Mobility of Poly(Ethylene Oxide) Segments on Surface of Lecithin Liposomes

Abstract

To better understand the dynamics of PEO-lipid-modified phosphatidylcholine liposomes ("fusogenic liposomes"), the mobility of the PEO segment on the liposomal surface and the fluidity of the bilayer were investigated by measuring the spin-lattice relaxation time (T 1 ) by 13 C-NMR spectroscopy and by fluorescence depolarization. 13 C-NMR studies revealed that the PEO-lipids in this work exhibit similar behavior on liposomal surfaces irrespective of the PEO chain length. Furthermore, with regard to the relationship between morphology and dynamics of the PEO-lipid and phosphatidylcholine mixture, it was found that the mobility of PEO segments are altered by the morphology; liposome < aqueous micelle < monomeric dispersion in organic solution. Fluorescence depolarization studies revealed that liposomal membranes were tighter with the addition of PEO-lipid(12,a31) than with the addition of a13). In contrast, the reconstitution of PEO-lipid(12,a5) into liposomes increased membrane fluidity.

Preparation of Amino Acid Conjugated Nano-Magnetic Particles for Delivery Systems

“…Especially, the efficient introduction of target molecules into the cell using nanomaterials [4][5][6][7] is significant in medical field to realize the nondisruptive analysis and safety treatment for the disease [8].…”