Solubilization in Micelles and Vesicles Studied by Fluorescence Techniques: Interplay Between the Microproperties of the Aggregates and the Locus and Extent of Solubilization
An overview of fluorescence techniques and methodologies that are commonly employed in studies of solubilization in micellar and vesicular solutions 298is presented in this chapter. Three aspects of solubilization are the main topics to be treated in detail: the solubilization extent, the solubilization loci, and the effect that the solubilizate can exert upon properties of the microaggregates. The first part deals with the evaluation of partition coefficients. Methods useful to obtain partitioning data pertaining to fluor-ophores, fluorescence quenchers, and additives that are nonquenchers but modify a fluorescence characteristic are described and their potential and limitations are discussed. The second part is devoted to analyzing how fluorescence measurements can be employed to monitor the characteristics of the microenvironment of solutes incorporated to micelles and vesicles and how the properties of the aggregate are modified by the presence of the solute. The interplay between solubilization and microaggregate properties is discussed, with special emphasis in cosolubilization extent, dependence of partition coefficients with solute concentration, and the changes in the fluorescence characteristics of fluorophores elicited by cosolute incorporation.