Micelles internal organization

Guetzlhoff TF, Rice JA (1992) Does humic acid form a micelle . International Conference on Organic Substances in Soils and Sediments, Lan-chester, UK... 

Defining inside from outside is a fundamental trait of living organisms. The creation of noimamral strucmres that can define in from out with nonpermeable or semipermeable barriers offers the potential of protecting the internal content from destmction, contamination, and unwanted dispersal until the content is dehvered to a defined location. Small spherical structures that define in and out are well known and come in forms ranging from microcapsules to vesicles to micelles. We refer to these structures collectively as polymeric capsules. 

Water in oil microemulsions with reverse micelles provide an interesting alternative to normal organic solvents in enzyme catalysis with hydrophobic substrates. Reverse micelles are useful microreactors because they can host proteins like enzymes. Catalytic reactions with water insoluble substrates can occur at the large internal water-oil interface inside the microemulsion. The activity and stability of biomolecules can be controlled, mainly by the concentration of water in these media. With the exact knowledge of the phase behaviom" and the corresponding activity of enzymes the application of these media can lead to favomable effects compared to aqueous systems, like hyperactivity or increased stability of the enzymes. 

Thus the boundaries of the enclosures in organized media may be of two types they may be stiff (i.e, none of the guest molecules can diffuse out and the walls do not bend), as in the case of crystals and some inclusion complexes, or flexible (i.e., some of the guest molecules may exit the cavity and the walls of the cavity are sufficiently mobile to allow considerable internal motion of the enclosed molecules), as in the case of micelles and liquid crystals. In these two extremes, free volume needed for a reaction is intrinsic (built into the reaction cavity) and latent (can be provided on demand). 

Internal Phase Composition As with the continuous phase, the internal phase properties also influence the properties of the ELM. Ionic strength, pH, and the presence of organic species will impact on the stability of the ELM. Emulsion liquid membranes work on the basis that the polar substances (usually high concentrations of acid or base) contained in the internal phase are impermeable to the membrane phase. However, the presence of the surfactant can cause the uptake of these compounds by the formation of reverse micelles [97]. 

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