CHARACTERIZING LIPOSOMES FORMED BY MIXTURES OF DPPC OR DODAC W/SUCROSE ESTERS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Sucrose esters correspond to a class of non ionic surfactants, non-toxic, skin compatible, non-polluting and biodegradable. Also, their synthesis is not dependent of petrochemical industry and they can be prepared from renewable sources. In addition, the surface-activity described for commercial mixtures of sucrose esters is similar to that of alkyl glucosides, a family of surfactants recurrently employed in membrane solubilization studies. In consequence, sucrose esters are attractive candidates for the study of its interactions with membranes, synthetic and biological. The primary objective of this work was therefore to assess the feasibility of using solubilization experiments to study the interactions of nonionic surfactants with cholesterol-containing phospholipid vesicles. Conventional fluorescence techniques and two-photon microscopy were used, with Laurdan, as a fluorescent probe, because its ability to sense changes in the polarity of its microenvironment. This time we are interested in the direct observation of the changes promoted in the GP of GUVS by the incorporation and subsequent solubilization of DODAC vesicles by the addition of several sucrose esters. Additionally FCS experiments will be carried out in order to determine critical micellar concentrations of several sucrose monoesters, and the dependence of aggregation numbers with concentration.