RuC nanosheet as a promising biosensing material for detecting the aromatic amino acids: a DFT study

Density functional theory (DFT) calculations were performed to examine the potential of the RuC nanosheet as a biosensor towards the aromatic amino acids (AAA; tryptophan (TRP), histidine (HIS), tyrosine (TYR), and phenylalanine (PHE)). The AAA molecules were placed vertically and horizontally with respect to the RuC surface and then subjected to geometrical relaxation. According to the geometry relaxation results, it was found that all AAA molecules preferred to be adsorbed on the RuC surface in a horizontal configuration rather than a vertical one, except the HIS molecule, which desired to be vertically adsorbed on the RuC nanosheet. From the energy manifestations, the adsorption process within the TRP⋯RuC complexes had the greatest desired negative adsorption energy (E _ads), followed by HIS⋯, TYR⋯, and then PHE⋯RuC complexes (E _ads = -40.22, -36.54, -23.95, and -16.62 kcal mol^-1, respectively). As indicated by the FMO data, changes in the E _HOMO, E _LUMO, and E _gap values of the RuC nanosheet following the adsorption process demonstrated the capacity of the RuC nanosheet to adsorb the AAA molecules. The outcomes of Bader charge transfer revealed that the RuC nanosheet had the ability to donate electrons to the AAA molecules during the adsorption process, supported by the positive Q _t values. Consistent with the E _ads conclusions, the TRP⋯RuC complexes had the largest Q _t values, indicating the potential affinity of the RuC nanosheet to adsorb the TRP molecule. Following the adsorption of AAA molecules on the RuC nanosheet, new peaks and bands were discovered based on the DOS and the band structure plots, respectively, revealing the validity of the adsorption process. Additionally, the current adsorption findings on the RuC nanosheet were compared to those on the graphene (GN) nanosheet. The outcomes of the comparison demonstrated the outperformance of the RuC nanosheet over the GN nanosheet in adsorbing the AAA molecules. These outcomes provide a solid foundation for further research on the RuC nanosheets to detect small biomolecules.