scholarly journals Flip-flop asymmetry of cholesterol in model membranes induced by thermal gradients

Soft Matter ◽  
2020 ◽  
Vol 16 (25) ◽  
pp. 5925-5932
Author(s):  
James W. Carter ◽  
Miguel A. Gonzalez ◽  
Nicholas J. Brooks ◽  
John M. Seddon ◽  
Fernando Bresme
Keyword(s):  
Lipid Membranes ◽  
Model Membranes ◽  
Thermal Gradients ◽  
Flip Flop

Thermal gradients induce flip-flop asymmetry of cholesterol in lipid membranes.

scholarly journals Electrodes modified with lipid membranes to study quinone oxidoreductases

2009 ◽  
Vol 37 (4) ◽  
pp. 707-712 ◽  
Author(s):  
Sophie A. Weiss ◽  
Lars J.C. Jeuken
Keyword(s):  
Lipid Membranes ◽  
Biochemical Properties ◽  
Model Membranes ◽  
Water Soluble ◽  
Enzyme Assays ◽  
Membrane Enzymes ◽  
Membrane Bound ◽  
Hydrophobic Nature

Quinone oxidoreductases are a class of membrane enzymes that catalyse the oxidation or reduction of membrane-bound quinols/quinones. The conversion of quinone/quinol by these enzymes is difficult to study because of the hydrophobic nature of the enzymes and their substrates. We describe some biochemical properties of quinones and quinone oxidoreductases and then look in more detail at two model membranes that can be used to study quinone oxidoreductases in a native-like membrane environment with their native lipophilic quinone substrates. The results obtained with these model membranes are compared with classical enzyme assays that use water-soluble quinone analogues.

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.

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.

Flip-Flop of Doxorubicin across Erythrocyte and Lipid Membranes

1997 ◽  
Vol 54 (10) ◽  
pp. 1151-1158 ◽  
Author(s):  
Ronit Regev ◽  
Gera D Eytan
Keyword(s):  
Lipid Membranes ◽  
Flip Flop

Influence of Counterions on the Interaction of Pyridinium Salts with Model Membranes

1999 ◽  
Vol 54 (11) ◽  
pp. 952-955 ◽  
Author(s):  
Janusz Sarapuk ◽  
Halina Kleszczyńska ◽  
Juliusz Pernak ◽  
Joanna Kalewska ◽  
Bożenna Różycka-Roszak
Keyword(s):  
Lipid Membranes ◽  
Hydration Shell ◽  
Water Structure ◽  
Model Membranes ◽  
Pyridinium Salts ◽  
High Concentration ◽  
Hydrated Ions ◽  
Destructive Action ◽  
Planar Lipid Membranes ◽  
First Hydration Shell

Abstract The interaction of pyridinium salts (PS) with red blood cells and planar lipid membranes was studied. The aim of the work was to find whether certain cationic surfactant counterion influence its possible biological activity. The counterions studied were Cl- , Br-, I-, ClO4-, BF4- and NO3-. The model membranes used were erythrocyte and planar lipid membranes (BLM). At high concentration the salts caused 100% erythrocyte hemolysis (C 100) or broke BLMs (CC). Both parameters describe mechanical properties of model membranes. It was found that the efficiency of the surfactant to destabilize model membranes depended to some degree on its counterion. In both, erythrocyte and BLM experiments, the highest efficiency was observed for Br-, the lowest for NO3-. The influence of all other anions on surfactant efficiency changed between these two extremities; that of chloride and perchlorate ions was similar. Some differences were found in the case o f BF4- ion. Its influence on hemolytic possibilities of PS was significant while BLM destruction required relatively high concentration of this anion. Apparently, the influence of various anions on the destructive action of PS on the model membrane used may be attributed to different mobilities and radii of hydrated ions and hence, to different possibilities of particular anions to modify the surface potential of model membranes. This can lead to a differentiated interaction of PS with modi­fied bilayers. Moreover, the effect of anions on the water structure must be taken into ac­count. It is important whether the anions can be classified as water ordering kosmotropes that hold the first hydration shell tightly or water disordering chaotropes that hold water molecules in that shell loosely.

Structure and physical properties of biomembranes and model membranes

2006 ◽  
Vol 56 (6) ◽  
Author(s):  
T. Hianik
Keyword(s):  
Physical Properties ◽  
Lipid Membranes ◽  
Complex Structure ◽  
Ionic Channels ◽  
Model Membranes ◽  
Model Systems ◽  
Bilayer Lipid Membranes ◽  
Lipid Monolayers ◽  
Physical Point ◽  
Bilayer Lipid

Structure and physical properties of biomembranes and model membranesBiomembranes belong to the most important structures of the cell and the cell organels. They play not only structural role of the barrier separating the external and internal part of the membrane but contain also various functional molecules, like receptors, ionic channels, carriers and enzymes. The cell membrane also preserves non-equillibrium state in a cell which is crucial for maintaining its excitability and other signaling functions. The growing interest to the biomembranes is also due to their unique physical properties. From physical point of view the biomembranes, that are composed of lipid bilayer into which are incorporated integral proteins and on their surface are anchored peripheral proteins and polysaccharides, represent liquid scrystal of smectic type. The biomembranes are characterized by anisotropy of structural and physical properties. The complex structure of biomembranes makes the study of their physical properties rather difficult. Therefore several model systems that mimic the structure of biomembranes were developed. Among them the lipid monolayers at an air-water interphase, bilayer lipid membranes (BLM), supported bilayer lipid membranes (sBLM) and liposomes are most known. This work is focused on the introduction into the "physical word" of the biomembranes and their models. After introduction to the membrane structure and the history of its establishment, the physical properties of the biomembranes and their models areare stepwise presented. The most focus is on the properties of lipid monolayers, BLM, sBLM and liposomes that were most detailed studied. This contribution has tutorial character that may be usefull for undergraduate and graduate students in the area of biophysics, biochemistry, molecular biology and bioengineering, however it contains also original work of the author and his co-worker and PhD students, that may be usefull also for specialists working in the field of biomembranes and model membranes.

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