A theoretical study on the pure and Mn-doped graphyne as a propylthiouracil drug delivery system

B3LYP was employed as a density functional to inspect the impact of Mn doping on the ability of graphyne (Gr) in the delivery of the propylthiouracil (PTU) drug. The interaction between the pure Gr and PTU was weak. Doping of the Mn metal into the Gr surface raised the PTU adhesion energy from −6.1 to −28.3 kcal mol⁻¹, and PTU prefers to attach through its O atom to an Mn of the Mn-doped Gr (Mn@Gr). The analysis of partial density-of-states demonstrated that Mn substantially contributes to generating the virtual orbitals of Mn@Gr. It indicates the suitability of Mn, in contrast to the C atoms of Gr, for the nucleophilic attack. In addition to substantial energy release, the electronic properties of Mn@Gr were appreciably sensitive to the attachment of PTU, making it possible for recognizing the trajectory of the drug. A drug release mechanism was provided in cancer tissues, demonstrating that in cancer cells with a low pH, PTU and Mn@Gr were protonated significantly, thus separating PTU from the surface of Gr. Finally, there was a change in the reaction mechanism of PTU with Mn@Gr from covalent bonding in the natural environment to the H-bonding in the acidic environment of cancerous cells.