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Faeder J, Ladanyi BM. Solvation Dynamics in Reverse Micelles: The Role of Headgroup−Solute Interactions. J Phys Chem B 2005; 109:6732-40. [PMID: 16851757 DOI: 10.1021/jp045202m] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We present molecular dynamics simulation results for solvation dynamics in the water pool of anionic-surfactant reverse micelles (RMs) of varying water content, w(0). The model RMs are designed to represent water/aerosol-OT/oil systems, where aerosol-OT is the common name for sodium bis(2-ethylhexyl)sulfosuccinate. To determine the effects of chromophore-headgroup interactions on solvation dynamics, we compare the results for charge localization in model ionic diatomic chromophores that differ only in charge sign. Electronic excitation in both cases is modeled as charge localization on one of the solute sites. We find dramatic differences in the solvation responses for anionic and cationic chromophores. Solvation dynamics for the cationic chromophore are considerably slower and more strongly w(0)-dependent than those for the anionic chromophore. Further analysis indicates that the difference in the responses can be ascribed in part to the different initial locations of the two chromophores relative to the surfactant interface. In addition, slow motion of the cationic chromophore relative to the interface is the main contributor to the longer-time decay of the solvation response to charge localization in this case.
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Affiliation(s)
- James Faeder
- Theoretical Biology and Biophysics Group, MS K710, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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102
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Oldfield C, Freedman RB, Robinson BH. Enzyme hyperactivity in AOT water-in-oil microemulsions is induced by ‘lone’ sodium counterions in the water-pool. Faraday Discuss 2005; 129:247-63; discussion 275-89. [PMID: 15715311 DOI: 10.1039/b406483f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water-in-oil microemulsions are thermodynamically stable single-phase dispersions of water and surfactant within a continuous oil phase. The classical ternary system, based on the surfactant sodium bis(2-ethylhexyl)sulfosuccinate ('AOT'), water and an alkane such as n-heptane, is an optically transparent monodispersion of spherical water-droplets coated with a close-packed surfactant monolayer and the droplet radius is, to a good first approximation, directly proportional to the molar water: surfactant ratio, R. Enzymes dissolved in the water droplets retain activity and stability. These systems have attracted interest as media for biotransformations. Principally based upon studies in AOT-stabilized w/o microemulsions, a peculiar feature of the kinetics of enzyme-catalyzed reactions has long been apparent: the reaction rate characteristically increases from around zero at R=3, through a maximum, in the range R= 10-20, and thereafter decreases again, so that plots of rate vs. R are characteristically 'bell-shaped'. Furthermore, at optimal R, enzymes seem to be 'hyperactive', i.e., they are more active, by a modest but significant factor of 2-3-fold, than in aqueous solution. In this paper we propose the hypothesis that this kind of R-dependence arises because of the presence of freely mobile lone surfactant counterions (Na+) within the water-pool. These ions have no charge partners within the water pool and consequently have a high electrochemical potential. According to our model, lone counterions facilitate the hydrolysis of ester or amide substrates, for example, by stabilizing the tetrahedral intermediate formed during the reaction through ion-pairing with the carbonyl oxygen of the substrate, thus facilitating transfer of negative charge from the carbonyl carbon as it is attacked by the incoming nucleophile. An expression for the relationship between the concentration of free counterions in the water-pool and the compositional parameter R leads directly, through Debye-Hückel theory, to an expression for the relationship between the reaction rate and R, log k(R)= log k(o) + C(1/R)1/2 where k(R) is the rate constant at some finite R, k(o) is the rate constant extrapolated to R = infinity and C is an R-independent coefficient. For enzymes that display bell-shaped kinetics, such as bovine alpha-chymotrypsin and Chromobacterium viscosum lipase, the descending part of the plot (i.e. from optimal R to high R) obeys this equation very well. Inspection of the above equation shows that the rate constant, k(R) is greater than k(o). Furthermore it is reasonable to equate k(o) with k(aq), the aqueous solution value of k since the condition R = infinity may be equated with the condition of infinite dilution with respect to counterions, so eliminating their specific effect on the kinetics. It follows from the inequality, k(R) > k(o) approximately equal to k(aq), that the enzyme is 'hyperactive' in the microemulsion compared with aqueous solution. We show that this is indeed the case for the chymotrypsin-catalyzed hydrolysis of N-trans-cinnamoylimidazole and the lipase catalyzed hydrolysis of 4-nitrophenyl acetate. The tailing off of enzyme activity at low R (< 10) is most likely due to conformational immobilization, probably due to partial dehydration in these low-water preparations (water activity, a(w), drops off rapidly below R = 15). We show that the reaction of glycylglycine with 4-nitrophenyl acetate, a 'hyperactive' non-enzymic reaction, does not suffer from this effect and obeys the above equation across the whole range of R.
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Affiliation(s)
- Christopher Oldfield
- Chemistry Research Group, MicroScience Technologies Ltd, Edinburgh, UK EH26 OPZ.
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103
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Izquierdo C, Casado J, Rodriguez A, Moyá ML. Microemulsions as a medium in chemical kinetics, II. The I−+ S2O8=and crystal Violet + OH−reactions in different surfactant/oil/water microemulsions. INT J CHEM KINET 2004. [DOI: 10.1002/kin.550240104] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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104
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Yamazaki K, Imai M, Suzuki I. Soybean lecithin hydrolysis using hog pancreas phospholipase A2 influenced by the hydrophobic character of W/O microemulsion systems. Biochem Eng J 2004. [DOI: 10.1016/j.bej.2004.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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105
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Hirose Y, Yui H, Sawada T. The Ultrafast Relaxation Dynamics of a Viscosity Probe Molecule in an AOT-Reversed Micelle: Contribution of the Specific Interactions with the Local Environment. J Phys Chem B 2004. [DOI: 10.1021/jp0370775] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yasushi Hirose
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan, and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Hiroharu Yui
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan, and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Tsuguo Sawada
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan, and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
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106
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García-Río L, Mejuto JC, Pérez-Lorenzo M. Modification of reactivity by changing microemulsion composition. Basic hydrolysis of nitrophenyl acetate in AOT/isooctane/water systems. NEW J CHEM 2004. [DOI: 10.1039/b401226g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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107
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Kataoka H, Eguchi T, Masui H, Miyakubo K, Nakayama H, Nakamura N. Scaling Relation between Electrical Conductivity Percolation and Water Diffusion Coefficient in Sodium Bis(2-ethylhexyl) Sulfosuccinate-Based Microemulsion. J Phys Chem B 2003. [DOI: 10.1021/jp020510a] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hiroshi Kataoka
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Taro Eguchi
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hirotsugu Masui
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Keisuke Miyakubo
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hirokazu Nakayama
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Nobuo Nakamura
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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108
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Chen C, Ou-Yang CC, Yeh CW. Synthesis of galactooligosaccharides and transgalactosylation modeling in reverse micelles. Enzyme Microb Technol 2003. [DOI: 10.1016/s0141-0229(03)00155-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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109
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Aoudia M, Rodgers MAJ. Photoprocesses in AOT Reverse Micelles Containing Metalloporphyrins and Oligopeptides. J Phys Chem B 2003. [DOI: 10.1021/jp027106w] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Aoudia
- Department of Chemistry, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khod, Sultanate of Oman, and Center for Photochemical Science, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - M. A. J. Rodgers
- Department of Chemistry, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khod, Sultanate of Oman, and Center for Photochemical Science, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
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110
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111
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Marhuenda-Egea FC, Piera-Velázquez S, Cadenas C, Cadenas E. Mechanism of adaptation of an atypical alkaline p-nitrophenyl phosphatase from the archaeon Halobacterium salinarum at low-water environments. Biotechnol Bioeng 2002; 78:497-502. [PMID: 12115118 DOI: 10.1002/bit.10216] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Enzymes suspended in organic solvents represent a versatile system for studying the involvement of water in catalytic properties and their flexibility in adapting to different environmental conditions. The extremely halophilic alkaline p-nitrophenylphosphate phosphatase from the archaeon Halobacterium salinarum was solubilized in an organic medium consisting of reversed micelles of hexadecyltrimethylammoniumbromide in cyclohexane, with 1-butanol as cosurfactant. Hydrolysis of p-nitrophenylphosphate was nonlinear with time when the enzyme was microinjected into reversed micelles that contained substrate. These data are consistent with a kinetic model in which the enzyme is irreversibly converted from an initial form to a final stable form during the first seconds of the encapsulation process. The model features a rate constant (k) for that transition and separate hydrolysis rates, v(1) and v(2), for the two forms of the enzyme. The enzyme conversion may be governed by the encapsulation process.
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Affiliation(s)
- Frutos C Marhuenda-Egea
- División de Bioquímica, Facultad de Ciencias, Universidad de Alicante, Aptdo. 99, 03080 Alicante, Spain.
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112
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Bulavchenko AI, Batishchev AF, Batishcheva EK, Torgov VG. Modeling of the Electrostatic Interaction of Ions in Dry, Isolated Micelles of AOT by the Method of Direct Optimization. J Phys Chem B 2002. [DOI: 10.1021/jp0144000] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. I. Bulavchenko
- Institute of Inorganic Chemistry and Institute of Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A. F. Batishchev
- Institute of Inorganic Chemistry and Institute of Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - E. K. Batishcheva
- Institute of Inorganic Chemistry and Institute of Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - V. G. Torgov
- Institute of Inorganic Chemistry and Institute of Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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113
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Melo EP, Aires-Barros MR, Cabral JM. Reverse micelles and protein biotechnology. BIOTECHNOLOGY ANNUAL REVIEW 2002; 7:87-129. [PMID: 11686050 DOI: 10.1016/s1387-2656(01)07034-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Reverse micelles are nanometer-sized (1-10 nm) water droplets dispersed in organic media obtained by the action of surfactants. Surfactant molecules organize with the polar part to the inner side able to solubilize water and the apolar part in contact with the organic solvent. Proteins can be solubilized in the water pool of reverse micelles. Studies on the structure-function relationships of proteins in reverse micelles are very important since the microenvironment in which the protein is solubilized has physico-chemical properties distinct from a bulk aqueous solution. Some of the unique characteristics of reverse micelles make them very useful for biotechnological applications. Charge and hydrophilic/hydrophobic characteristics of the protein and the selection of surfactant can be used to achieve selective solubilization of proteins. This has been used to extend the classical liquid-liquid extraction with solvents to protein bioseparation. For biocatalysis the presence of a bulk organic solvent allow synthetic reactions to be performed via the control of water content and the solubilization of hydrophobic substrates. This is accomplished with a higher interfacial area (about 100 m2/mL) than the conventional biphasic systems, minimizing mass transfer problems.
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Affiliation(s)
- E P Melo
- Universidade do Algarve-F.E.R.N., Campus de Gambelas, 8000 Faro, Portugal.
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114
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Akiyama K, Tero-Kubota S. One- and Two-Dimensional EPR Studies on the Radical Pair Generated by the Photoreduction of 9,10-Anthraquinone-1,5-disulfonate in Aerosol OT Reverse Micelles. J Phys Chem B 2002. [DOI: 10.1021/jp0155157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kimio Akiyama
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Shozo Tero-Kubota
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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115
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Absorption and Emission Characteristics of 7-Hydroxycoumarin and 1-Hydroxypyrene-3,6,8-trisulfonate in Water/Oil Microemulsion with Reference to the Determination of the Interfacial and Bulk pH of the Water Pool. J Colloid Interface Sci 2001. [DOI: 10.1006/jcis.2001.7919] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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116
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117
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Costa SM, López-Cornejo P, Togashi DM, Laia CA. Photoinduced electron transfer in non-aqueous microemulsions. J Photochem Photobiol A Chem 2001. [DOI: 10.1016/s1010-6030(01)00509-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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118
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Nandi S, Bhattacharya SC. Alkanol effects on fluorescence quenching of Safranine T by thiourea in reverse micellar medium of Aerosol–O–T in heptane. Colloids Surf A Physicochem Eng Asp 2001. [DOI: 10.1016/s0927-7757(00)00822-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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119
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Li Q, Li T, Wu J. Electrical Conductivity of Water/Sodium Bis(2-ethylhexyl) Sulfosuccinate/n-Heptane and Water/Sodium Bis(2-ethylhexyl) Phosphate/n-Heptane Systems: The Influences of Water Content, Bis(2-ethylhexyl) Phosphoric Acid, and Temperature. J Colloid Interface Sci 2001; 239:522-527. [PMID: 11427019 DOI: 10.1006/jcis.2001.7613] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Conductance behaviors of reverse micelles/microemulsions have been investigated by means of electrical conductometry, with em-phasis on the influences of water content, bis(2-ethylhexyl) phos-phoric acid (HDEHP) content, and temperature. Two systems were prepared and studied, i.e., sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in n-heptane (H(2)O/AOT/n-heptane) and sodium bis(2-ethylhexyl) phosphate (NaDEHP) in n-heptane (H(2)O/NaDEHP/ n-heptane). The conductance behaviors of AOT+HDEHP and NaDEHP+HDEHP systems are dependent upon water content (W(0), expressed as the molar ratio of solubilized water and surfactant(s)), HDEHP content, and temperature. With an increase of water content, the conductivity-W(0) curves of the AOT+HDEHP system show maximum conductivity and no percolation conductance, different from that of the AOT system. The conductivity of the NaDEHP+HDEHP system varies with the NaDEHP to HDEHP ratio. For the systems with the NaDEHP to HDEHP ratios of 80 : 20 and 70 : 30, both maximum conductivity and percolation phenomenon can be observed, while for the system with the NaDEHP to HDEHP ratio of 90 : 10, neither maximum conductance nor percolation conductance occurs. With varying temperature, markedly different conductance behaviors were observed in AOT+HDEHP and NaDEHP+HDEHP systems. Percolation conductance occurs in the AOT+HDEHP system and the onset temperature for percolation conductance decreases with increasing water content and/or HDEHP content. In the H(2)O/(NaDEHP, HDEHP)/n-heptane system, however, the conductivity decreases markedly with increasing temperature until a minimum, followed by a slow recovery of the conductivity. These phenomena could be attributed to the different aggregation states of the surfactants and the different transition mechanisms of charge carriers in respective systems at different water contents, HDEHP contents, and temperatures. Copyright 2001 Academic Press.
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Affiliation(s)
- Quan Li
- College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
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120
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Chowdhury PK, Ashby KD, Datta A, Petrich JW. Effect of pH on the fluorescence and absorption spectra of hypericin in reverse micelles. Photochem Photobiol 2000; 72:612-8. [PMID: 11107845 DOI: 10.1562/0031-8655(2000)072<0612:eopotf>2.0.co;2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The well-characterized, monodispersed nature of reverse micelles formed by sodium bis(2-ethylhexyl)sulfosuccinate/heptane and their usefulness in approximating a membrane-like environment have been exploited to investigate the effect of pH and water pool size on the photophysical properties of hypericin (Hyp). Our measurements reveal two titratable groups of pKa approximately 1.5 and approximately 12.5. These are assigned to the HypH+/Hyp equilibrium (the deprotonation of a carbonyl group) and the Hyp-/Hyp2- equilibrium (the deprotonation of a peri hydroxyl group). The low-energy absorbance maxima of HypH+, of Hyp and Hyp- and of Hyp2- are 583, 594 and 613 nm, respectively. Neither at pH 13 nor at 1 M HCl is the system entirely in the Hyp2- or the HypH+ forms. Ours is the first study of Hyp in reverse micelles as well as the first time-resolved study of Hyp as a function of pH.
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Affiliation(s)
- P K Chowdhury
- Department of Chemistry, Iowa State University, Ames 50011, USA
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121
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Andrade SM, Costa SM. The location of tryptophan, N-acetyltryptophan and alpha-chymotrypsin in reverse micelles of AOT: a fluorescence study. Photochem Photobiol 2000; 72:444-50. [PMID: 11045712 DOI: 10.1562/0031-8655(2000)072<0444:tlotna>2.0.co;2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The spectroscopic properties of alpha-chymotrypsin (alpha-Chym), L-tryptophan (Trp) and N-acetyl-L-tryptophan (NAT) solubilized in hydrated reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate in iso-octane were followed by fluorescence as a function of the amount of intramicellar water and initial pH. The lack of pH dependence observed for Trp in these systems, as opposed to what occurs in bulk water, and the similarities found for the protein in both media foresee different locations of these probes. In reverse micelles, fluorescence quenching studies using acrylamide emphasize the existence of structural alterations within the protein when its global charge changes from positive (pH = 7) to negative (pH = 10). The ensemble of the data points to an interfacial location of the zwitterionic Trp, an intermediate region of less tightly bound water for the location of the anionic Trp and NAT and an almost bulk water environment for alpha-Chym.
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Affiliation(s)
- S M Andrade
- Centro de Química Estrutural, Instituto Superior Técnico, Lisboa, Portugal
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122
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Uskova MA, Borst JW, Hink MA, van Hoek A, Schots A, Klyachko NL, Visser AJ. Fluorescence dynamics of green fluorescent protein in AOT reversed micelles. Biophys Chem 2000; 87:73-84. [PMID: 11036971 DOI: 10.1016/s0301-4622(00)00184-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We have used the enhanced green fluorescent protein (EGFP) to investigate the properties of surfactant-entrapped water pools in organic solvents (reversed micelles) with steady-state and time-resolved fluorescence methods. The surfactant used was sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and the organic solvents were isooctane and (the more viscous) dodecane, respectively. The water content of the water pools could be controlled through the parameter w0, which is the water-to-surfactant molar ratio. With steady-state fluorescence, it was observed that subtle fluorescence changes could be noted in reversed micelles of different water contents. EGFP can be used as a pH-indicator of the water droplets in reversed micelles. Time-resolved fluorescence methods also revealed subtle changes in fluorescence decay times when the results in bulk water were compared with those in reversed micelles. The average fluorescence lifetimes of EGFP scaled with the relative fluorescence intensities. Time-resolved fluorescence anisotropy of EGFP in aqueous solution and reversed micelles yielded single rotational correlation times. Geometrical considerations could assign the observed correlation times to dehydrated protein at low w0 and internal EGFP rotation within the droplet at the highest w0.
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Affiliation(s)
- M A Uskova
- MicroSpectroscopy Centre, Department of Biomolecular Sciences, Wageningen University, The Netherlands
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123
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Li Q, Li T, Wu J. Comparative Study on the Structure of Reverse Micelles. 2. FT-IR, 1H NMR, and Electrical Conductance of H2O/AOT/NaDEHP/n-Heptane Systems. J Phys Chem B 2000. [DOI: 10.1021/jp000336v] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Quan Li
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Tao Li
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jinguang Wu
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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124
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Li Q, Li T, Wu J, Zhou N. Comparative Study on the Structure of Water in Reverse Micelles Stabilized with Sodium Bis(2-ethylhexyl) Sulfosuccinate or Sodium Bis(2-ethylhexyl) Phosphate in n-Heptane. J Colloid Interface Sci 2000; 229:298-302. [PMID: 10942571 DOI: 10.1006/jcis.2000.7030] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The microstructure of water solubilized in H(2)O/surfactant/n-heptane ternary systems has been investigated by employing (1)H-NMR and FT-IR spectroscopic techniques. Two reverse micellar systems were prepared and studied, i.e., sodium bis(2-ethylhexyl) sulfosuccinate in n-heptane (H(2)O/AOT/n-heptane) and sodium bis(2-ethylhexyl) phosphate in n-heptane (H(2)O/NaDEHP/n-heptane). (1)H-NMR data showed that the chemical shift of water protons for the AOT and NaDEHP reverse micelles varied downfield and upfield, respectively, with an increase of the water content. The opposite shift directions with increasing water content are interpreted as due to a composition change of the solubilized water associated with head-groups and sodium counterions in reverse micellar systems. On the basis of deconvolution results of FT-IR spectra, a four-component model is proposed to interpret the FT-IR and (1)H-NMR results. Copyright 2000 Academic Press.
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Affiliation(s)
- Q Li
- College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
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125
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Sommerville ML, Cain JB, Johnson CS, Hickey AJ. Lecithin inverse microemulsions for the pulmonary delivery of polar compounds utilizing dimethylether and propane as propellants. Pharm Dev Technol 2000; 5:219-30. [PMID: 10810752 DOI: 10.1081/pdt-100100537] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Lecithin inverse microemulsions were investigated as a means of pulmonary drug delivery, utilizing dimethylethyleneglycol (DMEG) and hexane as models for dimethyl ether (DME) and propane, respectively. Addition of lecithin to the model propellant mixtures increased the solubility of water in a nonlinear, solvent-dependent manner. The concentration of water necessary to fully hydrate cobalt(II) decreased as the solvent composition was varied from DMEG to hexane. Water proton chemical shift increased in the presence of lecithin, with the largest increases in high hexane content samples. Equilibrium dialysis and component diffusion rate determination (by pulsed-field gradient [PFG]-NMR) indicated the quantity of water associated with the dispersed phase. Collectively, these methods demonstrated that a greater fraction of water was associated with the microemulsion-dispersed phase as the solvent was varied from DMEG to hexane. Iodine solubilization indicated microemulsion formation (operational critical micelle concentration [cmc], 10 moles water per mole lecithin) at approximately 10(-4)-10(-5) molal lecithin. NMR data (trimethylammonium proton chemical shift, water, and lecithin T1) were consistent with microemulsion formation. Water-soluble compounds dissolved in lecithin inverse microemulsions in a lecithin- and water-dependent manner. Experiments with DME/lecithin demonstrated microemulsion characteristics similar to those in the model propellant. DME/lecithin metered-dose inhalers (MDIs) produced a particle size and a fine particle fraction (36% by twin impinger method) suitable for pulmonary drug delivery.
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Affiliation(s)
- M L Sommerville
- School of Pharmacy, University of North Carolina, Chapel Hill 27514-7360, USA
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126
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Jiang YB, Jin MG. Intramolecular charge transfer at reverse micelle-water pool interface: p-N,N-dimethylaminobenzoic acid in AOT/cyclohexane/water reverse micelle. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000; 56:623-627. [PMID: 10794439 DOI: 10.1016/s1386-1425(99)00171-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Photoinduced intramolecular charge transfer (ICT) of p-N,N-dimethylaminobenzoic acid (DMABOA) in AOT/cyclohexane/H2O reverse micelle was investigated and compared with that in CTAB/1-heptanol/H2O reverse micelle. It is proposed that the DMABOA molecule exists at the AOT reverse micelle water pool interface with its carboxylic group heading toward the water pool while the dimethylaminophenyl moiety buried in the micellar phase. Dual fluorescence of DMABOA that is indicative of the ICT reaction in the excited state was observed over the investigated water pool size, W of 3-17, in the AOT reverse micelle. The ICT emission of DMABOA in the AOT reverse micelle-water pool interface was found to be much weaker than that in the CTAB reverse micelle-water pool interface, and was attributed to the parallel direction of the electric field at the AOT reverse micelle-water pool interface to the charge transfer.
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Affiliation(s)
- Y B Jiang
- Department of Chemistry and The SEDC Laboratory of Analytical Science for Material and Life Chemistry, Xiamen University, People's Republic of China.
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127
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Park HR, Lee HC, Kim TH, Lee JK, Yang K, Bark KM. Spectroscopic properties of fluoroquinolone antibiotics and nanosecond solvation dynamics in aerosol-OT reverse micelles. Photochem Photobiol 2000; 71:281-93. [PMID: 10732445 DOI: 10.1562/0031-8655(2000)071<0281:spofaa>2.0.co;2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Among fluoroquinolone antibiotics, ofloxacin (OFL) and norfloxacin (NOR) have piperazinyl groups but flumequine (FLU) does not have this substitutent. The emission spectra of OFL and NOR are strong, broad structureless bands with large Stokes' shifts in water but the emission intensities are very weak in organic solvents. Thus we find that these compounds exist as different chemical species in various solvents. A continuous red shift in the emission bands for OFL and NOR is observed as the water concentration within the aerosol-OT (AOT; sodium 1,4-bis[2-ethylhexyl]sulfosuccinate) micelle increases or temperature of this solution rises. From the fluorescence anisotropy measurements of OFL and NOR, we assume the intramolecular charge transfer after excitation from the nitrogen of the piperazinyl group to the keto oxygen. Theoretical calculations further support this observation. Multifrequency phase and modulation experiments and time-resolved emission spectra clearly show the occurrence of intramolecular charge transfer and the subsequent nanosecond water reorganization around OFL or NOR in the AOT micelle. Upon increasing the water concentration within the AOT micelle, the relaxation rate increases because of the large amount of free water. The emission spectra of FLU do not exhibit any significant response to the physical properties of their environment.
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Affiliation(s)
- H R Park
- Department of Chemistry, Chonnam National University, Kwangju, Korea
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128
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Faeder J, Ladanyi BM. Molecular Dynamics Simulations of the Interior of Aqueous Reverse Micelles. J Phys Chem B 2000. [DOI: 10.1021/jp993076u] [Citation(s) in RCA: 382] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Faeder
- Department of Chemistry, Colorado State University, Ft. Collins, Colorado 80523
| | - B. M. Ladanyi
- Department of Chemistry, Colorado State University, Ft. Collins, Colorado 80523
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129
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Caselli M, Daniele V, Mangone A, Paolillo P. Application of Multiple Linear Regression and Extended Principal-Component Analysis to Determination of the Acid Dissociation Constant of 7-Hydroxycoumarin in Water/AOT/Isooctane Reverse Micelles. J Colloid Interface Sci 2000; 221:173-180. [PMID: 10631017 DOI: 10.1006/jcis.1999.6584] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The apparent pK(a) of dyes in water-in-oil microemulsions depends on the charge of the acid and base forms of the buffers present in the water pool. Extended principal-component analysis allows the precise determination of the apparent pK(a) and of the spectra of the acid and base forms of the dye. Combination with multiple linear regression increases the precision. The pK(a) of 7-hydroxycoumarin (umbelliferone) was spectrophotometrically measured in a water/AOT/isooctane microemulsion in the presence of a series of buffers carrying different charges at various different water/surfactant ratios. The spectra of the acid and base forms of the dye in the microemulsion are very similar to those in bulk water in the presence of Tris and ammonia. The presence of carbonate changes somewhat the spectrum of the acid form. Results are discussed taking into account the profile of the electrostatic potential drop in the water pool and the possible partition of umbelliferone between the aqueous core and the surfactant. The pK(a) values corrected for these effects are independent of w(0) and are close to the value of the pK(a) in bulk water. Copyright 2000 Academic Press.
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Affiliation(s)
- M Caselli
- Dipartimento di Chimica, Università di Bari, via Orabona, 4, Bari, 70126, Italy
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130
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131
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Abstract
Water-in-oil microemulsions, or reverse micelles, are being evaluated as a reaction medium for a variety of enzymatic reactions. These systems have many potential biotechnological applications. Important examples are the use of various lipase microemulsion systems for hydrolytic or synthetic reactions. This review illustrates the biotechnological applications of microemulsions as media for bioorganic reactions. The principal focus is on lipase catalyzed processes.
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Affiliation(s)
- H Stamatis
- Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, 48, Vas. Constantinou Avenue, 11635 Athens, Greece
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132
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Garcia-Rio L, Mejuto JC, Ciri R, Blagoeva IB, Leis JR, Ruasse MF. Bromine−AOT Charge-Transfer Complexes and Hydrogen-Bond Donor Ability of Water in AOT−isooctane−H2O Reverse Micelles and Water-in-Oil Microemulsions. J Phys Chem B 1999. [DOI: 10.1021/jp982789u] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luis Garcia-Rio
- Institut de Topologie et de Dynamique des Systèmes (ITODYS), associé au CNRS - UPRES-A 7086, 1 rue Guy de la Brosse, 75005 Paris, France
| | - Juan C. Mejuto
- Institut de Topologie et de Dynamique des Systèmes (ITODYS), associé au CNRS - UPRES-A 7086, 1 rue Guy de la Brosse, 75005 Paris, France
| | - Renata Ciri
- Institut de Topologie et de Dynamique des Systèmes (ITODYS), associé au CNRS - UPRES-A 7086, 1 rue Guy de la Brosse, 75005 Paris, France
| | - Iva B. Blagoeva
- Institut de Topologie et de Dynamique des Systèmes (ITODYS), associé au CNRS - UPRES-A 7086, 1 rue Guy de la Brosse, 75005 Paris, France
| | - J. Ramon Leis
- Institut de Topologie et de Dynamique des Systèmes (ITODYS), associé au CNRS - UPRES-A 7086, 1 rue Guy de la Brosse, 75005 Paris, France
| | - Marie-Françoise Ruasse
- Institut de Topologie et de Dynamique des Systèmes (ITODYS), associé au CNRS - UPRES-A 7086, 1 rue Guy de la Brosse, 75005 Paris, France
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133
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Absorption and emission spectroscopic studies of fluorescein dye in alkanol, micellar and microemulsion media. J Photochem Photobiol A Chem 1999. [DOI: 10.1016/s1010-6030(99)00028-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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134
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Quaternary ‘N-alkylaldonamide-brine-decane-alcohol’ systems. Part II: microstructure of the one-phase microemulsion by NMR spectroscopy. Colloids Surf A Physicochem Eng Asp 1999. [DOI: 10.1016/s0927-7757(98)00704-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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135
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Correa NM, Durantini EN, Silber JJ. Binding of Nitrodiphenylamines to Reverse Micelles of AOT in n-Hexane and Carbon Tetrachloride: Solvent and Substituent Effects. J Colloid Interface Sci 1998; 208:96-103. [PMID: 9820753 DOI: 10.1006/jcis.1998.5842] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The absorption spectra of N-[2-(trifluoromethyl)-4-nitrophenyl]-4-nitroaniline (1), N-[4-nitrophenyl]-4-nitroaniline (2), and N-[2-nitrophenyl]-4-nitroaniline (3) were analyzed in reversed micelles of AOT (sodium 1,4-bis (2-ethylhexyl sulfosuccinate) in n-hexane and carbon tetrachloride. For 1 and 2 the intensity of the band characteristic for the pure solvent decreases as the AOT concentration increases and a new band develops. This new band is attributed to the solute bound to the micelle. These changes allowed us to determine the binding constant (Kb) between these compounds and AOT. Kb at W0 = [H2O]/[AOT] = 0 in n-hexane varies from 81 for 1 to 5092 for 2. Although similar trends are observed for carbon tetrachloride, the values of Kb are smaller than those for n-hexane. The possible solute-solvent interactions of these compounds were analyzed by means of Taft and Kamlet's solvatochromic comparison method. The strength of binding is interpreted considering their hydrogen-bond donor ability as well as their solubility in the pure solvents. For 1 Kb decreases as W0 is increased, while for 2 no variation was observed. These effects are discussed in terms of nitrodiphenylamine-water competition for interfacial binding sites. Moreover, the effect of the solute size and the presence of the trifluoromethyl group in 1 are important factors to consider in explaining its binding behavior. The spectra of 3 change very little with AOT concentration and only a slight bathochromic shift is observed. Thus, 3 acts as nonhydrogen bond donor solute, merely sensing a slight change in the polarity of its microenvironment. Copyright 1998 Academic Press.
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Affiliation(s)
- NM Correa
- Departamento de Química y Física, Universidad Nacional de Río Cuarto, Agencia Postal Nro 3, Río Cuarto 5800, Argentina
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136
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137
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Kozlovich N, Puzenko A, Alexandrov Y, Feldman Y. Effect of charge density fluctuations within a droplet on dielectric polarization of ionic microemulsions. Colloids Surf A Physicochem Eng Asp 1998. [DOI: 10.1016/s0927-7757(97)00287-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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138
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Grand D. Electron Transfer in Reverse Micellar Solutions: Influence of the Interfacial Bound Water. J Phys Chem B 1998. [DOI: 10.1021/jp9724840] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. Grand
- U.R.A.75, C.N.R.S., Université de Paris-Sud, 91 405 Orsay Cedex, France
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139
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Li Q, Weng S, Wu J, Zhou N. Comparative Study on Structure of Solubilized Water in Reversed Micelles. 1. FT-IR Spectroscopic Evidence of Water/AOT/n-Heptane and Water/NaDEHP/n-Heptane Systems. J Phys Chem B 1998. [DOI: 10.1021/jp972254l] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Quan Li
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Shifu Weng
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jinguang Wu
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Naifu Zhou
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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140
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Riter RE, Willard DM, Levinger NE. Water Immobilization at Surfactant Interfaces in Reverse Micelles. J Phys Chem B 1998. [DOI: 10.1021/jp973330n] [Citation(s) in RCA: 259] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruth E. Riter
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872
| | - Dale M. Willard
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872
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141
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Wang C, Liu C, Wang Y, Shen T. Spectral Characteristics and Photosensitization Effect on TiO2 of Fluorescein in AOT Reversed Micelles. J Colloid Interface Sci 1998; 197:126-32. [PMID: 9466852 DOI: 10.1006/jcis.1997.5235] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The microenvironment in reverse micelles composed of water, aerosol OT (AOT, sodium bis(2-ethylhexyl)sulfosuccinate), and isooctane has an important effect on the spectral properties of fluorescein (FL). The absorption peaks of FL red-shifted by about 10 nm from the corresponding positions in aqueous solution. Moreover, the absorption extinction coefficient of FL in reversed micelles increased with the water content, omega. The fluorescence of FL was more effectively quenched in AOT reversed micelles than in aqueous solution. In addition, aggregation occurred for FL in reversed micelles, which hindered the photo-induced electron transfer from the excited singlet of FL to the conduction band of TiO2. Copyright 1998 Academic Press. Copyright 1998Academic Press
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Affiliation(s)
- Cy Wang
- Institute of Photographic Chemistry, Academia Sinica, Beijing, 100101, People's Republic of China
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142
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Adhikari S, Joshi R, Gopinathan C. Reaction kinetics of hydrated electrons in a quaternary micro emulsion system: A pulse radiolysis study. INT J CHEM KINET 1998. [DOI: 10.1002/(sici)1097-4601(1998)30:10<699::aid-kin1>3.0.co;2-q] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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143
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Rabie HR, Vera JH. Counterion Binding to Ionic Reverse Micellar Aggregates and Its Effect on Water Uptake. J Phys Chem B 1997. [DOI: 10.1021/jp9631036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hamid R. Rabie
- Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada H3A 2A7
| | - Juan H. Vera
- Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada H3A 2A7
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144
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Ramírez-Silva L, Oria J, Gómez-Puyou A, Tuena de Gómez-Puyou M. The contribution of water to the selectivity of pyruvate kinase for Na+ and K+. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 250:583-9. [PMID: 9428713 DOI: 10.1111/j.1432-1033.1997.0583a.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
For many years it has been known that K+ is an essential activator of pyruvate kinase [Kachmar, J. F. & Boyer, P. D. (1953) J. Biol. Chem. 200, 669-683] and that Na+ induces relatively small enhancements of activity. The effect of these two alkali metal ions on the activity of pyruvate kinase entrapped in the low water environment of reverse 'micelles formed with cetyltrimethylammonium, hexanol, n-octane and various water concentrations was studied. In reverse micelles with 3.6% water, the activity with 7 mM Na+ is more than 82 times higher than in aqueous solution with an equivalent Na+ concentration. As the concentration of water in reverse micelles is raised, the activating effect of relatively low concentrations of Na+ (or K+) decreases simultaneously to a more than 100-fold increase in the concentration of Na+ or K+ required for attaining half-maximal activation. Similar results were obtained with NH4+, Rb+ and Cs+. Therefore, the amount of water in the system is critical for observing activation by alkali metal ions. In fact, the concentration of Na+ required for half-maximal activation in standard aqueous media is higher than the concentrations that can be experimentally assayed. As evidenced from fluorescence and kinetic data, it appears that the entrapment of pyruvate kinase in reverse micelles does not produce gross structural alterations. Therefore, it is suggested that in conventional aqueous systems, the basis of the high discrimination between Na+ and K+ by pyruvate kinase is the higher energy required for desolvating Na+. Nevertheless, at all the water concentrations studied, the activities reached with K+ were higher than with Na+ which suggests that the Na+ form of the enzyme has a lower catalytic capacity than the K+-enzyme complex.
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Affiliation(s)
- L Ramírez-Silva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México., México, DF
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145
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On the bicontinuous microstructure induced by a guest protein in a typical AOT microemulsion. Colloids Surf A Physicochem Eng Asp 1997. [DOI: 10.1016/s0927-7757(97)00050-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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146
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Heitz MP, Carlier C, deGrazia J, Harrison KL, Johnston KP, Randolph TW, Bright FV. Water Core within Perfluoropolyether-Based Microemulsions Formed in Supercritical Carbon Dioxide. J Phys Chem B 1997. [DOI: 10.1021/jp9622243] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mark P. Heitz
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Claude Carlier
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Janet deGrazia
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Kristi L. Harrison
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Keith P. Johnston
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Theodore W. Randolph
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Frank V. Bright
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
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147
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Luminescence behaviour of phenosafranin in reverse micelles of AOT in n-heptane. J Photochem Photobiol A Chem 1997. [DOI: 10.1016/s1010-6030(97)00091-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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148
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149
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García-Río L, Leis JR, Reigosa C. Reactivity of Typical Solvolytic Reactions in SDS and TTABr Water-in-Oil Microemulsions. J Phys Chem B 1997. [DOI: 10.1021/jp970460n] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L. García-Río
- Departamento de Química Física, Facultad de Química, Universidad de Santiago, 15706 Santiago de Compostela, Spain
| | - J. R. Leis
- Departamento de Química Física, Facultad de Química, Universidad de Santiago, 15706 Santiago de Compostela, Spain
| | - C. Reigosa
- Departamento de Química Física, Facultad de Química, Universidad de Santiago, 15706 Santiago de Compostela, Spain
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150
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Lee DK, Kim YI, Kwon YS, Kang YS, Kevan L. Electron Magnetic Resonance Study of the Photoreduction of Alkylviologens in Anionic Sodium Dodecyl Sulfate and Cationic Dodecyltrimethylammonium Bromide Micelles. J Phys Chem B 1997. [DOI: 10.1021/jp962221q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Don Keun Lee
- Department of Chemistry, Pukyung National University, Pusan 608-737, Korea
| | - Yeong Il Kim
- Department of Chemistry, Pukyung National University, Pusan 608-737, Korea
| | - Young Soo Kwon
- Department of Chemistry, Pukyung National University, Pusan 608-737, Korea
| | - Young Soo Kang
- Department of Chemistry, Pukyung National University, Pusan 608-737, Korea
| | - Larry Kevan
- Department of Chemistry, University of Houston, Houston, Texas 77204-5641
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