Thermodynamic behavior of D-sphingosine/cholesterol monolayers and the topography observed by AFM

• 来源期刊: 中国科学B辑（英文版）
• 年，卷（期）: 2009,（2）
• 页码范围: 219-225
• 页数: 7页
• 语种: 英文
• DOI: 10.1007/s11426-008-0144-y

摘要

Lipid rafts are of a dynamic microdomain structure found in recent years, enriched in sphingolipids, cholesterol and particular proteins. The change of structure and function of lipid rafts could result in many diseases. In this work, the monolayer behavior of mixed systems of D-sphingosine with choles-terol was investigated in terms of the mean surface area per molecule (Am), excess molecular area (△Aex), surface excess Gibbs energy (△Gex), interaction parameter (ω) activity coefficients (f1 and f2) as well as elasticity (Cs-1) of formed films. The deposited Langmuir-Blodgett (LB) monolayers were inves-tigated with atomic force microscopy (AFM). Thermodynamic analysis indicates △Aex and △Gex in the binary systems with negative deviations from the ideal behavior, suggesting attractive interaction be-tween molecules. The stability, elasticity and activity coefficients show a marked dependence on the mole faction of D-sphingosine. The results of observation by AFM show that the single D-sphingosine molecular film took on small granule structure. When mixing the D-sphingosine and cholesterol at dif-ferent ratios, the mixed films transform from the chains structure to larger slice and net coexisting structure with the increasing of the cholesterol content. In the end, pure cholesterol forms more ag-gregated structure. AFM experiments effectively support the above findings and interpretation.