1，2-二棕榈酰-sn-甘油-3-磷酸胆碱双层膜界面性质的纳米力学表征
Nanomechanical Characterization of the Interfacial Properties of Bilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine
摘要：
我们研究了在凝胶相中的1，2-dipalmitoyl-sn-glycero-3-phosphocholine双分子层的力学性质，通过使用峰值力敲击与定量纳米力学映射。我们研究了氧化硅表面上支持的干燥和含水双层和脂质体。我们报告的观察一个显着的基板上测得的杨氏模量的支持双层堆栈的高度增加而减少。相比之下，对于支撑的水性脂质体的顶部双层，未观察到明显的底物效应，然而，其受样品的表面曲率的影响。干样品和水溶液样品之间的粘附力呈现定量差异，前者主要由毛细管效应和后者由尖端和基底之间的非接触相互作用。堆叠的双层的机械性能揭示了两个不同的制度之间的阈值，为下部和上部的堆栈，这表明系统的可塑性的变化。阈值受应用的设定点和样品老化的影响。我们建议，它产生于接触磷脂双分子层，这似乎有一个主要的影响双层的响应外部机械应力的头基之间的水合水的薄层的存在。
英文摘要：
We investigate the mechanical properties of bilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine in the gel phase by using peak force tapping with quantitative nanomechanical mapping. We study both dry and aqueous bilayers and liposomes supported on the oxidized silicon surface. We report the observation of a marked substrate effect on the measured Young modulus of supported bilayer stacks which decreases as the height of the stack increases. In contrast a clear substrate effect is not observed for the top bilayer of supported aqueous liposomes, which is however affected by the surface curvature of the sample. Adhesion forces present quantitative differences between dry and aqueous samples, with the former being dominated by capillary effects and the latter by non-contact interactions between tip and substrate. The mechanical properties of stacked bilayers reveal a threshold between two different regimes, for the lower portion and the upper portion of the stack, that shows a change in the plasticity of the system. The threshold is affected by applied setpoint and aging of the sample. We propose that it arises from the presence of thin layers of hydration water between the headgroups of contacting phospholipid bilayers, which appears to have a major effect on the response of the bilayer to an external mechanical stress.
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