Study on Molecular Thermal Energy Transfer in a Lipid Bilayer

2007 ◽  
Author(s):  
Takeo Nakano ◽  
Taku Ohara ◽  
Gota Kikugawa
Keyword(s):  
Energy Transfer ◽  
Thermal Resistance ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Thermal Energy ◽  
Hydrocarbon Chain ◽  
Bilayer Membrane ◽  
Head Group ◽  
Total Thermal Resistance ◽  
Dynamics Simulations

In recent studies, lipid bilayers attract a great deal of interest as a material for nanoscale structure. Some devices utilizing lipid bilayers, which include various kinds of sensors and molecular sorting devices, have been proposed. Understanding of thermal energy transfer in the lipid bilayers plays an important role in developing such devices with nano structures. In this study, we have investigated the energy transfer along and across the bilayer membrane by molecular dynamics simulations of the lipid bilayer in liquid water. We found that along the bilayer, the thermal energy is transferred by the interaction principally between water molecules and barely between lipid molecules. On the other hand, in the latter case, total thermal resistance of the lipid bilayer structure is composed of the thermal resistance of the structure’s various parts, including water, head group of lipid, and tail hydrocarbon chain of lipid, which show different values. It is found that the tail hydrocarbon chains have the highest thermal resistance.

Molecular Heat Transfer in Lipid Bilayers With Symmetric and Asymmetric Tail Chains

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Takeo Nakano ◽  
Gota Kikugawa ◽  
Taku Ohara
Keyword(s):  
Energy Transfer ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Lipid Bilayers ◽  
Thermal Energy ◽  
Phosphatidyl Choline ◽  
Soft Matter ◽  
Intramolecular Energy Transfer ◽  
Alkyl Chains ◽  
Polymer Molecules

Intramolecular energy transfer in polymer molecules plays a dominant role in heat conduction in polymer materials. In soft matter where polymer molecules form an ordered structure, the intramolecular energy transfer works in an anisotropic manner, which results in an anisotropic thermal conductivity. Based on this idea, thermal energy transfer in lipid bilayers, a typical example of soft matter, has been analyzed in the present study. Nonequilibrium molecular dynamics simulations were carried out on single component lipid bilayers with ambient water. In the simulations, dipalmitoyl-phosphatidyl-choline (DPPC), dilauroyl-phosphatidyl-choline (DLPC), and stearoyl-myristoyl-phosphatidyl-choline (SMPC), which have two alkyl chains with 16 C atoms for each, 12 C atoms for each, and 18 and 14 C atoms, respectively, were used as lipid molecules. The thermal energy transfer has been decomposed to inter- and intramolecular energy transfer between individual molecules or molecular sites, and its characteristics were discussed. In the case of heat conduction in the direction across the membranes (cross-plane heat conduction), the highest thermal resistance exists at the center of the lipid bilayer, where lipid alkyl chains face each other. The asymmetric chain length of SMPC reduces this thermal resistance at the interface between lipid monolayers. The cross-plane thermal conductivities of lipid monolayers are 4.8–6.5 times as high as the ones in the direction parallel to the membranes (in-plane) for the cases of the tested lipids. The overall cross-plane thermal conductivities of the lipid bilayers are reduced to be approximately half of those of the monolayers, due to the thermal resistance at the interfaces between two monolayers. The lipid bilayer of SMPC with tail chains of asymmetric length exhibits the highest cross-plane thermal conductivity. These results provide detailed information about the transport characteristics of thermal energy in soft matter, which are new materials with design flexibility and biocompatibility. The results lead to their design to realize desired thermophysical properties and functions.

scholarly journals Molecular dynamics simulations and experimental studies reveal differential permeability of withaferin-A and withanone across the model cell membrane

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Renu Wadhwa ◽  
Neetu Singh Yadav ◽  
Shashank P. Katiyar ◽  
Tomoko Yaguchi ◽  
Chohee Lee ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Cell Membrane ◽  
Molecular Dynamics Simulations ◽  
Experimental Studies ◽  
Bilayer Membrane ◽  
Withaferin A ◽  
Head Group ◽  
Polar Head Group ◽  
Natural Drugs ◽  
Dynamics Simulations

AbstractPoor bioavailability due to the inability to cross the cell membrane is one of the major reasons for the failure of a drug in clinical trials. We have used molecular dynamics simulations to predict the membrane permeability of natural drugs—withanolides (withaferin-A and withanone) that have similar structures but remarkably differ in their cytotoxicity. We found that whereas withaferin-A, could proficiently transverse through the model membrane, withanone showed weak permeability. The free energy profiles for the interaction of withanolides with the model bilayer membrane revealed that whereas the polar head group of the membrane caused high resistance for the passage of withanone, the interior of the membrane behaves similarly for both withanolides. The solvation analysis further revealed that the high solvation of terminal O5 oxygen of withaferin-A was the major driving force for its high permeability; it interacted with the phosphate group of the membrane that led to its smooth passage across the bilayer. The computational predictions were tested by raising and recruiting unique antibodies that react to withaferin-A and withanone. The time-lapsed analyses of control and treated cells demonstrated higher permeation of withaferin-A as compared to withanone. The concurrence between the computation and experimental results thus re-emphasised the use of computational methods for predicting permeability and hence bioavailability of natural drug compounds in the drug development process.

scholarly journals Asymmetric phospholipids impart novel biophysical properties to lipid bilayers allowing environmental adaptation

2020 ◽  
Author(s):  
Paul Smith ◽  
Dylan M. Owen ◽  
Christian D. Lorenz ◽  
Maria Makarova
Keyword(s):  
Lipid Bilayers ◽  
Mammalian Cells ◽  
Yeast Species ◽  
Membrane Lipid ◽  
Head Group ◽  
Biophysical Properties ◽  
Biophysical Parameters ◽  
Unsaturated Lipids ◽  
Chain Acyl ◽  
Dynamics Simulations

AbstractPhospholipids are a diverse group of biomolecules consisting of a hydrophilic head group and two hydrophobic acyl tails. The nature of the head and length and saturation of the acyl tails are important for defining the biophysical properties of lipid bilayers. It has recently been shown that the membranes of certain yeast species contain high levels of unusual asymmetric phospholipids, consisting of one long and one medium chain acyl moiety – a configuration not common in mammalian cells or other well studied model yeast species. This raises the possibility that structurally asymmetric phospholipids impart novel biophysical properties to the yeast membranes. Here, we use atomistic molecular dynamics simulations (MD) and environmentally-sensitive fluorescent membrane probes to characterize key biophysical parameters of membranes formed from asymmetric lipids for the first time. Interestingly, we show that saturated, but asymmetric phospholipids maintain membrane lipid order across a wider range of temperatures and do not require acyl tail unsaturation or sterols to maintain their properties. This may allow cells to maintain membrane fluidity even in environments which lack the oxygen required for the synthesis of unsaturated lipids and sterols.

Molecular Dynamics Study on Thermal Resistance Between Amorphous Silica Nanoparticles

2017 ◽  
Author(s):  
Fanhe Meng ◽  
Jin Liu ◽  
Robert F. Richards
Keyword(s):  
Molecular Dynamics ◽  
Thermal Resistance ◽  
Silica Nanoparticles ◽  
Amorphous Silica ◽  
Thermal Transport ◽  
Numerical Results ◽  
Dynamics Simulation ◽  
Total Thermal Resistance ◽  
Constriction Resistance ◽  
Dynamics Simulations

Nanoparticle-based materials have demonstrated extremely low thermal conductivities, a property that has made them attractive candidates in a variety of macroscale and microscale applications. Understanding the thermal transport between nanoparticles is necessary for the further development of these materials. Molecular dynamics simulation is an effective method to investigate thermal transport on these scales because no assumption about phonon transmission at the nanoparticle interface, nor prior knowledge of thermal transport of the system is necessary. In this work, the total thermal resistance between adjacent amorphous silica nanoparticles is calculated using non-equilibrium molecular dynamics simulations (NEMD). Numerical results show that interparticle resistance depends strongly on the forces between particles, in particular the presence or absence of chemical bonds between nanoparticles. In addition, the effect of interfacial force strength on thermal resistance increases as nanoparticle diameter decreases. Numerical results are compared to interparticle resistances determined from the predictions of the analytical constriction resistance model. The simulation results are shown to be in good agreement the constriction resistance theory depending on the choice of surface energy.

scholarly journals Interaction of metalloporphyrins with lipid bilayers, a calorimetric study

2011 ◽  
Vol 34 (1) ◽  
pp. 11-14
Author(s):  
Katarzyna Pamin ◽  
Jan Połtowicz ◽  
Joanna Kiełkowicz ◽  
Andrzej Hendrich
Keyword(s):  
Experimental Data ◽  
Phase Transitions ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Electrostatic Interactions ◽  
Acyl Chain ◽  
Head Group ◽  
Calorimetric Study ◽  
Polar Head Group ◽  
Polar Head

Interaction of metalloporphyrins with lipid bilayers, a calorimetric studyThe interaction of three metalloporphyrins, containing manganese, iron and cobalt atoms, with lipid bilayers composed of neutral (DPPC) or charged (DMPG) phospholipids were studied by means of scanning differential calorimetry. We found only minute effects exerted by studied compounds on DPPC, while phase transitions of charged DMPG were seriously affected by porphyrins. Analysis of experimental data revealed that due to the electrostatic interactions DMPG bilayers are perturbed not only in the polar head group region. Putative rearrangements of the polar heads packing affects also the acyl chain region of this lipid bilayer. Perturbation of DMPG polar heads induced by porphyrin in complex with manganese atoms is bigger than that induced by other porphyrins.

Quantitative assessment of the thermal stored energy in protective clothing under low-level radiant heat exposure

2017 ◽  
Vol 88 (24) ◽  
pp. 2867-2879 ◽  
Author(s):  
He Jiazhen ◽  
Chen Yan ◽  
Wang Lichuan ◽  
Li Jun
Keyword(s):  
Energy Storage ◽  
Thermal Resistance ◽  
Thermal Energy ◽  
Protective Clothing ◽  
Heat Exposure ◽  
Radiant Heat ◽  
Air Gap ◽  
Heat Fluxes ◽  
Total Thermal Resistance ◽  
Fabric System

In addition to direct thermal energy from a heating source, a large amount of thermal energy stored in clothing will continuously discharge to the skin after exposure. Therefore, thermal protective clothing may have a dual effect on human skin in reality. An experimental investigation was conducted to study the energy storage within 15 different combinations of clothing layers exposed to low heat fluxes ranging from 2.5 kW/m2 to 8.5 kW/m2. The energy storage process, the distribution of energy storage, and variables critically impacting energy storage, including fabric layers, air gap under clothing, thermal resistance and heat source intensity were discussed. It is demonstrated that the weight and thickness of the fabric are dominating factors affecting energy storage. For a multilayer fabric system, 36–57% of the total amount of energy is stored in the outer shell. The neighboring layer proves to be very important for the energy storage in an individual fabric. The air gap that exists between the fabric and the skin exerts an influence on the energy storage within fabric layers. In addition, a linear correlation is observed between the energy storage and the total thermal resistance of a fabric system. The research findings will be brought to researchers to better understand the mechanism and factors associated with energy storage and help develop new fabric combinations in order to minimize heat transmission to the skin.

Effect of Alkyl Chain Length on Molecular Heat Transfer Characteristics in Lipid Bilayers

2011 ◽  
Author(s):  
Takeo Nakano ◽  
Gota Kikugawa ◽  
Taku Ohara
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Lipid Bilayers ◽  
Chain Length ◽  
Phosphatidyl Choline ◽  
Acyl Chain ◽  
Nonequilibrium Molecular Dynamics ◽  
Acyl Chain Length ◽  
Acyl Chains ◽  
Dynamics Simulations

Nonequilibrium molecular dynamics simulations are carried out on single component lipid bilayers with ambient water in order to investigate the effect of acyl chain length on heat transport characteristics along and across the membranes. In this study, dipalmitoyl-phosphatidyl-choline (DPPC), dilauroyl-phosphatidyl-choline (DLPC), and stearoyl-myristoyl-phosphatidyl-choline (SMPC) which has two acyl chains of both sixteen C atoms, both twelve C atoms, and eighteen and fourteen C atoms, respectively, were used as lipid molecules. In the direction along the membranes, thermal conductivity corresponds with that of each membrane. On the other hand, in the direction across membrane, the highest thermal resistance exists at the center of lipid bilayer where lipid acyl chains face each other. However, asymmetric chain length reduces thermal resistance at the interface between lipid monolayers. Therefore, thermal conductivity across the membrane which consists of asymmetric chain length is higher than those which consist of symmetric chain length.

scholarly journals Terminal lipophilization of a unique DNA dodecamer by various nucleolipid headgroups: Their incorporation into artificial lipid bilayers and hydrodynamic properties

2015 ◽  
Vol 11 ◽  
pp. 913-929 ◽  
Author(s):  
Emma Werz ◽  
Helmut Rosemeyer
Keyword(s):  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Single Molecule ◽  
Head Group ◽  
Artificial Lipid Bilayers ◽  
Decisive Importance ◽  
Head Groups ◽  
Single Molecule Fluorescence Spectroscopy ◽  
Dna Dodecamer ◽  
And Diffusion

A series of six cyanine-5-labeled oligonucleotides (LONs 10–15), each terminally lipophilized with different nucleolipid head groups, were synthesized using the recently prepared phosphoramidites 4b–9b. The insertion of the LONs within an artificial lipid bilayer, composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), was studied by single molecule fluorescence spectroscopy and microscopy with the help of an optically transparent microfluidic sample carrier with perfusion capabilities. The incorporation of the lipo-oligonucleotides into the bilayer was studied with respect to efficiency (maximal bilayer brightness) as well as stability against perfusion (final stable bilayer brightness). Attempts to correlate these parameters with the log P values of the corresponding nucleolipid head groups failed, a result which clearly demonstrates that not only the lipophilicity but mainly the chemical structure and topology of the head group is of decisive importance for the optimal interaction of a lipo-oligonucleotide with an artificial lipid bilayer. Moreover, fluorescence half-live and diffusion time values were measured to determine the diffusion coefficients of the lipo-oligonucleotides.

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