresponding symmetric bilayers.
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Affiliation(s)
- Brett W Rickeard
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada.
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Usuda H, Hishida M, Kelley EG, Yamamura Y, Nagao M, Saito K. Interleaflet coupling of n-alkane incorporated bilayers. Phys Chem Chem Phys 2020; 22:5418-5426. [PMID: 31904060 DOI: 10.1039/c9cp06059f] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The relationship between the membrane bending modulus (κ) and compressibility modulus (KA) depends on the extent of coupling between the two monolayers (leaflets). Using neutron spin echo (NSE) spectroscopy, we investigate the effects of n-alkanes on the interleaflet coupling of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers. Structural studies with small-angle X-ray and neutron scattering (SAXS and SANS) showed that the bilayer thickness increased with increasing n-alkane length, while NSE suggested that the bilayers became softer. Additional measurements of the membrane thickness fluctuations with NSE suggested that the changes in elastic moduli were due to a decrease in coupling between the leaflets upon addition of the longer n-alkanes. The decreased coupling with elongating n-alkane length was explained based on the n-alkane distribution within the bilayers characterized by SANS measurement of bilayers composed of protiated DPPC and deuterated n-alkanes. A higher fraction of the incorporated long n-alkanes were concentrated at the central plane of the bilayers and decreased the physical interaction between the leaflets. Using NSE and SANS, we successfully correlated changes in the mesoscopic collective dynamics and microscopic membrane structure upon incorporation of n-alkanes.
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Affiliation(s)
- Hatsuho Usuda
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
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Sharma VK, Nagao M, Rai DK, Mamontov E. Membrane softening by nonsteroidal anti-inflammatory drugs investigated by neutron spin echo. Phys Chem Chem Phys 2019; 21:20211-20218. [PMID: 31486459 DOI: 10.1039/c9cp03767e] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In spite of their well-known side effects, the nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most commonly prescribed medications for their antipyretic and anti-inflammatory actions. Interaction of NSAIDs with the plasma membrane plays a vital role in their therapeutic actions and defines many of their side effects. In the present study, we investigate the effects of three NSAIDs, aspirin, ibuprofen, and indomethacin, on the structure and dynamics of a model plasma membrane using a combination of small angle neutron scattering (SANS) and neutron spin echo (NSE) techniques. The SANS and NSE measurements were carried out on a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membrane, with and without NSAIDs, at two different temperatures, 11 °C and 37 °C, where the DMPC membrane is in the gel and fluid phase, respectively. SANS data analysis shows that incorporation of NSAIDs leads to bilayer thinning of the membrane in both the phases. The dynamic properties of the membrane are represented by the intermediate scattering functions for NSE data, which are successfully described by the Zilman and Granek model. NSE data analysis shows that in both gel and fluid phases, addition of NSAIDs results in a decrease in the bending rigidity and compressibility modulus of the membrane, which is more prominent when the membrane is in the gel phase. The magnitude of the effect of NSAIDs on the bending rigidity and compressibility modulus of the membrane in the gel phase follows an order of ibuprofen > aspirin > indomethacin, whereas in the fluid phase, it is in the order of aspirin > ibuprofen > indomethacin. We find that the interaction between NSAIDs and phospholipid membranes is strongly dependent on the chemical structure of the drugs and physical state of the membrane. Mechanical properties of the membrane can be quantified by the membrane's bending rigidity. Hence, the present study reveals that incorporation of NSAIDs modulates the mechanical properties of the membrane, which may affect several physiological processes, particularly those linked to the membrane curvature.
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Affiliation(s)
- V K Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
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Ghosh S, Mohajerani F, Son S, Velegol D, Butler PJ, Sen A. Motility of Enzyme-Powered Vesicles. NANO LETTERS 2019; 19:6019-6026. [PMID: 31429577 DOI: 10.1021/acs.nanolett.9b01830] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Autonomous nanovehicles powered by energy derived from chemical catalysis have potential applications as active delivery agents. For in vivo applications, it is necessary that the engine and its fuel, as well as the chassis itself, be biocompatible. Enzyme molecules have been shown to display enhanced motility through substrate turnover and are attractive candidates as engines; phospholipid vesicles are biocompatible and can serve as cargo containers. Herein, we describe the autonomous movement of vesicles with membrane-bound enzymes in the presence of the substrate. We find that the motility of the vesicles increases with increasing enzymatic turnover rate. The enhanced diffusion of these enzyme-powered systems was further substantiated in real time by tracking the motion of the vesicles using optical microscopy. The membrane-bound protocells that move by transducing chemical energy into mechanical motion serve as models for motile living cells and are key to the elucidation of the fundamental mechanisms governing active membrane dynamics and cellular movement.
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Dolstra CC, Rinker T, Sankhagowit S, Deng S, Ting C, Dang AT, Kuhl TL, Sasaki DY. Mechanism of Acid-Triggered Cargo Release from Lipid Bilayer-Coated Mesoporous Silica Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10276-10285. [PMID: 31280569 DOI: 10.1021/acs.langmuir.9b01087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lipid bilayer-coated mesoporous silica nanoparticles are unique core-shell nanomaterials currently being developed as drug delivery vehicles. To improve cargo loading and biocirculation, the pore structure and surface chemistry of the particle have been modified and well characterized. However, an understanding of cargo release mechanisms from cellular uptake pathways remains largely unexplored. Here, we present a study of the release mechanism of lipid bilayer-coated silica particles induced by endosomal-like pH change from 7.4 to 5.0. We found that this relatively small pH change produces rapid deformation of the supported lipid bilayer that ultimately results in holes in the membrane. Using a combination of dye release studies, wide-field and confocal fluorescence microscopies, and surface area modeling analysis, we determined that small blister-like structures are formed, which lead to lateral membrane displacement and hole formation. Possible mechanisms for the blister formation, which include curvature effects and interfacial interactions, are discussed.
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Affiliation(s)
- Cassidy C Dolstra
- Biotechnology and Bioengineering Department , Sandia National Laboratories , Livermore 94550 , California , United States
| | - Torri Rinker
- Biotechnology and Bioengineering Department , Sandia National Laboratories , Livermore 94550 , California , United States
| | - Shalene Sankhagowit
- Biotechnology and Bioengineering Department , Sandia National Laboratories , Livermore 94550 , California , United States
| | - Sarah Deng
- Biotechnology and Bioengineering Department , Sandia National Laboratories , Livermore 94550 , California , United States
| | - Christina Ting
- Nanosystems Synthesis/Analysis Department , Sandia National Laboratories , Albuquerque 87185 , New Mexico , United States
| | - Amanda T Dang
- Chemical Engineering Department , University of California, Davis , Davis , California 95616 , United States
| | - Tonya L Kuhl
- Chemical Engineering Department , University of California, Davis , Davis , California 95616 , United States
| | - Darryl Y Sasaki
- Biotechnology and Bioengineering Department , Sandia National Laboratories , Livermore 94550 , California , United States
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40
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Kirsch SA, Böckmann RA. Coupling of Membrane Nanodomain Formation and Enhanced Electroporation near Phase Transition. Biophys J 2019; 116:2131-2148. [PMID: 31103234 PMCID: PMC6554532 DOI: 10.1016/j.bpj.2019.04.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 04/17/2019] [Accepted: 04/18/2019] [Indexed: 12/29/2022] Open
Abstract
Biological cells are enveloped by a heterogeneous lipid bilayer that prevents the uncontrolled exchange of substances between the cell interior and its environment. In particular, membranes act as a continuous barrier for salt and macromolecules to ensure proper physiological functions within the cell. However, it has been shown that membrane permeability strongly depends on temperature and, for phospholipid bilayers, displays a maximum at the transition between the gel and fluid phase. Here, extensive molecular dynamics simulations of dipalmitoylphosphatidylcholine bilayers were employed to characterize the membrane structure and dynamics close to phase transition, as well as its stability with respect to an external electric field. Atomistic simulations revealed the dynamic appearance and disappearance of spatially related nanometer-sized thick ordered and thin interdigitating domains in a fluid-like bilayer close to the phase transition temperature (Tm). These structures likely represent metastable precursors of the ripple phase that vanished at increased temperatures. Similarly, a two-phase bilayer with coexisting gel and fluid domains featured a thickness minimum at the interface because of splaying and interdigitating lipids. For all systems, application of an external electric field revealed a reduced bilayer stability with respect to pore formation for temperatures close to Tm. Pore formation occurred exclusively in thin interdigitating membrane nanodomains. These findings provide a link between the increased membrane permeability and the structural heterogeneity close to phase transition.
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Affiliation(s)
- Sonja A Kirsch
- Computational Biology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - Rainer A Böckmann
- Computational Biology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany.
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41
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Granek R. Comment on “Dynamics of Phospholipid Membranes beyond Thermal Undulations”. J Phys Chem B 2019; 123:5665-5666. [DOI: 10.1021/acs.jpcb.9b03049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rony Granek
- The Stella and Avram Goren-Goldstein Department of Biotechnology Engineering and the Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University of The Negev, Beer Sheva 84105, Israel
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Gupta S, De Mel JU, Schneider GJ. Reply to “Comment on ‘Dynamics of Phospholipid Membranes beyond Thermal Undulation’”. J Phys Chem B 2019; 123:5667-5669. [DOI: 10.1021/acs.jpcb.9b04739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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
| | - 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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Kelley EG, Butler PD, Nagao M. Scaling of lipid membrane rigidity with domain area fraction. SOFT MATTER 2019; 15:2762-2767. [PMID: 30789180 PMCID: PMC8220873 DOI: 10.1039/c8sm02362j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Biological membranes are highly heterogeneous in composition which in turn leads to local variations in the physical properties. Here we quantify how heterogeneity in stiffness determines the effective bending modulus, κeff, of model phase-separated membranes with coexisting soft fluid and rigid gel domains. We find that the temperature- and composition- dependent trends in membrane rigidity collapse onto a single curve, such that κeff directly scales with the area fraction of the rigid gel domains. Using no adjustable parameters, the measurements are found to agree with theoretical predictions for inhomogenous membranes and indicate that κeff is sensitive to the lateral distribution of the rigid phase within the membrane. This key finding confirms that the properties of heterogeneous membranes can be quantitatively predicted if the area fraction and properties of the individual phases are known.
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Affiliation(s)
- Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, USA.
| | - Paul D Butler
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, USA. and Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, DE, USA and Department of Chemistry, The University of Tennessee, Knoxville, TN 37996, USA
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, USA. and Center for Exploration of Energy and Matter, Indiana University, 2401 N. Milo B. Sampson Lane, Bloomington, IN, USA.
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Influence of Chemically Disrupted Photosynthesis on Cyanobacterial Thylakoid Dynamics in Synechocystis sp. PCC 6803. Sci Rep 2019; 9:5711. [PMID: 30952892 PMCID: PMC6450941 DOI: 10.1038/s41598-019-42024-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 03/18/2019] [Indexed: 12/22/2022] Open
Abstract
The photosynthetic machinery of the cyanobacterium Synechocystis sp. PCC 6803 resides in flattened membrane sheets called thylakoids, situated in the peripheral part of the cellular cytoplasm. Under photosynthetic conditions these thylakoid membranes undergo various dynamical processes that could be coupled to their energetic functions. Using Neutron Spin Echo Spectroscopy (NSE), we have investigated the undulation dynamics of Synechocystis sp. PCC 6803 thylakoids under normal photosynthetic conditions and under chemical treatment with DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea), an herbicide that disrupts photosynthetic electron transfer. Our measurements show that DCMU treatment has a similar effect as dark conditions, with differences in the undulation modes of the untreated cells compared to the chemically inhibited cells. We found that the disrupted membranes are 1.5-fold more rigid than the native membranes during the dark cycle, while in light they relax approximately 1.7-fold faster than native and they are 1.87-fold more flexible. The strength of the herbicide disruption effect is characterized further by the damping frequency of the relaxation mode and the decay rate of the local shape fluctuations. In the dark, local thicknesses and shape fluctuations relax twice as fast in native membranes, at 17% smaller mode amplitude, while in light the decay rate of local fluctuations is 1.2-fold faster in inhibited membranes than in native membranes, at 56% higher amplitude. The disrupted electron transfer chain and the decreased proton motive force within the lumenal space partially explain the variations observed in the mechanical properties of the Synechocystis membranes, and further support the hypothesis that the photosynthetic process is tied to thylakoid rigidity in this type of cyanobacterial cell.
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Okamura E. Solution NMR to Quantify Mobility in Membranes: Diffusion, Protrusion, and Drug Transport Processes. Chem Pharm Bull (Tokyo) 2019; 67:308-315. [DOI: 10.1248/cpb.c18-00946] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Emiko Okamura
- Faculty of Pharmaceutical Sciences, Himeji Dokkyo University
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46
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The helix-to-sheet transition of an HIV-1 fusion peptide derivative changes the mechanical properties of lipid bilayer membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:565-572. [DOI: 10.1016/j.bbamem.2018.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 12/06/2018] [Accepted: 12/07/2018] [Indexed: 11/18/2022]
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47
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Ashkar R, Bilheux HZ, Bordallo H, Briber R, Callaway DJE, Cheng X, Chu XQ, Curtis JE, Dadmun M, Fenimore P, Fushman D, Gabel F, Gupta K, Herberle F, Heinrich F, Hong L, Katsaras J, Kelman Z, Kharlampieva E, Kneller GR, Kovalevsky A, Krueger S, Langan P, Lieberman R, Liu Y, Losche M, Lyman E, Mao Y, Marino J, Mattos C, Meilleur F, Moody P, Nickels JD, O'Dell WB, O'Neill H, Perez-Salas U, Peters J, Petridis L, Sokolov AP, Stanley C, Wagner N, Weinrich M, Weiss K, Wymore T, Zhang Y, Smith JC. Neutron scattering in the biological sciences: progress and prospects. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:1129-1168. [PMID: 30605130 DOI: 10.1107/s2059798318017503] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/12/2018] [Indexed: 12/11/2022]
Abstract
The scattering of neutrons can be used to provide information on the structure and dynamics of biological systems on multiple length and time scales. Pursuant to a National Science Foundation-funded workshop in February 2018, recent developments in this field are reviewed here, as well as future prospects that can be expected given recent advances in sources, instrumentation and computational power and methods. Crystallography, solution scattering, dynamics, membranes, labeling and imaging are examined. For the extraction of maximum information, the incorporation of judicious specific deuterium labeling, the integration of several types of experiment, and interpretation using high-performance computer simulation models are often found to be particularly powerful.
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Affiliation(s)
- Rana Ashkar
- Department of Physics, Virginia Polytechnic Institute and State University, 850 West Campus Drive, Blacksburg, VA 24061, USA
| | - Hassina Z Bilheux
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | | | - Robert Briber
- Materials Science and Engineeering, University of Maryland, 1109 Chemical and Nuclear Engineering Building, College Park, MD 20742, USA
| | - David J E Callaway
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Xiaolin Cheng
- Department of Medicinal Chemistry and Pharmacognosy, Ohio State University College of Pharmacy, 642 Riffe Building, Columbus, OH 43210, USA
| | - Xiang Qiang Chu
- Graduate School of China Academy of Engineering Physics, Beijing, 100193, People's Republic of China
| | - Joseph E Curtis
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Mark Dadmun
- Department of Chemistry, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Paul Fenimore
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - David Fushman
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA
| | - Frank Gabel
- Institut Laue-Langevin, Université Grenoble Alpes, CEA, CNRS, IBS, 38042 Grenoble, France
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Frederick Herberle
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Frank Heinrich
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Liang Hong
- Department of Physics and Astronomy, Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - John Katsaras
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zvi Kelman
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
| | - Eugenia Kharlampieva
- Department of Chemistry, University of Alabama at Birmingham, 901 14th Street South, Birmingham, AL 35294, USA
| | - Gerald R Kneller
- Centre de Biophysique Moléculaire, CNRS, Université d'Orléans, Chateau de la Source, Avenue du Parc Floral, Orléans, France
| | - Andrey Kovalevsky
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Susan Krueger
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Paul Langan
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Raquel Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Yun Liu
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Mathias Losche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Edward Lyman
- Department of Physics and Astrophysics, University of Delaware, Newark, DE 19716, USA
| | - Yimin Mao
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - John Marino
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
| | - Carla Mattos
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, USA
| | - Flora Meilleur
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Peter Moody
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, England
| | - Jonathan D Nickels
- Department of Physics, Virginia Polytechnic Institute and State University, 850 West Campus Drive, Blacksburg, VA 24061, USA
| | - William B O'Dell
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
| | - Hugh O'Neill
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Ursula Perez-Salas
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | | | - Loukas Petridis
- Materials Science and Engineeering, University of Maryland, 1109 Chemical and Nuclear Engineering Building, College Park, MD 20742, USA
| | - Alexei P Sokolov
- Department of Chemistry, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Christopher Stanley
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Norman Wagner
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Michael Weinrich
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Kevin Weiss
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Troy Wymore
- Graduate School of China Academy of Engineering Physics, Beijing, 100193, People's Republic of China
| | - Yang Zhang
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Jeremy C Smith
- Department of Medicinal Chemistry and Pharmacognosy, Ohio State University College of Pharmacy, 642 Riffe Building, Columbus, OH 43210, USA
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Chakraborty S, Abbasi A, Bothun GD, Nagao M, Kitchens CL. Phospholipid Bilayer Softening Due to Hydrophobic Gold Nanoparticle Inclusions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:13416-13425. [PMID: 30350687 DOI: 10.1021/acs.langmuir.8b02553] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Liposome-nanoparticle assemblies (LNAs) are vital in the context of novel targeted drug-delivery systems, in addition to investigating nanoparticle-lipid bilayer interactions. Quantifying membrane structural properties and dynamics in presence of nanoparticle inclusions provides a simple model to elucidate nanoparticle effects on membrane biophysical properties. We present experimental evidences of bilayer softening due to small hydrophobic gold nanoparticle inclusions. LNA structure has been investigated by a combination of cryo-transmission electron microscopy, dynamic light scattering, and small-angle neutron scattering. Neutron spin echo spectroscopy demonstrated a remarkable ∼15% bending modulus decrease for LNAs relative to pure liposomes. Clear dependence of bending modulus on gold nanoparticle diameter and concentration was observed from our observations. Our findings point toward local bilayer fluidization by nanoparticle inclusions leading to an overall bilayer softening. These findings add valuable information to liposomal drug-delivery vehicle design and membrane biophysics research.
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Affiliation(s)
- Saptarshi Chakraborty
- Department of Chemical and Biomolecular Engineering , Clemson University , Clemson , South Carolina 29634 , United States
| | - Akram Abbasi
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Michihiro Nagao
- NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
- Center for Exploration of Energy and Matter, Department of Physics , Indiana University , Bloomington , Indiana 47408 , United States
| | - Christopher L Kitchens
- Department of Chemical and Biomolecular Engineering , Clemson University , Clemson , South Carolina 29634 , United States
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49
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Allolio C, Haluts A, Harries D. A local instantaneous surface method for extracting membrane elastic moduli from simulation: Comparison with other strategies. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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50
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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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