Bicellar Mixtures Containing Pluronic F68: Morphology and Lateral Diffusion from Combined SANS and PFG NMR Studies

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DOIResolve DOI: http://doi.org/10.1021/la902795h
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TypeArticle
Journal titleLangmuir
Volume26
Issue4
Pages26302638; # of pages: 8
AbstractSmall angle neutron scattering (SANS) and pulsed field gradient (PFG) nuclear magnetic resonance (NMR) diffusion measurements were applied to examine morphology and diffusion in dimyristoyl- plus dihexanoyl-phosphatidylcholine bicellar mixtures, either neutral or negatively charged, incorporating a Pluronic triblock copolymer (F68). Negatively charged bicellarmixtures, doped with dimyristoylphosphatidylglycerol (DMPG), exhibited SANS profiles consistentwith a perforated lamellar morphology for the magnetically alignable phase. Correspondingly, F68 diffusion in this magnetically aligned phase was normal Gaussian, in that the mean square displacements increased linearly with the experimental diffusion time, with a lateral diffusion coefficient of 1.9x10-11m2 s-1 consistent with a lipid bilayer inserted configuration. Neutral bicellar mixtures, that is, lacking DMPG, in contrast, displayed SANS profiles characteristic of ribbons arranged in such a fashion as to produce extended lamellae.Within the lamellae, the ribbons exhibited an in-plane periodicity (interribbon) of between 120 and 140A ° .Correspondingly,F68 diffusionwas non-Gaussian, exhibiting a square root diffusion time dependence of the mean square displacement indicative of one-dimensional curvilinear diffusion. The presence or absence ofDMPG, rather than of F68, dictated the ribbon versus lamellarmorphology, with F68 reflecting this difference via its lateral diffusion behavior. Although ribbons have been reported previously, this is the first study to show that they aggregate, most likely into extended lamellar sheets, and eventually fold into multilamellar vesicles.
Publication date
LanguageEnglish
AffiliationNRC Canadian Neutron Beam Centre; National Research Council Canada
Peer reviewedYes
NPARC number16984923
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Record identifiere51e1c5f-a52f-4c2b-ba10-4fb1e4549baf
Record created2011-03-08
Record modified2016-05-09
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