Han Chung-Ta, Chao Ling
Department of Chemical Engineering, National Taiwan University , Taipei 10617, Taiwan.
ACS Appl Mater Interfaces. 2014 May 14;6(9):6378-83. doi: 10.1021/am405746g. Epub 2014 Apr 23.
Supported lipid bilayer platforms have been used for various biological applications. However, the lipid bilayers easily delaminate and lose their natural structure after being exposed to an air-water interface. In this study, for the first time, we demonstrated that physical confinement can be used instead of chemical modifications to create air-stable membranes. Physical confinement was generated by the obstacle network induced by a peripheral enzyme, phospholipase A2. The enzyme and reacted lipids could be washed away from the obstacle network, which was detergent-resistant and strongly bonded to the solid support. On the basis of these properties, the obstacle framework on the solid support was reusable and lipid bilayers with the desired composition could be refilled and formed in the region confined by the obstacle framework. The results of fluorescence recovery after photobleaching (FRAP) indicate that the diffusivities of the lipid bilayers before drying and after rehydration were comparable, indicating the air stability of the physically confined membrane. In addition, we observed that the obstacles could trap a thin layer of water after the air-water interface passed through the lipid bilayer. Because the obstacles were demonstrated to be several times higher than a typical lipid membrane on a support, the obstacles may act as container walls, which can trap water above the lipid membrane. The water layer may have prevented the air-water interface from directly contacting the lipid membrane and, therefore, buffered the interfacial force, which could cause membrane delamination. The results suggest the possibility of using physical confinement to create air-stable membranes without changing local membrane rigidity or covering the membrane with protecting molecules.
支持的脂质双分子层平台已被用于各种生物学应用。然而，脂质双分子层在暴露于气-水界面后很容易分层并失去其自然结构。在本研究中，我们首次证明可以使用物理限制而非化学修饰来创建空气稳定的膜。物理限制是由外周酶磷脂酶A2诱导的障碍网络产生的。酶和反应后的脂质可以从抗洗涤剂且与固体支持物紧密结合的障碍网络中洗去。基于这些特性，固体支持物上的障碍框架可重复使用，并且可以在由障碍框架限定的区域中重新填充并形成具有所需组成的脂质双分子层。光漂白后荧光恢复（FRAP）的结果表明，干燥前和再水化后的脂质双分子层的扩散率相当，表明物理限制膜具有空气稳定性。此外，我们观察到在气-水界面穿过脂质双分子层后，障碍物可以捕获一层薄薄的水。由于已证明障碍物比支持物上的典型脂质膜高出几倍，因此障碍物可能起到容器壁的作用，可以在脂质膜上方捕获水。水层可能阻止了气-水界面直接接触脂质膜，因此缓冲了可能导致膜分层的界面力。结果表明，有可能在不改变局部膜刚性或用保护分子覆盖膜的情况下，使用物理限制来创建空气稳定的膜。
