Insights on catalytic mechanism of CeO2 as multiple nanozymes

Abstract

CeO 2 with the reversible Ce 3+ /Ce 4+ redox pair exhibits multiple enzyme-like catalytic performance, which has been recognized as a promising nanozyme with potentials for disease diagnosis and treatments. Tailorable surface physicochemical properties of various CeO 2 catalysts with controllable sizes, morphologies, and surface states enable a rich surface chemistry for their interactions with various molecules and species, thus delivering a wide variety of catalytic behaviors under different conditions. Despite the significant progress made in developing CeO 2 -based nanozymes and their explorations for practical applications, their catalytic activity and specificity are still uncompetitive to their counterparts of natural enzymes under physiological environments. With the attempt to provide the insights on the rational design of highly performed CeO 2 nanozymes, this review focuses on the recent explorations on the catalytic mechanisms of CeO 2 with multiple enzyme-like performance. Given the detailed discussion and proposed perspectives, we hope this review can raise more interest and stimulate more efforts on this multi-disciplinary field.

Nanoceria-Based Artificial Nanozymes: Review of Materials and Applications

“…A few review papers on CeO 2 NMs have been published; 31,32,34−36 the latest one was published in 2022. 37 As we know, the behavior of a nanozyme is determined by the physical and chemical properties. 38 Several concerns must be addressed, or at the very least recognized:…”

Nanocatalytic Biofunctional MOF Coating on Titanium Implants Promotes Osteoporotic Bone Regeneration through Cooperative Pro-osteoblastogenesis MSC Reprogramming

“…Hence, developing biomaterials with antioxidant properties to reprogram MSCs holds considerable promise for repairing osteoporotic bone defects. Interestingly, Ce is a rare-earth element with versatile catalytic functions, which has attracted broad interest for the intervention against osteoporosis-related indications. − Specifically, Ce ion could demonstrate similar catalytic functions like endogenous antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) to mediate the detoxification of ROS, which could contribute to eliminate the oxidative stress in the osteoporotic microenvironment. , Additionally, some studies proved that Sr could promote the CAT/SOD activity and modulate mitochondrial dynamics for enhanced diabetic osseointegration. , Therefore, Ce and Sr ions could be exploited to coordinatively mediate the resurgence of mitochondrial dynamics in MSCs for functional restoration and enhancing osteogenicity. , Nevertheless, despite the therapeutic promise of the rare-earth metal ions, their therapeutic transition into clinics is impeded by the potential short-term and long-term cytotoxic impacts after accidental leakage, thus warranting new Ce/Sr delivery strategies with improved precision, safety, and efficacy.…”

An Atomic Insight into the Confusion on the Activity of Fe3O4 Nanoparticles as Peroxidase Mimetics and Their Comparison with Horseradish Peroxidase

“…Since peroxidase nanozymes catalyze the redox between H 2 O 2 and TMB (Scheme c) like many solid Fenton catalysts, − it is reasonable to adopt m-TOF for their comparison with HRP. The turnover concept of k cat could thus be wrongly borrowed by Yan’s group. ,,, This is because the observed V max for a given peroxidase nanozyme is associated with not only its [ P ] but surface area per particle ( S NP ) and density of active sites per unit surface area ( A ) as formulated below: Since A is a constant for sphere Fe 3 O 4 NPs enclosed by thermodynamically stable (111) surfaces (ca.…”

“…The report of Fe 3 O 4 NPs (>300 nm) with activity higher than HRP could also be attributed to the unfair comparison between their descriptors (i.e., k cat _ P vs k cat _ E ). ,, For example, when [ E ] = [ P ], only 1 Fe site contributes to the V max for each HRP enzyme but ∼3.7 × 10 6 surface Fe sites for that of a 300 nm Fe 3 O 4 NP . The m-TOF considering the number of active sites involved in the reaction should thus be a better descriptor for such comparison. , Taking particulate Fe 3 O 4 nanozymes as an example. One can approach the concentration of surface Fe sites (denoted as [ Fe ]) from their surface area or more precisely via probe-assisted techniques such as temperature-programmed desorption (TPD), infrared (IR), and nuclear magnetic resonance (NMR) often adopted by the catalysis society. − Herein, this [ Fe ] factor for Fe 3 O 4 NPs in the literature was calculated by considering their [ P ], surface area (from 4πr 2 , where r is the radius), and site density of (111) surface (i.e., 12.97 Fe atoms/nm 2 ) for further discussion.…”

“…1 The m-TOF considering the number of active sites involved in the reaction should thus be a better descriptor for such comparison. 23,24 example. One can approach the concentration of surface Fe sites (denoted as [Fe]) from their surface area or more precisely via probe-assisted techniques such as temperatureprogrammed desorption (TPD), infrared (IR), and nuclear magnetic resonance (NMR) often adopted by the catalysis society.…”