### 鞘氨醇与DPPC, DPPE单层膜的热力学特性及形态观察

1. (a陕西师范大学物理学与信息技术学院生物物理与生物医学工程研究所 西安 710062)
(b陕西师范大学食品工程与营养科学学院 西安 710062)

• 投稿日期:2008-10-23 修回日期:2008-12-22 发布日期:2009-08-14
• 通讯作者: 孙润广

### A Monolayer Study on Thermodynamic Behavior and Morphology of D-Sphingosine with DPPC and DPPE

Sun, Runguang*,a Hao, Changchuna Chang, Yiguanga Zhang, Jingb Niu, Chunlinga

1. (a Laboratory of Biophysics and Biomedical Engineering, College of Physics and Information Technology,
Shaanxi Normal University, Xi’an 710062)
(b College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi’an 710062)
• Received:2008-10-23 Revised:2008-12-22 Published:2009-08-14
• Contact: SUN Run-Guang

As the precursor of sphingolipids, sphingosine is one of important constituents of cell membranes. In this work, the thermodynamic behavior of mixed systems of D-sphingosine with 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) has been investigated by analyzing the data of surface pressure-mean molecular area isotherms. The deposited Langmuir-Blodgett (LB) monolayers of different ratios were investigated with atomic force microscopy (AFM) under certain surface pressure. The results show that: (1) in D-sphingosine/DPPC system, the excess molecular area and excess Gibbs energy took on negative deviations from the ideal behavior at D-sphingo- sine ratios of XD-Sph＝0.2, 0.4, 0.6 and positive values at XD-Sph＝0.8; and (2) as for D-sphingosine/DPPE systems, the excess molecular area and excess Gibbs energy displayed negative values at the surface pressure of π＜25 mN&#8226;m－1, and positive at π≥25 mN&#8226;m－1. The interaction of mixtures was determined by molecular area and Gibbs energy. The negative deviations from ideality suggest attractive interaction between molecules, with aggregating phenomenon. Furthermore, positive deviation from linearity indicates repelling interaction between the two compounds, inducing phase separation. Moreover, the mixed monolayer is more stable if the value of excess Gibbs energy is lower. The compression and AFM experiments support the above findings effectively as well as interpretation.