Morphology of dipalmitoyl phosphatidyl choline (DPPC)-cholesterol (Chol) mixed monolayer formed on water surface by dropping method was investigated using surface tension measurement (STm), Brewster angle microscopy (...Morphology of dipalmitoyl phosphatidyl choline (DPPC)-cholesterol (Chol) mixed monolayer formed on water surface by dropping method was investigated using surface tension measurement (STm), Brewster angle microscopy (BAM), and fluorescence microscopy (FM). STm showed strong condensation effect of Chol in fluidic DPPC monolayer. Excess area (S<sub>ex</sub>) from mean mixing state of DPPC and Chol was about twice larger than that by general compression method in the range from xC = 0.2 to 0.4 (xC: mole fraction of Chol). BAM and FM images showed clearly that the fluidic DPPC monolayer changed to condensed rigid monolayer due to the condensation effect of Chol. At more than xC = 0.3 DPPC-Chol mixed monolayer changed to condensed state similar to the Chol monolayer. These results support previous reports by compression method that Chol molecule demonstrates the strong condensation effect to the fluidic monolayer and also indicate that dropping method enables to form unique monolayer on the water surface.展开更多
Preparation of DPPC lipid monolayer in water trough has been done by dropping method and compared with compression method. Monolayer was studied by surface pressure isotherm, fluorescence microscopy, Brewster angle mi...Preparation of DPPC lipid monolayer in water trough has been done by dropping method and compared with compression method. Monolayer was studied by surface pressure isotherm, fluorescence microscopy, Brewster angle microscopy, and infrared external reflection spectroscopy. Results of these measurements showed that dropping method gave better results compared to compression method. In dropping method, transition from liquid expanded state to liquid condensed is gradual compared to sharp one in compressed method. During monolayer formation, adjustment and interaction between hydrophilic part of lipid and water and among hydrophobic part of lipid molecule are slow, stable, and more natural as worked out from surface area versus pressure isotherm. At a given molecular area, surface pressure is less compared to compression method thus monolayer is in more fluidic state in dropping method than compression method. The observation was supported by all techniques described above.展开更多
文摘Morphology of dipalmitoyl phosphatidyl choline (DPPC)-cholesterol (Chol) mixed monolayer formed on water surface by dropping method was investigated using surface tension measurement (STm), Brewster angle microscopy (BAM), and fluorescence microscopy (FM). STm showed strong condensation effect of Chol in fluidic DPPC monolayer. Excess area (S<sub>ex</sub>) from mean mixing state of DPPC and Chol was about twice larger than that by general compression method in the range from xC = 0.2 to 0.4 (xC: mole fraction of Chol). BAM and FM images showed clearly that the fluidic DPPC monolayer changed to condensed rigid monolayer due to the condensation effect of Chol. At more than xC = 0.3 DPPC-Chol mixed monolayer changed to condensed state similar to the Chol monolayer. These results support previous reports by compression method that Chol molecule demonstrates the strong condensation effect to the fluidic monolayer and also indicate that dropping method enables to form unique monolayer on the water surface.
文摘Preparation of DPPC lipid monolayer in water trough has been done by dropping method and compared with compression method. Monolayer was studied by surface pressure isotherm, fluorescence microscopy, Brewster angle microscopy, and infrared external reflection spectroscopy. Results of these measurements showed that dropping method gave better results compared to compression method. In dropping method, transition from liquid expanded state to liquid condensed is gradual compared to sharp one in compressed method. During monolayer formation, adjustment and interaction between hydrophilic part of lipid and water and among hydrophobic part of lipid molecule are slow, stable, and more natural as worked out from surface area versus pressure isotherm. At a given molecular area, surface pressure is less compared to compression method thus monolayer is in more fluidic state in dropping method than compression method. The observation was supported by all techniques described above.
