Density functional study on the adsorption of the drug isoniazid onto pristine and B-doped single wall carbon nanotubes

The current study explores a new strategy to incorporate single wall carbon nanotubes (SWNTs)/doped SWNTs as carrier modules in target-specific administration of antitubercular chemotherapeutics through covalent and noncovalent functionalization onto the nanotube sidewall. Density functional studies illustrate that noncovalent functionalization of isoniazid (INH) is preferred over covalent attachment, exhibiting low adsorption energy values, HOMO-LUMO gap and comparison of quantum molecular descriptors performed in (5,5) and (9,0) SWNT systems. Substitution doping of boron facilitates the adsorption of INH onto the otherwise inert nanotube. Frontier orbital analysis reveals reorientation of electronic charge in the nanotubes after functionalization, the effect being more pronounced in the case of doped nanotubes. The charge transfer is significant in covalent functionalization of INH via the B-dopant atom, whereas in noncovalent functionalization a small amount of charge transfer is noted. Solvation studies demonstrate the dissolution of INH in B-doped (5,5) and (9,0) SWNTs to be higher compared to pristine nanotube-INH complexes. Functionalization of nanotubes via covalent and noncovalent means can foster pioneering prospects especially for experimental studies in this area of research.