A DFT study on the therapeutic potential of carbon nanostructures as sensors and drug delivery carriers for curcumin molecule: NBO and QTAIM analyses

Abstract

In this research, the interactions of curcumin molecule with fullerene C60 (F-C60), carbon nanosheet (CNS), and carbon nanotube (CNT) as carbon nanostructures were investigated for drug delivery purposes employing density functional theory (DFT) calculations. Two phases of gas and water were considered for DFT calculations on the investigated models. A stabilized complex of curcumin and nanostructures was obtained in both phases according to the values of adsorption energy. An exothermic reaction was seen according to the negative values of adsorption energy. It was found from the calculations of the quantum theory of atoms in molecules (QTAIM) that the values of electron density in critical points of bond (ρr) were low and positive in all hydrogen bonding complexes. The results of the calculations also indicated the existence of weak interaction forces for noticeable and successful unloading of the curcumin from the carriers at target sites. The density of states (DOS) was investigated to evaluate the effect of molecular adsorption on the electronic properties of the nanostructures, and the results showed that F-C60 was closer to the Fermi energy (red line) than other nanostructures. The values of adsorption energy in the gas phase were higher than those in the water phase, indicating a stronger interaction of the molecule with the nanostructures in the gas phase. According to the values of adsorption energy, curcumin interacted stronger with F-C60 in comparison with other nanostructures. The values of ∆Eg after adsorption of curcumin were − 0.21 eV, − 0.01 eV, and − 0.001 eV for F-C60, CNS, and CNT, respectively, showing that F-C60 was more sensitive than CNS and CNT. The calculations carried out in this study indicated that the nanostructures could be applied as suitable carriers for delivering curcumin.