Using Se8 selenium and cyclic peptides and nanoparticles (SeCPNP), six configurations for the adsorption of the 5-fluorouracil (FU) anticancer drug on SeCPNP have been examined (SeCPNP/FU1-6). Binding energies, solvation energies and quantum molecular descriptors such as electrophilicity (ω) and global hardness (η) in the aqueous solution and gas phase were studied at the density functional level of M06-2X. The most stable structure by binding energy calculations was determined. The values obtained from solvation energies indicate that SeCPNPs can increase the solubility of FU, which is a key factor in drug delivery. According to quantum molecular descriptors, the reactivity of cyclic peptide (CP) and FU drug in all structures (SeCPNP / FU 1-6) increases. AIM calculations for all structures show that Se-A interactions (A = O, H, N, F, C) and intermolecular hydrogen bonding play an important role for this drug delivery system. In structures where FU is parallel to SeCPNP and undergoes interactions concurrently with Se8 and CP, it is more stable than structures in which the drug undergoes interactions only with Se8 and CP.