Density functional theory (DFT) study of a new novel bionanosensor hybrid; tryptophan/Pd doped single walled carbon nanotube

•Investigation of the adsorption of Tryptophan on Pd/SWCNT.•Tryptophan adsorbed on Pd/SWCNT system demonstrate a strong chemisorption.•Study of a new novel bionanosensor hybrid; tryptophan/ Pd doped single walled carbon nanotube.

In order to explore a new novel l-amino acid/transition metal doped single walled carbon nanotube based biosensor, density functional theory calculations were studied. These hybrid structures of organic-inorganic nanobiosensors are able to detect the smallest amino acid building block of proteins. The configurations of amine and carbonyl group coordination of tryptophan aromatic amino acid adsorbed on Pd/doped single walled carbon nanotube were compared. The frontier molecular orbital theory, quantum theory atom in molecule and natural bond orbital analysis were performed. The molecular electrostatic potential and the electron density surfaces were constructed. The calculations indicated that the Pd/SWCNT was sensitive to tryptophan suggesting the importance of interaction with biological molecule and potential detecting application. The proposed nanobiosensor represents a highly sensitive detection of protein at ultra-low concentration in diagnosis applications.