Kinetics of the adhesion of DMPC liposomes on a mercury electrode. Effect of lamellarity, phase composition, size and curvature of liposomes, and presence of the pore forming peptide mastoparan X.
Kinetics of the adhesion of DMPC liposomes on a mercury electrode. Effect of lamellarity, phase composition, size and curvature of liposomes, and presence of the pore forming peptide mastoparan X.
复制标题
DMPC 脂质体在汞电极上的粘附动力学。
作者：
V. Hernández;F. Scholz
悬浮在电解质水溶液中的脂质体可以粘附在汞电极上。粘附是一个复杂的过程，从对接和打开开始，并导致扩散，最终导致形成吸附卵磷脂分子的岛屿。粘附过程可以通过计时电流法进行，并且可以进行宏观和微观动力学的详细分析，从而产生速率常数和活化参数。通过使用巨大的单层脂质体和多层脂质体，层状和脂质体的大小的影响，可以阐明在液晶，凝胶和超晶格相状态的脂质体。在相变温度以下，脂质体打开的时间常数（即，卵磷脂分子在初步接触界面脂质体上的不可逆结合|汞和与之相关的脂质体膜在该点上的崩解）显示出强烈的尺寸依赖性。然而，除了非常小的脂质体之外，该过程的活化能与尺寸无关。时间常数的尺寸依赖性是初始接触面积的尺寸依赖性的结果。铺展步骤的时间常数和活化能表现出强烈的尺寸依赖性，这可能是由于孔隙形成的速率和活化能的尺寸依赖性。孔形成对于释放包含在脂质体中的溶液是必要的。通过向脂质体悬浮液中加入孔诱导肽Mastoparan X证实了这种理解。结果表明，汞电极上的脂质体粘附的电化学研究可以作为一种仿生工具，以了解膜的性质对囊泡融合的影响。
Liposomes suspended in aqueous electrolyte solutions can adhere at mercury electrodes. The adhesion is a complex process that starts with the docking and opening and leads to a spreading, finally resulting in the formation of islands of adsorbed lecithin molecules. The adhesion process can be followed by chronoamperometry, and a detailed analysis of the macroscopic and microscopic kinetics can be performed yielding rate constants and activation parameters. By using giant unilamellar liposomes and multilamellar liposomes, the effect of lamellarity and liposome size could be elucidated for liposomes in the liquid crystalline, gel, and superlattice phase states. Below the phase transition temperature, the time constant of opening of the liposomes (i.e., the irreversible binding of the lecithin molecules on the preliminary contact interface liposome|mercury and the therewith associated disintegration of the liposome membrane on that spot) is shown to be strongly size dependent. The activation energy, however, of that process is size independent with the exception of very small liposomes. That size dependence of time constants is a result of the size dependence of the initial contact area. The time constant and the activation energies of the spreading step exhibit a strong size dependence, which could be shown to be due to the size dependence of rate and activation energy of pore formation. Pore formation is necessary to release the solution included in the liposomes. This understanding was corroborated by addition of the pore inducing peptide Mastoparan X to the liposome suspension. The obtained results show that electrochemical studies of liposome adhesion on mercury electrodes can be used as a biomimetic tool to understand the effect of membrane properties on vesicle fusion.