School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University , Xinxiang, Henan 453007, China.
Langmuir. 2013 Oct 29;29(43):13258-68. doi: 10.1021/la402754y. Epub 2013 Oct 15.
The interaction between biocompatible cholic acid-modified dextrans with different pendent cholic acid groups' content and phosphatidylcholine liposomes was studied by a variety of techniques including isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), turbidity measurements, microscopy imaging (transmission electron microscopy (TEM), and cryo-scanning electron microscopy (cryo-SEM)). The variation of the interaction enthalpy with polymer concentration, as obtained by ITC, highlighted the formation of different aggregates. Complete phase modification, from vesicles covered with a few polymer chains to vesicle disintegration, was observed by turbidity measurements. DSC showed the effect of polymer addition to the liposome gel to liquid-crystalline phase transition, and microscopy images gave information about the size and morphology of the aggregates. The composition, structure, and morphology of polymer/liposome aggregates were found to be strongly influenced by the cholic acid content in the polymer (degree of substitution, DS). Along with a rather monotonous change in the polymer/liposome system's properties with increasing DS, a discontinuity in behavior could also be observed at DS = 4 mol %. For DS ≤ 4 mol %, the polymer/liposome interaction takes place mainly between individual components, and liposome disintegration occurs in a narrow concentration range, whereas for DS > 4 mol % extended physical networks are formed, which last over a wide concentration range. A mechanism of interaction, as a function of DS, is proposed and discussed in detail.
采用多种技术，包括等温滴定微量热法（ITC）、差示扫描量热法（DSC）、浊度测量、显微镜成像（透射电子显微镜（TEM）和冷冻扫描电子显微镜（cryo-SEM）），研究了具有不同侧链胆酸基团含量的生物相容胆酸修饰葡聚糖与磷脂囊泡之间的相互作用。ITC 获得的相互作用焓随聚合物浓度的变化突出了不同聚集体的形成。通过浊度测量观察到从覆盖有少量聚合物链的囊泡到囊泡崩解的完全相转变。DSC 显示了聚合物对脂质体凝胶到液晶相转变的影响，显微镜图像提供了关于聚集体大小和形态的信息。发现聚合物/脂质体聚集体的组成、结构和形态强烈受聚合物中胆酸含量（取代度，DS）的影响。随着聚合物/脂质体系统性能随 DS 的增加而单调变化，在 DS = 4 mol % 处也可以观察到行为的不连续性。对于 DS ≤ 4 mol %，聚合物/脂质体相互作用主要发生在各个组分之间，并且在狭窄的浓度范围内发生脂质体崩解，而对于 DS > 4 mol %，则形成了扩展的物理网络，这些网络在广泛的浓度范围内持续存在。提出并详细讨论了一个随 DS 变化的相互作用机制。
