EIS and PM-IRRAS studies of alamethicin ion channels in a tethered lipid bilayer

Su, Zhixun; Leitch, J. Jay; Abbasi, Fatemeh; Faragher, Robert J.; Schwan, Adrian L.; Lipkowski, Jacek

doi:10.1016/j.jelechem.2017.12.039

Cited by 29 publications

(34 citation statements)

References 46 publications

(64 reference statements)

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“…[25,28] Correspondingly, electrode-supported biomimetic membranes have been widely used, including hybrid-, tetheredand floating bilayers, to study lipid-peptide/protein interaction. [25,[29][30][31][32][33] Furthermore, useful insight has been provided in the past into the interaction of membrane-active antibiotics and compounds/toxins with supported membrane models using electroanalytical methods. [34][35][36][37][38][39][40] Alternative approaches have emerged recently, that assemble membranes supported over pores, to improve fluidity, whilst maintaining stability, without the need for tethers.…”

Section: Introductionmentioning

confidence: 99%

The Impact of Membrane Composition and Co‐Drug Synergistic Effects on Vancomycin Association with Model Membranes from Electrochemical Impedance Spectroscopy

2020

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The interaction of the antibacterial drug, vancomycin with microcavity suspended lipid bilayers (MSLB) was investigated using non‐Faradaic electrochemical impedance spectroscopy (EIS). Five MSLB compositions were prepared with increasing complexity at gold substrates: DOPC, DOPC:Chol, DOPC:SM:Chol, mammalian plasma membrane mimetic (MPM), and E. coli polar lipid extract. The latter two, are intended to mimic eukaryotic and bacterial inner membrane compositions respectively. The extent of vancomycin association and the impact drug association has on the electrochemical properties of the membrane depended on biomembrane composition. Trends were similar across all membranes but the E. coli membrane composition. Vancomycin increased membrane resistance and decreased capacitance in a saturable, concentration dependent manner, but for E. coli membrane resistance change was negligible and capacitance increased. Membrane resistance data was fit to the Langmuir‐Freundlich model to give quantitative insight into the relative extent of association of drug with membrane as a function of membrane composition. Overall, electrochemical data indicates that vancomycin associates at the interface of lipid membranes rather than penetrates the layer and this is promoted by the presence of anionic phospholipid. Interestingly, co‐incubation of the E. coli extract bilayer with both rifampicin and vancomycin, known to act synergistically, significantly promotes vancomycin association to E. coli membrane.

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Section: Introductionmentioning

confidence: 99%

The Impact of Membrane Composition and Co‐Drug Synergistic Effects on Vancomycin Association with Model Membranes from Electrochemical Impedance Spectroscopy

2020

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“…The immobilization of the membrane at the supporting substrate offers a unique opportunity to probe the properties of such an assembly with numerous surface-sensitive techniques. These include scanning probe microscopy, infrared reflective absorption spectroscopy, quartz crystal microbalance, and for conductive supports, electrochemical methods can be used as well [ 8 , 9 , 10 , 11 ]. Most popular approaches for supported lipid membrane formation involve vesicles spreading or Langmuir–Blodgett and Langmuir–Schafer techniques [ 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

2020

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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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“…Obtained spectra were fitted to the equivalent circuit, where R sol and R m represent the resistance of solution and membrane, respectively, while Q m and Q sp are constant phase elements of membrane and a thin layer of water as a spacer between the bilayer and Au (111) surface. Such a circuit is commonly used to fit the EIS spectra collected for lipid membranes immobilized on electrodes [88][89][90]. The EIS results represent the average of three independent measurements.…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 99%

Designing a Useful Lipid Raft Model Membrane for Electrochemical and Surface Analytical Studies

et al. 2021

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A model biomimetic system for the study of protein reconstitution or drug interactions should include lipid rafts in the mixed lipid monolayer, since they are usually the domains embedding membrane proteins and peptides. Four model lipid films composed of three components: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), cholesterol (Chol) and sphingomyelin (SM) mixed in different molar ratios were proposed and investigated using surface pressure measurements and thermodynamic analysis of the monolayers at the air–water interface and imaged by Brewster angle microscopy. The ternary monolayers were transferred from the air–water onto the gold electrodes to form bilayer films and were studied for the first time by electrochemical methods: alternative current voltammetry and electrochemical impedance spectroscopy and imaged by atomic force microscopy. In excess of DOPC, the ternary systems remained too liquid for the raft region to be stable, while in the excess of cholesterol the layers were too solid. The layers with SM in excess lead to the formation of Chol:SM complexes but the amount of the fluid matrix was very low. The equimolar content of the three components lead to the formation of a stable and well-organized assembly with well-developed raft microdomains of larger thickness, surrounded by the more fluid part of the bilayer. The latter is proposed as a convenient raft model membrane for further physicochemical studies of interactions with drugs or pollutants or incorporation of membrane proteins.

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EIS and PM-IRRAS studies of alamethicin ion channels in a tethered lipid bilayer

Cited by 29 publications

References 46 publications

The Impact of Membrane Composition and Co‐Drug Synergistic Effects on Vancomycin Association with Model Membranes from Electrochemical Impedance Spectroscopy

The Impact of Membrane Composition and Co‐Drug Synergistic Effects on Vancomycin Association with Model Membranes from Electrochemical Impedance Spectroscopy

Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Designing a Useful Lipid Raft Model Membrane for Electrochemical and Surface Analytical Studies

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