Doped boron phosphide nanotubes for nedaplatin transportation: a theoretical investigation

Abstract

After the synthesis of carbon nanotubes (CNT), these nanostructures have attracted the attention of scientists because they may be used in molecule transportation. Nanotubes analogous to CNTs, such as boron phosphide nanotubes (BPNTs), in the zigzag chirality, are important because theoretical predictions indicate that they are soluble in polar solvents. Therefore, they may be appropriate for applications in biological systems. We have investigated the structural and electronic properties of the (14,0) BPNTs in pristine form and doped with C/Ti, analyzing their interaction with nedaplatin in different configurations. First-principles total-energy calculations were performed using density functional theory (DFT) within the Quantum ESPRESSO package. Exchange–correlation energies were treated with the generalized gradient approximation (GGA) using the Perdew, Burke, Ernzerhof (PBE) functional, while electron–ion interactions were modeled with PAW pseudopotentials. In all calculations, long-range van der Waals interactions were accounted for by including the Grimme DFT-D2 dispersion correction scheme.

When the molecule forms bonds, it undergoes chemisorption. However, the molecule is physisorbed for the C-doped BPNT (P site), as confirmed by the absence of bond formation. High adsorption energy values are attributed to van der Waals interactions. Negative adsorption energy value means stronger interactions between drugs and nanotubes; however, such high values would not benefit the desorption of the molecule. The most suitable systems are pristine BPNT (−2.04 eV), C-doped BPNT (B site) (−2.28 eV), and C-doped BPNT (P site) (−1.44 eV). Additionally, in the case of Ti, nanotube deformation is observed. Pristine and C-doped nanotubes are more favorable because these systems have adsorption energy that is good enough to bond and not too strong, so desorption is possible.