Effect of cation enrichment on dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface
Publikation: Beitrag in Fachzeitschrift › Forschungsartikel › Beigetragen › Begutachtung
Beitragende
Abstract
The effect of highly concentrated salt solutions of marine-relevant cations (Na+, K+, Mg2+, and Ca2+) on Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) was investigated by means of surface pressure-area isotherms, Brewster angle microscopy (BAM), and infrared reflection-absorption spectroscopy (IRRAS). It was found that monovalent cations and Mg2+ have similar phase behavior, causing DPPC monolayers to expand, while Ca2+ induces condensation. All cations disrupted the surface morphology at high cation concentration, resulting in decreased reflectivity from the monolayer. Monolayer refractive index was calculated from BAM image intensity in the liquid condensed phase and decreased with increasing cation concentration, which suggests that orientation of the alkyl chains change. Monovalent ions increase ordering of the alkyl chains, more than divalents, yet have little interaction with the DPPC headgroup. Mg2+ induces gauche defects in the alkyl chain and increases headgroup hydration at low lipid coverage but increases chain ordering and dehydrates the headgroup at high lipid coverage. Ca2+ orders alkyl chains and dehydrates the phosphate moiety, independent of lipid phase. At the highest salt concentration investigated, significant narrowing of the asymmetric PO2- vibrational mode occurs and is attributed to considerable dehydration of the DPPC headgroup.
Details
Originalsprache | Englisch |
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Seiten (von - bis) | 353-364 |
Seitenumfang | 12 |
Fachzeitschrift | Journal of colloid and interface science |
Jahrgang | 478 |
Publikationsstatus | Veröffentlicht - 15 Sept. 2016 |
Peer-Review-Status | Ja |
Extern publiziert | Ja |
Externe IDs
ORCID | /0000-0002-8120-8553/work/161409575 |
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Schlagworte
Ziele für nachhaltige Entwicklung
ASJC Scopus Sachgebiete
Schlagwörter
- Brewster angle microscopy (BAM), Cations, Dipalmitoylphosphatidylcholine (DPPC), Infrared reflection-absorption spectroscopy (IRRAS), Langmuir isotherms, Marine aerosols, Monolayers