Drug delivery mechanism of doxorubicin and camptothecin on single-walled carbon nanotubes by DFT study

We used a density functional-based tight-binding method corrected with London-type dispersion to simulate the stable action model of doxorubicin and camptothecin on the surfaces of single-walled carbon nanotubes. In this study, we considered armchair (n, n) (n = 6–10) and zigzag (n, 0) (n = 10–14) carbon nanotubes of different sizes and lengths. The arrangements of the drug molecules doxorubicin and camptothecin on the surface of single-walled carbon nanotubes are discussed in detail, and the size, chirality and length of CNT, and the binding energies of the drug molecules in the stable configuration of the complex were analyzed. The structural properties of the models were further determined by analyzing the action distance between the carbon nanotube surface and representative atoms in the drug molecule. We also analyzed the molecular orbital properties of the stable complexes to further study the binding interactions. The Gibbs free energy of solvation was studied to measure the solubility of the drug delivery complex. By comparing the drug loading mechanism of doxorubicin and camptothecin, it is hoped that this work will provide a theoretical reference for the construction and study of the drug loading model for different types of drugs.