同步辐射X射线衍射研究短链DNA/磷脂多层膜的结构  

Structure of solid-supported short chain DNA/lipid multilayers

作　　者：陆颖[1] 胡书新[1] 麦振洪[1] 李明[1] 

机构地区：[1]中国科学院物理研究所,北京100190

出　　处：《核技术》2009年第12期897-900,共4页Nuclear Techniques

摘　　要：应用同步辐射低角X射线衍射研究由短链DNA/磷脂在固体表面形成的复合多层膜结构。将DNA/磷脂混合溶液(DOTAP/DOPC混合磷脂,其中ΦDOTAP定义为DOTAP在混合磷脂中的质量百分比)浇铸在经过亲水处理的表面上,在溶剂蒸发过程中自组装形成高度有序的多层膜结构。按DNA骨架上所带负电荷的数目与DOTAP所带正电荷数目相等的比例制备一系列具有不同ΦDOTAP值的样品。实验结果表明,随着DNA含量的增加,多层膜先后出现DNA贫瘠相和DNA富集相。在DNA贫瘠相中,DNA分子被包埋在磷脂分子的亲水头中;而在DNA富集相中,DNA分子紧密排列在磷脂的亲水头层间。并且详细分析了DNA/磷脂多层膜出现DNA贫瘠相和DNA富集相以及产生相变的原因。Synchrotron radiation X-ray diffraction study was performed on short chain DNA/lipid multilayers prepared by drop-casting solutions of DNA and lipid mixtures onto solid surfaces. DOTAP and DOPC mixtures were used in the study with φDOTAP denoting the DOTAP content. The DNA contents are such that the systems are at their isoelectric point. The multilayers are formed via self-assembly during evaporation of the solvent. The results indicate that the short chain DNA molecules are embedded randomly in the hydrophilic headgroup regions of the lipid bilayers when φDOTAP〈50%, while the DNA molecules form a closely packaged layer inside each lipid bilayers when φDOTAP≤90%. The DNA-poor phase and DNA-rich phase coexist at intermediate DNA contents. The bilayers are distorted in the DNA-poor phase, while they are welt-ordered in the DNA-rich phase. The phase transition is driven by the lowering of the interfacial energy.

关 键 词：低角X射线衍射 DNA 磷脂 多层膜 磷脂/DNA复合体 

分 类 号：O484.5[理学—固体物理] O469[理学—物理]