Bayati Solmaz, Galantini Luciano, Knudsen Kenneth D, Schillén Karin
Division of Physical Chemistry, Department of Chemistry, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
Department of Chemistry, Sapienza University of Rome , P. le A. Moro 5, 00185 Rome, Italy.
Langmuir. 2015 Dec 22;31(50):13519-27. doi: 10.1021/acs.langmuir.5b03828. Epub 2015 Dec 8.
A comprehensive experimental study on the interaction between the PEO-PPO-PEO block copolymer P123 (EO20PO68EO20) and the anionic bile salt sodium glycodeoxycholate (NaGDC) in water has been performed. The work was aimed at investigating the suitability of using P123 as bile salt sequestrant beside the fundamental aspects of PEO-PPO-PEO block copolymer-bile salt interactions. Various experimental techniques including dynamic and static light scattering, small-angle X-ray scattering, and differential scanning calorimetry (DSC) were employed in combination with electrophoretic mobility measurements. The system was investigated at a constant P123 concentration of 1.74 mM and with varying bile salt concentrations up to approximately 250 mM NaGDC (or a molar ratio n(NaGDC)/n(P123) = 144). In the mixed P123-NaGDC solutions, the endothermic process related to the self-assembly of P123 was observed to gradually decrease in enthalpy and shift to higher temperatures upon progressive addition of NaGDC. To explain this effect, the formation of NaGDC micelles carrying partly dehydrated P123 unimers was proposed and translated into a stoichiometric model, which was able to fit the experimental DSC data. In the mixtures at low molar ratios, NaGDC monomers associated with the P123 micelle forming a charged "P123 micelle-NaGDC" complex with a dehydrated PPO core. These complexes disintegrated upon increasing NaGDC concentration to form small "NaGDC-P123" complexes visualized as bile salt micelles including one or a few P123 copolymer chains.
针对聚环氧乙烷-聚环氧丙烷-聚环氧乙烷嵌段共聚物P123（EO20PO68EO20）与阴离子胆盐甘氨脱氧胆酸钠（NaGDC）在水中的相互作用，开展了一项全面的实验研究。这项工作旨在研究将P123用作胆盐螯合剂的适用性，以及聚环氧乙烷-聚环氧丙烷-聚环氧乙烷嵌段共聚物与胆盐相互作用的基本方面。结合电泳迁移率测量，采用了多种实验技术，包括动态和静态光散射、小角X射线散射以及差示扫描量热法（DSC）。该体系在P123浓度恒定为1.74 mM的条件下进行研究，胆盐浓度变化范围高达约250 mM NaGDC（或摩尔比n(NaGDC)/n(P123)=144）。在P123-NaGDC混合溶液中，观察到与P123自组装相关的吸热过程在逐渐加入NaGDC后，焓值逐渐降低且向更高温度移动。为了解释这种效应，提出了携带部分脱水P123单聚体的NaGDC胶束的形成，并将其转化为一个化学计量模型，该模型能够拟合实验DSC数据。在低摩尔比的混合物中，NaGDC单体与P123胶束结合，形成带有脱水PPO核的带电“P123胶束-NaGDC”复合物。随着NaGDC浓度增加，这些复合物分解，形成小的“NaGDC-P123”复合物，可视作包含一条或几条P123共聚物链的胆盐胶束。
