Preparation and properties of aqueous dispersions of phosphatidylcholine-cholesteryl ester or ether mixtures

The injection of a mixture of 2-oleoyl-1-paimitoyl-sn-glycero-3-phosphatidy lcholine and cholesterol ester or ether (cholesteryl oleate, 3 beta-(9,10-c is-octadecenoxy)-5-cholestene. or 3 beta-[9-(7-nitrophenyl-2-oxa-1,3-diazol -4-yl)aminononyloxy]-5-cholestene at a molar ratio of 3 : 1 in isopropanol) into a 100-fold excess of an aqueous buffer gives dispersions stable in aq ueous media at concentrations of the cholesterol derivative below 10(-4) M. The dispersions an highly homogeneous, and, according to the data of elect ion microscopy and granulometry, particles with a mean diameter of 100-140 nm have a typical regular structure. Cholesteryl oleate of the dispersions is efficiently internalized by the Hep G2 hepatoma cells. The dispersions c an be used in biochemical and microscopic studies of intracellular metaboli sm and transport of nonpolar lipids in living cultured cells.