Combined QCM-D and EIS study of supported lipid bilayer formation and interaction with pore-forming peptides

摘要

A novel set-up combining the quartz crystal microbalance with dissipation monitoring techniquen(QCM-D) and electrochemical impedance spectroscopy (EIS) under flow conditions was successfullynused to follow supported lipid bilayer (SLB) formation on SiO2. This study demonstrates thensimultaneous detection, in real time, of both the electrical and the structural properties of the SLB. Thencombination of the two techniques provided novel insights regarding the mechanism of SLB formation:nwe found indications for an annealing process of the lipid alkyl chains after the mass corresponding toncomplete bilayer coverage had been deposited. Moreover, the interaction of the SLB with the poreformingntoxin, gramicidin D (grD) was studied for grD concentrations ranging from 0.05 to 40 mg Lu00021.nMembrane properties were altered depending on the toxin concentration. For low grD concentrations,nthe electrical properties of the SLB changed upon insertion of active ion channels. For highernconcentrations, the QCM-D data showed dramatic changes in the viscoelastic properties of thenmembrane while the EIS spectra did not change. AFM confirmed significant structural changes of thenmembrane at higher grD concentrations. Thus, the application of combined QCM-D and EIS detectionnprovides complementary information about the system under study. This information will benparticularly important for the continued detailed investigation of interactions at model membranensurfaces.