Investigating the Adsorption of the Thyroid Stimulating Hormones Molecules on Graphene Sheets by the Density Functional Theory for Possible Nano-Biosensor Applications

In this paper, the electronic effects of the adsorption of thyroid-stimulating hormones (TSH) on two-dimensional structures of graphene and ψ-graphene are theoretically investigated utilizing the density functional theory (DFT). Initially, the binding energies of TSH molecules on graphene (both the zigzag and armchair structures) and ψ-graphene are computed at different spatial orientations using the Siesta code. The most stable orientations had the following binding energies: –1.04 eV for triiodothyronine on graphene, –1.25 eV for thyroxine on graphene, –0.97 eV for triiodothyronine on ψ-graphene, and –0.95 eV for thyroxine on ψ-graphene. After identifying the most stable orientations, the current-voltage characteristics of graphene and ψ-graphene monolayers, before and after the adsorption of TSH molecules are calculated by the TranSiesta computational software package, using the non-equilibrium Green’s function approach. The adsorption of the TSH molecules on both graphene structures reduced the passing electric current significantly. The findings show that graphene sheets can be used to synthesize fast responding TSH nano-biosensors.