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Stackhouse CI, Pierson KN, Labrecque CL, Mawson C, Berg J, Fuglestad B, Nucci NV. Characterization of 10MAG/LDAO reverse micelles: Understanding versatility for protein encapsulation. Biophys Chem 2024; 311:107269. [PMID: 38815545 DOI: 10.1016/j.bpc.2024.107269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/17/2024] [Accepted: 05/20/2024] [Indexed: 06/01/2024]
Abstract
Reverse micelles (RMs) are spontaneously organizing nanobubbles composed of an organic solvent, surfactants, and an aqueous phase that can encapsulate biological macromolecules for various biophysical studies. Unlike other RM systems, the 1-decanoyl-rac-glycerol (10MAG) and lauryldimethylamine-N-oxide (LDAO) surfactant system has proven to house proteins with higher stability than other RM mixtures with little sensitivity to the water loading (W0, defined by the ratio of water to surfactant). We investigated this unique property by encapsulating three model proteins - cytochrome c, myoglobin, and flavodoxin - in 10MAG/LDAO RMs and applying a variety of experimental methods to characterize this system's behavior. We found that this surfactant system differs greatly from the traditional, spherical, monodisperse RM population model. 10MAG/LDAO RMs were discovered to be oblate ellipsoids at all conditions, and as W0 was increased, surfactants redistributed to form a greater number of increasingly spherical ellipsoidal particles with pools of more bulk-like water. Proteins distinctively influence the thermodynamics of the mixture, encapsulating at their optimal RM size and driving protein-free RM sizes to scale accordingly. These findings inform the future development of similarly malleable encapsulation systems and build a foundation for application of 10MAG/LDAO RMs to analyze biological and chemical processes under nanoscale confinement.
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Affiliation(s)
- Crystal I Stackhouse
- Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States; Department of Biomedical and Biological Sciences, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States.
| | - Kali N Pierson
- Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States; Department of Biomedical and Biological Sciences, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States.
| | - Courtney L Labrecque
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States.
| | - Cara Mawson
- Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States; Department of Biomedical and Biological Sciences, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States.
| | - Joshua Berg
- Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States; Department of Biomedical and Biological Sciences, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States
| | - Brian Fuglestad
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States; Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, Virginia 23219, United States.
| | - Nathaniel V Nucci
- Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States; Department of Biomedical and Biological Sciences, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, United States.
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Niwano M, Ma T, Iwata K, Tadaki D, Yamamoto H, Kimura Y, Hirano-Iwata A. Two-dimensional water-molecule-cluster layers at nanobubble interfaces. J Colloid Interface Sci 2023; 652:1775-1783. [PMID: 37678082 DOI: 10.1016/j.jcis.2023.08.173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 08/18/2023] [Accepted: 08/27/2023] [Indexed: 09/09/2023]
Abstract
HYPOTHESIS Bulk nanobubbles (NBs) have high surface charge densities and long lifetimes. Despite several attempts to understand the lifetime of NBs, their interfacial layer structure remains unknown. It is hypothesized that a specific interfacial layer exists with a hydrogen bond network that stabilizes NBs. EXPERIMENTS In situ infrared reflectance-absorption spectroscopy and density functional theory were used to determine the interfacial layer structure of NBs. Furthermore, nuclear magnetic resonance spectroscopy was used to examine the interfacial layer hardness of bubbles filled with N2, O2, and CO2, which was expected to depend on the encapsulated gas species. FINDINGS The interfacial layer was composed of three-, four-, and five-membered ring clusters of water molecules. An interface model was proposed in which a two-dimensional layer of clusters with large electric dipole moments is oriented toward the endohedral gas, and the hydrophobic surface is adjacent to the free water. The interfacial layer hardness was dependent on the interaction with the gas (N2 > O2 > CO2), which supports the proposed interface model. These findings can be generalized to the structure of water at gas-water interfaces.
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Affiliation(s)
- Michio Niwano
- Laboratory for Nano-electronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi 980-8577, Japan.
| | - Teng Ma
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Kazuki Iwata
- Faculty of Comprehensive Management, Tohoku Fukushi University, Sendai, Miyagi 989-3201, Japan
| | - Daisuke Tadaki
- Laboratory for Nano-electronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Hideaki Yamamoto
- Laboratory for Nano-electronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Yasuo Kimura
- Department of Electric and Electronic Engineering, Tokyo University of Technology, Hachioji, Tokyo 192-0983, Japan
| | - Ayumi Hirano-Iwata
- Laboratory for Nano-electronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi 980-8577, Japan; Faculty of Comprehensive Management, Tohoku Fukushi University, Sendai, Miyagi 989-3201, Japan
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Chen Q, Denisov SA, Dobrovolskii D, Mostafavi M. Observation of Nanoconfinement Effect on the Kinetics of Hydrated Electron in the Nanoscale Water Pools of Water-AOT-Cyclohexane Microemulsions by Picosecond Pulse Radiolysis. J Phys Chem B 2023; 127:7974-7982. [PMID: 37681575 DOI: 10.1021/acs.jpcb.3c04302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
The decay kinetics of the hydrated electron (eaq-) in aerosol OT (AOT)-based ternary microemulsions with pool sizes ranging from 0.34 to 4.85 nm were studied using picosecond pulse radiolysis coupled with transient absorption UV-vis spectroscopy. Electron transfer from oil to water and the subsequent solvation occurred within a time resolution of 7 ps. The decay kinetics of eaq- were accurately modeled using a double-exponential decay model, revealing the occurrence of two types of reactions, i.e., the recombination reaction at the water-oil interface and the radical-radical reactions in the water pools. The apparent lifetimes of both types of decays decreased significantly as the size of water pools decreased, indicating the influence of nanoconfinement effects. Moreover, the importance of the water-oil interface increased with decreasing water content, regardless of the presence or absence of NO3- as an electron scavenger in the water pools. Our findings provide a comprehensive understanding on the kinetics of the radiation reaction in AOT-based microemulsions.
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Affiliation(s)
- Qingde Chen
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay, 91405 Orsay, Cedex, France
- Beijing National Laboratory for Molecular Sciences, Fundamental Science on Radiochemistry and Radiation Chemistry Laboratory, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Sergey A Denisov
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay, 91405 Orsay, Cedex, France
| | - Denis Dobrovolskii
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay, 91405 Orsay, Cedex, France
| | - Mehran Mostafavi
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay, 91405 Orsay, Cedex, France
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Enhanced Hydrodynamic Radius of AOT/n-heptane/Water Reverse Micellar System Through Altered Electrostatic Interactions and Molecular Self-Assemblies. J Fluoresc 2021; 31:1475-1488. [PMID: 34283329 DOI: 10.1007/s10895-021-02760-x] [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: 04/01/2021] [Accepted: 06/01/2021] [Indexed: 02/01/2023]
Abstract
We have demonstrated a unique approach to alter the aqueous pool size of an AOT/n-heptane/water reverse micellar system. A positively charged dye Rhodamine B (RhB) and negatively charged Rose Bengal (RB) were incorporated in the reverse micellar pool to investigate the effect of electrostatic interactions and stacking effects among the dye molecules on the AOT/n-heptane/water interface. Dynamic light scattering revealed increase in reverse micellar pool size in presence of positively charged dye aggregates at the oil-water interface. However, less expansion was observed in presence of negatively charged dye aggregates (RB). This confirms the role of electrostatic interaction in modulating the hydrodynamic radius. A head-to-tail type of stacking of RhB molecules at the interface favors this expansion. The differences in stacking of the two dyes inside the reverse micelles and their torsional mobility indicated the role of the reverse micellar interface and H-bonding ability of the microenvironment on dye aggregation. Conductivity measurements demonstrated a significant drop in percolation temperature of the reverse micellar system in presence of dye aggregates. This confirms the effect of dye aggregation and electrostatic interaction on such expansion. This strategy can be exploited for solubilizing greater amounts and a wider variety of drug molecules in microemulsions.
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Plastinin IV, Burikov SA, Dolenko TA. Laser diagnostics of reverse microemulsions: Influence of the size and shape of reverse micelles on the Raman spectrum on the example of water/AOT/cyclohexane system. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.115153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ridley RE, Alvarado E, Mrse AA, Vasquez VR, Graeve OA. Phase Stability and Miscibility in Ethanol/AOT/ n-Heptane Systems: Evidence of Multilayered Cylindrical and Spherical Microemulsion Morphologies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11274-11283. [PMID: 32897721 DOI: 10.1021/acs.langmuir.0c01851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We describe the effects of ethanol on the phase behavior of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in n-heptane. Using dynamic light scattering (DLS), molecular dynamics (MD) simulations, and nuclear magnetic resonance (1H NMR) spectroscopy, we investigate the aggregation behavior of AOT across a wide range of ethanol/AOT/n-heptane compositions. We conclude that reverse micelles do not form at any of the investigated concentrations. Instead, we observe the formation of other surfactant aggregate morphologies unique to this system, namely, multilayered cylindrical structures and spherical AOT-in-ethanol structures, which vary significantly with changes in ethanol concentration. We also identify mixed-solvent polarity as a driving factor for the surfactant behavior in the system. When the concentration of ethanol is 20 wt % or below, the system is inhomogeneous with varying sizes of AOT, ethanol, and AOT + ethanol aggregates, with the ethanol primarily exhibiting a cosurfactant behavior, almost exclusively binding at the surface of AOT aggregates. With increased ethanol concentration, the ethanol in the system also exhibits solvent-like behaviors in addition to the cosurfactant behaviors. Most significantly, when the ethanol concentration is raised above 35 wt %, the transition to solvent-like behavior allows AOT Na+ counterions to dissociate from the headgroups and they are dissolved in the ethanol. We use these results to construct a preliminary phase diagram for the ethanol/AOT/n-heptane system.
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Affiliation(s)
- Robyn E Ridley
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093-0411, United States
| | - Erick Alvarado
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093-0411, United States
| | - Anthony A Mrse
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0307, United States
| | - Victor R Vasquez
- Chemical and Materials Engineering, University of Nevada, Reno, Nevada 89557, United States
| | - Olivia A Graeve
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093-0411, United States
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Adhikari S, Mukherjee T. Kinetics of Free Radical Reactions of Some Biologically Important Compounds as Studied by Pulse Radiolysis. PROGRESS IN REACTION KINETICS AND MECHANISM 2019. [DOI: 10.3184/007967401103165307] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Soumyakanti Adhikari
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Tulsi Mukherjee
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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9
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Lépori CMO, Correa NM, Silber JJ, Vaca Chávez F, Falcone RD. Interfacial properties modulated by the water confinement in reverse micelles created by the ionic liquid-like surfactant bmim-AOT. SOFT MATTER 2019; 15:947-955. [PMID: 30644504 DOI: 10.1039/c8sm02217h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The behavior of the interfacial water entrapped in reverse micelles (RMs) that were formed by the ionic liquid-like surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT) was investigated with the use of UV-Vis absorption spectroscopy and nuclear magnetic resonance (NMR) relaxometry. The solvatochromism of two molecular probes, namely, 1-methyl-8-oxyquinolinium betaine (QB) and N,N,N',N'-tetramethylethylenediamine copper(ii)acetylacetonate tetraphenylborate ([Cu(acac)(tmen)][B(C6H5)4]), was investigated. As a comparison, the analog RMs formed by sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) were also explored. By varying the water content inside the RMs and consequently the different magnitude of the water-surfactant interactions at the interface, interesting properties were observed by comparing bmim-AOT and Na-AOT RMs. From the solvatochromic behavior of ([Cu(acac)(tmen)][B(C6H5)4]), we found that the interface in bmim-AOT RMs shows a smaller electron donating capacity than that in Na-AOT RMs. QB revealed that the interfacial region is a weaker hydrogen bond donor and less polar than the corresponding Na-AOT RMs. NMR experiments showed that the molecular motion of water in bmim-AOT RMs is less restricted than that of the water molecules confined in Na-AOT RMs. In summary, the results show how the nature of the bmim+ cation affects the interaction between the entrapped water and the RM interface, greatly modifying the interfacial water structure in comparison with the results known for Na-AOT.
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Affiliation(s)
- Cristian M O Lépori
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3, C.P. X5804BYA Río Cuarto, Argentina.
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Biswas R, Bagchi B. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:013001. [PMID: 29205175 DOI: 10.1088/1361-648x/aa9b1d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water-surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface-water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of the same due to interaction with the surfaces.
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11
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Honegger P, Schmollngruber M, Steinhauser O. Micellar confinement disrupts collective structure and accelerates collective dynamics of encapsulated water. Phys Chem Chem Phys 2018; 20:11454-11469. [DOI: 10.1039/c8cp01508b] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Detailed numerical study of the dielectric spectrum of zwitterionic reverse micelles is combined with interpretation using a new semi-quantitative analytical model.
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Affiliation(s)
- Philipp Honegger
- University of Vienna
- Faculty of Chemistry
- Department of Computational Biological Chemistry
- A-1090 Vienna
- Austria
| | - Michael Schmollngruber
- University of Vienna
- Faculty of Chemistry
- Department of Computational Biological Chemistry
- A-1090 Vienna
- Austria
| | - Othmar Steinhauser
- University of Vienna
- Faculty of Chemistry
- Department of Computational Biological Chemistry
- A-1090 Vienna
- Austria
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12
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13
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Kundu K, Bardhan S, Ghosh S, Saha SK, Paul BK. Formation of Oil/Water Interface by Mixed Surface Active Ionic Liquid-Ethoxylated Alkyl Ether: Energetics, Microstructures, Solvation Dynamics, and Antimicrobial Activity. ChemistrySelect 2016. [DOI: 10.1002/slct.201601449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kaushik Kundu
- Surface and Colloid Science Laboratory, Geological Studies Unit; Indian Statistical Institute; 203, B.T. Road Kolkata- 700 108 India
- Department Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore- 560012 India
| | - Soumik Bardhan
- Department of Chemistry; University of North Bengal; Darjeeling- 734 013 India
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences; Indian Institute of Technology Madras; Chennai- 600036 India
| | - Soumen Ghosh
- Center for Surface Science, Department of Chemistry; Jadavpur University; Kolkata- 700032 India
| | - Swapan K. Saha
- Department of Chemistry; University of North Bengal; Darjeeling- 734 013 India
| | - Bidyut K. Paul
- Surface and Colloid Science Laboratory, Geological Studies Unit; Indian Statistical Institute; 203, B.T. Road Kolkata- 700 108 India
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Wiebenga-Sanford BP, DiVerdi J, Rithner CD, Levinger NE. Nanoconfinement's Dramatic Impact on Proton Exchange between Glucose and Water. J Phys Chem Lett 2016; 7:4597-4601. [PMID: 27779880 DOI: 10.1021/acs.jpclett.6b01651] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Glucose nanoconfined by solubilization in water-containing AOT (sodium bis(2-ethylhexyl) sulfosuccinate) reverse micelles has been investigated using 1H NMR. NMR spectra reveal well-defined signals for the glucose hydroxyl groups that suggest slow chemical exchange between them and the water hydroxyl groups. Using the EXSY (ZZ-exchange) method, the chemical exchange rate from water to glucose hydroxyl groups was measured for glucose in reverse micelles as a function of size (water pool diameter of ∼1-5 nm) at 25 °C. The chemical exchange rates observed in the nanoconfined interior are dramatically slower (5-20 times) than those observed for glucose in bulk aqueous solution at the same concentration as the micelle interior. Exchange rate constants are calculated via a mechanism that accounts for these observations, and implications of these results are presented and discussed.
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Affiliation(s)
| | - Joseph DiVerdi
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| | - Christopher D Rithner
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| | - Nancy E Levinger
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
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Park HR, Seo JJ, Park CH, Yu D, Bark KM. Spectroscopic Properties of Apigenin in Various Bulk Solutions and Aerosol-OT Reverse Micelles. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hyoung-Ryun Park
- Department of Chemistry and Research Institute of Basic Science; Chonnam National University; Gwangju Korea
| | - Jung-Ja Seo
- Department of Chemistry and Research Institute of Basic Science; Chonnam National University; Gwangju Korea
| | - Chul-Ho Park
- Department of Cosmetic Science; Nambu University; Gwangju Korea
| | - Duan Yu
- Department of Chemistry; Gyeongsang National University; Jinju Korea
| | - Ki-Min Bark
- Department of Chemical Education and Research Institute of Life Science; Gyeongsang National University; Jinju Korea
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16
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Jayasooriya UA, Clayden NJ, Steytler DC, Oganesyan VS, Peck JNT, Khasanov R, Scheuermann R, Stoykov A. Rate of Molecular Transfer of Allyl Alcohol across an AOT Surfactant Layer Using Muon Spin Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:664-672. [PMID: 26716949 DOI: 10.1021/acs.langmuir.5b03482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of transverse field muon spin rotation (TF-μSR), avoided level crossing muon spin resonance (ALC-μSR), and Monte Carlo simulations. Reverse microemulsions consist of nanometer-sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer. Although the thermodynamic, static model of these systems has been well described, our understanding of their dynamics is currently incomplete. For example, what is the rate of solute transfer between the aqueous and apolar solvents, and how this is influenced by the structure of the interface? With an appropriate choice of system and probe molecule, μSR offers a unique opportunity to directly probe these interfacial transfer dynamics. Here, we have employed a well characterized w/o microemulsion stabilized by bis(2-ethylhexyl) sodium sulfosuccinate (Aerosol OT), with allyl alcohol (CH2═CH-CH2-OH, AA) as the probe. Resonances due to both muoniated radicals, CMuH2-C*H-CH2-OH and C*H2-CHMu-CH2-OH, were observed with the former being the dominant species. All resonances displayed solvent dependence, with those in the microemulsion observed as a single resonance located at intermediate magnetic fields to those present in either of the pure solvents. Observation of a single resonance is strong evidence for interfacial transfer being in the fast exchange limit. Monte Carlo calculations of the ΔM = 0 ALC resonances are consistent with the experimental data, indicating exchange rates greater than 10(9) s(-1), placing the rate of interfacial transfer at the diffusion limit.
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Affiliation(s)
- Upali A Jayasooriya
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - Nigel J Clayden
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - David C Steytler
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - Vasily S Oganesyan
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - Jamie N T Peck
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - Rustem Khasanov
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut , WBBA/120, CH-5232 Villigen PSI, Switzerland
| | - Robert Scheuermann
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut , WBBA/120, CH-5232 Villigen PSI, Switzerland
| | - Alexey Stoykov
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut , WBBA/120, CH-5232 Villigen PSI, Switzerland
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Souza FD, Souza BS, Tondo DW, Leopoldino EC, Fiedler HD, Nome F. Imidazolium-based zwitterionic surfactants: characterization of normal and reverse micelles and stabilization of nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3587-3595. [PMID: 25742026 DOI: 10.1021/la504802k] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper presents the physicochemical properties of micellar aggregates formed from a series of zwitterionic surfactants of the type 3-(1-alkyl-3-imidazolio)propane-sulfonate (ImS3-n), with n = 10, 12, 14, and 16. The ImS3-n dipolar ionic surfactants represent a versatile class of dipolar ionic compounds, which form normal and reverse micelles. Furthermore, they are able to stabilize nanoparticles in water and in organic media. Aqueous solubility is too low at room temperature to allow characterization of micellar aggregates but increases with addition of salts, allowing determination of aggregation number and cmc. As expected, these parameters depend on the length of the alkyl chain, and cmc values follow Klevens equation. In the presence of NaClO4, all ImS3-n micelles become anionoid by incorporating ClO4(-) on the micellar interface. A special feature of these surfactants is the ability to form reverse micelles and solubilize copious amounts of saline solutions in chloroform. (1)H NMR and infrared spectroscopic evidence showed that the maximum water to surfactant molar ratio w0 achievable depends on the concentration and type of salt dissolved. Reverse micelles of the ImS3-n surfactants can be used to stabilize metallic nanoparticles, whose size may be tuned by the amount of water dissolved.
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Affiliation(s)
- Franciane D Souza
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil
| | - Bruno S Souza
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil
| | - Daniel W Tondo
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil
| | - Elder C Leopoldino
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil
| | - Haidi D Fiedler
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil
| | - Faruk Nome
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil
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18
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Nanda R, Kumar A. Phase Behavior, Diffusion, Structural Characteristics, and pH of Aqueous Hydrophobic Ionic Liquid Confined Media: Insights into Microviscosity and Microporsity in the [C4C4im][NTf2] + Water System. J Phys Chem B 2015; 119:1641-53. [DOI: 10.1021/jp511318t] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Raju Nanda
- Physical and Material Chemistry
Division, National Chemical Laboratory, Pune-411008, India
| | - Anil Kumar
- Physical and Material Chemistry
Division, National Chemical Laboratory, Pune-411008, India
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19
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Maity B, Chatterjee A, Ahmed SA, Seth D. Photophysics of crystal violet lactone in reverse micelles and its dual behaviour. RSC Adv 2015. [DOI: 10.1039/c5ra06309d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The photophysics of Crystal Violet Lactone (CVL) in aqueous and non aqueous reverse micelles (RMs) have been studied. It was observed that in RMs, the CTA → CTB transformation is retarded.
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Affiliation(s)
- Banibrata Maity
- Department of Chemistry
- Indian Institute of Technology Patna
- Patna 800013
- India
| | - Aninda Chatterjee
- Department of Chemistry
- Indian Institute of Technology Patna
- Patna 800013
- India
| | | | - Debabrata Seth
- Department of Chemistry
- Indian Institute of Technology Patna
- Patna 800013
- India
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20
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den Dunnen A, van der Niet MJTC, Badan C, Koper MTM, Juurlink LBF. Long-range influence of steps on water adsorption on clean and D-covered Pt surfaces. Phys Chem Chem Phys 2015; 17:8530-7. [DOI: 10.1039/c4cp03165b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water wets the D-covered Pt(111) surface (right), while it clusters at steps of D-covered Pt(533), (755), and (977) (left).
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Affiliation(s)
- Angela den Dunnen
- Leiden Institute of Chemistry
- Leiden University
- 2300 RA Leiden
- The Netherlands
| | | | - Cansin Badan
- Leiden Institute of Chemistry
- Leiden University
- 2300 RA Leiden
- The Netherlands
| | - Marc T. M. Koper
- Leiden Institute of Chemistry
- Leiden University
- 2300 RA Leiden
- The Netherlands
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21
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Kuchlyan J, Banik D, Kundu N, Ghosh S, Banerjee C, Sarkar N. Effect of confinement on excited-state proton transfer of firefly's chromophore D-luciferin in AOT reverse micelles. J Phys Chem B 2014; 118:3401-8. [PMID: 24624892 DOI: 10.1021/jp500210n] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Excited-state intermolecular proton transfer of D-luciferin in reverse micelles has been investigated using steady-state and time-resolved fluorescence spectroscopy measurement. The different polar cores have been chosen for the study of proton transfer dynamics in aerosol-OT (AOT) reverse micelles. It is shown that aqueous reverse micelle is the suitable environment for the photoprotolytic reaction of D-luciferin. The neutral form of the chromophore is present both in ground and excited state at W0 = 0. The proton transfer in nanometer size water pool of water/AOT/n-heptane begins at W0 = 8 and increases with increasing W0 values. However, the intermolecular excited-state proton transfer (ESPT) of D-luciferin is inhibited in nonaquous reverse micelles with DMF and DMSO as a polar core. Thus, the requirement of ESPT of D-luciferin to take place in reverse micelles consists of polar protic solvent like water as a polar core.
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Affiliation(s)
- Jagannath Kuchlyan
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, WB, India
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22
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Park HR, Im SE, Seo JJ, Bark KM. Spectroscopic Properties of Quercetin in AOT Reverse Micelles. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.3.828] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Determination of Aggregation Parameters of Hexadecyltrimethylammonium Bromide from Probe Absorption. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.199200067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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24
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Singh PK, Kuroda DG, Hochstrasser RM. An ion's perspective on the molecular motions of nanoconfined water: a two-dimensional infrared spectroscopy study. J Phys Chem B 2013; 117:9775-84. [PMID: 23855349 DOI: 10.1021/jp406725a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The vibrational population relaxation and hydration shell dynamics of the symmetric tricyanomethanide (TCM) anion are investigated in a sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle as a function of the water pool radius. Two-dimensional infrared (IR) spectroscopy in combination with linear absorption and ultrafast IR pump-probe spectroscopy is utilized in this study. Spectroscopic measurements show that the anion has two bands in the 2160-2175 cm(-1) region, each with its own spectroscopic signatures. Analysis of the vibrational dynamics shows that the two vibrational bands are consistent with the anion located either at the interface or in the water pool. The sensitivity of the TCM anion to the environment allows us to unequivocally monitor the vibrational and hydration dynamics of the anion in those two different environments. A TCM anion located at the interface does not show any significant variation of the vibrational dynamics with the water pool size. On the contrary, the TCM anion inside the water pool exhibits a large and nonlinear variation of the vibrational lifetime and the frequency-frequency correlation time with the pool radius. Moreover, for the solvated anion in water pools of 49 Å in radius (W0 = 30), the vibrational lifetime reaches the values observed for the anion in bulk water while the frequency-frequency correlation time shows a characteristic time higher than that observed in the bulk. In addition, for the first time a model is developed and used to explain the observed nonlinear variation of the spectroscopic observables with the pool size. This model attributes the changes in the vibrational dynamics of the TCM anion in the water pool to the slow and radius-dependent water dynamics present in the confined environment of a reverse micelle.
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Affiliation(s)
- Prabhat K Singh
- Ultrafast Optical Processes Laboratory, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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25
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Nagalakshmi KV, Padma M, Shyamala P, Srikanth V, Satyanarayana A, SubbaRao PV. Catalytic effect of CTAB reverse micelles on the kinetics of dissociation of bis(2,4,6–tripyridyl-s-triazine) iron(II). TRANSIT METAL CHEM 2013. [DOI: 10.1007/s11243-013-9719-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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26
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Physicochemical studies of mixed surfactant microemulsions with isopropyl myristate as oil. J Colloid Interface Sci 2013; 402:180-9. [DOI: 10.1016/j.jcis.2013.04.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/04/2013] [Accepted: 04/05/2013] [Indexed: 11/19/2022]
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27
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Chatterjee A, Maity B, Seth D. The photophysics of 7-(N,N′-diethylamino)coumarin-3-carboxylic acid in water/AOT/isooctane reverse micelles: an excitation wavelength dependent study. Phys Chem Chem Phys 2013; 15:1894-906. [DOI: 10.1039/c2cp43483k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Giustini M, Giuliani AM, Gennaro G. Natural or synthetic nucleic acids encapsulated in a closed cavity of amphiphiles. RSC Adv 2013. [DOI: 10.1039/c3ra23208e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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29
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Kundu K, Guin G, Paul BK. Interfacial composition, thermodynamic properties, and structural parameters of water-in-oil microemulsions stabilized by 1-pentanol and mixed surfactants. J Colloid Interface Sci 2012; 385:96-110. [DOI: 10.1016/j.jcis.2012.06.057] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/28/2022]
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30
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Kosmella S, Koetz J. Polymer-modified w/o microemulsions - with tunable droplet-droplet interactions. Curr Opin Colloid Interface Sci 2012. [DOI: 10.1016/j.cocis.2012.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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31
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Kong B, Yu J, Savino K, Zhu Y, Guan B. Synthesis of α-calcium sulfate hemihydrate submicron-rods in water/n-hexanol/CTAB reverse microemulsion. Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2012.05.041] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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32
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Interfacial composition, thermodynamic properties and structural parameters of water-in-oil microemulsions stabilized by 1-pentanol and mixed anionic + polyoxyethylene type nonionic surfactants. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-012-2763-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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33
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Law SJ, Britton MM. Sizing of reverse micelles in microemulsions using NMR measurements of diffusion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11699-11706. [PMID: 22794150 DOI: 10.1021/la300796u] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This paper reports the size of reverse micelles (RMs) in AOT/octane/H(2)O and CTAB/hexanol/H(2)O microemulsions using magnetic resonance (MR) pulsed field gradient (PFG) measurements of diffusion. Diffusion data were measured using the pulsed gradient stimulated echo (PGSTE) experiment for surfactant molecules residing in the RM interface. Inverse Laplace transformation of these data generated diffusion coefficients for the RMs, which were converted into hydrodynamic radii using the Stokes-Einstein relation. This technique is complementary to those previously used to size RMs, such as dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS), but also offers several advantages, which are discussed. RM sizes, determined using the PGSTE method, in the AOT (sodium bis(2-ethylhexyl) sulfosuccinate) and CTAB (cetyltrimethylammonium bromide) microemulsions were compared with previous DLS and SAXS data, showing good agreement. Methods for determining number distributions from the PGSTE data, through the use of scaling factors, were investigated.
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Affiliation(s)
- Susan J Law
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
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34
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Valle L, Morán Vieyra FE, Borsarelli CD. Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment. Photochem Photobiol Sci 2012; 11:1051-61. [DOI: 10.1039/c2pp05385c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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35
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Sharifi S, Kudla P, Oliveira CLP, Pedersen JS, Bergenholtz J. Variations in Structure Explain the Viscometric Behavior of AOT Microemulsions at Low Water/AOT Molar Ratios. Z PHYS CHEM 2011. [DOI: 10.1524/zpch.2012.0173] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The viscosity of AOT/water/decane water-in-oil microemulsions exhibits a well-known maximum as a function of water/AOT molar ratio, which is usually attributed to increased attractions among nearly spherical droplets. The maximum can be removed by adding salt or by changing the oil to CCl4. Systematic small-angle X-ray scattering (SAXS) measurements have been used to monitor the structure of the microemulsion droplets in the composition regime where the maximum appears. On increasing the droplet concentration, the scattering intensity is found to scale with the inverse of the wavevector, a behavior which is consistent with cylindrical structures. The inverse wavevector scaling is not observed when the molar ratio is changed, moving the system away from the value corresponding to the viscosity maximum. It is also not present in the scattering from systems containing enough added salt to essentially eliminate the viscosity maximum. An asymptotic analysis of the SA XS data, complemented by some quantitative modeling, is consistent with cylindrical growth of droplets as their concentration is increased. Such elongated structures are familiar from related AOT systems in which the sodium counterion has been exchanged for a divalent one. However, the results of this study suggest that the formation of non-spherical aggregates at low molar ratios is an intrinsic property of AOT.
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Affiliation(s)
- Soheil Sharifi
- University of Sistan and Baluchestan, Department of Physics, Zahedan, Iran
| | - Petra Kudla
- Beiersdorf AG, Structure analysis, Hamburg, Deutschland
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36
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Porcal GV, Chesta CA, Biasutti MA, Bertolotti SG, Previtali CM. Quenching of the triplet state of Safranine-O by aliphatic amines in AOT reverse micelles studied by transient absorption spectroscopy. Photochem Photobiol Sci 2011; 11:302-8. [PMID: 22105094 DOI: 10.1039/c1pp05252g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photophysics of Safranine-O (3,6-diamino-2,7-dimethyl-5 phenyl phenazinium chloride) (SfH(+)Cl(-)) was investigated in reverse micelles (RMs) of AOT (sodium bis(2-ethylhexyl)sulfosuccinate) with special emphasis on the triplet state processes. The triplet is formed in its monoprotonated form, independently of the pH of the water used to prepare the RMs. While the intersystem crossing quantum yields in RMs are similar to those in organic solvents, the triplet lifetime is much longer. Since the pH in the water pool of AOT RMs is close to 5 and the triplet state of the dye is subjected to proton quenching, the long lifetime indicates that the dye resides in a region where it cannot be reached by protons during its lifetime. All the measurements indicate that the dye is localized in the interface, sensing a medium of micropolarity similar to EtOH : water (3:1) mixtures. The quenching by aliphatic amines was also investigated. While the quenching by the hydrophobic tributylamine is similar to that in methanol, the hydro-soluble triethanolamine is one order of magnitude more effective in RMs than in homogeneous solution. In the latter case the quenching process is interpreted by a very fast intramicellar quenching, the overall kinetics being controlled by the exchange of amine molecules between RMs. Semireduced dye is formed in the quenching process in RMs in the di-protonated state with a comparable quantum yield to the monoprotonated state formed in homogeneous solvents. The results point to the advantage of the reverse micellar system for the generation of active radicals for the initiation of vinyl polymerization, since a much lower concentration of amine can be employed with similar quantum yields.
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Affiliation(s)
- Gabriela V Porcal
- Departamento de Química, Universidad Nacional de Río Cuarto, 5800, Río Cuarto, Argentina
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37
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Mandal HK, Majumdar T, Mahapatra A. Kinetics of basic hydrolysis of tris(1,10-phenanthroline)iron(II) in macromolecular assemblies of CTAB. INT J CHEM KINET 2011. [DOI: 10.1002/kin.20564] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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38
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Andújar-Matalobos M, García-Río L, López-García S, Rodríguez-Dafonte P. Polarity of the interface in ionic liquid in oil microemulsions. J Colloid Interface Sci 2011; 363:261-7. [PMID: 21820124 DOI: 10.1016/j.jcis.2011.06.066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/24/2011] [Accepted: 06/25/2011] [Indexed: 11/16/2022]
Abstract
Ionic liquid based microemulsions were characterized by absorption solvatochromic shifts, (1)H NMR and kinetic measurements in order to investigate the properties of the ionic liquid within the restricted geometry provided by microemulsions and the interactions of the ionic liquid with the interface. Experimental results show a significant difference between the interfaces of normal water and the new ionic liquid microemulsions. Absorption solvatochromic shift experiments and kinetic studies on the aminolysis of 4-nitrophenyl laurate by n-decylamine show that the polarity at the interface of the ionic liquid in oil microemulsions (IL/O) is higher than at the interface of water in oil microemulsions (W/O) despite the fact that the polarity of [bmim][BF(4)(-)] is lower than the polarity of water. (1)H NMR experiments showed that an increase in the ionic liquid content of the microemulsion led to an increase in the interaction between [bmim][BF(4)(-)] and TX-100. The reason for the higher polarity of the microemulsions with the ionic liquid can be explained in terms of the incorporation of higher levels of the ionic liquid at the interface of the microemulsions, as compared to water in the traditional systems.
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Affiliation(s)
- María Andújar-Matalobos
- Departamento de Química Física y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Universidad de Santiago, 15782 Santiago, Spain
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39
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Abstract
Nanoconfined liquids are of interest because of both their fundamental properties and their potential utility in an array of applications. The structure and dynamics of the liquid can be dramatically impacted by the geometrical constraints and the interactions with the interface. Understanding the molecular-level origins of these changes and how they are determined by the characteristics of the confining framework is the subject of ongoing experimental and theoretical studies. The progress and remaining challenges in these efforts are reviewed in the context of solvation dynamics and proton transfer reactions, processes that are strongly affected by nanoscale confinement.
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Affiliation(s)
- Ward H Thompson
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
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40
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Airoldi M, Gennaro G, Giomini M, Giuliani AM, Giustini M, Palazzo G. The CdCl2 effects on synthetic DNAs encaged in the nanodomains of a cationic water-in-oil microemulsion. Phys Chem Chem Phys 2011; 13:12293-304. [PMID: 21643617 DOI: 10.1039/c1cp20770a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The present work is dedicated to the study of the interactions of CdCl(2) with the synthetic polynucleotides polyAT and polyGC confined in the nanoscopic aqueous compartment of the water-in-oil microemulsion CTAB/pentanol/hexane/water, with the goal to mimic in vitro the situation met by the nucleic acids in vivo. In biological structures, in fact, very long strings of nucleic acids are segregated into very small compartments having a radius exceedingly smaller than the length of the encapsulated macromolecule. For comparison, the behaviour of polyGC was also studied in aqueous solutions of matched composition. The conformational and thermal stabilities of both polynucleotides enclosed in the inner compartment of the microemulsion are scarcely affected by the presence of CdCl(2), whereas in solution immediate and large effects were observed also at room temperature. The lack of effects of CdCl(2) on the properties of the biopolymers entrapped in the aqueous core of the microemulsion has been attributed to the peculiar characteristics of the medium (low dielectric constant, in particular) which cause a total repression of the CdCl(2) dissociation that is not complete even in water. In fact, several of the numerous effects of CdCl(2) observed on the conformational stability of polyGC in aqueous solutions have also been ascribed to the limited dissociation of the cadmium salt.
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Affiliation(s)
- Marta Airoldi
- Dipartimento di Chimica S. Cannizzaro, Università di Palermo, Palermo, Italy
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41
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Martinez AV, DeSensi SC, Dominguez L, Rivera E, Straub JE. Protein folding in a reverse micelle environment: the role of confinement and dehydration. J Chem Phys 2011; 134:055107. [PMID: 21303167 DOI: 10.1063/1.3545982] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Characterization of the molecular interactions that stabilize the folded state of proteins including hydrogen bond formation, solvation, molecular crowding, and interaction with membrane environments is a fundamental goal of theoretical biophysics. Inspired by recent experimental studies by Gai and co-workers, we have used molecular dynamics simulations to explore the structure and dynamics of the alanine-rich AKA(2) peptide in bulk solution and in a reverse micelle environment. The simulated structure of the reverse micelle shows substantial deviations from a spherical geometry. The AKA(2) peptide is observed to (1) remain in a helical conformation within a spherically constrained reverse micelle and (2) partially unfold when simulated in an unconstrained reverse micelle environment, in agreement with experiment. While aqueous solvation is found to stabilize the N- and C-termini random coil portions of the peptide, the helical core region is stabilized by significant interaction between the nonpolar surface of the helix and the aliphatic chains of the AOT surfactant. The results suggest an important role for nonpolar peptide-surfactant and peptide-lipid interactions in stabilizing helical geometries of peptides in reverse micelle environments.
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42
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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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43
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Astray G, Cid A, Manso JA, Mejuto JC, Moldes OA, Morales J. Alkaline Fading of Triarylmethyl Carbocations in Self-Assembly Microheterogeneous Media. PROGRESS IN REACTION KINETICS AND MECHANISM 2011. [DOI: 10.3184/146867811x12984793755693] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This review reports on the alkaline fading of crystal violet and other related carbocations in the presence of different microheterogeneous media (micelles, microemulsions and vesicles).
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Affiliation(s)
- G. Astray
- Physical Chemistry Department, Faculty of Science, University of Vigo at Ourense,32004-Ourense, Spain
| | - A. Cid
- Physical Chemistry Department, Faculty of Science, University of Vigo at Ourense,32004-Ourense, Spain
| | - J. A. Manso
- Physical Chemistry Department, Faculty of Science, University of Vigo at Ourense,32004-Ourense, Spain
| | - J. C. Mejuto
- Physical Chemistry Department, Faculty of Science, University of Vigo at Ourense,32004-Ourense, Spain
| | - O. A. Moldes
- Physical Chemistry Department, Faculty of Science, University of Vigo at Ourense,32004-Ourense, Spain
| | - J. Morales
- Physical Chemistry Department, Faculty of Science, University of Vigo at Ourense,32004-Ourense, Spain
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44
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Park HR, Liu HB, Shin SC, Park JK, Bark KM. Spectroscopic Properties of Quercetin-3-O-rhamnoside and Quercetin-3-O-rutinoside in Aerosol-OT Reverse Micelles. B KOREAN CHEM SOC 2011. [DOI: 10.5012/bkcs.2011.32.3.981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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45
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Blach D, Correa NM, Silber JJ, Falcone RD. Interfacial water with special electron donor properties: Effect of water–surfactant interaction in confined reversed micellar environments and its influence on the coordination chemistry of a copper complex. J Colloid Interface Sci 2011; 355:124-30. [DOI: 10.1016/j.jcis.2010.11.067] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Revised: 11/19/2010] [Accepted: 11/20/2010] [Indexed: 10/18/2022]
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Fang Y, Bennett A, Liu J. Selective transport of amino acids into the gas phase: driving forces for amino acid solubilization in gas-phase reverse micelles. Phys Chem Chem Phys 2011; 13:1466-78. [DOI: 10.1039/c0cp00823k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Sarangi MK, Dey D, Basu S. Influence of heterogeneity of confined water on photophysical behavior of acridine with amines: a time-resolved fluorescence and laser flash photolysis study. J Phys Chem A 2010; 115:128-35. [PMID: 21155585 DOI: 10.1021/jp107610k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The photophysical behavior of acridine (Acr) shows facilitated water-assisted protonation equilibrium between its deprotonted (Acr* ∼ 10 ns) and protonated forms (AcrH(+*) ∼ 28 ns) within confined region of ordered water molecules inside AOT/H(2)O/n-heptane reverse micelles (RMs). The time-resolved-area-normalized-emission spectra confirm both Acr* and AcrH(+*), while time-resolved-emission spectra depict time evolution between them. Quenching of AcrH(+*) with N,N-dimethylaniline (DMA) is a purely diffusion-controlled bimolecular quenching with linear Stern-Volmer (S-V) plot, while nonlinearity arises with triethylamine (TEA) that forms ground state complex with AcrH(+) (AcrH(+)··H(2)O··TEA) indicating both static and dynamic quenching. Transient intermediates, DMA(•+) and AcrH(•) infer photoinduced electron transfer from DMA to Acr, while those from AcrH(+)··H(2)O··TEA complex suggest water mediated excited-state proton transfer (ESPT) between AcrH(+) and TEA. The ESPT becomes faster in larger RMs due to enhanced mobility of hydronium ions in AcrH(+)··H(2)O··TEA, which reduces in smaller RMs as water becomes much more constrained owing to stronger complexation by excess confinement.
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Affiliation(s)
- Manas Kumar Sarangi
- Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064, India
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Chinelatto AM, Fonseca MTM, Kiyan NZ, Seoud OAE. Acid-Base Equilibria of Hydrophilic Indicators in Water-in-Oil Microemulsions. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19900940812] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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