分子动力学模拟研究荧光分子芘在磺基甜菜碱胶束中的增溶

Molecular dynamics simulation of pyrene solubilization in a sulfobetaine micelle

采用分子动力学模拟研究了荧光分子芘在磺基甜菜碱两性表面活性剂聚集体中的增溶现象.结果表明,芘分子自发地自溶液中增溶进入胶束疏水内核的栅栏层区域.当胶束溶液中芘分子的局部浓度增大时,两个芘分子可以同时增溶进胶束的栅栏层区域,此时两个芘分子形成-共轭堆积的激发态络合物.但是由于荧光分子之间的弱-相互作用,激发态络合物在胶束中是不稳定的,表现为两个芘分子的多次结合和分离.模拟表明,分子动力学方法可以在分子水平上研究荧光探针分子在表面活性剂胶束中的增溶位点,解释荧光分子在胶束中的动力学现象.

The structural and dynamical properties of the solubilization process of pyrene within a zwitterionic surfactant sulfohetaine micelle were studied using molecular dynamics simulations. Our results showed that free pyrene as the fluorescence probe can be solubilized spontaneously into the micelle and prefers to be located in the hydrophobic core region. When the local concentration of pyrene increased, two probes could both enter into the core region and the excited dimmer of pyrene was formed, which presented a stacking mode of π-π conjugation. Since the n-n stacking interaction was very week, the formation of the excimer was a dynamic process with the two pyrene molecules alternately separating and associating with each other. The simulation showed that the method of molecular dynamics can investigate the location of probe molecules in the micelle in the molecular level, and interpret the dynamic behavior of the probes.