Au-Au/IrO₂@Cu(PABA) Reactor with Tandem Enzyme-Mimicking Catalytic Activity for Organic Dye Degradation and Antibacterial Application

Herein, a Au-Au/IrO₂ nanocomposite with tandem enzyme-mimicking activity was innovatively synthesized, which can show outstanding glucose oxidase (GOx)-like activity and peroxidase-like activity simultaneously under neutral conditions. Moreover, a Au-Au/IrO₂@Cu­(PABA) reactor was prepared via encapsulation of the Au-Au/IrO₂ nanocomposite in a Cu­(PABA) metal organic framework. The reactor not only exhibits excellent organic solvent stability, acid resistance, and reusability but also displays better cascade reaction catalytic efficiency (k_cat/K_m = 148.86 min^–1 mM^–1) than the natural free enzyme system (GOx/HRP) (k_cat/K_m = 98.20 min^–1 mM^–1) and Au-Au/IrO₂ nanocomposite (k_cat/K_m = 135.24 min^–1 mM^–1). In addition, it is found that the reactor can catalyze glucose or dissolved oxygen to produce active oxygen species (ROS) including HO, ₁O², and O₂^–· through its enzyme-mimicking activity. Finally, the novel reactor was successfully used in organic dye degradation and antibacterial application. The results show that it can effectively degrade methyl orange, methylene blue, and rhodamine B, which all can reach a degradation rate of nearly 100% after interacting with Au-Au/IrO₂@Cu (PABA) for 3.5 h. Furthermore, the reactor also exhibits excellent antibacterial activity, so as to achieve a complete bactericidal effect to Staphylococcus aureus and Escherichia coli at a concentration of 12.5 μg mL^–1.