Small-angle x-ray scattering study of the interaction of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers with lipid bilayers
Small-angle x-ray scattering study of the interaction of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers with lipid bilayers
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DOI：
10.1021/bm034134r
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发表时间：
2003-11-01
影响因子：
6.2
通讯作者：
Seifert, S
中科院分区：
文献类型：
--
作者：
Firestone, MA;Wolf, AC;Seifert, S
使用小角 X 射线散射 (SAXS) 和热分析（差示扫描量热法，DSC）研究了一系列聚（环氧乙烷）-b-聚（环氧丙烷）-b-聚（环氧乙烷）（PEO-PPO-PEO）三嵌段共聚物的分子结构和与脂质双层相互作用的性质之间的关系。已发现疏水性聚环氧丙烷（PPO）嵌段中分子重复单元的数量是三嵌段共聚物-脂质双层缔合性质的关键决定因素。对于基于二肉豆蔻酰-sn-甘油-3-磷酸胆碱（DMPC）的生物膜结构，具有与脂质双层的酰基链尺寸相称的PPO链长度的聚合物产生与良好整合（进入脂质双层）PPO块一致的高度有序、膨胀的层状结构。较短 PPO 链长的三嵌段共聚物产生的材料的结构特征类似于 DMPC 在水中的简单分散体。增加良好整合的三嵌段共聚物的浓度（从 4 mol% 到 12 mol%）可增强层状相的结构有序性，而浓度超过 16 mol% 会导致六方相的形成。对温度引起的这些中间相（复杂流体）结构变化的检查表明，如果温度充分降低，所有组合物都排除聚合物，从而表现出水合 DMPC 双层的特征 SAXS 模式。升高温度促进具有足以插入膜的PPO链长的聚合物更好地插入。在用PEO-PPO-PEO聚合物制备的组合物中没有观察到温度诱导的结构变化，其特征是PPO长度不足以允许完全掺入脂质双层中。
The relationship between molecular architecture and the nature of interactions with lipid bilayers has been studied for a series of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers using small-angle X-ray scattering (SAXS) and thermal analysis (differential scanning calorimetry, DSC). The number of molecular repeat units in the hydrophobic poly(propylene oxide), PPO, block has been found to be a critical determinant of the nature of triblock copolymer-lipid bilayer association. For dimyristoyl-sn-glycero-3-phosphocholine (DMPC)-based biomembrane structures, polymers possessing a PPO chain length commensurate with the acyl chain dimensions of the lipid bilayer yield highly ordered, swollen lamellar structures consistent with well-integrated (into the lipid bilayer) PPO blocks. Triblock copolymers of lesser PPO chain length yield materials with structural characteristics similar to a simple dispersion of DMPC in water. Increasing the concentration (from 4 to 12 mol %) of well-integrated triblock copolymers enhances the structural ordering of the lamellar phase, while concentrations exceeding 16 mol % result in the formation of a hexagonal phase. Examination of temperature-induced changes in the structure of these mesophases (complex fluids) reveals that if the temperature is reduced sufficiently, all compositions exclude polymer and thus exhibit the characteristic SAXS pattern for hydrated DMPC bilayers. Increasing the temperature promotes better insertion of the polymers possessing PPO chain lengths sufficient for membrane insertion. No temperature-induced structural changes are observed in compositions prepared with PEO-PPO-PEO polymers that feature PPO length insufficient to permit full incorporation into the lipid bilayer.