Aromatic amino acids adsorption on graphyne: a density functional theory study

To explore the possibility of using graphyne-based biosensors, adsorption of aromatic amino acids on graphyne has been investigated. We have studied the effect of phenylalanine, tryptophan, and tyrosine molecules on the electronic properties of graphyne within density functional theory. The optimal adsorption position, orientation, and distance of these molecules adsorbed on graphyne sheet have been determined by calculating binding energy. The calculated binding energies indicate that the aromatic amino acids are chemisorbed on the graphyne. In the presence of these amino acids, the semimetallic alpha-graphyne and beta-graphyne show metallic behavior, while the semi-conducting gamma-graphyne becomes n-type semiconductor. The energy band gap of gamma-graphyne is decreased by the amino acids adsorption. Our results reveal that the electronic properties of graphyne are sensitive to the aromatic amino acids adsorption; thus, graphyne-based biosensors can be used for detection of these molecules.