title: Thermally-induced order-order transition of DNA-cationic surfactant complexes.
abstract: Polyanionic DNA interacts with cationic amphiphiles to form electrostatic complexes exhibiting rich self-assembled structures. This type of complex has been considered as a nonviral carrier in gene therapy and as a template for nanostructure construction. Here we report a thermally-induced phase transition of the complexes of DNA with the mixtures of a cationic surfactant, dodecyltrimethyl bromide (DTAB), and a neutral lipid, dioleoylphosphatidylethanolamine (DOPE), in fully hydrated state. An order-order transition between a multilamellar (L(c)alpha) phase and an inverted hexagonal (H(c)II) phase was found to occur with the transition temperature adjustable by the DTAB-to-DNA base pair molar ratio (x) and DOPE-to-DTAB molar ratio (m). The stability of the L(c)alpha phase was enhanced at lower m and x, as the L(c)alpha-to-H(c)II transition temperature increased with the decreases of these two parameters. The suppression of -to- transition at lower x was attributed to the lower entropic gain from the counterion release due to the presence of uncomplexed DNA in the bulk solution.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu 30013, Taiwan.
authors.forename: Wei-Long
authors.initials: WL
authors.lastname: Hsu
authors.forename: Yen-Cheng
authors.initials: YC
authors.lastname: Li
authors.forename: Hsin-Lung
authors.initials: HL
authors.lastname: Chen
authors.forename: Willisa
authors.initials: W
authors.lastname: Liou
authors.forename: U-Ser
authors.initials: US
authors.lastname: Jeng
authors.forename: Hsien-Kuang
authors.initials: HK
authors.lastname: Lin
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Liu
authors.forename: Chain-Shu
authors.initials: CS
authors.lastname: Hsu
mesh_terms: D002412:Cations / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010714:Phosphatidylethanolamines / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012996:Solutions; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D002412:Cations; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D013501:Surface-Active Agents; C013912:decyltrimethylammonium; D004247:DNA