Voltage jump/capacitance relaxation studies of bilayer structure and dynamics

Sargent, David F.

doi:10.1007/bf01870252

Cited by 43 publications

(15 citation statements)

References 34 publications

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“…Any of these orientations will result in a large tangential dipole moment of 18-24 D [Frischleder and Peinel, 1982]. While the HGs are relatively free to rotate, their perpendicular oscillations are of comparatively small magnitude [Sargent, 1975;Le Saux et al, 2001]. These structural features result in the anisotropy of the membrane HG layers, that is, a tangential permittivity component much higher than the normal one [Stern and Feller, 2003].…”

Section: Models Membrane Propertiesmentioning

confidence: 93%

The influence of the molecular structure of lipid membranes on the electric field distribution and energy absorption

Simeonova

Gimsa

2006

Bioelectromagnetics

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We consider the influence of the molecular structure of phospholipid membranes on their dielectric properties in the radio frequency range. Membranes have a stratified dielectric structure on the submolecular level, with the lipid chains forming a central hydrophobic layer enclosed by the polar headgroups (HGs) and bound water layers. In our numerical model, isotropic permittivities of 2.2 and 48.8 were assigned to the lipid chain and bound water layers, respectively. The HG region was assumed to possess an anisotropic static permittivity with 142.2 and 30.2 in the tangential and normal directions, respectively. The permittivities of the HG and bound water regions have been assumed to disperse at frequencies around 51 and 345 MHz to become 2.2 and 1.8, respectively, in both the normal and tangential directions. Electric field distribution and absorption were calculated for phospholipid vesicles with 75 nm radius as an example. Significant absorption has been obtained in the HG and bound water regions. Averaging the membrane absorption over the layers resulted in a decreased absorption below 1 GHz but a more than 10-fold increase above 1 GHz, compared to a model with a homogeneous membrane of averaged properties. We propose single particle dielectric spectroscopy by AC electrokinetics at low-bulk medium conductivities for an experimental verification of our model.

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Section: Models Membrane Propertiesmentioning

confidence: 93%

The influence of the molecular structure of lipid membranes on the electric field distribution and energy absorption

Simeonova

Gimsa

2006

Bioelectromagnetics

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“…So it significantly affects the conformations and collective dynamics of the neural membrane components such as phospholipids, cholesterols and proteins. Indeed, voltage-dependent ion channels perform their functions through electric field induced conformation changes of the constituent proteins (Morais-Cabral et al, 2001) and studies on the effects of electric fields on lipids support the above conclusion (Sargent, 1975;Saux et al, 2001). The spins carried by the nuclei such as 1 H, 13 C and 31 P inside the neural membranes form complex intra-and inter-molecular spin networks through various intramolecular J-and dipolar couplings and both short-and long-range intermolecular dipolar couplings.…”

Section: Introductionmentioning

confidence: 79%

Action Potential Modulation of Neural Spin Networks Suggests Possible Role of Spin

Hu¹,

Wu²

2007

Neuroquantology

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Abstract Abstract In this paper we show that nuclear spin networks in neural membranes are modulated by action potentials through J-coupling, dipolar coupling and chemical shielding tensors and perturbed by microscopically strong and fluctuating internal magnetic fields produced largely by paramagnetic oxygen. We suggest that these spin networks could be involved in brain functions since said modulation inputs information carried by the neural spike trains into them, said perturbation activates various dynamics within them and the combination of the two likely produce stochastic resonance thus synchronizing said dynamics to the neural firings. Although quantum coherence is desirable and may indeed exist, it is not required for these spin networks to serve as the subatomic components for the conventional neural networks.

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“…The pioneering work by Sargent [22] showed the usefulness of this method for the study of membrane dynamics of free standing membranes upon different modi®cation. Depending on lipid composition the BLM might be characterized by one or several relaxation times.…”

Section: Changes Of Membrane Dynamics Due To Dna Hybridizationmentioning

confidence: 99%

“…The capacitance relaxation method is based on analysis of the time course of changes in the current following sudden changes in the voltage applied across the bilayer [22]. Using this method one may obtain information about, e.g., reorientation of molecular dipoles and cluster formation.…”

Section: Capacitance Relaxationmentioning

confidence: 99%

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The Changes in Dynamics of Solid Supported Lipid Films Following Hybridization of Short Sequence DNA

et al. 2000

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The methods of conductance and capacitance relaxation were used to monitor hybridization of short sequences of DNA on the surface of lipid membranes (s-BLM) supported on thin platinum or gold layers covered by 1-dodecanethiol. The 15-mer-5H -hexadecyl-deoxythymidylic modi®ed by palmitic acid (C 16 pdT 15 ) was used as a DNA sensor that was incorporated into the BLM by the C 16 chain. The interaction of C 16 pdT 15 with s-BLM resulted in decrease membrane capacitance and conductance. The DNA hybridization on s-BLM surface resulted in an increase of s-BLM conductance, however, interaction of s-BLM modi®ed by C 16 pdT 15 with noncomplementary oligonucleotide did not change membrane conductance. The capacitance relaxation following symmetrical voltage jumps allowed us to study the dynamics of the reorientation dipole moments of the membrane. The unmodi®ed s-BLM were characterized by two relaxation components: fast t 1 20.3 AE 0.2 ms and slow t 2 590.3AE 175 ms. Modi®cation of the lipid layer by C 16 pdT 15 resulted in a decrease of amplitude of the slower component below detectable limit, while hybridization resulted in recovery of two relaxation times. Similar behavior was characterized for the free standing BLM. The changes of relaxation times might be due to the in¯uence of the hybridization process on the two-dimensional architecture of the phospholipid layer, for example on the size of the lipid clusters.

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Voltage jump/capacitance relaxation studies of bilayer structure and dynamics

Cited by 43 publications

References 34 publications

The influence of the molecular structure of lipid membranes on the electric field distribution and energy absorption

The influence of the molecular structure of lipid membranes on the electric field distribution and energy absorption

Action Potential Modulation of Neural Spin Networks Suggests Possible Role of Spin

The Changes in Dynamics of Solid Supported Lipid Films Following Hybridization of Short Sequence DNA

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