DFT calculations to investigate silver ions as a virucide from SARS-CoV-2

The world has face the COVID-19 pandemic which has already caused millions of death. Due to the urgency in fighting the virus, we study five residues of free amino acids present in the structure of the SARS-CoV-2 spike protein (S). We investigated the spontaneous interaction between amino acids and silver ions (Ag(+)), considering these ions as a virucide chemical agent for SARS-CoV-2. The amino acid-Ag(+) systems were investigated in a gaseous medium and a simulated water environment was described with a continuum model (PCM) the calculations were performed within the framework of density functional theory (DFT). Calculations related to the occupied orbitals of higher energy showed that Ag(+) has a tendency to interact with the nitrile groups (-NH). The negative values of the Gibbs free energies show that the interaction process between amino acids-Ag(+) in both media occurs spontaneously. There is a decrease in Gibbs free energy from the amino acid-Ag(+) interactions immersed in a water solvation simulator.