Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.
Langmuir. 2011 Jun 21;27(12):7672-80. doi: 10.1021/la2003172. Epub 2011 May 27.
Plasma membrane tension, produced by the underlying cytoskeleton, governs many dynamic processes such as fusion, blebbing, exo- and endocytosis, cell migration, and adhesion. Here, a new protocol is introduced to model this intricate and often overlooked aspect of the plasma membrane. Lipid bilayers spanning pores of 600 nm radius were prepared by adsorption and spreading of giant unilamellar vesicles (GUVs) on moderately hydrophilic porous substrates prepared by gold-coating and subsequent self-assembly of a mercaptoethanol monolayer. Rupture of GUVs formed tens of micrometer sized pore-spanning membrane patches displaying low tension of σ ≤ 3.5 mN m(-1) and lateral diffusion constants of about 8 μm(2) s(-1). Site-specific force indentation experiments were performed to determine membrane tension as a function of lipid composition: for pure DOPC bilayers, a tension of 1.018 ± 0.014 mN m(-1) was measured, which was increased by the addition of cholesterol to 3.50 ± 0.15 mN m(-1). Compared to DOPC, POPC bilayers displayed a larger tension of 2.00 ± 0.09 mN m(-1). Addition and subsequent partitioning of 2-propanol was shown to significantly reduce the membrane tension as a function of its concentration.
质膜张力由其下的细胞骨架产生，它控制着许多动态过程，如融合、起泡、外排和内吞、细胞迁移和黏附。本文介绍了一种新的方案来模拟质膜这一复杂且常被忽视的方面。通过吸附和在适度亲水的多孔基底上伸展巨大的单层囊泡（GUV）来制备跨越半径为 600nm 的孔的脂质双层，该多孔基底是通过金涂层和随后的巯基乙醇单层的自组装制备的。GUV 的破裂形成了数十微米大小的孔跨膜斑块，显示出低张力σ≤3.5mN m(-1)和大约 8μm(2) s(-1)的侧向扩散常数。进行了特定位置的力压痕实验以确定脂质组成的膜张力：对于纯 DOPC 双层，测量到的张力为 1.018±0.014mN m(-1)，添加胆固醇后增加到 3.50±0.15mN m(-1)。与 DOPC 相比，POPC 双层的张力更大，为 2.00±0.09mN m(-1)。添加和随后分配 2-丙醇被证明可以显著降低膜张力，这取决于其浓度。
