DFT study of carboplatin encapsulation interactions with carboxylated carbon nanotubes and conjugated to folic acid for targeted nano delivery systems

In this study, a nano-drug delivery design based on (8, 8) carboxylated single-walled carbon nanotube (CNT-COOH) and folic acid (FA) decorated on CNT-COOH (CNT-FA) were investigated. These nanocarriers were applied to enhance therapeutic efficacy and reduce the adverse effects of the anticancer drug carboplatin (CBP) and the results were compared. The density functional theory (DFT) calculations were used to calculate the interactions between CNT-COOH, CNT-FA, and the CBP anticancer drug. The DFT computations were carried out by the DMol³ module using annealing and force field; universal in Material Studio 2017. The negative adsorption value of CBP by CNT-COOH and CNT-FA demonstrated that the physisorption configuration was stable and the drug-nanotube sidewall interaction was a spontaneous process. The current study investigated the adsorption strength and energy between the CBP molecule and CNT-COOH (8, 8) nanotubes with diameters of 12.160 Å and 11.674 Å and CNT-FA with diameters of 11.874 Å and 10.608 Å in the gas phase based on DFT calculations. The HOMO and LUMO energies of all compounds were obtained by the DMol³ module based on DFT-D. Also, sigma profile calculations (σ), energy gap (ΔE_gap), and molecular electrostatic potentials (MEP) of CBP, CNT-COOH, CBP/CNT-COOH, CNT-FA, and CBP/CNT-FA were calculated. The results of ΔE_gap confirmed the higher activity of the CBP/CNT-FA component (0.243 eV) compared to other structures. Molecular docking simulations between nano-carriers, including with or without CBP, and the crystal structure of human folate receptor alpha (FR, PDB ID: 4LRH), were performed. The results exhibited CNT-FA and CBP/CNT-FA were stronger on folate receptor compared with CNT-COOH and CBP/CNT-COOH, respectively.