Preventing the amyloid-beta peptides accumulation on the cell membrane by applying GHz electric fields: A molecular dynamic simulation

Alzheimer's disease is associated with accumulating different amyloid peptides on the nerve cell membranes. The non-thermal effects of the GHz electric fields in this topic have yet to be well recognized. Hence, in this study, the impacts of 1 and 5 GHz electric fields on the amyloid peptide proteins accumulation on the cell membrane have been investigated, utilizing molecular dynamics (MD) simulation. The obtained results indicated that this range of electric fields did not significantly affect the peptide structure. Moreover, it was found that the peptide penetration into the membrane was increased as the field frequency was increased when the system was exposed to a 20 mv/nm oscillating electric field. In addition, it was observed that the protein-membrane interaction is reduced significantly in the presence of the 70 mv/nm electric field. The molecular level results reported in this study could be helpful in better understanding Alzheimer's disease.

Influences of electric fields on the operation of Aqy1 aquaporin channels: a molecular dynamics study

The dynamics of water molecules inside an Aquaporin channel, embedded within a stochastically fluctuating membrane, was modeled by means of the application of the molecular dynamics (MD) simulation method. We considered the effect of the existence and nonexistence of an external electric field, either constant or oscillating, on the stability of the channel. It was observed that the permeation of water molecules through the channel was increased when the channel was exposed to a constant electric field of strength -0.2 mV nm-1. Moreover, oscillating electric fields of 5 and 10 GHz frequencies, which is the range of field frequency generally present in our daily life, were applied to the channel, showing not significant effects on the stability of the channel and its important parts. In addition, we investigated the influence of the application of electric fields on the water molecule ordinations in the channels, and the results showed that the water molecule orientations were changed in response to the applied field.

Water distillation modeling by disjoint CNT-based channels under the influence of external electric fields

Using molecular dynamics method, the ion rejection and water flow inside flexible disjoint carbon-based channels were examined in the presence of electric fields. The effects of the carbon nanotube diameters and field magnitude on the nano-channel efficiency were investigated. It was observed that water flow through the filter was modified by increasing the radius of nanotubes, while the salt rejection was reduced. The particles' behaviors inside the channel were described in view of Van der Waals interactions between the water molecules, ions, and carbon atoms. Furthermore, the results indicated that the ion rejection and water flow were increased under the application of proper magnitude of electric fields. Graphical abstract Using MD simulation method, a disjoint CNT-based filter was designed to produce freshwater from a NaCl solution by the aid of external electric field. It was observed that the filter operation was significantly affected by channel structural parameters and amount of applied electric fields.

Modeling water purification by an aquaporin-inspired graphene-based nano-channel

Understanding the mechanism of water and particle transport through thin-film membranes is essential to improve the water permeability and the salt rejection rate of the purification progress. In this research, mimicking from the structure and operation of the aquaporin channel, graphene-based nano-channels were designed to be used as a water filter. The effects of variation of the channel's main elements, such as the width of the bottleneck and charges attached to the channel on its efficiency, were investigated via molecular dynamics simulations. We observe that the water flow through the channel decreases by increasing the charge, while the ion rejection rate of the channel is enhanced. Moreover, we find that the geometry and shape of the bottleneck part of the channel can affect the channel water flow and its selectivity. Finally, the pressure and the flow velocity in the channel were considered by using finite element models, and the results indicate that they are high at the entrance of the channel. The outcomes of this study can be used to improve the molecular knowledge of water desalination, which might be helpful in designing more efficient membranes. Graphical abstract As the piston pushed the solution to pass through the nano-channel, positive and negative ions are remained in the first box, by sensing electric field generated from the attached charges to the bottleneck part of the channel. Atomistic structure of channel is shown in the right part of the figure and the generated electric field is shown in the left part of the figure.

Deformation of water nano-droplets on graphene under the influence of constant and alternative electric fields

Influence of constant and oscillating electric fields on the dynamics of a water nano-droplet on graphene.

Multi scale modeling of 2450MHz electric field effects on microtubule mechanical properties

Microtubule (MT) rigidity and response to 2450MHz electric fields were investigated, via multi scale modeling approach. For this purpose, six systems were designed and simulated to consider all types of feasible interactions between α and β monomers in MT, by using all atom molecular dynamics method. Subsequently, coarse grain modeling was used to design different lengths of MT. Investigation of effects of external 2450MHz electric field on MT showed MT less rigidity in the presence of such field, which may perturb its functions. Moreover, an additional computational setup was designed to study effects of 2450MHz field on MT response to AFM tip. It was found, more tip velocity led to MT faster transformation and less time was required to change MT elastic response to plastic one, applying constant radius. Moreover it was observed smaller tip caused to increase required time to change MT elastic response to plastic one, considering constant velocity. Furthermore, exposing MT to 2450MHz field led to no significant changes in MT response to AFM tip, but quick change in MT elastic response to plastic one.

The effects of external electric fields of 900 MHz and 2450 MHz frequencies onαβ-tubulin dimer stabilized by paclitaxel: Molecular dynamics approach

Using molecular dynamics simulation method, the effects of external electric fields of 900[Formula: see text]MHz and 2450 frequencies on [Formula: see text]-tubulin dimer stabilized by paclitaxel, have been modeled. Due to this purpose, two systems, (A) [Formula: see text]-tubulin dimer and (B) [Formula: see text]-tubulin dimer stabilized by paclitaxel, were exposed to an external electric field of 0.01[Formula: see text]V/nm with frequency values of 900[Formula: see text]MHz and 2450[Formula: see text]MHz. It was found that application of these fields, which are in the range of cell phone and microwave frequencies, increased the flexibility of each system. Since paclitaxel, as chemotherapy drug, is used to increase the rigidity of dimer, application of such fields may disturb the effect of paclitaxel on the dimer. Consequently, negative side effects on the chemotherapy process may be observed.

Water molecules response to an external GHz electric field in KcsA potassium channel: A molecular modeling approach

KcsA potassium channel is a membrane protein that allows the passage of potassium ions and water molecules across the cellular membrane. Using molecular dynamics (MD) simulation method, the effect of an applied GHz oscillating electric field of strength 0.004 V/nm on the dynamics of K + and water molecules in a KcsA channel was modeled. It was found that the application of GHz range electric field caused a change in the potential energy profile of the water molecules in the filter sites, causing an increase in the delay time of the water molecules in these sites. Therefore, exposing the channel to the GHz fields can perturb the dynamics of the water molecules in the filter, and consequently, the channel operation may be disturbed. Furthermore, the results show that the applied field has no major effects on the dipole orientation of water molecules in the channel.

Modelling the influence of thermal effects induced by radio frequency electric field on the dynamics of the ATPase nano-biomolecular motors

We model the dynamics of the F(0) component of the F(0)F(1)-ATPase mitochondrion-based nano-motor operating in a stochastically-fluctuating medium that represents the intracellular environment. The stochastic dynamics are modeled via Langevin equation of motion wherein fluctuations are treated as white noise. We have investigated the influence of an applied alternating electric field on the rotary motion of the F(0) rotor in such an environment. The exposure to the field induces a temperature rise in the mitochondrion's membrane, within which the F(0) is embedded. The external field also induces an electric potential that promotes a change in the mitochondrion's transmembrane potential (TMP). Both the induced temperature and the change in TMP contribute to a change in the dynamics of the F(0). We have found that for external fields in the radio frequency (RF) range, normally present in the environment and encountered by biological systems, the contribution of the induced thermal effects, relative to that of the induced TMP, to the dynamics of the F(0) is more significant. The changes in the dynamics of the F(0) part affect the frequency of the rotary motion of the F(0)F(1)-ATPase protein motor which, in turn, affects the production rate of the ATP molecules.

Computational modeling of a rotary nanopump

The dynamics of a rotary nanopump, consisting of three coaxial carbon nanotubes and a number of graphene blades, has been simulated via application of the molecular dynamics (MD) method. In this nanopump the inner nanotube, the middle carbon nanotube with together the graphene blades and the outer nanotube are used as the shaft, rotor, and sleeve of the pump, respectively. The rotary motion of the rotor is due to the mechanical rotation of the two first carbon rings of the rotor's carbon nanotube. We found that this pump flow the gas atoms between two sides of the nanopump and it can produce an atomic gradient. Also it is observed that a rotary frequency of the rotor affected on the pump performance for generating the density gradient and the maximum performance is occurred at a special frequency of the rotor. This special rotary frequency can be computed by an analytical formula, for given material and temperatures. Moreover, the results indicate that the number of the rotor's graphene blades do not have a significant effect on the pumping capacity. Our finding provides a potentially useful mechanism for gas purification process.

Directed motion of C60 on a graphene sheet subjected to a temperature gradient

Nonequilibrium molecular dynamics simulations are used to study the motion of a C(60) molecule on a graphene sheet subjected to a temperature gradient. The C(60) molecule is actuated and moves along the system while it just randomly dances along the perpendicular direction. Increasing the temperature gradient increases the directed velocity of C(60). It is found that the free energy decreases as the C(60) molecule moves toward the cold end. The driving mechanism based on the temperature gradient suggests the construction of nanoscale graphene-based motors.

Computational modeling of an ion-driven nanomotor

The dynamics of an ion-driven rotary nanomotor, mimicking the F(0) part of the ATPase biomolecular motor, in the presence, and absence, of an external electric field have been simulated via the application of the stochastic molecular dynamics (MD) method. The rotary motion of the proposed motor arises as a result of an ion gradient established between the outer and inner parts of the environment within which the motor is embedded. We show that the operation of this motor can be controlled by such parameters as the amount of the positive ions placed in the stator part of the motor, the density of the positive ions, and the strength and frequency of the applied electric field.