ROS-mediated anticancer effects of EGFR-targeted nanoceria

The therapeutic effectiveness of anticancer drugs, including nanomedicines, can be enhanced with active receptor-targeting strategies. Epidermal growth factor receptor (EGFR) is an important cancer biomarker, constitutively expressed in sarcoma patients of different histological types. The present work reports materials and in vitro biomedical analyses of silanized (passive delivery) and/or EGF-functionalized (active delivery) ceria nanorods exhibiting highly defective catalytically active surfaces. The EGFR-targeting efficiency of nanoceria was confirmed by receptor-binding studies. Increased cytotoxicity and reactive oxygen species (ROS) production were observed for EGF-functionalized nanoceria owing to enhanced cellular uptake by HT-1080 fibrosarcoma cells. The uptake was confirmed by TEM and confocal microscopy. Silanized nanoceria demonstrated negligible/minimal cytotoxicity toward healthy MRC-5 cells at 24 and 48 h, whereas this was significant at 72 h owing to a nanoceria accumulation effect. In contrast, considerable cytotoxicity toward the cancer cells was exhibited at all three times points. The ROS generation and associated cytotoxicity were moderated by the equilibrium between catalysis by ceria, generation of cell debris, and blockage of active sites. EGFR-targeting is shown to enhance the uptake levels of nanoceria by cancer cells, subsequently enhancing the overall anticancer activity and therapeutic performance of ceria.

Bacteroid cerium oxide particles promote macrophage polarization to achieve early vascularization and subsequent osseointegration around implants

The establishment of an osseointegration is crucial for the long-term stability and functionality of implant materials, and early angiogenesis is the key to successful osseointegration. However, the bioinertness of titanium implants affects osseointegration, limiting their clinical application. In this study, inspired by the rapid polarization of macrophages following the phagocytosis of bacteria, we developed bacteroid cerium oxide particles; these particles were composed of CeO2 and had a size similar to that of Bacillus (0.5 μ m). These particles were constructed on the implant surfaces using a hydrothermal method. In vitro experiments demonstrated that the particles effectively decreased the reactive oxygen species (ROS) levels in macrophages (RAW264.7). Furthermore, these particles exerted effects on M1 macrophage polarization, enhanced nitric oxide (NO) secretion to promote vascular regeneration, and facilitated rapid macrophage transition to the M2 phenotype. Subsequently, the particles facilitated human umbilical vein endothelial cell (HUVEC) migration. In vivo studies showed that these particles rapidly stimulated innate immune responses in animal models, leading to enhanced angiogenesis around the implant and improved osseointegration. In summary, the presence of bacteroid cerium oxide particles on the implant surface regulated and accelerated macrophage polarization, thereby enhancing angiogenesis during the immune response and improving peri-implant osseointegration.

Selective inhibition of partial EMT-induced tumour cell growth by cerium valence states of extracellular ceria nanoparticles for anticancer treatment

Targeting specific tumour cells and their microenvironments is essential for enhancing the efficacy of chemotherapy and reducing its side effects. A partial epithelial-to-mesenchymal transition state (pEMT, with a hybrid epithelial/mesenchymal phenotype) in tumour cells is an attractive targeting for anticancer treatment because it potentially provides maximal stemness and metastasis relevant to malignant cancer stem cell-like features. However, treatment strategies to target pEMT in tumour cells remain a challenge. This study demonstrates that extracellular cerium oxide nanoparticles (CNPs) selectively inhibit the growth of pEMT-induced tumour cells, without affecting full epithelial tumour cells. Herein, highly concentrated Ce3+ and Ce4+ ions are formed on CNP-layered poly-L-lactic acid surfaces. Cell cultures of pEMT-induced and uninduced lung cancer cell lines on the CNP-layered substrates allow the effect of extracellular CNPs on tumour cell growth to be investigated. The extracellular CNPs with dominant Ce3+ and Ce4+ ions were able to trap pEMT-induced tumour cells in a growth-arrested quiescent/dormant or cytostatic state without generating redox-related reactive oxygen species (ROS), i.e. non-redox mechanisms. The dominant Ce3+ state provided highly efficient growth inhibition of the pEMT-induced tumour cells. In contrast, the dominant Ce4+ state showed highly selective and appropriate growth regulation of normal and tumour cells, including a mesenchymal phenotype. Furthermore, Ce4+-CNPs readily adsorbed serum-derived fibronectin and laminin. Cerium valence-specific proteins adsorbed on CNPs may influence receptor-mediated cell-CNP interactions, leading to tumour cell growth inhibition. These findings provide new perspectives for pEMT-targeting anticancer treatments based on the unique biointerface of extracellular CNPs with different Ce valence states.

Microneedles loaded with cerium-manganese oxide nanoparticles for targeting macrophages in the treatment of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a prevalent inflammatory autoimmune disease characterised by persistent inflammation and joint damage with elevated levels of reactive oxygen species (ROS). Current treatment modalities for RA have significant limitations, including poor bioavailability, severe side effects, and inadequate targeting of inflamed joints. Herein, we synthesised cerium/manganese oxide nanoparticles (NPs) as efficient drug carriers with antioxidant and catalytic-like functions that can eliminate ROS to facilitate the polarization of macrophages phenotype from M1 to M2 and alleviate inflammation. Methotrexate (MTX), a first-line RA medication, was loaded into the NPs, which were further modified with bovine serum albumin (BSA) and integrated into dissolving hyaluronic acid-based microneedles (MNs) for transdermal delivery.

RESULT

This innovative approach significantly enhanced drug delivery efficiency, reduced RA inflammation, and successfully modulated macrophage polarization toward an anti-inflammatory phenotype.

CONCLUSION

This research not only presents a promising drug delivery strategy for RA but also contributes broadly to the field of immune disease treatment by offering an advanced approach for macrophage phenotypic reprogramming.

Solanum tuberosum tuber-driven starch-mediated green-hydrothermal synthesis of cerium oxide nanoparticles for efficient photocatalysis and antimicrobial activities

In this study, we are reporting for the first time the utilization of Solanum tuberosum tuber-driven, starch-mediated, green-hydrothermally synthesized cerium oxide nanoparticles (G-CeO2 NPs) for the antibacterial activity and photodegradation of cationic (methylene blue, MB) and anionic (methyl orange, MO) dyes separately and in combination, aimed at environmental remediation. The XRD analysis confirms the fluorite structure of G-CeO2 NPs, displaying an average crystallite size of 9.6 nm. Further, XPS confirms the existence of 24% of Ce3+ oxidation states within G-CeO2 NPs. Morphological studies through FE-SEM and TEM reveal that starch-driven OH- ion production leads to a high percentage of active crystal facets, favoring the formation of Ce3+-rich CeO2 NPs. Photocatalytic experiments conducted under UV-A illumination demonstrate the superior degradation performance of G-CeO2 NPs, with MB degradation reaching 93.4% and MO degradation at 77.2% within 90 min. This outstanding catalytic activity is attributed to the mesoporous structure (pore diameter of 5.63 nm) with a narrow band gap, a large surface area (103.38 m2g-1), and reduced charge recombination, as validated by BET, UV-visible, and electrochemical investigations. The identification of photogenerated intermediates is achieved through LCMS, while the mineralization is monitored via total organic carbon analysis. Moreover, the scavenging experiments point towards the involvement of reactive oxygen species in organic oxidation, demonstrating efficiency over five consecutive trials. Additionally, G-CeO2 NPs exhibit potent antibacterial activity against both gram-positive and gram-negative bacteria. This study presents an innovative, and efficient approach to environmental remediation, shedding light on the potential of G-CeO2 NPs in addressing environmental pollution challenges.

CeO2 Nanoparticles to Promote Wound Healing: A Systematic Review

Cerium (Ce) is a hot topic in the field of materials research due to its electronic layer structure and the unique antioxidant abilities of its oxide (CeO2 ). Cerium oxide nanoparticles (CeO2 NPs) demonstrate their potential as an antioxidant and antibacterial agent. Current research focuses on whether they can be used to promote wound healing and in what manner. This article provides a systematic review of the various forms of CeO2 NPs that are used in wound-healing materials over the past decade, as well as the effectiveness demonstrated by in vivo and in vitro experiments, with a focus on the relationship between concentration and effectiveness. CeO2 NPs are expected to become effective ingredients in dressings that require antibacterial, antioxidant, and wound healing promoting properties. This article serves as a reference for further research and clinical applications of nano-sized CeO2 in wound healing.

Cerium-Luteolin Nanocomplexes in Managing Inflammation-Related Diseases by Antioxidant and Immunoregulation

Oxidative stress, characterized by an imbalance between reactive oxygen species (ROS) production and the antioxidant defense system, plays a pivotal role in inflammation-related diseases. Excessive ROS levels can induce cellular damage and impair normal physiological functions, triggering the release of inflammatory mediators and exacerbating the inflammatory response, ultimately leading to irreversible tissue damage. In this study, we synthesized cerium ion-luteolin nanocomplexes (CeLutNCs) by coordinating Ce ions with the natural product luteolin, aiming to develop a therapeutic agent with excellent antioxidant and immunoregulation properties for ROS-related inflammation treatment. In vitro experiments demonstrated that the prepared CeLutNCs effectively scavenged excess ROS, prevented cell apoptosis, down-regulated levels of important inflammatory cytokines, regulated the response of inflammatory macrophages, and suppressed the activation of the nuclear factor-κ-gene binding (NF-κB) pathway. In an acute kidney injury (AKI) animal model, CeLutNCs exhibited significant efficacy in improving kidney function, repairing damaged renal tissue, and reducing oxidative stress, inflammatory response, and cellular apoptosis. Moreover, the therapeutic potential of CeLutNCs in an acute lung injury (ALI) model was confirmed through the assessment of inflammatory responses and histopathological studies. This study emphasizes the effectiveness of these metal-natural product coordination nanocomplexes as a promising therapeutic approach for preventing AKI and other diseases associated with oxidative stress.

A novel isatin Schiff based cerium complex: synthesis, characterization, antimicrobial activity and molecular docking studies

In this work, a novel isatin-Schiff base L2 had been synthesized through a simple reaction between isatin and 2-amino-5-methylthio-1,3,4-thiadiazole. The produced Schiff base L2 was then subjected to a hydrothermal reaction with cerium chloride to produce the cerium (III)-Schiff base complex C2. Several spectroscopic methods, including mass spectra, FT-IR, elemental analysis, UV-vis, 13C-NMR, 1H-NMR, Thermogravimetric Analysis, HR-TEM, and FE-SEM/EDX, were used to completely characterize the produced L2 and C2. A computer simulation was performed using the MOE software program to find out the probable biological resistance of studied compounds against the proteins in some types of bacteria or fungi. To investigate the interaction between the ligand and its complex, we conducted molecular docking simulations using the molecular operating environment (MOE). The docking simulation findings revealed that the complex displayed greater efficacy and demonstrated a stronger affinity for Avr2 effector protein from the fungal plant pathogen Fusarium oxysporum (code 5OD4) than the original ligand. The antibacterial activity of the ligand and its Ce3+ complex were applied in vitro tests against different microorganism. The study showed that the complex was found to be more effective than the ligand.

Biomedical applications of cerium vanadate nanoparticles: a review

Cerium vanadate nanoparticles (CeVO4 NPs), which are members of the rare earth orthovanadate nanomaterial family, have generated considerable interest due to their diverse properties and prospective biomedical applications. The current study, which provides a comprehensive overview of the synthesis and characterization techniques for CeVO4 NPs, emphasizes the sonochemical method as an efficient and straightforward technique for producing CeVO4 NPs with tunable size and shape. This paper investigates the toxicity and biocompatibility of CeVO4 NPs, as well as their antioxidant and catalytic properties, which allow them to modify the redox state of biological systems and degrade organic pollutants. In addition, the most recent developments in the medicinal applications of CeVO4 NPs, such as cancer treatment, antibacterial activity, biosensing, and drug or gene delivery, are emphasized. In addition, the disadvantages of CeVO4 NPs, such as stability, aggregation, biodistribution, and biodegradation, are outlined, and several potential solutions are suggested. The research concludes with data and recommendations for developing and enhancing CeVO4 NPs in the biomedical industry.

Effect of Ag and Ni-Doped Cerium Oxide Nanoparticles on the Formation of ROS and Evaluation as an Alternative Physical Sunscreen Material

CeO2 nanoparticles (nanoceria) were proposed as an alternative physical sunscreen agent with antioxidant properties and comparable UV absorption performance. Green synthesis of nanoceria with Ag and Ni dopants resulted in doped nanoceria with lower catalytic activity and biologically-safe characteristics. The doped nanoceria was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Rancimat Instrument, and UV-Vis Spectrophotometer for SPF (Sun Protection Factor) determination. XRD and TEM analysis showed that nanoceria had been successfully formed in nanoscale-sized with a change in crystallite size due to the crystal defect phenomenon caused by dopant addition. While the Rancimat test and band gap energy analysis were conducted to evaluate the oxidative stability and reactive oxygen species formation, it was confirmed that dopant addition could decrease catalytic activity of material, resulting in Ni-doped Ce with a longer incubation time (11.81 h) than Ag-doped Ce (10.58 h) and non-doped Ce (10.30 h). In-vitro SPF value was measured using the thin layer technique of sunscreen prototype with Virgin Coconut Oil (VCO)-based emulsion, which yielded 10.862 and 5.728 SPF values for 10% Ag-doped Ce and 10% Ni-doped Ce, respectively. The dopant addition of nanoceria could reduce catalytic activity and give a decent in vitro UV-shielding performance test; thus, Ag and Ni-doped nanoceria could be seen as promising candidates for alternative physical sunscreen agents.

Effects of cerium-doped bioactive glass incorporation on an alginate/gelatin scaffold for bone tissue engineering: In vitro characterizations

Bioactive glasses (BGs) have been extensively employed in treating bone defects due to their capacity to bond and integrate with hard and soft tissues. To promote their characteristics, BGs are doped with therapeutic inorganic ions; Among these, Cerium (Ce) is of special attention because of its material and biological properties. This study aimed to investigate the effects of the addition of Ce to BG on the physicochemical and biological properties of the alginate/gelatin (Alg-Gel) scaffold compared with a similar scaffold that only contains BG45S5. The scaffolds were characterized for their biocompatibility using human bone marrow-derived mesenchymal stem cells (hBM-MSCs) by MTT analysis. The osteogenic differentiation of hBM-MSCs cultured on the scaffolds was assessed by evaluating the alkaline phosphatase (ALP) activity and the expression of osteogenic-related genes. Scanning electron microscopy of the prepared scaffolds showed an interconnected porous structure with an average diameter of 212-272 μm. The Young's modulus of the scaffolds significantly increased from 13 ± 0.82 MPa for Alg-Gel to 91 ± 1.76 MPa for Alg-Gel-BG/Ce. Ce doping improved the osteogenic differentiation of hBM-MSCs and ALP secretion compared to the other samples, even without adding an osteogenic differentiation medium. The obtained results demonstrated the biocompatibility and osteo-inductive potentials of the Alg-Gel-BG/Ce scaffold for bone tissue engineering.

Neurological study on the effect of CeNPs and/or La Cl3 on adult male albino rats

Lanthanides are a group of 15 elements (8 heavy and 7 light) grouped for their proximity in the chemical and physical properties. Recently, this group of elements has received great attention because of their importance, and their entrance into many industrial technologies making the probability of the living organisms' exposure to it increase. The present study aims to study ability of cerium nanoparticles (CeNPs) or lanthanum (LaCl3) to cross the blood brain barrier also, investigate their neuro effect separately or together on some parameters in six brain areas (cortex, cerebellum, hippocampus, striatum, midbrain, and hypothalamus) of the adult male albino rats. The results showed the ability of both elements to distribute and accumulate in the different brain areas. Also, the results of CeNPs or LaCl3 treatment were in the same line where each element caused a significant decrease in norepinephrine (NE), dopamine (DA), serotonin (5-HT) and GABA accompanied with a significant increase in 5- hydroxyl indoleacetic acid (5-HIAA) glucose level. On the other hand, GSH and MDA showed a significant decrease after CeNPs treatment while, with LaCl3 treatment, MDA showed a significant increase in the different brain areas after 3 weeks of treatment. The coadministration of CeNPs and La Cl3 caused an ameliorating effect in all the tested parameters. In conclusion, from the previous studies the effects of lanthanides in the present study may be in part due to its effect on the release or turnover of neurotransmitters and insulin secretion. Finally, the ameliorative effect of CeNPs may be regarded as its high activity to scavenge the free radicals.

Remineralization of Dentin with Cerium Oxide and Its Potential Use for Root Canal Disinfection

Objective

This study was to investigate a novel antibacterial biomimetic mineralization strategy for exploring its potential application for root canal disinfection when stabilized cerium oxide was used.

Material and Methods

A biomimetic mineralization solution (BMS) consisting of cerium nitrate and dextran was prepared. Single-layer collagen fibrils, collagen membranes, demineralized dentin, and root canal system were treated with the BMS for mineralization. The mineralized samples underwent comprehensive characterization using various techniques, including transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared spectroscopy (FTIR), scanning transmission electron microscopy (STEM), selected-area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and micro-CT. Additionally, the antimicrobial properties of the BMS and the remineralized dentin were also analyzed with broth microdilution method, live/dead staining, and SEM.

Results

Cerium ions in the BMS underwent a transformation into cerium oxide nanoparticles, which were deposited in the inter- and intra-fibrillar collagen spaces through a meticulous bottom-up process. XPS analysis disclosed the presence of both Ce (III) and Ce (IV) of the generated cerium oxides. A comprehensive examination utilizing SEM and micro-CT identified the presence of cerium oxide nanoparticles deposited within the dentinal tubules and lateral canals of the root canal system. The BMS and remineralized dentin exhibited substantial antibacterial efficacy against E. faecalis, as substantiated by assessments involving the broth dilution method and live/dead staining technique. The SEM findings revealed the cell morphological changes of deceased E. faecalis.

Conclusion

This study successfully demonstrated antibacterial biomimetic mineralization as well as sealing dentinal tubules and lateral branches of root canals using cerium nitrate and dextran. This novel biomimetic mineralization could be used as an alternative strategy for root canal disinfection.

Albumin Retains Its Transport Function after Interaction with Cerium Dioxide Nanoparticles

The interaction of inorganic nanomaterials with biological fluids containing proteins can lead not only to the formation of a protein corona and thereby to a change in the biological activity of nanoparticles but also to a significant effect on the structural and functional properties of the biomolecules themselves. This work studied the interaction of nanoscale CeO2, the most versatile nanozyme, with human serum albumin (HSA). Fourier transform infrared spectroscopy, MALDI-TOF mass spectrometry, UV-vis spectroscopy, and fluorescence spectroscopy confirmed the formation of HSA-CeO2 nanoparticle conjugates. Changes in protein conformation, which depend on the concentration of both citrate-stabilized CeO2 nanoparticles and pristine CeO2 nanoparticles, did not affect albumin drug-binding sites and, accordingly, did not impair the HSA transport function. The results obtained shed light on the biological consequences of the CeO2 nanoparticles' entrance into the body, which should be taken into account when engineering nanobiomaterials to increase their efficiency and reduce the side effects.

N-Acetyl cysteine amide and cerium oxide nanoparticles as a drug delivery for ischemic stroke treatment: Inflammation and oxidative stress crosstalk

BACKGROUND

Inflammation and oxidative stress crosstalk is involved in the ischemic stroke(IS) pathogenesis and the new therapeutic options should be offered based on the targets that are critical in the golden hour of IS. YKL-40 and total antioxidant capacity(TAC), the inflammation and oxidative stress biomarkers, provide us with clues for proper intervention targets. N-acetyl cysteine amide (NACA), a lipophilic antioxidant, with a nanoparticle-based drug delivery system is permeable enough to penetrate blood-brain barrier (BBB) and was proposed as a new treatment option for IS. In this study, we evaluated the YKL-40 and TAC levels in the sera of IS patients to elucidate the best intervention target. A rat tissue model is used to assess the NACA efficiency. The microbiology tests performed to figure out the potential NACA and antibiotics interactions.

MATERIAL AND METHODS

The YKL-40 and TAC were measured in the serum of IS patients by ELISA and FRAP methods, respectively. The serum samples were obtained 12 h after the patient's admission and meantime other laboratory findings and NIHSS-based prognosis were recorded. In the animal study, the brain cortex, liver, kidney, adipose, and the heart of healthy rats were dissected and then incubated in DMEM cell culture media containing 50 micrograms/milliliter of nanoparticles; the nanoparticles were titanium dioxide nanoparticles (TiO2 NPs), copper oxide nanoparticles (CuO NPs) and cerium dioxide nanoparticles (CeO2 NPs). Olive oil and human serum albumin solution were exposed to the nanoparticles with and without NACA. TAC was measured in the supernatant culture media. With similar concentrations and settings, we evaluated the NACA, nanoparticle, and antibiotics interactions on pseudomonas aeruginosa.

RESULTS

There was a nonparametric correlation between YKL-40 levels and post stroke serum TAC levels. Nonsmokers had higher YKL-40 and TAC levels than smokers. A new calculated variable, urea*lymphocyte/age, predicts a poor prognosis with an acceptable AUC (0.708). Exposing to the nanoparticles, the liver, kidney, and brain had a significantly higher TAC than adipose and cardiac tissue. The NACA had an ameliorative effect against TiO2 NPs in the brain. This effectiveness of NACA was also observed against CuO NPs treatment. However, the CeO2 NPs exert a strong antioxidant property by reducing the TAC in the brain tissue but not the others. Albumin showed antioxidant properties by itself, but olive oil had an inert behavior. NACA had no interaction with the action of routine antibiotics.

CONCLUSION

Oxidative stress but not inflammation is the best point for intervention in IS patients because YKL-40 has not a relationship with NIHSS score. The CeO2 NPs and NACA combination are eligible option to develop antioxidant-based drug for the treatment of IS. As a complementary finding, the urea*lymphocyte/age is proposed as a NIHSS-based prognosis biomarker.

Nano cerium oxide and cerium/zinc nanocomposites characterization and therapeutic role in combating obesity via controlling oxidative stress and insulin resistance in rat model

BACKGROUND

CeO2NPs and ZnONPs can curb the increase of cholesterol and triglycerides observed in rats with non-alcoholic fatty liver disease. It was suggested that CeO2 NPs could potentially have an insulin-sensitizing effect, specifically on adipose tissue and skeletal muscle. It was reported that ZnONPs combat the increase of insulin resistance observed in obese rats and could be beneficial value in NAFLD. In our previous work, ZnO-NPs manifested valuable anti-obesity effects via lowering body weight gain, oxidative stress, BMI, lipids, and insulin resistance.

METHODS

In the present study, cerium oxide nanoparticles (A-1) and cerium/zinc nanocomposites (A-2 and A-3) were synthesized by solgel to investigate their role on oxidative stress, adipocyte hormones, and insulin resistance in an obese rat model. X-ray diffraction, HRTEM, SEM, and XPS were carried out to confirm the crystal structure, the particle size, the morphology of the nanoparticles and the oxidation states.

RESULTS

The Rietveld refinement has also been executed on A-1 (chi2 = 1.00; average Bragg = 2.92%; R-factor = 2.45%) and on A-2 (Rw = 9.87%, Rex= 9.68%, χ2 = 1.04, GoF = 1.02). The XPS spectra indicated the presence of Ce in + 4 and + 3 oxidation states and Zn as ZnO and ZnO.OH. Cerium oxide and ZnO crystal sizes lie in the range 40.53-45.01 and 40.53-45.01 nm, respectively. The results indicated that treating obese rats with any of the tested nano compounds (5 mg or 10 mg/Kg) lowered plasma cholesterol, triglycerides, LDL, insulin resistance, glucose, and BMI significantly relative to obese group values. On the other hand, HDL increased significantly in obese rats after treatment with either A-2 or A-3 compared to obese rats. The current investigation showed antioxidant activities for A-1, A-2, and A3 as evidenced by the significant increase in GSH level and a significant decrease in MDA.

CONCLUSION

It was found that A-1, A-2, and A-3 have an efficient therapeutic role in treating of obesity-related hyperlipidemia, oxidative stress and insulin resistance. The results of A-2 and A-3 were more pronounced than those of A-1. The use of Zn/Ce nanocomposite (that have positive characteristics) in combating obesity and its complications could be become a new trend in therapeutic application for a management of obesity.

In vitro analyses of cerium oxide nanoparticles in degrading anthracene/fluorene and revealing the antibiofilm activity against bacteria and fungi

A sol-gel method was used to synthesize the cerium dioxide nanoparticles. The nanoparticles formed were then characterized with UV-visible spectrophotometry, Fourier Transform Infrared Spectrophotometer (FTIR), SEM-EDAX, XRD, and Dynamic Light Scattering (DLS). The UV-visible absorbance at 282 nm and characteristic peak at 600-4000 cm-1 provided insight into the formation of cerium dioxide nanoparticles using a chemical method. SEM analysis and EDAX analysis confirmed nanoparticle formation and elements within the nanoparticles based on their irregular morphology. The hydrodynamic size obtained from the DLS analysis was 178.4 nm and the polydispersity was 0.275 nm. Furthermore, XRD results confirmed the crystalline nature of cerium dioxide nanoparticles. Using batch adsorption as a method, the effect of concentration of Polycyclic Aromatic Hydrocarbons (PAH), adsorbent concentration, pH, and irradiation source was investigated. Under UV light conditions, 10 μg/mL cerium dioxide nanoparticle at pH 5 degraded 2 μg/mL of PAH (anthracene and fluorene). Consequently, the synthesized cerium dioxide nanoparticles were effective photocatalysts. For anthracene and fluorene, kinetic studies showed the degradation process followed pseudo-second-order kinetics and Freundlich isotherms. Cerium oxide also exhibited significant antimicrobial and antibiofilm activity against bacteria and fungi. As a result, the cerium dioxide nanoparticle has proved to be a highly effective photocatalytic tool for the degradation of PAHs and exhibits strong antimicrobial activity.

Green synthesis of zinc and nickel dual-doped cerium oxide nanoparticles: antioxidant activity and cytotoxicity effects

Cerium oxide nanoparticles (CeO2-NPs) and Zn-Ni dual-doped CeO2-NPs were synthesized through a green approach by the implication of zucchini peel (Cucurbita pepo) extract as a capping and reduction agent. All the synthesized samples were studied by the results of FTIR, UV-Vis, XRD, and FESEM/EDAX/PSA analyses. The Zn-Ni dual-doped CeO2-NPs contained a spherical morphology and their size was observed to increase at higher temperatures. The conducted MTT assay on the Huh-7 cell line displayed 50% of cells annihilation as a result of using undoped CeO2-NPs and Zn-Ni dual-doped CeO2-NPs at the inhibitory concentrations (IC50) of 700 and 185.4 μg/mL, respectively. We also evaluated the enzymatic functionality of SOD and CAT of undoped CeO2-NPs and dual-doped NPs and found it to be dose dependent. Moreover, Zn-Ni dual-doped CeO2-NPs intensified the CAT activity without causing any changes in SOD activity in similar concentrations.

ATP-triggered, selective superoxide radical generating oxidase-mimetic cerium oxide nanozyme exhibiting efficient antibacterial activity at physiological pH

Bacterial infections are considered as one of the major health threats to the global population. The advent of bacterial species with antibiotic resistance has attracted significant efforts to develop novel materials and strategies to effectively avoid the resistance with enhanced antibacterial potential. In this work, we have developed oxidase-mimetic cerium oxide nanoparticles (CeO2 NPs), which exhibit nanozyme activity at physiological pH in the presence of adenosine triphosphate (ATP). The oxidase-mimetic activity was confirmed to involve superoxide radicals using p-benzoquinone and dihydroethidium. Using indole propionic acid, ethanol, and terephthalic acid, it was confirmed that the oxidase-mimetic activity of CeO2 NPs with ATP does not involve the formation of hydroxyl radicals. CeO2 NPs with ATP produced a strong antibacterial activity against Staphylococcus aureus and Escherichia coli within 3 - 6 hrs. The bacterial cell morphology analysis suggested that superoxide radicals generated during the oxidase-mimetic activity of CeO2 NPs with ATP cause distortion of paired and tetrad arrangement (Staphylococcus aureus), loss of cytoplasmic content, damage, and pore formation in the cell wall (Escherichia coli) that led to the death of bacteria. Further, the live/dead assay also concludes the time-dependent death of bacterial cells with the highest death in the cell population exposed to CeO2 NPs and ATP. Thus, the antibacterial activity at physiological pH by superoxide radical generating oxidase-mimetic CeO2 NPs could be further extended to other pathogenic bacterial species.

Effectiveness of Cerium Oxide Nanoparticles in Non-Alcoholic Fatty Liver Disease Evolution Using In Vivo and In Vitro Studies: A Systematic Review

Nonalcoholic fatty liver disease (NAFLD) describes a spectrum of liver abnormalities, from benign steatosis to nonalcoholic steatohepatitis (NASH). Because of their antioxidant capabilities, CeNPs have sparked a lot of interest in biological applications. This review evaluated the effectiveness of CeNPs in NAFLD evolution through in vivo and in vitro studies. Databases such as MEDLINE, EMBASE, Scopus, and Web of Science were looked for studies published between 2012 and June 2023. Quality was evaluated using PRISMA guidelines. We looked at a total of nine primary studies in English carried out using healthy participants or HepG2 or LX2 cells. Quantitative data such as blood chemical markers, lipid peroxidation, and oxidative status were obtained from the studies. Our findings indicate that NPs are a possible option to make medications safer and more effective. In fact, CeNPs have been demonstrated to decrease total saturated fatty acids and foam cell production (steatosis), reactive oxygen species production and TNF-α (necrosis), and vacuolization in hepatic tissue when used to treat NAFLD. Thus, CeNP treatment may be considered promising for liver illnesses. However, limitations such as the variation in durations between studies and the utilization of diverse models to elucidate the etiology of NAFLD must be considered. Future studies must include standardized NAFLD models.

Calcein-Modified CeO2 for Intracellular ROS Detection: Mechanisms of Action and Cytotoxicity Analysis In Vitro

Cerium oxide nanoparticles (CeO2 NPs) are metal-oxide-based nanozymes with unique reactive oxygen species (ROS) scavenging abilities. Here, we studied new CeO2 NPs modified with calcein (CeO2-calcein) as an intracellular ROS inactivation/visualization theranostic agent. The molecular mechanisms of the CeO2-calcein intracellular activity, allowing for the direct monitoring of ROS inactivation in living cells, were studied. CeO2-calcein was taken up by both normal (human mesenchymal stem cells, hMSc) and cancer (human osteosarcoma, MNNG/Hos cell line) cells, and was easily decomposed via endogenous or exogenous ROS, releasing brightly fluorescent calcein, which could be quantitatively detected using fluorescence microscopy. It was shown that the CeO2-calcein has selective cytotoxicity, inducing the death of human osteosarcoma cells and modulating the expression of key genes responsible for cell redox status as well as proliferative and migration activity. Such cerium-based theranostic agents can be used in various biomedical applications.

Cerium oxide nanoparticles alleviates stress in wheat grown on Cd contaminated alkaline soil

The cadmium contamination of soil is an alarming issue worldwide and among various mitigation strategies, nanotechnology mediated management of Cd contamination has become a well-accepted approach. The Cerium Oxide Nanoparticles (CeO2-NPs) are widely being explored for their novel works in Agro-Industry and Environment, including stress mitigation in crops. Very little work is reported regarding role of CeO2-NPs in management of Cd contamination in cereal crops like wheat. Present work was planned to check efficacy of CeO2-NPs in Cd stress mitigation of wheat under alkaline calcareous soil conditions. In this experiment, 4 sets of Cd contamination (Uncontaminated control-UCC, 10, 20, and 30 mg Cd per kg soil) and 5 sets of CeO2-NPs NPs (0, 200, 400, 600, and 1000 mg NP per kg soil) were applied in pots following completely randomized design (CRD) and wheat crop was grown. The growth, physiology, yield and Cd and Ce accumulation by wheat root, shoot and grain was monitored. The maximum Cd spiking level (30 mg kg-1) was found to be most toxic for plant growth. The results showed that the nanoparticles were overall beneficial for wheat growth and maximum level (1000 mg kg-1) being the most significant one under all Cd spiking sets. In Cd-30 sets, 1000 mg kg-1 NPs application resulted in decreased soil bioavailable Cd concentration (49.63% decrease compared to 30 mg kg-1 Cd spiked sets termed as Cd-30 Control), decreased Cd accumulation in all three tissues: root (58.36% decrease), shoot (52.30% decrease) and grain (55.56% decrease) while increased root dry weight (62.14%), shoot dry weight (89.32%), total grain yield (80.08%) and improved plant physiology with respect to Cd-30 control. Nanoparticles application substantially increased wheat root, shoot and grain Ce concentrations as well. The further prospects of these nanoparticles in relation to various biotic and abiotic stresses are advised to be explored.

Effect of green synthesized cerium oxide nanoparticles on fungal disease of wheat plants: A field study

Recently, there has been considerable attention towards the production of environmentally friendly nanoparticles (NPs). In this investigation, the successful synthesis of cerium oxide nanoparticles (CeO2 NPs) was achieved by employing an eco-friendly technique that utilized an extract from the leaves of local plant quinoa (Chenopodium quinoa L.). The synthesized CeO2 NPs were subjected to characterization using state-of-the-art methods. The prepared CeO2 NPs contained a round shape with clusters and have a size of 7-10 nm. To assess how effective CeO2 NPs derived from C. quinoa were against Ustilago tritici, a fungal disease that negatively affects wheat crop globally, a study was performed on two varieties of wheat crop comprised of Arooj (V1) and Akber (V2), cultivated under field conditions. CeO2 NPs were applied foliarly twice to the wheat crop at four different concentrations: T0 (0 mg/L), T1 (50 mg/L), T2 (75 mg/L), and T3 (100 mg/L). The results revealed that the control group (T0) exhibited the highest disease severity index (DSI) with a value of 75% compared to the other concentrations of CeO2 NPs on both varieties. At a concentration of 100 mg/L of CeO2 NPs, the DSI dropped to a minimum of 35% and 37% on both V1 and V2 respectively. These findings indicated that an increase in the concentration of CeO2 NPs has a beneficial impact on disease severity. Similar patterns have also been observed with disease incidence (DI), with the greatest efficacy observed at a concentration of 100 mg/L of CeO2 NPs. Our investigation has shown that CeO2 NPs exhibitd significant antifungal potential against U. tritici which may be a promising strategy to mitigate fungal disease and crop losses globally.

Influence of the Synthesis Scheme of Nanocrystalline Cerium Oxide and Its Concentration on the Biological Activity of Cells Providing Wound Regeneration

In the ongoing search for practical uses of rare-earth metal nanoparticles, cerium dioxide nanoparticles (nanoceria) have received special attention. The purpose of this research was to study the biomedical effects of nanocrystalline forms of cerium oxide obtained by different synthesis schemes and to evaluate the effect of different concentrations of nanoceria (from 10-2 to 10-6 M) on cells involved in the regeneration of skin cell structures such as fibroblasts, mesenchymal stem cells, and keratinocytes. Two different methods of nanoceria preparation were investigated: (1) CeO-NPs-1 by precipitation from aqueous solutions of cerium (III) nitrate hexahydrate and citric acid and (2) CeO-NPs-2 by hydrolysis of ammonium hexanitratocerate (IV) under conditions of thermal autoclaving. According to the X-ray diffraction, transmission electron microscopy, and dynamic light scattering data, CeO2-1 consists of individual particles of cerium dioxide (3-5 nm) and their aggregates with diameters of 60-130 nm. CeO2-2 comprises small aggregates of 8-20 nm in diameter, which consist of particles of 2-3 nm in size. Cell cultures of human fibroblasts, human mesenchymal stem cells, and human keratinocytes were cocultured with different concentrations of nanoceria sols (10-2, 10-3, 10-4, 10-5, and 10-6 mol/L). The metabolic activity of all cell types was investigated by MTT test after 48 and 72 h, whereas proliferative activity and cytotoxicity were determined by quantitative cell culture counting and live/dead test. A dependence of biological effects on the method of nanoceria preparation and concentration was revealed. Data were obtained with respect to the optimal concentration of sol to achieve the highest metabolic effect in the used cell cultures. Hypotheses about the mechanisms of the obtained effects and the structure of a fundamentally new medical device for accelerated healing of skin wounds were formulated. The method of nanoceria synthesis and concentration fundamentally and significantly change the biological activity of cell cultures of different types-from suppression to pronounced stimulation. The best biological activity of cell cultures was determined through cocultivation with sols of citrate nanoceria (CeO-NPs-1) at a concentration of 10-3-10-4 M.

Multifunctional Hyaluronic Acid Microneedle Patch Embedded by Cerium/Zinc-Based Composites for Accelerating Diabetes Wound Healing

Chronic nonhealing diabetic wounds are becoming increasingly severe, with high rates of mortality and disability, owing to the difficulty in wound healing caused by hyperglycemia, blocked angiogenesis, biofilm infection, and excessive oxidative stress. A multicomponent enzyme-responsive natural polymer, a hyaluronic acid (HA) microneedle, embedded in a cerium/zinc-based nanomaterial (ZCO) for the treatment of diabetic wounds is reported. ZCO-HA can destroy the oxidation balance of bacteria, kill bacteria, and scavenge reactive oxygen species (ROS) to alleviate oxidative stress via the adjustable release of Zn2+ and Ce3+ /4+ . Additionally, ZCO-HA exhibits good anti-inflammatory activity through the nuclear factor kappa-B (NF-κB) pathway, which reduces the inflammatory state of macrophages and promotes cell proliferation, migration, and angiogenesis. In vitro experiments shows that ZCO-HA accompanies mouse fibroblast migration, promoting human umbilical vein endothelial cell tube formation. In vivo studies in mice with streptozotocin-induced (STZ)-induced diabetes reveal that this microneedle accelerates wound healing without systemic toxicity. RNA transcriptome sequencing illustrates that the multicomponent HA microneedle accelerates wound healing in diabetes through cell migration and inhibits inflammatory reactions and oxidative damage in mice via the NF-κB signaling pathway.

Zinc/Cerium-Substituted Magnetite Nanoparticles for Biomedical Applications

Numerous studies have reported the possibility of enhancing the properties of materials by incorporating foreign elements within their crystal lattice. In this context, while magnetite has widely known properties that have been used for various biomedical applications, the introduction of other metals within its structure could prospectively enhance its effectiveness. Specifically, zinc and cerium have demonstrated their biomedical potential through significant antioxidant, anticancer, and antimicrobial features. Therefore, the aim of the present study was to develop a series of zinc and/or cerium-substituted magnetite nanoparticles that could further be used in the medical sector. The nanostructures were synthesized through the co-precipitation method and their morpho-structural characteristics were evaluated through X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) analyses. Furthermore, the nanostructures were subjected to a ROS-Glo H2O2 assay for assessing their antioxidant potential, MTT assay for determining their anticancer effects, and antimicrobial testing against S. aureus, P. aeruginosa, and C. albicans strains. Results have proven promising for future biomedical applications, as the nanostructures inhibit oxidative stress in normal cells, with between two- and three-fold reduction and cell proliferation in tumor cells; a two-fold decrease in cell viability and microbial growth; an inhibition zone diameter of 4–6 mm and minimum inhibitory concentration (MIC) of 1–2 mg/mL.

Foliar application of nanoceria attenuated cadmium stress in okra (Abelmoschus esculentus L.)

Foliar application of nanoparticles (NPs) as a means for ameliorating abiotic stress is increasingly employed in crop production. In this study, the potential of CeO₂-NPs as stress suppressants for cadmium (Cd)-stressed okra (Abelmoschus esculentus) plants was investigated, using two cycles of foliar application of CeO₂-NPs at 200, 400, and 600 mg/l. Compared to untreated stressed plants, Cd-stressed plants treated with CeO₂-NPs presented higher pigments (chlorophyll a and carotenoids). In contrast, foliar applications did not alter Cd root uptake and leaf bioaccumulation. Foliar CeO₂-NPs application modulated stress enzymes (APX, SOD, and GPx) in both roots and leaves of Cd-stressed plants, and led to decreases in Cd toxicity in plant's tissues. In addition, foliar application of CeO₂-NPs in Cd-stressed okra plants decreased fruit Cd contents, and improved fruit mineral elements and bioactive compounds. The infrared spectroscopic analysis of fruit tissues showed that foliar-applied CeO₂-NPs treatments did not induce chemical changes but induced conformational changes in fruit macromolecules. Additionally, CeO₂-NPs applications did not alter the eating quality indicator (Mg/K ratio) of okra fruits. Conclusively, the present study demonstrated that foliar application of CeO₂-NPs has the potential to ameliorate Cd toxicity in tissues and improve fruits of okra plants.

Effects of CeO2 Nanoparticles on Nutritional Quality of Two Crop Plants, Corn (Zea mays L.) and Soybean (Glycine max L.)

With the widespread applications of manufactured nanoparticles (NPs), there are increasing concerns about their potential adverse effects on the environment and living systems. Many studies demonstrated that NPs could significantly affect the growth and development of crop plants. However, knowledge regarding the impacts of NPs on crop quality is rather limited. In this study, the effects of CeO₂ NPs (25, 75, and 225 mg Ce/kg) and CeCl₃ (25 mg Ce/kg) on the nutritional components of soil-cultivated corn and soybean plants were evaluated. Both treatments tended to decrease the dry weight of grain per plant, while only 225 mg/kg CeO₂ NPs on soybean and CeCl₃ on corn showed statistical significance compared with the respective control. CeO₂ NPs at 225 mg/kg significantly decreased the content of starch in the corn kernels by 18.2% but increased total phenols in soybean seeds by 18.4%. Neither CeO₂ NPs nor CeCl₃ significantly affected the contents of minerals in corn kernels except for Zn. However, in the case of soybean, the two treatments tended to decrease the contents of P, Zn, Mn, and Mo but increase the content of S. Overall, the results suggest that CeO₂ NPs and Ce³⁺ ions showed similar but not identical effects on corn and soybean plants. CeO₂ NPs affect the nutritional quality of crop plants in a species-dependent manner.

Mitogen-like Cerium-Based Nanoparticles Protect Schmidtea mediterranea against Severe Doses of X-rays

Novel radioprotectors are strongly demanded due to their numerous applications in radiobiology and biomedicine, e.g., for facilitating the remedy after cancer radiotherapy. Currently, cerium-containing nanomaterials are regarded as promising inorganic radioprotectors due to their unrivaled antioxidant activity based on their ability to mimic the action of natural redox enzymes like catalase and superoxide dismutase and to neutralize reactive oxygen species (ROS), which are by far the main damaging factors of ionizing radiation. The freshwater planarian flatworms are considered a promising system for testing new radioprotectors, due to the high regenerative potential of these species and an excessive amount of proliferating stem cells (neoblasts) in their bodies. Using planarian Schmidtea mediterranea, we tested CeO₂ nanoparticles, well known for their antioxidant activity, along with much less studied CeF₃ nanoparticles, for their radioprotective potential. In addition, both CeO₂ and CeF₃ nanoparticles improve planarian head blastema regeneration after ionizing irradiation by enhancing blastema growth, increasing the number of mitoses and neoblasts' survival, and modulating the expression of genes responsible for the proliferation and differentiation of neoblasts. The CeO₂ nanoparticles' action stems directly from their redox activity as ROS scavengers, while the CeF₃ nanoparticles' action is mediated by overexpression of "wound-induced genes" and neoblast- and stem cell-regulating genes.

Cerium improves the physiology and medicinal components of Dendrobium nobile Lindl. under copper stress

Heavy metal stress affects the quality of medicinal plants, and rare earth elements can effectively alleviate heavy metal stress. In this paper, we investigated the effects of rare earth element cerium (0, 5, 10, 20, 40, 80, and 160 mg/L) on the physiological and medicinal components of Dendrobium nobile Lindl. under copper (200 mg/L) stress. The results revealed that cerium (Ce) had a good alleviating effect on copper (Cu) stress, low concentrations of Ce (10-20 mg/L) significantly improved the resistance and medicinal qualities of the plant such as polysaccharide, polyphenol and flavonoid, it also increased the content of photosynthetic pigment, proline, soluble sugar and soluble protein of D. nobile Lindl., effectively balance the osmotic pressure and the generation and removal of reactive oxygen species in the plant, thereby the toxic effect of copper on D. nobile Lindl. is alleviated. From the point of view of the treatment time when the optimal relieving concentration appeared, the optimal concentration for relieving antioxidant enzyme activity all appeared at the treatment time of 10 d, the optimum concentrations of other indicators all appeared at the treatment time of 15 d. Overall, this study suggests that the optimum level of Ce (10-20 mg/L) might be promising for alleviating the adverse impacts of copper stress and promoting the accumulation of medicinal components in D. nobile Lindl.

Role of Cerium Oxide Nanoparticles and Doxorubicin in Improving Cancer Management: A Mini Review

Cancer is one of the significant issues with public health and the second leading cause of death worldwide. The three most lethal cancers in the general population are stomach, lung, and liver cancers, in which lung and breast cancers cause the majority of cancer-associated deaths among men and women, respectively. CeO2 nanoparticles have a cytoprotectant effect in normal cells and a cytotoxic effect in cancer cells that enables them to induce the reactive oxygen species (ROS) production within cancer cells, which in turn develops reactive nitrogen species (RNS) that interfere with intracellular activities, and this property makes them an excellent anticancer agent. Because of its biofilm suppression, free radical scavenging ability, redox activity, and other unique properties, attention has been bestowed on cerium oxide nanoparticles as a potential alternative to solve many biomedical issues in the future. This review mainly focuses on the combinatorial effect of cerium dioxide nanoparticles and Doxorubicin in cancer management.

Nanoceria as an Electron Reservoir: Spontaneous Deposition of Metal Nanoparticles on Oxides and Their Anti-inflammatory Activities

Designing metal-metal oxide heteronanostructures with synergistic and superior activities (unattainable in the case of a single entity) is of great interest for a wide range of technological applications. Traditional synthetic strategies typically require reducing agents, stabilizing ligands, or high temperature reductive treatment to produce oxide-supported metals. Herein, a facile noble metal deposition strategy is developed to produce silver, gold, and platinum nanocrystals on the surface of hollow mesoporous cerium oxide nanospheres without any pretreatment. Unlike the galvanic replacement reaction, the developed protocol employs the innate reductive potential of CeO₂ to produce a high density of ultrafine noble metal nanocrystals homogeneously immobilized onto the surface of CeO₂ nanospheres. The multienzyme-like activities (i.e., superoxide dismutase-like and catalase-like) of CeO₂@metal nanostructures, originating from CeO₂ and metal nanoparticles, were effectively utilized for anti-inflammatory therapies in two in vivo models. This oxygen vacancy-mediated reduction strategy can be generalized to produce diverse metal-metal oxide nanostructures for a wide range of applications.

A simple method for the preparation of CeO2with high antioxidant activity and wide application range

Cerium oxide (CeO₂) is a well-known antioxidant with the ability to scavenge reactive oxygen species due to its unique electronic structure and chemical properties. Although many methods to enhance the antioxidant activity of CeO₂have been reported, its antioxidant activity is still not high enough, and some enhancement effects are limited by the material concentration. There are also some CeO₂obtained with high antioxidant activity at high concentrations, which is not conducive to the application of biomedicine. Therefore, it is urgent to obtain CeO₂material with low cell cytotoxicity, high antioxidant activity and wide application range. In this work, rod-like metal organic framework derived CeO₂(CeO₂-MOF) was prepared by a simple method. Compared with the CeO₂nanorods prepared by hydrothermal method, it shows better antioxidant activity compared with the CeO₂nanorods prepared by hydrothermal method. Moreover, the advantage of CeO₂-MOF's antioxidant activity is not affected by the hydroxyl radical and material concentrations The reason why CeO₂-MOF has higher antioxidant activity should be attributed to its higher Ce³⁺content and larger specific surface area. In addition, CeO₂-MOF also exhibits low cytotoxicity to HeLa cells and PC12 cellsin vitro. The strategy of using MOF as a structural and compositional material to create CeO₂provides a new method to explore highly efficient and biocompatible CeO₂for practical applications.

Design of Monovalent Cerium-Based Metal Organic Frameworks as Bioinspired Superoxide Dismutase Mimics for Ionizing Radiation Protection

Superoxide dismutase (SOD) is one of the major antioxidants in vivo and is expected to play critical roles on the defense against reactive oxygen species (ROS)-mediated damages, such as ionizing radiation damages. Herein, inspired by the function and structure of natural SODs and cerium oxide nanozymes, two monovalent cerium-based metal organic frameworks (Ce-MOFs), Ce^IIIBTC and Ce^IVBTC, were designed for superoxide radical (O₂^•-) elimination and ionizing radiation protection. These two Ce-MOFs selectively scavenge O₂^•- and are excellent SOD mimics. Like natural SODs and cerium oxide nanozymes, the SOD-like catalytic mechanism of Ce-MOFs involves a cycle between Ce(IV) and Ce(III). Furthermore, by constructing monovalent Ce-MOFs, we found that high-valent Ce^IVBTC are more effective SOD-like nanozymes compared to Ce^IIIBTC. With smaller size, better monodispersity, and more effective SOD-like activity, Ce^IVBTC nanozymes were further applied for ionizing radiation protection. Both in vitro and in vivo results demonstrated that Ce^IVBTC nanozymes could efficiently scavenge ROS, prevent cells from γ-ray radiation-induced cell viability decrease and DNA damages, and improve the survival rate of irradiated mice by recovering the bone marrow DNA damage and alleviating oxidative stress of tissues. The protective effect and good biocompatibility of Ce^IVBTC nanozymes will enable the development of Ce-MOFs-based radioprotectants and facilitate treatment of other ROS-related diseases.

Cerium Oxide Nanorods Synthesized by Dalbergia sissoo Extract for Antioxidant, Cytotoxicity, and Photocatalytic Applications

In this study, cerium oxide nanorods (CeO₂-NRs) were synthesized by using the phytochemicals present in the Dalbergia sissoo extract. The physiochemical characteristics of the as-prepared CeO₂-NRs were investigated by using ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The SEM and UV-VIS analyses revealed that the acquired nanomaterials possessed a rod-like morphology while the XRD results further confirmed that the synthesized NRs exhibited a cubic crystal lattice system. The antioxidant capacity of the synthesized CeO₂-NRs was investigated by using several in vitro biochemical assays. It was observed that the synthesized NRs exhibited better antioxidant potential in comparison to the industrial antioxidant of the butylated hydroxyanisole (BHA) in 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The biochemical assays, including lipid peroxidation (LPO), total antioxidant capacity (TAC), and catalase activity (CAT), were also performed in the human lymphocytes incubated with the CeO₂-NRs to investigate the impact of the NRs on these oxidative biomarkers. Enhanced reductive capabilities were observed in all the assays, revealing that the NRs possess excellent antioxidant properties. Moreover, the cytotoxic potential of the CeO₂-NRs was also investigated with the MTT assay. The CeO₂-NRs were found to effectively kill off the cancerous cells (MCF-7 human breast cancer cell line), further indicating that the synthesized NRs exhibit anticancer potential as well. One of the major applications studied for the prepared CeO₂-NRs was performing the statistical optimization of the photocatalytic degradation reaction of the methyl orange (MO) dye. The reaction was optimized by using the technique of response surface methodology (RSM). This advanced approach facilitates the development of the predictive model on the basis of central composite design (CCD) for this degradation reaction. The maximum degradation of 99.31% was achieved at the experimental optimized conditions, which corresponded rather well with the predicted percentage degradation values of 99.58%. These results indicate that the developed predictive model can effectively explain the performed experimental reaction. To conclude, the CeO₂-NRs exhibited excellent results for multiple applications.

A synergistic chemodynamic-photodynamic-photothermal therapy platform based on biodegradable Ce-doped MoOx nanoparticles

Near-infrared light-induced catalysts are considered to be potential nanoagents for tumor therapy. Cerium (Ce) is a non-biotoxic lanthanide element and exhibits variable valence states for catalytic reactions. In this work, we report a one-step hydrothermal synthesis for Ce-doped MoO_x (CMO) nanomaterials. The obtained CMO nanomaterials show high absorption in the NIR II regime and a high photothermal conversion efficiency of 67.7% (1064 nm). Moreover, due to the doping of Ce element, the consumption of hydrogen peroxide (H₂O₂) and glutathione (GSH) is boosted which enhances the chemodynamic and photodynamic therapy simultaneously. Under NIR II laser irradiation, the designed CMO nanocatalysts induce metabolism disruption and mitochondrial damage in the tumor cells. As-prepared CMO nanomaterials also show good biocompatibility and pH-responsive degradation behavior, which can be degraded rapidly under alkaline conditions (pH = 7.4) and remain stable in acidic solution (pH = 5.6). These properties make CMO nanomaterials ideal biodegradable nanotheranostic agents for synergistic chemodynamic-photodynamic-photothermal antitumor therapy.

Antioxidant Effects of Bioactive Glasses (BGs) and Their Significance in Tissue Engineering Strategies

Elevated levels of oxidative stress are usually observed following injuries, leading to impaired tissue repair due to oxidation-related chronic inflammation. Several attempts have been made to manage this unfavorable situation, and the use of biomaterials with antioxidant activity is showing great promise in tissue engineering and regenerative medicine approaches. Bioactive glasses (BGs) are a versatile group of inorganic substances that exhibit an outstanding regenerative capacity for both hard and soft damaged tissues. The chemical composition of BGs provides a great opportunity for imparting specific biological activities to them. On this point, BGs may easily become antioxidant substances through simple physicochemical modifications. For example, particular antioxidant elements (mostly cerium (Ce)) can be added to the basic composition of the glasses. On the other hand, grafting natural antioxidant substances (e.g., polyphenols) on the BG surface is feasible for making antioxidant substitutes with promising results in vitro. Mesoporous BGs (MBGs) were demonstrated to have unique merits compared with melt-derived BGs since they make it possible to load antioxidants and deliver them to the desired locations. However, there are actually limited in vivo experimental studies on the capability of modified BGs for scavenging free radicals (e.g., reactive oxygen species (ROS)). Therefore, more research is required to determine the actual potential of BGs in decreasing oxidative stress and subsequently improving tissue repair and regeneration. The present work aims to highlight the potential of different types of BGs in modulating oxidative stress and subsequently improving tissue healing.

Cerium oxide thin films: synthesis, characterization, photocatalytic activity and influence on microbial growth

The resistance of surfaces to biofouling remains a significant advantage for optical devices working in natural conditions, increasing their lifetime and reducing maintenance costs. This paper reports on the functionalities of transparent CeO₂ thin films with thicknesses between 25 and 600 nm deposited by reactive magnetron sputtering on the glass substrate. The CeO₂ photocatalytic performance exhibited an efficiency of 30% on imidacloprid degradation under 6 h of UV radiation and increased linearly with the irradiation time, suggesting a complete degradation within 48 h. The films did not alter the growth rate of the green algae Chlorella vulgaris after 72 h short-term exposure. The tested CeO₂ films proved to efficiently inhibit with high efficiency the Staphylococcus aureus biofilms and planktonic growth (reducing the counts of bacterial cells by 2 to 8 logs), demonstrating the promising potential of these materials for obtaining antimicrobial and antibiofilm surfaces, with broad applications for the biomedical, ecological and industrial fields.

Preparation, Characterization and Multiple Biological Properties of Peptide-Modified Cerium Oxide Nanoparticles

Although cerium oxide nanoparticles are attracting much attention in the biomedical field due to their unique physicochemical and biological functions, the cerium oxide nanoparticles greatly suffer from several unmet physicochemical challenges, including loss of enzymatic activity during the storage, non-specific cellular uptake, off-target toxicities, etc. Herein, in order to improve the targeting property of cerium oxide nanoparticles, we first modified cerium oxide nanoparticles (CeO₂) with polyacrylic acid (PAA) and then conjugated with an endothelium-targeting peptide glycine-arginine-aspartic acid (cRGD) to construct CeO₂@PAA@RGD. The physiochemical characterization results showed that the surface modifications did not impact the intrinsic enzymatic properties of CeO₂, including catalase-like (CAT) and superoxide dismutase-like (SOD) activities. Moreover, the cellular assay data showed that CeO₂@PAA@RGD exhibited a good biocompatibility and a higher cellular uptake due to the presence of RGD targeting peptide on its surface. CeO₂@PAA@RGD effectively scavenged reactive oxygen species (ROS) to protect cells from oxidative-stress-induced damage. Additionally, it was found that the CeO₂@PAA@RGD converted the phenotype of macrophages from proinflammatory (M1) to anti-inflammatory (M2) phenotype, inhibiting the occurrence of inflammation. Furthermore, the CeO₂@PAA@RGD also promoted endothelial cell-mediated migration and angiogenesis. Collectively, our results successfully demonstrate the promising application of CeO₂@PAA@RGD in the future biomedical field.

Facet-Dependent Activity of CeO2 Nanozymes Regulate the Fate of Human Neural Progenitor Cell via Redox Homeostasis

Neural progenitor cells (NPCs) therapy, a promising therapeutic strategy for neurodegenerative diseases, has a huge challenge to ensure high survival rate and neuronal differentiation rate. Cerium oxide (CeO₂) nanoparticles exhibit multienzyme mimetic activities and have shown the capability of regulating reactive oxygen species (ROS), which is a pivotal mediator for intracellular redox homeostasis in NPCs, regulating biological processes including differentiation, proliferation, and apoptosis. In the present study, the role of facet-dependent CeO₂-mediated redox homeostasis in regulating self-renewal and differentiation of NPCs is reported for the first time. The cube-, rod-, and octahedron-shaped CeO₂ nanozymes with different facets are prepared. Among the mentioned nanozymes, the cube enclosed by the (100) facet exhibits the highest CAT-like activity, causing it to provide superior protection to NPCs from oxidative stress induced by H₂O₂; meanwhile, the octahedron enclosed by the (111) facet with the lowest CAT-like activity induces the most ROS production in ReNcell CX cells, which promotes neuronal differentiation by activated AKT/GSK-3β/β-catenin pathways. A further mechanistic study indicated that the electron density of the surface Ce atoms changed continuously with different crystal facets, which led to their different CAT-like activity and modulation of redox homeostasis in NPCs. Altogether, the different surface chemistry and atomic architecture of active sites on CeO₂ exert modulation of redox homeostasis and the fate of NPCs.

Acute Oral Administration of Cerium Oxide Nanoparticles Suppresses Lead Acetate-Induced Genotoxicity, Inflammation, and ROS Generation in Mice Renal and Cardiac Tissues

Lead, a highly toxic pollutant, causes numerous health problems and affects nearly all biological systems thus arousing interest in using antioxidants to reduce its toxic effects. Therefore, the undertaken study estimated the influence of cerium oxide nanoparticles (CeO2-NPs) on the lead acetate-induced genotoxicity and inflammation in the kidney and heart tissues of mice. Twenty male mice were randomly divided into negative control and lead acetate and/or CeO2-NPs administrated groups. Comet and diphenylamine assays were conducted to assess the DNA damage and the expression of apoptosis-related genes and inflammatory cytokines were also measured in addition to the estimation of reactive oxygen species (ROS) level. Co-administration of CeO2-NPs significantly reduced the DNA damage and ROS generation caused by lead acetate in the kidney and heart tissues. The co-administration of CeO2-NPs also ameliorated the lead acetate-induced dysregulation in the expression levels of p53, K-ras, interleukin-6, and cyclooxygenase-2 in the kidney and heart. Conclusion: the co-administration of CeO2-NPs suppresses the genotoxicity, inflammation, and ROS generation resulting from lead acetate administration and restoring the genomic DNA integrity; thus, administration of CeO2-NPs is recommended to minimize the lead acetate-induced hazards.

Effect of Cerium Oxide Nanoparticles on the Expression of Developmental and Apoptosis Genes of Testicular Tissue in 6-Day-Old NMRI Mice Fetuses

Cerium oxide (CeO₂) has potential applications in medicine and various consumer products. This study investigated the effect of CeO₂ on the expression of genes associated with apoptosis and testicular development in mouse embryos. The experimental groups of pregnant mice were injected intraperitoneally with CeO₂ at a concentration of 10 mg/kg on days 7 and 14 of pregnancy. Six days after birth, the testicles of neonatal male mice were collected for mRNA expression determination using real-time PCR, protein expression analysis by immunohistochemistry, and apoptotic cell population determination using the TUNEL assay. The results showed that the mRNA expression of the Bax, Caspase-3, and Gsk3-β genes, unlike the Bcl2 gene, decreased significantly in the experimental group compared to the control group. The expression ratio of Bax/Bcl2 in the experimental group was lower than in the control group. A similar trend was observed in the population of apoptotic cells. In the experimental group, the expression levels of, Gata4, Sox8, and Rad54 at both the mRNA and protein levels increased significantly compared to the control group. Based on the results of this study, CeO₂ at a concentration of 10 mg/kg, in addition to producing anti-apoptotic effects on the testicular cells of neonatal mice, can increase the expression of genes involved in testicular development and performance. The current experimental study proved the protective effects of 10 mg/kg CeO₂ in developmental and apoptosis genes of testicular tissue in 6-day-old NMRI mice fetuses; however, more experiments are required to evaluate the possible side effects and interactions.

Foliar Application of Cerium Oxide-Salicylic Acid Nanoparticles (CeO2:SA Nanoparticles) Influences the Growth and Physiological Responses of Portulaca oleracea L. under Salinity

In the present study, the effects of foliar application of salicylic acid (100 μM), cerium oxide (50 mg L⁻¹), and cerium oxide:salicylic acid nanoparticles (CeO₂: SA-nanoparticles, 50 mg L⁻¹ + 100 μM) on the growth and physiological responses of purslane (Portulaca oleracea L.) were examined in non-saline and saline conditions (50 and 100 mM NaCl salinity). Foliar applications mitigated salinity-induced adverse effects, and the highest plant height and N, P, Mg, and Mn content were recorded in the variant with non-saline × foliar use of CeO₂: SA-nanoparticles. The highest values of fresh and dry weight were noted in the treatment with no-salinity × foliar use of CeO₂:SA-nanoparticles. The highest number of sub-branches was observed in the foliar treatments with CeO₂-nanoparticles and CeO₂:SA-nanoparticles without salinity stress, while the lowest number was noted in the 100 mM NaCl treatment. Moreover, the foliar application of CeO₂:SA-nanoparticles and cerium-oxide nanoparticles improved the total soluble solid content, K, Fe, Zn, Ca, chlorophyll a, and oil yield in the plants. The salinity of 0 and 50 mM increased the K content, 1000-seed weight, total soluble solid content, and chlorophyll b content. The use of 100 mM NaCl with no-foliar spray increased the malondialdehyde, Na, and H₂O₂ content and the Na⁺/K⁺ ratio. No-salinity and 50 mM NaCl × CeO₂: SA-nanoparticle interactions improved the anthocyanin content in plants. The phenolic content was influenced by NaCl₁₀₀ and the foliar use of CeO₂:SA-nanoparticles. The study revealed that the foliar treatment with CeO₂:SA-nanoparticles alleviated the side effects of salinity by improving the physiological responses and growth-related traits of purslane plants.

Toxicity mechanism of cerium oxide nanoparticles on cyanobacteria Microcystis aeruginosa and their ecological risks

The extensive application of cerium oxide nanoparticles (CeO₂ NPs), a type of rare earth nanomaterial, led to pollution into aquatic environments. Cyanobacteria, a significant component of freshwater ecosystems, can interact with CeO₂ NPs. However, little attention has been paid as to whether CeO₂ NPs will have adverse effects on cyanobacteria. In the present study, Microcystis aeruginosa (FACHB-942) was exposed to different concentrations (0, 1, 10, and 50 mg/L) of CeO₂ NPs. Results showed 50 mg/L CeO₂ NPs inhibited algal growth (11.48% ± 5.76%), suppressed photosynthesis and induced the generation of reactive oxygen species (ROS) after 72 h exposure. The toxicity mechanism is the adsorption of CeO₂ NPs on cell surface, the ROS formation and the intracellular Ce. Additionally, the intracellular microcystins (MCs) content was significantly induced (11.84% ± 1.47%) by 50 mg/L CeO₂ NPs, while no significance was found in 1 and 10 mg/L CeO₂ NP treatments. Results indicated high concentrations of CeO₂ NPs could be toxic to algae through the adverse effects on algal growth and photosynthesis. Moreover, the promoted MCs production could also pose a threat to freshwater ecosystems due to the possible release into the environment.

A biomimetic zeolite-based nanoenzyme contributes to neuroprotection in the neurovascular unit after ischaemic stroke via efficient removal of zinc and ROS

Zeolite-based nanomaterials have a large number of applications in the field of medicine due to their high porosity, biocompatibility and biological stability. In this study, we designed cerium (Ce)-doped Linde Type A (LTA) zeolite-based nanomaterials (Ce/Zeo-NMs) as a multifunctional mesoporous nanoenzyme to reduce dysfunction of the neurovascular unit (NVU) and attenuate cerebral ischaemia-reperfusion (I/R) injury. Owing to its unique adsorption capacity and mimetic catalytic activities, Ce@Zeo-NMs adsorbed excess zinc ions and exhibited scavenging activity against reactive oxygen species (ROS) induced by acute I/R, thus reshaping the oxidative and zinc microenvironment in the ischaemic brain. In vivo results demonstrated that Ce@Zeo-NMs significantly reduced ischaemic damage to the NVU by decreasing the infarct area, protecting against breakdown of the blood-brain barrier (BBB) via inhibiting the degradation of tight junction proteins (TJPs) and inhibiting activation of microglia and astrocytes in a rat model of middle cerebral artery occlusion-reperfusion (MCAO/R). Taken together, these findings indicated that Ce@Zeo-NMs may serve as a promising dual-targeting therapeutic agent for alleviating cerebral I/R injury. STATEMENT OF SIGNIFICANCE: Cerium (Ce)-doped Linde Type A zeolite-based nanomaterials (Ce/Zeo-NMs) as a multifunctional mesoporous nanoenzyme were designed for inducing neuroprotection after ischaemic stroke by reducing dysfunction of the neurovascular unit (NVU). Ce@Zeo-NMs had the ability to adsorb excessive Zn²⁺ and showed mimetic enzymatic activities. As a result, Ce@Zeo-NMs protected against cerebral ischaemia and reduced the damage of NVU by improving the integrity of blood brain barrier (BBB) and inhibiting activation of microglia and astrocytes in a rat model of middle cerebral artery occlusion-reperfusion (MCAO/R). These findings indicated that Ce@Zeo-NMs may serve as a therapeutic strategy for neuroprotection and functional recovery upon ischaemic stroke onset.

The Use of Cerium Compounds as Antimicrobials for Biomedical Applications

Cerium and its derivatives have been used as remedies for wounds since the early 20th century. Cerium nitrate has attracted most attention in the treatment of deep burns, followed later by reports of its antimicrobial properties. Its ability to mimic and replace calcium is presumed to be a major mechanism of its beneficial action. However, despite some encouraging results, the overall data are somewhat confusing with seemingly the same compounds yielding opposing results. Despite this, cerium nitrate is currently used in wound treatment in combination with silver sulfadiazine as Flammacérium. Cerium oxide, especially in nanoparticle form (Nanoceria), has lately captured much interest due to its antibacterial properties mediated via oxidative stress, leading to an increase of published reports. The properties of Nanoceria depend on the synthesis method, their shape and size. Recently, the green synthesis route has gained a lot of interest as an alternative environmentally friendly method, resulting in production of effective antimicrobial and antifungal nanoparticles. Unfortunately, as is the case with antibiotics, emerging bacterial resistance against cerium-derived nanoparticles is a growing concern, especially in the case of bacterial biofilm. However, diverse strategies resulting from better understanding of the biology of cerium are promising. The aim of this paper is to present the progress to date in the use of cerium compounds as antimicrobials in clinical applications (in particular wound healing) and to provide an overview of the mechanisms of action of cerium at both the cellular and molecular level.

Haloperoxidase-mimicking CeO2-x nanorods for the deactivation of human coronavirus OC43

Despite the excellent antibacterial and antifouling effects of haloperoxidase (HPO)-mimicking CeO_2-x nanorods, their antiviral efficiency has not been explored. Herein, we designed and synthesized CeO_2-x nanorods with varying aspect ratios via the hydrothermal method. CeO_2-x nanorods catalysed the oxidative bromination of Br^- and H₂O₂ to HOBr, the kinetics of which were studied systematically using a phenol red assay. The CeO_2-x nanorods with the optimized aspect ratio (i.e., 4.5) demonstrated strong antiviral efficacies against the human coronavirus OC43, with no visible toxicity to the HCT-8 host cells.

Cerium oxide nanozyme attenuates periodontal bone destruction by inhibiting the ROS-NFκB pathway

Periodontitis, an inflammatory disease of oxidative stress, occurs due to excess reactive oxygen species (ROS) contributing to cell and tissue damage which in turn leads to alveolar bone resorption as well as the destruction of other periodontal support tissues. With significant recent advances in nanomaterials, we considered a unique type of nanomaterials possessing enzyme-like characteristics (called nanozymes) for potential future clinical applications, especially in light of the increasing number of studies evaluating nanozymes in the setting of inflammatory diseases. Here, we introduced a therapeutic approach for the management of periodontitis utilizing an injection of cerium oxide nanoparticles (CeO₂ NPs) in situ. In this study, our synthesized CeO₂ NPs could act as ROS scavengers in the inflammatory microenvironment with ideal outcomes. In vitro and in vivo experiments provide strong evidence on the roles of CeO₂ NPs in scavenging multiple ROS and suppressing ROS-induced inflammation reactions stimulated by lipopolysaccharides. Moreover, CeO₂ NPs could inhibit the MAPK-NFκB signalling pathway to suppress inflammatory factors. In addition, the results from a rat periodontitis model demonstrate that CeO₂ NPs could exhibit a remarkable capacity to attenuate alveolar bone resorption, decrease the osteoclast activity and inflammation, and consequently improve the restoration of destroyed tissues. Collectively, our present study underscores the potential of CeO₂ NPs for application in the treatment of periodontitis, and provides valuable insights into the application of nanozymes in inflammatory diseases.

Cerium oxide nanoparticle conjugation to microRNA-146a mechanism of correction for impaired diabetic wound healing

Diabetic wounds represent a significant healthcare burden and are characterized by impaired wound healing due to increased oxidative stress and persistent inflammation. We have shown that CNP-miR146a synthesized by the conjugation of cerium oxide nanoparticles (CNP) to microRNA (miR)-146a improves diabetic wound healing. CNP are divalent metal oxides that act as free radical scavenger, while miR146a inhibits the pro-inflammatory NFκB pathway, so CNP-miR146a has a synergistic role in modulating both oxidative stress and inflammation. In this study, we define the mechanism(s) by which CNP-miR146a improves diabetic wound healing by examining immunohistochemical and gene expression analysis of markers of inflammation, oxidative stress, fibrosis, and angiogenesis. We have found that intradermal injection of CNP-miR146a increases wound collagen, enhances angiogenesis, and lowers inflammation and oxidative stress, ultimately promoting faster closure of diabetic wounds.

Gold Nanorods with Spatial Separation of CeO2 Deposition for Plasmonic-Enhanced Antioxidant Stress and Photothermal Therapy of Alzheimer's Disease

Activities of catalase (CAT) and superoxide dismutase (SOD) of ceria nanoparticles (CeO₂ NPs) provide the possibility for their application in nervous system oxidative stress diseases including Alzheimer's disease (AD). The addition of hot electrons produced by a plasma photothermal effect can expand the photocatalytic activity of CeO₂ to the near-infrared region (NIR), significantly improving its redox performance. Therefore, we coated both ends of gold nanorods (Au NRs) with CeO₂ NPs, and photocatalysis and photothermal therapy in the NIR are introduced into the treatment of AD. Meanwhile, the spatially separate structure enhances the catalytic performance and photothermal conversion efficiency. In addition, the photothermal effect significantly improves the permeability of the blood-brain barrier (BBB) and overcomes the shortcomings of traditional anti-AD drugs. To further improve the therapeutic efficiency, Aβ-targeted inhibitory peptides were modified on the middle surface of gold nanorods to synthesize KLVFF@Au-CeO₂ (K-CAC) nanocomposites. We have verified their biocompatibility and therapeutic effectiveness at multiple levels in vitro and in vivo, which have a profound impact on the research and clinical transformation of nanotechnology in AD therapy.