A DFT approach to the adsorption of the Levodopa anti-neurodegenerative drug on pristine and Al-doped boron nitride nanotubes as a drug delivery vehicle

The adsorption behavior of the anti-neurodegenerative drug Levodopa (LD) on pristine and aluminum-doped (Al-doped) boron nitride nanotubes (BNNTs) has been investigated in the current study using the density functional theory (DFT) approach at the B3LYP/6-31G* level of theory. The aim was to improve and expand boron nitride nanotubes drug carriers used in biomedical systems, i.e., drug delivery systems. The binding qualities of pure and doped BNNT complexes as adsorbents with LD were explored using the natural bond orbitals (NBO) analysis, density of state (DOS), electrical and structural characteristics, and atoms in molecules (AIM) properties. Due to doping heteroatoms in the adsorbent's molecular structure, the obtained data reveal a gradual shift in LD adsorption, with a significant rise in negative adsorption energy values. The electronic perturbation caused by doped atoms, particularly Al, improves boron nitride nanotube sensitivity to adsorbed Levodopa, and the electronic properties of the nanotubes are altered following Levodopa adsorption in the complex. As the frontier molecular orbital distributions were transferred from LD to BNNTs in the complex of BNNT-LD, it was also shown that LD drugs could be loaded on pristine and Al-doped BNNTs while remaining safe from interactions with other substances. Furthermore, AIM analysis based investigations revealed that O-Al interaction in LD adsorbed on Al-doped boron nitride nanotube and O-N interaction in the BNNT-LD complex are partially covalent. Finally, the findings showed that pristine and Al-doped BNNT could be used in drug delivery processes by controlling the loaded LD contribution to future interactions.