Study On The Interaction Between AIN, SiC Nanotubes And Small Biomolecules By First Principle Calcualtions

Scientists have made wide and deep research studies on the interactions between biomolecules and nano materials over the last decade. Owing to their unique structural and amazing physical&chemical properties, the AIN and SiC quasi-one-dimentional materials have broad prospects in the field of bio medicine. However, given the complexity of the interested systems and limited experimental techniques, fundamental understanding of how the nanomaterials interact with a biomolecule at atomic level still remains unclear. Thus, in this thesis, density functional theory calculations have been performed to investigate the interaction mechanism between small biomolecules and AN and SiC nanotubes. Besides, we have explored the potential applications of SiC nanotubes based on these calculation resutls. The main results of this thesis are listed below.1. We investigated the adsorption of three representative amino acids, namely, tryptophan (Trp), aspartic acid (Asp) and histidine (His), and five nucleic acid bases, namely, adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) on the outer wall of a high curvature semiconducting single-walled (7,0) aluminum nitride nanotube(AIN) by density functional theory calculations. The three amino acids and four nucleic acid bases (A, G, C, U) show chemisorptions on the aluminum nitride nanotube with appreciable adsorption energies and much charge transfer, which suggests that aluminum nitride nanotube is a good material for biosensing for the above small biomolecules. For amino acids, the interaction strength depends on the chemical nature of its side groups. As to the nucleic acid base, it tends to interact electrostatically with the polar network of aluminum nitride nanotube surface.2. The adsorptions of nucleic acid bases, namely, adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) on the outer walls of intrinsic and boron/nitrogen-doped single-walled (7,0) silicon carbide nanotubes (SiCNT) have been systemically investigated, which reveals that introduction of dopants into SiCNT can improve the sensing properties of SiCNT. It is found that the adsorption energies between nucleic acid bases and SiCNT seems relatively weak, which indicates that the un-modified SiCNT is not an ideal candidate for biosensing. After introducing dopants into SiCNT, the interaction energy between nucleic acid bases and SiCNT could be strengthened. Besides, there is always an optimal doped SiCNT for every nucleic acid base.