Temperature sensitization of liposomes by use of N-isopropylacrylamide copolymers with varying transition endotherms.
Temperature sensitization of liposomes by use of N-isopropylacrylamide copolymers with varying transition endotherms.
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DOI：
10.1021/bc034205j
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发表时间：
2004-08
影响因子：
4.7
通讯作者：
Keisuke Yoshino;A. Kadowaki;T. Takagishi;K. Kono
中科院分区：
文献类型：
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作者：
Keisuke Yoshino;A. Kadowaki;T. Takagishi;K. Kono
以N-丙烯酰基吡咯烷（APr）、N，N-二甲基丙烯酰胺（DMAM）和N-异丙基甲基丙烯酰胺（NIPMAM）为共聚单体，合成了3种具有相同构象转变温度和不同构象转变吸热的N-异丙基丙烯酰胺（NIPAM）共聚物。将两个十二烷基基团并入这些共聚物的末端作为用于固定到脂质体膜的锚。制备了含这些共聚物的蛋黄磷脂酰胆碱脂质体，并研究了其温敏性、释放和包结性质。而这些共聚物在约100 ℃时表现出构象转变。在40 ° C下，转变的Δ H以聚（APr-共-NIPAM）<聚（DMAM-co-NIPAM）<聚（NIPMAM-co-NIPAM）的顺序增加。含有聚（NIPMAM-co-NIPAM）的脂质体显示出在转变温度以上包封的钙黄绿素的急剧释放增强，而含有聚（DMAM-co-NIPAM）的脂质体和含有聚（APr-co-NIPAM）的脂质体分别在该温度以上表现出钙黄绿素释放的中度和轻微增强。相反，含有聚（APr-co-NIPAM）的脂质体在转变温度以上显示出显著的聚集，但是对于具有聚（NIPMAM-co-NIPAM）的脂质体几乎没有观察到聚集，表明聚（APr-co-NIPAM）更有效地使脂质体表面疏水。因此，我们得出结论，具有大Δ H的共聚物适合于获得具有温度敏感内容物释放性质的功能性脂质体，而具有小Δ H的共聚物适合于制备具有温度敏感表面性质的功能性脂质体。
Three kinds of copolymers of N-isopropylacrylamide (NIPAM) with the same conformational transition temperature and varying transition endotherms were synthesized with N-acryloylpyrrolidine (APr), N,N-dimethylacrylamide (DMAM), and N-isopropylmethacrylamide (NIPMAM) as the comonomers. Two dodecyl groups were incorporated into the termini of these copolymers as an anchor for the fixation to a liposomal membrane. Egg yolk phosphatidylcholine liposomes having these copolymers were prepared and their temperature-sensitive contents release and association properties were investigated. While these copolymer exhibited a conformational transition at ca. 40 degrees C, DeltaH for the transition increased in the order of poly(APr-co-NIPAM) < poly(DMAM-co-NIPAM) < poly(NIPMAM-co-NIPAM). The liposomes containing poly(NIPMAM-co-NIPAM) showed a drastic release enhancement of entrapped calcein above the transition temperature, whereas the liposomes with poly(DMAM-co-NIPAM) and those with poly(APr-co-NIPAM) exhibited moderate and slight enhancement of calcein release above that temperature, respectively. On the contrary, the liposomes containing poly(APr-co-NIPAM) showed significant aggregation above the transition temperature, but the aggregation was hardly observed for the liposomes having poly(NIPMAM-co-NIPAM), indicating that poly(APr-co-NIPAM) more efficiently made the liposome surface hydrophobic. Thus, we concluded that the copolymer with a large DeltaH is suitable for obtaining functional liposomes with a temperature-sensitive contents release property, whereas the copolymer with a small DeltaH is appropriate for preparing functional liposomes with a temperature-sensitive surface property.