title: Stimuli responsive polymorphism of C12NO/DOPE/DNA complexes: Effect of pH, temperature and composition.
abstract: N,N-dimethyldodecylamine-N-oxide (C12NO) is a surfactant that may exist either in a neutral or cationic protonated form depending on the pH of aqueous solutions. Using small angle X-ray diffraction (SAXD) we observe the rich structural polymorphism of pH responsive complexes prepared due to DNA interaction with C12NO/dioleoylphosphatidylethanolamine (DOPE) vesicles and discuss it in view of utilizing the surfactant for the gene delivery vector of a pH sensitive system. In neutral solutions, the DNA uptake is low, and a lamellar Lα phase formed by C12NO/DOPE is prevailing in the complexes at 0.2≤C12NO/DOPE<0.6 mol/mol. A maximum of ~30% of the total DNA volume in the sample is bound in a condensed lamellar phase LαC at C12NO/DOPE=1 mol/mol and pH7.2. In acidic conditions, a condensed inverted hexagonal phase HIIC was observed at C12NO/DOPE=0.2 mol/mol. Commensurate lattice parameters, aHC≈dLC, were detected at 0.3≤C12NO/DOPE≤0.4 mol/mol and pH=4.9-6.4 suggesting that LαC and HIIC phases were epitaxially related. While at the same composition but pH~7, the mixture forms a cubic phase (Pn3m) when the complexes were heated to 80°C and cooled down to 20°C. Finally, a large portion of the surfactant (C12NO/DOPE>0.5) stabilizes the LαC phase in C12NO/DOPE/DNA complexes and the distance between DNA strands (dDNA) is modulated by the pH value. Both the composition and pH affect the DNA binding in the complexes reaching up to ~95% of the DNA total amount at acidic conditions.
authors: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, Odbojárov 10, 832 32 Bratislava, Slovakia. Electronic address: hubcik@fpharm.uniba.sk.
authors: Lukáš
authors: L
authors: Hubčík
authors: HASYLAB at DESY, Notkestr. 85, D-22607 Hamburg, Germany.
authors: Sergio S
authors: SS
authors: Funari
authors: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, Odbojárov 10, 832 32 Bratislava, Slovakia.
authors: Petra
authors: P
authors: Pullmannová
authors: Department of Chemical Theory of Drugs, Faculty of Pharmacy, Comenius University, Odbojárov 10, 83232 Bratislava, Slovakia.
authors: Ferdinand
authors: F
authors: Devínsky
authors: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, Odbojárov 10, 832 32 Bratislava, Slovakia.
authors: Daniela
authors: D
authors: Uhríková
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004123:Dimethylamines / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008081:Liposomes; D050866:Liquid Crystals; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D053838:Scattering, Small Angle; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014162:Transfection / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D004123:Dimethylamines; D008081:Liposomes; D010714:Phosphatidylethanolamines; D013501:Surface-Active Agents; C094877:dioleoyl phosphatidylethanolamine; C014518:dodecyldimethylamine oxide; D004247:DNA
keywords: Cationic liposome; DNA; N,N-dimethyldodecylamine-N-oxide; Small angle X-ray diffraction; pH responsive polymorphism