Effects of protein solubilization on the structure of the surfactant shell of reverse micelles

Zuev, Yu. F.; Vylegzhanina, N. N.; Zakhartchenko, N. L.

doi:10.1007/bf03166964

Cited by 20 publications

(17 citation statements)

References 26 publications

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“…The A N = (A xx + A yy + A zz )/3 parameter increases with the increase of the environmental polarity of the probe. The S-parameter is a measure of the degree of ordering of the surfactant molecules in these regions [53].…”

Section: Epr Resultsmentioning

confidence: 99%

Do food microemulsions and dietary mixed micelles interact?

Rozner¹,

Shalev²,

Shames³

et al. 2010

Colloids and Surfaces B: Biointerfaces

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Section: Epr Resultsmentioning

confidence: 99%

Do food microemulsions and dietary mixed micelles interact?

Rozner¹,

Shalev²,

Shames³

et al. 2010

Colloids and Surfaces B: Biointerfaces

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“…The procedure for introducing spin probes into the micel lar solutions, the conditions for registration of ESR spectra, and methods of their analysis are described elsewhere. 20, 21 The self diffusion coefficients of surfactants were measured by 1 H NMR spectroscopy with Fourier transform and pulsed magnetic field gradient. 22 A Tesla BS 587 NMR spectrometer equipped with a gradient accessory for production of magnet ic field gradients up to 0.5 T m -1 was used.…”

Section: Methodsmentioning

confidence: 99%

Mixed micellar systems of geminal alkylammonium surfactants and long-chain amines

et al. 2010

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Numerical characteristics of the aggregation behavior of geminal alkylammonium surfac tants in aqueous solutions (the size of micelles, the packing of surfactant molecules, the surface potential, the extent of counterion binding) were determined. The formation of mixed micelles geminal surfactant/decylamine resulted in substantial decrease in amine pK a ; this is the crucial factor determining the strong catalytic effect of the system in ester bond cleavage processes.The most important feature of aqueous micellar solu tions of surfactants is the capability of solubilization of reactive substances possessing different hydrophilic lipo philic properties; this substantially extends the possibility of their use as reaction media. 1-4 Transfer of the reactants from the bulk of solvent to the micellar pseudophase is accompanied by changes in their microenvironment, which in turn leads to changes in the reactivity, acid base properties, spectral, and other physicochemical parame ters. The most pronounced changes are observed for am phiphilic reagents (long chain aliphatic amines, alkylphe nols), 5-7 which can form mixed micelles with surfactants, containing functional groups sensitive to variation of pH values of the media and the component ratio.In the last decade, interest in the geminal (dimeric) surfactants and highly organized systems based on them increased sharply. Geminal surfactants contain two hy drophobic radicals and two head (usually, charged) groups linked by spacers with different rigidity. These compounds differ from their amphiphilic analogs containing only one head group and one hydrocarbon chain by lower values of the critical micelle concentration (CMC), high surface activity, and solubilizing action; they are also character ized by unusual morphological behavior. 8-11 A series of papers devoted to the study of the aggregation behaviour and the structural properties of geminal surfactants were published. 12-14 A number of studies 15-18 on the catalytic effect of micellar solutions of these compounds in the nucleophilic substitution reactions were reported.The present work is dedicated to elucidation of the possibility of using aqueous solutions of geminal cationic surfactants as media for reactions involving hydrophobic alkylamines. Taking n decylamine as an example, data on the solubilizing effect, aggregation properties, and cata lytic activity in ester bonds cleavage of two geminal alkyl ammonium surfactants with different length of hydropho bic fragments six methylene unit spacers [C 12 H 25 (CH 3 ) 2 N(CH 2 ) 6 N(CH 3 ) 2 C 12 H 25 ] 2+ •2Br -(Gem 12), [C 16 H 33 (CH 3 ) 2 N(CH 2 ) 6 N(CH 3 ) 2 C 16 H 33 ] 2+ •2Br - (Gem 16) were obtained.A comparative analysis of their properties and those of analogous monomeric cationic surfactants, dodecyltri methylammonium bromide (DdTAB) and cetyltrimethyl ammonium bromide (CTAB), was carried out. ExperimentalCommercially available CTAB and DdTAB (Sigma), n de cylamine, n octylamine, and also p nitrophenyl acetate (PNPA) (Fluka) with 99% purity were us...

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“…By using purposely tailored molecular probes, the EPR technique has proved to provide detailed information on the structure and dynamics of micelles [ 27 ], polymer–surfactant aggregates [ 28 ] and vesicles [ 29 ]. It has also been used to analyze the properties of surfactants layers adsorbed at the solid/liquid and liquid/liquid interfaces, as in emulsions, microemulsions [ 30 , 31 , 32 , 33 , 34 , 35 ], nanoemulsions [ 7 ] and reversed micelles [ 36 , 37 ]. Specifically, in the present study we characterize by EPR the Span80/Tween80 layer interposing between water and oil domains by using two amphiphilic spin-labeled fatty acids, 5- and 16-doxyl stearic acids (abbreviated as 5- and 16-DSA, respectively).…”

Section: Introductionmentioning

confidence: 99%

Phase Inversion and Interfacial Layer Microstructure in Emulsions Stabilized by Glycosurfactant Mixtures

et al. 2021

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Identification of strategies to prolong emulsion kinetic stability is a fundamental challenge for many scientists and technologists. We investigated the relationship between the emulsion stability and the surfactant supramolecular organization at the oil–water interface. The pseudo-phase diagrams of emulsions formed by water and, alternatively, a linear or a branched oil, stabilized by mixtures of two sugar-based surfactants, Span80 and Tween80, are presented. The surfactant ordering and dynamics were analyzed by electron paramagnetic resonance (EPR) spectroscopy. In Oil-in-Water (O/W) emulsions, which are stable for more than four days, disordered surfactant tails formed a compact and viscous layer. In Water-in-Oil (W/O) emulsions, whose stability is much lower, surfactants formed an ordered layer of extended tails pointing toward the continuous apolar medium. If linear oil was used, a narrow range of surfactant mixture composition existed, in which emulsions did not demix in the whole range of water/oil ratio, thus making it possible to study the phase inversion from O/W to W/O structures. While conductometry showed an abrupt inversion occurring at a well-defined water/oil ratio, the surfactant layer microstructure changed gradually between the two limiting situations. Overall, our results demonstrate the interconnection between the emulsion stability and the surfactant layer microstructuring, thus indicating directions for their rational design.

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Effects of protein solubilization on the structure of the surfactant shell of reverse micelles

Cited by 20 publications

References 26 publications

Do food microemulsions and dietary mixed micelles interact?

Do food microemulsions and dietary mixed micelles interact?

Mixed micellar systems of geminal alkylammonium surfactants and long-chain amines

Phase Inversion and Interfacial Layer Microstructure in Emulsions Stabilized by Glycosurfactant Mixtures

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