Dodecyltrimethylammonium bromide in water-urea mixtures: structure and energetics

Caponetti, E.; Causi, S.; Lisi, R. De; Floriano, Michele; Milioto, Stefana; Triolo, R.

doi:10.1021/j100191a042

Cited by 38 publications

(28 citation statements)

References 13 publications

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“…Among them can be mentioned the increase in the solvent dielectric constant of the medium (34) (indirect mechanism of urea action) and the replacement of water by urea at the surfactant heads (direct mechanism of urea action), with a concomitant decrease in the magnitude of the short range forces that control the specific interactions. The combination of these effects could also explain the increase in the degree of counterions dissociation associated to the presence of urea both in cationic (7,8,17) and anionic (5) micelles. Furthermore, a decrease in the structure of water associated to the presence of urea could also contribute to the decrease in selectivity, particularly when hydrophobic FIG.…”

Section: Exchange At the Surface Of Sds Micelles In Water-urea Mixturmentioning

confidence: 99%

“…Miyaghisi et al (11) performed a study of proteins (15) and alters several properties of micellar of the alteration in properties of micelles induced by pertursolutions: (A) it increases the critical micelle concentration bation in the external environment and used urea as an addiof ionic (1,5,7,9) and nonionic (1,2,6,9) surfactants; tive assumed to be unable to penetrate the micelles. Simi-(B) it decreases the micellar size of ionic (8,14) and non-larly, urea was assumed to be a nonpenetrating agent in a ionic (6) surfactants; (C) it increases the counterion dissoci-study performed by Gonzalez et al (12) regarding the effect ation degree of ionic micelles (5,7,8); (D) it increases the of additives on the solubility of naphthalene derivatives in cloud point of nonionic (2,6) and decreases the cloud point micellar solutions. Alternatively, results from recent studies of zwitterionic (10) surfactants; (E) it increases the local have been interpreted to favor a direct mechanism of urea viscosity and decreases the local polarity at the micellar action upon properties of micelles.…”

Section: Introductionmentioning

confidence: 99%

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Tl+/Na+Competitive Binding at the Surface of Dodecylsulfate Micelles in Water–Urea Mixtures

Abuín

Lissi

Borsarelli

1996

Journal of Colloid and Interface Science

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Section: Exchange At the Surface Of Sds Micelles In Water-urea Mixturmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tl+/Na+Competitive Binding at the Surface of Dodecylsulfate Micelles in Water–Urea Mixtures

Abuín

Lissi

Borsarelli

1996

Journal of Colloid and Interface Science

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“…A large list of N agg values has been reported for the studied systems under different conditions (Table S1), ,− principally for C 12 TAB (Figure ). These values exhibit a significant discrepancy that is mainly due to the concentration where they have been measured.…”

Section: Resultsmentioning

confidence: 99%

Simple ApproximaTion for Aggregation Number Determination by Isothermal Titration Calorimetry: STAND-ITC

et al. 2021

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A new proposal to obtain aggregation numbers from isothermal titration calorimetry dilution experiments is described and tested using dodecyl trimethyl ammonium bromide, dodecyl methylimidazolium chloride, dodecyl methylimidazolium sulfonate, and didecyl methylimidazolium chloride aqueous solutions at different temperatures. The results were compared to those obtained from fluorescence measurements and also with data from the literature. In addition to the aggregation number, the molar free energy to transfer a solute molecule from the aggregate to the bulk solution, the enthalpy corresponding to the formation of the self-assembled suprastructures, the molar heat corresponding to the dilution of monomers and aggregates, and an offset parameter to account for unpredictable external contributions are simultaneously obtained using the same method. The new equations are compared to those obtained from previous proposals, and they are also analyzed in detail to assess the impact of each fitting parameter in the profile of the calorimetric isotherm. This new approach has been implemented in a computational code that automatically determines the fitting parameters as well as the corresponding statistical uncertainties for the large variety of calorimetric profiles that have been tested. Given the high sensitivity of the dilution experiments to the aggregation number for relatively small assemblies, our approach is proposed also to quantify the oligomerization state of biomolecules such as proteins and peptides.

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“… 5 , 6 The presence of an additive modifies various aggregating properties of the micellar solution of surfactant. 7 − 11 Urea, a well-known protein denaturant, with ionic and nonionic surfactants increases the critical micellar concentration (cmc) values, 12 − 16 reduces the aggregation number of micelles, 17 , 18 etc. The solubility of hydrocarbons in aqueous medium is enhanced in the presence of urea.…”

Section: Introductionmentioning

confidence: 99%

“…Micelles, the assemblies of surfactant molecules, up to certain extent mimic the environment of lipid bilayers. The studies on micellar organization and dynamics are paid special attention because the general principle for the micelles formation is related to other molecular assemblies, such as bilayers, reverse micelles, liposomes, and biological membrane. − For biophysical or structure biological studies, surfactants are used to maintain the purified protein in its native and functional states. , The presence of an additive modifies various aggregating properties of the micellar solution of surfactant. − Urea, a well-known protein denaturant, with ionic and nonionic surfactants increases the critical micellar concentration (cmc) values, − reduces the aggregation number of micelles, , etc. The solubility of hydrocarbons in aqueous medium is enhanced in the presence of urea.…”

Section: Introductionmentioning

confidence: 99%

Effect of Urea on Solvation Dynamics and Rotational Relaxation of Coumarin 480 in Aqueous Micelles of Cationic Gemini Surfactants with Different Spacer Groups

et al. 2018

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The present work highlights the effect of urea on solvation dynamics and the rotational relaxation of Coumarin 480 (C-480) in the Stern layer of aqueous micelles of cationic gemini surfactants, 12-4(OH)n-12 (n = 0, 1, 2). UV–visible absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, and dynamic light scattering measurements have been carried out for this study. The formation of micelles becomes disfavored in the presence of urea at high concentration. Solvation dynamics is bimodal in nature with fast solvation as a major component. The average solvation time increases, reaches a maximum, and then decreases with increasing concentration of urea because the degree of counterion dissociation also follows the same order with the addition of urea in the micellar solution. With increased degree of counterion dissociation, the extent of clustering of water molecules is increased, resulting in slower solvation process. The −OH group present in the spacer group of gemini surfactant controls the rate of solvation by shielding the water molecules from the probe molecules forming hydrogen bond. The microviscosity of micelles is decreased with increasing concentration of urea, as a result of which the rotational relaxation process becomes faster. In the presence of the −OH group in the spacer group, the microviscosity of micelles is enhanced, resulting in longer rotational relaxation time. Rotational relaxation process is bimodal in nature with the major contribution from the fast component to the fluorescence depolarization. Slow rotational relaxation is mainly due to the lateral diffusion of C-480 molecules along the surface of the micelle. The tumbling motion of the micelle as a whole is much slower than the lateral diffusion of C-480. Wobbling motion of C-480 becomes faster with increasing concentration of urea as a result of decreased microviscosity of micelles. The alignment of C-480 molecules in micelles might change with changing microviscosity.

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Dodecyltrimethylammonium bromide in water-urea mixtures: structure and energetics

Cited by 38 publications

References 13 publications

Tl+/Na+Competitive Binding at the Surface of Dodecylsulfate Micelles in Water–Urea Mixtures

Tl+/Na+Competitive Binding at the Surface of Dodecylsulfate Micelles in Water–Urea Mixtures

Simple ApproximaTion for Aggregation Number Determination by Isothermal Titration Calorimetry: STAND-ITC

Effect of Urea on Solvation Dynamics and Rotational Relaxation of Coumarin 480 in Aqueous Micelles of Cationic Gemini Surfactants with Different Spacer Groups

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