Effect of polymer architecture on the interactions of hydrophobically-modified poly-(N-isopropylamides) and liposomes

The interactions of hydrophobically-modified poly-(N-isopropylacrylamides) with phospholipid liposomes have been studied as a function of the bilayer phase composition and the polymer architecture, using fluorescence spectroscopy, dynamic light scattering, size exclusion chromatography, and centrifugation assays. Measurements were carried out with polymers carrying hydrophobic groups, either at random along the main chain, or specifically at one chain end. Anchoring of the hydrophobic substituent within the lipid bilayer was ascertained in both systems. Binding constants of the polymer to dimyristoyl phosphatidylcholine (DMPC)/cholesterol, 7/3 molar ratio) liposomes and dipalmitoyl phosphatidylcholine (DPPC)/cholesterol, 7/3 molar ratio) liposomes were evaluated from the centrifugation assays.