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Osti NC, Jalarvo N, Mamontov E. Backscattering silicon spectrometer (BASIS): sixteen years in advanced materials characterization. MATERIALS HORIZONS 2024; 11:4535-4572. [PMID: 39162617 DOI: 10.1039/d4mh00690a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
Quasielastic neutron scattering (QENS) is an experimental technique that can measure parameters of mobility, such as diffusion jump rate and jump length, as well as localized relaxations of chemical species (molecules, ions, and segments) at atomic and nanometer length scales. Due to the high penetrative power of neutrons and their sensitivity to neutron scattering cross-section of chemical species, QENS can effectively probe mobility inside most bulk materials. This review focuses on QENS experiments performed using a neutron backscattering silicon spectrometer (BASIS) to explore the dynamics in various materials and understand their structure-property relationship. BASIS is a time-of-flight near-backscattering inverted geometry spectrometer with very high energy resolution (approximately 0.0035 meV of full width at half maximum), allowing measurements of dynamics on nano to picosecond timescales. The science areas studied with BASIS are diverse, with a focus on soft matter topics, including traditional biological and polymer science experiments, as well as measurements of fluids ranging from simple hydrocarbons and aqueous solutions to relatively complex room-temperature ionic liquids and deep-eutectic solvents, either in the bulk state or confined. Additionally, hydrogen confined in various materials is routinely measured on BASIS. Other topics successfully investigated at BASIS include quantum fluids, spin glasses, and magnetism. BASIS has been in the user program since 2007 at the Spallation Neutron Source of the Oak Ridge National Laboratory, an Office of Science User Facility supported by the U.S. Department of Energy. Over the past sixteen years, BASIS has contributed to various scientific disciplines, exploring the structure and dynamics of many chemical species and their fabrication for practical applications. A comprehensive review of BASIS contributions and capabilities would be an asset to the materials science community, providing insights into employing the neutron backscattering technique for advanced materials characterization.
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Affiliation(s)
- Naresh C Osti
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
| | - Niina Jalarvo
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
| | - Eugene Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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2
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Lee M, Lee E, Kim JH, Hwang H, Cho M, Sung J. Transport Dynamics of Water Molecules Confined between Lipid Membranes. J Phys Chem Lett 2024; 15:4437-4443. [PMID: 38626458 DOI: 10.1021/acs.jpclett.4c00323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
Water molecules confined between biological membranes exhibit a distinctive non-Gaussian displacement distribution, far different from that of bulk water. Here, we introduce a new transport equation for water molecules in the intermembrane space, quantitatively explaining molecular dynamics simulation results. We find that the unique transport dynamics of water molecules stems from the lateral diffusion coefficient fluctuation caused by their longitudinal motion in the direction perpendicular to the membranes. We also identify an interfacial region where water possesses distinct physical properties, which is unaffected by changes in the intermembrane separation.
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Affiliation(s)
- Minho Lee
- Creative Research Initiative Center for Chemical Dynamics in Living Cells, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Euihyun Lee
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78757, United States
| | - Ji-Hyun Kim
- Creative Research Initiative Center for Chemical Dynamics in Living Cells, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Hyonseok Hwang
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon-do 24341, Republic of Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Jaeyoung Sung
- Creative Research Initiative Center for Chemical Dynamics in Living Cells, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea
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Weiand E, Ewen JP, Roiter Y, Koenig PH, Page SH, Rodriguez-Ropero F, Angioletti-Uberti S, Dini D. Nanoscale friction of biomimetic hair surfaces. NANOSCALE 2023; 15:7086-7104. [PMID: 36987934 DOI: 10.1039/d2nr05545g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
We investigate the nanoscale friction between biomimetic hair surfaces using chemical colloidal probe atomic force microscopy experiments and nonequilibrium molecular dynamics simulations. In the experiments, friction is measured between water-lubricated silica surfaces functionalised with monolayers formed from either octadecyl or sulfonate groups, which are representative of the surfaces of virgin and ultimately bleached hair, respectively. In the simulations, friction is monitored between coarse-grained model hair surfaces with different levels of chemical damage, where a specified amount of grafted octadecyl groups are randomly replaced with sulfonate groups. The sliding velocity dependence of friction in the simulations can be described using an extended stress-augmented thermally activation model. As the damage level increases in the simulations, the friction coefficient generally increases, but its sliding velocity-dependence decreases. At low sliding velocities, which are closer to those encountered experimentally and physiologically, we observe a monotonic increase of the friction coefficient with damage ratio, which is consistent with our new experiments using biomimetic surfaces and previous ones using real hair. This observation demonstrates that modified surface chemistry, rather than roughness changes or subsurface damage, control the increase in nanoscale friction of bleached or chemically damaged hair. We expect the methods and biomimetic surfaces proposed here to be useful to screen the tribological performance of hair care formulations both experimentally and computationally.
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Affiliation(s)
- Erik Weiand
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK.
- Institute of Molecular Science and Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK
- Thomas Young Centre for the Theory and Simulation of Materials, Imperial College London, South Kensington Campus, SW7 2AZ London, UK
| | - James P Ewen
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK.
- Institute of Molecular Science and Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK
- Thomas Young Centre for the Theory and Simulation of Materials, Imperial College London, South Kensington Campus, SW7 2AZ London, UK
| | - Yuri Roiter
- Corporate Functions Analytical and Data & Modeling Sciences, Mason Business Center, The Procter and Gamble Company, Mason, 45040 Ohio, USA
| | - Peter H Koenig
- Corporate Functions Analytical and Data & Modeling Sciences, Mason Business Center, The Procter and Gamble Company, Mason, 45040 Ohio, USA
| | - Steven H Page
- Corporate Functions Analytical and Data & Modeling Sciences, Mason Business Center, The Procter and Gamble Company, Mason, 45040 Ohio, USA
| | - Francisco Rodriguez-Ropero
- Corporate Functions Analytical and Data & Modeling Sciences, Mason Business Center, The Procter and Gamble Company, Mason, 45040 Ohio, USA
| | | | - Daniele Dini
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK.
- Institute of Molecular Science and Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK
- Thomas Young Centre for the Theory and Simulation of Materials, Imperial College London, South Kensington Campus, SW7 2AZ London, UK
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Matsuo T, Cisse A, Plazanet M, Natali F, Koza MM, Ollivier J, Bicout DJ, Peters J. The dynamical Matryoshka model: 3. Diffusive nature of the atomic motions contained in a new dynamical model for deciphering local lipid dynamics. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183949. [PMID: 35508224 DOI: 10.1016/j.bbamem.2022.183949] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 04/06/2022] [Accepted: 04/25/2022] [Indexed: 11/17/2022]
Abstract
In accompanying papers [Bicout et al., BioRxiv https://doi.org/10.1101/2021.09.21.461198 (2021); Cissé et al., BioRxiv https://doi.org/10.1101/2022.03.30.486370 (2022)], a new model called Matryoshka model has been proposed to describe the geometry of atomic motions in phospholipid molecules in bilayers and multilamellar vesicles based on their quasielastic neutron scattering (QENS) spectra. Here, in order to characterize the relaxational aspects of this model, the energy widths of the QENS spectra of the samples were analyzed first in a model-free way. The spectra were decomposed into three Lorentzian functions, which are classified as slow, intermediate, and fast motions depending on their widths. The analysis provides the diffusion coefficients, residence times, and geometrical parameters for the three classes of motions. The results corroborate the parameter values such as the amplitudes and the mobile fractions of atomic motions obtained by the application of the Matryoshka model to the same samples. Since the current analysis was carried out independently of the development of the Matryoshka model, the present results enhance the validity of the model. The model will serve as a powerful tool to decipher the dynamics of lipid molecules not only in model systems, but also in more complex systems such as mixtures of different kinds of lipids or natural cell membranes.
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Affiliation(s)
- Tatsuhito Matsuo
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000 Grenoble, France; Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France; Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, 2-4 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Aline Cisse
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000 Grenoble, France; Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Marie Plazanet
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000 Grenoble, France
| | - Francesca Natali
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France; CNR-IOM, OGG, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Michael Marek Koza
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Jacques Ollivier
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Dominique J Bicout
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France; Univ. Grenoble Alpes, CNRS, Grenoble INP, VetAgro Sup, TIMC, 38000 Grenoble, France
| | - Judith Peters
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000 Grenoble, France; Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France; Institut Universitaire de France, France.
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Pal T, Paul R, Paul S. Phenylpropanoids on the Inhibition of β-Amyloid Aggregation and the Movement of These Molecules through the POPC Lipid Bilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7775-7790. [PMID: 35687701 DOI: 10.1021/acs.langmuir.2c00827] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Alzheimer's disease (AD), caused by Aβ aggregation, is a major concern in medical research. It is a neurodegenerative disorder, leading to a loss of cognitive abilities, which is still claiming the lives of many people all over the world. This poses a challenge before the scientific community to discover effective drugs which can prevent such toxic aggregation. Recent experimental findings suggest the potency of two naturally-occurring phenylpropanoids, Schizotenuin A (SCH) and Lycopic Acid B (LAB) which can effectively combat the deleterious effects of Aβ aggregation, although nothing is known about their mechanism of inhibition. In this work, we deal with an extensive computational study on the inhibitory effects of these inhibitors by using an all-atom molecular dynamics simulation to interpret the underlying mechanism of their inhibitory processes. A series of investigations is carried out while studying the various structural and conformational changes of the peptide chains in the absence and presence of inhibitors. To investigate the details of the interactions between the peptide residues and inhibitors, nonbonding energy calculations, the radial distribution function, the coordination number of water and inhibitor molecules around the peptide residues, and hydrogen-bonding interactions are calculated. The potential of mean force (PMF) is calculated to estimate aggregate formation from their free-energy profiles. It is seen that the hydrophobic core of the KLVFFAE undergoes aggregation and that these inhibitors show great promise in preventing the onset of AD in the future by preventing Aβ aggregation. Also, the translocation studies on these inhibitors through a model POPC lipid bilayer shed light on their permeation properties and biocompatibility.
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Affiliation(s)
- Triasha Pal
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
| | - Rabindranath Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
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Paul R, Bera S, Devi M, Paul S. Inhibition of Aβ 16–22 Peptide Aggregation by Small Molecules and Their Permeation through POPC Lipid Bilayer: Insight from Molecular Dynamics Simulation Study. J Chem Inf Model 2022; 62:5193-5207. [DOI: 10.1021/acs.jcim.1c01366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Rabindranath Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
| | - Siddhartha Bera
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
| | - Madhusmita Devi
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
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Franco LR, Park P, Chaimovich H, Coutinho K, Cuccovia IM, Lima FS. Simulations reveal that antimicrobial BP100 induces local membrane thinning, slows lipid dynamics and favors water penetration. RSC Adv 2022; 12:4573-4588. [PMID: 35425494 PMCID: PMC8981376 DOI: 10.1039/d1ra06267k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
MD simulations reveal that BP100 peptide induces local membrane thinning and negative curvature, slows lipid dynamics and increases the water life time in the lipid hydrophobic core and transmembrane water transport in the direction of the peptide.
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Affiliation(s)
| | - Peter Park
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Hernan Chaimovich
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Kaline Coutinho
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - Iolanda M. Cuccovia
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Filipe S. Lima
- Departamento de Química Fundamental, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Recife, Brazil
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Paul R, Paul S. Translocation of Endo-Functionalized Molecular Tubes across Different Lipid Bilayers: Atomistic Molecular Dynamics Simulation Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10376-10387. [PMID: 34415773 DOI: 10.1021/acs.langmuir.1c01594] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Various artificial receptors, such as calixarenes, cyclodextrins, cucurbit[n]urils, and their acyclic compounds, pliiar[n]arenes, deep cavitands, and molecular tweezers, can permeate the lipid membranes and they are used as drug carriers to improve the drug solubility, stability, and bioavailability. Inspired by these, we have employed atomistic molecular dynamics simulation to examine the effects of endo-functionalized molecular tubes or naphthotubes (host-1a and host-1b) on seven different types of model lipid bilayers and the permeation properties of these receptors through these model lipid bilayers. Lipid types include six model lipid bilayers (POPC, POPE, DOPC, POPG, DPPE, POPE/POPG) and one realistic membrane (Yeast). We observe that these receptors are spontaneously translocated toward these model lipid bilayer head regions and do not proceed further into these lipid bilayer tail regions (reside at the interface between lipid head and lipid tail region), except for the DPPE-containing systems. In the DPPE model lipid bilayer-containing systems (1a-dppe and 1b-dppe), receptor molecules are only adsorbed on the bilayer surface and reside at the interface between lipid head and water. This finding is also supported by the biased free-energy profiles of these translocation processes. Passive transport of these receptors may be possible through these model lipid bilayers (due to low barrier height), except for DPPE bilayer-containing systems (that have a very high energy barrier at the center). The results from these simulations provide insight into the biocompatibility of host-1a or host-1b in microscopic detail. Based on this work, more research is needed to fully comprehend the role of these synthesized receptors as a prospective drug carrier.
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Affiliation(s)
- Rabindranath Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
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Polańska Ż, Pietralik-Molińska Z, Wojciechowska D, Moliński A, Weiss M, Skrzypczak A, Kozak M. The Process of Binding and Releasing of Genetic Material from Lipoplexes Based on Trimeric Surfactants and Phospholipids. Int J Mol Sci 2021; 22:7744. [PMID: 34299360 PMCID: PMC8303235 DOI: 10.3390/ijms22147744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/12/2022] Open
Abstract
Nonviral vectors for gene therapy such as lipoplexes are characterized by low toxicity, high biocompatibility, and good transfection efficiency. Specifically, lipoplexes based on polymeric surfactants and phospholipids have great potential as gene carriers due to the increased ability to bind genetic material (multiplied positive electric charge) while lowering undesirable effects (the presence of lipids makes the system more like natural membranes). This study aimed to test the ability to bind and release genetic material by lipoplexes based on trimeric surfactants and lipid formulations of different compositions and to characterize formed complexes by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). The cytotoxicity of studied lipoplexes was tested on HeLa cells by the MTT cell viability assay and the dye exclusion test (trypan blue). The presence of lipids in the system lowered the surfactant concentration required for complexation (higher efficiency) and reduced the cytotoxicity of lipoplexes. Surfactant/lipids/DNA complexes were more stable than surfactant/DNA complexes. Surfactant molecules induced the genetic material condensation, but the presence of lipids significantly intensified this process. Systems based on trimeric surfactants and lipid formulations, particularly TRI_N and TRI_IMI systems, could be used as delivery carrier, and have proven to be highly effective, nontoxic, and universal for DNA of various lengths.
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Affiliation(s)
- Żaneta Polańska
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland; (Ż.P.); (Z.P.-M.); (D.W.); (A.M.)
| | - Zuzanna Pietralik-Molińska
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland; (Ż.P.); (Z.P.-M.); (D.W.); (A.M.)
| | - Daria Wojciechowska
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland; (Ż.P.); (Z.P.-M.); (D.W.); (A.M.)
| | - Augustyn Moliński
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland; (Ż.P.); (Z.P.-M.); (D.W.); (A.M.)
- NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Pastowskiej 3, 61-614 Poznań, Poland
| | - Marek Weiss
- Faculty of Materials Engineering and Technical Physics, Institute of Physics, Poznań University of Technology, Piotrowo 3, 60-965 Poznań, Poland;
| | - Andrzej Skrzypczak
- Faculty of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań, Poland;
| | - Maciej Kozak
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland; (Ż.P.); (Z.P.-M.); (D.W.); (A.M.)
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Borocci S, Bozzuto G, Bombelli C, Ceccacci F, Formisano G, Stringaro A, Molinari A, Mancini G. How stereochemistry of lipid components can affect lipid organization and the route of liposome internalization into cells. NANOSCALE 2021; 13:11976-11993. [PMID: 34212969 DOI: 10.1039/d1nr02175c] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Though liposome-based drugs are in clinical use, the mechanism of cell internalization of liposomes is yet an object of controversy. The present experimental investigation, carried out on human glioblastoma cells, indicated different internalization routes for two diastereomeric liposomes. Molecular dynamics simulations of the lipid bilayers of the two formulations indicated that the different stereochemistry of a lipid component controls some parameters such as area per lipid molecule and fluidity of lipid membranes, surface potential and water organization at the lipid/water interface, all of which affect the interaction with biomolecules and cell components.
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Affiliation(s)
- Stefano Borocci
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università degli Studi della Tuscia, L.go dell'Università, s.n.c., 01100 Viterbo, Italy.
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Paul R, Mitra A, Paul S. Phase separation property of a hydrophobic deep eutectic solvent-water binary mixture: A molecular dynamics simulation study. J Chem Phys 2021; 154:244504. [PMID: 34241334 DOI: 10.1063/5.0052200] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Over the past decade, deep eutectic solvents (DESs) have earned applicability in numerous fields as non-flammable, non-volatile, and greener alternatives to conventional organic solvents. In a first of its kind, a hydrophobic DES composed of a 1:1 mixture of oleic acid and lidocaine was recently reported, possessing a lower critical solution temperature in water. The thermoreversible phase property of this DES-water system was utilized to sequester out dye molecules from their aqueous solutions. In this article, we explore the phase separation phenomena for this particular DES in its aqueous solution using an all-atom molecular dynamics simulation. A 50 wt. % solution of the DES in water was studied at three different temperatures (253, 293, and 313 K) to understand the various molecular interactions that dictate the phase segregation property of these systems. In this work, we have elaborated on the importance of hydrogen bonding interactions and the non-bonding interactions between the components and the competition between the two that leads to phase separation. Overall, we observe that the increase in unfavorable interaction between the DES components and water with increasing temperature determines the phase separation behavior. We have also studied the modification in the dynamical properties of water molecules close to the phase boundary. Such molecular insights would be beneficial for designing novel solvent systems that can be used as extraction-based media in industries.
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Affiliation(s)
- Rabindranath Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Aritra Mitra
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
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12
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Site-Specific Peptide Probes Detect Buried Water in a Lipid Membrane. Biophys J 2019; 116:1692-1700. [PMID: 31000156 DOI: 10.1016/j.bpj.2019.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 01/08/2023] Open
Abstract
Transmembrane peptides contain polar residues in the interior of the membrane, which may alter the electrostatic environment and favor hydration in the otherwise nonpolar environment of the membrane core. Here, we demonstrate a general, nonperturbative strategy to probe hydration of the peptide backbone at specific depths within the bilayer using a combination of site-specific isotope labels, ultrafast two-dimensional infrared spectroscopy, and spectral modeling based on molecular dynamics simulations. Our results show that the amphiphilic pH-low insertion peptide supports a highly heterogeneous environment, with significant backbone hydration of nonpolar residues neighboring charged residues. For example, a leucine residue located as far as 1 nm into the hydrophobic bulk reports hydrogen-bonded populations as high as ∼20%. These findings indicate that the polar nature of these residues may facilitate the transport of water molecules into the hydrophobic core of the membrane.
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13
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Selvam B, Mittal S, Shukla D. Free Energy Landscape of the Complete Transport Cycle in a Key Bacterial Transporter. ACS CENTRAL SCIENCE 2018; 4:1146-1154. [PMID: 30276247 PMCID: PMC6161048 DOI: 10.1021/acscentsci.8b00330] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Indexed: 05/21/2023]
Abstract
PepTSo is a proton-coupled bacterial symporter, from the major facilitator superfamily (MFS), which transports di-/tripeptide molecules. The recently obtained crystal structure of PepTSo provides an unprecedented opportunity to gain an understanding of functional insights of the substrate transport mechanism. Binding of the proton and peptide molecule induces conformational changes into occluded (OC) and outward-facing (OF) states, which we are able to characterize using molecular dynamics (MD) simulations. The structural knowledge of the OC and OF state is important to fully understand the major energy barrier associated with the transport cycle. In order to gain functional insight into the interstate dynamics, we performed extensive all atom MD simulations. The Markov state model was constructed to identify the free energy barriers between the states, and kinetic information on intermediate pathways was obtained using the transition pathway theory (TPT). TPT shows that the OF state is obtained by the movement of TM1 and TM7 at the extracellular side approximately 12-16 Å away from each other, and the inward movement of TM4 and TM10 at the intracellular halves to 3-4 Å characterizes the OC state. Helix distance distributions obtained from MD simulations were compared with experimental double electron-electron resonance spectroscopy and were found to be in excellent agreement with previous studies. We also predicted the optimal positions for placement of methane thiosulfonate spin label probes to capture the slowest protein dynamics. Our finding sheds light on the conformational cycle of this key membrane transporter and the functional relationships between the multiple intermediate states.
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Affiliation(s)
- Balaji Selvam
- Department of Chemical and Biomolecular Engineering, Center for Biophysics and Quantitative
Biology, and Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois, United States
| | - Shriyaa Mittal
- Department of Chemical and Biomolecular Engineering, Center for Biophysics and Quantitative
Biology, and Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois, United States
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, Center for Biophysics and Quantitative
Biology, and Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois, United States
- E-mail:
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14
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Mesoporous silica for drug delivery: Interactions with model fluorescent lipid vesicles and live cells. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 178:19-26. [DOI: 10.1016/j.jphotobiol.2017.10.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 10/13/2017] [Accepted: 10/25/2017] [Indexed: 01/25/2023]
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15
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Dynamic processes in biological membrane mimics revealed by quasielastic neutron scattering. Chem Phys Lipids 2017; 206:28-42. [DOI: 10.1016/j.chemphyslip.2017.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/22/2017] [Accepted: 05/25/2017] [Indexed: 12/15/2022]
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16
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Miskowiec A, Buck ZN, Hansen FY, Kaiser H, Taub H, Tyagi M, Diallo SO, Mamontov E, Herwig KW. On the structure and dynamics of water associated with single-supported zwitterionic and anionic membranes. J Chem Phys 2017; 146:125102. [DOI: 10.1063/1.4978677] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- A. Miskowiec
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - Z. N. Buck
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - F. Y. Hansen
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark
| | - H. Kaiser
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - H. Taub
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - M. Tyagi
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - S. O. Diallo
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E. Mamontov
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - K. W. Herwig
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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17
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Madsen JJ, Fristrup P, Peters GH. Theoretical Assessment of Fluorinated Phospholipids in the Design of Liposomal Drug-Delivery Systems. J Phys Chem B 2016; 120:9661-71. [DOI: 10.1021/acs.jpcb.6b07206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jesper J. Madsen
- Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Peter Fristrup
- Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Günther H. Peters
- Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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18
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Lee BL, Kuczera K, Middaugh CR, Jas GS. Permeation of the three aromatic dipeptides through lipid bilayers: Experimental and computational study. J Chem Phys 2016; 144:245103. [DOI: 10.1063/1.4954241] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Brent L. Lee
- Department of Chemistry, The University of Kansas, Lawrence, Kansas 66045, USA
| | - Krzysztof Kuczera
- Department of Chemistry, The University of Kansas, Lawrence, Kansas 66045, USA
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas 66045, USA
| | - C. Russell Middaugh
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66047, USA
| | - Gouri S. Jas
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66047, USA
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19
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Inelastic and quasi-elastic neutron scattering spectrometers in J-PARC. Biochim Biophys Acta Gen Subj 2016; 1861:3651-3660. [PMID: 27156489 DOI: 10.1016/j.bbagen.2016.04.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 11/20/2022]
Abstract
J-PARC, Japan Proton Accelerator Research Complex provides short pulse proton beam at a repetition rate 25Hz and the maximum power is expected to be 1MW. Materials and Life Science Experimental Facility (MLF) has 23 neutron beam ports and 21 instruments have already been operated or under construction/commissioning. There are 6 inelastic/quasi-elastic neutron scattering spectrometers and the complementary use of these spectrometers will open new insight for life science. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.
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20
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Rønnest AK, Peters GH, Hansen FY, Taub H, Miskowiec A. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes. J Chem Phys 2016; 144:144904. [DOI: 10.1063/1.4945278] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- A. K. Rønnest
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark
| | - G. H. Peters
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark
| | - F. Y. Hansen
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark
| | - H. Taub
- Department of Physics and Astronomy and the University of Missouri Research Reactor,University of Missouri, Columbia, Missouri 65211, USA
| | - A. Miskowiec
- Department of Physics and Astronomy and the University of Missouri Research Reactor,University of Missouri, Columbia, Missouri 65211, USA
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21
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Rifici S, D’Angelo G, Crupi C, Branca C, Conti Nibali V, Corsaro C, Wanderlingh U. Influence of Alcohols on the Lateral Diffusion in Phospholipid Membranes. J Phys Chem B 2016; 120:1285-90. [DOI: 10.1021/acs.jpcb.5b11427] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simona Rifici
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Giovanna D’Angelo
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Cristina Crupi
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Caterina Branca
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Valeria Conti Nibali
- Institute
for Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Carmelo Corsaro
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Ulderico Wanderlingh
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
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22
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Toppozini L, Roosen-Runge F, Bewley RI, Dalgliesh RM, Perring T, Seydel T, Glyde HR, García Sakai V, Rheinstädter MC. Anomalous and anisotropic nanoscale diffusion of hydration water molecules in fluid lipid membranes. SOFT MATTER 2015; 11:8354-8371. [PMID: 26338138 DOI: 10.1039/c5sm01713k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have studied nanoscale diffusion of membrane hydration water in fluid-phase lipid bilayers made of 1,2-dimyristoyl-3-phosphocholine (DMPC) using incoherent quasi-elastic neutron scattering. Dynamics were fit directly in the energy domain using the Fourier transform of a stretched exponential. By using large, 2-dimensional detectors, lateral motions of water molecules and motions perpendicular to the membranes could be studied simultaneously, resulting in 2-dimensional maps of relaxation time, τ, and stretching exponent, β. We present experimental evidence for anomalous (sub-diffusive) and anisotropic diffusion of membrane hydration water molecules over nanometer distances. By combining molecular dynamics and Brownian dynamics simulations, the potential microscopic origins for the anomaly and anisotropy of hydration water were investigated. Bulk water was found to show intrinsic sub-diffusive motion at time scales of several picoseconds, likely related to caging effects. In membrane hydration water, however, the anisotropy of confinement and local dynamical environments leads to an anisotropy of relaxation times and stretched exponents, indicative of anomalous dynamics.
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Affiliation(s)
- Laura Toppozini
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.
| | | | | | | | - Toby Perring
- ISIS, Rutherford Appleton Laboratory, Didcot, UK
| | | | - Henry R Glyde
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, USA
| | | | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.
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23
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Abstract
It is commonly assumed that the structure of water at a lipid-water interface is influenced mostly in the first hydration layer. However, recent results from different experimental methods show that perturbation extends through several hydration layers. Due to its low light penetration depth, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is specifically suited to study interlamellar water structure in multibilayers. Results obtained by this technique confirm the long-range water structure disturbance. Consequently, in confined membrane environments nearly all water molecules can be perturbed. It is important to note that the behavior of confined water molecules differs significantly in samples prepared in excess water and in partially hydrated samples. We show in what manner the interlamellar water perturbation is influenced by the hydration level and how it is sequentially modified with a step-by-step dehydration of samples either by water evaporation or by osmotic pressure. Our results also indicate that besides different levels of hydration the lipid-water interaction is modulated by different lipid headgroups and different lipid phases as well. Therefore, modification of interlamellar water properties may clarify the role of water-mediated effects in biological processes.
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Affiliation(s)
- Zoran Arsov
- Laboratory of Biophysics, Department of Solid State Physics, "Jozef Stefan" Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
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24
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Yang J, Calero C, Martí J. Diffusion and spectroscopy of water and lipids in fully hydrated dimyristoylphosphatidylcholine bilayer membranes. J Chem Phys 2014; 140:104901. [PMID: 24628199 DOI: 10.1063/1.4867385] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Microscopic structure and dynamics of water and lipids in a fully hydrated dimyristoylphosphatidylcholine phospholipid lipid bilayer membrane in the liquid-crystalline phase have been analyzed with all-atom molecular dynamics simulations based on the recently parameterized CHARMM36 force field. The diffusive dynamics of the membrane lipids and of its hydration water, their reorientational motions as well as their corresponding spectral densities, related to the absorption of radiation, have been considered for the first time using the present force field. In addition, structural properties such as density and pressure profiles, a deuterium-order parameter, surface tension, and the extent of water penetration in the membrane have been analyzed. Molecular self-diffusion, reorientational motions, and spectral densities of atomic species reveal a variety of time scales playing a role in membrane dynamics. The mechanisms of lipid motion strongly depend on the time scale considered, from fast ballistic translation at the scale of picoseconds (effective diffusion coefficients of the order of 10(-5) cm(2)/s) to diffusive flow of a few lipids forming nanodomains at the scale of hundreds of nanoseconds (diffusion coefficients of the order of 10(-8) cm(2)/s). In the intermediate regime of sub-diffusion, collisions with nearest neighbors prevent the lipids to achieve full diffusion. Lipid reorientations along selected directions agree well with reported nuclear magnetic resonance data and indicate two different time scales, one about 1 ns and a second one in the range of 2-8 ns. We associated the two time scales of reorientational motions with angular distributions of selected vectors. Calculated spectral densities corresponding to lipid and water reveal an overall good qualitative agreement with Fourier transform infrared spectroscopy experiments. Our simulations indicate a blue-shift of the low frequency spectral bands of hydration water as a result of its interaction with lipids. We have thoroughly analyzed the physical meaning of all spectral features from lipid atomic sites and correlated them with experimental data. Our findings include a "wagging of the tails" frequency around 30 cm(-1), which essentially corresponds to motions of the tail-group along the instantaneous plane formed by the two lipid tails, i.e., in-plane oscillations are clearly of bigger importance than those along the normal-to-the plane direction.
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Affiliation(s)
- J Yang
- Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia, Spain
| | - C Calero
- Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia, Spain
| | - J Martí
- Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia, Spain
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25
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Feng JW, Ding HM, Ma YQ. Controlling water flow inside carbon nanotube with lipid membranes. J Chem Phys 2014; 141:094901. [DOI: 10.1063/1.4893964] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Rifici S, Corsaro C, Crupi C, Nibali VC, Branca C, D'Angelo G, Wanderlingh U. Lipid diffusion in alcoholic environment. J Phys Chem B 2014; 118:9349-55. [PMID: 25036819 DOI: 10.1021/jp504218v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We have studied the effects of a high concentration of butanol and octanol on the phase behavior and on the lateral mobility of 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) by means of differential scanning calorimetry and pulsed-gradient stimulated-echo (PGSTE) NMR spectroscopy. A lowering of the lipid transition from the gel to the liquid-crystalline state for the membrane-alcohol systems has been observed. NMR measurements reveal three distinct diffusions in the DPPC-alcohol systems, characterized by a high, intermediate, and slow diffusivity, ascribed to the water, the alcohol, and the lipid, respectively. The lipid diffusion process is promoted in the liquid phase while it is hindered in the interdigitated phase due to the presence of alcohols. Furthermore, in the interdigitated phase, lipid lateral diffusion coefficients show a slight temperature dependence. To the best of our knowledge, this is the first time that lateral diffusion coefficients on alcohol with so a long chain, and at low temperatures, are reported. By the Arrhenius plots of the temperature dependence of the diffusion coefficients, we have evaluated the apparent activation energy in both the liquid and in the interdigitated phase. The presence of alcohol increases this value in both phases. An explanation in terms of a free volume model that takes into account also for energy factors is proposed.
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Affiliation(s)
- Simona Rifici
- Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina , Messina, Italy
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27
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Duyn JH. Frequency shifts in the myelin water compartment. Magn Reson Med 2014; 71:1953-5. [PMID: 24700549 DOI: 10.1002/mrm.24983] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/09/2013] [Accepted: 09/13/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Jeff H Duyn
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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28
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Jelescu IO, Ciobanu L, Geffroy F, Marquet P, Le Bihan D. Effects of hypotonic stress and ouabain on the apparent diffusion coefficient of water at cellular and tissue levels in Aplysia. NMR IN BIOMEDICINE 2014; 27:280-290. [PMID: 24403001 DOI: 10.1002/nbm.3061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/03/2013] [Accepted: 11/20/2013] [Indexed: 06/03/2023]
Abstract
There is evidence that physiological or pathological cell swelling is associated with a decrease of the apparent diffusion coefficient (ADC) of water in tissues, as measured with MRI. However the mechanism remains unclear. Magnetic resonance microscopy, performed on small tissue samples, has the potential to distinguish effects occurring at cellular and tissue levels. A three-dimensional diffusion prepared fast imaging with steady-state free precession sequence for MR microscopy was implemented on a 17.2 T imaging system and used to investigate the effect of two biological challenges known to cause cell swelling, exposure to a hypotonic solution or to ouabain, on Aplysia nervous tissue. The ADC was measured inside isolated neuronal soma and in the region of cell bodies of the buccal ganglia. Both challenges resulted in an ADC increase inside isolated neuronal soma (+31 ± 24% and +30 ± 11%, respectively) and an ADC decrease at tissue level in the buccal ganglia (-12 ± 5% and -18 ± 8%, respectively). A scenario involving a layer of water molecules bound to the inflating cell membrane surface is proposed to reconcile this apparent discrepancy.
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Affiliation(s)
- Ileana Ozana Jelescu
- NeuroSpin, Commissariat à l'Energie Atomique et aux Energies Alternatives, Gif-sur-Yvette, France
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29
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von Hansen Y, Gekle S, Netz RR. Anomalous anisotropic diffusion dynamics of hydration water at lipid membranes. PHYSICAL REVIEW LETTERS 2013; 111:118103. [PMID: 24074121 DOI: 10.1103/physrevlett.111.118103] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Indexed: 06/02/2023]
Abstract
The diffusional water dynamics in the hydration layer of a dipalmitoylphosphatidylcholine bilayer is studied using molecular dynamics simulations. By mapping the perpendicular water motion on the ordinary diffusion equation, we disentangle free energetic and friction effects and show that perpendicular diffusion is strongly reduced. The lateral water motion exhibits anomalous diffusion up to several nanoseconds and is characterized by even further decreased diffusion coefficients, which by comparison with coarse-grained simulations are explained by the transient corrugated effective free energy landscape imposed by the lipids. This is in contrast to homogenous surfaces, where boundary hydrodynamic theory quantitatively predicts the anisotropy of water diffusion.
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Affiliation(s)
- Yann von Hansen
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany and Physics Department, Technische Universität München, 85748 Garching, Germany
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