Polyoxometalate-Mediated Vacancy-Engineered Cerium Oxide Nanoparticles Exhibiting Controlled Biological Enzyme-Mimicking Activities

Abstract

The biological enzyme-mimetic activity of cerium oxide nanoparticles (CeNPs) is well known to scavenge the reactive oxygen and nitrogen species in cell culture and animal models, imparting protection from the deleterious effects of oxidative and nitrosative stress. The superoxide dismutase (SOD)- and catalase-mimicking activity of CeNPs is reported to be controlled by the oxidation state of the surface “Ce” ions, where a high ratio of Ce3+/4+ or Ce4+/3+ has been considered for the displayed SOD and catalase-like activity, respectively. However, the redox behavior of CeNPs can be controlled by certain ligands that could offer changes in their enzyme-mimetic properties. Therefore, in this work, we have studied the enzyme-mimetic activities of CeNPs under the influence of polyoxometalates [phosphomolybdic acid (PMA) and phosphotungstic acid (PTA)], which are electron-dense molecules displaying quick and reversible multielectron redox reactions. Results revealed that the interaction of PMA with CeNPs results in the inhibition of the SOD-like activity; however, it has no impact on the catalase-like activity. Contrary to this, the interaction of PTA with CeNPs improved the SOD as well as catalase-like activities of CeNPs (3+), which generally do not exhibit catalase activity in the bare form. Although CeNPs (3+) did not show any peroxidase-like activity, CeNPs (4+) showed excellent activity, which was enhanced after the interaction with polyoxometalates. Further, the autoregeneration ability of CeNPs was found to be intact even after PTA or PMA interaction; however, the full catalytic activity was observed in the case of PTA but partially with PMA.

Glucose/ROS cascade-responsive ceria nanozymes for diabetic wound healing

“…Here, the original concentration of cerium ions in the solution was measured by ICP–MS to be 3.5 ​mM ( Fig. S7 ), and the above results suggested that CHA@GOx is promising for applications in the field of enzyme-mimicking catalysis [ 54 ]. Therefore, we next explored the SOD-like enzyme activity of these nanozymes.…”

Manganese dioxide nanosheet-containing reactors as antioxidant support for neuroblastoma cells

“…17,18 Mn 3 O 4 nanoparticles mimicked the catalysis of catalase, glutathione peroxidase (GPx) and SOD 19 that were explored to alleviate reactive oxygen (ROS)-induced challenges. 20,21 We note that there are alternative nanozymes, e.g., cerium oxides 22,23 , that exhibit SOD-like and catalase-like activities.…”

“…20,21 We note that there are alternative nanozymes, e.g. , cerium oxides 22,23 , that exhibit SOD-like and catalase-like activities.…”

Degradation and Detection of Endocrine Disruptors by Laccase-Mimetic Polyoxometalates

“…Over the last decades, POMs have demonstrated their promising biological activities, such as antitumoral ( Bijelic et al, 2019 ), antimicrobial ( Xu et al, 2020 ; Chen et al, 2021 ; Chen et al, 2022 ), insulin-sensitizing ( Chen et al, 2020 ), immune-enhancing activities ( Li et al, 2021 ; Li et al, 2022 ). In virtue of their structural diversity and physicochemical properties, POM-based nanomaterials exert oxidoreductase-mimicking activities, including oxidase, peroxidase ( Chen K. et al, 2018 ; Jia et al, 2019 ), and catalase ( Yadav and Singh, 2021 ). Compared with other nanomaterials, POMs are advantageous in their well-defined composition and molecular structure, as well as their economical production costs and mass production.…”