Liposomal Membranes. XVIII. Interaction of Spermicidal Agents with Liposomal Membranes

Abstract

The release of a water soluble material, carboxyfluorescein (CF), from the interior of liposomes induced by several spermicidal agents, nonionic surfactants (TS-88, INP-90, and NOP-90), has been investigated. The efficiency of the agents for CF-release was significantly correlated with that for the inhibition of fertilizing ability of sea urchin sperm (p<0.01). On the other hand, it was also found that these nonionic surfactants promote the aggregation of liposomes at a concentration just below the cmc. The efficiency and the minimum concentration able to induce both CF-release and the aggregation of liposomes were closely related with not only the hydrophobicity but also the geometry of the hydrophobic moiety of the surfactant.