Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
Langmuir. 2013 Aug 27;29(34):10648-57. doi: 10.1021/la400683u. Epub 2013 Aug 13.
The interactions between the lipopeptide Surfactin and four betaines, N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SDDAB), N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (STDAB), N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SHDAB), and N-dodecyl-N,N-dimethyl-2-ammonio-acetate (C12BE) are studied by surface tension and small-angle neutron scattering (SANS). SDDAB, STDAB, and SHDAB have the same headgroup but different hydrophobic chains. C12BE has different headgroup but the same hydrophobic chain with SDDAB. According to the interfacial parameters calculated from surface tension, the synergism between Surfactin and betaine is relevant with the molecule structure of betaine and the mole ratio of them. For betaines, the optimum alkyl chain length (STDAB) and long enough separation between positive charge and negative charge in headgroup are responsible for highest synergetic interaction with Surfactin. The aggregates of individual Surfactin and the mixtures of Surfactin and sulfopropyl betaines are predicted to be spherical based on the packing parameter (pp) and the average packing parameter (P(av)), which is in close qualitative agreement with SANS data analysis, while Surfactin/C12BE forms ellipsoidal micelles due to the smaller headgroup of C12BE.
脂肽表面活性剂与四种甜菜碱（十二烷基-N,N-二甲基-3-氨丙基磺酸盐（SDDAB）、十四烷基-N,N-二甲基-3-氨丙基磺酸盐（STDAB）、十六烷基-N,N-二甲基-3-氨丙基磺酸盐（SHDAB）和十二烷基-N,N-二甲基-2-氨乙酸盐（C12BE））的相互作用通过表面张力和小角中子散射（SANS）进行研究。SDDAB、STDAB 和 SHDAB 具有相同的头基但不同的疏水链。C12BE 具有不同的头基但与 SDDAB 具有相同的疏水链。根据表面张力计算得到的界面参数，表面活性剂与甜菜碱的协同作用与甜菜碱的分子结构和它们的摩尔比有关。对于甜菜碱，最佳的烷基链长度（STDAB）和头基中正电荷与负电荷之间足够长的距离是与表面活性剂协同作用的最高因素。根据堆积参数（pp）和平均堆积参数（P(av)），预测单个表面活性剂的聚集体和表面活性剂与磺基甜菜碱的混合物为球形，这与 SANS 数据分析非常吻合，而由于 C12BE 的头基较小，表面活性剂/C12BE 形成椭圆形胶束。
