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

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5483
Author(s):  
Michalina Zaborowska ◽  
Damian Dziubak ◽  
Dorota Matyszewska ◽  
Slawomir Sek ◽  
Renata Bilewicz
Keyword(s):  
Membrane Proteins ◽  
Electrochemical Impedance ◽  
Ternary Systems ◽  
Model Membrane ◽  
Lipid Monolayer ◽  
Brewster Angle Microscopy ◽  
Molar Ratios ◽  
Bilayer Films ◽  
Excess Lead ◽  
Three Components

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.

scholarly journals Raft recruitment of Membrane Proteins by Native Ligands and GPI-Anchored Proteins: A Model Membrane Study

2009 ◽  
Vol 96 (3) ◽  
pp. 549a
Author(s):  
Ann Kimble-Hill ◽  
Sumit Garg ◽  
Amanda Siegel ◽  
Rainer Jordan ◽  
Christoph Naumann
Keyword(s):  
Membrane Proteins ◽  
Model Membrane

scholarly journals Fabrication of TiO2/CdS heterostructure photoanodes and optimization of light scattering to improve the photovoltaic performance of dye sensitized solar cells (DSSCs)

2021 ◽  
Author(s):  
S. Revathi ◽  
A Pricilla Jeyakumari
Keyword(s):  
Solar Cells ◽  
Conversion Efficiency ◽  
Electrochemical Impedance ◽  
Photovoltaic Performance ◽  
Dye Sensitized Solar Cells ◽  
Photocurrent Density ◽  
Cds Nanoparticles ◽  
Molar Ratios ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Abstract Currently, the TiO2/CdS photoanodes based dye sensitized solar cells (DSSCs) have shown extraordinary developments in the photo conversion efficiency. In this report, pristine TiO2, CdS and various molar ratios of TiO2/CdS photoanodes were prepared by one step microwave irradiation route and followed by doctor blade method. The sheet like morphology of the TiO2 and CdS nanoparticles were clearly evident from the SEM and TEM images. A significant reduction band gap with enhanced light absorption and rapid prevention of electron hole pair was explored by UV-DRS and PL studies. The photocurrent density-voltage (J-V) and electrochemical impedance (EIS) characteristics were analyzed for assembled solar cell. The photo-conversion efficiency of 12.8% was obtained with the configuration TiO2/CdS (200 mg) that represent a 2.5 fold increment compared to bare TiO2 (5.33%) as well as commercial Pt (6.11%). The experimental results are discussed.

scholarly journals Experimental and Theoretical Study on the Synergistic Inhibition Effect of Pyridine Derivatives and Sulfur-Containing Compounds on the Corrosion of Carbon Steel in CO2-Saturated 3.5 wt.% NaCl Solution

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3270 ◽  
Author(s):  
Junlei Tang ◽  
Yuxin Hu ◽  
Zhongzhi Han ◽  
Hu Wang ◽  
Yuanqiang Zhu ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Corrosion Inhibition ◽  
Electrochemical Impedance ◽  
Inhibition Mechanism ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Nacl Solution ◽  
Molar Ratios ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

The corrosion inhibition performance of pyridine derivatives (4-methylpyridine and its quaternary ammonium salts) and sulfur-containing compounds (thiourea and mercaptoethanol) with different molar ratios on carbon steel in CO2-saturated 3.5 wt.% NaCl solution was investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy. The synergistic corrosion inhibition mechanism of mixed inhibitors was elucidated by the theoretical calculation and simulation. The molecules of pyridine derivative compounds with a larger volume has priority to adsorb on the metal surface, while the molecules of sulfur-containing compounds with a smaller volume fill in vacancies. A dense adsorption film would be formed when 4-PQ and sulfur-containing compounds are added at a proper mole ratio.

Structure and Thermotropic Behaviour of Mixed Choline Phospholipid Model Membranes

1997 ◽  
Vol 30 (5) ◽  
pp. 776-780 ◽  
Author(s):  
G. Degovics ◽  
A. Latal ◽  
E. Prenner ◽  
M. Kriechbaum ◽  
K. Lohner
Keyword(s):  
Phase Transition ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Lipid Vesicles ◽  
Hydrocarbon Chain ◽  
Liquid Crystalline Phase ◽  
Lipid Monolayer ◽  
Repeat Distance ◽  
Molar Ratios ◽  
Gel Phase

Phosphatidylcholines and sphingomyelins are among the most abundant lipids in mammalian cell membranes, being major components of platelets or erythrocytes, and of the lipid monolayer of lipoproteins. General efforts have been devoted to the elucidation of the interaction of the ubiquitous membrane component cholesterol with these choline phospholipids, but fewer studies have been reported on the interaction between the phospholipids themselves. A gel to liquid-crystalline phase transition was observed for pure sphingomyelin liposomes at physiological temperature, while palmitoyloleoyl phosphatidylcholine adopts a liquid-crystalline phase in the temperature range 273–323 K. The two phospholipids are miscible at all molar ratios in the liquid-crystalline phase, characterized by very similar lamellar repeat distances for all binary lipid mixtures. The gel phase of pure sphingolipid liposomes exhibited a markedly smaller lamellar repeat distance as compared to mixed lipid vesicles, which increased slightly with temperature for the pure sphingomyelin (66.9–69.2 Å). Concomitantly, altered hydrocarbon chain packing was observed. Similar diffractograms were obtained in the presence of 10 mol% phosphatidylcholine. However, in the composition range between 20 and 60 mol% phosphatidylcholine in the phosphatidylcholine–sphingomyelin admixture, the lamellar repeat distance in the gel phase was markedly increased and remained almost constant (around 75 Å) below the phase transition.

scholarly journals Bacillus thuringiensis Cry1Ac toxin interaction with Manduca sexta aminopeptidase N in a model membrane environment

1998 ◽  
Vol 333 (3) ◽  
pp. 677-683 ◽  
Author(s):  
Matthew A. COOPER ◽  
Joe CARROLL ◽  
Emma R. TRAVIS ◽  
Dudley H. WILLIAMS ◽  
David J. ELLAR
Keyword(s):  
Bacillus Thuringiensis ◽  
Manduca Sexta ◽  
Model Membrane ◽  
Aminopeptidase N ◽  
Lipid Monolayer ◽  
Affinity Constant ◽  
Second Phase ◽  
High Affinity ◽  
Cry1ac Toxin ◽  
Initial Binding

The Bacillus thuringiensis Cry1Ac δ-endotoxin was shown to bind in a biphasic manner to Manduca sexta aminopeptidase N (APN) present in a novel model membrane. Surface plasmon resonance analysis allowed the quantification of toxin binding to M. sexta APN in a supported lipid monolayer. The initial binding was rapid and reversible, with an affinity constant of 110 nM. The second phase was slower and resulted in an overall affinity constant of 3.0 nM. Reagents used to disrupt protein–protein interactions did not dissociate the toxin after high-affinity binding was attained. The initial association between Cry1Ac and APN was inhibited by the sugar GalNAc, but the higher-affinity state was resistant to GalNAc-induced dissociation. The results suggest that after binding to M. sexta APN, the Cry1Ac toxin undergoes a rate-limiting step leading to a high-affinity state. A site-directed Cry1Ac mutant, N135Q, exhibited a similar initial binding affinity for APN but did not show the second slower phase. This inability to form an irreversible association with the APN-lipid monolayer helps explain the lack of toxicity of this protein towards M. sexta larvae and its deficient membrane-permeabilizing activity on M. sexta midgut brush border membrane vesicles.

scholarly journals Experimental platform for the functional investigation of membrane proteins in giant unilamellar vesicles

2021 ◽  
Author(s):  
Nicolas Dolder ◽  
Philipp Mueller ◽  
Christoph von Ballmoos
Keyword(s):  
Membrane Proteins ◽  
Model Membrane ◽  
Giant Unilamellar Vesicles ◽  
Cellular Functions ◽  
Unilamellar Vesicles ◽  
Synthetic Cells ◽  
Buffer Composition ◽  
Protein Incorporation ◽  
Functional Investigation

Giant unilamellar vesicles (GUVs) are micrometer-sized model membrane systems that can be viewed directly under the microscope. They serve as scaffolds for the bottom-up creation of synthetic cells, targeted drug delivery and have been used in many in vitro studies of membrane related phenomena. GUVs are also of interest for the functional investigation of membrane proteins that carry out many key cellular functions. A major hurdle to a wider application of GUVs in this field is the diversity of existing protocols that are optimized for individual proteins. Here, we compare PVA assisted and electroformation techniques for GUV formation under physiologically relevant conditions, and analyze the effect of immobilization on vesicle structure and membrane tightness towards small substrates and protons. There, differences in terms of yield, size, and leakage of GUVs produced by PVA assisted swelling and electroformation were found, dependent on salt and buffer composition. Using fusion of oppositely charged membranes to reconstitute a model membrane protein, we find that empty vesicles and proteoliposomes show similar fusion behavior, which allows for a rapid estimation of protein incorporation using fluorescent lipids.

scholarly journals Surface Chemistry Study of the Interactions of Sesame Oil with Meibomian Films

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 464
Author(s):  
Petar Eftimov ◽  
Norihiko Yokoi ◽  
Georgi As. Georgiev
Keyword(s):  
Meibomian Gland ◽  
Sesame Oil ◽  
Brewster Angle Microscopy ◽  
Monounsaturated Fat ◽  
Fixed Amount ◽  
Molar Ratios ◽  
Meibomian Gland Secretion ◽  
Acyl Chains ◽  
Nonpolar Lipids ◽  
Phosphate Buffered Saline

A possible approach for the treatment of meibomian gland disease (MGD) can be the supplementation of meibomian gland secretion (MGS) with nonpolar lipids (NPL) rich plant oils. Sesame oil (SO), approximately equal in monounsaturated fat (oleic acid, 40% of total) and polyunsaturated fat (linoleic acid, 42% of total), has shown multiple health benefits due to its anti-inflammatory and antioxidant effects. Thus, the interactions between SO and MGS in surface layers deserve further study. Therefore, pseudobinary films were formed with controlled MGS/SO molar ratios (0%, 10%, 30%, 50%, and 100% SO) at the air/water surface of the Langmuir trough over phosphate buffered saline (pH 7.4) subphase. Surface pressure (π)-area (A) isotherms and Brewster angle microscopy observations showed nonideal interactions where SO aggregates with MGS and complements the NPL stratum of the meibomian layers. The analysis of stress relaxation transients with Kohlrausch–Williams–Watts equation revealed that the supplementation of fixed amount of MGS with excess lipids via SO altered the dilatational elasticity of the films as reflected by the increase of the exponent β. Thus, SO with its unique combination of high oxidative stability and abundance of long polyunsaturated acyl chains might be a useful supplement to MGS layers.

scholarly journals Experimental and theoretical study on the synergistic inhibition effect of yridine derivatives and sulfur-containing compounds on the corrosion of carbon steel in CO2-saturated 3.5 wt.% NaCl solution

2018 ◽  
Author(s):  
Junlei Tang ◽  
Yuxin Hu ◽  
Zhongzhi Han ◽  
Hu Wang ◽  
Yuanqiang Zhu ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Corrosion Inhibition ◽  
Electrochemical Impedance ◽  
Inhibition Mechanism ◽  
Pyridine Derivatives ◽  
Nacl Solution ◽  
Molar Ratios ◽  
Inhibition Performance ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

The corrosion inhibition performance of pyridine derivatives (4-methylpyridine and its quaternary ammonium salts) and sulfur-containing compounds (thiourea and mercaptoethanol) with different molar ratios on carbon steel in CO2-saturated 3.5 wt.% NaCl solution was investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The synergistic corrosion inhibition mechanism of mixed inhibitors was elucidated by the theoretical calculation and simulation. The molecule of pyridine derivatives compound with larger volume has the priority to adsorb on the metal surface, while the molecules of sulfur-containing compounds with smaller volume fill in vacancies. A dense adsorption film would be formed when 4-PQ and sulfur-containing compounds are added at a proper mole ratio.

scholarly journals Electrochemical Behavior of Metamitron Herbicide at the Interface of Two Immiscible Electrolyte Solutions

2017 ◽  
Vol 58 (3) ◽  
Author(s):  
Alma Gricel Reyes-Reyes ◽  
Judith Amador-Hernández ◽  
Miguel Velázquez-Manzanares
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Electrolyte Solutions ◽  
Lipid Monolayer ◽  
Equilibrium Partition ◽  
Ph Dependent

<p>The electrochemical behavior of the metamitron herbicide at the water|1,2-dichloroethane interface was studied by means of cyclic voltammetry and Electrochemical Impedance Spectroscopy. The results show that metamitron extraction across the interface was pH dependent. The curves capacitance-potential shown that the presence of a lipid monolayer inhibits the metamitrone transport across the interface. In this paper the equilibrium partition of metamitron across the interface of two immiscible electrolyte solutions is discussed.</p>

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