Document Detail

Spontaneous formation of DPPC monolayers at aqueous/vapor interfaces and the impact of charged surfactants.
MedLine Citation:
PMID:  18590699     Owner:  NLM     Status:  MEDLINE    
Surface tensiometry and vibrational sum-frequency spectroscopy were used to examine the structure and organization in phospholipid monolayers at the aqueous/vapor interface in the absence and in the presence of simple, charged surfactants. 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was the phospholipid employed in these studies and surfactants included sodium dodecyl sulfate (SDS) and dodecyl trimethyl ammonium bromide (DTAB). DPPC spontaneously spreads on a pure water (pH=5.5) surface to form monolayers as evidenced by an equilibrium spreading pressure (ESP) of 7.9+/-2.3 mN/m and a clearly resolved vibrational spectrum. Low concentrations of surfactants inhibit the spreading of DPPC and result in significantly lower ESP values. Anionic and cationic surfactants at higher concentrations have opposite effects on monolayer organization; SDS creates well-organized monolayers while DTAB leads to poor organization of lipid molecules. Surface-specific vibrational spectra showed that high concentrations of charged surfactants (>or=100 microM) lead to accumulation of net surface charges as evidenced by destructive and constructive interferences. Selectively deuterating surfactants results in changes in vibrational band intensities and phases enabling assignment of relative orientations of equivalent functional groups belonging to the lipid and surfactant.
Süleyman Z Can; Chia Fang Chang; Robert A Walker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2008-06-11
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1778     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-22     Completed Date:  2008-12-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  2368-77     Citation Subset:  IM    
Department of Chemistry and Biochemistry, University of Maryland, College Park, College Park, MD 20742, USA.
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MeSH Terms
1,2-Dipalmitoylphosphatidylcholine / chemistry*
Lipids / chemistry
Membranes / chemistry
Molecular Structure
Phospholipids / chemistry
Surface Properties
Surface Tension
Surface-Active Agents / chemistry*
Water / chemistry
Grant Support
//Howard Hughes Medical Institute
Reg. No./Substance:
0/Lipids; 0/Phospholipids; 0/Surface-Active Agents; 2644-64-6/1,2-Dipalmitoylphosphatidylcholine; 7732-18-5/Water

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