Extreme Elongation of Vesicles Under DC Electric Fields

2008 ◽  
Author(s):  
Mohamed M. Sadik ◽  
David I. Shreiber ◽  
Jerry W. Shan ◽  
Hao Lin
Keyword(s):  
Electrical Conductivity ◽  
Electric Fields ◽  
Lipid Membranes ◽  
Deformation Behavior ◽  
Lipid Membrane ◽  
Model System ◽  
Dominant Factor ◽  
Conductivity Ratio ◽  
Pathological Changes ◽  
Dc Electric Fields

Electrodeformation refers to the deformation of cell or vesicle lipid membranes under the application of an electric field. Such a phenomenon often accompanies electroporation processes, and also can be leveraged to detect pathological changes in cells. Recent studies have suggested that the electrical conductivity difference across the lipid membrane is a dominant factor in determining the characteristics of deformation, and various regimes of deformation were observed. Using a vesicle model system, the current work is the first report of extreme elongation of vesicles of high conductivity ratio under DC electric fields. The results suggest that the osmolarity difference between the encapsulated and bathing solutions may contribute to such abnormal deformation behavior.

scholarly journals A thermodynamic scaling law for electrically perturbed lipid membranes: validation with the steepest-entropy-ascent framework

2020 ◽  
Author(s):  
I. Goswami ◽  
R. Bielitz ◽  
S.S. Verbridge ◽  
M.R. von Spakovsky
Keyword(s):  
Electric Fields ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Scaling Law ◽  
Cancer Therapeutics ◽  
Successful Implementation ◽  
Outer Cell ◽  
Scaling Model ◽  
The Impact

AbstractExperimental evidence has demonstrated the potential of transient pulses of electric fields to alter mammalian cell phenotypes. Strategies with these pulsed electric fields (PEFs) have been developed for clinical applications in cancer therapeutics, in-vivo decellularization, and tissue regeneration. Successful implementation of these strategies involves understanding how PEFs impact the cellular structures and, hence, cell behavior. The caveat, however, is that the PEF parameter space comprised of different pulse widths, amplitudes, and the number of pulses is very large, and design of experiments to explore all possible combinations of PEF parameters is prohibitive from a cost and time standpoint. In this study, a scaling law based on the Ising model is introduced to understand the impact of PEFs on the outer cell lipid membrane so that an understanding developed in one PEF pulse regime may be extended to another. Experimental study is used to argue for the scaling model. Next, the validity of this scaling model to predict the behavior of both thermally quenched and electrically perturbed lipid membranes is demonstrated via computational predictions made by the steepest-entropy-ascent quantum thermodynamic (SEAQT) framework. Based on the simulation results, a form of scaled PEF parameters is thus proposed for lipid membrane.

Amino acid and peptide hemin derivatives as new promising virucidal agents

2012 ◽  
Vol 16 (03) ◽  
pp. 297-309 ◽  
Author(s):  
Sergei A. Okorochenkov ◽  
Galina A. Zheltukhina ◽  
Vitaly A. Roginsky ◽  
Nikolai N. Nossik ◽  
Sergei L. Zheltukhin ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Membrane Permeability ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Model System ◽  
Virucidal Activity ◽  
Liposome Membrane ◽  
Simplex Virus ◽  
Membrane Components ◽  
Modes Of Interaction

We synthesized a series of hemin derivatives (HDs) substituted by residues of amino acids and peptides at either one or two propionic-acid residues, and studied the virucidal activity of the compounds obtained against herpes simplex virus. Compounds 6,7-bis-(methyl ester N0 L-seryl)-protohemin (IX) (2) and 6,7-bis-[methyl ester N0-L-arginyl)-protohemin (IX) (6) shown the highest virucidal activity. We also investigated the interaction between HDs and lipid-membrane components as a possible mechanism of virucidal action. A model system including Clark's electrode and a micellar solution of methyl linoleate was used to quantitatively assess the capability of HDs to catalyze the oxidation of polyunsaturated fatty acids as components of lipid membranes. Another model system including liposomes that consisted of dioleoylphosphatydylcholine and was loaded with the fluorescent dye carboxyfluorescein was employed to examine the effect of HDs on lipid-membrane permeability. The kinetics and efficacy of increasing liposome-membrane permeability on exposure to HDs appeared to depend on the nature of the substituents in the HDs. The findings are strongly suggestive of the presence of two different modes of interaction between an HD and the lipid membrane, i.e. oxidative and non-oxidative mechanisms possibly underlie the virucidal action of HDs.

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.

scholarly journals Interactions of Linear Analogues of Battacin with Negatively Charged Lipid Membranes

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 192
Author(s):  
Kinga Burdach ◽  
Dagmara Tymecka ◽  
Aneta Urban ◽  
Robert Lasek ◽  
Dariusz Bartosik ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Liquid Crystalline ◽  
Lipid Membrane ◽  
Attenuated Total Reflection ◽  
Gram Positive ◽  
Insertion Depth ◽  
Force Microscopy ◽  
Acyl Chains ◽  
Hydrophobic Portion ◽  
Membrane Fluidization

The increasing resistance of bacteria to available antibiotics has stimulated the search for new antimicrobial compounds with less specific mechanisms of action. These include the ability to disrupt the structure of the cell membrane, which in turn leads to its damage. In this context, amphiphilic lipopeptides belong to the class of the compounds which may fulfill this requirement. In this paper, we describe two linear analogues of battacin with modified acyl chains to tune the balance between the hydrophilic and hydrophobic portion of lipopeptides. We demonstrate that both compounds display antimicrobial activity with the lowest values of minimum inhibitory concentrations found for Gram-positive pathogens. Therefore, their mechanism of action was evaluated on a molecular level using model lipid films mimicking the membrane of Gram-positive bacteria. The surface pressure measurements revealed that both lipopeptides show ability to bind and incorporate into the lipid monolayers, resulting in decreased ordering of lipids and membrane fluidization. Atomic force microscopy (AFM) imaging demonstrated that the exposure of the model bilayers to lipopeptides leads to a transition from the ordered gel phase to disordered liquid crystalline phase. This observation was confirmed by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) results, which revealed that lipopeptide action causes a substantial increase in the average tilt angle of lipid acyl chains with respect to the surface normal to compensate for lipopeptide insertion into the membrane. Moreover, the peptide moieties in both molecules do not adopt any well-defined secondary structure upon binding with the lipid membrane. It was also observed that a small difference in the structure of a lipophilic chain, altering the balance between hydrophobic and hydrophilic portion of the molecules, results in different insertion depth of the active compounds.

Convergence effect of droplet coalescence under AC and pulsed DC electric fields

2021 ◽  
pp. 103776
Author(s):  
Xin Huang ◽  
Limin He ◽  
Xiaoming Luo ◽  
Ke Xu ◽  
Yuling Lü ◽  
...  
Keyword(s):  
Electric Fields ◽  
Droplet Coalescence ◽  
Pulsed Dc ◽  
Dc Electric Fields

Pulsed DC electric fields couple to natural NAD(P)H oscillations in HT-1080 fibrosarcoma cells

2001 ◽  
Vol 114 (8) ◽  
pp. 1515-1520 ◽  
Author(s):  
A.J. Rosenspire ◽  
A.L. Kindzelskii ◽  
H.R. Petty
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cell Function ◽  
Low Frequency ◽  
Reactive Oxygen Metabolites ◽  
Pulsed Dc ◽  
Fibrosarcoma Cells ◽  
Chemotactic Factors ◽  
Oxygen Metabolites ◽  
Dc Electric Fields

Previously, we have demonstrated that NAD(P)H levels in neutrophils and macrophages are oscillatory. We have also found that weak ultra low frequency AC or pulsed DC electric fields can resonate with, and increase the amplitude of, NAD(P)H oscillations in these cells. For these cells, increased NAD(P)H amplitudes directly signal changes in behavior in the absence of cytokines or chemotactic factors. Here, we have studied the effect of pulsed DC electric fields on HT-1080 fibrosarcoma cells. As in neutrophils and macrophages, NAD(P)H levels oscillate. We find that weak (~10(-)(5) V/m), but properly phased DC (pulsed) electric fields, resonate with NAD(P)H oscillations in polarized and migratory, but not spherical, HT-1080 cells. In this instance, electric field resonance signals an increase in HT-1080 pericellular proteolytic activity. Electric field resonance also triggers an immediate increase in the production of reactive oxygen metabolites. Under resonance conditions, we find evidence of DNA damage in HT-1080 cells in as little as 5 minutes. Thus the ability of external electric fields to effect cell function and physiology by acting on NAD(P)H oscillations is not restricted to cells of the hematopoietic lineage, but may be a universal property of many, if not all polarized and migratory eukaryotic cells.

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