Xu Hai, Wang Jing, Han Shuyi, Wang Jiqian, Yu Daoyong, Zhang Hongyu, Xia Daohong, Zhao Xiubo, Waigh Thomas A, Lu Jian R
Centre for Bioengineering and Biotechnology and School of Chemistry and Chemical Engineering, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao 266555, China.
Langmuir. 2009 Apr 7;25(7):4115-23. doi: 10.1021/la802499n.
Peptide amphiphiles readily self-assemble into a variety of nanostructures, but how molecular architectures affect the size and shape of the nanoaggregates formed is not well understood. From a combined TEM and AFM study of a series of cationic peptide surfactants AmK (m = 3, 6, and 9), we show that structural transitions (sheets, fibers/ worm-like micelles, and short rods) can be induced by increasing the length of the hydrophobic peptide region. The trend can be interpreted using the molecular packing theory developed to describe surfactant structural transitions, but the entropic gain, decreased CAC, and increased electrostatic interaction associated with increasing the peptide hydrophobic chain need to be taken into account appropriately. Our analysis indicates that the trend in structural transitions observed from AmK peptide surfactants is opposite to that obtained from conventional monovalent ionic surfactants. The outcome reflects the dominant role of hydrophobic interaction between the side chains opposed by backbone hydrogen bonding and electrostatic repulsion between lysine side chains.
肽两亲分子很容易自组装成各种纳米结构，但分子结构如何影响所形成的纳米聚集体的大小和形状尚不清楚。通过对一系列阳离子肽表面活性剂AmK（m = 3、6和9）进行透射电子显微镜（TEM）和原子力显微镜（AFM）联合研究，我们发现增加疏水肽区域的长度可以诱导结构转变（片层、纤维/蠕虫状胶束和短棒）。这种趋势可以用为描述表面活性剂结构转变而发展的分子堆积理论来解释，但需要适当考虑与增加肽疏水链相关的熵增、临界聚集浓度（CAC）降低和静电相互作用增强。我们的分析表明，从AmK肽表面活性剂观察到的结构转变趋势与从传统单价离子表面活性剂获得的趋势相反。这一结果反映了主链氢键对面的侧链之间疏水相互作用以及赖氨酸侧链之间静电排斥的主导作用。
