Zhao Xiaofang, Shang Yazhuo, Liu Honglai, Hu Ying
The State Key Laboratory of Chemical Engineering and Department of Chemistry, East China University of Science and Technology, Shanghai 200237, China.
J Colloid Interface Sci. 2007 Oct 15;314(2):478-83. doi: 10.1016/j.jcis.2007.04.059. Epub 2007 Jul 12.
Interactions between DNA and the cationic gemini surfactant trimethylene-1,3-bis(dodecyldimethylammonium bromide) (12-3-12) in aqueous solution have been investigated by UV-vis transmittance, zeta potential, and fluorescence emission spectrum. Complexes of DNA and gemini surfactant are observed in which the negative charges of DNA are neutralized by cationic surfactants effectively. The DNA-induced micelle-like structure of the surfactant due to the electrostatic and hydrophobic interactions is determined by the fluorescence spectrum of pyrene. It is found that the critical aggregation concentration (CAC) for DNA/12-3-12 complexes depends little on the addition of sodium bromide (NaBr) because of the counterbalance salt effect. However, at high surfactant concentration, NaBr facilitates the formation of larger DNA/surfactant aggregates. Displacement of ethidium bromide (EB) by surfactant evidently illustrates the strong cooperative binding between surfactant and DNA. In contrast to that in the absence of surfactant, the added NaBr at high surfactant concentration influences not only the binding of surfactant with DNA, but also the stability of DNA/EB complex.
通过紫外可见透光率、zeta电位和荧光发射光谱研究了水溶液中DNA与阳离子双子表面活性剂三亚甲基-1,3-双（十二烷基二甲基溴化铵）（12-3-12）之间的相互作用。观察到DNA与双子表面活性剂的复合物，其中DNA的负电荷被阳离子表面活性剂有效中和。芘的荧光光谱确定了由于静电和疏水相互作用导致的表面活性剂的DNA诱导的胶束状结构。发现DNA/12-3-12复合物的临界聚集浓度（CAC）由于抗衡盐效应几乎不受溴化钠（NaBr）添加的影响。然而，在高表面活性剂浓度下，NaBr促进形成更大的DNA/表面活性剂聚集体。表面活性剂对溴化乙锭（EB）的取代明显说明了表面活性剂与DNA之间的强协同结合。与不存在表面活性剂的情况相反，在高表面活性剂浓度下添加的NaBr不仅影响表面活性剂与DNA的结合，还影响DNA/EB复合物的稳定性。
