Linked Life Data

17464955

Source:http://linkedlifedata.com/resource/pubmed/id/17464955

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2007-5-30
pubmed:abstractText
The molecular exchange of tracer molecules through the membranes of dispersed vesicles of the block copolymer poly(2-vinylpyridine-block-ethylene oxide) was studied by using NMR spectroscopy combined with pulsed field gradients. The hydrodynamic radius of the tracer molecules was varied systematically to obtain a permeability profile of the vesicle membrane. In addition, the effect of system parameters, such as temperature, pH value, vesicle size, and thickness of the vesicle membrane, was studied. In the case of rapid exchange with average residence times significantly smaller than 10 s, the permeation is observed under equilibrium conditions and the data are analyzed by using a simple analytical approach. For slow exchange processes with average residence times above 10 s, the permeation is monitored in a time-resolved measurement under nonequilibrium conditions. Generally, the transmembrane exchange rate of the tracer clearly depends on its hydrodynamic radius. The characteristics of this dependence indicate the presence of two different mechanisms of membrane penetration, one dominating for smaller and one for larger tracer molecules, respectively. The exchange rate also shows a significant dependence on the bilayer thickness and on the vesicle diameter. By contrast, no variation of the membrane permeability with the temperature or the pH value could be detected as long as the vesicles remain stable.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1613-6829
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
3
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1074-83
pubmed:dateRevised
2008-4-17
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Molecular exchange through membranes of poly(2-vinylpyridine-block-ethylene oxide) vesicles.
pubmed:affiliation
University Duisburg-Essen, Physical Chemistry, 45141 Essen, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't