Dias Rita S, Innerlohinger Josef, Glatter Otto, Miguel Maria G, Lindman Björn
Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
J Phys Chem B. 2005 May 26;109(20):10458-63. doi: 10.1021/jp0444464.
The compaction and aggregation of DNA induced by cationic surfactants was studied by dynamic light scattering (DLS). Furthermore, the effect on surfactant-compacted DNA of the addition of nonionic amphiphiles and salt was studied. When using sufficiently low amounts of DNA and cetyltrimethylammonium bromide (CTAB), compacted DNA molecules could be monitored by the appearance of a band characterized by lower hydrodynamic radius and by the decrease in the intensity of the peak corresponding to extended DNA molecules. Notably, we observed a region where compacted molecules coexist with extended ones; these two populations were found to be stable with time. For higher concentrations of CTAB, only compacted molecules were observed and the size of the particles increased with time indicating aggregation. The number of globules present in the coexistence region increased linearly with the surfactant concentrations, as given by the area of the band corresponding to this population, which indicates a double-cooperativity of the binding. The DLS experiments were in good agreement with previous fluorescence microscopy studies, with certain advantages over this technique since there is no need to add fluorescence dyes and antioxidants. Furthermore, it allows the study of molecules which are too small to be visualized by fluorescence microscopy.
通过动态光散射（DLS）研究了阳离子表面活性剂诱导的DNA压缩和聚集。此外，还研究了添加非离子两亲物和盐对表面活性剂压缩DNA的影响。当使用足够少量的DNA和十六烷基三甲基溴化铵（CTAB）时，通过出现具有较低流体动力学半径特征的条带以及对应于伸展DNA分子的峰强度的降低，可以监测压缩的DNA分子。值得注意的是，我们观察到一个压缩分子与伸展分子共存的区域；发现这两个群体随时间是稳定的。对于较高浓度的CTAB，仅观察到压缩分子，并且颗粒尺寸随时间增加表明发生了聚集。共存区域中存在的小球数量随表面活性剂浓度线性增加，如对应于该群体的条带面积所示，这表明结合具有双重协同性。DLS实验与先前的荧光显微镜研究结果良好吻合，与该技术相比具有某些优势，因为无需添加荧光染料和抗氧化剂。此外，它允许研究太小而无法通过荧光显微镜观察的分子。
