Cui Li, Chen Daoyong, Zhu Lei
Polymer Program, Institute of Materials Science and Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269, USA.
ACS Nano. 2008 May;2(5):921-7. doi: 10.1021/nn800177v.
In this work, a novel cube-shaped cationic lipid based on the imidazolium salt of polyhedral oligomeric silsesquioxane (POSS) was complexed with double-stranded DNA. Because of the negative spontaneous curvature of the cationic POSS imidazolium lipid, an inverted hexagonal phase resulted above the melting point of POSS crystals. Depending on the competition between the crystallization of POSS molecules and the negative spontaneous curvature of cationic POSS imidazolium lipids, different self-assembled phase morphologies were obtained. A lamellar phase was obtained when the POSS crystallization was relatively slow. When the POSS crystallization was fast, an inverted hexagonal phase was obtained with POSS lamellar crystals grown in the interstitials of DNA cylinders. On the basis of a circular dichroism study, double-stranded DNA adopted the B-form helical conformation in the inverted hexagonal phase, whereas the helical conformation was largely destroyed in the lamellar phase.
在这项工作中，一种基于多面体低聚倍半硅氧烷（POSS）咪唑盐的新型立方体形阳离子脂质与双链DNA复合。由于阳离子POSS咪唑脂质的负自发曲率，在POSS晶体熔点以上形成了反相六角相。根据POSS分子结晶与阳离子POSS咪唑脂质的负自发曲率之间的竞争，获得了不同的自组装相形态。当POSS结晶相对较慢时，得到层状相。当POSS结晶较快时，得到反相六角相，其中POSS层状晶体生长在DNA圆柱体的间隙中。基于圆二色性研究，双链DNA在反相六角相中采用B型螺旋构象，而在层状相中螺旋构象被大大破坏。
