Tamm L K, McConnell H M
Biophys J. 1985 Jan;47(1):105-13. doi: 10.1016/S0006-3495(85)83882-0.
Phospholipid bilayers have been formed on glass, quartz, and silicon surfaces by a sequential transfer of two monolayers at a pressure of approximately 40 dyn/cm from the air-water interface to the solid substrates. Lateral diffusion measurements of L-alpha-dipalmitoylphosphatidylcholine (DPPC) bilayers supported on oxidized silicon wafers reveal two sharp phase transitions at temperatures similar to those found in multilayer systems with several different techniques. The diffusion measurements obtained using fluorescence recovery after pattern photobleaching provide evidence for the existence of an intermediate (probably P beta' or ripple) phase in single bilayers. While in the intermediate and high temperature (liquid-crystalline L alpha) phase, the diffusion coefficients do not vary very much with temperature, a strong temperature dependence is observed in the low temperature (gel L beta') phase. This is attributed to defect-mediated diffusion. Lipids in silicon supported bilayers made from L-alpha-dioleoylphosphatidylcholine (DOPC) or L-alpha-dimyristoylphosphatidylcholine (DMPC) diffuse rapidly above their respective chain-melting transition temperatures. Arrhenius plots show straight lines with activation energies of 40.9 and 43.7 kJ/mol, respectively. Supported DPPC bilayers on oxidized silicon form long tubular liposomes when heated through their oxidized silicon form long tubular liposomes when heated through their chain-melting-phase transition, as viewed with epifluorescence microscopy. It is suggested that this is a consequence of the expansion of the lipid on the fixed solid support. Conversely, DOPC bilayers form large void areas on this substrate upon cooling. Large circular membrane defects (holes) are observed under rapid coating conditions. The formation of these defects is modulated by including small amounts of lyso-L-palmitoyl phosphatidylcholine in the DMPC-supported bilayers. A simple model describes the dependence of hole size and hole number on the concentration of lysolecithin.
通过在约40达因/厘米的压力下，将两个单层从气-水界面依次转移到固体基质上，在玻璃、石英和硅表面形成了磷脂双层。对氧化硅晶片上支撑的L-α-二棕榈酰磷脂酰胆碱（DPPC）双层进行横向扩散测量，发现在与几种不同技术的多层系统中发现的温度相似的温度下有两个明显的相变。使用图案光漂白后的荧光恢复获得的扩散测量结果为单双层中存在中间（可能是Pβ'或波纹）相提供了证据。在中间温度和高温（液晶Lα）相中，扩散系数随温度变化不大，但在低温（凝胶Lβ'）相中观察到强烈的温度依赖性。这归因于缺陷介导的扩散。由L-α-二油酰磷脂酰胆碱（DOPC）或L-α-二肉豆蔻酰磷脂酰胆碱（DMPC）制成的硅支撑双层中的脂质在各自的链熔化转变温度以上迅速扩散。阿累尼乌斯图显示为直线，活化能分别为40.9和43.7 kJ/mol。用落射荧光显微镜观察时，氧化硅上支撑的DPPC双层在通过其链熔化相变加热时形成长管状脂质体。有人认为，这是脂质在固定固体支撑物上膨胀的结果。相反，DOPC双层在冷却时在该基质上形成大的空隙区域。在快速包被条件下观察到大型圆形膜缺陷（孔）。通过在DMPC支撑的双层中加入少量溶血-L-棕榈酰磷脂酰胆碱来调节这些缺陷的形成。一个简单的模型描述了孔大小和孔数量对溶血卵磷脂浓度的依赖性。
