Hu Yufang, Meleson Kieche, Israelachvili Jacob
Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California, USA.
Biophys J. 2006 Jul 15;91(2):444-53. doi: 10.1529/biophysj.106.081000. Epub 2006 Apr 21.
This [corrected] article outlines the results from a combined experimental and theoretical study on the properties of circular domains in a mixed Langmuir monolayer at thermodynamic equilibrium. The mixed monolayer consisted of a binary mixture of dimyristoyl-phosphatidyl-choline and dihydrocholesterol. A long-term fluorescence microscopy study of these domains was carried out over the course of approximately 60 h. Image analysis of the domains over time revealed that the domains ripened slowly with an [corrected] increase in mean domain radius and a [corrected] decrease in domain number density. At the end of the measurement, the domains remained polydisperse, and true thermodynamic equilibrium was not reached. Theoretically, collective thermodynamic equilibrium properties such as mean domain size and size distribution were calculated by combining micelle self-assembly theory and the "equivalent dipole" model for the self-energy of two-dimensional domains. The calculations predicted existence of finite-sized circular domains at equilibrium. This suggests that equilibrium circular monolayer domains of single- or multicomponent lipids with a finite size distribution should form only at very limited experimental conditions. Both the predicted mean domain size and size distribution are strongly affected by line tension and dipole moment density difference. A comparison between the theoretical and experimental results is made.
这篇[修正后的]文章概述了在热力学平衡条件下对混合朗缪尔单分子层中圆形区域性质进行的实验与理论相结合的研究结果。该混合单分子层由二肉豆蔻酰磷脂酰胆碱和二氢胆固醇的二元混合物组成。对这些区域进行了约60小时的长期荧光显微镜研究。随着时间对区域进行图像分析发现，区域会缓慢熟化，平均区域半径[修正后]增加，区域数密度[修正后]降低。在测量结束时，区域仍保持多分散性，未达到真正的热力学平衡。从理论上讲，通过结合胶束自组装理论和二维区域自能的“等效偶极子”模型，计算了诸如平均区域大小和尺寸分布等集体热力学平衡性质。计算预测了平衡时有限大小圆形区域的存在。这表明单组分或多组分脂质的平衡圆形单分子层区域，只有在非常有限的实验条件下才会形成。预测的平均区域大小和尺寸分布都受到线张力和偶极矩密度差的强烈影响。并对理论和实验结果进行了比较。
