Comprehensive theoretical analysis of gabapentin antiepileptic adsorption on pristine and Al-doped boron nitride nanotubes surface as a drug delivery vehicle: A DFT study

Abstract

In this study, the interaction between the drug gabapentin and boron nitride nanotubes (BNNTs) was investigated, along with the effect of aluminum doping (Al-BNNTs). Using density functional theory (DFT) calculations, key properties such as structural parameters, energy gap, dipole moment, and density of states (DOS) were analyzed for four different configurations of drug adsorption onto the BNNT surface. The results revealed that the angle of molecular approach and the alignment of the drug's dipole moment are significant. From a chemical perspective, the dominant interactions in the pristine BNNT-drug complexes are noncovalent in nature, including van der Waals forces and hydrogen bonding. However, aluminum doping promotes the formation of covalent or semi-covalent bonds, especially between the aluminum atom and functional groups of gabapentin, leading to enhanced structural stability. Additionally, doping was found to reduce the energy gap, introduce mid-gap states near the Fermi level, and improve surface conductivity. We explored optimized geometries, adsorption energies, quantum molecular descriptors, topological parameters, and frontier molecular orbitals of different drug configurations on GBP/BNNTs and GBP/Al-BNNTs at the B3LYP/6–31 + G(d) level of theory in gas phases. To further investigate the nature of these interactions, Reduced Density Gradient (RDG) analysis was used to visualize weak noncovalent forces, and Natural Bond Orbital (NBO) analysis provided insight into charge transfer (CT) and bond hybridization mechanisms. Moreover, doping reduced the energy gap, introduced mid-gap states near the Fermi level, and improved surface conductivity, as confirmed by DOS plots. These findings highlight the potential of Al-doped BNNTs as effective nanocarriers for drug delivery applications.