Quantitatively Intrinsic Biomimetic Catalytic Activity of Nanocerias as Radical Scavengers and Their Ability against H₂O₂ and Doxorubicin-Induced Oxidative Stress

Abstract

Artificial enzymes as radical scavengers show great potentials in treatments of various diseases induced by oxidative stress. Herein, the quantitative analysis indicates that the intrinsic activity of nanocerias for the degradation of radicals is determined by the concentration of surface defects as well as their morphological features. The surface Ce fraction of the CeO nanozymes with a similar morphology can be used as a descriptor to index their catalytic activity as radical scavengers. Defect-abundant porous nanorods of ceria (PN-CeO) with a large surface area (141 m/g) and high surface Ce fraction (32.8%) deliver an excellent catalytic capability for the degradation of radicals, which is 15.5 times higher than that of Trolox. Results indicate that PN-CeO not only provides more surface catalytic centers but also supplies the active site with higher activity. Oxidative stress induced by doxorubicin (Dox), an essential medicine for a wide range of tumors, was used as the model system to evaluate the radical degradation ability of PN-CeO. Both in vitro cellar (H9c2 cells) and in vivo animal models revealed that PN-CeO did not affect the cell and rat growth and was able to alleviate the Dox-induced oxidative stress. Results suggest that the artificial PN-CeO nanozymes have potentials to function as an adjuvant medicine during tumor chemotherapy.

A pH‐Responsive Polymer‐CeO2 Hybrid to Catalytically Generate Oxidative Stress for Tumor Therapy

“…Initially, the in vitro activities of PN CeO 2 and PN CeO 2 PSS on LX‐2 cells were evaluated by incubating various amounts of the catalysts with the cells for 24 h. As shown in Figure S5, Supporting Information, even with high concentrations of PN CeO 2 and PN CeO 2 PSS (250 µg mL −1 ), the viability of the LX‐2 cells in both cases remained over 90%, indicating the high biocompatibility and nontoxicity of PN CeO 2 and PN CeO 2 PSS in normal human cells. [ 49,52,59 ]…”

“…Initially, the in vitro activities of PNCeO 2 and PNCeO 2 PSS on LX-2 cells were evaluated by incubating various amounts of the catalysts with the cells for 24 h. As shown in Figure S5, Supporting Information, even with high concentrations of PNCeO 2 and PNCeO 2 PSS (250 µg mL −1 ), the viability of the LX-2 cells in both cases remained over 90%, indicating the high biocompatibility and nontoxicity of PNCeO 2 and PNCeO 2 PSS in normal human cells. [49,52,59] Tumor cell cytotoxicity assays are a key indicator for further anti-tumor catalytic chemodynamic therapy capability of catalysts. Before the evaluations of the catalytic performance of PNCeO 2 PSS in HepG2 cells, the evolution of the pH of the cell culture medium was monitored and recorded ( Figure S6, Supporting Information).…”

“…Due to its reversible Ce 3+ /Ce 4+ redox pair, nanoceria displays multiple enzyme-like catalytic activities, including peroxidase, catalase, phosphatase, photolyase-like and superoxide dismutase (SOD) activities, all of which significantly depend on the surface defect abundance of CeO 2 as well as the catalytic microenvironment. [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] However, to date, CeO 2 alone has not been observed to exhibit substantial oxidative activity for O 2…”

MOF-Mediated Synthesis of CuO/CeO2 Composite Nanoparticles: Characterization and Estimation of the Cellular Toxicity against Breast Cancer Cell Line (MCF-7)

“…It has been proved that ceria nanoparticles are effective against oxidative stress and have an antioxidant role. Cerium oxide nanoparticles (nanoceria) are able to mimic the activity of superoxide dismutase and catalase due to changes in oxidation state [37,38]; therefore, these nanoparticles can be used as scavengers for reactive oxygen species (ROS) and inhibitors of the invasion and sensitization of cells to radiotherapy and chemotherapy [39][40][41]. Cerium oxide nanoparticles have cytotoxic effects against cancer cells and can induce apoptosis in them.…”

Bioactive silver phosphate/polyindole nanocomposites

“…9,11,12 H 2 O 2 can exert oxidative stress on biological systems 9 by generating ROS intracellularly. 13 Intracellular ROS can be endogenous (generated naturally by metabolic processes) or exogenous (generated by other species, e.g. nanomaterials).…”