Qu Xiaozhong, Omar Leila, Le Thi Bich Hang, Tetley Laurence, Bolton Katherine, Chooi Kar Wai, Wang Wei, Uchegbu Ijeoma F
School of Pharmacy, University of London, 29-39 Brunswick Square, London, UK.
Langmuir. 2008 Sep 16;24(18):9997-10004. doi: 10.1021/la8007848. Epub 2008 Aug 9.
Self-assembly is fundamental to the biological function of cells and the fabrication of nanomaterials. However, the origin of the shape of various self-assemblies, such as the shape of cells, is not altogether clear. Polymeric, oligomeric, or low molecular weight amphiphiles are a rich source of nanomaterials, and controlling their self-assembly is the route to tailored nanosystems with specific functionalities. Here, we provide direct evidence that a particular molecular architecture, polymeric branching, leads to a rare form of self-assembly, the planar nanodisc. Cholesterol containing self-assemblies formed from amphiphilic linear or branched cetyl poly(ethylenimine) (Mn approximately 1000 Da) or amphiphilic cetyl poly(propylenimine) dendrimer derivatives (Mn approximately 2000 Da) show that branching, by reducing the hydrophilic headgroup area, alters the shape of the self-assemblies transforming closed 60 nm spherical bilayer vesicles to rare 50 nm x 10 nm planar bilayer discs. Increasing the hydrophilic headgroup area, by the inclusion of methoxy poly(ethylene glycol) moieties into the amphiphilic headgroup, transforms the planar discs to 100 nm spherical bilayer vesicles. This study provides insight into the key role played by molecular shape on molecular self-organization into rare nanodiscs.
自组装是细胞生物学功能和纳米材料制备的基础。然而，各种自组装体的形状起源，如细胞的形状，尚不完全清楚。聚合物、低聚物或低分子量两亲物是丰富的纳米材料来源，控制它们的自组装是制备具有特定功能的定制纳米系统的途径。在这里，我们提供了直接证据，表明一种特定的分子结构——聚合物支化，会导致一种罕见的自组装形式，即平面纳米盘。由两亲性线性或支化十六烷基聚（乙烯亚胺）（Mn约1000 Da）或两亲性十六烷基聚（丙烯亚胺）树枝状大分子衍生物（Mn约2000 Da）形成的含胆固醇自组装体表明，支化通过减小亲水头基面积，改变了自组装体的形状，将封闭的60 nm球形双层囊泡转变为罕见的50 nm×10 nm平面双层盘。通过在两亲性头基中引入甲氧基聚（乙二醇）部分来增加亲水头基面积，可将平面盘转变为100 nm球形双层囊泡。这项研究深入了解了分子形状在分子自组装成罕见纳米盘中所起的关键作用。
