Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
Biomacromolecules. 2010 Dec 13;11(12):3571-7. doi: 10.1021/bm101033g. Epub 2010 Nov 10.
A prerequisite for the use of dendrimers as drug delivery vehicles is the detailed molecular understanding of the drug interaction. The purpose of this study was to characterize the self-assembly process between siRNA and generation 7 poly(amidoamine) dendrimers and the resulting dendriplexes in aqueous solution using structural and calorimetric methods combined with molecular dynamics simulations. Complexes with a length scale of 150 nm showed a decreasing size with increasing amine-to-phosphate ratio by dynamic light scattering. At the molecular level, individual dendrimers studied by small-angle X-ray scattering (SAXS) showed no change in size upon siRNA binding, suggesting a rigid sphere behavior. Isothermal titration calorimetry (ITC) demonstrated exothermic binding with a concentration-dependent collapse of complexes. Both the experimentally determined ΔH(bind) and size were in close accordance with molecular dynamics simulations. This study demonstrates the unique complementarity of SAXS, ITC, and modeling for the detailed description of the molecular interactions between dendrimers and siRNA during dendriplex formation.
作为药物传递载体使用树枝状大分子的一个前提条件是对药物相互作用的详细分子理解。本研究的目的是使用结构和量热法结合分子动力学模拟来表征 siRNA 和第 7 代聚（酰胺-胺）树枝状大分子之间在水溶液中的自组装过程以及由此产生的树枝状聚合物。通过动态光散射，具有 150nm 长度尺度的复合物显示出随着胺-磷酸比值的增加而减小的尺寸。在分子水平上，通过小角 X 射线散射（SAXS）研究的单个树枝状大分子在与 siRNA 结合时没有大小变化，表明其具有刚性球体行为。等温滴定量热法（ITC）表明，结合是放热的，复合物的浓度依赖性坍塌。实验测定的 ΔH(bind)和大小与分子动力学模拟非常吻合。这项研究证明了 SAXS、ITC 和建模在详细描述树枝状聚合物和 siRNA 之间在树枝状聚合物形成过程中的分子相互作用方面的独特互补性。
