The Effect of Weak Permanent Magnetic Fields on the Electric Properties of Lipid-Bilayers

1995 ◽  
Vol 50 (11-12) ◽  
pp. 833-839 ◽  
Author(s):  
Alexander Pazur
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Chlorophyll A ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Quantum Mechanical ◽  
Leakage Currents ◽  
Black Lipid Membranes ◽  
External Static Magnetic Field ◽  
Membrane Location

Abstract Black lipid membranes were prepared on a Teflon septum separating electrically the two chambers of a Teflon cuvette, using the technique of Mueller et al., (Nature 194. 979 (1962)). An external, static magnetic field was applied, whose intensity varied from 0 G to 100 G at the membrane location. Field applications higher than 10 G are effecting higher leakage currents, increased capacity and faster breakdown of the bilayer state, as compared to the absence of a magnetic field. If bilayers were doped with chlorophyll a, these effects were increased. Quantum mechanical and thermodynamical phenomena on membranes will be discussed as possible origins of these effects.

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

scholarly journals The Use of Tethered Bilayer Lipid Membranes to Identify the Mechanisms of Antimicrobial Peptide Interactions with Lipid Bilayers

Antibiotics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 12 ◽  
Author(s):  
Amani Alghalayini ◽  
Alvaro Garcia ◽  
Thomas Berry ◽  
Charles Cranfield
Keyword(s):  
New Zealand ◽  
Patch Clamp ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Antimicrobial Agents ◽  
Bilayer Lipid Membranes ◽  
Bilayer Lipid ◽  
Black Lipid Membranes ◽  
Peptide Interactions ◽  
New Research

This review identifies the ways in which tethered bilayer lipid membranes (tBLMs) can be used for the identification of the actions of antimicrobials against lipid bilayers. Much of the new research in this area has originated, or included researchers from, the southern hemisphere, Australia and New Zealand in particular. More and more, tBLMs are replacing liposome release assays, black lipid membranes and patch-clamp electrophysiological techniques because they use fewer reagents, are able to obtain results far more quickly and can provide a uniformity of responses with fewer artefacts. In this work, we describe how tBLM technology can and has been used to identify the actions of numerous antimicrobial agents.

scholarly journals Correlated diffusion in lipid bilayers

2021 ◽  
Vol 118 (48) ◽  
pp. e2113202118
Author(s):  
Rafael L. Schoch ◽  
Frank L. H. Brown ◽  
Gilad Haran
Keyword(s):  
Lipid Bilayers ◽  
Single Molecule ◽  
Lipid Membranes ◽  
Supported Lipid Bilayers ◽  
Single Molecule Tracking ◽  
Black Lipid Membranes ◽  
Molecular Tracking ◽  
Physical Materials ◽  
Multiple Molecules ◽  
Major Target

Lipid membranes are complex quasi–two-dimensional fluids, whose importance in biology and unique physical/materials properties have made them a major target for biophysical research. Recent single-molecule tracking experiments in membranes have caused some controversy, calling the venerable Saffman–Delbrück model into question and suggesting that, perhaps, current understanding of membrane hydrodynamics is imperfect. However, single-molecule tracking is not well suited to resolving the details of hydrodynamic flows; observations involving correlations between multiple molecules are superior for this purpose. Here dual-color molecular tracking with submillisecond time resolution and submicron spatial resolution is employed to reveal correlations in the Brownian motion of pairs of fluorescently labeled lipids in membranes. These correlations extend hundreds of nanometers in freely floating bilayers (black lipid membranes) but are severely suppressed in supported lipid bilayers. The measurements are consistent with hydrodynamic predictions based on an extended Saffman–Delbrück theory that explicitly accounts for the two-leaflet bilayer structure of lipid membranes.

scholarly journals Non-vesicular transfer of membrane proteins from nanoparticles to lipid bilayers

2011 ◽  
Vol 137 (2) ◽  
pp. 217-223 ◽  
Author(s):  
Sourabh Banerjee ◽  
Crina M. Nimigean
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Single Molecule ◽  
Lipid Membranes ◽  
Single Channel ◽  
Black Lipid Membranes ◽  
Potassium Channel Kcsa ◽  
Lipid Environment ◽  
Biochemical Preparation

Discoidal lipoproteins are a novel class of nanoparticles for studying membrane proteins (MPs) in a soluble, native lipid environment, using assays that have not been traditionally applied to transmembrane proteins. Here, we report the successful delivery of an ion channel from these particles, called nanoscale apolipoprotein-bound bilayers (NABBs), to a distinct, continuous lipid bilayer that will allow both ensemble assays, made possible by the soluble NABB platform, and single-molecule assays, to be performed from the same biochemical preparation. We optimized the incorporation and verified the homogeneity of NABBs containing a prototypical potassium channel, KcsA. We also evaluated the transfer of KcsA from the NABBs to lipid bilayers using single-channel electrophysiology and found that the functional properties of the channel remained intact. NABBs containing KcsA were stable, homogeneous, and able to spontaneously deliver the channel to black lipid membranes without measurably affecting the electrical properties of the bilayer. Our results are the first to demonstrate the transfer of a MP from NABBs to a different lipid bilayer without involving vesicle fusion.

Measurement of membrane tension of free standing lipid bilayers via laser-induced surface deformation spectroscopy

Soft Matter ◽  
2015 ◽  
Vol 11 (44) ◽  
pp. 8641-8647 ◽  
Author(s):  
Tomohiko Takei ◽  
Tatsuya Yaguchi ◽  
Takuya Fujii ◽  
Tomonori Nomoto ◽  
Taro Toyota ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Surface Deformation ◽  
Membrane Tension ◽  
Free Standing ◽  
Black Lipid Membranes ◽  
Non Invasive ◽  
Invasive Measurement

Non-invasive measurement of the membrane tension of free-standing black lipid membranes (BLMs), with sensitivity on the order of μN m−1, was achieved using laser-induced surface deformation (LISD) spectroscopy.

scholarly journals Magnetic Fields Induce Changes in Photosynthetic Pigments Content in Date Palm (Phoenix dactylifera L.) Seedlings

2009 ◽  
Vol 3 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Faten Dhawi ◽  
Jameel M. Al-Khayri
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Chlorophyll A ◽  
Static Magnetic Field ◽  
Photosynthetic Pigments ◽  
Date Palm ◽  
Phoenix Dactylifera ◽  
Alternating Magnetic Field ◽  
Chlorophyll B ◽  
The Impact

Growth, development and plants productivity are usually affected by photosynthetic pigments activity. Magnetic fields are known to induce biochemical changes and could be used as a stimulator for growth related reactions including affecting photosynthetic pigments. The impact of magnetic field strengths on chlorophyll and carotenoids were investigated in this study through the use of date palm (Phoenix dactylifera L.) seedlings. To study the effects of magnetic treatments on photosynthetic pigments, date palm seedlings were exposed to magnetic fields in two experiments. In the first experiment, seedlings were treated with static magnetic field at three levels of (10, 50 and 100 mT) and different durations (30, 60, 180, 240 and 360 min). At the second experiment, seedlings were treated with alternating magnetic field at 1.5 T for different durations (1, 5, 10 and 15 min). The photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids and total pigments) were assayed using spectrophotometric methods. Results indicated that pigments content (chlorophyll a, chlorophyll b, carotenoids and total pigments) was significantly increased under static magnetic field. The highest measurements were recorded at 100 mT, after 360 min of exposure. On the other hand, alternating magnetic field has decreased photosynthetic pigments content after 10 min of treatment with 1.5 T. Low magnetic field doses had a simulative effect on photosynthetic pigments whereas high doses had a negative effect. Chlorophyll a and carotenoids were more affected than chlorophyll b. Magnetic fields treatment could be used to enhance plant growth and productivity.

scholarly journals Electric Relaxation Processes in Lipid-Bilayers after Exposure to Weak Magnetic Pulses

2001 ◽  
Vol 56 (9-10) ◽  
pp. 831-837 ◽  
Author(s):  
Alexander Pazur
Keyword(s):  
Magnetic Fields ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Magnetic Particles ◽  
Biological Effects ◽  
Electrical Conductance ◽  
Relaxation Processes ◽  
Magnetic Pulse ◽  
Frequency Spectra ◽  
Weak Magnetic Fields

AbstractBiological effects of weak magnetic fields are widespread, but poorly understood. Besides magnetic particles, which have been shown to be involved in only few cases, membranes are discussed as the site of perception. However, the mechanism is unknown. We have subjected pure lipid membranes to weak magnetic pulses, and found, that their electric properties are modified.Black lipid membranes were prepared from purified asolectin on a teflon septum separating electrically the two chambers of a teflon cuvette, using the technique of Mueller et al. (1962). Single magnetic pulses were applied for 10 μs, whose intensity could be varied from 0 to 100 G (0 to 10 mT) at the membrane. Directly after the pulse decay, the conductance of the bilayers was scanned with 10 periods of a 1 kHz triangle alternating voltage (eg. a measurement time window of 10 ms). Frequency spectra of the bilayer current rose by a frequency dependent factor ≤ 2 in a broad region around 80 kHz, when the amplitude of the preceding magnetic pulse was increased from 0 to 100 G. The data show, that weak magnetic fields can significantly change the electrical conductance of lipid films. The relaxation of electrons in a two-dimensional quantum state (“quantum hollow”) will be discussed as a possible origin of these effects.

COLLAPSE/FLATTENING OF NUCLEONIC BAGS IN ULTRA-STRONG MAGNETIC FIELD

2004 ◽  
Vol 13 (06) ◽  
pp. 1157-1166 ◽  
Author(s):  
SOMA MANDAL ◽  
SOMENATH CHAKRABARTY
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Quantum Mechanical ◽  
Mechanical Instability ◽  
Strange Situation ◽  
Bag Model ◽  
Strong Magnetic Fields ◽  
Direction Transverse ◽  
Mit Bag Model

It is shown explicitly using MIT bag model that in presence of ultra-strong magnetic fields, a nucleon either flattens or collapses in the direction transverse to the external magnetic field in the classical or quantum mechanical picture respectively. Which gives rise to some kind of mechanical instability. Alternatively, it is argued that the bag model of confinement may not be applicable in this strange situation.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

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