DFT/NBO analysis of interaction between a CNT and anti-cancer drugs

Having conducted fundamental projects, scientists have expressed their hope to develop the use of carbon nanotubes to release drugs. It is important to release drugs in cell without damaging healthy cells of tissues under study. Researchers have shown the fact that nanotubes can perform this function perfectly. To this objective, in the present study the interactions between four anti-cancer drugs with a carbon nanotube (CNT) (6,6), containing 60 carbon atoms, have been investigated. It is noteworthy that all of these drugs have functional groups, from which the reaction with the nanotube can take place. The Density Functional Theory (DFT) calculations have been performed by Beck, three-parameter, Lee-Yang-Parr (B3LYP) method and 6-31G(d) basis set for full optimization of drugs, nanotube and the formed complexes. The Natural Bond Orbital (NBO) analysis and frequency calculations have been also performed for all structures using B3LYP method and 6-31G(d) basis set in 298K. According to the results, among all drugs under study, only two complexes between Carmustine and nanotube can be thermodynamically formed in 298K. The stability constants are calculated thereby showing a considerably large amount. Therefore, the nanotube can be a useful container for this drug. Also, NBO analysis shows that there exist hyperconjugative effects arising from an overlap between occupied orbitals in drugs and unoccupied orbitals in nanotube.