Department of Applied Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden.
Analyst. 2010 Feb;135(2):343-50. doi: 10.1039/b918288h. Epub 2009 Dec 16.
A novel set-up combining the quartz crystal microbalance with dissipation monitoring technique (QCM-D) and electrochemical impedance spectroscopy (EIS) under flow conditions was successfully used to follow supported lipid bilayer (SLB) formation on SiO(2). This study demonstrates the simultaneous detection, in real time, of both the electrical and the structural properties of the SLB. The combination of the two techniques provided novel insights regarding the mechanism of SLB formation: we found indications for an annealing process of the lipid alkyl chains after the mass corresponding to complete bilayer coverage had been deposited. Moreover, the interaction of the SLB with the pore-forming toxin, gramicidin D (grD) was studied for grD concentrations ranging from 0.05 to 40 mg L(-1). Membrane properties were altered depending on the toxin concentration. For low grD concentrations, the electrical properties of the SLB changed upon insertion of active ion channels. For higher concentrations, the QCM-D data showed dramatic changes in the viscoelastic properties of the membrane while the EIS spectra did not change. AFM confirmed significant structural changes of the membrane at higher grD concentrations. Thus, the application of combined QCM-D and EIS detection provides complementary information about the system under study. This information will be particularly important for the continued detailed investigation of interactions at model membrane surfaces.
一种新型的设置，结合了石英晶体微天平与耗散监测技术（QCM-D）和电化学阻抗谱（EIS）在流动条件下，成功地用于跟踪 SiO2 上支撑脂质双层（SLB）的形成。本研究实时检测了 SLB 的电学和结构性质。两种技术的结合为 SLB 形成机制提供了新的见解：我们发现，在沉积完全双层覆盖的质量后，脂质烷基链存在退火过程的迹象。此外，还研究了 SLB 与孔形成毒素，短杆菌肽 D（grD）之间的相互作用，grD 浓度范围为 0.05 至 40mgL(-1)。根据毒素浓度，膜性质发生变化。对于低浓度的 grD，插入活性离子通道会改变 SLB 的电学性质。对于更高的浓度，QCM-D 数据显示膜的粘弹性性质发生了剧烈变化，而 EIS 谱没有变化。原子力显微镜（AFM）证实了在更高浓度的 grD 下膜的显著结构变化。因此，联合使用 QCM-D 和 EIS 检测提供了关于所研究系统的补充信息。这些信息对于继续详细研究模型膜表面的相互作用将特别重要。
