Аннотация:Molecular dynamics simulation of a complex system comprised of a hydrated lipid membrane, nanotube "soldered" at one end and a certain molecule to be pushed through the membrane was carried out. A constant force in normal direction to the membrane is applied to a pentadecamerous polyalanine located in the channel of carbon nanotube adjoining the lipid bilayer at right angle. Under the action of the force the oligopeptide gets into the membrane. This construction can be considered as a delivery vehicle which drives the peptide to the membrane surface. As a matter of principle, tuning the nanotube (by adding functional groups) one may achieve the selectivity of the nanotube’s landing area on the cellular membrane. The pressure expulsing the peptide could arise as a result of a chemical reaction which makes the reaction mixture volume increase in the soldered nanotube. The chemical agents start the reaction under the action of a certain signal (for instance, a flash of light), and during the time in the order of a nanosecond the peptide finds oneself inside a cell. Of course, only some features can be reflected in MD calculations so far. Nonetheless, the reported simulation is a first step on the road to construction of such complicated biomimetic systems.
As a model of the microexplosive agent a set of Van der Waals spheres was taken. The spheres were growing their volumes at a certain rate. Some regimes of penetrations are considered with regard to different molecular timescales. Also the energy of absorption of the peptide onto the external surface and inside of the nanotube was calculated and proved the spontaneous self-assemblage of the nanodevice. The time of self-assembly at 300 K was estimated as 40 microseconds. Conformational stability of the delivered compound and suggestions for the choice of the explosive agent were studied as well (FIG. 2). Under the shock action the polyalanine’s alpha helix greatly changed the conformation and partially denaturated.
