Micelles dynamic properties

E. Faetibold, G. Waton. Dynamical properties of wormlike micelles in the vicinity of the crossover between dilute and semidilute regimes. Langmuir 77 1972-1979, 1995. 

A. Structural and Dynamic Properties of Water-Containing Reversed Micelles... 

As a result of their size and of specific interactions, hydrophilic macromolecules or solid nanoparticles cause strong changes in micellar size and dynamics, and their structural and dynamic properties are strongly affected. In these cases, the distribution among reversed micelles can be only described by ad hoc models [13,123]. 

As a result of the micellar environment, enzymes and proteins acquire novel conformational and/or dynamic properties, which has led to an interesting research perspective from both the biophysical and the biotechnological points of view [173-175], From the comparison of some properties of catalase and horseradish peroxidase solubilized in wa-ter/AOT/n-heptane microemulsions with those in an aqueous solution of AOT it was ascertained that the secondary structure of catalase significantly changes in the presence of an aqueous micellar solution of AOT, whereas in AOT/n-heptane reverse micelles it does not change. On the other hand, AOT has no effect on horseradish peroxidase in aqueous solution, whereas slight changes in the secondary structure of horseradish peroxidase in AOT/n-heptane reverse micelles occur [176],... 

Molecules that possess both hydrophilic and hydrophobic structures may associate in aqueous media to form dynamic aggregates, commonly known as micelles. The properties of micellar structures have been discussed in great detail [66-69], but thejr main pharmaceutical application lies in their ability to provide enhanced solubility to compounds lacking sufficient aqueous solubility [70], The ability of a micelle to solubilize compounds of limited aqueous solubility can be understood from consideration of the schematic drawing of Fig. 10a. Above the critical micelle concentration, these molecules orient themselves with the polar ends in interfacing with the aqueous solution and the nonpolar ends at the interior. A hydrophobic core is formed at the interior of the micelle, and hydrophobic solute molecules enter and occupy this region. 

Figure 9.10 Some structural details and dynamic properties of reverse micelles 50 irtM AOT/isooctane, Wo = 11.1 (= 10 p lHoOperml), 25°C 3.2% AOT (w/w), 1.4% H2O (w/w) mean water pool radius 20 A, mean hydrohynamic radius 32 A concentration of micelles 400 (xM, monomer AOT concentration 0.6-0.9 mM aggregation number 125 total interfacial area 14 m mC (Adapted from Fletcher and Robinson, 1981, and Harada and Schelly, 1982.)...

Schurtenberger, P, Scartazzini, R., Magid, L. J., Leser, M. E., and Luisi, P. L. (1990). Structural and dynamic properties of polymer-like reverse micelles. /. Phys. Chem., 94, 3695-701. 

Fluorescent probes in reversed micellar aggregates proved, moreover, appropriate to study dynamic properties of micelles in nonpolar solvents42,44 The particularly suitable fluorescent label was the highly water sensitive terbium ion (Tb3+) (Fig. 26). 

It is reasonable and widely accepted that the back-transfer process of proteins and other solutes is governed by an interfacial process and by a coalescence of the reverse micelles at the oil-water interface. According to the previous report, alcohol promotes the fusion/fission of the reverse micelles [11]. Such a modification in the dynamic property of reverse micellar droplets also affects the coalescence of the droplets and the bulk aqueous solution, and in this study results in an assistance in the release of proteins from the droplets. However, besides the alcohol addition, the appropriate pH and salt concentration in the recovery aqueous phase is required for protein release from the droplets into the recovery phase. The salt concentration leads to an osmotic effect and results in a swelling of the droplets in the presence of alcohol. The swelling droplets would... 

K. Suga, K. Maemura, M. Fujihira, and S. Aoyagui, ESR studies ofthe dynamic properties of ion radicals captured by surfactant micelles, Bull Chem. Soc. Jpn. 60, 2221-2226 (1987). 

The structural and dynamical properties of micelles have been investigated by many groups, using different approaches such as continuum models and lattice models -" and using atom-atom potentials without s,79 and with explicit solvent molecules. " All these models have helped in furthering our understanding of micelle structure and dynamics. 

In Figure 16.12 the morphology of the Hf phase is compared with that of the Hn phase formed from SAINT-2 and DOPE. A similar Hf phase has previously been reported for lipoplexes composed of the single-tailed, micelle-forming snrfactant CTAB. In this phase the amphiphile monomers are dynamic and able to move in and out of the micelles. These properties allow translocation of endosomal lipids into the lipoplex thereby stimn-lating release of DNA into the cytosol. 

Experimental evidence shows that quite often solutions of giant micelles posses static and dynamic properties analogous to those of macromolecules [108,192]. Their primary structure is both unidimensional and flexible. In the dilute regime, giant micelles are characterized by nonuniform size distribution, which is strongly influenced by experimental conditions [108]. At higher concentrations, in the semidilute regime, the main differences between micelles and polymer solutions vanish [108]. 

Lequeux E, Candau SJ. Dynamical properties of wormlike micelles deviations from the classical picture. In Herb CA, Prud homme RK, eds. Structure and Flow in Surfactant Solutions. Washington, DC American Chemical Society, 1994 51-62. 

Besides their practical interest in today s life, giant micelles are attractive, notably because of the accurate knowledge of their phase behavior and dynamical properties, the simplicity of their linear response, and their analogy with conventional polymers. The major interest comes from the large diversity of their flow behaviors that continue to fascinate lots of experimentalists and theoreticians, especially because they are representative of many phenomena encountered in other complex fluids. 

Lequeux F, Candau S (1994) Dynamical properties of wormlike micelles. In Herb C, Prud homme R (eds) Structure and flow in surfactant solutions. ACS Symposium Series 578. American Chemical Society, Washington, DC, pp 51-62... 

Dynamic Properties of Higher-Order Unimer Micelles. 

Chelushkin PS et al (2008) Polyion complex nanomaterials from block polyelectrolyte micelles and linear polyelectrolytes of opposite charge. 2. Dynamic properties. J Phys ChemB 112 7732-7738. doi 10.1021/jp8012877... 

In the next sections results are reported on the dynamics of large aggregates consisting of small surfactant molecules, i.e. lamellar microemulsion phases and of micelles of block-coploymer molecules illustrating the separation of different scattering contributions by their dynamical properties. 

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