title: Conformation transformation determined by different self-assembled phases in a DNA complex with cationic polyhedral oligomeric silsesquioxane lipid.
abstract: 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.
authors.affiliation: Polymer Program, Institute of Materials Science and Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Cui
authors.forename: Daoyong
authors.initials: D
authors.lastname: Chen
authors.forename: Lei
authors.initials: L
authors.lastname: Zhu
mesh_terms: D002412:Cations; D003460:Crystallization / Q000379:methods*; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D009690:Nucleic Acid Conformation; D017646:Organosilicon Compounds / Q000737:chemistry*; D010316:Particle Size; D044367:Phase Transition; D013499:Surface Properties
chemical_list: D002412:Cations; D046911:Macromolecular Substances; D017646:Organosilicon Compounds; D004247:DNA