Linked Life Data

17500555

Source:http://linkedlifedata.com/resource/pubmed/id/17500555

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
22
pubmed:dateCreated
2007-5-31
pubmed:abstractText
The effect of glycerol on the permeability of vesicle membranes of a siloxane surfactant, the block copolymer polyethyleneoxide-b-polydimethylsiloxane-polyethyleneoxide, (EO)15-(DMS)15-(EO)15, was studied with freeze-fracture transmission electron microscopy (FF-TEM) and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy. The FF-TEM results show that, in pure water, the surfactant can form small vesicles with diameters of less than 25 nm, as well as a few multilamellar vesicles with diameters larger than 250 nm. Gradual substitution of water with glycerol to a glycerol content of 40% leads to significant structural transformations: small vesicles are gradually swollen, and large multilamellar vesicles disappear. A glycerol content of 60% results in the complete disintegration of the vesicles into membrane fragments. PFG-NMR measurements indicate that the vesicle membrane does not represent an effective barrier for water molecules on the NMR time scale; hence, the average residence time of water in the encapsulated state is below tau b = 2 ms. In contrast, the average residence time of glycerol molecules in the encapsulated state can be as large as tau b = 910 ms. The permeability of the vesicle membrane increases with increasing glycerol concentration in the solvent: At a concentration of 40%, the residence time tau b is lowered to approximately 290 ms. After vesicle destruction at higher glycerol concentrations, a small glycerol fraction is still bound by membrane fragments that are formed after the disintegration of the vesicles.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1520-6106
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
111
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6161-6
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Molecular exchange through the vesicle membrane of siloxane surfactant in water/glycerol mixed solvents.
pubmed:affiliation
BZKG, Universität Bayreuth, Gottlieb-Keim-Strasse 60, D-95448 Bayreuth, Germany. yun.yan@wur.nl
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't