Molecular Interaction and Morphology of DOPC/DPPC Monolayer

doi:10.7503/cjcu20130481

Abstract

Abstract:

Lipid membrane is widely used in simulation of the dynamic properties and structure characteristics of the biomembranes. We prepared the 1,2-dioleoy-sn-glycero-3-phosphocholine(DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine(DPPC)(1:1, molar ratio), DOPC/DPPC/Chol(2:2:1, molar ratio) monolayers via LB technique at different surface pressures. The interaction between molecules by the thermodynamic analysis method and the morphology were observed by fluorescence microscopy and atomic force microscopy(AFM). Thermodynamic analysis results show that the interaction between DOPC and DPPC is repulsive; it can induce phase separation in monolayers. Both DOPC and DPPC interact with cholesterol by attractive interaction. When the surface pressure is >18 mN/m, the force between DPPC and cholesterol is stronger than DOPC. There is obvious phase separation in the monolayers observation by fluorescence microscopy. The DPPC-enriched micro domains take on "flower-shaped" structure, and the size became larger and larger with increasing surface pressure. Add cholesterol to DOPC/DPPC system, the monolayer changes from gel-fluid phase to fluid-disordered and fluid-ordered phase coexistence structure. The DPPC-enriched domains shape from the "flower-shaped" into a "circular". Observations by AFM verified the results of fluorescence experiments. It can be concluded that the cholesterol has a significant impact on the arrangements of DOPC/DPPC monolayers, and pressure, state of solution are also important for forming the lipid membranes.

Key words: Monolayer, Phase separation, Fluorescence microscopy, Surface pressure, Biomembrane, Cholesterol

CLC Number:

O641
O621

TrendMD:

HAO Chang-Chun, ZHANG Lei, SUN Run-Guang, ZHANG Jing, HE Guang-Xiao, YANG Jing. Molecular Interaction and Morphology of DOPC/DPPC Monolayer[J]. Chem. J. Chinese Universities, 2013, 34(10): 2340.

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