物理化学学报2011，Vol.27Issue(9)：2217-2221,5.
表面活性素单分子膜在空气/水界面的迟滞现象
Hysteresis Behavior of Surfactin Monolayer at the Air/Water Interface
摘要
Abstract
Surfactin,one of the most surface-active microbial lipopeptides,can readily form an insoluble monolayer at the air/water interface.Consecutive compression-expansion cycles of surfactin with a β-hydroxyl fatty acid chain consisting of 14 carbon atoms were studied by a Langmuir film balance.A larger hysteresis loop was observed when the compression isotherm reached a plateau compared with that expanded at a lower surface pressure (20 mN· m-1).The 2nd cycle was shifted towards smaller molecular areas compared with the 1st cycle.We also studied the hysteresis cycles of the surfactin monolayer on subphase of different pH values.With a decrease in the subphase pH the hysteresis loop became smaller and the expansion isotherm curve underwent a longer pseudo plateau.Furthermore,the morphologies of the surfactin monolayers in the plateau region,which were transferred onto a mica surface,were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM).Both AFM and SEM images gave three-dimensional surface aggregates with heights ranging from tens to hundreds of nanometers.The above results suggest that the formation of three-dimensional surface aggregates at the plateau region induces a large hysteresis loop in the surfactin monolayer,which can also be attributed to the submergence of molecules into the subphase when the peptide loop in the surfactin molecule is ionized.关键词
压缩-扩张循环/迟滞环/原子力显微镜/扫描电子显微镜/表面聚集体Key words
Compression-expansion cycle/Hysteresis loop/AFM/SEM/Surface aggregate分类
化学化工引用本文复制引用
杨莹,宋昌盛,叶汝强,牟伯中..表面活性素单分子膜在空气/水界面的迟滞现象[J].物理化学学报,2011,27(9):2217-2221,5.基金项目
国家高技术研究发展计划项目(863) (2009AA063503)资助The project was supported by the National High Technology Research and Development Program of China (863) (2009AA063503). （863）
