2024-03-28T13:33:03Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/533752016-02-17T09:06:07Zcom_10261_86com_10261_1col_10261_339
00925njm 22002777a 4500
dc
Rodríguez-Pulido, Alberto
author
Martín-Molina, Alberto
author
Rodríguez-Beas, César
author
Llorca, Óscar
author
Aicart, Emilio
author
Junquera, Elena
author
2009-11-26
The compaction of DNA by cationic liposomes constituted by a mixture of a cationic lipid, dioctadecyldimethylammonium bromide (DODAB), and a zwitterionic lipid, 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) or 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), has been evaluated by means of experimental studies (electrophoretic mobility, conductometry, cryogenic electron transmission microscopy or cryo-TEM, and fluorescence spectroscopy) as well as theoretical calculations. This information reveals that DODAB/DOPE and DODAB/DLPC liposomes are mostly spherical and unilamellar, with a mean diameter of around 70 and 61 nm, respectively, a bilayer thickness of 4.5 nm, and gel-to-fluid transition temperatures, Tm, of around 19 and 28 °C, respectively. Their positively charged surfaces efficiently compact the negatively charged DNA by means of a strong entropically driven surface interaction that yields DODAB/DOPE−DNA and DODAB/DLPC−DNA lipoplexes as confirmed by zeta potential and ethidium bromide fluorescence intercalation assays. These experiments have permitted as well the evaluation of the different microenvironments of varying polarity of the DNA helix, liposomes, and/or lipoplexes. DODAB/DOPE−DNA and DODAB/DLPC−DNA lipoplexes have been characterized by isoneutrality ratios (L/D) of around 4.7 and 4.8, respectively, a more fluid membrane than that of the parent liposomes, and Tm around 24 and 28 °C, respectively, as revealed by fluorescence anisotropy. Cryo-TEM micrographs reveal a rich scenario of nanostructures and morphologies, from unilamellar DNA-coated liposomes to multilamellar lipoplexes passing through cluster-like structures. Phase diagrams (aggregation and re-entrant condensation phenomena), calculated by means of a phenomenological theory, have confirmed the experimental concentration domains and the isoneutrality conditions. The influence of helper lipid in the compaction process, as well as the optimum choice among those herein chosen, has been analyzed
Journal of Physical Chemistry 113(47):15648-15661(2009)
1520-6106
http://hdl.handle.net/10261/53375
10.1021/jp906777g
1520-5207
A theoretical and experimental approach to the compaction process of DNA by dioctadecyldimethylammonium bromide/zwitterionic mixed liposomes