Search Results (318)

The increasing use of cerium oxide nanoparticles (CeO₂-NPs) has raised concerns regarding their environmental fate and biological effects in soil–plant systems. This review uses cerium oxide nanoparticles (CeO₂-NPs) as a mechanistically well-characterized case study to examine relationships among dose, chemical speciation, and plant responses, with emphasis on Ce³⁺/Ce⁴⁺ redox cycling and condition-dependent, nanozyme-like activity. We discuss how particle size, surface charge, Ce³⁺/Ce⁴⁺ ratio, and coating interact with rhizosphere processes, including organic acid complexation, phosphate-mediated CePO₄ immobilization, and potentially microbially mediated transformation, to influence effective root-surface exposure. The resulting particulate, ionic, and secondary transformation-product pools affect root uptake, vascular transport, redox homeostasis, metabolism, and hormone-associated signaling. Major limitations include weak causal links between rhizosphere speciation and bioavailability, insufficient separation of particulate and ionic contributions, limited integration of multi-omics with speciation data, and uncertain extrapolation from hydroponic to soil systems. Standardized exposure protocols, integrated XANES, spICP-MS, and imaging workflows, and long-term soil studies are therefore required. Other rare-earth nanomaterials are discussed only briefly to define the material-specific boundaries of the CeO₂-centered framework. Full article

Green synthesis of metal oxide nanoparticles is a promising route to reduce toxic reagents and energy consumption while enabling biocompatible nanomaterials for biomedical use. In this work, cerium oxide (CeO₂) nanoparticles were synthesized using lemon juice and sucrose as bio-based chelating, capping and stabilizing agents. Three synthesis routes were designed by varying the use of lemon juice, sucrose, or their combination. The synthesized materials were characterized using thermal analysis (DSC—Differential Scanning Calorimetry and TGA—Thermogravimetric Analysis), X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Additionally, their antibacterial activity was assessed against Gram positive bacterium Staphylococcus aureus (S. aureus). Thermal analysis showed that heat treatment at 600 °C promotes high crystallinity, as evidenced by the development of sharp diffraction peaks associated with the cubic fluorite CeO₂ structure, and a dominant F_2g Raman mode at 463 cm⁻¹. SEM micrographs revealed nanometric particles and highlighted that combining lemon juice and sucrose effectively suppresses coalesced structures, yielding more homogeneous morphologies. Crystallite size calculations gave average sizes of 17.2 nm, with the lemon juice-only route producing the largest crystallites. Antibacterial tests revealed a clear dose-dependent inhibition of S. aureus, with marked inhibition of bacterial growth at concentrations ≥5 mg/mL and a plateau effect above 25 mg/mL. This study confirms the feasibility of using plant-based extracts as sustainable reagents for CeO₂ nanoparticle synthesis, with promising structural and biological performance for potential biomedical applications. Full article

The growing field of nanobiotechnology could provide an alternative platform for the development of new therapeutic agents. A potential means for achieving these goals are nanoparticles of rare-earth metals, for example, nanoceria. According to the results of numerous in vitro and in vivo studies, not only oxide forms of lanthanides can demonstrate a pharmacological effect. A promising nano-object for biomedical application is cerium phosphate, which exhibits both properties characteristic of cerium dioxide and its own unique properties, due to the diversity of morphology. However, at present, a unified methodological approach has not been formulated that would make it possible to formulate principles for obtaining a compound with specified properties. This review was conducted on using the international databases PubMed, PubChem, Scopus and Google Scholar, and included original studies and reviews. The literature describes the preparation of cerium phosphate nanoparticles by the hydrothermal, chemical precipitation, microwave, and sol–gel methods. It was established that reaction temperature, pH value of the medium, use of organic solvents, ratio of reagents, and precursors have a direct influence on the size, shape, and structure of the obtained nano-object, making it possible to synthesize nanospheres, nanorods, and nanoneedles by regulating these parameters. In addition, the strategy of obtaining nano-objects with specified properties can be implemented by using excipients of predominantly polymer nature. The use of auxiliary substances is capable both of exerting a stabilizing effect and improving adherence to the nanoscale range, and of influencing pharmacological activity. The literature describes the possibility of using cerium phosphate as a redox-active, regenerative, antibacterial, sunscreen, and antitumor agent. However, the insufficient amount of data on the toxicological profile, as well as the results of in vivo studies, remains a significant limitation for the introduction of cerium phosphate into clinical practice. Thus, the purpose of the present review is to identify patterns that make it possible to formulate recommendations for the synthesis of cerium phosphate with specified properties, to assess factors affecting its suitability for use in biomedicine, and to consider its prospects and limitations. Full article

This review presents recent results focused on immobilization of zeolites onto inexpensive aluminum substrate using plasma electrolytic oxidation (PEO) processing in various electrolyte solutions applying different electrical regimes. PEO is recognized as a useful technique for the formation of oxide coatings with photocatalytic properties on various metals and alloys. Thin film photocatalysts are more practical than powder/nanoparticle photocatalysts because the photocatalyst does not need to be filtered/separated after the wastewater degradation treatment, which is an expensive and time-consuming process. Addition of zeolites to supporting electrolyte solutions influences structural, morphological and chemical properties of formed oxide coatings. Furthermore, introduction of zeolites loaded with cerium through an ion-exchange procedure is investigated. It is shown that the addition of both parent zeolites and Ce-exchanged zeolites is beneficial for photocatalytic decomposition of model organic pollutant (methyl orange). The most promising results are obtained under ultra-low duty cycle electrical conditions with Ce-exchanged 13X zeolite added to the electrolyte, where about 60% of the model organic pollutant is decomposed during 6 h of treatment under simulated sunlight irradiation (16,000 lx) for 3 cm² surface area of sample exposed to irradiation. Full article

Cerium oxide nanoparticles (CeO₂NPs) possess unique physicochemical properties that make them promising compounds for medical and industrial applications. However, variations in synthesis methods, particle size, and surface characteristics may influence their potential toxicity. This study provides a comparative analysis of CeO₂NPs synthesized via three methods (citric, dextran, and uncoated modifications) to evaluate their toxicity, antioxidant mechanisms, and genoprotective potential using a panel of Escherichia coli-based lux-biosensors. Our data indicate that all of the tested CeO₂NPs exhibit high biocompatibility with no significant toxicity or genotoxicity at physiological concentrations (10⁻⁴–10⁻² M). The citrate-modified nanoparticles demonstrated pronounced catalase-mimetic activity, acting as the most effective scavengers against hydrogen peroxide. Conversely, the dextran-modified nanoparticles exhibited the highest antimutagenic potential, reducing dioxidine-induced DNA damage by over 56%. Thus, beyond establishing biocompatibility, this study highlights the potential of using specific CeO₂NP modifications for targeted therapy depending on the oxidative pathway involved. This suggests their potential for application as antioxidant and antimutagenic agents in both human and veterinary medicine. Full article

Red Amaranth (RA) Azo dye is a persistent pollutant in wastewater and stands as a toxicological risk, which has led to the development of effective methods for its removal and photocatalytic degradation. Therefore, CeO₂ nanoparticles were synthesized by a controlled precipitation method, and Ultraviolet-Visible (UV–Vis) analysis and Tauc plots yielded a band gap of ~3.24 eV. The CeO₂ nanoparticles showed the fluorite cubic phase, and nearly spherical particles with an average size of ~10 nm. Nitrogen physisorption revealed a type IV isotherm with a Brunauer–Emmett–Teller (BET) surface area of 85.27 m²·g⁻¹ and a total pore volume of 0.27 cm³·g⁻¹, indicating a mesoporous structure and high surface accessibility. The chemical behavior showed Ce and O, consistent with phase purity. Photocatalytic performance was evaluated in 20 ppm aqueous solution of RA under 365 nm UV irradiation (LED 100 W), with a temperature of ~20 °C and a 15 min dark adsorption step. Concentration decay was followed at λ_max = 520 nm by Lambert–Beer. The degradation efficiency η and pseudo-first-order kinetic were obtained from ln(C₀/C_t) vs. time. In addition, chemical oxygen demand (COD) tests were performed on RA solution before and after photodegradation, showing a COD reduction of ~85% (from 19.8 to 3 mg O₂·L⁻¹), which corroborates mineralization beyond chromophore bleaching. Under [C₀ = 20 mg·L⁻¹] and [m_cat = 1.0 g·L⁻¹], CeO₂ achieved [RA = 90% at 180 min, k = 0.0125 min⁻¹]. These results demonstrate that CeO₂ is an effective photocatalyst for RA degradation under UV-A irradiation, integrating adsorption, kinetic behavior, and mineralization performance into a coherent structure–property relationship. Full article

The hematite phase decorated with iron-doped cerium oxide nanoparticles (F@FC) was precipitated from cerium and iron oxalate intermediate products. The photocatalytic composite of graphitic carbon nitride (gCN) and F@FC was prepared by a simple method involving mixing the two components, followed by thermal treatment at 400 °C. According to electron microscopy, F@FC is composed of a submicron iron oxide (hematite) phase decorated with iron-doped cerium oxide nanoparticles deposited on gCN substrate. A hierarchically structured composite was observed instead of a simple mechanical mixture of α-Fe₂O₃, Fe-CeO₂, and gCN. To observe two types of degradation activity, photocatalytic and Photo-Fenton degradation activity, Rhodamine B (RhB) was applied as the model water pollutant. The influence of the amount of photocatalyst, the RhB concentration, the presence of cations and anions, the pH, and the effect of e⁻, h⁺, •OH, and •O₂⁻ scavenging reactants were studied. The Photo-Fenton degradation exhibited high efficiency across the entire tested pH range, whereas photocatalytic degradation showed comparable activity only at acidic pH. The F@FC-gCN composite catalyst exhibited a high degree of recyclability. The degradation pathways of photocatalytic and Photo-Fenton reactions were suggested by HPLC-MS analysis of the reaction products. A notable finding of this study was the observation that the green-yellow, fluorescent intermediate Rhodamine 110 was formed during the photocatalytic degradation of RhB. However, the high reactivity of the generated •OH radicals during Photo-Fenton degradation has been demonstrated to inhibit the formation of intermediate Rhodamine 110. Full article

This study presents a comprehensive comparative analysis of the performance, combustion, and emission characteristics of a single-cylinder, four-stroke spark-ignition engine fueled by commercial gasoline and raw biogas enhanced with cerium oxide (CeO₂) nanoparticles. Raw biogas containing 58% methane was tested without carbon dioxide removal to reflect practical rural applications, while CeO₂ nanoparticles were ultrasonically dispersed in the fuel to promote homogeneous suspension and catalytic activity. Experiments were conducted under wide-open and part-throttle conditions across a range of engine speeds, with simultaneous measurement of brake thermal efficiency, brake-specific fuel consumption, volumetric efficiency, in-cylinder pressure, heat release rate, combustion phasing, and regulated emissions. The results showed that while gasoline consistently outperformed biogas in torque and power due to its higher heating value and flame speed, the addition of CeO₂ significantly reduced the performance gap. For the biogas mode, CeO₂ addition increased brake thermal efficiency by up to 5%, lowered brake-specific fuel consumption by up to 8%, and shifted the start of main combustion to earlier crank angles, indicating faster and more complete combustion, particularly at high loads where higher temperatures activate CeO₂’s catalytic behavior. Emission analysis revealed that CeO₂-blended biogas reduced carbon monoxide emissions by approximately 25% and unburned hydrocarbons by up to 55% compared with gasoline, while nitrogen oxide emissions were consistently 15–22% lower. These reductions were observed across both wide-open and part-throttle conditions, confirming improved combustion completeness and lower peak flame temperatures. These improvements are attributed to CeO₂’s oxygen-storage capability, catalytic oxidation activity, and enhanced thermal conductivity, which collectively strengthen combustion completeness and cyclic stability. The findings demonstrate that nanoparticle-enhanced biogas can substantially improve the environmental and operational viability of spark-ignition engines, offering a practical pathway for integrating renewable gaseous fuels into existing transportation systems. Full article

Zinc-based coatings are insufficient as surface coatings; they corrode rapidly and can cause long-term damage to subsea pipelines and other instruments. Therefore, this research was undertaken by manufacturing a sacrificial nano-reinforced Zn coating combined with additives via electrodeposition onto a mild steel S235 substrate, which provides excellent corrosion resistance under severe marine conditions. The electrodeposited coatings were characterized using SEM/EDS and XRD, revealing the effective incorporation of cerium oxide nanoparticles and high-quality graphene (Gr) in the zinc matrix. Vickers microhardness measurements, mechanical resilience, and surface roughness of the Zn-CeO₂-Gr coating showed an inverse correlation between improved microhardness (+65.85%) and mechanical resilience (+31.49%), while surface roughness decreased (−81.48%) compared to pure zinc electrodeposited coatings. These characteristics indicate grain refinement and greater reliability under mechanical stress. Electrochemical impedance spectroscopy (EIS) and DC polarization measurements indicate a significant improvement in corrosion resistance compared to pure zinc, due to the synergistic effect between graphene and cerium oxide nanoparticles, which reduces the cathodic activity of the surface. These findings offer promising applications for cutting-edge materials in saline environments. Full article

This study evaluates the effects of Al₂O₃ and CeO₂ nanoparticles as additives to standard diesel and biodiesel fuels on the combustion and emissions characteristics of a CR diesel engine with split injection (pilot and main injections). Three nanoparticle dosing levels (50 ppm, 100 ppm, and 150 ppm) were compared with undoped standard diesel and biodiesel fuels. The results showed that the presence of both Al₂O₃ and CeO₂ in biodiesel increased the ignition delay of the pilot fuel by about 8.0% at low load and about 3.5% at high load. The addition of both nanoparticles to diesel and biodiesel fuels had an insignificant effect on the main injection fuel’s ignition delay, MBF50 position and combustion duration. The thermal efficiency was up to 1.0% lower. Al₂O₃ additive in diesel had no significant effect on NO_x emissions. CO emissions were higher by 4.4–7.5% in most cases. The Al₂O₃ additive in biodiesel reduced NO_x emissions by an average of 38%, 17.1%, and 9.4% at low, medium, and high engine loads, respectively. The reduction in CO emissions averaged 15%. The addition of CeO₂ nanoparticles to diesel fuel reduced NO_x emissions by 22.5%, 8.5%, and 3.1% on average across the corresponding load ranges. When the engine was operated on CeO₂-doped biodiesel, NO_x emissions were lower by an average of 25.7%, 9.6%, and 2.5% at low, medium, and high loads, respectively. Adding CeO₂ nanoparticles to diesel fuel increased CO emissions, whereas adding them to biodiesel significantly reduced CO emissions. Full article

Mesoporous bioactive glass nanoparticles (MBGNs) are promising for bone tissue engineering; however, surgical site infection and oxidative stress often compromise regeneration. To address this, MBGNs co-doped with cerium (Ce), zinc (Zn), and strontium (Sr) were synthesized using a microemulsion-assisted sol-gel route (xCe-yZn-Sr-MBGNs; x = 0, 1, 2; y = 0, 0.5, 1). The resulting spherical nanoparticles (150–200 nm) exhibited a mesoporous structure with a specific surface area of (~340–425 m²/g), sustained ion release, and apatite formation in simulated body fluid. In vitro evaluations with MC3T3-E1 pre-osteoblasts demonstrated dose-dependent cytocompatibility, specifically in the co-doped formulations; however, higher Ce concentrations (2Ce-yZn-Sr-MBGNs) reduced viability following prolonged exposure. Crucially, the 1Ce-1Zn-Sr-MBGNs significantly enhanced osteogenic differentiation, as evidenced by a two-fold increase in osteogenic marker gene expression and a ~45% increase in calcium mineral deposition compared to undoped MBGNs within 14 days. Moreover, these particles accelerated cell migration, achieving ~70% scratch-wound closure within 24 h. Furthermore, 1Ce-1Zn-Sr-MBGNs displayed strong radical scavenging capacity and potent antibacterial activity against S. aureus and P. aeruginosa. These findings indicated that 1Ce-1Zn-Sr-MBGNs exhibited multiple therapeutic effects, including antibacterial, radical-scavenging, and osteogenic effects. By optimizing dopant ratios, these multifunctional nanomaterials emerge as promising candidates for next-generation bone grafts or implant coatings. Within the scope of this study, they demonstrated the capacity to simultaneously address three critical challenges in bone healing: controlling infection, mitigating oxidative stress, and promoting mineralized tissue formation. While these in vitro results provide a robust foundation, further in vivo validation is warranted to confirm their efficacy within complex physiological environments. Full article

α-Fe_2−4xZ_3xO₃ (Z = Ce, Ru) nanoparticles were synthesized via a conventional solid-state reaction route. X-Ray diffraction analysis confirmed that all compositions crystallize in the single-phase hexagonal hematite (α-Fe₂O₃) structure, with no detectable secondary phases. Cerium substitution resulted in a pronounced reduction in crystallite size accompanied by a progressive narrowing of the optical band gap, which decreased to approximately 1.73 eV at higher Ce contents. The optical properties were further investigated through absorption coefficient, optical transmittance, and complex refractive index analyses, revealing that cerium-doped hematite exhibits enhanced light-harvesting capability, highlighting its strong potential for optoelectronic and solar-energy conversion applications. Magnetic hysteresis measurements on α-Fe_2−4xRu_3xO₃ samples showed a systematic increase in both coercive field (H_c) and remanent magnetization (M_r) with increasing Ru concentration. This magnetic hardening behavior is attributed to strengthened magnetocrystalline and shape anisotropy induced by Ru incorporation into the hematite lattice. Mössbauer spectroscopy confirmed the presence of Fe³⁺ and Ru⁴⁺ species, providing valuable insight into the oxidation states and local magnetic environments within the corundum-type structure. Full article

The conversion of lignocellulosic biomass (LCB) into biofuels is hindered by its inherent resistance and the drawbacks of conventional pretreatment, which include high cost, intensive energy use, and inhibitor formation. Here, we present a novel, one-pot bioconversion process that bypasses pretreatment by integrating cerium-doped iron oxide nanoparticles (CeFeO₄NPs) with a specialized enzyme system. The system utilizes enzyme supernatant from Penicillium janthinellum mutant EU-30, a strain developed via chemical–physical mutagenesis, which exhibits stable hemicellulase activity and a 25–30% increase in cellulase activity. The integrated approach effectively saccharified raw sugarcane bagasse (SB) within 24 h, generating the highest yields of 12.8 ± 0.5 g/L glucose and 11.54 ± 0.5 g/L xylose compared to other substrates tested. Subsequent fermentation with Saccharomyces cerevisiae yielded 13.47 g/L ethanol (1.21 g/L/h productivity) and demonstrated concurrent consumption of both hexose and pentose sugars. We propose that residual CeFe₃O₄NPs in the hydrolysate mitigate carbon catabolite inhibition, thereby increasing xylose utilization. This was attributed to the residual CeFe₃O₄NPs in the hydrolysate, which are thought to upregulate xylose-metabolism-related genes in S. cerevisiae, thereby alleviating carbon catabolite inhibition. This method offers a streamlined, economical, and sustainable platform for producing carbon-neutral bioethanol from agricultural waste, eliminating costly pretreatment and simplifying downstream processing. Full article

Biofilm-associated infections remain a major barrier to wound healing, implant integration, and chronic infection management. Rare-earth oxides (REOs) have emerged as promising antibiofilm materials, though their mechanisms, limitations, and translational potential are still being defined. Cerium oxide (CeO₂) serves as the benchmark due to its redox adaptability, oxygen-vacancy-driven catalytic activity, and host compatibility. In contrast, non-ceria REOs show antibiofilm effects under more restricted conditions, often requiring surface functionalization, composite architectures, or hybrid organic–inorganic interfaces—such as polyphenol coatings or hydroxyapatite-based composites—to achieve comparable activity. Across systems, biofilm control arises not from bactericidal potency but from matrix-level mechanisms including extracellular polymeric substance (EPS) destabilization, extracellular DNA (eDNA) sequestration, redox modulation, and quorum-sensing interference. Preclinical and near-clinical evidence, particularly in chronic wound models, supports the translational relevance of these mechanisms, though the evidence base remains preliminary. This review synthesizes mechanistic data across cerium-, samarium-, lanthanum-, and strontium-based systems to establish a unified framework for REO-mediated biofilm disruption. REOs are positioned as biofilm-modulating platforms that complement antibiotics, enhance healing, and improve outcomes. Design rules emphasize controlled redox activity, targeted coordination chemistry, functional surface engineering, and host-compatible performance, alongside regulatory and manufacturing guidance for future development. Full article

Background: Diabetes mellitus is common and associated with numerous complications including diabetic foot ulcers (DFU), which affect a third of patients and are associated with high morbidity and mortality. There are limited pharmacologic treatment options available with mixed efficacy. We have developed a novel therapeutic targeting inflammation and oxidative stress by conjugating microRNA-146a to cerium oxide nanoparticles to create CNP-miR146a and have found that injectable CNP-miR146a is associated with improved wound healing in a diabetic murine model. We hypothesized that a topical formulation of CNP-miR146a would be associated with equivalent improvements in wound healing. Methods: Release tests of CNP conjugated to fluorescein isothiocyanate were performed to determine the optimal gel base for sustained release. Diabetic (db/db) mice were cutaneously wounded and treated with topical CNP-miR146a, empty gel, injectable CNP-miR146a, or injectable phosphate-buffered saline (PBS). Wound healing over time was compared between groups. Histological samples were collected and analyzed for CD45 and CD31 positivity at multiple timepoints. Results: CNP-miR146a in a topical pluronic lecithin organogel (PLO) base was associated with significantly improved wound healing compared to empty gel or injected PBS and equivalent to injected CNP-miR146a. Treatment with CNP-miR146a was also associated with decreased CD45 positivity and increased CD31 positivity, suggesting decreased inflammation and improved angiogenesis. Conclusions: Topical delivery of CNP-miR46a in a PLO base holds significant promise as a potential therapeutic for DFU and may improve patient compliance due to ease of delivery. Full article