Molecular dynamics simulations and quantum chemical calculations of GEMZAR in surface-modified carbon nanotube

Abstract

Understanding of molecular properties of the encapsulation of the GEMZAR anticancer drug in the single-walled carbon nanotube (SWCNT) is the main goal of this study. The molecular geometries of the pristine and functionalized SWCNTs were studied by the simiempirical PM3 method. It was found that modification on the outer surface of the tube by the –COOH and –OH functional groups leads to the lowered planarity of the tube surface. Then, MD simulations were applied to investigate structural and dynamical properties of the GEMZAR in free and the pristine SWCNT bound states. As a result, the drug was found to move freely from one end to the other of the SWCNT, not along the tube axis at the center of the tube but parallel at the distance of 4.7 Å from the inner surface. Using the structural data, the angle between the cytosine-based and the inner surface of 19o was yielded, indicating that the drug always positioned inside the tube and partially interacted with the surface through the aromatic stacking interaction. The most probable conformation of the cytosine-based and ribose rings in both states was relatively similar. In addition, drug molecule was weaker and less solvated in which the SWCNT than that of the free state because of the collaborative interaction with the inner surface of the tube. Furthermore, overall drug properties inside the functionalized SWCNTs modified by the –COOH and –OH groups were considerably similar to what observed for the pristine SWCNT.