Rangelov Stanislav, Almgren Mats
Department of Physical Chemistry, University of Uppsala, Box 579, 751 23 Uppsala, Sweden.
J Phys Chem B. 2005 Mar 10;109(9):3921-9. doi: 10.1021/jp0447385.
Copolymers based on poly(ethylene glycol) bearing one or more lipid-mimetic anchors were mixed with glycerylmonooleate (GMO)-a lipid with nonlamellar propensity-to form bulk and particulate bicontinuous cubic phases in water. The particulate phase was obtained via a liquid precursor method. Three forms of copolymer/GMO mixtures were investigated-precursor dispersions in glycerol and bulk and particulate phases in water-by visual observations, dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). The bulk phases were found to very slowly develop a macroscopic appearance that can be associated with the bicontinuous cubic phase. They were prepared in a slight excess of water, which became opalescent in some of the preparations. Cryo-TEM investigation of the excess showed that vesicles and particles with a dense interior coexisted. The precursors were prepared as solutions in glycerol. The viscous liquid material was investigated by DLS. Diffusion coefficients and the corresponding hydrodynamic radii, ranging from about 10 to 30 nm, were calculated. The particles are presumably of a structure similar to that of conventional emulsion droplets with GMO in the interior and copolymer molecules in the outer regions. The particulate phase in water was obtained upon hydration of the liquid precursors. The dispersions were investigated by DLS and cryo-TEM. DLS revealed the formation of nanosized particles. The size was found to increase with increasing copolymer content for copolymers with only one lipid-mimetic anchor, whereas the opposite trend was observed for the formulations with copolymers bearing more than one lipid-mimetic anchor. The shape and interior of the particles were studied by cryo-TEM. It was found that most particles were globular. For some of the compositions, particles with a dense internal structure dominated. The texture of the internal structures was assigned to dispersed bicontinuous cubic or L3 phases. In other compositions, the interior seemingly consists of arrays of interlamellar attachments.
将带有一个或多个类脂模拟锚定基团的聚乙二醇基共聚物与甘油单油酸酯（GMO，一种具有非层状倾向的脂质）混合，以在水中形成本体和颗粒状双连续立方相。颗粒相通过液体前驱体法获得。通过目视观察、动态光散射（DLS）和低温透射电子显微镜（cryo-TEM）研究了三种形式的共聚物/GMO混合物——甘油中的前驱体分散体以及水中的本体相和颗粒相。发现本体相非常缓慢地呈现出一种可与双连续立方相相关联的宏观外观。它们是在略过量的水中制备的，在一些制剂中变成了乳白色。对过量部分的低温透射电子显微镜研究表明，内部致密的囊泡和颗粒共存。前驱体是作为甘油溶液制备的。通过动态光散射研究了粘性液体材料。计算了扩散系数和相应的流体动力学半径，范围约为10至30纳米。这些颗粒可能具有与传统乳液滴类似的结构，内部为GMO，外部区域为共聚物分子。水相中的颗粒相是通过液体前驱体的水合作用获得的。通过动态光散射和低温透射电子显微镜对分散体进行了研究。动态光散射揭示了纳米颗粒的形成。对于仅带有一个类脂模拟锚定基团的共聚物，发现颗粒尺寸随共聚物含量的增加而增大，而对于带有多个类脂模拟锚定基团的共聚物制剂，则观察到相反的趋势。通过低温透射电子显微镜研究了颗粒的形状和内部结构。发现大多数颗粒是球形的。对于某些组合物，具有致密内部结构的颗粒占主导。内部结构的纹理被归因于分散的双连续立方相或L3相。在其他组合物中，内部似乎由层间附着物阵列组成。
