The iron group transition-metal (Fe, Ru, Os) coordination of Se-doped graphitic carbon (Se@g-C(3)N(4)) nanostructures for the smart therapeutic delivery of zidovudine (ZVD) as an antiretroviral drug: a theoretical calculation perspective

This study employed density functional theory (DFT) computational techniques at the ωB97XD/def2svp level of theory to comprehensively explore the electronic behavior of Fe-group transition metal (Fe, Ru, Os) coordination of Se-doped graphitic carbon (Se@g-C(3)N(4)) nanosystems in the smart delivery of zidovudine (ZVD), an antiretroviral drug. The HOMO–LUMO results of the interactions show a general reduction in energy gap values across all complexes in the following order: ZVD_Se@C(3)N(4) < ZVD_Ru_Se@C(3)N(4) < ZVD_Fe_Se@C(3)N(4) < ZVD_Os_Se@C(3)N(4). ZVD_Se@C(3)N(4) exhibits the smallest post-interaction band gap of 3.783 eV, while ZVD_Os_Se@C(3)N(4) presents the highest energy band gap of 5.438 eV. Results from the corrected adsorption energy (BSSE) revealed that Os_Se@C(3)N(4) and Ru_Se@C(3)N(4) demonstrated more negative adsorption energies of −2.67 and −2.701 eV, respectively, pointing to a more favorable interaction between ZVD and these systems, thus potentially enhancing the drug delivery efficiency. The investigation into the drug release mechanism from the adsorbents involved a comprehensive examination of the dipole moment and the influence of pH, shedding light on the controlled release of ZVD. Additionally, investigating the energy decomposition analysis (EDA) revealed that ZVD_Ru_Se@C(3)N(4) and ZVD_Fe_Se@C(3)N(4) exhibited the same total energy of −787.7 kJ mol(−1). This intriguing similarity in their total energy levels suggested that their stability was governed by factors beyond reactivity, possibly due to intricate orbital interactions. Furthermore, analyzing the bond dissociation energies showed that all systems exhibited negative enthalpy values, indicating that these systems were exothermic at both surface and interaction levels, thus suggesting that these processes emitted heat, contributing to the surrounding thermal energy.