Co-solubilization

Oriented membrane samples were prepared by depositing peptide-lipid mixtures (co-solubilized in CHCls/MeOH 2 1, v/v) on glass slides (0.08x 7.5 x 18 mm, Paul Marienfeld KG, Mergentheim, Germany). Drops of 20-30 xL... 

Using this principle, light induced charge separation has been achieved for a number of donor/acceptor pairs. Noteworthy are the examples where pyrene served as an electron acceptor and dimethyl aniline as a donor as well as the photoinduced reduction of duroquinone by chlorophyll-a. Experimental data obtained for the latter system are presented in Fig. 4.6. The upper two traces represent absorption versus time curves from micellar solutions containing chl-a alone. They reflect formation and decay of chl-a triplet states. The time course of both the 685 and 465 nm absorption is drastically affected when DQ is co-solubilized with chl-a in the micelles. In particular, a long-term bleaching of chl-a absorption is noted which can be attributed to chl-a+ cation radical formation via ... 

Table 5.23 Summary of observations on systems containing co-solubilized materials [164].

Formulae have been assembled for multi-vitamin syrup and multi-vitamin drops [190, 191] using polysorbate 80 to solubilize vitamin A palmitate and vitamin D with glycerin as co-solubilizer, enabling a high concentration of drug to be given per dose. The solubilizer serves the extra purpose of allowing the preparations to be diluted into water or milk for paediatric administration. The sorbitol, primarily added to enhance the taste of the preparation, but which increases the absorption of vitamin Bj2, obviously also acts as a co-solubilizer [192]. A similar preparation is described by Whittet and Cummins [193]. 

Formation of microemulsions is encouraged by the addition of a co-solubilizer such as a long-chain alcohol, possibly because of the geometric requirements for the appropriate curvature in the interfacial region. The stability and structure of microemulsion particles is still a subject of debate [167, 171]. 

The ionization by light at 347.1 nm (3.57 eV energy) of phenothiazine incorporated in NaLS micelles in water has been attributed to the rapid tunnelling of an electron from excited phenothiazine through the double layer into unoccupied electronic redox levels of the system aq/cj [57]. This photoionization is promoted by co-solubilization of duroquinone which prevents ejection of electrons from the phenothiazine into the water phase. It is suggested [57] that the phenothiazine/water/quinone/micelle system offers a simple model for electron transfer in photosynthetic systems and for the heterogeneous catalysis of the photodecomposition of water via the freed electrons. A schematic representation of the processes when the surfactant is anionic [58] is shown in Fig. 11.10. 

When polymerizable monomers are solubilized in surfactant micelles it should be possible to produce polymerized micelles containing co-solubilized drug. The process has been successfully achieved by Speiser [186]. Fig. 11.29 represents an inverse micelle containing a water-soluble drug in which the monomeric species is located in the outer part of the micelle and is cross-linked to form a "nanocapsule ... 

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