Caracciolo Giulio, Pozzi Daniela, Caminiti Ruggero, Amenitsch Heinz
Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185 Rome, Italy.
J Phys Chem B. 2006 Oct 26;110(42):20829-35. doi: 10.1021/jp0620926.
The mechanism of formation of multicomponent lipoplexes was investigated by means of synchrotron Small-Angle X-ray Diffraction (SAXD). Mixed lipid dispersions were prepared by mixing different populations of binary cationic liposomes. When adding DNA to mixed lipid dispersions, multicomponent lipoplexes spontaneously formed exhibiting structural properties, i.e., membrane thickness, surface charge density, and one-dimensional DNA packing density, intermediate between those of binary lipoplexes. These results suggested that DNA lets liposomes come into contact and fuse and that a complete lipid mixing at the molecular level occurs. The equilibrium structure of multicomponent lipoplexes was found to be unique and did not depend on the number and kind of populations composing lipid dispersion but only on the lipid species involved and on their relative molar ratio. According to recent theoretical models we identified two-dimensional lipid mixing entropy as the key factor regulating the existence of only multicomponent lipoplexes with ideally mixed lipid species.
通过同步加速器小角X射线衍射（SAXD）研究了多组分脂质体复合物的形成机制。通过混合不同群体的二元阳离子脂质体制备混合脂质分散体。当向混合脂质分散体中加入DNA时，多组分脂质体复合物自发形成，其表现出的结构性质，即膜厚度、表面电荷密度和一维DNA堆积密度，介于二元脂质体复合物之间。这些结果表明DNA使脂质体相互接触并融合，且在分子水平上发生了完全的脂质混合。发现多组分脂质体复合物的平衡结构是独特的，并且不取决于构成脂质分散体的群体数量和种类，而仅取决于所涉及的脂质种类及其相对摩尔比。根据最近的理论模型，我们确定二维脂质混合熵是调节仅具有理想混合脂质种类的多组分脂质体复合物存在的关键因素。
