Alkyl Chain Ordering of Asymmetric Phosphatidyicholines Adsorbed at a Liquid-Liquid Interface
Technical rept. 1 Mar 97-31 May 98
OREGON UNIV EUGENE DEPT OF CHEMISTRY
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Interfacial adsorption and desorption of phosphatidylcholine PC monolayers is an important mechanism by which complex biological systems dynamically control physical and biochemical surface properties. We present vibrational spectroscopic investigations of hydrocarbon chain ordering in PC monolayers adsorbed from aqueous solution to an oil i.e. carbon tetrachloride-water interface as a quantitative measure of molecular-level organization pertinent to the surface characteristics displayed by these films. In a series of saturated symmetric and asymmetric chain PCs, both symmetric PCs with 16 or fewer carbons per acyl chain and highly asymmetric PCs produced relatively disordered films at the liquid-liquid interface. The longest chain PCs studied, 1,2-distearoyl-sn-PC C18C18, 1-stearoyl-2-palmitoyl-sn-PC C18C18 and 1-palmitoyl-2-stearoyl-sn-PC C18C18, formed well-ordered crystalline phase monolayers at room temperature. The results can be explained in terms of enhanced chain-chain interactions among the longer, nearly symmetric hydrocarbon chains which occur only in the absence of intercalating solvent. Properties of the neat oil-water interface which may influence the formation of these well-ordered monolayer phases are discussed.
- Physical Chemistry