Interaction between a novel amphiphilic polymer and liposomes

We synthesized a novel amphiphilic polymer consisting of octadecylacrylamid e and N,N-dimethylacrylamide with a molar ratio of 99:1. The polymer-induce d aggregation of liposomes in an adequate lipid:polymer ratio. However, cal cein, a water-soluble fluorescent dye entrapped in the large unilamellar li posomes (LUVs) did not leak out significantly although hydrophobic residues of the polymer penetrated into the lipid bilayer. Liposome aggregates by t he polymer could be easily collected by low-speed centrifugation for 10 min at 1400 x g and no significant leakage of the entrapped calcein inside the liposomes was observed. Dynamic light scattering (DLS) measurements showed that liposomes were enlarged in apparent particle size being coated with t he polymer or aggregated by cross-linking. The polymer-coated liposomes wer e more stable against the detergent than the liposomes without a polymer co ating. (C) 1998 Elsevier Science Limited. All rights reserved.