Theoretical study of the encapsulation of the anticancer drug of letrozole: DFT/TD-DFT and Spectroscopic Studies

Objective: The DFT description and comparison of the loading of Letrozole (LTZ) on boron nitride (AlNNT) and aluminum nitride (BNNT) nanotubes were studied herein. The results of the thermochemical parameters indicate that LTZ with AlNNT nanotube would be a more spontaneous and exothermic process in comparison with that of BNNT. The study included electron delocalization effects, stereoelectronic interaction, steric repulsion effects, electronic properties, and reactivity of LTZ on the AlNNT nanotube using DFT B3LYP/6-31G* level of theory.
Methods: The UV-Vis absorption analysis and the IR spectrum were used to ascertain the changes that take place on adsorption of LTZ onto AlNNT. The molecular orbital distribution was further assessed to monitor electronic structure changes, adsorption energies (Ead), and electrical conductivity during the adsorption process on both substrates.
Results: The NBO analysis of the LTZ-AlNNT complex shows that the highest resonance energy is provided due to the instability of electrons of LP(1)N73→ BD*(2)N75-C85 (51.96 kcal.mol-1), which in turn signifies that there is electron transfer from the LTZ drug in the LTZ-AlNNT complex. This in the UV-Vis spectrum corroborated by the drug adsorption-related wavelength change from 226.7 nm to 254.3 nm on the AlNNT demonstrates bathochromic shift.
Conclusion: We hope that this study can aid in modeling and designing a suitable adsorbent for drug delivery based on its findings. Thus, electronic, thermochemical, and structural properties of LTZ drug complexes with the nanotubes AlNNT and BNNT were elucidated with a combination of DFT calculations and graphical analysis of the non-covalent interactions index (NCI) analysis.