Barrier properties of lecithin/lysolecithin mixtures.

Light scattering, birefringence and X-ray studies showed that liposomes, with lipid molecules orientated in bilayers, are formed from egg licithin/lysolecithin mixtures up to 50 mol percent of lysolecithin; above this concentration much smaller mixed micelles are formed. Permeability studies demonstrated a dramatic increase in the permeability of the liposomes when the lyso concentration exceeds 22.5 mol percent. X-ray studies indicated a significant decrease in bilayer thickness with increasing lysolecithin concentration. It is suggested that decreased interaction energy between the lipid molecules in the bilayer is responsible for the inability of the thin bilayers to act as an effective permeability barrier.