title: Transient potential gradients and impedance measures of tethered bilayer lipid membranes: pore-forming peptide insertion and the effect of electroporation.
abstract: In this work, we present experimental data, supported by a quantitative model, on the generation and effect of potential gradients across a tethered bilayer lipid membrane (tBLM) with, to the best of our knowledge, novel architecture. A challenge to generating potential gradients across tBLMs arises from the tethering coordination chemistry requiring an inert metal such as gold, resulting in any externally applied voltage source being capacitively coupled to the tBLM. This in turn causes any potential across the tBLM assembly to decay to zero in milliseconds to seconds, depending on the level of membrane conductance. Transient voltages applied to tBLMs by pulsed or ramped direct-current amperometry can, however, provide current-voltage (I/V) data that may be used to measure the voltage dependency of the membrane conductance. We show that potential gradients >~150 mV induce membrane defects that permit the insertion of pore-forming peptides. Further, we report here the novel (to our knowledge) use of real-time modeling of conventional low-voltage alternating-current impedance spectroscopy to identify whether the conduction arising from the insertion of a polypeptide is uniform or heterogeneous on scales of nanometers to micrometers across the membrane. The utility of this tBLM architecture and these techniques is demonstrated by characterizing the resulting conduction properties of the antimicrobial peptide PGLa.
authors.affiliation: Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, Australia. Electronic address: c.cranfield@victorchang.edu.au.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Cranfield
authors.affiliation: Surgical Diagnostics, Roseville, New South Wales, Australia.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Cornell
authors.affiliation: Karlsruhe Institute of Technology, Institute of Biological Interfaces (IBG-2), Karlsruhe, Germany.
authors.forename: Stephan L
authors.initials: SL
authors.lastname: Grage
authors.affiliation: eDAQ, Denistone East, New South Wales. Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Duckworth
authors.affiliation: Surgical Diagnostics, Roseville, New South Wales, Australia.
authors.forename: Sonia
authors.initials: S
authors.lastname: Carne
authors.affiliation: Karlsruhe Institute of Technology, Institute of Biological Interfaces (IBG-2), Karlsruhe, Germany.
authors.forename: Anne S
authors.initials: AS
authors.lastname: Ulrich
authors.affiliation: Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, Australia.
authors.forename: Boris
authors.initials: B
authors.lastname: Martinac
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D017097:Electric Impedance; D018274:Electroporation; D006046:Gold / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D010713:Phosphatidylcholines / Q000737:chemistry
chemical_list: D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; C045866:peptide-Gly-Leu-amide; D006046:Gold