Imidazole-stabilized gold nanoclusters with thiol depletion capacity for antibacterial application

Surface ligand plays a crucial role in regulating the physicochemical properties and functionalities of gold nanoclusters (AuNCs). Compared to the widely studied thiolate-stabilized AuNCs, the reports on imidazole-based ligands to protect AuNCs are still rare. Herein, we report the facile preparation of imidazole-stabilized AuNCs using 1-vinylimidazole as both a reducing and capping agent. The coordination pattern of imidazole ring to Au core was proved by formation of Au-N bond, which can protect the AuNCs with moderate stability against different pH and temperature. Owing to the weaker binding strength of Au-N bond than Au-S bond, the obtained AuNCs possessed thiol depletion capacity due to ligand exchange in the presence of thiol compounds. By consuming the cellular bio-thiols that act as the reducing species in redox balance, the imidazole-protected AuNCs can cause the accumulation of oxidizing species and the elevation of the oxidative stress. Accordingly, the obtained AuNCs exhibited intrinsic antibacterial activity toward Staphylococcus aureus, which could be a promising bactericidal nanomaterial for sterilization.