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Chen Q, Zheng J. Self-assembly and structures of nanoscale double emulsion droplets through coarse-grained molecular dynamics simulations. SOFT MATTER 2023; 19:7731-7743. [PMID: 37789812 DOI: 10.1039/d3sm00656e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Examples of self-assembled multiple emulsion droplets on the nanometre scale are very rare. In this work, we use coarse-grained (CG) molecular dynamics simulations to study the self-assembly of ternary mixtures consisting of water, n-heptane, and nonionic surfactant tetraethylene glycol monododecyl ether (C12E4). The water volume fractions studied are 1%, 3%, and 5%, respectively. Various nanoscale emulsions are obtained in a spontaneous process. When the water/surfactant volume ratio vm/s = 1.0/1.0, the obtained emulsion droplets are identified as oil-in-water-in-oil (O/W/O) double types, consisting of an oil core, an inner surfactant layer, a water layer, and an outer surfactant layer. The water molecules are distributed around the hydrophilic ends of the surfactants, while the hydrophobic ends of the surfactants wrap the oil cores and penetrate into the oil bulk. Hydrogen-bond interactions among water and the hydrophilic ends of the surfactants form cross-links that stabilize the double emulsion droplets. The sizes of all the oil cores inside the droplets are <6 nm in diameter, even with the highest water volume fraction of 5%. Both the concentration of free water molecules on the order of 10-6 mol/cm3 and the favourable energy change during emulsion formation indicate that the emulsion droplets are thermodynamically stable. In contrast, for vm/s = 1.0/5.5, no double emulsion but a simple water-in-oil emulsion was observed, with morphologies evolving from oblate to bicontinuous phases with an increase in the water volume fraction from 1% to 5%. Our coarse-grained molecular dynamics simulations provide valuable insight for the preparation of nanoscale double emulsions and the characterization of their structures.
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Affiliation(s)
- Qiubo Chen
- Institute of High Performance Computing (IHPC), Agency for Science, Technology and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore.
| | - Jianwei Zheng
- Institute of High Performance Computing (IHPC), Agency for Science, Technology and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore.
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2
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Dinache A, Pascu ML, Smarandache A. Spectral Properties of Foams and Emulsions. Molecules 2021; 26:7704. [PMID: 34946785 PMCID: PMC8707813 DOI: 10.3390/molecules26247704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/17/2022] Open
Abstract
The optical and spectral properties of foams and emulsions provide information about their micro-/nanostructures, chemical and time stability and molecular data of their components. Foams and emulsions are collections of different kinds of bubbles or drops with particular properties. A summary of various surfactant and emulsifier types is performed here, as well as an overview of methods for producing foams and emulsions. Absorption, reflectance, and vibrational spectroscopy (Fourier Transform Infrared spectroscopy-FTIR, Raman spectroscopy) studies are detailed in connection with the spectral characterization techniques of colloidal systems. Diffusing Wave Spectroscopy (DWS) data for foams and emulsions are likewise introduced. The utility of spectroscopic approaches has grown as processing power and analysis capabilities have improved. In addition, lasers offer advantages due to the specific properties of the emitted beams which allow focusing on very small volumes and enable accurate, fast, and high spatial resolution sample characterization. Emulsions and foams provide exceptional sensitive bases for measuring low concentrations of molecules down to the level of traces using spectroscopy techniques, thus opening new horizons in microfluidics.
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Affiliation(s)
- Andra Dinache
- National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (A.D.); (M.-L.P.)
| | - Mihail-Lucian Pascu
- National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (A.D.); (M.-L.P.)
- Faculty of Physics, University of Bucharest, 077125 Magurele, Ilfov, Romania
| | - Adriana Smarandache
- National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (A.D.); (M.-L.P.)
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3
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Molecular brushes based on copolymers of alkoxy oligo(ethylene glycol) methacrylates and dodecyl(meth)acrylate: features of synthesis by conventional free radical polymerization. Polym Bull (Berl) 2021. [DOI: 10.1007/s00289-020-03390-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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4
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Evaluation of critical packing parameter in the series of polytyrosine-PEG amphiphilic copolymers. Colloid Polym Sci 2021. [DOI: 10.1007/s00396-021-04853-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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5
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Guruge AG, Warren DB, Benameur H, Pouton CW, Chalmers DK. Aqueous phase behavior of the PEO-containing non-ionic surfactant C 12E 6: A molecular dynamics simulation study. J Colloid Interface Sci 2021; 588:257-268. [PMID: 33388586 DOI: 10.1016/j.jcis.2020.12.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 10/22/2022]
Abstract
HYPOTHESIS Non-ionic surfactants containing polyethylene oxide (PEO) chains are widely used in drug formulations, cosmetics, paints, textiles and detergents. High quality molecular dynamics models for PEO surfactants can give us detailed, atomic-scale information about the behavior of surfactant/water mixtures. SIMULATIONS We used two molecular dynamics force fields (FFs), 2016H66 and 53A6DBW, to model the simple non-ionic PEO surfactant, hexaoxyethylene dodecyl ether (C12E6). We investigated surfactant/water mixtures that span the phase diagram of starting from randomly distributed arrangements. In some cases, we also started with prebuilt, approximate models. The simulations results were compared with the experimentally observed phase behavior. FINDINGS Overall, this study shows that the spontaneous self-assembly of PEO non-ionic surfactants into different colloidal structures can be accurately modeled with MD simulations using the 2016H66 FF although transitions to well-formed hexagonal phase are slow. Of the two FFs investigated, the 2016H66 FF better reproduces the experimental phase behavior across all regions of the C12E6/water phase diagram.
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Affiliation(s)
- Amali G Guruge
- Medicinal Chemistry Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Dallas B Warren
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Hassan Benameur
- Oral Drug Delivery Innovation, Chemical Division, Lonza, Strasbourg, France
| | - Colin W Pouton
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - David K Chalmers
- Medicinal Chemistry Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
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6
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Kunche L, Natarajan U. Structure and dynamics of an aqueous solution containing poly-(acrylic acid) and non-ionic surfactant octaethylene glycol n-decyl ether (C 10E 8) aggregates and their complexes investigated by molecular dynamics simulations. SOFT MATTER 2021; 17:670-687. [PMID: 33215624 DOI: 10.1039/d0sm01322f] [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
A detailed molecular dynamics simulation study of the self-assembly, intermolecular structure and thermodynamic behavior of an aqueous solution of non-ionic surfactant octa ethylene glycol n-decyl ether (C10E8) in the presence of a non-ionic polar polymer poly(acrylic acid) PAA is presented. The aggregation number Nagg and concentration of surfactant Cs in the simulation systems were varied in the range 0.01-0.32 M and 5 < Nagg < 101 (dilute to concentrated) with a dilute polymer concentration (Cp = 0.01 M). Lamellar aggregates of non-ionic surfactant in bulk aqueous solution are shown by molecular level computations for the first time. Spherical micellar aggregates and lamellar aggregates are formed at low and high Nagg, respectively. The transition from the spherical micelle phase to the lamellar phase in a binary solution is captured for the first time. A conformational transition from coiled to extended PAA chains adsorbed on the surfactant aggregate occurs at a particular value of Nagg, commensurate with the transition from spherical micelle aggregates to anisotropic lamellar aggregates. Formation of the surfactant aggregate in binary and ternary solutions and the polymer-surfactant complex in a ternary solution is enthalpically favored. Adsorption of PAA on the surfactant aggregate surface is driven by hydrogen bonds (HBs) between carboxylic acid groups of PAA and ethylene oxide groups of C10E8. A significant number of HBs occur between polar oxygens of C10E8 and hydroxyl oxygens of PAA. The results are in agreement with the limited available experimental data on this system.
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Affiliation(s)
- Lakshmikumar Kunche
- Macromolecular Modeling and Simulation Lab, Department of Chemical Engineering, Indian Institute of Technology (IIT) Madras, Chennai 600036, India.
| | - Upendra Natarajan
- Macromolecular Modeling and Simulation Lab, Department of Chemical Engineering, Indian Institute of Technology (IIT) Madras, Chennai 600036, India.
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7
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Zakaria J, Rizal Abd Shukor S, Abd Razak K. Intermolecular Interaction of Tween 80, Water and Butanol in Micelles Formation via Molecular Dynamics Simulation. IOP CONFERENCE SERIES: MATERIALS SCIENCE AND ENGINEERING 2020; 778:012091. [DOI: 10.1088/1757-899x/778/1/012091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Abstract
Micelles entrapment approach is one of the methods to synthesize silica nanoparticles as carriers for drug delivery system. This method is useful in enhancing drug solubility, extend the circulation of blood half-life and possesses lower toxicity. The shape and size of the silica nanoparticles could be excellently controlled by manipulating the parameters such as the concentration of surfactants and composition during the synthesis process. In this study, water and butanol have been used as solvent and co-solvent, while Tween 80 has been used as the surfactant. The structural properties of the micellar system from binary (water and Tween 80) and ternary (water, Tween 80 and butanol) were reported in terms of radial distribution function (RDF) and radius of gyration (Rg). The molecular dynamics simulations were performed using Material Studio by applying COMPASS Force Field in the Forcite Module. The simulation box was created by using Amorphous Cell Module. Initially, the simulation for both system was executed under a constant number of moles, volume and energy (NVE) ensemble for 200 ps and followed by a constant number of moles, pressure and temperature (NPT) ensemble for 2000 ps. From RDF analysis, both systems have the same distance of 0.97Å, but different value of g(r) intensity, 12 and 6.35 respectively. Meanwhile, the Rg result shows a higher value in ternary systems compared to the binary system. These findings revealed that the presence of butanol would weaken the intermolecular interaction of hydrogen bond and increase the size of the micelle and consequently will affect the size of nanoparticles.
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8
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Kurtanidze M, Mzareulishvili N, Rukhadze M, Alexishvili M, Bezarashvili G, Sigua K. Study of Structure of Water Droplets of Nonionic Polyoxyethylene (4) Lauryl Ether Reverse Micelles in the Presence of Sodium Cholate. TENSIDE SURFACT DET 2020. [DOI: 10.3139/113.110673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
The microenvironment of water droplets of nonionic polyoxyethylene (4) lauryl ether reverse micelles was investigated with infrared and ultraviolet-visible spectroscopy, also by viscosity and dynamic light scattering measurements in the presence of biological surfactant sodium cholate as additive. Influence of concentrations of polyoxyethylene (4) lauryl ether and sodium cholate on the microstructure of mixed reverse micelles was studied. Influence of sodium cholate as additive on the ratio of free, bound and trapped water fractions was studied via deconvolution of the O-H stretching vibrational absorption spectra in the region of 3 000–3 800 cm−1 into three subpeaks with a Monte Carlo method. Several characteristic parameters of reverse microemulsions were calculated on the basis of measurements of their kinematic viscosity. A different influence of concentration of sodium cholate on the binding constant and association degree of optical probes (o-nitroaniline and methyl orange respectively) to ethylene oxide groups of nonionic surfactant was observed. It was found that the bound water fraction, the binding constants and association degrees, the relative density of water pockets, etc. change their values passing through an extremum under the influence of sodium cholate.
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Affiliation(s)
- Manoni Kurtanidze
- Faculty of Exact and Natural Sciences , Ivane Javakhishvili Tbilisi State University, 3 I. Chavchavadze ave, Tbilisi, 0179 , Georgia
| | - Natia Mzareulishvili
- Faculty of Exact and Natural Sciences , Ivane Javakhishvili Tbilisi State University, 3 I. Chavchavadze ave, Tbilisi, 0179 , Georgia
| | - Marina Rukhadze
- Faculty of Exact and Natural Sciences , Ivane Javakhishvili Tbilisi State University, 3 I. Chavchavadze ave, Tbilisi, 0179 , Georgia
| | - Maka Alexishvili
- Department of Chemistry , Tbilisi State Medical University, 33,Vazha Pshavela ave, Tbilisi, 0166 , Georgia
| | - George Bezarashvili
- Faculty of Exact and Natural Sciences , Ivane Javakhishvili Tbilisi State University, 3 I. Chavchavadze ave, Tbilisi, 0179 , Georgia
| | - Ketevan Sigua
- Andronikashvili Institute of Physics , I. Javakhishvili Tbilisi State University, 6 Tamarashvili Str., Tbilisi 0177 , Georgia
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9
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de Souza RM, Ratochinski RH, Karttunen M, Dias LG. Self-Assembly of Phosphocholine Derivatives Using the ELBA Coarse-Grained Model: Micelles, Bicelles, and Reverse Micelles. J Chem Inf Model 2020; 60:522-536. [PMID: 31714768 DOI: 10.1021/acs.jcim.9b00790] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The ELBA coarse-grained force field was originally developed for lipids, and its water model is described as a single-site Lennard-Jones particle with electrostatics modeled by an embedded point-dipole, while other molecules in this force field have a three (or four)-to-one mapping scheme. Here, ELBA was applied to investigate the self-assembly processes of dodecyl-phosphocholine (DPC) micelle, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dihexaoyl-sn-glycero-3-phosphocholine (DPPC/DHPC) bicelles, and DPPC/cyclohexane/water reverse micelles through coarse-grained molecular dynamics (MD) simulations. New parameters were obtained using a simplex algorithm-based calibration procedure to determine the Lennard-Jones parameters for cyclohexane, dodecane, and cyclohexane-dodecane cross-interactions. Density, self-diffusion coefficient, surface tension, and mixture excess volume were found to be in fair agreement with experimental data. These new parameters were used in the simulations, and the obtained structures were analyzed for shape, size, volume, and surface area. Except for the shape of DPC micelles, all other properties match well with available experimental data and all-atom simulations. Remarkably, in agreement with experiments the rodlike shape of the DPPC reverse micelle is well described by ELBA, while all-atom data in the literature predicts a disclike shape. To further check the consistency of the force field in reproducing the correct shapes of reverse micelles, additional simulations were performed doubling the system size. Two distinct reverse micelles were obtained both presenting the rodlike shape and correct aggregation number.
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Affiliation(s)
- R M de Souza
- Department of Chemistry , The University of Western Ontario , London , Ontario , Canada N6A 3K7.,Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil.,The Center for Advanced Materials and Biomaterials Research , The University of Western Ontario , London , Ontario , Canada N6K 3K7
| | - R H Ratochinski
- Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil
| | - Mikko Karttunen
- Department of Chemistry , The University of Western Ontario , London , Ontario , Canada N6A 3K7.,The Center for Advanced Materials and Biomaterials Research , The University of Western Ontario , London , Ontario , Canada N6K 3K7.,Department of Applied Mathematics , The University of Western Ontario , London , Ontario , Canada N6A 5B7
| | - L G Dias
- Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil
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10
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Kopanichuk IV, Vedenchuk EA, Koneva AS, Vanin AA. Structural Properties of Span 80/Tween 80 Reverse Micelles by Molecular Dynamics Simulations. J Phys Chem B 2018; 122:8047-8055. [DOI: 10.1021/acs.jpcb.8b03945] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Ilia V. Kopanichuk
- Institute of Chemistry, St. Petersburg State University, 7-9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Ekaterina A. Vedenchuk
- Institute of Chemistry, St. Petersburg State University, 7-9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Alina S. Koneva
- Institute of Chemistry, St. Petersburg State University, 7-9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Aleksandr A. Vanin
- Institute of Chemistry, St. Petersburg State University, 7-9 Universitetskaya nab., St. Petersburg 199034, Russia
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11
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Vierros S, Österberg M, Sammalkorpi M. Aggregation response of triglyceride hydrolysis products in cyclohexane and triolein. Phys Chem Chem Phys 2018; 20:27192-27204. [DOI: 10.1039/c8cp05104f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aggregation mechanism and the existence of cmc depend on apolar solvent quality and surfactant head group polarity.
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Affiliation(s)
- Sampsa Vierros
- Department of Chemistry and Materials Science
- Aalto University
- 00076 Aalto
- Finland
| | - Monika Österberg
- Department of Bioproducts and Biotechnology
- Aalto University
- 00076 Aalto
- Finland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science
- Aalto University
- 00076 Aalto
- Finland
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12
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Surfactant chain length and concentration influence on the interfacial tension of two immiscible model liquids: a coarse-grained approach. J Mol Model 2017; 23:306. [PMID: 28986687 DOI: 10.1007/s00894-017-3474-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/17/2017] [Indexed: 10/18/2022]
Abstract
The interfacial tension between immiscible liquids is studied as a function of a model linear surfactant length and concentration using coarse-grained, dissipative particle dynamics numerical simulations. The adsorption isotherms obtained from the simulations are found to be in agreement with Langmuir's model. The reduction of the interfacial tension with increasing surfactant concentration is found to display some common characteristics for all the values of chain length modeled, with our predictions being in agreement with Szyszkowski's equation. Lastly, the critical micelle concentration is predicted for all surfactant lengths, finding exponentially decaying behavior, in agreement with Kleven's model. It is argued that these findings can be helpful guiding tools in the interpretation of available experiments and in the design of new ones with new surfactants and polymers.
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13
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Senac C, Urbach W, Kurtisovski E, Hünenberger PH, Horta BAC, Taulier N, Fuchs PFJ. Simulating Bilayers of Nonionic Surfactants with the GROMOS-Compatible 2016H66 Force Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10225-10238. [PMID: 28832154 DOI: 10.1021/acs.langmuir.7b01348] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Polyoxyethylene glycol alkyl ether amphiphiles (CiEj) are important nonionic surfactants, often used for biophysical and membrane protein studies. In this work, we extensively test the GROMOS-compatible 2016H66 force field in molecular dynamics simulations involving the lamellar phase of a series of CiEj surfactants, namely C12E2, C12E3, C12E4, C12E5, and C14E4. The simulations reproduce qualitatively well the monitored structural properties and their experimental trends along the surfactant series, although some discrepancies remain, in particular in terms of the area per surfactant, the equilibrium phase of C12E5, and the order parameters of C12E3, C12E4, and C12E5. The polar head of the CiEj surfactants is highly hydrated, almost like a single polyethyleneoxide (PEO) molecule at full hydration, resulting in very compact conformations. Within the bilayer, all CiEj surfactants flip-flop spontaneously within tens of nanoseconds. Water-permeation is facilitated, and the bending rigidity is 4 to 5 times lower than that of typical phospholipid bilayers. In line with another recent theoretical study, the simulations show that the lamellar phase of CiEj contains large hydrophilic pores. These pores should be abundant in order to reproduce the comparatively low NMR order parameters. We show that their contour length is directly correlated to the order parameters, and we estimate that they should occupy approximately 7-10% of the total membrane area. Due to their highly dynamic nature (rapid flip-flops, high water permeability, observed pore formation), CiEj surfactant bilayers are found to represent surprisingly challenging systems in terms of modeling. Given this difficulty, the results presented here show that the 2016H66 parameters, optimized independently considering pure-liquid as well as polar and nonpolar solvation properties of small organic molecules, represent a good starting point for simulating these systems.
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Affiliation(s)
- Caroline Senac
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale , F-75006 Paris, France
| | - Wladimir Urbach
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale , F-75006 Paris, France
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University; Université Paris Diderot, Sorbonne Paris-Cité; Sorbonne Universités UPMC Univ Paris 06, CNRS , 24 rue Lhomond, 75005 Paris, France
| | - Erol Kurtisovski
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale , F-75006 Paris, France
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University; Université Paris Diderot, Sorbonne Paris-Cité; Sorbonne Universités UPMC Univ Paris 06, CNRS , 24 rue Lhomond, 75005 Paris, France
| | | | - Bruno A C Horta
- Instituto de Química, Universidade Federal do Rio de Janeiro , Rio de Janeiro 21941-909, Brazil
| | - Nicolas Taulier
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale , F-75006 Paris, France
| | - Patrick F J Fuchs
- Institut Jacques Monod, UMR 7592 CNRS, Université Paris Diderot , Sorbonne Paris Cité, F-75205 Paris, France
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14
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Aferni AE, Guettari M, Tajouri T. Determination of the Water/AOT/Isooctane Reverse Micelles Size Parameters from Their Refractive Index Data. J SOLUTION CHEM 2017. [DOI: 10.1007/s10953-016-0563-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Khan MF, Singh MK, Sen S. Measuring Size, Size Distribution, and Polydispersity of Water-in-Oil Microemulsion Droplets using Fluorescence Correlation Spectroscopy: Comparison to Dynamic Light Scattering. J Phys Chem B 2016; 120:1008-20. [DOI: 10.1021/acs.jpcb.5b09920] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mohammad Firoz Khan
- Spectroscopy Laboratory,
School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Moirangthem Kiran Singh
- Spectroscopy Laboratory,
School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sobhan Sen
- Spectroscopy Laboratory,
School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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16
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Anwar MF, Yadav D, Jain S, Kapoor S, Rastogi S, Arora I, Samim M. Size- and shape-dependent clinical and mycological efficacy of silver nanoparticles on dandruff. Int J Nanomedicine 2016; 11:147-61. [PMID: 26792991 PMCID: PMC4708193 DOI: 10.2147/ijn.s86828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Dandruff is a prominent scalp problem caused by the growth of fungus Malassezia furfur, potentially cascading into dermal inflammation, itching, and tissue damage. The present work outlines a detailed analysis of the treatment of scalp infection using silver nanomaterials (Ag NMs), and focuses on biocidal activity owing to manipulation of size, shape, and structure. Monodisperse silver spherical nanoparticles (NPs) and nanorods (NRs) were synthesized by chemical routes that were characterized using analytical and spectroscopic techniques. Ag NMs demonstrated enhanced biocidal tendencies compared to market available drugs, itracanozole and ketoconazole, showing greater zones of inhibition. The obtained 20 nm and 50 nm spherical-shaped NPs and 50 nm NRs showed concentration-, size-, and shape-dependent antifungal activity, with 20 nm spherical-shaped NPs exhibiting excellent potency. Minimum inhibitory concentration for 20 nm was lowest at 0.2 mg/mL in comparison to 0.3 mg/mL for NRs. Primary irritation index was 0.33 and 0.16 for 20 nm and 50 nm spherical-shaped NPs, respectively, while 50 nm rod-shaped NMs exhibited negligible redness. An in vivo model for M. furfur infection was generated by passing fungi subcutaneously in rats' skin. Again, 20 nm particles showed best normalization of skin after 10 days on regular dosing, in comparison with bigger and rod-shaped particles. The statistical clinical score was highest for Ag nanorods, followed by 50 nm Ag NPs-treated animals. It was observed that 20 nm spherical particles exhibited the lowest score (0) compared with others as well as with antifungal drugs. Biochemical analysis performed by checking antioxidant enzymatic activities indicated tissue repair and normalization of enzymes and protein concentration by Ag NPs.
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Affiliation(s)
- Mohammad F Anwar
- Department of Chemistry, Faculty of Science, Jamia Hamdard University, New Delhi, India
| | - Deepak Yadav
- Faculty of Medicine, Jamia Hamdard University, New Delhi, India
| | - Swati Jain
- Amity Institute of Nanotechnology, Amity University, Noida, Uttar Pradesh, India
| | - Sumeet Kapoor
- Centre for Biomedical Engineering, Indian Institute of Technology, Delhi, India
| | - Shweta Rastogi
- Department of Chemistry, Hans Raj College, University of Delhi, Delhi, India
| | - Indu Arora
- Department of Biomedical Sciences, Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, India
| | - Mohammed Samim
- Department of Chemistry, Faculty of Science, Jamia Hamdard University, New Delhi, India
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17
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Vierros S, Sammalkorpi M. Phosphatidylcholine reverse micelles on the wrong track in molecular dynamics simulations of phospholipids in an organic solvent. J Chem Phys 2015; 142:094902. [DOI: 10.1063/1.4914022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S. Vierros
- Department of Chemistry, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - M. Sammalkorpi
- Department of Chemistry, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
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18
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Vierros S, Sammalkorpi M. Role of hydration in phosphatidylcholine reverse micelle structure and gelation in cyclohexane: a molecular dynamics study. Phys Chem Chem Phys 2015; 17:14951-60. [DOI: 10.1039/c5cp01799h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Molecular simulations reveal lipid headgroup hydration is at key role in organogel transition in lecithin–water–cyclohexane systems.
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Affiliation(s)
- S. Vierros
- Department of Chemistry
- Aalto University
- 00076 Aalto
- Finland
| | - M. Sammalkorpi
- Department of Chemistry
- Aalto University
- 00076 Aalto
- Finland
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19
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Agazzi FM, Correa NM, Rodriguez J. Molecular dynamics simulation of water/BHDC cationic reverse micelles. structural characterization, dynamical properties, and influence of solvent on intermicellar interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9643-9653. [PMID: 25068175 DOI: 10.1021/la501964q] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report results obtained from molecular dynamics (MD) experiments of benzylhexadecyldimethylammonium chloride (BHDC) cationic reverse micelles (RMs). In particular we analyzed equilibrium and dynamical characteristics of water/BHDC RMs in pure benzene, at two different water/BHDC ratios (W0 = 5 and W0 = 10). The RMs appear as elliptical aggregates with eccentricities close to ∼0.9. Analysis of the different spatial correlations reveals three different spatial domains in the RMs: a water inner pool, the surfactant interface, and the external solvent. The calculated accessible surface areas for the aqueous inner cores suggest a strong penetration of solvent molecules within the micellar interface domains. Comparison between the density profiles of both RMs shows an increment of the broadness in the distributions of all species at the interface, along with an increasing overlap between the tail segments of the surfactant and benzene molecules as one considers larger micelles. For the dynamical side, the rotational characteristic time scale for the confined water was found to be 1 order of magnitude larger than that of the bulk water. A similar effect was also observed for hydrogen bond dynamics. Both retardation effects diminish with the size of the aggregate. To the estimate the influence of the external solvent on the intermicellar interactions, free energy profiles for the coalescence process between RMs of similar size in pure benzene and in a n-heptane/benzene mixture were also investigated. The results indicate that the association process is facilitated by the presence of n-heptane in the external nonpolar phase. Comparison with previous theoretical and experimental results is also carried out.
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Affiliation(s)
- Federico M Agazzi
- Departamento de Quı́mica, Universidad Nacional de Rı́o Cuarto , Agencia Postal 3, C.P. X5804BYA Rı́o Cuarto, Argentina
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20
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Effects of water content and oil on physicochemical and microenvironmental properties of mixed surfactant microemulsions. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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Interfacial composition and characterization of a quaternary water-in-oil mixed surfactant (cationic of different alkyl chain lengths+polyoxyethylene type nonionic) microemulsions in absence and presence of inorganic salts. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2013.04.049] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Guchhait B, Biswas R, Ghorai PK. Solute and Solvent Dynamics in Confined Equal-Sized Aqueous Environments of Charged and Neutral Reverse Micelles: A Combined Dynamic Fluorescence and All-Atom Molecular Dynamics Simulation Study. J Phys Chem B 2013; 117:3345-61. [DOI: 10.1021/jp310285k] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Biswajit Guchhait
- Department
of Chemical, Biological and
Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt
Lake, Kolkata 700098, India
| | - Ranjit Biswas
- Department
of Chemical, Biological and
Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt
Lake, Kolkata 700098, India
| | - Pradip K. Ghorai
- Indian Institute of Science Education and Research, Kolkata, Mohanpur Campus, Nadia 741252,
India
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23
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Correa NM, Silber JJ, Riter RE, Levinger NE. Nonaqueous Polar Solvents in Reverse Micelle Systems. Chem Rev 2012; 112:4569-602. [DOI: 10.1021/cr200254q] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N. Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Juana J. Silber
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Ruth E. Riter
- Department of Chemistry, Agnes Scott College, Decatur, Georgia 30030-3770, United
States
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872,
United States
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24
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Chowdhary J, Ladanyi BM. Molecular simulation study of water mobility in aerosol-OT reverse micelles. J Phys Chem A 2011; 115:6306-16. [PMID: 21548627 DOI: 10.1021/jp201866t] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In this work, we present results from molecular dynamics simulations on the single-molecule relaxation of water within reverse micelles (RMs) of different sizes formed by the surfactant aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulfosuccinate) in isooctane. Results are presented for RM water content w(0) = [H(2)O]/[AOT] in the range from 2.0 to 7.5. We show that translational diffusion of water within the RM can, to a good approximation, be decoupled from the translation of the RM through the isooctane solvent. Water translational mobility within the RM is restricted by the water pool dimensions, and thus, the water mean-squared displacements (MSDs) level off in time. Comparison with models of diffusion in confined geometries shows that a version of the Gaussian confinement model with a biexponential decay of correlations provides a good fit to the MSDs, while a model of free diffusion within a sphere agrees less well with simulation results. We find that the local diffusivity is considerably reduced in the interfacial region, especially as w(0) decreases. Molecular orientational relaxation is monitored by examining the behavior of OH and dipole vectors. For both vectors, orientational relaxation slows down close to the interface and as w(0) decreases. For the OH vector, reorientation is strongly affected by the presence of charged species at the RM interface and these effects are especially pronounced for water molecules hydrogen-bonded to surfactant sites that serve as hydrogen-bond acceptors. For the dipole vector, orientational relaxation near the interface slows down more than that for the OH vector due mainly to the influence of ion-dipole interactions with the sodium counterions. We investigate water OH and dipole reorientation mechanisms by studying the w(0) and interfacial shell dependence of orientational time correlations for different Legendre polynomial orders.
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Affiliation(s)
- Janamejaya Chowdhary
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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25
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Minakova M, Savelyev A, Papoian GA. Nonequilibrium Water Transport in a Nonionic Microemulsion System. J Phys Chem B 2011; 115:6503-8. [DOI: 10.1021/jp201431u] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maria Minakova
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Alexey Savelyev
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
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26
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Rosenfeld DE, Schmuttenmaer CA. Dynamics of the Water Hydrogen Bond Network at Ionic, Nonionic, and Hydrophobic Interfaces in Nanopores and Reverse Micelles. J Phys Chem B 2010; 115:1021-31. [PMID: 21182316 DOI: 10.1021/jp109599q] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Daniel E. Rosenfeld
- Department of Chemistry, Yale University, 225 Prospect Street, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Charles A. Schmuttenmaer
- Department of Chemistry, Yale University, 225 Prospect Street, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
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27
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Abel S, Waks M, Marchi M. Molecular dynamics simulations of cytochrome c unfolding in AOT reverse micelles: The first steps. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 32:399-409. [PMID: 20803162 DOI: 10.1140/epje/i2010-10635-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 07/06/2010] [Indexed: 05/29/2023]
Abstract
This paper explores the reduced form of horse cytochrome c confined in reverse micelles (RM) of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) in isooctane by molecular dynamics simulation. RMs of two sizes were constructed at a water content of W (o) = [ H₂O ]/[AOT] = 5.5 and 9.1. Our results show that the protein secondary structure and the heme conformation both depend on micellar hydration. At low hydration, the protein structure and the heme moiety remain stable, whereas at high water content the protein becomes unstable and starts to unfold. At W (o) = 9.1 , according to the X-ray structure, conformational changes are mainly localized on protein loops and around the heme moiety, where we observe a partial opening of the heme crevice. These findings suggest that within our time window (10ns), the structural changes observed at the heme level are the first steps of the protein denaturation process, previously described experimentally in micellar solutions. In addition, a specific binding of AOT molecules to a few lysine residues of the protein was found only in the small-sized RM.
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Affiliation(s)
- S Abel
- DSV/iBiTecS/SB2SM, CNRS URA, Gif-sur-Yvette, France.
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28
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Sterpone F, Briganti G, Pierleoni C. Sphere versus cylinder: the effect of packing on the structure of nonionic C12E6 micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8960-8967. [PMID: 19588924 DOI: 10.1021/la900591e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Two independent series of calculations are performed simulating spherical and cylindrical C12E6 micelles in a temperature range around the experimental sphere-to-rod transition temperature for surfactant concentrations less than 20% by weight. A comparative analysis of these systems helps to shed light on the microscopic details of the micelle sphere-to-rod transition. In agreement with theoretical models, we find that spherical and cylindrical micelles have a different oil core packing; the core radius of a cylindrical micelle is reduced by a factor of 0.87 with respect to the core radius of a spherical micelle. Despite this contraction, the specific volume of the alkyl tails is larger in a cylindrical micelle than in a spherical micelle. In both geometries, this specific volume follows the same linear increase with temperature. Density measurement experiments are also performed in order to evaluate the specific volume of the hydrophobic tail of surfactants of the C12Ej family with j ranging from 5 to 8. We observe a good agreement between experimental data and simulation results. Our simulations also show that the spatial distribution of the head groups in the interface is more effective in screening the oil core in the cylindrical aggregate than in the spherical aggregate, reducing by a factor of 2 the oil surface per monomer exposed to water. This screening accounts for a free-energy difference of Deltafs=fssph-fscyl approximately +2.5kBT per monomer and mirrors the essential role that the hydrophobic interactions have on the shape transition. We also find that the different interface packing correlates with different conformations and flexibility of the hydrophilic fragments E6, that appear as an entropic reservoir for the transition. Finally, comparing the degree of hydration of a spherical micelle at T=283 K with that of a cylindrical micelle at T=318 K, we observe an amount of dehydration in agreement with reported experimental data across the sphere-to-rod transition. However, for aggregates of fixed shape, we find a much smaller amount of dehydration with temperature, suggesting that the shape transition is not a consequence of the measured temperature dehydration but rather the opposite.
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29
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Pomata MHH, Laria D, Skaf MS, Elola MD. Molecular dynamics simulations of AOT-water/formamide reverse micelles: Structural and dynamical properties. J Chem Phys 2008; 129:244503. [DOI: 10.1063/1.3042275] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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30
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Mitra RK, Sinha SS, Verma PK, Pal SK. Modulation of Dynamics and Reactivity of Water in Reverse Micelles of Mixed Surfactants. J Phys Chem B 2008; 112:12946-53. [DOI: 10.1021/jp803585q] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rajib Kumar Mitra
- Unit for Nano Science & Technology, Department of Chemical, Biological & Macromolecular Sciences, S.N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, INDIA
| | - Sudarson Sekhar Sinha
- Unit for Nano Science & Technology, Department of Chemical, Biological & Macromolecular Sciences, S.N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, INDIA
| | - Pramod Kumar Verma
- Unit for Nano Science & Technology, Department of Chemical, Biological & Macromolecular Sciences, S.N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, INDIA
| | - Samir Kumar Pal
- Unit for Nano Science & Technology, Department of Chemical, Biological & Macromolecular Sciences, S.N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, INDIA
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31
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Marque G, Neyertz S, Verdu J, Prunier V, Brown D. Molecular Dynamics Simulation Study of Water in Amorphous Kapton. Macromolecules 2008. [DOI: 10.1021/ma702173j] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Grégory Marque
- LMOPS, UMR CNRS 5041, Université de Savoie, Bâtiment IUT, 73376 Le Bourget-du-Lac, France, LIM, UMR CNRS 8006, ENSAM, 151 Boulevard de l’Hôpital, 75013 Paris, France, and EDF R&D, Site des Renardières, 77818 Moret-sur-Loing, France
| | - Sylvie Neyertz
- LMOPS, UMR CNRS 5041, Université de Savoie, Bâtiment IUT, 73376 Le Bourget-du-Lac, France, LIM, UMR CNRS 8006, ENSAM, 151 Boulevard de l’Hôpital, 75013 Paris, France, and EDF R&D, Site des Renardières, 77818 Moret-sur-Loing, France
| | - Jacques Verdu
- LMOPS, UMR CNRS 5041, Université de Savoie, Bâtiment IUT, 73376 Le Bourget-du-Lac, France, LIM, UMR CNRS 8006, ENSAM, 151 Boulevard de l’Hôpital, 75013 Paris, France, and EDF R&D, Site des Renardières, 77818 Moret-sur-Loing, France
| | - Valéry Prunier
- LMOPS, UMR CNRS 5041, Université de Savoie, Bâtiment IUT, 73376 Le Bourget-du-Lac, France, LIM, UMR CNRS 8006, ENSAM, 151 Boulevard de l’Hôpital, 75013 Paris, France, and EDF R&D, Site des Renardières, 77818 Moret-sur-Loing, France
| | - David Brown
- LMOPS, UMR CNRS 5041, Université de Savoie, Bâtiment IUT, 73376 Le Bourget-du-Lac, France, LIM, UMR CNRS 8006, ENSAM, 151 Boulevard de l’Hôpital, 75013 Paris, France, and EDF R&D, Site des Renardières, 77818 Moret-sur-Loing, France
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32
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Park S, Moilanen DE, Fayer MD. Water DynamicsThe Effects of Ions and Nanoconfinement. J Phys Chem B 2008; 112:5279-90. [DOI: 10.1021/jp7121856] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sungnam Park
- Department of Chemistry Stanford University, Stanford, California 94305
| | - David E. Moilanen
- Department of Chemistry Stanford University, Stanford, California 94305
| | - M. D. Fayer
- Department of Chemistry Stanford University, Stanford, California 94305
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33
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Moilanen DE, Levinger NE, Spry DB, Fayer MD. Confinement or the nature of the interface? Dynamics of nanoscopic water. J Am Chem Soc 2007; 129:14311-8. [PMID: 17958424 PMCID: PMC2532509 DOI: 10.1021/ja073977d] [Citation(s) in RCA: 194] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of water confined in two different types of reverse micelles are studied using ultrafast infrared pump-probe spectroscopy of the hydroxyl OD stretch of HOD in H2O. Reverse micelles of the surfactant Aerosol-OT (ionic head group) in isooctane and the surfactant Igepal CO 520 (nonionic head group) in 50/50 wt % cyclohexane/hexane are prepared to have the same diameter water nanopools. Measurements of the IR spectra and vibrational lifetimes show that the identity of the surfactant head groups affects the local environment experienced by the water molecules inside the reverse micelles. The orientational dynamics (time-dependent anisotropy), which is a measure of the hydrogen bond network rearrangement, are very similar for the confined water in the two types of reverse micelles. The results demonstrate that confinement by an interface to form a nanoscopic water pool is a primary factor governing the dynamics of nanoscopic water rather than the presence of charged groups at the interface.
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Affiliation(s)
| | | | - D. B. Spry
- Department of Chemistry, Stanford University 94305
| | - M. D. Fayer
- Department of Chemistry, Stanford University 94305
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34
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Das D, Nath DN. Temperature-Dependent Magnetic Field Effect Study on Exciplex Luminescence: Probing the Triton X-100 Reverse Micelle in Cyclohexane. J Phys Chem B 2007; 111:11009-15. [PMID: 17725343 DOI: 10.1021/jp073252w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The microenvironment within the reverse micelle of the nonionic surfactant Triton X-100 (TX-100) in cyclohexane has been investigated by studying the magnetic field effect (MFE) on pyrene-dimethylaniline exciplex luminescence. The nature of exciplex fluorescence and its behavior in the presence of a magnetic field have been found to vary significantly with the water content of the medium. Results are discussed in light of multiple exciplex formation within the micelle which is further supported by the fluorescence lifetime measurements. Those exciplexes emitting at longer wavelength are found to be magnetic field sensitive while those emitting toward the blue region of the spectrum are insensitive toward magnetic field. Since the exciplex's emission characteristics and magnetic field sensitivity depend on its immediate surrounding, it has been concluded that the environment within the micelle is nonuniform. With an increase in hydration level, different zones of varying polarity are created within the reverse micelle. It has been pointed out that the magnetic field sensitive components reside inside the polar core of the micelle while those located near the hydrocarbon tail are field insensitive. However it has been presumed that an interconversion between the different types of exciplexes is possible. The environment within the reverse micelle is found to be largely affected by the change in temperature, and this is reflected in the exciplex emission property and the extent of magnetic field effect. Interestingly, the variation of MFE with temperature follows different trends in the dry and the wet reverse micelle. A comparison has been drawn with the reverse micelle of the ionic surfactant to get an insight into the difference between the various types of micellar environment.
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Affiliation(s)
- Doyel Das
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032, India
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35
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Rodriguez J, Martí J, Guàrdia E, Laria D. Protons in Non-ionic Aqueous Reverse Micelles. J Phys Chem B 2007; 111:4432-9. [PMID: 17425361 DOI: 10.1021/jp0703410] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Using molecular dynamics techniques, we investigate the solvation of an excess proton within an aqueous reverse micelle in vacuo, with the neutral surfactant diethylene glycol monodecyl ether [CH3(CH2)11(OC2H4)2OH]. The simulation experiments were performed using a multistate empirical valence bond Hamiltonian model. Our results show that the stable solvation environments for the excess proton are located in the water-surfactant interface and that its first solvation shell is composed exclusively by water molecules. The relative prevalence of Eigen- versus Zundel-like solvation structures is investigated; compared to bulk results, Zundel-like structures in micelles become somewhat more stable. Characteristic times for the proton translocation jumps have been computed using population relaxation time correlation functions. The micellar rate for proton transfer is approximately 40x smaller than that found in bulk water at ambient conditions. Differences in the computed rates are examined in terms of the hydrogen-bond connectivity involving the first solvation shell of the excess charge with the rest of the micellar environment. Simulation results would indicate that proton transfers are correlated with rare episodes during which the HB connectivity between the first and second solvation shells suffers profound modifications.
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Affiliation(s)
- Javier Rodriguez
- Departamento de Química Inorgánica, Analítica y Qumica-Física e INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 1428, Buenos Aires, Argentina
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