Understanding the mechanism of thioguanine's binding to Ag6 and bimetallic (Ag3–Au3 and Ag3–Cu3) clusters

Abstract

Using Ag6, Ag3Au3 and Ag3Cu3 clusters, density functional theory (DFT) methods were used to elucidate the interaction behavior of thione-containing thioguanine drug (TGN) on silver. The CAM-B3LYP functional with LANL2DZ basis set was used to study the different features and bonding qualities of resultant metal complexes. The drug molecule tends to anchor on the cluster with binding energies ranging from −16 to −23 kcal/mol. Due to the recovery time values and change in energy gap, the metal clusters can be turned into an electrical signal for detecting TGN. TGN-metal cluster interactions are reversible events, and a drug release mechanism has been postulated. As a result of a modest change in pH in tumor cells, the drug is able to detach from metal surfaces. Non-covalent interactions studies show that TGN's NH2 group is more important for hydrogen bonding, and the heterocyclic N and S atoms may play a role in weak interactions.