Investigation of the phosphorene nano-sheet as a sensor for detecting aspartic-acid, alanine and glycine amino acids: A first principle study

In this study, we have theoretically investigated the application of phosphorene nano-sheet as a biosensor for detecting some amino acids such as alanine, glycine and aspartic-acid using density functional theory (DFT). The results of the electronic properties show that the phosphorene nano-sheet has a direct band gap of about 0.84 eV and the presence of alanine, glycine and aspartic-acid adsorbed on the surface of phosphorene reduces the band gap slightly. The charge transfer analysis between phosphorene nano-sheet and the amino acid molecules shows that aspartic-acid molecule acts as an electron donor, while alanine and glycine molecules act as electron acceptors. Our calculations demonstrate that there is a strong anisotropy in electron/hole effective mass mh*) mh*) along armchair and zigzag directions of pristine and molecular adsorbed phosphorene. This leads to a quenching of conductivity in the zigzag direction with respect to the armchair direction. Based on the changes of electron/ hole effective mass of phosphorene under the influence of the adsorption of the amino acid molecules, we have suggested a phosphorene-based biosensor. This biosensor has the best sensibility and selectivity when measuring hole effective mass along the armchair direction. The maximum sensibility was found to be around 59.3% to aspartic acid molecule. Our findings confirm that phosphorene nano-sheet can be applied as a promising biosensor for detecting amino acid molecules.