Elucidating the adsorption and detection of amphetamine drug by pure and doped Al12N12, and Al12P12nano-cages, a DFT study

Abstract In this work, the adsorption of amphetamine (AN) drug onto the exterior surface of two fullerene-like nano-cages, Al12N12 (ALN), and Al12P12 (ALP) was studied by density functional theory (DFT) methods and the quantum theory of atom in the molecule (QTAIM) calculations. Our calculations revealed that the amphetamine drug connects to the Al, N, and P, atoms of Al12N12, and Al12P12 nano-cages through two types of interactions partially-covalent partially-electrostatic (polar covalent) and electrostatic interaction in the gas and water phase. NBO analysis confirmed that the charges were transferred from the σ orbitals of C and H atoms of AN drug to the n* orbitals N, Al, and P atoms of ALN and ALP nano-cages with high charge-transfer energies. The binding energies of ALN-AN and ALP-AN complexes were computed and demonstrate that the binding energy of ALP-AN complexes is larger than those of ALN-AN complexes in both gas and water phases. During the adsorption of amphetamine drug onto the ALN and ALP nano-cages, the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were significantly changed, resulting in a decrease in the values of band gap (Eg) that caused enhance in their electrical conductivity. Also, the effect of doping of ALN and ALP nano-cages by Zn, Mg, and Ga atoms on their sensitivity and adsorption of AN drug was studied. AIM analysis shows that there are two types of interactions partially-covalent partially-electrostatic (polar covalent) and electrostatic interaction in the gas and water phase formed between amphetamine and Zn, Mg, and Ga doped ALN, and ALP nano-cages. NBO analysis confirmed that the charges were transferred from the σ orbitals of C and H atoms of AN drug to the n* orbitals N, Al, and P atoms of Zn, Mg, and Ga doped ALN and ALP nano-cages with high charge-transfer energies. Mg, and Ga doped ALN and ALP nano-cages benefit from a short recovery time. Therefore, Mg, and Ga doped ALN and ALP nano-cages can be considered as promising biosensors for AN drug detection. This manuscript illustrated that Mg, and Ga doped ALN and ALP nano-cages may be potential electronic sensors as well as suitable candidates for the delivery of amphetamine drug in the biological system.