In this study, the adsorption of the 5-fluorouracil (5-FU) anticancer drug with graphene quantum dots (GQDs) and its doping form with nitrogen (N) and copper (Cu) was investigated using density functional theory (DFT) by applying D3 dispersion correction. Energy level of molecular orbitals, atomic charge distribution, electron localization function (ELF), independent gradient model based on Hirshfeld partition (IGMH), partial density of state (PDOS), Fourier transform infrared spectrum (FTIR), ultraviolet visible (UV–Vis) spectrum, drug adsorption energy, as well as thermodynamic calculations such as Gibbs free energy (ΔG), and enthalpy (ΔH) changes were applied in detail. Results showed that Cu-N-doped GQDs had high chemical reactivity, which was crucial for the binding of the drug onto the target site of the adsorbent. In addition, doping GQDs with a Cu atom could significantly enhance the tendency of the adsorbent for 5-FU adsorption. Accordingly, the 5-FU adsorption energies on the studied adsorbents are as follows: Cu-4 N-doped GQD > Cu-3 N-doped GQD > 4 N-doped GQD > 3N-doped GQD > GQD. Furthermore, Gibbs free energy changes indicated that the adsorption of the 5-FU drug on the Cu-N-doped GQDs surfaces occurred spontaneously. The Gibbs free energy changes of 5-FU adsorption on the studied adsorbents are: GQD > 3 N-doped GQD > 4 N-doped GQD > Cu-3 N-doped GQD > Cu-4 N-doped GQD. In conclusion, Cu-N-doped GQDs can be proposed as a potential carrier for 5-FU delivery to the tumor cells.

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