The construction of nanozymes at the atomic level that hold structural stability and high enzyme-like activity is now a key factor in the optimization of an artificial enzyme. Single-atom metal/cerium oxide (CeO2)-based nanozymes have been demonstrated to possess a variety of enzymatic activities and radical scavenging abilities, which are mainly attributed to the single-atom active site, redox valence states, and abundant defect chemistry. Here, we developed a single-atom Pd/CeO2 nanostructure by aqueous phase synthesis that exhibits the advantages of high yield and good stability. The Pd/CeO2 nanostructure possesses peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities as well as reactive nitrogen species free-radical scavenging activity, exhibiting multienzyme-like activities and stability compared with CeO2 and other metal-based nanozymes. It is worth mentioning that the Pd/CeO2 nanostructure exhibits high POD-mimicking activity with a reaction rate of 0.88 μM/min, about 5 times higher than that of the CeO2 nanozyme. In addition, the CAT-like activity of the Pd/CeO2 nanostructure is excellent, and its scavenging rate of hydrogen peroxide reached nearly 100% at a concentration of 50 ng/μL. The present work shows that single-atom Pd substitution is a promising strategy for the design of CeO2 nanozymes to exert better effects on biomedical applications, especially with diseases related to oxidative stress.

Artificial enzymes show prospects in biomedical applications due to their stable enzymatic catalytic activity and ease of preparation. CeO2 nanozyme represents a versatile platform showing multiple enzyme-mimicking activities, despite the...

Redox‐active nanozymes offer low‐cost controlled synthesis, high stability, and tunable catalytic properties over natural enzymes, which have attracted wide attention in the field of disease diagnosis and treatment. However, the improvement of catalytic activity remains an important challenge for nanozymes. Herein, the Au/CeO2 nanozymes is developed to achieve enhanced multiple enzyme‐mimetic activity. The Au/CeO2 nanozymes at 5% doping possess best peroxidase‐like activity with threefold higher catalytic rate than CeO2. For catalase‐mimic catalysis, the Au/CeO2 nanozymes at 5% doping also exhibited a 1.5‐fold enhanced reaction rate higher than pure CeO2. The superoxide dismutase (SOD)‐like capacity of Au/CeO2 nanozymes is proportional to Au content. The Au/CeO2 nanozymes at 10% doping show optimal SOD‐like capacity of 60.2 U mg−1. In vitro experiments validate the regulation ability of intracellular oxidative stress and inflammation. Au/CeO2 nanozymes can reduce lipopolysaccharide‐ or H2O2‐induced oxidative damage by scavenging excess ROS in nerve cell. Therefore, Au/CeO2 can be used as a promising antioxidant in disease treatment, and the study offers general guidelines for achieving enhanced biocatalytic property through atomic doping.