The Interaction of Sulfamethoxazole Drug with the Pristine and Functionalized C60 Fullerenes: A DFT Study

Adsorption properties of sulfamethoxazole drug on the pristine (C-60) and functionalized (C(60)HNH2) fullerenes in different situations were calculated by density functional theory calculations using the omega B97XD method and 6-31G(d) standard basis set in gas and solution phase. Based on the adsorption and Gibbs free energies, the adsorption of sulfamethoxazole on the pristine C-60, in all situations, was unfavorable, but its adsorption on the functionalized fullerene was spontaneous and favorable, in two situations. Also, in agreement with the Gibbs free energy data, functionalized fullerene has negative solvation energy in two situations, therefore, it can be suitable as a nano-carrier in drug delivery systems. In addition, the nature of interaction between sulfamethoxazole and functionalized fullerene in the most favorable situation was analyzed by the independent gradient model based on Hirshfeld partition (IGMH). The [4+2] cycloaddition reactions of SMX with the fullerenes were also studied and the results ruled out the possibility of chemical adsorption via such reactions.