Abstract
•The maximum capacity for delivering 5-FU at B40, Au@B40 and Au4@B40 was examined.•B40 and Au4@B40 have a high capacity for delivering of multiple 5-FU molecules.•The 5-FU can be separated from B40, Au@B40 and Au4@B40 at ambient temperature.•Protonation of 5-FU facilitate the nanocarrier to release in the tumor tissues.•The solvent effects of 5-FU at B40, Au@B40 and Au4@B40 nanocages were investigated.
Based on extensive first-principles calculations, the potential of borospherene (B40) and its exohedral metalloborospherene (Au@B40 and Au4@B40) for delivery of 5-fluorouracil (5-FU) is examined using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). To investigate the maximum capacity for delivering 5-fluorouracil (5-FU) molecules, up to four Au atoms can be anchored on the exterior surface of the B40 simultaneously, each of Au has the ability to interact with one 5-FU molecule, using only one B40 molecule. The 5-FU can be easily separated from B40, Au@B40 and Au4@B40 at ambient temperature due to the moderate binding energies and charge-transfer. To comparatively analyze the interaction properties of 5-FU anti-cancer drug at B40, Au@B40 and Au4@B40 nanocages, the electronic properties, charge distributions, frontier orbital, energy gaps and dipole moment have been examined. Moreover, the natural bond orbital analyses (NBO), the projected densities of states (PDOS) properties, non-covalent interactions (NCI), quantum theory of atoms in molecules (QTAIM) and statistical thermodynamic of these systems were used to investigate the interaction process. The time-dependent density functional calculations (TD-B3LYP) were utilized to simulate UV–visible electronic absorption spectra in the gas and aqueous phases. The results reveal that the 5-FU can be simply protonated in the tumor tissues, facilitating the drug to be released from the B40, Au@B40 and Au4@B40 nanocages. The solvent effects tend to reduce the 5-FU binding energies in all (5-FU)@B40, 5-FU@[Au@B40], (5-FU)4@B40 and (5-FU)4@[Au4@B40] complexes. This is the first study to show that borospherene (B40) and metalloborospherene have a high capacity for delivering of multiple 5-FU molecules.