title: Combined QCM-D and EIS study of supported lipid bilayer formation and interaction with pore-forming peptides.
abstract: 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.
authors.affiliation: Department of Applied Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Briand
authors.forename: Michael
authors.initials: M
authors.lastname: Zäch
authors.forename: Sofia
authors.initials: S
authors.lastname: Svedhem
authors.forename: Bengt
authors.initials: B
authors.lastname: Kasemo
authors.forename: Sarunas
authors.initials: S
authors.lastname: Petronis
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D017097:Electric Impedance; D004563:Electrochemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011791:Quartz / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D010446:Peptide Fragments; D011791:Quartz; D012822:Silicon Dioxide