Search Results (378)

The increasing use of Technology-Critical Elements (TCEs) in modern technology has led to widespread environmental release, raising questions about their biological effects, as emerging evidence suggests significant toxicity. We investigated the effects of three technology-critical elements, Indium oxide (In₂O₃), Lanthanum nitrate hexahydrate (La(NO₃)₃·6H₂O) and Cerium(III) nitrate hexahydrate (Ce(NO₃)₃·6H₂O), on human dermal fibroblasts (BJ) and hepatocarcinoma cells (HepG2), assessing their uptake, impact on viability, and induced cellular stress responses, quantified by markers of inflammation, oxidative stress, and membrane damage. Our results show a strong differential susceptibility: normal BJ fibroblasts proved vulnerable, whereas HepG2 cells were highly resistant. This divergence occurred despite substantial and comparable accumulation of all three TCEs in both cell lines, indicating that toxicity is uncoupled from the magnitude of the uptake. Mechanistically, the differential toxicity correlated strongly with opposing antioxidant responses. Additionally, low concentrations of cerium (III) nitrate (12.5–50 µg/mL) uniquely stimulated the proliferation of HepG2 cells (up to 129% of control). While these findings identify multiple mechanistic hazards regarding the potential of low-level technology-critical element exposure, they must be interpreted cautiously and warrant further investigation in more complex biological models. Full article

Supercapacitors based on mixed metal oxides are being developed as potential devices for large-scale energy storage applications with physical flexibility, thanks to their low cost and good electrochemical performance. This work demonstrates a novel approach to enhancing the electrochemical performance of bismuth–cerium oxide BiCeO₃ (BC) through thiourea doping. The incorporation of sulfur, confirmed by EDS, induced significant structural modifications, including a reduction in crystallite size from 42.5 nm to 34.8 nm and the emergence of new diffraction planes (002) and (222) in XRD patterns. These changes, indicative of successful lattice doping, yielded a more nanostructured morphology with increased active surface area and a 20% reduction in the optical band gap. Electrochemically, the thiourea-doped BiCeO₃ (BCT) electrode delivered a marked improvement, exhibiting a specific capacitance of 150 F·g⁻¹ at 25 mV·s⁻¹, a 17.2% increase over the pure BiCeO₃ (128 F·g⁻¹). Furthermore, BCT demonstrated superior rate capability and a 43% reduction in overall impedance, underscoring enhanced charge transfer kinetics and ionic conductivity. The synergy between sulfur-induced structural defects, increased electroactive surface area, and improved electronic structure establishes thiourea doping as an effective strategy for developing high-performance BiCeO₃-based supercapacitors. Full article

Titania catalysts containing cerium, copper, or iron were obtained using the sol–gel method and tested in the selective reduction of nitrogen oxide. Samples with cerium and iron showed high activity at temperatures ranging from 200 to 400 °C, without the formation of N₂O. The materials crystallized in anatase structure, and only a small amount of ceria was detected by XRD. Their crystallites were nanometric in size. The solids were mesoporous, with a specific surface area between 74 and 160 m²/g, determined based on nitrogen sorption at low temperature. The optimum Ce/Ti and Fe/Ti atomic ratio was 0.1 to 0.9, and such catalysts were composed of small anatase crystallites, although the presence of ceria also resulted in high catalytic activity. This activity was due to the presence of Fe³⁺ or Ce³⁺ ions on the surface of the material. Full article

Rare-earth oxide (REO) nanoparticles (NPs)—such as cerium (CeO₂), samarium (Sm₂O₃), neodymium (Nd₂O₃), terbium (Tb₄O₇), and praseodymium (Pr₂O₃)—have demonstrated strong antimicrobial activity against multidrug-resistant bacteria. Their effectiveness is attributed to unique physicochemical properties, including oxygen vacancies and redox cycling, which facilitate the generation of reactive oxygen species (ROS) that damage microbial membranes and biomolecules. Additionally, electrostatic interactions with microbial surfaces and sustained ion release contribute to membrane disruption and long-term antimicrobial effects. REOs also inhibit bacterial enzymes, DNA, and protein synthesis, providing broad-spectrum activity against Gram-positive, Gram-negative, and fungal pathogens. However, dose-dependent cytotoxicity to mammalian cells—primarily due to excessive ROS generation—and nanoparticle aggregation in biological media remain challenges. Surface functionalization with polymers, peptides, or metal dopants (e.g., Ag, Zn, and Cu) can mitigate cytotoxicity and enhance selectivity. Scalable and sustainable synthesis remains a challenge due to high synthesis costs and scalability issues in industrial production. Green and biogenic routes using plant or microbial extracts can produce REOs at lower cost and with improved safety. Advanced continuous flow and microwave-assisted synthesis offer improved particle uniformity and production yields. Biomedical applications include antimicrobial coatings, wound dressings, and hybrid nanozyme systems for oxidative disinfection. However, comprehensive and intensive toxicological evaluations, along with regulatory frameworks, are required before clinical deployment. Full article

Birnessite has a strong ability to fix rare-earth elements (REEs), but the transformation process of birnessite and its effects on the migration of these elements are not well understood. This study examines how pH and Mn(II) concentrations influence the transformation of cerium-adsorbed hexagonal birnessite (Ce/HB) and the behaviors of Ce and Mn. The results show that the effect of Mn(II) on Ce/HB transformation strongly depended on solution pH. At a pH of 5.0, HB initially underwent transformation into feitknechtite, followed by further disproportionation that resulted in the regeneration of HB and Mn(II). Concurrently, redox reactions occur between Mn(IV) in MnO₂ (a secondary phase of HB) and Ce(III)/Mn(II), creating a local redox gradient that facilitates partial HB transformation. At pH = 7.0, Mn(II) reduces the crystallinity of transformed products while enhancing the thermodynamic stability of feitknechtite, making it the dominant manganese oxide phase. At pH = 9.0, high-concentration Mn(II) causes lattice distortion in original HB; Ce(III) acts as a structural inducer, promoting mineral transition from hexagonal to orthorhombic symmetry, while excess soluble Mn(II) precipitates new feitknechtite. Additionally, surplus Mn(II) could engage in interfacial redox reactions with high-valent manganese oxides to generate secondary feitknechtite. Ce primarily exists as Ce(IV), forming CeO₂ on the mineral surface via oxidation reactions that significantly increase hydroxylation and surface reactivity. This study clarifies the transformation pathways of manganese oxides and the migration and transformation patterns of Ce and Mn in rare-earth-rich mining areas. Full article

There is an urgent need to evaluate the toxicity of xenobiotics and environmental mixtures for preventing loss in water quality for the sustainability of aquatic ecosystems. A simple prebiotic chemical pathway based on malate formation from pyruvate (pyr) and glyoxalate (glyox) is proposed as a quick and cheap screening tool for toxicity assessment. The assay is based on the pyr and glyox (aldol) condensation reactions, leading to biologically relevant precursors such as oxaloacetate and malate. Incubation of pyr and glyox at 40–70 °C in the presence of reduced iron Fe(II) led to malate formation following the first 3 h of incubation. The addition of various xenobiotics/contaminants (silver, copper, zinc, cerium IV, samarium III, dibutylphthalate, 1,3-diphenylguanidine, carbon-walled nanotube, nanoFe₂O₃ and polystyrene nanoparticles) led to inhibitions in malate synthesis at various degrees. Based on the concentration inhibiting malate concentrations by 20% (IC20), the following potencies were observed: silver < copper ~ 1.3-diphenylguanidine ~ carbon-walled nanotube < zinc ~ samarium < dibutylphthalate ~ samarium < Ce(IV) < nFeO₃ < polystyrene nanoplastics. The IC20 values were also significantly correlated with the reported trout acute lethality data, suggesting its potential as an alternative toxicity test. The pyr-glyox pathway was also tested on surface water extracts (C18), identifying the most contaminated sites from large cities and municipal wastewater effluents dispersion plume. The inhibition potencies of the selected test compounds revealed that not only pro-oxidants but also chemicals hindering enolate formation, nucleophilic attack of carbonyls and dehydration involved in aldol-condensation reactions were associated with toxicity. The pyr-glyox pathway is based on prebiotic chemical reactions during the emergence of life and represents a unique tool for identifying toxic compounds individually and in complex mixtures. Full article

This study examines the rheological and tribological behavior of bio-based nano-lubricants enhanced with cerium oxide (CeO₂) and multi-walled carbon nanotubes (MWCNTs), alongside the application of artificial intelligence (AI) models for performance prediction. Rheological results confirmed non-Newtonian, shear-thinning behavior across all formulations. CeO₂-based lubricants exhibited significantly higher viscosities at 40 °C (up to ~3700 mPa·s at low shear), which decreased sharply with shear, indicating strong particle interactions. In contrast, MWCNT-based lubricants maintained moderate viscosities (90–365 mPa·s at 40 °C) with improved flowability due to nanotube alignment. At 100 °C, both systems showed viscosity reduction, stabilizing between 8 and 18 mPa·s, which favors pumpability in high-temperature applications. Tribological testing revealed distinct performance characteristics. CeO₂ lubricants showed slightly higher coefficients of friction (0.144–0.169) but excellent wear resistance, achieving the lowest wear rate of 1.66 × 10⁻⁶ mm³/N-m. MWCNT-based lubricants offered stable and lower CoF values (0.116–0.148) while also providing very low wear rates, with MCO6 achieving 1.62 × 10⁻⁶ mm³/N-m. However, ternary blends (C20T80 and M20T80) displayed moderate CoF but significantly higher wear rates (up to 2.92 × 10⁻⁵ mm³/N-m), suggesting that blending improves dispersion but weakens tribo-film stability. To complement the experimental findings, support vector regression (SVR), artificial neural networks (ANN), and AdaBoost algorithms were employed to predict key performance parameters based on compositional and thermal input data. The models demonstrated high prediction accuracy, validating the feasibility of AI-driven formulation screening. These results highlight the complementary potential of CeO₂ and MWCNT additives for high-performance bio-lubricant development and emphasize the role of machine learning in accelerating material optimization for sustainable lubrication systems. Full article

It is well known that nitrite is widely used in industrial and agricultural sectors as a preservative, corrosion inhibitor, and intermediate in chemical synthesis; consequently, nitrite residues are often present in food, water, and the environment as a result of meat curing, fertilizer use, and wastewater discharge. Despite having several applications, nitrite exerts toxic effects on human beings and aquatic life. Therefore, the monitoring of nitrite is of particular significance to avoid negative impacts on human health, the environment, and aquatic life. Previously, the electrochemical method has been extensively used for the development of nitrite sensors using various advanced electrode materials. Additionally, zinc oxide (ZnO), cerium oxide (CeO₂), titanium dioxide (TiO₂), copper oxide (CuO), iron oxides, nickel oxide (NiO), polymers, MXenes, reduced graphene oxide (rGO), carbon nanotubes (CNTs), graphitic carbon nitride (gCN), metal–organic frameworks (MOFs), and other composites have been utilized as electrocatalysts for the fabrication of nitrite electrochemical sensors. This review article provides an overview of the construction of nitrite sensors using advanced electrode materials. The electrochemical activities of the reported nitrite sensors are discussed. Furthermore, limitations and future perspectives regarding the determination of nitrite are discussed. Full article

Owing to the rapid advancements in optical and microsystem technologies, K9 glass is extensively utilized in the fabrication of high-precision optical components. Nevertheless, the intrinsic brittleness and elevated hardness of K9 glass, combined with the stringent demands of high-end optical systems for exceptional surface precision and minimal subsurface damage, present significant challenges for its chemical mechanical polishing (CMP) process. To overcome this challenge, we formulated a novel environmentally friendly and high-performance polishing slurry comprising cerium oxide (CeO₂), aluminum oxide (Al₂O₃), guanidine carbonate (GC), and sodium laureth-6 carboxylate (SL-6C). The incorporation of a minor proportion of high-hardness Al₂O₃ abrasive particles significantly enhanced the mechanical friction within the polishing slurry, thereby markedly increasing the MRR. The judicious addition of GC facilitated the formation of a hydration layer on the glass substrate. The surfactant SL-6C modulated the surface charge of the abrasive particles through electrostatic and coordination interactions, which improved particle dispersion and mitigated agglomeration. This effect minimized the risk of surface scratching and enhanced interfacial lubrication, consequently reducing the energy required for the detachment of the reaction layer. CMP findings demonstrated that utilizing an optimized slurry formulation comprising 1 wt% CeO₂, 0.05 wt% Al₂O₃, 0.2 wt% GC, and 0.2 wt% SL-6C yielded a surface roughness of K9 glass as low as 0.11 nm. Additionally, the MRR value reached 521.71 nm/min. Compared with the polishing slurry containing only CeO₂, the MRR increased by 7 times. The observed synergistic interactions among Al₂O₃, GC, SL-6C, and CeO₂ offered valuable insights for the advancement of high-performance CMP slurries. Full article

Numerous studies aimed to validate new shielding materials with the transition of medical radiation-shielding tools toward eco-friendly materials. In this study, we assessed the feasibility of ceramic composites, recently adopted in aerospace for internal shielding, as candidates for medical applications. Specifically, three types of ceramic composite mixtures were examined: bismuth oxide-based (Bi₂O₃), cerium oxide-based (CeO₂), and tantalum oxide-based (Ta₂O₅) ceramic composites. Two approaches—theoretical simulations and direct experiments—validated the performance under clinical conditions. Monte Carlo simulation results reveal that CeO₂, with its high linear attenuation coefficient, exhibits the strongest theoretical shielding. In terms of density measurements, Ta₂O₅ composite sheets yielded the highest density (3.318 g/cm³), followed by CeO₂ composites (3.228 g/cm³) and Bi₂O₃ composites (3.091 g/cm³). Although relatively slight differences in density were observed among the fabricated sheets, Ta₂O₅ composites tended to have slightly higher densities. However, Ta₂O₅ composites outperformed the other composites in direct clinical experiments. This discrepancy between the theoretical and experimental results highlights the influence of other factors, such as the energy characteristics of the materials and variations in the fabrication process. Overall, this study supports the development of eco-friendly radiation shields through theoretical and clinical validation. Full article

Cutaneous regeneration remains a major challenge in biomedicine, prompting the exploration of novel therapeutic agents such as cerium oxide nanoparticles (CeO₂ NPs, nanoceria). These nanoparticles exhibit multifaceted regenerative properties, including stimulation of metabolic and proliferative activity in keratinocytes, fibroblasts, and endothelial cells, potent antioxidant effects, immunomodulatory potential, and antimicrobial activity. Although numerous in vitro studies have characterized these properties, there is a critical need to evaluate nanoceria in more physiologically relevant in vivo settings, where dynamic biological conditions may significantly influence their efficacy. Furthermore, the therapeutic performance of CeO₂ NPs is highly dependent on the synthesis methods and formulation components (excipients and co-administered active substances). A review of existing in vivo studies investigating nanoceria-based formulations for wound healing addresses this gap. The authors found 25 relevant studies published as of September 2025 in major scientific databases, including PubMed, Scopus, the Cochrane Library, which provided data on the effectiveness of using cerium oxide nanoparticles as components of medical devices or wound dressings in accelerating wound healing in animal models. This analysis synthesizes evidence on nanoparticle efficacy, formulation strategies, and observed biological outcomes across animal models. These findings indicate that nanoceria formulations can accelerate wound closure and modulate the key phases of tissue repair, although the outcomes vary with particle characteristics and delivery systems. While nanoceria hold considerable promise for clinical wound management, standardized reporting of synthesis protocols and rigorous comparative in vivo studies are essential to translate their potential into reliable therapeutic applications. Full article

The pervasive discharge of synthetic dyes into aquatic ecosystems poses a significant threat due to their chemical stability, low biodegradability, and carcinogenicity. Conventional dye remediation methods—such as biological treatments, coagulation, and adsorption—have demonstrated limited efficiency and poor reusability, particularly against resilient azo dyes. Cerium oxide (CeO₂) nanoparticles have gained traction as photocatalysts owing to their redox-active surfaces and oxygen storage capabilities; however, issues like particle agglomeration and rapid charge recombination restrict their catalytic performance. To address these challenges, this study presents the novel synthesis of a graphene oxide–cerium oxide (GO-CeO₂) nanocomposite via a facile in situ hydrothermal approach, using graphite from lead pencils as a sustainable precursor. The composite was structurally characterized using UV–visible spectroscopy, XRD, FTIR, and TEM. The GO matrix not only facilitates uniform dispersion of CeO₂ nanoparticles but also enhances interfacial electron mobility and active site availability. The nanocomposite demonstrated exceptional photocatalytic degradation efficiencies for methyl orange (94%), methyl red (98%), congo red (96%), and 4-nitrophenol (85.6%) under sunlight irradiation, with first-order rate constants significantly exceeding those of pure CeO₂. Notably, GO–CeO₂ retained strong catalytic activity over four degradation cycles, confirming its recyclability and structural stability. Total organic carbon (TOC) analysis revealed 79% mineralization of methyl orange, outperforming CeO₂ (45%), indicating near-complete conversion into benign byproducts. This work contributes a scalable, low-cost, and highly active heterogeneous photocatalyst for wastewater treatment, combining green synthesis principles with improved photodegradation kinetics. Its modular architecture and reusability make it a promising candidate for future environmental remediation technologies and integrated photocatalytic systems. Full article

Background/Objectives: Glioblastoma, the most common primary tumor of the central nervous system, is characterized by high malignancy and poor prognosis. One of the main challenges in neurological disorders is to develop an effective treatment modality that can cross the blood–brain barrier. Nanoparticles are revolutionary for neurodegenerative diseases due to their targeted delivery and ability to overcome biological barriers. Cerium oxide (Ce₂O₃) nanoparticles are suitable for use as drug delivery systems. Methods: In our study, we investigated the anticancer mechanism using SN-38, lithium, and Ce₂O₃, a powerful agent used in GBM treatment. We evaluated their anticancer activities separately and in combination with U373 cell lines. GBM cell line U373 cells were cultured. Then, all groups except the control group were treated with different doses of SN-38 and lithium combination therapy with SN-38, lithium, and Ce₂O₃ combination therapy. The results were evaluated using MTT and ELISA tests. Results: When the results were examined, anticancer activity was detected at PTEN, AKT, mTOR, and BAX/Bcl-2 levels in the SN-38 + NPs 25 µg/mL + Lithium 50 µg/mL and SN-38 + NPs 50 µg/mL + Lithium 50 µg/mL dose groups. In addition, findings that inflammation markers were correlated with the apoptosis mechanism were obtained. Conclusion: This study is the first to report that combining lithium with SN-38 and NPs increased oxidative stress more than lithium with SN-38, leading glioblastoma cells to apoptosis and its potential anticancer activity. These results provide a basis for further investigation of its clinical application in cancer treatment. Full article

A novel highly sensitive voltammetric sensor based on a glassy carbon electrode (GCE) modified with a mixture of cerium and tin dioxide nanoparticles (NPs) as a sensing layer was developed. Surfactants of various nature (anionic sodium dodecyl sulfate, cationic N-cetylpyridinium bromide, and non-ionic Triton X-100, Brij^® 35, and Tween-80) were used as dispersive agents for NPs. Complete suppression and a significant decrease in the dye oxidation peak occurred in the case of Tween-80 and sodium dodecyl sulfate, respectively. CeO₂–SnO₂ NPs in Brij^® 35 gave the best response to Acid Yellow 3 caused by its adsorption at the electrode surface. Linear dynamic ranges of 0.50–7.5 and 7.5–25 mg L⁻¹ with a detection limit of 0.13 mg L⁻¹ of Acid Yellow 3 were achieved using differential pulse mode in Britton–Robinson buffer pH 5.0. Full article

Nickel–tungsten carbide (Ni/WC) multi-pass fused cladding layers with different cerium (IV) oxide (CeO₂) contents were applied to Cr12MoV cold work tool steel surfaces using the coaxial powder feeding method for laser cladding. Scanning electron microscopy, energy spectrum analysis, X-ray diffraction, and wear experiments were conducted to study how adding CeO₂ to change the properties of WC-reinforced Ni-base composite coatings in turn alters the microstructure and properties of Cr12MoV cold work tool steel. The results show that laser cladding is effective when the process parameters are as follows: a power of 1500 W, a 24 mm defocusing distance, a 6 mm/s scanning speed, a 5 mm spot diameter, and a powder delivery of 0.1 g/s. Laser-fused cladding coatings are mainly composed of dendrites, crystalline cells, strips, and bulk microstructures. The addition of CeO₂ is effective at improving the microstructure and morphology of the coating—the size and distribution of the reinforcing phase change very significantly, and the shape changes from irregular and lumpy to spherical. With a 2% CeO₂ content, the enhanced phase, now spherical and white, is more diffusely distributed in the tissue. The maximum microhardness of the composite-coated specimen after the addition of CeO₂ is about 986 HV, which is approximately 20% higher than the hardness of the composite coating with no CeO₂ added. Full article