C_（12）C_6C_（12）Br_2/C_（12）E_（10）混合表面活性剂与DNA之间的相互作用

摘要

本文以构建有效的非病毒基因载体为目的,研究了C12C6C12Br2/C12E10混合表面活性剂组成对其与DNA之间相互作用的影响,并对混合表面活性剂与DNA形成的聚集体结构和形貌进行了表征。结果表明,当固定混合表面活性剂的总浓度为1.0 mmol/L时,混合表面活性剂组成的改变会引起混合体系浊度、聚集体表面电荷和聚集体形貌发生变化。当C12E10的摩尔分数（X（C12E10））较低时,混合表面活性剂以带有正电荷并具有两条疏水链的C12C6C12Br2为主,其与DNA分子能发生很强的静电吸引作用和疏水相互作用,使DNA分子发生凝聚;随着X（C12E10）的提高,混合表面活性剂中C12C6C12Br2减少,导致混合表面活性剂与DNA之间的静电吸引作用和疏水相互作用减弱,并由于C12E10头基上EO链的空间位阻作用,使得DNA分子的＂球状＂凝聚体松散成为较大的＂类网状＂聚集体,最后呈＂无规则自由卷曲＂状态。%To develop an effective non-viral gene delivery system,the interaction between the mixed cationiconionic surfactant system（C12C6C12Br2/C12E10） and DNA was studied.The effect of the composition of mixed surfactants on the interaction of C12C6C12Br2/C12E10 with DNA was investigated,and the structure and morphology of complex formed by the mixed surfactants and DNA were characterized.The results showed that the properties of C12C6C12Br2/C12E10-DNA complexes including turbidity,surface charge,and morphologies depend on the molar fraction of C12E10（X（C12E10））.At lower X（C12E10）,the cationic Gemini surfactant C12C6C12Br2 with bi-charged hydrophilic headgroups and twin hydrophobic chains is the dominant.C12C6C12Br2 can strongly interact with DNA by both electrostatic and hydrophobic interactions,thus the DNA molecules are condensed to ＂globule＂ structures.As increasing of the X（C12E10）,the ratio of C12C6C12Br2 in the mixed surfactant composition is reduced so that the electrostatic and hydrophobic interactions between mixed surfactants and DNA is weakened,meanwhile,the increase of C12E10 in the mixed surfactant composition enhance the steric hindrance between the headgroups of C12E10.Under the co-interaction of these two factors the structure of C12C6C12Br2/C12E10-DNA complex is changed from compact ＂globule＂ to incompact ＂network＂,and finally to ＂wormlike random coil＂.