Selective permeabilization of lipid membranes by photodynamic action via formation of hydrophobic defects or pre-pores

► Photosensitization induces lipid flip-flop and carboxyfluorescein leakage in unsaturated liposomes via singlet oxygen attack. ► Photodynamic treatment does not stimulate potassium chloride efflux from liposomes. ► Photodynamically induced membrane permeability depends on lipophilicity of permeating compounds. ► Oxidative permeabilization of membranes involves formation of hydrophobic pores.