Main phase transition depression by incorporation of alkanols in DPPC vesicles in the gel state: Influence of the solute topology

Diphenylhexatriene is employed to sense the changes elicited in dipalmitoylphosphatidylcholine large unilamellar vesicles by the incorporation of several alkanols. From the dependence of the observed anisotropy values upon the surfactant concentration, pseudo partition constants of alkanols are obtained under conditions in which the vesicles are intermediate between the gel and liquid crystalline states. These data, together with previous data obtained at lower alkanol concentrations, allow an evaluation of the dependence of the alkanol incorporation on the solute concentration. The effect of the solute topology is investigated by employing linear and highly branched alkanols.