Characterization of Photophysics and Mobility of Single Molecules in a Fluid Lipid Membrane

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from Escherichia coli, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (kon) and lower dissociation (koff) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

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Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Membranes ◽

10.3390/membranes11010011 ◽

2020 ◽

Vol 11 (1) ◽

pp. 11

Author(s):

Damian Dziubak ◽

Kamil Strzelak ◽

Slawomir Sek

Keyword(s):

Electrochemical Properties ◽

Self Assembly ◽

Lipid Membranes ◽

Lipid Membrane ◽

Membrane Resistance ◽

Electrochemical Characteristics ◽

Freeze Thaw ◽

Lipid Films ◽

Supported Lipid Membranes

Supported lipid membranes are widely used platforms which serve as simplified models of cell membranes. Among numerous methods used for preparation of planar lipid films, self-assembly of bicelles appears to be promising strategy. Therefore, in this paper we have examined the mechanism of formation and the electrochemical properties of lipid films deposited onto thioglucose-modified gold electrodes from bicellar mixtures. It was found that adsorption of the bicelles occurs by replacement of interfacial water and it leads to formation of a double bilayer structure on the electrode surface. The resulting lipid assembly contains numerous defects and pinholes which affect the permeability of the membrane for ions and water. Significant improvement in morphology and electrochemical characteristics is achieved upon freeze–thaw treatment of the deposited membrane. The lipid assembly is rearranged to single bilayer configuration with locally occurring patches of the second bilayer, and the number of pinholes is substantially decreased. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced, which was manifested by the relatively high value of the membrane resistance.

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Functional characterization of PorB class II porin from Neisseria meningitidis using a tethered bilayer lipid membrane

Biosensors and Bioelectronics ◽

10.1016/j.bios.2008.07.010 ◽

2008 ◽

Vol 24 (4) ◽

pp. 831-835 ◽

Cited By ~ 22

Author(s):

Sachin R. Jadhav ◽

Yi Zheng ◽

R. Michael Garavito ◽

R. Mark Worden

Keyword(s):

Neisseria Meningitidis ◽

Lipid Membrane ◽

Functional Characterization ◽

Bilayer Lipid Membrane ◽

Class Ii ◽

Bilayer Lipid

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Characterization of Interfaces between Graphene Films and Support Substrates by Observation of Lipid Membrane Formation

The Journal of Physical Chemistry C ◽

10.1021/jp404458g ◽

2013 ◽

Vol 117 (37) ◽

pp. 18913-18918 ◽

Cited By ~ 10

Author(s):

Kenji Yamazaki ◽

Syunsuke Kunii ◽

Toshio Ogino

Keyword(s):

Lipid Membrane ◽

Membrane Formation ◽

Graphene Films

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Nanomechanical Characterization of the Synergism of Antimicrobial Peptides PGLa and Mag2 for Lipid Membrane Disruption

Biophysical Journal ◽

10.1016/j.bpj.2020.11.1318 ◽

2021 ◽

Vol 120 (3) ◽

pp. 191a

Author(s):

Fabio Perissinotto ◽

Sebastien Janel ◽

Javier Lopez-Alonso ◽

Vincent Dupres ◽

Burkhard Bechinger ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Lipid Membrane ◽

Membrane Disruption

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Detection and characterization of single molecules in aqueous solution

Applied Physics B ◽

10.1007/bf01828950 ◽

1996 ◽

Vol 63 (5) ◽

pp. 517-523 ◽

Cited By ~ 86

Author(s):

C. Zander ◽

M. Sauer ◽

K. H. Drexhage ◽

D. -S. Ko ◽

A. Schulz ◽

...

Keyword(s):

Aqueous Solution ◽

Single Molecules

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Characterization of Lipid Membrane Properties for Tunable Electroporation

ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2012-75321 ◽

2012 ◽

Author(s):

H. Jeremy Cho ◽

Shalabh C. Maroo ◽

Evelyn N. Wang

Keyword(s):

Lipid Bilayers ◽

Lipid Membrane ◽

Contact Angle Measurement ◽

Angle Measurement ◽

Membrane Properties ◽

Force Microscopy ◽

Packing Structure ◽

Atomic Force ◽

Dynamics Simulations

Lipid bilayers form nanopores on the application of an electric field. This process of electroporation can be utilized in different applications ranging from targeted drug delivery in cells to nano-gating membrane for engineering applications. However, the ease of electroporation is dependent on the surface energy of the lipid layers and thus directly related to the packing structure of the lipid molecules. 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayers were deposited on a mica substrate using the Langmuir-Blodgett (LB) technique at different packing densities and analyzed using atomic force microscopy (AFM). The wetting behavior of these monolayers was investigated by contact angle measurement and molecular dynamics simulations. It was found that an equilibrium packing density of liquid-condensed (LC) phase DPPC likely exists and that water molecules can penetrate the monolayer displacing the lipid molecules. The surface tension of the monolayer in air and water was obtained along with its breakthrough force.

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