包覆NIPAM—ODA双亲共聚物的脂质体的温控释放行为

为了研究对温度敏感的双亲性共聚物包覆的脂质体的温控释放行为,合成了Ｎ－异丙基丙烯酰胺（ＮＩＰＡＭ）和丙烯酸十八酯（ＯＤＡ）的共聚物。利用荧光探针法研究了共聚物水溶液随温度升高时出现的ＬＣＳＴ现象,表明该高分子在温度升高到３０℃以上时存在着明显的相分离行为。

TEMPERATURECONTROLLED RELEASE OF AN AQUEOUS MARKER FROM LIPOSOMES COATED WITHNIPAMODA COPOLYMERS

To study the temperaturecontrolled release behavior of the liposome coated with an amphiphilic copolymer which is temperaturesensitive, the copolymer of Nisopropylacrylamide (NIPAM) and octadecyl acrylate (ODA) was synthesized. The phenomenon of LCST(Lower Critical Solution Temperature)of the copolymer in aqueous solution with the increase of the temperature was studied by using fluorescence probe method. Results showed that the obvious phase separation occurs when temperature was increased to 30 . The release property of small unilamellar vesicles (SUV) coated with the copolymer was studied by using 5(6)carboxyfluorescein (5(6)CF) as a water soluble marker. Results showed that the coating of the copolymer on the liposomal surface resulted in reduction of the release below 30 and enhancement of the release above 30 . It indicated that the temperaturecontrolled release behavior of the liposome was directly related to the phase separation behavior of the coating copolymer when temperature was increased to its LSCT. Moreover, fluorescence polarization method was used to study the influence of the coating copolymer on the fluidity of the liposomal membrane. Results showed that at temperature below 30 the fluidity of the liposomal membrane increased with the increase of temperature; however, at temperature above 30 the fluidity of the liposomal membrane decreased with the increase of temperature. It further indicated that the copolymer which was bound at the surface of the liposome can destroy the liposomal membrane when temperature was increased at or above its LCST.