Comprehensive quantum chemical insight into the mechanistic understanding of the surface functionalization of carbon nanotube as a nanocarrier with cladribine anticancer drug

Abstract

Using molecular models for pristine (NT) and COOH (FNT) functionalized carbon nanotube, ten noncovalent configurations and four mechanisms of covalent functionalization of NT and FNT with cladribine anticancer drug (CDA) were studied. Quantum molecular descriptors, free energies of solvation and binding energies of noncovalent interactions were investigated in H2O and DMF solvents and gas phase. The calculation of binding energies confirmed the energetic stability of all CDA/NT and CDA/FNT configurations. The free energies of solvation show that NT and FNT solubility increases in all drug-nanotube configurations which is a main factor for its applicability in the drug delivery. Quantum molecular descriptors of drug such as global hardness and HOMO-LUMO energy gap are higher than those of drug-nanotube complexes, showing the reactivity of the drug increases. The AIM analysis for the most stable configuration (CDA/FNT2) demonstrated that the intermolecular hydrogen bonding plays a main role in this system. For the covalent functionalization COOH (FNT) and COCl (NTCOCl) functionalized carbon nanotubes were considered. Cladribine may bond to FNT and NTCOCl through NH2 and OH groups. The activation parameters of all pathways were calculated, indicating the activation energies and Gibbs free energies related to FNT mechanisms are higher than those of NTCOCl mechanisms.