ELECTRON-MICROSCOPIC DEMONSTRATION OF THE PENETRATION OF LIPOSOMES THROUGH SKIN

To verify the penetration of liposomes through skin, we have used lipo somes with encapsulated protein G-gold conjugate in a gel vehicle. Ski n samples were examined 2, 4, 24, 48, and 72 h after liposome applicat ion. Our findings show that the penetration of liposomes through skin depends mainly on their size. Liposomes up to 600 nm in diameter penet rate through skin rather easily, whereas liposomes 1000 nm and more in diameter remain interiorized in the stratum corneum. The main penetra tion of liposomes proceeds along the hair sheaths as indicated by larg er amounts of free liposomes in the cerium of guinea pigs.