scholarly journals Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 319
Author(s):  
Joyce El-Beyrouthy ◽  
Eric Freeman
Keyword(s):  
Electric Fields ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Model Membranes ◽  
Membrane Properties ◽  
Supported Membranes ◽  
Membrane Assembly ◽  
Model Lipid Membranes ◽  
Assembly Technique ◽  
Assembly Principles

The cell membrane is a protective barrier whose configuration determines the exchange both between intracellular and extracellular regions and within the cell itself. Consequently, characterizing membrane properties and interactions is essential for advancements in topics such as limiting nanoparticle cytotoxicity. Characterization is often accomplished by recreating model membranes that approximate the structure of cellular membranes in a controlled environment, formed using self-assembly principles. The selected method for membrane creation influences the properties of the membrane assembly, including their response to electric fields used for characterizing transmembrane exchanges. When these self-assembled model membranes are combined with electrophysiology, it is possible to exploit their non-physiological mechanics to enable additional measurements of membrane interactions and phenomena. This review describes several common model membranes including liposomes, pore-spanning membranes, solid supported membranes, and emulsion-based membranes, emphasizing their varying structure due to the selected mode of production. Next, electrophysiology techniques that exploit these structures are discussed, including conductance measurements, electrowetting and electrocompression analysis, and electroimpedance spectroscopy. The focus of this review is linking each membrane assembly technique to the properties of the resulting membrane, discussing how these properties enable alternative electrophysiological approaches to measuring membrane characteristics and interactions.

ELECTROFUSION OF MODEL LIPID MEMBRANES VIEWED WITH HIGH TEMPORAL RESOLUTION

2006 ◽  
Vol 01 (04) ◽  
pp. 387-400 ◽  
Author(s):  
KARIN. A. RISKE ◽  
NATALYA BEZLYEPKINA ◽  
REINHARD LIPOWSKY ◽  
RUMIANA DIMOVA
Keyword(s):  
Electric Fields ◽  
Temporal Resolution ◽  
Lipid Membranes ◽  
Cell Biology ◽  
Digital Camera ◽  
Extensive Study ◽  
High Temporal Resolution ◽  
Giant Vesicles ◽  
Model Lipid Membranes ◽  
Millisecond Time Scale

The interaction of electric fields with lipid membranes and cells has been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest because of their widespread use in cell biology and biotechnology. Giant vesicles, being of cell size and convenient for microscopy observations, are the simplest model of the cell membrane. However, optical microscopy observation of effects caused by electric DC pulses on giant vesicles is difficult because of the short duration of the pulse. Recently this difficulty has been overcome in our lab. Using a digital camera with high temporal resolution, we were able to access vesicle fusion dynamics on a sub-millisecond time scale. In this report, we present some observations on electrodeformation and –poration of single vesicles followed by an extensive study on the electrofusion of vesicle couples. Finally, we suggest an attractive approach for creating multidomain vesicles using electrofusion and present some preliminary results on the effect of membrane stiffness on the fusion dynamics.

scholarly journals Comparison of the interactions of daunorubicin in a free form and attached to single-walled carbon nanotubes with model lipid membranes

2016 ◽  
Vol 7 ◽  
pp. 524-532 ◽  
Author(s):  
Dorota Matyszewska
Keyword(s):  
Carbon Nanotubes ◽  
Lipid Membranes ◽  
Hydrophobic Interactions ◽  
Drug Carrier ◽  
Surface Concentration ◽  
Free Drug ◽  
Model Membranes ◽  
Free Form ◽  
Comparable Amount ◽  
Model Lipid Membranes

In this work the interactions of an anticancer drug daunorubicin (DNR) with model thiolipid layers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) were investigated using Langmuir technique. The results obtained for a free drug were compared with the results recorded for DNR attached to SWCNTs as potential drug carrier. Langmuir studies of mixed DPPTE–SWCNTs-DNR monolayers showed that even at the highest investigated content of the nanotubes in the monolayer, the changes in the properties of DPPTE model membranes were not as significant as in case of the incorporation of a free drug, which resulted in a significant increase in the area per molecule and fluidization of the thiolipid layer. The presence of SWCNTs-DNR in the DPPTE monolayer at the air–water interface did not change the organization of the lipid molecules to such extent as the free drug, which may be explained by different types of interactions playing crucial role in these two types of systems. In the case of the interactions of free DNR the electrostatic attraction between positively charged drug and negatively charged DPPTE monolayer play the most important role, while in the case of SWCNTs-DNR adducts the hydrophobic interactions between nanotubes and acyl chains of the lipid seem to be prevailing. Electrochemical studies performed for supported model membranes containing the drug delivered in the two investigated forms revealed that the surface concentration of the drug-nanotube adduct in supported monolayers is comparable to the reported surface concentration of the free DNR incorporated into DPPTE monolayers on gold electrodes. Therefore, it may be concluded that the application of carbon nanotubes as potential DNR carrier allows for the incorporation of comparable amount of the drug into model membranes with simultaneous decrease in the negative changes in the membrane structure and organization, which is an important aspect in terms of side effects of the drug.

Probing Biological Samples with Near-Field Optics

2000 ◽  
Vol 6 (S2) ◽  
pp. 826-827
Author(s):  
Sarah A. Vickery ◽  
Christopher W. Hollars ◽  
Robert C. Dunn
Keyword(s):  
Optical Microscopy ◽  
Light Source ◽  
Electric Fields ◽  
Spatial Resolution ◽  
Single Molecule ◽  
Lipid Membranes ◽  
Near Field ◽  
Level Structure ◽  
Sample Surface ◽  
Model Lipid Membranes

Near-field scanning optical microscopy (NSOM) is an emerging optical technique capable of probing samples at the nanometric level. With the NSOM technique, high spatial resolution is achieved by scanning a small light source (or collector) close to a sample surface. The light source is usually formed with special fiber optic probes that funnel light down to an aperture that is smaller than the optical wavelength. By positioning the aperture close to a sample, the emerging radiation is forced to interact with the sample before diffracting out. Therefore, the spatial resolution in NSOM is only limited by the size of the aperture and its proximity to the sample, and not the wavelength of the light as in conventional optical microscopy.Recently, we have been using the single molecule detection limits combined with the unique nature of the electric fields present near the NSOM tip aperture to probe molecular level structure in model lipid membranes.

scholarly journals Proteoliposomes as energy transferring nanomaterials: enhancing the spectral range of light-harvesting proteins using lipid-linked chromophores

2019 ◽  
Author(s):  
Ashley M. Hancock ◽  
Sophie A. Meredith ◽  
Simon D. A. Connell ◽  
Lars J. C. Jeuken ◽  
Peter G. Adams
Keyword(s):  
Energy Transfer ◽  
Spectral Range ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Light Harvesting ◽  
Fluorescence Lifetime Imaging ◽  
Efficient Energy Transfer ◽  
Light Harvesting Complex ◽  
Model Lipid Membranes ◽  
Assembly Procedure

AbstractBiology provides a suite of optically-active nanomaterials in the form of “light harvesting” protein-chlorophyll complexes, however, these have drawbacks including their limited spectral range. We report the generation of model lipid membranes (proteoliposomes) incorporating the photosynthetic protein Light-Harvesting Complex II (LHCII) and lipid-tethered Texas Red (TR) chromophores that act as a “bio-hybrid” energy transferring nanomaterial. The effective spectral range of the protein is enhanced due to highly efficient energy transfer from the TR chromophores (up to 94%), producing a marked increase in LHCII fluorescence (up to 3x). Our self-assembly procedure offers excellent modularity allowing the incorporation of a range of concentrations of energy donors (TR) and acceptors (LHCII), allowing the energy transfer efficiency (ETE) and LHCII fluorescence to be tuned as desired. Fluorescence Lifetime Imaging Microscopy (FLIM) provides single-proteoliposome-level quantification of ETE, revealing distributions within the population and proving that functionality is maintained on a surface. Our membrane-based system acts as a controllable light harvesting nanomaterial with potential applications as thin films in photo-active devices.Table of Contents Figure

scholarly journals Lipid Self-Assemblies under the Atomic Force Microscope

2021 ◽  
Vol 22 (18) ◽  
pp. 10085
Author(s):  
Aritz B. García-Arribas ◽  
Félix M. Goñi ◽  
Alicia Alonso
Keyword(s):  
Lipid Membranes ◽  
Lipid Membrane ◽  
Domain Size ◽  
Model Membranes ◽  
Model Systems ◽  
Systems Model ◽  
Atomic Force ◽  
Model Lipid Membranes ◽  
The Impact

Lipid model membranes are important tools in the study of biophysical processes such as lipid self-assembly and lipid–lipid interactions in cell membranes. The use of model systems to adequate and modulate complexity helps in the understanding of many events that occur in cellular membranes, that exhibit a wide variety of components, including lipids of different subfamilies (e.g., phospholipids, sphingolipids, sterols…), in addition to proteins and sugars. The capacity of lipids to segregate by themselves into different phases at the nanoscale (nanodomains) is an intriguing feature that is yet to be fully characterized in vivo due to the proposed transient nature of these domains in living systems. Model lipid membranes, instead, have the advantage of (usually) greater phase stability, together with the possibility of fully controlling the system lipid composition. Atomic force microscopy (AFM) is a powerful tool to detect the presence of meso- and nanodomains in a lipid membrane. It also allows the direct quantification of nanomechanical resistance in each phase present. In this review, we explore the main kinds of lipid assemblies used as model membranes and describe AFM experiments on model membranes. In addition, we discuss how these assemblies have extended our knowledge of membrane biophysics over the last two decades, particularly in issues related to the variability of different model membranes and the impact of supports/cytoskeleton on lipid behavior, such as segregated domain size or bilayer leaflet uncoupling.

scholarly journals Influence of Triphenyllead Chloride on Biological and Model Membranes

2000 ◽  
Vol 55 (9-10) ◽  
pp. 764-769
Author(s):  
Halina Kleszczyńska ◽  
Krzysztof Bielecki ◽  
Janusz Sarapuk ◽  
Anna Dziamska ◽  
Stanislaw Przestalski
Keyword(s):  
Lipid Membranes ◽  
Lemna Minor ◽  
Model Membranes ◽  
Lipid Phase ◽  
Experimental Conditions ◽  
Inhibition Of Growth ◽  
Model Lipid Membranes ◽  
Osmotic Stability ◽  
Spirodela Oligorrhiza

Abstract The physiological and hemolytic toxicities of triphenyllead chloride (TPhL) as well as its modyfying influence on model lipid membranes were studied. The experiments allowed the determination of TPhL concentrations causing 50% inhibition of growth of Spirodela oligorrhiza, Lemna minor and Solvinia natans (EC50), 100% hemolysis of pig erythrocytes (C100) and destabilization of planar lipid membranes (CC). Also, fluidity of erythrocyte ghosts was measured by fluorescence technique and osmotic sensitivity of erythrocytes to the presence of TPhL. All parameters studied were found to be dependent on pH, of experimental solutions and the concentration of TPhL. Acidic conditions increased EC50, C100 and CC concentrations of TPhL. Fluorescence and osmotic measurements showed that osmotic stability and fluidity decreased with increasing trimethyllead concentration. A possible mechanism of TPhL toxicity is discussed. It is assumed that TPhL is interacting with the lipid phase of the models used. It is also assumed that there may exist various, ionic and nonionic, forms of TPhL as a result of its speciation under different experimental conditions. These species, due to their differentiated lipophilicity, may exert different effects on the model membranes studied.

Role of Hydrophobic and Hydrophilic Interactions of Organotin and Organolead Compounds with Model Lipid Membranes

1997 ◽  
Vol 52 (3-4) ◽  
pp. 209-216 ◽  
Author(s):  
Janina Gabrielska ◽  
Janusz Sarapuk ◽  
Stanisław Przestalski
Keyword(s):  
Lipid Bilayer ◽  
Organic Compounds ◽  
Lipid Membranes ◽  
Model Membranes ◽  
Model Lipid Membranes ◽  
Cationic Detergents ◽  
Mechanism Of Interaction ◽  
Organolead Compounds ◽  
Planar Membranes

AbstractThe present study was conducted to clarify the mechanism of toxicity of organic compounds using lipid model membranes (liposomes and planar lipid membranes).The compounds studied were trialkyltin and trialkyllead chlorides, dialkyltin dichlorides and some inorganic forms of those metals. Two different (anionic and cationic) detergents were also used in the experiments to change the surface properties of liposomes. As a measure of interaction between the compounds studied and model membranes were the release of liposome bound praseodymium and the change in stability of planar membranes under the influence of those compounds.On the basis of the results obtained it was postulated that the mechanism of interaction between tin-and leadorganics and model lipid membranes is a combination of different factors featuring interacting sides. The most important properties determining the behaviour of organic compounds in the interaction were lipophilicity and polarity of different parts of the organics and the steric arrangement they can take in the medium. On the other hand, the surface potential of the lipid bilayer and the environment of the lipid molecules, that play a significant role in the availability of the lipid bilayer to the organics, were important factors in the interaction.

scholarly journals Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Membranes ◽  
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.

An effect of antibiotic amphotericin B on ion transport across model lipid membranes and tonoplast membranes

2005 ◽  
Vol 70 (5) ◽  
pp. 668-675 ◽  
Author(s):  
Monika Hereć ◽  
Halina Dziubińska ◽  
Kazimierz Trębacz ◽  
Jacek W. Morzycki ◽  
Wiesław I. Gruszecki
Keyword(s):  
Ion Transport ◽  
Amphotericin B ◽  
Lipid Membranes ◽  
Model Lipid Membranes

scholarly journals Virus-Like Particles Produced Using the Brome Mosaic Virus Recombinant Capsid Protein Expressed in a Bacterial System

2021 ◽  
Vol 22 (6) ◽  
pp. 3098
Author(s):  
Aleksander Strugała ◽  
Jakub Jagielski ◽  
Karol Kamel ◽  
Grzegorz Nowaczyk ◽  
Marcin Radom ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Self Assembly ◽  
Environmental Changes ◽  
Expression System ◽  
Brome Mosaic Virus ◽  
Virus Like Particles ◽  
Assembly Principles ◽  
The Impact

Virus-like particles (VLPs), due to their nanoscale dimensions, presence of interior cavities, self-organization abilities and responsiveness to environmental changes, are of interest in the field of nanotechnology. Nevertheless, comprehensive knowledge of VLP self-assembly principles is incomplete. VLP formation is governed by two types of interactions: protein–cargo and protein–protein. These interactions can be modulated by the physicochemical properties of the surroundings. Here, we used brome mosaic virus (BMV) capsid protein produced in an E. coli expression system to study the impact of ionic strength, pH and encapsulated cargo on the assembly of VLPs and their features. We showed that empty VLP assembly strongly depends on pH whereas ionic strength of the buffer plays secondary but significant role. Comparison of VLPs containing tRNA and polystyrene sulfonic acid (PSS) revealed that the structured tRNA profoundly increases VLPs stability. We also designed and produced mutated BMV capsid proteins that formed VLPs showing altered diameters and stability compared to VLPs composed of unmodified proteins. We also observed that VLPs containing unstructured polyelectrolyte (PSS) adopt compact but not necessarily more stable structures. Thus, our methodology of VLP production allows for obtaining different VLP variants and their adjustment to the incorporated cargo.

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