1
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Bottacchiari M, Gallo M, Bussoletti M, Casciola CM. The diffuse interface description of fluid lipid membranes captures key features of the hemifusion pathway and lateral stress profile. PNAS NEXUS 2024; 3:pgae300. [PMID: 39114574 PMCID: PMC11304589 DOI: 10.1093/pnasnexus/pgae300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 07/09/2024] [Indexed: 08/10/2024]
Abstract
Topological transitions of lipid membranes are ubiquitous in key biological processes for cell life, like neurotransmission, fertilization, morphogenesis, and viral infections. Despite this, they are not well understood due to their multiscale nature, which limits the use of molecular models and calls for a mesoscopic approach such as the celebrated Canham-Helfrich one. Unfortunately, such a model cannot handle topological transitions, hiding the crucial involved forces and the appearance of the experimentally observed hemifused intermediates. In this work, we describe the membrane as a diffuse interface preserving the Canham-Helfrich elasticity. We show that pivotal features of the hemifusion pathway are captured by this mesoscopic approach, e.g. a (meta)stable hemifusion state and the fusogenic behavior of negative monolayer spontaneous curvatures. The membrane lateral stress profile is calculated as a function of the elastic rigidities, yielding a coarse-grained version of molecular models findings. Insights into the fusogenic mechanism are reported and discussed.
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Affiliation(s)
- Matteo Bottacchiari
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, via Antonio Scarpa 16, Rome 00161, Italy
- Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, via Eudossiana 18, Rome 00184, Italy
| | - Mirko Gallo
- Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, via Eudossiana 18, Rome 00184, Italy
| | - Marco Bussoletti
- Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, via Eudossiana 18, Rome 00184, Italy
| | - Carlo M Casciola
- Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, via Eudossiana 18, Rome 00184, Italy
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2
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Häfner G, Müller M. Reaction-driven assembly: controlling changes in membrane topology by reaction cycles. SOFT MATTER 2023; 19:7281-7292. [PMID: 37605887 DOI: 10.1039/d3sm00876b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Chemical reaction cycles are prototypical examples how to drive systems out of equilibrium and introduce novel, life-like properties into soft-matter systems. We report simulations of amphiphilic molecules in aqueous solution. The molecule's head group is permanently hydrophilic, whereas the reaction cycle switches the molecule's tail from hydrophilic (precursor) to hydrophobic (amphiphile) and vice versa. The reaction cycle leads to an arrest in coalescence and results in uniform vesicle sizes that can be controlled by the reaction rate. Using a continuum description and particle-based simulation, we study the scaling of the vesicle size with the reaction rate. The chemically active vesicles are inflated by precursor, imparting tension onto the membrane and, for specific parameters, stabilize pores.
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Affiliation(s)
- Gregor Häfner
- Institute for Theoretical Physics, Georg-August University, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
- Max Planck School Matter to Life, Jahnstraße 29, 69120 Heidelberg, Germany
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August University, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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3
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Ledum M, Sen S, Li X, Carrer M, Feng Y, Cascella M, Bore SL. HylleraasMD: A Domain Decomposition-Based Hybrid Particle-Field Software for Multiscale Simulations of Soft Matter. J Chem Theory Comput 2023; 19:2939-2952. [PMID: 37130290 DOI: 10.1021/acs.jctc.3c00134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We present HylleraasMD (HyMD), a comprehensive implementation of the recently proposed Hamiltonian formulation of hybrid particle-field molecular dynamics. The methodology is based on a tunable, grid-independent length-scale of coarse graining, obtained by filtering particle densities in reciprocal space. This enables systematic convergence of energies and forces by grid refinement, also eliminating nonphysical force aliasing. Separating the time integration of fast modes associated with internal molecular motion from slow modes associated with their density fields, we enable the first time-reversible, energy-conserving hybrid particle-field simulations. HyMD comprises the optional use of explicit electrostatics, which, in this formalism, corresponds to the long-range potential in particle-mesh Ewald. We demonstrate the ability of HyMD to perform simulations in the microcanonical and canonical ensembles with a series of test cases, comprising lipid bilayers and vesicles, surfactant micelles, and polypeptide chains, comparing our results to established literature. An on-the-fly increase of the characteristic coarse-grain length significantly speeds up dynamics, accelerating self-diffusion and leading to expedited aggregation. Exploiting this acceleration, we find that the time scales involved in the self-assembly of polymeric structures can lie in the tens to hundreds of picoseconds instead of the multimicrosecond regime observed with comparable coarse-grained models.
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Affiliation(s)
- Morten Ledum
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, PO Box 1033 Blindern, 0315 Oslo, Norway
| | - Samiran Sen
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, PO Box 1033 Blindern, 0315 Oslo, Norway
| | - Xinmeng Li
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, PO Box 1033 Blindern, 0315 Oslo, Norway
| | - Manuel Carrer
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, PO Box 1033 Blindern, 0315 Oslo, Norway
| | - Yu Feng
- Berkeley Center for Cosmological Physics and Department of Physics, University of California, Berkeley, California 94720, United States
| | - Michele Cascella
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, PO Box 1033 Blindern, 0315 Oslo, Norway
| | - Sigbjørn Løland Bore
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
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4
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Sen S, Ledum M, Bore SL, Cascella M. Soft Matter under Pressure: Pushing Particle-Field Molecular Dynamics to the Isobaric Ensemble. J Chem Inf Model 2023; 63:2207-2217. [PMID: 36976890 PMCID: PMC10091448 DOI: 10.1021/acs.jcim.3c00186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Indexed: 03/29/2023]
Abstract
Hamiltonian hybrid particle-field molecular dynamics is a computationally efficient method to study large soft matter systems. In this work, we extend this approach to constant-pressure (NPT) simulations. We reformulate the calculation of internal pressure from the density field by taking into account the intrinsic spread of the particles in space, which naturally leads to a direct anisotropy in the pressure tensor. The anisotropic contribution is crucial for reliably describing the physics of systems under pressure, as demonstrated by a series of tests on analytical and monatomic model systems as well as realistic water/lipid biphasic systems. Using Bayesian optimization, we parametrize the field interactions of phospholipids to reproduce the structural properties of their lamellar phases, including area per lipid, and local density profiles. The resulting model excels in providing pressure profiles in qualitative agreement with all-atom modeling, and surface tension and area compressibility in quantitative agreement with experimental values, indicating the correct description of long-wavelength undulations in large membranes. Finally, we demonstrate that the model is capable of reproducing the formation of lipid droplets inside a lipid bilayer.
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Affiliation(s)
- Samiran Sen
- Hylleraas Centre for Quantum
Molecular Sciences and Department of Chemistry, University of Oslo, P.O. Box 1033
Blindern, 0315 Oslo, Norway
| | - Morten Ledum
- Hylleraas Centre for Quantum
Molecular Sciences and Department of Chemistry, University of Oslo, P.O. Box 1033
Blindern, 0315 Oslo, Norway
| | - Sigbjørn Løland Bore
- Hylleraas Centre for Quantum
Molecular Sciences and Department of Chemistry, University of Oslo, P.O. Box 1033
Blindern, 0315 Oslo, Norway
| | - Michele Cascella
- Hylleraas Centre for Quantum
Molecular Sciences and Department of Chemistry, University of Oslo, P.O. Box 1033
Blindern, 0315 Oslo, Norway
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5
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Pan F, Sun L, Li S. Dynamic Processes and Mechanical Properties of Lipid-Nanoparticle Mixtures. Polymers (Basel) 2023; 15:polym15081828. [PMID: 37111975 PMCID: PMC10144953 DOI: 10.3390/polym15081828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/23/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
In this study, we investigate the dynamic processes and mechanical properties of lipid nanoparticle mixtures in a melt via dissipation particle dynamic simulation. By investigating the distribution of nanoparticles in lamellar and hexagonal lipid matrices in equilibrium state and dynamic processes, we observe that the morphology of such composites depends not only on the geometric features of the lipid matrix but also on the concentration of nanoparticles. The dynamic processes are also demonstrated by calculating the average radius of gyration, which indicates the isotropic conformation of lipid molecules in the x-y plane and that the lipid chains are stretched in the z direction with the addition of nanoparticles. Meanwhile, we predict the mechanical properties of lipid-nanoparticle mixtures in lamellar structures by analyzing the interfacial tensions. Results show that the interfacial tension decreased with the increase in nanoparticle concentration. These results provide molecular-level information for the rational and a priori design of new lipid nanocomposites with ad hoc tailored properties.
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Affiliation(s)
- Fan Pan
- School of Data Science and Artificial Intelligence, Wenzhou University of Technology, Wenzhou 325035, China
| | - Lingling Sun
- Department of Physics, Wenzhou University, Wenzhou 325035, China
| | - Shiben Li
- Department of Physics, Wenzhou University, Wenzhou 325035, China
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6
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Müller M, Abetz V. Nonequilibrium Processes in Polymer Membrane Formation: Theory and Experiment. Chem Rev 2021; 121:14189-14231. [PMID: 34032399 DOI: 10.1021/acs.chemrev.1c00029] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Porous polymer and copolymer membranes are useful for ultrafiltration of functional macromolecules, colloids, and water purification. In particular, block copolymer membranes offer a bottom-up approach to form isoporous membranes. To optimize permeability, selectivity, longevity, and cost, and to rationally design fabrication processes, direct insights into the spatiotemporal structure evolution are necessary. Because of a multitude of nonequilibrium processes in polymer membrane formation, theoretical predictions via continuum models and particle simulations remain a challenge. We compiled experimental observations and theoretical approaches for homo- and block copolymer membranes prepared by nonsolvent-induced phase separation and highlight the interplay of multiple nonequilibrium processes─evaporation, solvent-nonsolvent exchange, diffusion, hydrodynamic flow, viscoelasticity, macro- and microphase separation, and dynamic arrest─that dictates the complex structure of the membrane on different scales.
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Affiliation(s)
- Marcus Müller
- Georg-August Universität, Institut für Theoretische Physik, 37073 Göttingen, Germany
| | - Volker Abetz
- Helmholtz-Zentrum Hereon, Institut für Membranforschung, 21502 Geesthacht, Germany.,Universität Hamburg, Institut für Physikalische Chemie, 20146 Hamburg, Germany
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7
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Chen Y, Wang Z, Ji Y, He L, Wang X, Li S. Asymmetric Lipid Membranes under Shear Flows: A Dissipative Particle Dynamics Study. MEMBRANES 2021; 11:655. [PMID: 34564472 PMCID: PMC8465239 DOI: 10.3390/membranes11090655] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/12/2021] [Accepted: 08/20/2021] [Indexed: 12/03/2022]
Abstract
We investigate the phase behavior of the asymmetric lipid membranes under shear flows, using the dissipative particle dynamics simulation. Two cases, the weak and strong shear flows, are considered for the asymmetric lipid microstructures. Three typical asymmetric structures, the membranes, tubes, and vesicle, are included in the phase diagrams, where the effect of two different types of lipid chain length on the formation of asymmetric membranes is evaluated. The dynamic processes are demonstrated for the asymmetric membranes by calculating the average radius of gyration and shape factor. The result indicates that different shear flows will affect the shape of the second type of lipid molecules; the shape of the first type of lipid molecules is more stable than that of the second type of lipid molecules. The mechanical properties are investigated for the asymmetric membranes by analyzing the interface tension. The results reveal an absolute pressure at the junctions of different types of particles under the weak shear flow; the other positions are almost in a state of no pressure; there is almost no pressure inside the asymmetric lipid membrane structure under the strong shear flow. The findings will help us to understand the potential applications of asymmetric lipid microstructures in the biological and medical fields.
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Affiliation(s)
| | | | | | | | | | - Shiben Li
- Department of Physics, Wenzhou University, Wenzhou 325035, China; (Y.C.); (Z.W.); (Y.J.); (L.H.); (X.W.)
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8
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Noguchi H. Virtual bending method to calculate bending rigidity, saddle-splay modulus, and spontaneous curvature of thin fluid membranes. Phys Rev E 2020; 102:053315. [PMID: 33327149 DOI: 10.1103/physreve.102.053315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 11/02/2020] [Indexed: 11/07/2022]
Abstract
A method to calculate the bending rigidity κ, saddle-splay modulus κ[over ¯], and spontaneous curvature C_{0} of a fluid membrane is proposed. Virtual work for the bending deformations into cylindrical and spherical shapes is calculated for a flat membrane. This method does not require a force decomposition, unlike the existing stress-profile method. The first derivative of the deformation gives κC_{0} and is a discrete form of the first moment of the stress profile. The second derivatives give κ and κ[over ¯] and include the variance terms of the first derivatives, which are not accounted for in the stress-profile method. This method is examined for a solvent-free meshless membrane model and a dissipative-particle-dynamics two-bead amphiphilic molecular model. It is concluded that κ and κ[over ¯] of a thin membrane can be accurately calculated, whereas for a thick membrane or one with an explicit solvent, a further extension to include the volume-fluctuation effects is required for an accurate estimation. The amplitude of the volume-fluctuation effects can be evaluated using the parameter dependence in the present method.
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Affiliation(s)
- Hiroshi Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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9
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Yang Y, Bu X, Zhang X. Regulation Mechanism of Bubbling Deformation and Fracture Toughness of the Membrane by Asymmetric Phospholipids: A Model System Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:10138-10146. [PMID: 32787040 DOI: 10.1021/acs.langmuir.0c01580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dynamic regulation of the deformation modulus and fracture toughness of a membrane is critical to organelles and cells for matching their conflicting needs of resilient and fractured behaviors. These properties implement the protection of the function in the normal condition and the fission function in the endocytosis condition of a membrane. Naturally, a membrane contains phospholipids that have different hydrophilic and hydrophobic group length. The diffusion and aggregation of the phospholipids with asymmetry of the hydrophilic-hydrophobic ratio on the membrane play a key role in regulating the mechanical behaviors passively to the external force. In present work, the effects of the asymmetry of phospholipids on the bubbling deformation and fracture toughness of the membrane to external stretching are investigated in a model system. A disk-shaped micelle formed from the blend of symmetric and asymmetric diblock copolymers in a selective solvent is considered as the membrane sheet. Its mechanically responsive behaviors are investigated by self-consistent field theory. By analyzing the evolution of different components during the stretching process, the mechanism of formation of the bubbling structure is revealed. Moreover, the fracture toughness depending on the asymmetry of the phospholipids is determined quantitatively.
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Affiliation(s)
- Yang Yang
- School of Science, Beijing Jiaotong University, Beijing 100044, PR China
| | - Xiangyu Bu
- School of Science, Beijing Jiaotong University, Beijing 100044, PR China
| | - Xinghua Zhang
- School of Science, Beijing Jiaotong University, Beijing 100044, PR China
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10
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Winkeljohn CM, Himberg B, Vanegas JM. Balance of Solvent and Chain Interactions Determines the Local Stress State of Simulated Membranes. J Phys Chem B 2020; 124:6963-6971. [DOI: 10.1021/acs.jpcb.0c03937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Conner M. Winkeljohn
- Department of Physics, University of Vermont, Burlington, Vermont 05405, United States
| | - Benjamin Himberg
- Materials Science Graduate Program, University of Vermont, Burlington, Vermont 05405, United States
| | - Juan M. Vanegas
- Department of Physics, University of Vermont, Burlington, Vermont 05405, United States
- Materials Science Graduate Program, University of Vermont, Burlington, Vermont 05405, United States
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11
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Shan Y, Ji Y, Wang X, He L, Li S. Predicting asymmetric phospholipid microstructures in solutions. RSC Adv 2020; 10:24521-24532. [PMID: 35516199 PMCID: PMC9055179 DOI: 10.1039/d0ra03732j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 06/18/2020] [Indexed: 01/29/2023] Open
Abstract
Asymmetric phospholipid microstructures, such as asymmetric phospholipid membranes, have potential applications in biological and medicinal processes. Here, we used the dissipative particle dynamics simulation method to predict the asymmetric phospholipid microstructures in aqueous solutions. The asymmetric phospholipid membranes, tubes and vesicles are determined and characterized by the chain density distributions and order parameters. The phase diagrams are constructed to evaluate the effects of the chain length on the asymmetric structure formations at equilibrium states, while the average radius of gyration and shape factors are calculated to analyze the asymmetric structure formations in the non-equilibrium processes. Meanwhile, we predicted the mechanical properties of the asymmetric membranes by analyzing the spatial distributions of the interface tensions and osmotic pressures in solutions.
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Affiliation(s)
- Yue Shan
- Department of Physics, Wenzhou University Wenzhou Zhejiang 325035 China
| | - Yongyun Ji
- Department of Physics, Wenzhou University Wenzhou Zhejiang 325035 China
| | - Xianghong Wang
- Department of Physics, Wenzhou University Wenzhou Zhejiang 325035 China
| | - Linli He
- Department of Physics, Wenzhou University Wenzhou Zhejiang 325035 China
| | - Shiben Li
- Department of Physics, Wenzhou University Wenzhou Zhejiang 325035 China
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12
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Bore SL, Kolli HB, De Nicola A, Byshkin M, Kawakatsu T, Milano G, Cascella M. Hybrid particle-field molecular dynamics under constant pressure. J Chem Phys 2020; 152:184908. [PMID: 32414244 DOI: 10.1063/5.0007445] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Hybrid particle-field methods are computationally efficient approaches for modeling soft matter systems. So far, applications of these methodologies have been limited to constant volume conditions. Here, we reformulate particle-field interactions to represent systems coupled to constant external pressure. First, we show that the commonly used particle-field energy functional can be modified to model and parameterize the isotropic contributions to the pressure tensor without interfering with the microscopic forces on the particles. Second, we employ a square gradient particle-field interaction term to model non-isotropic contributions to the pressure tensor, such as in surface tension phenomena. This formulation is implemented within the hybrid particle-field molecular dynamics approach and is tested on a series of model systems. Simulations of a homogeneous water box demonstrate that it is possible to parameterize the equation of state to reproduce any target density for a given external pressure. Moreover, the same parameterization is transferable to systems of similar coarse-grained mapping resolution. Finally, we evaluate the feasibility of the proposed approach on coarse-grained models of phospholipids, finding that the term between water and the lipid hydrocarbon tails is alone sufficient to reproduce the experimental area per lipid in constant-pressure simulations and to produce a qualitatively correct lateral pressure profile.
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Affiliation(s)
- Sigbjørn Løland Bore
- Department of Chemistry, and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
| | - Hima Bindu Kolli
- Department of Chemistry, and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
| | - Antonio De Nicola
- Department of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata-ken 992-8510, Japan
| | - Maksym Byshkin
- Institute of Computational Science, Università Della Svizzera Italiana, 6900 Lugano, Switzerland
| | - Toshihiro Kawakatsu
- Department of Physics, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Giuseppe Milano
- Department of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata-ken 992-8510, Japan
| | - Michele Cascella
- Department of Chemistry, and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
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13
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Qi S, Zhou J, Schmid F. Shear Modulus of an Irreversible Diblock Copolymer Network from Self-Consistent Field Theory. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shuanhu Qi
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, China
| | - Jiajia Zhou
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, China
| | - Friederike Schmid
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
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14
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Affiliation(s)
- De-Wen Sun
- Institut für Theoretische Physik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany
| | - Marcus Müller
- Institut für Theoretische Physik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany
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15
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Sun DW, Müller M. Fabrication of Ellipsoidal Mesostructures in Block Copolymers via a Step-Shear Deformation. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b02060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- De-Wen Sun
- Institut für Theoretische
Physik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz
1, D 37077 Göttingen, Germany
| | - Marcus Müller
- Institut für Theoretische
Physik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz
1, D 37077 Göttingen, Germany
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16
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Barragán Vidal IA, Müller M. Generalization of the swelling method to measure the intrinsic curvature of lipids. J Chem Phys 2017; 147:224902. [PMID: 29246037 DOI: 10.1063/1.5001858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Via computer simulation of a coarse-grained model of two-component lipid bilayers, we compare two methods of measuring the intrinsic curvatures of the constituting monolayers. The first one is a generalization of the swelling method that, in addition to the assumption that the spontaneous curvature linearly depends on the composition of the lipid mixture, incorporates contributions from its elastic energy. The second method measures the effective curvature-composition coupling between the apposing leaflets of bilayer structures (planar bilayers or cylindrical tethers) to extract the spontaneous curvature. Our findings demonstrate that both methods yield consistent results. However, we highlight that the two-leaflet structure inherent to the latter method has the advantage of allowing measurements for mixed lipid systems up to their critical point of demixing as well as in the regime of high concentration (of either species).
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Affiliation(s)
- I A Barragán Vidal
- Institut für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - M Müller
- Institut für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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