Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai - 400076 India.
J Phys Chem B. 2009 Oct 22;113(42):13805-10. doi: 10.1021/jp902909z.
Vesicles prepared from surfactant sodium dioctyl sulfosuccinate (AOT) were characterized by micropipet aspiration for determining membrane bending rigidity and area expansion modulus and mechanism of rupture. Unilamellar vesicles (ULV) and multilamellar vesicles (MLV) were studied. The mechanical properties calculated using micropipet aspiration for ULV were found to be 5-10 k(B)T, K(a) = 100 +/- 20 mN/m and for MLV were 8-15 k(B)T, K(a) = 120 +/- 30 mN/m. These properties fall with the range of lipid (PC) membrane measurements (values). However, the membrane rigidity of multilamellar vesicles was found to be approximately 3 times larger than that of unilamellar vesicles. The apparent area expansion moduli of multilamellar vesicles are of the order 1.4 times, sustained far greater areal strain before rupture compared to that of unilamellar vesicles. A dynamic structural change in MLV is demonstrated upon stress by micropipet aspiration. MLV at stress undergoes various stages of deformation. The fluctuation in size and shape of MLV led to separation of bilayers from the stack and decrease in vesicle diameter facilitating in formation of new equilibrium MLV, for it to sustain the specified membrane tension, a new mechanism that is demonstrated experimentally.
用玻璃微吸管抽吸法从表面活性剂二辛基琥珀酸磺酸钠（AOT）中制备囊泡，用于测定膜弯曲刚度和面积扩张模量以及破裂机制。研究了单层囊泡（ULV）和多层囊泡（MLV）。使用玻璃微吸管抽吸法计算出的 ULV 的力学性能为 5-10 k（B）T，K（a）= 100 +/- 20 mN/m，而 MLV 的力学性能为 8-15 k（B）T，K（a）= 120 +/- 30 mN/m。这些性质在脂质（PC）膜测量值的范围内。然而，多层囊泡的膜刚性被发现大约是单层囊泡的 3 倍。多层囊泡的表观面积扩张模量约为 1.4 倍，在破裂前能承受更大的面积应变。玻璃微吸管抽吸对 MLV 施加应力时，会发生动态结构变化。MLV 在应力作用下经历各种变形阶段。MLV 的大小和形状的波动导致双层从堆叠中分离，囊泡直径减小，有利于新的平衡 MLV 的形成，因为它要维持指定的膜张力，这是一种实验证明的新机制。
