ABSTRACT
The influence of the single-walled carbon nanotubes on the phospholipid bilayer has been studied using steered molecular dynamics (SMD) simulations. The impact of different nanotubes on the phospholipid bilayer structure is discussed as well as the speed of indentation. Additionally, a series of simulations with pulling out of the nanotubes from the membrane were performed. The deflection of the membrane in both nanoindenation and extraction processes is also discussed. The self-sealing ability of membrane during this process is examined. Complete degradation of the bilayer was not observed even for the most invasive nanoindentation process studied. The obtained results show that carbon nanotubes can be regarded as potential drug carriers for targeted therapy.
Subject(s)
Lipid Bilayers/chemistry , Molecular Dynamics Simulation , Nanotubes, Carbon/chemistry , Phospholipids/chemistry , Kinetics , Lipid Bilayers/metabolism , Phospholipids/metabolismABSTRACT
Computer simulation technique was used to study the dynamics of cholesterol and POPC phospholipid molecules forming a thin layer on the surface of the carbon and silicon-carbide nanotubes. Each nanotube was surrounded by an ultra-thin film formed by n lipid molecules, where n varies from 15 to 50. All studies were done for five temperatures, including physiological one (T=260, 285, 310, 335 and 360K). The influence of a nanotube on the dynamics of cholesterol or phospholipid molecules in a layer is presented and discussed. The water is ubiquitous in all biological milieus, where the cholesterol or lipids occur. Thus, simulations were performed in a water environment. Moreover, to show different behavior of lipids in systems with water the results were compared with the samples without it. The dynamical and structural observables, such as the mean square displacement, diffusion coefficient, radial distribution function, and activation energy were calculated to qualitatively investigate the behavior of cholesterol and phospholipid molecules in the layers. We observed remarkable differences between the cholesterol dynamics depending whether the ultrathin film surrounds carbon or silicon-carbide nanotube and whether the water environment appeared.
Subject(s)
Carbon Compounds, Inorganic/chemistry , Cholesterol/chemistry , Nanotubes/chemistry , Phosphatidylcholines/chemistry , Silicon Compounds/chemistry , Water/chemistry , Kinetics , Molecular Dynamics Simulation , Temperature , ThermodynamicsABSTRACT
Computer simulations have been performed to study the nanoindentation of phospholipid bilayer by the single-walled armchair carbon nanotube, filled with the nitric oxide molecules. The process has been simulated by means of molecular dynamics (MD) technique at physiological temperature T = 310 K with a constant pulling velocity of the nanotube. The force acting on the nanotube during membrane penetration has been calculated. We show that the indentation by carbon nanotube does not permanently destroy the membrane structure (self-sealing of the membrane occurs). The mobility of nitric oxide molecules during the membrane nanoindentation is discussed.
Subject(s)
Nanotubes, Carbon/chemistry , Nitric Oxide/administration & dosage , Animals , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/metabolism , Cells/drug effects , Cells/metabolism , Drug Delivery Systems , Humans , Lipid Bilayers/chemistry , Lipid Bilayers/metabolism , Models, Molecular , Molecular Dynamics Simulation , Nitric Oxide/metabolism , Phospholipids/chemistry , Phospholipids/metabolismABSTRACT
We have made the molecular dynamics (MD) simulations for the cluster of cholesterols localized near the protein farnesyltransferase (1FT2) at the physiological temperature T=309.75K. We have observed that the cholesterol molecules form a lodgment on the surface of protein. Several physical characteristics of the deposited cholesterol cluster have been calculated among those: the mean square displacement, diffusion coefficient, linear and angular velocity autocorrelation function and their Fourier transforms.
Subject(s)
Cholesterol/chemistry , Computer Simulation , Farnesyltranstransferase/chemistry , Models, Chemical , Models, Biological , Surface Properties , Temperature , Time FactorsABSTRACT
We have performed the molecular dynamics simulations for the free cholesterol cluster and the same cluster located near the carbon nanotube. We have found that the cholesterol molecules quite evenly cover the surface of single walled armchair (10, 10) carbon nanotube, forming the molecular layer. Moreover, the characteristic alignment of cholesterol molecules within the layer (along the nanotube) is observed. The comparison of the structural and dynamical observable characterizing cholesterol molecule is presented and discussed, both for the cluster with and without the presence of the nanotube.
Subject(s)
Cholesterol/chemistry , Computer Simulation , Models, Chemical , Nanotubes, Carbon/chemistry , Surface Properties , Time FactorsABSTRACT
Excessive of homocysteine in the human body is recently considered as a factor increasing the risk of the cardiovascular system diseases. The nanosystem composed of finite number of homocysteine molecules (n=20, 50 and 80) have been studied by MD technique. Several physical quantities of homocysteine nanosystem have been calculated as a function of temperature and a number of molecules in homocysteine cluster. The total dipole moment autocorrelation function and dielectric loss of the cluster have been also obtained.
