Pyrene-labeled amphiphilic poly-(N-isopropylacrylamides) prepared by using a lipophilic radical initiator: Synthesis, solution properties in water, and interactions with liposomes

被引:63
作者
Winnik, FM [1 ]
Adronov, A [1 ]
Kitano, H [1 ]
机构
[1] TOYAMA UNIV,DEPT CHEM & BIOCHEM ENGN,TOYAMA 390,JAPAN
来源
CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE | 1995年 / 73卷 / 11期
关键词
liposome; poly-(N-isopropylacrylamide); fluorescence; micelles;
D O I
10.1139/v95-251
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Fluorescently labeled amphiphilic poly-(N-isopropylacrylamides) (PNIPAM) substituted with a N-[4-(1-pyrenyl)butyl]-N-n-octadecyl group at the chain end were prepared by free-radical polymerization in dioxane of N-isopropylacrylamide (NIPAM) using 4,4'-azobis{4-cyano-N,N-[4-(1-pyrenyl)butyl]-n-octadecyl} pentanamide as the initiator. The solution properties of the polymers in water were studied as a function of polymer concentration and temperature. Quasi-elastic light-scattering measurements and fluorescence experiments monitoring the pyrene excimer and pyrene monomer emissions revealed the presence of multimolecular polymeric micelles below the fewer critical solution temperature (LCST) of PNIPAM. These underwent partial, reversible reorganization as they were heated above the LCST. The interactions of the pyrene-labeled amphiphilic PNIPAM with dimyristoylphosphatidylcholine (DMPC) liposomes have been examined in water at 25 degrees C. From fluorescence experiments it was established that the polymeric micelles are disrupted irreversibly upon contact with the liposomes. The anchoring of the polymer chains occurs by insertion of their hydrophobic tail within the phospholipidic bilayer, as evidenced from a large decrease of the pyrene excimer emission relative to pyrene monomer emission. The copolymers remained anchored within the bilayer as the temperature of the copolymer-liposome suspension was raised above the LCST of PNIPAM.
引用
收藏
页码:2030 / 2040
页数:11
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