Vesicles versus membrane fragments in DODAC suspensions

The authors report on the organization properties of DODAC molecules in water solutions. The authors have measured a value of 8.3 {plus minus} 0.5% for the encapsulation efficiency of DODAC for 5NS, a membrane adsorbed probe. This value, which is consistent with most published ones, implies that ves...

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Bibliographic Details
Published in:Journal of physical chemistry (1952) 1990, Vol.94 (2), p.796-801
Main Authors: Pansu, Robert B, Arrio, Bernard, Roncin, Jacques, Faure, Jean
Format: Article
Language:English
Subjects:
140505 > Solar Energy Conversion-- Photochemical, Photobiological, & Thermochemical Conversion-- (1980-)
AMMONIUM CHLORIDES
AMMONIUM COMPOUNDS
AMMONIUM HALIDES
AQUEOUS SOLUTIONS
Chemistry
CHLORIDES
CHLORINE COMPOUNDS
Colloidal gels. Colloidal sols
Colloidal state and disperse state
CONFORMATIONAL CHANGES
CONVERSION
DATA
DATA ANALYSIS
DISPERSIONS
ENERGY CONVERSION
Exact sciences and technology
EXPERIMENTAL DATA
General and physical chemistry
HALIDES
HALOGEN COMPOUNDS
INFORMATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
LIGHT SCATTERING
MEASURING INSTRUMENTS
MEASURING METHODS
MEMBRANES
MIXTURES
NUMERICAL DATA
ORGANIZATIONAL MODELS
SCATTERING
SOLAR ENERGY
SOLAR ENERGY CONVERSION
SOLUTIONS 400201 > Chemical & Physicochemical Properties
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Summary:The authors report on the organization properties of DODAC molecules in water solutions. The authors have measured a value of 8.3 {plus minus} 0.5% for the encapsulation efficiency of DODAC for 5NS, a membrane adsorbed probe. This value, which is consistent with most published ones, implies that vesicles are only a minor fraction in DODAC suspensions. Light-scattering experiments show that most of the DODAC molecules are organized in small open structures: flat dislike bilayers. These membrane fragments are formed by destruction of the vesicles during the sonication process. Upon annealing or after addition of Fe(CN){sub 6}{sup 4{minus}}, fragments gather to form a population of vesicles with a narrow size distribution. This size monodispersity has been rationalized by geometric models, assuming thermodynamic equilibrium. But the authors studies show that, as phospholipid vesicles, DODAC suspensions are not in thermodynamic equilibrium. Models that consider both the energetics and the kinetics of the vesicles formation have been proposed by Lasic and by Fromherz. The formation of a size paucidisperse population of vesicles from a size polydisperse population of membrane fragments, that they observe, is the first experimental evidence supporting such models.
ISSN:0022-3654
1541-5740
DOI:10.1021/j100365a053