PERMEATION OF SUPEROXIDE ANION THROUGH THE BILAYER OF VESICLES OF A SYNTHETIC AMPHIPHILE

Large unilamellar vesicles, prepared with dioctadecyldimethylammonium chloride, entrap nitroblue tetrazolium. Addition of solid KO2, or prod uction of superoxide anion by riboflavin photolysis, to nitroblue tetr azolium-containing dioctadecyldimethylammonium vesicles results in the formation of monoformazan above the phase-transition temperature of t he bilayer. Below the phase-transition temperature the yield of monofo rmazan is negligible. These results demonstrate that superoxide anion permeates vesicles above the phase-transition temperature of the bilay er.