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 spectros copy, dynamic light scattering, size exclusion chromatography, and centrifu gation assays. Measurements were carried out with polymers carrying hydroph obic groups, either at random along the main chain, or specifically at one chain end. Anchoring of the hydrophobic substituent within the lipid bilaye r was ascertained in both systems. Binding constants of the polymer to dimy ristoyl phosphatidylcholine (DMPC)/cholesterol, 7/3 molar ratio) liposomes and dipalmitoyl phosphatidylcholine (DPPC)/cholesterol, 7/3 molar ratio) li posomes were evaluated from the centrifugation assays. (C) 1999 Elsevier Sc ience B.V. All rights reserved.