Effect of Peierls transition in armchair carbon nanotube on dynamical behaviour of encapsulated fullerene.

The changes of dynamical behaviour of a single fullerene molecule inside an armchair carbon nanotube caused by the structural Peierls transition in the nanotube are considered. The structures of the smallest C20 and Fe@C20 fullerenes are computed using the spin-polarized density functional theory. Significant changes of the barriers for motion along the nanotube axis and rotation of these fullerenes inside the (8,8) nanotube are found at the Peierls transition. It is shown that the coefficients of translational and rotational diffusions of these fullerenes inside the nanotube change by several orders of magnitude. The possibility of inverse orientational melting, i.e. with a decrease of temperature, for the systems under consideration is predicted.

The role of molecular clusters in the filling of carbon nanotubes.

We have demonstrated that the ability of fullerenes to form clusters is essential for the filling of single-walled carbon nanotubes in solution. In solutions where C60 exists in the form of discrete solvated molecules (e.g., in CS2) no fullerene encapsulation in nanotubes takes place, as the large molar excess of solvent compared to solute prohibits C60 from entering the nanotubes. However, in solutions containing large clusters of C60 (e.g., in n-hexane) nanotubes become densely filled with fullerene molecules despite the large excess of solvent. The interactions between carbon nanotubes and fullerene clusters provide an efficient transport of C60 into nanotubes that avoids the detrimental effects of the solvent molecules. This new mechanism provides the first rational explanation of experiments involving nanotube filling with guest-molecules in solution.

Biocompatibility and applications of carbon nanotubes in medical nanorobots.

The set of nanoelectromechanical systems (NEMS) based on relative motion of carbon nanotubes walls is proposed for use in medical nanorobots. This set includes electromechanical nanothermometer, jet nanoengine, nanosyringe (the last can be used simultaneously as nanoprobe for individual biological molecules and drug nanodeliver). Principal schemes of these NEMS are considered. Operational characteristics of nanothermometer are analyzed. The possible methods of these NEMS actuation are considered. The present-day progress in nanotechnology techniques which are necessary for assembling of NEMS under consideration is discussed. Biocompatibility of carbon nanotubes is analyzed in connection with perspectives of their application in nanomedicine.