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Kahana A, Lancet D, Palmai Z. Micellar Composition Affects Lipid Accretion Kinetics in Molecular Dynamics Simulations: Support for Lipid Network Reproduction. Life (Basel) 2022; 12:955. [PMID: 35888044 PMCID: PMC9325298 DOI: 10.3390/life12070955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/02/2022] [Accepted: 06/21/2022] [Indexed: 11/25/2022] Open
Abstract
Mixed lipid micelles were proposed to facilitate life through their documented growth dynamics and catalytic properties. Our previous research predicted that micellar self-reproduction involves catalyzed accretion of lipid molecules by the residing lipids, leading to compositional homeostasis. Here, we employ atomistic Molecular Dynamics simulations, beginning with 54 lipid monomers, tracking an entire course of micellar accretion. This was done to examine the self-assembly of variegated lipid clusters, allowing us to measure entry and exit rates of monomeric lipids into pre-micelles with different compositions and sizes. We observe considerable rate-modifications that depend on the assembly composition and scrutinize the underlying mechanisms as well as the energy contributions. Lastly, we describe the measured potential for compositional homeostasis in our simulated mixed micelles. This affirms the basis for micellar self-reproduction, with implications for the study of the origin of life.
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Affiliation(s)
| | | | - Zoltan Palmai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 761001, Israel; (A.K.); (D.L.)
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2
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Zhang X, Kindt JT. Free energy of micellization of dodecyl phosphocholine (DPC) from molecular simulation: Hybrid PEACH-BAR method. J Comput Chem 2021; 42:2221-2232. [PMID: 34561897 DOI: 10.1002/jcc.26751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/08/2021] [Accepted: 09/05/2021] [Indexed: 11/06/2022]
Abstract
A new method to extract the free energy of aggregation versus aggregate size from molecular simulation data is proposed and applied to a united atom model of the zwitterionic surfactant dodecyl phosphocholine in water. This system's slow dissociation rate and low critical micelle concentration (CMC of approximately 1-2 mM) make extraction of cluster free energies directly from simulation results using the "partition-enabled analysis of cluster histogram" (PEACH) method impractical. The new approach applies PEACH to a model with weakened attractions between aggregants, which allows sampling of a continuous range of cluster sizes, then recovers the free energy of aggregation under the original fully-attractive force field using the BAR free energy difference method. PEACH-BAR results are compared with free energy differences calculated via umbrella sampling, and are used to make predictions of CMC, average cluster size, and SAXS scattering profiles that are in fair agreement with experiment.
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Affiliation(s)
- Xiaokun Zhang
- Department of Chemistry, Emory University, Atlanta, Georgia, USA
| | - James T Kindt
- Department of Chemistry, Emory University, Atlanta, Georgia, USA
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3
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Volkov NA, Eroshkin YA, Shchekin AK, Koltsov IN, Tretyakov NY, Turnaeva EA, Volkova SS, Groman AA. Molecular Dynamics of Decane Solubilization and Diffusion of Aggregates Consisting of Surfactant and Decane Molecules in Aqueous Solutions. COLLOID JOURNAL 2021. [DOI: 10.1134/s1061933x21040141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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4
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Deaton TA, Aydin F, Li NK, Chu X, Dutt M, Yingling YG. Dissipative Particle Dynamics Approaches to Modeling the Self-Assembly and Morphology of Neutral and Ionic Block Copolymers in Solution. FOUNDATIONS OF MOLECULAR MODELING AND SIMULATION 2021. [DOI: 10.1007/978-981-33-6639-8_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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5
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Urano R, Pantelopulos GA, Straub JE. Aerosol-OT Surfactant Forms Stable Reverse Micelles in Apolar Solvent in the Absence of Water. J Phys Chem B 2019; 123:2546-2557. [PMID: 30688469 DOI: 10.1021/acs.jpcb.8b07847] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Normal micelle aggregates of amphiphilic surfactant in aqueous solvents are formed by a process of entropically driven self-assembly. The self-assembly of reverse micelles from amphiphilic surfactant in a nonpolar solvent in the presence of water is considered to be an enthalpically driven process. Although the formation of normal and reverse surfactant micelles has been well characterized in theory and experiment, the nature of dry micelle formation, from amphiphilic surfactant in a nonpolar solvent in the absence of water, is poorly understood. In this study, a theory of dry reverse micelle formation is developed. Variation in free energy during micelle assembly is derived for the specific case of aerosol-OT surfactant in isooctane solvent using atomistic molecular dynamics simulation analyzed using the energy representation method. The existence and thermodynamic stability of dry reverse micelles of limited size are confirmed. The abrupt occurrence of monodisperse aggregates is a clear signature of a critical micelle concentration, commonly observed in the formation of normal surfactant micelles. The morphology of large dry micelles provides insight into the nature of the thermodynamic driving forces stabilizing the formation of the surfactant aggregates. Overall, this study provides detailed insight into the structure and stability of dry reverse micelles assembly in a nonpolar solvent.
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Affiliation(s)
- Ryo Urano
- Chemistry Department , Boston University , 590 Commonwealth Avenue , Boston , Massachusetts 02215 , United States
| | - George A Pantelopulos
- Chemistry Department , Boston University , 590 Commonwealth Avenue , Boston , Massachusetts 02215 , United States
| | - John E Straub
- Chemistry Department , Boston University , 590 Commonwealth Avenue , Boston , Massachusetts 02215 , United States
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6
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Chen H, Panagiotopoulos AZ. Molecular Modeling of Surfactant Micellization Using Solvent-Accessible Surface Area. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2443-2450. [PMID: 30624073 DOI: 10.1021/acs.langmuir.8b03440] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report a new implicit solvent simulation model for studying the self-assembly of surfactants, where the hydrophobic interactions were captured by calculating the relative changes of the solvent-accessible surface area (SASA) of the hydrophobic domains. Using histogram-reweighting grand canonical Monte Carlo simulations, we demonstrate that this approach allows us to match both the experimental critical micelle concentrations (cmc) and micellar aggregation numbers simultaneously with a single phenomenological surface tension γSASA for the poly(oxyethylene) monoalkyl ether (C mE n) surfactants in aqueous solutions. Excellent transferability is observed: the same model can accurately predict the experimental cmc and aggregation numbers for the C mE n surfactants with the alkyl lengths m between 6 and 12 and the poly(oxyethylene) lengths n between 1 and 9. The SASA-based implicit solvent model put forward in this work is general and may be applied to study more complex amphiphilic systems such as surfactants with branched alkyl chains or surfactant-hydrocarbon mixtures.
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Affiliation(s)
- Hsieh Chen
- Aramco Services Company: Aramco Research Center-Boston , 400 Technology Square , Cambridge , Massachusetts 02139 , United States
| | - Athanassios Z Panagiotopoulos
- Department of Chemical and Biological Engineering , Princeton University , Princeton , New Jersey 08544 , United States
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7
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Volkov NA, Posysoev MV, Shchekin AK. The Effect of Simulation Cell Size on the Diffusion Coefficient of an Ionic Surfactant Aggregate. COLLOID JOURNAL 2018. [DOI: 10.1134/s1061933x1803016x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Adzhemyan LV, Kim TL, Shchekin AK. The Stage of Ultrafast Relaxation in Micellar Surfactant Solutions. COLLOID JOURNAL 2018. [DOI: 10.1134/s1061933x1803002x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Shchekin AK, Adzhemyan LT, Babintsev IA, Volkov NA. Kinetics of Aggregation and Relaxation in Micellar Surfactant Solutions. COLLOID JOURNAL 2018. [DOI: 10.1134/s1061933x18020084] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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10
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Zhang X, Patel LA, Beckwith O, Schneider R, Weeden CJ, Kindt JT. Extracting Aggregation Free Energies of Mixed Clusters from Simulations of Small Systems: Application to Ionic Surfactant Micelles. J Chem Theory Comput 2017; 13:5195-5206. [PMID: 28942641 DOI: 10.1021/acs.jctc.7b00671] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Micelle cluster distributions from molecular dynamics simulations of a solvent-free coarse-grained model of sodium octyl sulfate (SOS) were analyzed using an improved method to extract equilibrium association constants from small-system simulations containing one or two micelle clusters at equilibrium with free surfactants and counterions. The statistical-thermodynamic and mathematical foundations of this partition-enabled analysis of cluster histograms (PEACH) approach are presented. A dramatic reduction in computational time for analysis was achieved through a strategy similar to the selector variable method to circumvent the need for exhaustive enumeration of the possible partitions of surfactants and counterions into clusters. Using statistics from a set of small-system (up to 60 SOS molecules) simulations as input, equilibrium association constants for micelle clusters were obtained as a function of both number of surfactants and number of associated counterions through a global fitting procedure. The resulting free energies were able to accurately predict micelle size and charge distributions in a large (560 molecule) system. The evolution of micelle size and charge with SOS concentration as predicted by the PEACH-derived free energies and by a phenomenological four-parameter model fit, along with the sensitivity of these predictions to variations in cluster definitions, are analyzed and discussed.
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Affiliation(s)
- X Zhang
- Department of Chemistry and ‡Department of Mathematics and Computer Science, Emory University , Atlanta, Georgia 30322, United States
| | - L A Patel
- Department of Chemistry and ‡Department of Mathematics and Computer Science, Emory University , Atlanta, Georgia 30322, United States
| | - O Beckwith
- Department of Chemistry and ‡Department of Mathematics and Computer Science, Emory University , Atlanta, Georgia 30322, United States
| | - R Schneider
- Department of Chemistry and ‡Department of Mathematics and Computer Science, Emory University , Atlanta, Georgia 30322, United States
| | - C J Weeden
- Department of Chemistry and ‡Department of Mathematics and Computer Science, Emory University , Atlanta, Georgia 30322, United States
| | - J T Kindt
- Department of Chemistry and ‡Department of Mathematics and Computer Science, Emory University , Atlanta, Georgia 30322, United States
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11
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García Daza FA, Bonet Avalos J, Mackie AD. Logarithmic Exchange Kinetics in Monodisperse Copolymeric Micelles. PHYSICAL REVIEW LETTERS 2017; 118:248001. [PMID: 28665650 DOI: 10.1103/physrevlett.118.248001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Indexed: 06/07/2023]
Abstract
Experimental measurements of the relaxation kinetics of copolymeric surfactant exchange for micellar systems unexpectedly show a peculiar logarithmic decay. Several authors use polydispersity as an explanation for this behavior. However, in coarse-grained simulations that preserve microscopic details of the surfactants, we find evidence of the same logarithmic behavior. Since we use a strictly monodisperse distribution of chain lengths such a relaxation process cannot be attributed to polydispersity, but has to be caused by an inherent physical process characteristic of this type of system. This is supported by the fact that the decay is specifically logarithmic and not a power law with an exponent inherited from the particular polydispersity distribution of the sample. We suggest that the degeneracy of the energy states of the hydrophobic block in the core, which is broken on leaving the micelle, can qualitatively explain the broad distribution of energy barriers, which gives rise to the observed nonexponential relaxation.
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Affiliation(s)
- Fabián A García Daza
- Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans 26, 43007 Tarragona, Spain
| | - Josep Bonet Avalos
- Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans 26, 43007 Tarragona, Spain
| | - Allan D Mackie
- Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans 26, 43007 Tarragona, Spain
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12
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13
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Volkov NA, Tuzov NV, Shchekin AK. All-atom molecular dynamics analysis of kinetic and structural properties of ionic micellar solutions. COLLOID JOURNAL 2017. [DOI: 10.1134/s1061933x17020156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Rodgers TL, Magee JE, Amure T, Siperstein FR. Micelle response to changes in solvent properties. SOFT MATTER 2016; 12:9014-9024. [PMID: 27782285 DOI: 10.1039/c6sm01761d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The dynamics of co-polymer systems play an important role in the preparation and stability of formulations, as well as on their capability to function in drug delivery systems. Micelle inversion can occur as a result of a change in concentration when a solvent is very volatile and evaporates, or as a result of a change in solvent quality upon addition of another solvent to the original solution, or upon changes in pH. In this work, dissipative particle dynamics (DPD) is used to examine the dynamics of micelle inversion in concentrated systems of diblock and triblock amphiphiles, where interactions between neighboring aggregates are observed. Significant differences were observed in the inversion process of different amphiphilic molecules, with a large amount of co-polymer exchange between inverting aggregates made of diblock amphiphiles, and practically no exchange of molecules between aggregates during the inversion of triblock copolymer aggregates. Fundamental mechanisms of inversion are revealed that provide information which can be used to help design micelles for targeted drug release and allow understanding of history dependant formulations.
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Affiliation(s)
- T L Rodgers
- SCEAS, The University of Manchester, Manchester M13 9PL, UK.
| | - J E Magee
- SCEAS, The University of Manchester, Manchester M13 9PL, UK.
| | - T Amure
- SCEAS, The University of Manchester, Manchester M13 9PL, UK.
| | - F R Siperstein
- SCEAS, The University of Manchester, Manchester M13 9PL, UK.
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15
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Shchekin AK, Babintsev IA, Adzhemyan LT. Full-time kinetics of self-assembly and disassembly in micellar solution via the generalized Smoluchowski equation with fusion and fission of surfactant aggregates. J Chem Phys 2016; 145:174105. [DOI: 10.1063/1.4966233] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alexander K. Shchekin
- Department of Statistical Physics, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Ilya A. Babintsev
- Department of Statistical Physics, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Loran Ts. Adzhemyan
- Department of Statistical Physics, St. Petersburg State University, St. Petersburg 199034, Russia
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16
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Vila Verde A, Frenkel D. Kinetics of formation of bile salt micelles from coarse-grained Langevin dynamics simulations. SOFT MATTER 2016; 12:5172-5179. [PMID: 27199094 DOI: 10.1039/c6sm00763e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We examine the mechanism of formation of micelles of dihydroxy bile salts using a coarse-grained, implicit solvent model and Langevin dynamics simulations. We find that bile salt micelles primarily form via addition and removal of monomers, similarly to surfactants with typical head-tail molecular structures, and not via a two-stage mechanism - involving formation of oligomers and their subsequent aggregation to form larger micelles - originally proposed for bile salts. The free energy barrier to removal of single bile monomers from micelles is ≈2kBT, much less than what has been observed for head-tail surfactants. Such a low barrier may be biologically relevant: it allows for rapid release of bile monomers into the intestine, possibly enabling the coverage of fat droplets by bile salt monomers and subsequent release of micelles containing fats and bile salts - a mechanism that is not possible for ionic head-tail surfactants of similar critical micellar concentrations.
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Affiliation(s)
- Ana Vila Verde
- Theory and Bio-Systems Department, Max Planck Institute of Colloids and Interfaces, Wissenschaftspark Golm, 14424 Potsdam, Germany.
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17
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Zakharov AI, Adzhemyan LT, Shchekin AK. Relaxation times and modes of disturbed aggregate distribution in micellar solutions with fusion and fission of micelles. J Chem Phys 2015; 143:124902. [DOI: 10.1063/1.4931413] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Anatoly I. Zakharov
- Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russian Federation
| | - Loran Ts. Adzhemyan
- Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russian Federation
| | - Alexander K. Shchekin
- Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russian Federation
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18
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Modelling the interfacial behaviour of dilute light-switching surfactant solutions. J Colloid Interface Sci 2015; 445:16-23. [DOI: 10.1016/j.jcis.2014.12.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/07/2014] [Accepted: 12/10/2014] [Indexed: 11/17/2022]
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19
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Nevidimov AV. Molecular dynamics simulation of reverse micelles: Standing problems after 25 years of research. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2014. [DOI: 10.1134/s199079311404023x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Babintsev IA, Adzhemyan LT, Shchekin AK. Multi-scale times and modes of fast and slow relaxation in solutions with coexisting spherical and cylindrical micelles according to the difference Becker-Döring kinetic equations. J Chem Phys 2014; 141:064901. [PMID: 25134593 DOI: 10.1063/1.4890531] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The eigenvalues and eigenvectors of the matrix of coefficients of the linearized kinetic equations applied to aggregation in surfactant solution determine the full spectrum of characteristic times and specific modes of micellar relaxation. The dependence of these relaxation times and modes on the total surfactant concentration has been analyzed for concentrations in the vicinity and well above the second critical micelle concentration (cmc2) for systems with coexisting spherical and cylindrical micelles. The analysis has been done on the basis of a discrete form of the Becker-Döring kinetic equations employing the Smoluchowsky diffusion model for the attachment rates of surfactant monomers to surfactant aggregates with matching the rates for spherical aggregates and the rates for large cylindrical micelles. The equilibrium distribution of surfactant aggregates in solution has been modeled as having one maximum for monomers, another maximum for spherical micelles and wide slowly descending branch for cylindrical micelles. The results of computations have been compared with the analytical ones known in the limiting cases from solutions of the continuous Becker-Döring kinetic equation. They demonstrated a fair agreement even in the vicinity of the cmc2 where the analytical theory looses formally its applicability.
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Affiliation(s)
- Ilya A Babintsev
- Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russian Federation
| | - Loran Ts Adzhemyan
- Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russian Federation
| | - Alexander K Shchekin
- Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russian Federation
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21
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Rissanou AN, Tzeli DS, Anastasiadis SH, Bitsanis IA. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study. J Chem Phys 2014; 140:204904. [DOI: 10.1063/1.4875694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Shchekin AK, Babintsev IA, Adzhemyan LT, Volkov NA. Kinetic modeling of self-aggregation in solutions with coexisting spherical and cylindrical micelles at arbitrary initial conditions. RSC Adv 2014. [DOI: 10.1039/c4ra08683j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The whole picture of evolution of coexisting spherical and cylindrical micelles has been described for initial states far from equilibrium.
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Affiliation(s)
- A. K. Shchekin
- Department of Statistical Physics
- Faculty of Physics
- St Petersburg State University
- St Petersburg, Russian Federation
| | - I. A. Babintsev
- Department of Statistical Physics
- Faculty of Physics
- St Petersburg State University
- St Petersburg, Russian Federation
| | - L. Ts. Adzhemyan
- Department of Statistical Physics
- Faculty of Physics
- St Petersburg State University
- St Petersburg, Russian Federation
| | - N. A. Volkov
- Department of Statistical Physics
- Faculty of Physics
- St Petersburg State University
- St Petersburg, Russian Federation
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23
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Jensen GV, Lund R, Gummel J, Monkenbusch M, Narayanan T, Pedersen JS. Direct observation of the formation of surfactant micelles under nonisothermal conditions by synchrotron SAXS. J Am Chem Soc 2013; 135:7214-22. [PMID: 23590205 DOI: 10.1021/ja312469n] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Self-assembly of amphiphilic molecules into micelles occurs on very short times scales of typically some milliseconds, and the structural evolution is therefore very challenging to observe experimentally. While rate constants of surfactant micelle kinetics have been accessed by spectroscopic techniques for decades, so far no experiments providing detailed information on the structural evolution of surfactant micelles during their formation process have been reported. In this work we show that by applying synchrotron small-angle X-ray scattering (SAXS) in combination with the stopped-flow mixing technique, the entire micelle formation process from single surfactants to equilibrium micelles can be followed in situ. Using a sugar-based surfactant system of dodecyl maltoside (DDM) in dimethylformamide (DMF), micelle formation can be induced simply by adding water, and this can be followed in situ by SAXS. Mixing of water and DMF is an exothermic process where the micelle formation process occurs under nonisothermal conditions with a temperature gradient relaxing from about 40 to 20 °C. A kinetic nucleation and growth mechanism model describing micelle formation by insertion/expulsion of single molecules under nonisothermal conditions was developed and shown to describe the data very well.
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Affiliation(s)
- Grethe Vestergaard Jensen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark.
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24
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Bhattacharjee JK, Kaatze U. Fluctuations Near the Critical Micelle Concentration. I. Premicellar Aggregation, Relaxation Rate, and Isentropic Compressibility. J Phys Chem B 2013; 117:3790-7. [DOI: 10.1021/jp4011185] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Udo Kaatze
- Drittes Physikalisches
Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz
1, 37077 Göttingen, Germany
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25
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Gai L, Maerzke K, Cummings PT, McCabe C. A Wang-Landau study of a lattice model for lipid bilayer self-assembly. J Chem Phys 2013; 137:144901. [PMID: 23061859 DOI: 10.1063/1.4754536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Wang-Landau (WL) Monte Carlo method has been applied to simulate the self-assembly of a lipid bilayer on a 3D lattice. The WL method differs from conventional Monte Carlo methods in that a complete density of states is obtained directly for the system, from which properties, such as the free energy, can be derived. Furthermore, from a single WL simulation, continuous curves of the average energy and heat capacity can be determined, which provide a complete picture of the phase behavior. The lipid model studied consists of 3 or 5 coarse-grained segments on lattices of varying sizes, with the empty lattice sites representing water. A bilayer structure is found to form at low temperatures, with phase transitions to clusters as temperature increases. For 3-segment chains, varying lattice sizes were studied, with the observation that the ratio of chain number to lattice area (i.e., area per lipid) affects the phase transition temperature. At small ratios, only one phase transition occurs between the bilayer and cluster phases, while at high lipid ratios the phase transition occurs in a two-step process with a stable intermediate phase. This second phase transition was not observed in conventional Metropolis Monte Carlo simulations on the same model, demonstrating the advantage of being able to perform a complete scan of the whole temperature range with the WL method. For longer 5-segment chains similar phase transitions are also observed with changes in temperature. In the WL method, due to the extensive nature of the energy, the number of energy bins required to represent the density of states increases as the system size increases and so limits its practical application to larger systems. To improve this, an extension of the WL algorithm, the statistical-temperature Monte Carlo method that allows simulations with larger energy bin sizes, has recently been proposed and is implemented in this work for the 3-segment lattice model. The results obtained are in good agreement with the original WL method and appear to be independent of the energy bin size used.
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Affiliation(s)
- Lili Gai
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
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26
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Kindt JT. Accounting for Finite-Number Effects on Cluster Size Distributions in Simulations of Equilibrium Aggregation. J Chem Theory Comput 2012; 9:147-52. [DOI: 10.1021/ct300686u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- James T. Kindt
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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27
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Ahn YN, Mohan G, Kopelevich DI. Collective degrees of freedom involved in absorption and desorption of surfactant molecules in spherical non-ionic micelles. J Chem Phys 2012; 137:164902. [DOI: 10.1063/1.4762816] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Babintsev I, Adzhemyan L, Shchekin A. Micellization and relaxation in solution with spherical micelles via the discrete Becker–Döring equations at different total surfactant concentrations. J Chem Phys 2012; 137:044902. [DOI: 10.1063/1.4737130] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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29
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30
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Griffiths IM, Bain CD, Breward CJW, Colegate DM, Howell PD, Waters SL. On the predictions and limitations of the Becker–Döring model for reaction kinetics in micellar surfactant solutions. J Colloid Interface Sci 2011; 360:662-71. [DOI: 10.1016/j.jcis.2011.04.074] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/14/2011] [Accepted: 04/19/2011] [Indexed: 11/30/2022]
Affiliation(s)
- I M Griffiths
- Mathematical Institute, University of Oxford, OX1 3LB, UK.
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31
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Ahn YN, Gupta A, Chauhan A, Kopelevich DI. Molecular transport through surfactant-covered oil-water interfaces: role of physical properties of solutes and surfactants in creating energy barriers for transport. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2420-2436. [PMID: 21309583 DOI: 10.1021/la103550v] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Mechanisms of molecular transport across oil-water interfaces covered by nonionic surfactants are investigated using coarse-grained molecular dynamics simulations. Resistance of the surfactant monolayer to the solute transport is shown to be controlled by dense regions in the monolayer. The dense regions are formed on both sides of the dividing surface and the barrier to the solute transport is created by those of them experiencing unfavorable interactions with the solute. Resistance to the transport of a hydrophobic (hydrophilic) solute increases with the excess density of the head (tail) group region of the monolayer, which in turn increases with the length of the surfactant head (tail) group. Barriers for solute transport through surfactant monolayers are also influenced by the solute size. However, the extent of this influence is determined by the monolayer thickness and the solute structure and composition. For example, it is shown that resistance offered by thin monolayers to transport of linear oligomers is relatively insensitive to the solute length. The barrier sensitivity to the length of these solutes increases with the monolayer thickness. In addition to the static barriers, the solute transport is shown to be affected by dynamic barriers due to a nonadiabatic coupling of the monolayer surface with the solute position and configuration. This coupling leads to deviations of the system dynamics from the minimum energy path. The deviations are most significant in the neighborhood of the static energy barrier, which effectively leads to an increase of the barrier for the solute transport.
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Affiliation(s)
- Yong Nam Ahn
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, United States
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32
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Jusufi A, Sanders S, Klein ML, Panagiotopoulos AZ. Implicit-Solvent Models for Micellization: Nonionic Surfactants and Temperature-Dependent Properties. J Phys Chem B 2011; 115:990-1001. [DOI: 10.1021/jp108107f] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Arben Jusufi
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Samantha Sanders
- Department of Chemical and Biological Engineering and Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
| | - Michael L. Klein
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Athanassios Z. Panagiotopoulos
- Department of Chemical and Biological Engineering and Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
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33
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Hadgiivanova R, Diamant H, Andelman D. Kinetics of Surfactant Micellization: A Free Energy Approach. J Phys Chem B 2010; 115:7268-80. [DOI: 10.1021/jp1073335] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Radina Hadgiivanova
- Raymond and Beverly Sackler School of Chemistry and ‡Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Haim Diamant
- Raymond and Beverly Sackler School of Chemistry and ‡Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - David Andelman
- Raymond and Beverly Sackler School of Chemistry and ‡Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
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34
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de Moraes J, Figueiredo W. Temporal evolution of micellar aggregates in the temperature jump experiments. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.03.070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Sanders SA, Panagiotopoulos AZ. Micellization behavior of coarse grained surfactant models. J Chem Phys 2010; 132:114902. [DOI: 10.1063/1.3358354] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Heinzelmann G, Figueiredo W, Girardi M. Interplay between micelle formation and waterlike phase transitions. J Chem Phys 2010; 132:064905. [DOI: 10.1063/1.3316133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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37
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Heinzelmann G, Figueiredo W, Girardi M. Monte Carlo simulations for amphiphilic aggregation near a water phase transition. J Chem Phys 2009; 131:144901. [DOI: 10.1063/1.3244676] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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38
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Burov SV, Vanin AA, Brodskaya EN. Principal role of the stepwise aggregation mechanism in ionic surfactant solutions near the critical micelle concentration. Molecular dynamics study. J Phys Chem B 2009; 113:10715-20. [PMID: 19591445 DOI: 10.1021/jp9025305] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The validity of the assumption on the predominant contribution of the stepwise processes to the ionic micelle formation/destruction in the vicinity of critical micelle concentration was investigated by molecular dynamics simulation. A coarse-grained model was used to describe the surfactant/water mixture. The cluster size distribution was estimated directly from molecular dynamics simulations or obtained from a reduced set of kinetic equations. The good agreement between two approaches shows that the neglect of the terms responsible for cluster fusion/fission is fully justified and that such processes are less important than stepwise aggregation.
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Affiliation(s)
- Stanislav V Burov
- Department of Chemistry, Saint Petersburg State University, Universitetskiy pr. 26, Stariy Petergof, Saint Petersburg 198504, Russia.
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39
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Fujiwara S, Itoh T, Hashimoto M, Horiuchi R. Molecular dynamics simulation of amphiphilic molecules in solution: Micelle formation and dynamic coexistence. J Chem Phys 2009; 130:144901. [DOI: 10.1063/1.3105341] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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40
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FUJIWARA S, HASHIMOTO M, ITOH T. Molecular Dynamics Simulations for Structure Formation of Polymers and Self-Assembly of Amphiphilic Molecules. KOBUNSHI RONBUNSHU 2009. [DOI: 10.1295/koron.66.396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Susumu FUJIWARA
- Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology
| | - Masato HASHIMOTO
- Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology
| | - Takashi ITOH
- Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology
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41
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Gupta A, Chauhan A, Kopelevich DI. Molecular transport across fluid interfaces: coupling between solute dynamics and interface fluctuations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:041605. [PMID: 18999437 DOI: 10.1103/physreve.78.041605] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Indexed: 05/27/2023]
Abstract
We investigate the transport mechanism of a small hydrophobic solute molecule across two types of fluid interfaces, (i) an interface between two immiscible liquids and (ii) a surfactant-covered liquid-liquid interface. These systems are modeled by coarse-grained molecular dynamics simulations. It is demonstrated that the dynamics of the solute molecule near the interface significantly deviates from Markovian Brownian motion. Specifically, the correlation time of the random force acting on the solute strongly depends on the distance between the solute and the interface and increases by two orders of magnitude within a very narrow (less than 1 nm wide) region near the interface. The slow fluctuations of the random force in this narrow region are caused by capillary waves. The region location and width are determined by interface protrusions caused by attraction between the solute and the hydrophobic phase. We use results of molecular dynamics simulations to develop a stochastic model for the coupled solute-interface dynamics and estimate the rate of the solute transport across the interface. The observed phenomenon appears to be a general feature of mass transport across fluid or flexible membranes. The coupling between the solute transport and the interface fluctuations is the strongest in areas corresponding to a large free energy gradient or near a free energy barrier for the solute transport. This suggests a strong influence of the coupled solute-interface dynamics on the rate of mass transfer across interfaces.
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Affiliation(s)
- Ashish Gupta
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611-6005, USA
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42
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Studying the unfolding kinetics of proteins under pressure using long molecular dynamic simulation runs. J Biol Phys 2008; 33:515-22. [PMID: 19669536 DOI: 10.1007/s10867-008-9083-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Accepted: 04/22/2008] [Indexed: 11/27/2022] Open
Abstract
The usefulness of computational methods such as molecular dynamics simulation has been extensively established for studying systems in equilibrium. Nevertheless, its application to complex non-equilibrium biological processes such as protein unfolding has been generally regarded as producing results which cannot be interpreted straightforwardly. In the present study, we present results for the kinetics of unfolding of apomyoglobin, based on the analysis of long simulation runs of this protein in solution at 3 kbar (1 atm = 1.01325, bar = 101,325 Pa). We hereby demonstrate that the analysis of the data collected within a simulated time span of 0.18 mus suffices for producing results, which coincide remarkably with the available unfolding kinetics experimental data. This not only validates molecular dynamics simulation as a valuable alternative for studying non-equilibrium processes, but also enables a detailed analysis of the actual structural mechanism which underlies the unfolding process of proteins under elusive denaturing conditions such as high pressure.
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