Monolayer Properties of 1,3-Diamidophospholipids

Autor: lllya A. Fedotenko, Cristina Stefaniu, Gerald Brezesinski, Andreas Zumbuehl
Rok vydání: 2013
Předmět:
Zdroj: Langmuir
LANGMUIR
ISSN: 1520-5827
0743-7463
DOI: 10.1021/la401692e
Popis: While nature provides an endless variety of phospholipids presenting hydrolyzable ester linkages for the 12 positioned hydrocarbon tails we designed and synthesized 13 diamidophospholipids which contain stable fatty acid amides. These new phospholipids form faceted unilamellar vesicles with mechanosensitive properties. Aiming to understand the mechanism responsible for this behavior at a molecular level we investigated the 13 diamidophospholipid family in monolayers a simplified model membrane system. Langmuir isotherms combined with in situ grazing incidence X ray diffraction (GIXD) specular X ray reflectivity (XR) and infrared reflection absorption spectroscopy (IRRAS) allowed the characterization of the monolayers from a structural and thermodynamical point of view. The existence of strong headgroup interactions due to the formation of a hydrogen bonding network was clearly revealed by IRRAS and by the high rigidity of the monolayers. GIXD showed that only the longer chain compounds of the series (Pad PC Pad (13 dipalmitamidopropan 2 phosphocholine) and Sad PC Sad (13 distearamidopropan 2 phosphocholine) were able to form ordered monolayers. The chains are strongly tilted in a rigid lattice formed due to these hydrogen bonding interactions between the headgroups. The thermodynamical analysis leads to a critical temperature of the monolayer which is clearly different from the main phase transition temperature in bulk indicating that there must be a different structural arrangement of the 13 diamidophospholipids in monolayers and in bilayers. © 2013 American Chemical Society.
Databáze: OpenAIRE
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