Modulation the electronic property of 2D monolayer MoS2 by amino acid

2D molybdenum disulfide (MoS2) has a strong potential for the detection of biomolecules, however, the specific interactions between individual amino acids and MoS2 surface are still unclear. Herein, the adsorption properties and electronic structures of amino acid/MoS2 systems were investigated systematically for the 20 standard amino acids based on density functional theory. The adsorption strength of amino acids on MoS2 monolayer decreases in the following order: TRP > ARG > PHE > TYR > LYS > HIS > PRO > ASN ≈ MET > LEU > ILE > VAL > GLU > GLN > THR > ASP > CYS > SER > ALA > GLY. The band gap of amino acid/MoS2 system is determined by the energy level of HOMO orbit of the adsorbed amino acid, in which the higher energy level of HOMO orbit will result in a smaller band gap. As proof of concept, optical and electrical detection of the MoS2 based transistors with and without amino acid molecules (TRP and CYS) were studied. Adsorption of amino acids on a MoS2 surface allows their chemical information to be transformed into distinct analytically optical and electronic signals, which opens up new possibilities for fabricating novel MoS2 based highly selective biosensors.