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Spontaneous formation of DPPC monolayers at aqueous/vapor interfaces and the impact of charged surfactants.
Can, Süleyman Z; Chang, Chia Fang; Walker, Robert A.
Afiliação
  • Can SZ; Department of Chemistry and Biochemistry, University of Maryland, College Park, College Park, MD 20742, USA.
Biochim Biophys Acta ; 1778(10): 2368-77, 2008 Oct.
Article em En | MEDLINE | ID: mdl-18590699
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.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Tensoativos / 1,2-Dipalmitoilfosfatidilcolina Idioma: En Revista: Biochim Biophys Acta Ano de publicação: 2008 Tipo de documento: Article País de afiliação: Estados Unidos País de publicação: Holanda

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Tensoativos / 1,2-Dipalmitoilfosfatidilcolina Idioma: En Revista: Biochim Biophys Acta Ano de publicação: 2008 Tipo de documento: Article País de afiliação: Estados Unidos País de publicação: Holanda