Quantum-chemical and statistical calculations on phospholipids

Frischleder, H.; Peinel, Gustav

doi:10.1016/0009-3084(82)90049-4

Cited by 43 publications

(31 citation statements)

References 76 publications

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“…The HG dipole charges and the surrounding dipole fields preferentially orient and partially immobilize the water molecules up to a distance of 0.5 nm from the membrane surface [Frischleder and Peinel, 1982;Flewelling and Hubbell, 1986;Buuren et al, 1995;Tielemann et al, 1997]. On average, there are 10-15 water molecules, ''bound'' to one lipid HG (Fig.…”

Section: Models Membrane Propertiesmentioning

confidence: 96%

“…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].…”

Section: Models Membrane Propertiesmentioning

confidence: 98%

“…The aliphatic chains of the lipids form a hydrophobic membrane core confined by the thin hydrophilic headgroup (HG) regions [Tielemann et al, 1997]. Water in the vicinity of membranes is strongly immobilized by the dipole charges of the HGs [Frischleder and Peinel, 1982;Flewelling and Hubbell, 1986;Buuren et al, 1995]. This bound water (BW) has properties that are significantly different from that of free water and it can therefore be considered as part of the membrane [Tielemann et al, 1997].…”

Section: Introductionmentioning

confidence: 99%

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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: 96%

Section: Models Membrane Propertiesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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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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“…The model of water motions was derived from early molecular simulations of the lipid/water interface by the group of Frischleder (Frischleder and Peinel 1982). The 2 H NMR studies shed light on the mechanism of action of the water soluble polymer polyethylene glycol (PEG, MW=8,000 or higher) that was widely used for induction of cell fusion at that time.…”

Section: Introductionmentioning

confidence: 99%

Hydration of POPC bilayers studied by 1H-PFG-MAS-NOESY and neutron diffraction

et al. 2007

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The stability of lipid bilayers is ultimately linked to the hydrophobic effect and the properties of water of hydration. Magic angle spinning (MAS) nuclear Overhauser enhancement spectroscopy (NOESY) with application of pulsed magnetic field gradients (PFG) was used to study the interaction of water with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers in the fluid phase. NOESY cross-relaxation between water and polar groups of lipids, but also with methylene resonances of hydrophobic hydrocarbon chains, has been observed previously. This observation led to speculations that substantial amounts of water may reside in the hydrophobic core of bilayers. Here, the results of a quantitative analysis of cross-relaxation in a POPC/water mixture are reported. Coherences were selected via application of pulsed magnetic field gradients. This technique shortens acquisition times of NOESY spectra to 20 minutes and reduces t 1 -spectral noise, enabling detection of weak crosspeaks, like those between water and lipids, with higher precision than with non-gradient NOESY methods. The analysis showed that water molecules interact almost exclusively with sites of the lipid-water interface, including choline-, phosphate-, glycerol-, and carbonyl groups. The lifetime of lipid-water associations is rather short, on the order of 100 ps, at least one order of magnitude shorter than the lifetime of lipid-lipid associations. The distribution of water molecules over the lipid bilayer was measured at identical water content by neutron diffraction. Water molecules penetrate deep into the interfacial region of bilayers but water concentration in the hydrophobic core is below the detection limit of one water molecule per lipid, in excellent agreement with the cross-relaxation data.

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“…had to use an asymmetric distribution function [15] to understand the distortions in both parelectric dispersion and absorption -see Section 4.…”

Section: The Probesmentioning

confidence: 99%

Structure and dynamics of drug-carrier systems as studied by parelectric spectroscopy☆

Blaschke

Kankate

Kramer

2007

Advanced Drug Delivery Reviews

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In the field of topical application without or with little systemic side-effects to reach antiinflammatory or anti-androgeneous effects, nanoparticles as carriers for drugs as betamethason-17-valerate, prednicarbate, prednisolone, RU 58841-myristate or cyproterone acetate have proven to enhance the transdermal delivery. This enhancement is closely connected to the interaction of the drug molecules with the lipid carrier systems, i.e. incorporation into the carriers or attachment to their surfaces. Whereas the techniques to measure the penetration profiles in the cutaneous region of the skin are well established in the case of fluorescence microscopy applied to thin slices of epidermis or being established in the case of multiphoton microscopy to monitor this fluorescence, the methods for the investigation of the type of interaction between drugs and carrier systems are relatively new: In the case of electron spin resonance the sample volumes have to be restricted to capillary sizes to avoid parelectric losses in the microwave cavities, in the case of the novel method of parelectric spectroscopy we are free from such restrictions. The application of the latter method will be presented here in detail concerning the underlying theory, the experimental aspects as well as the algorithms to extract the parameters of interest from the measured samples. As samples we restrict ourselves to solid lipid nanoparticles coated with different surfactants as carriers for drug-, dye-or spinlabel molecules.

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Quantum-chemical and statistical calculations on phospholipids

Cited by 43 publications

References 76 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

Hydration of POPC bilayers studied by 1H-PFG-MAS-NOESY and neutron diffraction

Structure and dynamics of drug-carrier systems as studied by parelectric spectroscopy☆

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