Single-Atom Pd/CeO₂ Nanostructures for Mimicking Multienzyme Activities

Abstract

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.

Attapulgite Doped with Fe and Cu Nanooxides as Peroxidase Nanozymes for Antibacterial Coatings

“…The result reveals that Fe-Cu/ATP prepared by precursor solutions containing 0.03 M Cu ions and 0.07 M Fe ions exhibits the best catalytic activities (Figure c). To better quantify the POD-like activity of ATP and Fe-Cu/ATP, the specific activity ( a nano ) was calculated according to relevant studies. , Figure d shows that Fe-Cu/ATP has a nano of 0.304 U mg –1 , which is 8.86 times more than that of ATP (0.0343 U mg –1 ). The increased POD-like activity of Fe-Cu/ATP is attributed to the increased Fe and Cu contents and Fe 2+ /Fe 3+ ratio, , which can generate more · OH with H 2 O 2 through the Fenton-like reaction.…”

Neuron devices: emerging prospects in neural interfaces and recognition

“…First, more sensitive neuron devices need to be developed to overcome the limitations of low sensitivity for neural signal recording 13,31,[109][110][111][112][113] . The design of implant electrodes with smaller size and higher spatiotemporal resolution of sensors, such as optogenetic nanomaterials, biosensors and chemical sensors, may enable long-term sensitive signal recording 6,32,33,[114][115][116][117][118] . Second, biocompatibility is important for the development of neuron devices.…”

Multi-Mimic Activities of Co3O4 Nanopolyhedrons and Application in Regulating the Content of Intracellular Hydrogen Peroxide/Oxygen

“…Various nanoenzymes have been applied in biosensors, biological imaging, environmental analysis, protection and cancer treatment . For example, SOD-like activity can effectively transform intracellular ·O 2 – into hydrogen peroxide and oxygen, and POD can transform intracellular H 2 O 2 into reactive oxygen species (ROS) by converting intracellular H 2 O 2 , and CAT-like activity can transform H 2 O 2 into O 2 . Therefore, the nanozyme activities of nanomaterials may regulate the level of the intracellular H 2 O 2 and O 2 .…”

“…26 For example, SOD-like activity can effectively transform intracellular •O 2 − into hydrogen peroxide and oxygen, 27 and POD can transform intracellular H 2 O 2 into reactive oxygen species (ROS) by converting intracellular H 2 O 2 , 28 and CAT-like activity can transform H 2 O 2 into O 2 . 29 Therefore, the nanozyme activities of nanomaterials may regulate the level of the intracellular H 2 O 2 and O 2 . Among the transition metal-based nanozymes, Co 3 O 4 NPs 30 and nanoflowers 31 have attracted much attention due to their multi-enzyme activities.…”