Dynamics of lipid flip-flop within liposomes and their modulation by polyacrylamide polymers.

摘要

Chapter I describes the effects of morphological changes in the hydrophobically modified PNIPAM polymers (1-6) on the inter- and intraliposomal ("flip-flop") dynamics of lipids, with the polymers as extrinsic modulators in surface differentiated liposomes of 7-F/7-NF.;All the polymers showed negligible effects on the flip-flop rate at 25;The interliposomal transfer of polymers was tested by mixing "donor" liposomes made up of 7-NF, loaded with polymers 2 or 3, and "acceptor" liposomes composed of surface differentiated liposomal 7-F/7-NF. Both polymers, 2 and 3, displayed similar interliposomal transfer profiles, i.e., no transfer of either polymer at 35;Chapter II describes methodology for the comparative dynamic analysis of thermally-driven flip and flop in liposomes. The flip and flop of probe lipid NBD-PE (11) were measured by incubating "inside-only" and "outside-only" labeled liposomes, respectively. The extent of "flipped" (exo) and "flopped" (endo) 11 was seen to increase with both the temperature and duration of incubation, with an obvious "jump" in the rate above the T