Temperature-sensitive releases from liposomes containing hydrophobically modified poly(N-isopropylacrylamide)

被引:26
作者
Kim, JC [1 ]
Kim, MS [1 ]
Kim, JD [1 ]
机构
[1] Korea Adv Inst Sci & Technol, Dept Chem Engn, Yousong Gu, Taejon 305701, South Korea
关键词
liposomes; poly(N-isopropylacrylamide); temperature-sensitivity; dioleoylphosphatidylethanolamine; reverse-phase evaporation vesicles;
D O I
10.1007/BF02699001
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Novel temperature-sensitive liposomes containing hydrophobically modified poly(N-isopropylacrylamide) (HPNIPAM) and their release behaviors were investigated using calcein as a fluorescence probe. Above the lower critical solution temperature (LCST) of the polymer (e.g., 40 degrees C), the degree of calcein release in 280 sec from reverse-phase evaporation vesicles (REVs) of egg phosphatidylcholine (egg PC) was 43 %, while egg PC MLVs was 16 %. Such a large difference of release may be attributed to the lamellarity of liposomes. The incorporation of dioleoylphosphatidylethanolamine (DOPE) into the PC bilayer enhanced the release by 10-13 % at 40 degrees C, probably due to the increased instability of mixture bilayers. Meanwhile, a temperature-sensitive device of DOPE liposomes was prepared by using HPNIPAM as a stabilizer. The optimal ratio of HPNIPAM to lipid to stabilize the bilayer was 0.1. Above the LCST (e.g., 40 degrees C), the release percentage was about 80 % of the entrapped calcein. DOPE liposomes were the most temperature-sensitive among liposomes tested. This is probably because DOPE liposomes disintegrate into a non-liposomal phase, such as hexagonal (H-Pi), by a thermal contraction of HPNIPAM.
引用
收藏
页码:28 / 33
页数:6
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