Auto-catalytic ceria nanoparticles offer neuroprotection to adult rat spinal cord neurons

Modified Ce/Zr-MOF Nanoparticles Loaded with Curcumin for Alzheimer's Disease via Multifunctional Modulation

Introduction

Alzheimer's disease (AD), a neurodegenerative condition, stands as the most prevalent form of dementia. Its complex pathological mechanisms and the formidable blood-brain barrier (BBB) pose significant challenges to current treatment approaches. Oxidative stress is recognized as a central factor in AD, underscoring the importance of antioxidative strategies in its treatment. In this study, we developed a novel brain-targeted nanoparticle, Ce/Zr-MOF@Cur-Lf, for AD therapy.

Methods

Layer-by-layer self-assembly technology was used to prepare Ce/Zr-MOF@Cur-Lf. In addition, the effect on the intracellular reactive oxygen species level, the uptake effect by PC12 and bEnd.3 cells and the in vitro BBB permeation effect were investigated. Finally, the mouse AD model was established by intrahippocampal injection of Aβ1-42, and the in vivo biodistribution, AD therapeutic effect and biosafety of the nanoparticles were researched at the animal level.

Results

As anticipated, Ce/Zr-MOF@Cur-Lf demonstrated efficient BBB penetration and uptake by PC12 cells, leading to attenuation of H2O2-induced oxidative damage. Moreover, intravenous administration of Ce/Zr-MOF@Cur-Lf resulted in rapid brain access and improvement of various pathological features of AD, including neuronal damage, amyloid-β deposition, dysregulated central cholinergic system, oxidative stress, and neuroinflammation.

Conclusion

Overall, Ce/Zr-MOF@Cur-Lf represents a promising approach for precise brain targeting and multi-target mechanisms in AD therapy, potentially serving as a viable option for future clinical treatment.

In Situ Symbiosis of Cerium Oxide Nanophase for Enhancing the Oxygen Electrocatalysis Performance of Single-Atom Fe─N─C Catalyst with Prolonged Stability for Zinc-Air Batteries

The Fenton reaction, induced by the H2O2 formed during the oxygen reduction reaction (ORR) process leads to significant dissolution of Fe, resulting in unsatisfactory stability of the iron-nitrogen-doped carbon catalysts (Fe-NC). In this study, a strategy is proposed to improve the ORR catalytic activity while eliminating the effect of H2O2 by introducing CeO2 nanoparticles. Transmission electron microscopy and subsequent characterizations reveal that CeO2 nanoparticles are uniformly distributed on the carbon substrate, with atomically dispersed Fe single-atom catalysts (SACs) adjacent to them. CeO2@Fe-NC achieves a half-wave potential of 0.89 V and a limiting current density of 6.2 mA cm-2, which significantly outperforms Fe-NC and commercial Pt/C. CeO2@Fe-NC also shows a half-wave potential loss of only 1% after 10 000 CV cycles, which is better than that of Fe-NC (7%). Further, H2O2 elimination experiments show that the introduction of CeO2 significantly accelerate the decomposition of H2O2. In situ Raman spectroscopy results suggest that CeO2@Fe-NC significantly facilitates the formation of ORR intermediates compared with Fe-NC. The Zn-air batteries utilizing CeO2@Fe-NC cathodes exhibit satisfactory peak power density and open-circuit voltage. Furthermore, theoretical calculations show that the introduction of CeO2 enhances the ORR activity of Fe-NC SAC. This study provides insights for optimizing SAC-based electrocatalysts with high activity and stability.

Bifunctional Tb(III)-modified Ce-MOF nanoprobe for colorimetric and fluorescence sensing of α-glucosidase activity

α-Glucosidase, which directly involves in the metabolism of starch and glycogen and causes an increase in blood sugar level, is the major target enzyme for the precaution and therapy of type II diabetes. Based on the previous work, we adopted a post-synthetic modification method to encapsulate Tb3+ into Ce-MOF nanozyme which owned mixed valence states. Tb@Ce-MOF displayed induced luminescence characteristic and exceptional oxidase-like activity that could oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue ox-TMB. α-Glucosidase can hydrolyze the substrate l-ascorbic acid-2-O-α-d-glucopyranosyl (AAG) to generate ascorbic acid (AA), which could increase the Ce3+/Ce4+ redox valence mode in Tb@Ce-MOF, leading to the inhibition of the allochroic reaction of TMB and the decreased absorption of ox-TMB at 652 nm. The energy transfer (EnT) process from Ce3+ to Tb3+ will enhance due to the increased Ce3+/Ce4+ mode in Tb@Ce-MOF, which will result in an enhanced fluorescence signal of Tb@Ce-MOF at 550 nm. But the addition of inhibitor acarbose will inhibit the above process. We have constructed a dual-mode detection platform of α-glucosidase and its inhibitor via colorimetric and fluorometric method. The linear range of α-glucosidase were 0.01-0.5 U/mL (colorimetric mode) and 0.8-1.5 U/mL (fluorometric mode), respectively, with a detection limit as low as 0.0018 U/mL. Furthermore, our approach was also successfully employed to the analysis of α-glucosidase in serum samples.

Oral enzyme-responsive nanoprobes for targeted theranostics of inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a progressive and debilitating inflammatory disease of the gastrointestinal tract (GIT). Despite recent advances, precise treatment and noninvasive monitoring remain challenging.

METHODS

Herein, we developed orally-administered, colitis-targeting and hyaluronic acid (HA)-modified, core-shell curcumin (Cur)- and cerium oxide (CeO2)-loaded nanoprobes (Cur@PC-HA/CeO2 NPs) for computed tomography (CT) imaging-guided treatment and monitoring of IBD in living mice.

RESULTS

Following oral administration, high-molecular-weight HA maintains integrity with little absorption in the upper GIT, and then actively accumulates at local colitis sites owing to its colitis-targeting ability, leading to specific CT enhancement lasting for 24 h. The retained NPs are further degraded by hyaluronidase in the colon to release Cur and CeO2, thereby exerting anti-inflammatory and antioxidant effects. Combined with the ability of NPs to regulate intestinal flora, the oral NPs result in substantial relief in symptoms. Following multiple treatments, the gradually decreasing range of the colon with high CT attenuation correlates with the change in the clinical biomarkers, indicating the feasibility of treatment response and remission.

CONCLUSION

This study provides a proof-of-concept for the design of a novel theranostic integration strategy for concomitant IBD treatment and the real-time monitoring of treatment responses.

Two decades of ceria nanoparticle research: structure, properties and emerging applications

Cerium oxide nanoparticles (CeNPs) are versatile materials with unique and unusual properties that vary depending on their surface chemistry, size, shape, coating, oxidation states, crystallinity, dopant, and structural and surface defects. This review encompasses advances made over the past twenty years in the development of CeNPs and ceria-based nanostructures, the structural determinants affecting their activity, and translation of these distinct features into applications. The two oxidation states of nanosized CeNPs (Ce3+/Ce4+) coexisting at the nanoscale level facilitate the formation of oxygen vacancies and defect states, which confer extremely high reactivity and oxygen buffering capacity and the ability to act as catalysts for oxidation and reduction reactions. However, the method of synthesis, surface functionalization, surface coating and defects are important factors in determining their properties. This review highlights key properties of CeNPs, their synthesis, interactions, and reaction pathways and provides examples of emerging applications. Due to their unique properties, CeNPs have become quintessential candidates for catalysis, chemical mechanical planarization (CMP), sensing, biomedical applications, and environmental remediation, with tremendous potential to create novel products and translational innovations in a wide range of industries. This review highlights the timely relevance and the transformative potential of these materials in addressing societal challenges and driving technological advancements across these fields.

Electrospun Composites of Chitosan with Cerium Oxide Nanoparticles for Wound Healing Applications: Characterization and Biocompatibility Evaluation In Vitro and In Vivo

Cerium oxide nanoparticles (CeONPs), as part of tissue regeneration matrices, can protect cells from reactive oxygen species and oxidative stress. In addition, they can influence the properties of the scaffold, including its electrospinnability and mechanical strength. In this work, we prepared electrospun fiber mats from a chitosan and polyethylene oxide blend (CS-PEO) with the addition of ceria nanoparticles (CS-PEO-CeONP). The addition of CeONPs resulted in a smaller fiber diameter and higher swelling compared to CS-PEO fiber mats. CeONP-modified fiber mats also had a higher Young's modulus due to the reinforcing effect of the nanoparticles. Both mats had comparable adhesion and cytocompatibility to mesenchymal stem cells, which had a more rounded morphology on CS-PEO-CeONP compared to elongated cells on the CS-PEO mats. Biocompatibility in an in vivo rat model showed no acute toxicity, no septic or allergic inflammation, and no rough scar tissue formation. The degradation of both mats passed the stage of matrix swelling. CS-PEO-CeONP showed significantly slower biodegradation, with most of the matrix remaining in the tissue after 90 days. The reactive inflammation was aseptic in nature with the involvement of multinucleated foreign-body type giant cells and was significantly reduced by day 90. CeONPs induced the formation of the implant's connective tissue capsule. Thus, the introduction of CeONPs influenced the physicochemical properties and biological activity of CS-PEO nanofiber mats.

A neoteric antibacterial ceria-silver nanozyme for abiotic surfaces

Community-associated and hospital-acquired infections caused by bacteria continue to yield major global challenges to human health. Bacterial contamination on abiotic surfaces is largely spread via high-touch surfaces and contemporary standard disinfection practices show limited efficacy, resulting in unsatisfactory therapeutic outcomes. New strategies that offer non-specific and broad protection are urgently needed. Herein, we report our novel ceria-silver nanozyme engineered at a molar ratio of 5:1 and with a higher trivalent (Ce3+) surface fraction. Our results reveal potent levels of surface catalytic activity on both wet and dry surfaces, with rapid, and complete eradication of Pseudomonas aeruginosa, Staphylococcus aureus, and methicillin resistant S. aureus, in both planktonic and biofilm form. Preferential electrostatic adherence of anionic bacteria to the cationic nanozyme surface leads to a catastrophic loss in both aerobic and anaerobic respiration, DNA damage, osmodysregulation, and finally, programmed bacterial lysis. Our data reveal several unique mechanistic avenues of synergistic ceria-Ag efficacy. Ag potentially increases the presence of Ce3+ sites at the ceria-Ag interface, thereby facilitating the formation of harmful H2O2, followed by likely permeation across the cell wall. Further, a weakened Ag-induced Ce-O bond may drive electron transfer from the Ec band to O2, thereby further facilitating the selective reduction of O2 toward H2O2 formation. Ag destabilizes the surface adsorption of molecular H2O2, potentially leading to higher concentrations of free H2O2 adjacent to bacteria. To this end, our results show that H2O2 and/or NO/NO2-/NO3- are the key liberators of antibacterial activity, with a limited immediate role being offered by nanozyme-induced ROS including O2•- and OH•, and likely other light-activated radicals. A mini-pilot proof-of-concept study performed in a pediatric dental clinic setting confirms residual, and continual nanozyme antibacterial efficacy over a 28-day period. These findings open a new approach to alleviate infections caused by bacteria for use on high-touch hard surfaces.

Recent Progress in Anti-Tumor Nanodrugs Based on Tumor Microenvironment Redox Regulation

The growth state of tumor cells is strictly affected by the specific abnormal redox status of the tumor microenvironment (TME). Moreover, redox reactions at the biological level are also central and fundamental to essential energy metabolism reactions in tumors. Accordingly, anti-tumor nanodrugs targeting the disruption of this abnormal redox homeostasis have become one of the hot spots in the field of nanodrugs research due to the effectiveness of TME modulation and anti-tumor efficiency mediated by redox interference. This review discusses the latest research results of nanodrugs in anti-tumor therapy, which regulate the levels of oxidants or reductants in TME through a variety of therapeutic strategies, ultimately breaking the original "stable" redox state of the TME and promoting tumor cell death. With the gradual deepening of study on the redox state of TME and the vigorous development of nanomaterials, it is expected that more anti-tumor nano drugs based on tumor redox microenvironment regulation will be designed and even applied clinically.

Cerium oxide nanoparticles in wound care: a review of mechanisms and therapeutic applications

Skin wound healing is a complex and tightly regulated process. The frequent occurrence and reoccurrence of acute and chronic wounds cause significant skin damage to patients and impose socioeconomic burdens. Therefore, there is an urgent requirement to promote interdisciplinary development in the fields of material science and medicine to investigate novel mechanisms for wound healing. Cerium oxide nanoparticles (CeO2 NPs) are a type of nanomaterials that possess distinct properties and have broad application prospects. They are recognized for their capabilities in enhancing wound closure, minimizing scarring, mitigating inflammation, and exerting antibacterial effects, which has led to their prominence in wound care research. In this paper, the distinctive physicochemical properties of CeO2 NPs and their most recent synthesis approaches are discussed. It further investigates the therapeutic mechanisms of CeO2 NPs in the process of wound healing. Following that, this review critically examines previous studies focusing on the effects of CeO2 NPs on wound healing. Finally, it suggests the potential application of cerium oxide as an innovative nanomaterial in diverse fields and discusses its prospects for future advancements.

Ceria nanoparticles: biomedical applications and toxicity

Ceria nanoparticles (CeO2 NPs) have become popular materials in biomedical and industrial fields due to their potential applications in anti-oxidation, cancer therapy, photocatalytic degradation of pollutants, sensors, etc. Many methods, including gas phase, solid phase, liquid phase, and the newly proposed green synthesis method, have been reported for the synthesis of CeO2 NPs. Due to the wide application of CeO2 NPs, concerns about their adverse impacts on human health have been raised. This review covers recent studies on the biomedical applications of CeO2 NPs, including their use in the treatment of various diseases (e.‍g., Alzheimer's disease, ischemic stroke, retinal damage, chronic inflammation, and cancer). CeO2 NP toxicity is discussed in terms of the different systems of the human body (e.‍g., cytotoxicity, genotoxicity, respiratory toxicity, neurotoxicity, and hepatotoxicity). This comprehensive review covers both fundamental discoveries and exploratory progress in CeO2 NP research that may lead to practical developments in the future.

Cerium oxide nanoparticles as a new neuroprotective agent to promote functional recovery in a rat model of sciatic nerve crush injury

BACKGROUND

Peripheral nerve injury is a common clinical disorder. The aim of the present study was to investigate the role of cerium oxide nanoparticles on axonal regeneration and functional recovery of the sciatic nerve after a crush injury in the rat model.

METHOD

A total of 40 adult male Wistar rats were divided into four groups. The animals underwent deep anesthesia. Afterward, the right sciatic nerve of rats was exposed and crushed. In two experimental groups, rats were treated intraperitoneally with cerium oxide nanoparticles at the dosage of 20 or 80 mg/kg daily for 1 week. The control group was given a vehicle. Then, during the nerve regeneration motor and sensory function recovery tests, histomorphometric evaluations, histological assessment of gastrocnemius muscle, and gastrocnemius muscle wet weights tests were performed.

RESULTS

Results demonstrated that the rate of nerve regeneration increased with the administration of cerium oxide nanoparticle in high doses. Also, the morphometric analysis showed that the number of myelinated fibers and myelin sheath thicknesses was significantly greater in the cerium oxide nanoparticle group versus the control group. Other parameters also improved in the cerium oxide nanoparticle treatment groups compared with the control group.

CONCLUSION

These data indicate that this nanoparticle has therapeutic potential and can be considered as a new treatment for nervous system regeneration.

Cerium Oxide Catalyzed Disproportionation of Hydrogen Peroxide: A Closer Look at the Reaction Intermediate

Cerium oxide nanoparticles (CNPs) have recently gained increasing interest as redox enzyme-mimetics to scavenge the intracellular excess of reactive oxygen species, including hydrogen peroxide (H2 O2 ). Despite the extensive exploration, there remains a notable discrepancy regarding the interpretation of observed redshift of UV-Visible spectroscopy due to H2 O2 addition and the catalase-mimicking mechanism of CNPs. To address this question, we investigated the reaction mechanism by taking a closer look at the reaction intermediate during the catalase mimicking reaction. In this study, we present evidence demonstrating that in aqueous solutions, H2 O2 adsorption at CNP surface triggers the formation of stable intermediates known as cerium-peroxo (Ce-O2 2- ) and/or cerium-hydroperoxo (Ce-OOH- ) complexes as resolved by Raman scattering and UV-Visible spectroscopy. Polymer coating presents steric hinderance for H2 O2 accessibility to the solid-liquid interface limiting further intermediate formation. We demonstrate in depth that the catalytic reactivity of CNPs in the H2 O2 disproportionation reaction increases with the Ce(III)-fraction and decreases in the presence of polymer coatings. The developed approach using UV-Visible spectroscopy for the characterization of the surface peroxide species can potentially serve as a foundation for determining the catalytic reactivity of CNPs in the disproportionation of H2 O2 .

Safety assessment and gastrointestinal retention of orally administered cerium oxide nanoparticles in rats

Cerium oxide nanoparticles (CeO2 NPs, NM-212) are well-known for their catalytic properties and antioxidant potential, and have many applications in various industries, drug delivery, and cosmetic formulations. CeO2 NPs exhibit strong antimicrobial activity and can be used to efficiently remove pathogens from different environments. However, knowledge of the toxicological evaluation of CeO2 NPs is too limited to support their safe use. In this study, CeO2 NPs were orally administered to Sprague Dawley rats for 13 weeks at the doses of 0, 10, 100, and 1000 mg/kg bw/day, followed by a four week recovery period. The hematology values for the absolute and relative reticulocyte counts in male rats treated with 1000 mg/kg bw/day CeO2 NPs were lower than those in control rats. The clinical chemistry values for sodium and chloride in the treated male rat groups (100 and 1000 mg/kg/day) and total protein and calcium in the treated female rat groups (100 mg/kg/day) were higher than those in the control groups. However, these changes were not consistent in both sexes, and no abnormalities were found in the corresponding pathological findings. The results showed no adverse effects on any of the parameters assessed. CeO2 NPs accumulated in the jejunum, colon, and stomach wall of rats administered 1000 mg/kg CeO2 NPs for 90 days. However, these changes were not abnormal in the corresponding histopathological and immunohistochemical examinations. Therefore, 1000 mg/kg bw/day may be considered the "no observed adverse effect level" of CeO2 NPs (NM-212) in male and female SD rats under the present experimental conditions.

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.

Advanced Biological Applications of Cerium Oxide Nanozymes in Disease Related to Oxidative Damage

Due to their excellent catalytic activities, cerium oxide nanoparticles have promise as biological nanoenzymes. A redox reaction occurs between Ce3+ ions and Ce4+ ions during which they undergo conversion by acquiring or losing electrons as well as forming oxygen vacancies (or defects) in the lattice structure, which can act as antioxidant enzymes and simulate various enzyme activities. A number of cerium oxide nanoparticles have been engineered with multienzyme activities, including catalase, superoxide oxidase, peroxidase, and oxidase mimetic properties. Cerium oxide nanoparticles have nitric oxide radical clearing and radical scavenging properties and have been widely used in a number of fields of biology, including biomedicine, disease diagnosis, and treatment. This review provides a comprehensive introduction to the catalytic mechanisms and multiple enzyme activities of cerium oxide nanoparticles, along with their potential applications in the treatment of diseases of the brain, bones, nerves, and blood vessels.

Breaking boundaries: Artificial intelligence for pesticide detection and eco-friendly degradation

Pesticides are extensively used agrochemicals across the world to control pest populations. However, irrational application of pesticides leads to contamination of various components of the environment, like air, soil, water, and vegetation, all of which build up significant levels of pesticide residues. Further, these environmental contaminants fuel objectionable human toxicity and impose a greater risk to the ecosystem. Therefore, search of methodologies having potential to detect and degrade pesticides in different environmental media is currently receiving profound global attention. Beyond the conventional approaches, Artificial Intelligence (AI) coupled with machine learning and artificial neural networks are rapidly growing branches of science that enable quick data analysis and precise detection of pesticides in various environmental components. Interestingly, nanoparticle (NP)-mediated detection and degradation of pesticides could be linked to AI algorithms to achieve superior performance. NP-based sensors stand out for their operational simplicity as well as their high sensitivity and low detection limits when compared to conventional, time-consuming spectrophotometric assays. NPs coated with fluorophores or conjugated with antibody or enzyme-anchored sensors can be used through Surface-Enhanced Raman Spectrometry, fluorescence, or chemiluminescence methodologies for selective and more precise detection of pesticides. Moreover, NPs assist in the photocatalytic breakdown of various organic and inorganic pesticides. Here, AI models are ideal means to identify, classify, characterize, and even predict the data of pesticides obtained through NP sensors. The present study aims to discuss the environmental contamination and negative impacts of pesticides on the ecosystem. The article also elaborates the AI and NP-assisted approaches for detecting and degrading a wide range of pesticide residues in various environmental and agrecultural sources including fruits and vegetables. Finally, the prevailing limitations and future goals of AI-NP-assisted techniques have also been dissected.

NOS-like activity of CeO2 nanozymes contributes to diminishing the vascular plaques

Ceria nanoparticles (CeO2NPs) exhibit great potential in cardiovascular disease and nonalcoholic fatty liver disease due to its excellent antioxidant capacity. However, the profitable effect of CeO2NPs on many diseases is almost all attributed to the regulation of ROS. Apart from the general antioxidant function, there seems to be no more distinct mechanism to reflect its unique multi-disease improvement effect. Here, we for the first time reveal a new discovery of CeO2NPs in mimicking nitric oxide synthase (NOS) by catalyzing L-arginine (L-Arg) to produce nitric oxide (NO) or the derivatives. NOS-like activity of CeO2NPs is original and associated with multiple factors like substrate concentration, pH, temperature and time, etc. where oxygen vacancy ratio plays a more critical role. Meanwhile, NOS-like activity of CeO2NPs successfully elevates NO secretion in endothelial cells and macrophages without expanding eNOS/iNOS expression. Importantly, NOS-like activity of CeO2NPs and the responsive endogenous NO promote the re-distribution of blood lipids and stabilize eNOS expression but suppress iNOS, thus collectively alleviate the accumulation of vascular plaque. Altogether, we provide a new angle of view to survey the outstanding potential of CeO2NPs, apart from the inevitable antioxidant capacity, the covert but possible and more critical NOS-like enzymatic activity is more noteworthy.

Radioprotective Potency of Nanoceria

Cancer presents a significant medical challenge that requires effective management. Current cancer treatment options, such as chemotherapy, targeted therapy, radiotherapy, and immunotherapy, have limitations in terms of their efficacy and the potential harm they can cause to normal tissues. In response, researchers have been focusing on developing adjuvants that can enhance tumor responses while minimizing damage to healthy tissues. Among the promising options, nanoceria (NC), a type of nanoparticle composed of cerium oxide, has garnered attention for its potential to improve various cancer treatment regimens. Nanoceria has demonstrated its ability to exhibit toxicity towards cancer cells, inhibit invasion, and sensitize cancer cells to both radiation therapy and chemotherapy. The remarkable aspect is that nanoceria show minimal toxicity to normal tissues while protecting against various forms of reactive oxygen species generation. Its capability to enhance the sensitivity of cancer cells to chemotherapy and radiotherapy has also been observed. This paper thoroughly reviews the current literature on nanoceria's applications within different cancer treatment modalities, with a specific focus on radiotherapy. The emphasis is on nanoceria's unique role in enhancing tumor radiosensitization and safeguarding normal tissues from radiation damage.

Engineered stem cell-based strategy: A new paradigm of next-generation stem cell product in regenerative medicine

Stem cells have garnered significant attention in regenerative medicine owing to their abilities of multi-directional differentiation and self-renewal. Despite these encouraging results, the market for stem cell products yields limited, which is largely due to the challenges faced to the safety and viability of stem cells in vivo. Besides, the fate of cells re-infusion into the body unknown is also a major obstacle to stem cell therapy. Actually, both the functional protection and the fate tracking of stem cells are essential in tissue homeostasis, repair, and regeneration. Recent studies have utilized cell engineering techniques to modify stem cells for enhancing their treatment efficiency or imparting them with novel biological capabilities, in which advances demonstrate the immense potential of engineered cell therapy. In this review, we proposed that the "engineered stem cells" are expected to represent the next generation of stem cell therapies and reviewed recent progress in this area. We also discussed potential applications of engineered stem cells and highlighted the most common challenges that must be addressed. Overall, this review has important guiding significance for the future design of new paradigms of stem cell products to improve their therapeutic efficacy.

Intranasal inorganic cerium oxide nanoparticles ameliorate oxidative stress induced motor manifestations in haloperidol-induced parkinsonism

Cerium oxide nanoparticles (CONPs), owing to their radical scavenging property, have recently emerged as a therapeutic candidate for oxidative stress-mediated neurological diseases. However, oral and intravenous administration of CONPs is limited due to their poor physicochemical characteristics, low bioavailability, rapid systemic clearance, poor blood-brain penetration and dose-dependent toxicity. To overcome these challenges, we developed intranasal CONPs and evaluated their potential in the experimental PD model. CONPs were prepared by homogenous precipitation using tween 80 as a stabilizer and methanol/water as solvent. The optimization was done using Central Composite Design (CCD). The CONPs synthesis was confirmed by UV and FTIR. The optimized CONPs were small-sized (105.1 ± 5.78 nm), spherical (TEM), uniform (PDI, 0.119 ± 0.006) and stable (ZP, -22.7 ± 1.02 mV). Energy-dispersive X-ray analysis showed characteristic signals of Ce in developed CONPs. The X-ray diffraction pattern described the cubic fluorite structure and nano-crystalline nature of CONPs. The CONP anti-oxidant activity was found to be 93.60 ± 0.32% at 25 µg/mL concentration. Finally, motor manifestation studies like the forced swim test, locomotor test, akinesia, catalepsy, and muscle coordination test were conducted to assess the motor dysfunctions and behavioral activity in all four animal groups. Results of the in vivo motor manifestation studies in the haloperidol-induced PD rat model showed that co-administration of intranasal CONPs along with a half dose of levodopa resulted in significant protection, and results were significantly different from the untreated group but not significantly different from the healthy group. In conclusion, intranasal CONPs can be useful in ameliorating oxidative stress through their antioxidant effect and could be prospective therapeutics for the treatment of motor manifestations in Parkinson's disease.

Cerium Oxide Nanoparticles Protect Cortical Astrocytes from Oxygen-Glucose Deprivation through Activation of the Ca2+ Signaling System

Most of the works aimed at studying the cytoprotective properties of nanocerium are usually focused on the mechanisms of regulation of the redox status in cells while the complex effects of nanocerium on calcium homeostasis, the expression of pro-apoptotic and protective proteins are generally overlooked. There is a problem of a strong dependence of the effects of cerium oxide nanoparticles on their size, method of preparation and origin, which significantly limits their use in medicine. In this study, using the methods of molecular biology, immunocytochemistry, fluorescence microscopy and inhibitory analysis, the cytoprotective effect of cerium oxide nanoparticles obtained by laser ablation on cultured astrocytes of the cerebral cortex under oxygen-glucose deprivation (OGD) and reoxygenation (ischemia-like conditions) are shown. The concentration effects of cerium oxide nanoparticles on ROS production by astrocytes in an acute experiment and the effects of cell pre-incubation with nanocerium on ROS production under OGD conditions were studied. The dose dependence for nanocerium protection of cortical astrocytes from a global increase in calcium ions during oxygen-glucose deprivation and cell death were demonstrated. The concentration range of cerium oxide nanoparticles at which they have a pro-oxidant effect on cells has been identified. The effect of nanocerium concentrations on astrocyte preconditioning, accompanied by increased expression of protective proteins and limited ROS production induced by oxygen-glucose deprivation, has been investigated. In particular, a correlation was found between an increase in the concentration of cytosolic calcium under the action of nanocerium and the suppression of cell death. As a result, the positive and negative effects of nanocerium under oxygen-glucose deprivation and reoxygenation in astrocytes were revealed at the molecular level. Nanocerium was found to act as a "double-edged sword" and to have a strictly defined concentration therapeutic "window".

Conservation of the enzyme-like activity and biocompatibility of CeO2 nanozymes in simulated body fluids

Cerium oxide nanozymes (CeO2NZs) are attracting vast attention due to their antioxidant and catalytic properties and mimic the activities of multiple endogenous enzymes. However, as is the case for nanomedicines in general, the success in showing their unique medical applications has not been matched by an understanding of their pharmacokinetics, which is delaying their implementation in clinical settings. Furthermore, the data of their modifications in body fluids and the impact on their activity are scarce. Herein, two types of widely used CeO2NZs, electrostatically stabilized and coated with a mesoporous silica shell, were exposed to simulated saliva and lung, gastric and intestinal fluids, and cell culture media. Their physicochemical modifications and bioactivity were tracked over time up to 15 days combining the data of different characterization techniques and biological assays. The results show that the biocompatibility and antioxidant activity are retained in all cases despite the different evolution behaviors in different fluids, including agglomeration. This work provides an experimental basis from a pharmacokinetic perspective that supports the therapeutic effectiveness of CeO2NZs observed in vivo for the treatment of many conditions related to chronic inflammation and cancer, and suggests that they can be safely administered through different portals of entry including intravenous injection, oral ingestion or inhalation.

A Ce-MOF@polydopamine composite nanozyme as an efficient scavenger for reactive oxygen species and iron in thalassemia disease therapy

Patients with β-thalassemia are prone to complications such as cardiovascular diseases and secretory gland injury due to iron overload (IO) and reactive oxygen species (ROS) production caused by blood transfusions. Simultaneously scavenging ROS and eliminating IO using nanomedicine remains challenging. Herein, we designed a dual-functional Ce-based metal-organic framework@polydopamine (Ce-MOF@PDA) composite that integrates oxidative stress reduction and IO elimination and evaluated its protective effect on IO injury in thalassemia. Using Ce-MOF with multiple active sites as the core, dopamine, which can coordinate iron ions, was modified on the surface of Ce-MOF and spontaneously polymerized to obtain PDA with iron elimination ability. Dopamine modification also adjusted the Ce3+/Ce4+ ratio to further enhance the catalytic activity for scavenging ROS. Ce-MOF@PDA exhibited multiple nanozyme activities, such as superoxide dismutase- and catalase-like activities, and decreased iron-mediated oxidative stress levels in vitro. Furthermore, the serum ferritin levels and iron concentrations in the liver of IO mice were reduced following treatment with Ce-MOF@PDA, and the fecal clearance ability was comparable to that of deferoxamine. These results indicate that Ce-MOF@PDA can eliminate IO while scavenging ROS and reduce tissue damage caused by oxidative stress. Therefore, the Ce-MOF@PDA nanozyme is a promising therapeutic nanomedicine for treating thalassemia IO.

Ce1-xZrxO2 nanoparticles in bacterial cellulose, bio-based composites with self-regenerating antioxidant capabilities

Bacterial cellulose (BC) is an emerging biopolymer with ever-widening uses in the biomedical field due to its purity, mechanical stability, conformability, moisture control, and biocompatibility. In the wet form, its highly porous nanofibrillar structure and abundant surface hydroxyl groups enable the functionalisation of BC with inorganic nanoparticles (NPs), granting the material additional purposive capabilities. As oxidative stress caused by reactive oxygen species (ROS) negatively affects various cellular structures, the functionalisation of BC with CeO2 NPs, known antioxidants, is pursued in this work to achieve composites capable of minimising inflammation and tissue damage. We report on low-temperature in situ syntheses of CeO2 NPs in BC enabling the formation of BC-CeO2 composites that exhibit self-regenerating antioxidant properties, as verified by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays and studies of the evolution in the CeO2 absorption edge (indicative of the Ce3+ and Ce4+ fractions). X-Ray photoelectron spectroscopy (XPS) further reveals that incorporation of zirconium into the CeO2 lattice leads to a four-fold increase in the Ce3+: Ce4+ ratio, thereby enhancing the composite antioxidant performance as exemplified by BC-Ce0.6Zr0.4O2 recording the highest %DPPH scavenging per unit mass of NPs among the BC-Ce1-xZrxO2 studied systems.

Antioxidant potential of nanomaterials

Background/aim

The novel field of nanomaterials allows infinite possibilities in order to create antioxidant therapies. The present review is aimed to describe the state of art concerning on nanomaterials and their effects on reactive oxygen species (ROS) production. A wide range of nanoparticles has been designed for this purpose, and each one possesses some particular characteristics which allow these significant antioxidant results. Several in vivo and in vitro works state the ability of these nanoparticles to mimic the redox systems of the cells, and thus, the potential role of nanoparticles as antioxidant treatment for several diseases.

Materials and methods

This paper was written after a review of the articles published on the field, using the "PubMed" and "Research Gate" databases.

Results

The main types of nanoparticles are listed and explained below, offering a global vision of the field with great interest for research. Antitumor chemo- and radiotherapies have been found to improve efficacy by enhancing the selectivity of cytocidal effects and minimizing systemic adverse effects when such materials are used. Furthermore, catalytic nanomaterials can execute energy-free antioxidant cycles that scavenge the most harmful reactive oxygen species via SOD- and catalase-like activities.

Conclusion

This unique method is projected to result in significant gains in the long run. However, due to a lack of understanding of potential adverse body reactions to these novel strategies, caution must be exercised. Analyzing the biocompatibility of these nanomaterials carefully, particularly in terms of biokinetics and the problems that could arise from long-term retention of nonbiodegradable inorganic nanomaterials, is required.

Rising Influence of Nanotechnology in Addressing Oxidative Stress-Related Liver Disorders

Reactive oxygen species (ROS) play a significant role in the survival and decline of various biological systems. In liver-related metabolic disorders such as steatohepatitis, ROS can act as both a cause and a consequence. Alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH) are two distinct types of steatohepatitis. Recently, there has been growing interest in using medications that target ROS formation and reduce ROS levels as a therapeutic approach for oxidative stress-related liver disorders. Mammalian systems have developed various antioxidant defenses to protect against excessive ROS generation. These defenses modulate ROS through a series of reactions, limiting their potential impact. However, as the condition worsens, exogenous antioxidants become necessary to control ROS levels. Nanotechnology has emerged as a promising avenue, utilizing nanocomplex systems as efficient nano-antioxidants. These systems demonstrate enhanced delivery of antioxidants to the target site, minimizing leakage and improving targeting accuracy. Therefore, it is essential to explore the evolving field of nanotechnology as an effective means to lower ROS levels and establish efficient therapeutic interventions for oxidative stress-related liver disorders.

Rising Influence of Nanotechnology in Addressing Oxidative Stress-Related Liver Disorders

Reactive oxygen species (ROS) play a significant role in the survival and decline of various biological systems. In liver-related metabolic disorders such as steatohepatitis, ROS can act as both a cause and a consequence. Alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH) are two distinct types of steatohepatitis. Recently, there has been growing interest in using medications that target ROS formation and reduce ROS levels as a therapeutic approach for oxidative stress-related liver disorders. Mammalian systems have developed various antioxidant defenses to protect against excessive ROS generation. These defenses modulate ROS through a series of reactions, limiting their potential impact. However, as the condition worsens, exogenous antioxidants become necessary to control ROS levels. Nanotechnology has emerged as a promising avenue, utilizing nanocomplex systems as efficient nano-antioxidants. These systems demonstrate enhanced delivery of antioxidants to the target site, minimizing leakage and improving targeting accuracy. Therefore, it is essential to explore the evolving field of nanotechnology as an effective means to lower ROS levels and establish efficient therapeutic interventions for oxidative stress-related liver disorders.

Synthesis of Stable Cerium Oxide Nanoparticles Coated with Phosphonic Acid-Based Functional Polymers

Functional polymers, such as poly(ethylene glycol) (PEG), terminated with a single phosphonic acid, hereafter PEG_ik-Ph are often applied to coat metal oxide surfaces during post-synthesis steps but are not sufficient to stabilize sub-10 nm particles in protein-rich biofluids. The instability is attributed to the weak binding affinity of post-grafted phosphonic acid groups, resulting in a gradual detachment of the polymers from the surface. Here, we assess these polymers as coating agents using an alternative route, namely, the one-step wet-chemical synthesis, where PEG_ik-Ph is introduced with cerium precursors during the synthesis. Characterization of the coated cerium oxide nanoparticles (CNPs) indicates a core-shell structure, where the cores are 3 nm cerium oxide and the shell consists of functionalized PEG polymers in a brush configuration. Results show that CNPs coated with PEG_1k-Ph and PEG_2k-Ph are of potential interest for applications as nanomedicines due to their high Ce(III) content and increased colloidal stability in cell culture media. We further demonstrate that the CNPs in the presence of hydrogen peroxide show an additional absorbance band in the UV-vis spectrum, which is attributed to Ce-O₂^2- peroxo-complexes and could be used in the evaluation of their catalytic activity for scavenging reactive oxygen species.

Recent Advances in Nanomedicine Development for Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the major causes of morbidity and mortality worldwide, and it is also a risk factor for neurodegeneration. However, there has not been perceptible progress in treating acute TBI over the last few years, mainly due to the inability of therapeutic drugs to cross the blood-brain barrier (BBB), failing to exert significant pharmacological effects on the brain parenchyma. Recently, nanomedicines are emerging as a powerful tool for the treatment of TBI where nanoscale materials (also called nanomaterials) are employed to deliver therapeutic agents. The advantages of using nanomaterials as a drug carrier include their high solubility and stability, high carrier capacity, site-specific, improved pharmacokinetics, and biodistribution. Keeping these points in consideration, this article reviews the pathophysiology, current treatment options, and emerging nanomedicine strategies for the treatment of TBI. The review will help readers to gain insight into the state-of-the-art of nanomedicine as a new tool for the treatment of TBI.

Self-assembled three-dimensional hydrogels based on graphene derivatives and cerium oxide nanoparticles: scaffolds for co-culture of oligodendrocytes and neurons derived from neural stem cells

Stem cell-based therapies have shown promising results for the regeneration of the nervous system. However, the survival and integration of the stem cells in the neural circuitry is suboptimal and might compromise the therapeutic outcomes of this approach. The development of functional scaffolds capable of actively interacting with stem cells may overcome the current limitations of stem cell-based therapies. In this study, three-dimensional hydrogels based on graphene derivatives and cerium oxide (CeO₂) nanoparticles are presented as prospective supports allowing neural stem cell adhesion, migration and differentiation. The morphological, mechanical and electrical properties of the resulting hydrogels can be finely tuned by controlling several parameters of the self-assembly of graphene oxide sheets, namely the amount of incorporated reducing agent (ascorbic acid) and CeO₂ nanoparticles. The intrinsic properties of the hydrogels, as well as the presence of CeO₂ nanoparticles, clearly influence the cell fate. Thus, stiffer adhesion substrates promote differentiation to glial cell lineages, while softer substrates enhance mature neuronal differentiation. Remarkably, CeO₂ nanoparticle-containing hydrogels support the differentiation of neural stem cells to neuronal, astroglial and oligodendroglial lineage cells, promoting the in vitro generation of nerve tissue grafts that might be employed in neuroregenerative cell therapies.

The interaction mechanisms of co-existing polybrominated diphenyl ethers and engineered nanoparticles in environmental waters: A critical review

This review focuses on the occurrence and interactions of engineered nanoparticles (ENPs) and brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) in water systems and the generation of highly complex compounds in the environment. The release of ENPs and BFRs (e.g. PBDEs) to aquatic environments during their usage and disposal are summarised together with their key interaction mechanisms. The major interaction mechanisms including electrostatic, van der Waals, hydrophobic, molecular bridging and steric, hydrogen and π-bonding, cation bridging and ligand exchange were identified. The presence of ENPs could influence the fate and behaviour of PBDEs through the interactions as well as induced reactions under certain conditions which increases the formation of complex compounds. The interaction leads to alteration of behaviour for PBDEs and their toxic effects to ecological receptors. The intermingled compound (ENPs-BFRs) would show different behaviour from the parental ENPs or BFRs, which are currently lack of investigation. This review provided insights on the interactions of ENPs and BFRs in artificial, environmental water systems and wastewater treatment plants (WWTPs), which are important for a comprehensive risk assessment.

Insights from a Bibliometrics-Based Analysis of Publishing and Research Trends on Cerium Oxide from 1990 to 2020

The purpose of this study is to evaluate the literature for research trends on cerium oxide from 1990 to 2020 and identify gaps in knowledge in the emerging application(s) of CeONP. Bibliometric methods were used to identify themes in database searches from PubMed, Scopus and Web of Science Core Collection using SWIFT-Review, VOSviewer and SciMAT software programs. A systematic review was completed on published cerium oxide literature extracted from the Scopus database (n = 17,115), identifying themes relevant to its industrial, environmental and biomedical applications. A total of 172 publications were included in the systematic analysis and categorized into four time periods with research themes identified; "doping additives" (n = 5, 1990-1997), "catalysts" (n = 32, 1998-2005), "reactive oxygen species" (n = 66, 2006-2013) and "pathology" (n = 69, 2014-2020). China and the USA showed the highest number of citations and publications for cerium oxide research from 1990 to 2020. Longitudinal analysis showed CeONP has been extensively used for various applications due to its catalytic properties. In conclusion, this study showed the trend in research in CeONP over the past three decades with advancements in nanoparticle engineering like doping, and more recently surface modification or functionalization to further enhanced its antioxidant abilities. As a result of recent nanoparticle engineering developments, research into CeONP biological effects have highlighted its therapeutic potential for a range of human pathologies such as Alzheimer's disease. Whilst research over the past three decades show the versatility of cerium oxide in industrial and environmental applications, there are still research opportunities to investigate the potential beneficial effects of CeONP in its application(s) on human health.

Repeated Topical Administration of 3 nm Cerium Oxide Nanoparticles Reverts Disease Atrophic Phenotype and Arrests Neovascular Degeneration in AMD Mouse Models

Increased oxidative stress in the retina and retinal pigment epithelium is implicated in age-related macular degeneration (AMD). Antioxidant cerium oxide nanoparticles (CeO2NPs) have been used to treat degenerative retinal pathologies in animal models, although their delivery route is not ideal for chronic patient treatment. In this work, we prepared a formulation for ocular topical delivery that contains small (3 nm), nonaggregated biocompatible CeO2NPs. In vitro results indicate the biocompatible and protective character of the CeO2NPs, reducing oxidative stress in ARPE19 cells and inhibiting neovascularization related to pathological angiogenesis in both HUVEC and in in vitro models of neovascular growth. In the in vivo experiments, we observed the capacity of CeO2NPs to reach the retina after topical delivery and a subsequent reversion of the altered retinal transcriptome of the retinal degenerative mouse model DKOrd8 toward that of healthy control mice, together with signs of decreased inflammation and arrest of degeneration. Furthermore, CeO2NP eye drops' treatment reduced laser-induced choroidal neovascular lesions in mice by lowering VEGF and increasing PEDF levels. These results indicate that CeO2NP eye drops are a beneficial antioxidant and neuroprotective treatment for both dry and wet forms of AMD disease.

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.

Therapeutic potential of nanoceria pretreatment in preventing the development of urological chronic pelvic pain syndrome: Immunomodulation via reactive oxygen species scavenging and SerpinB2 downregulation

Urological chronic pelvic pain syndrome (UCPPS) manifests as pelvic pain with frequent urination and has a 10% prevalence rate without effective therapy. Nanoceria (cerium oxide nanoparticles [CNPs]) were synthesized in this study to achieve potential long-term pain relief, using a commonly used UCPPS mouse model with cyclophosphamide-induced cystitis. Transcriptome sequencing analysis revealed that serpin family B member 2 (SerpinB2) was the most upregulated marker in mouse bladder, and SerpinB2 was downregulated with CNP pretreatment. The transcriptome sequencing analysis results agreed with quantitative polymerase chain reaction and western blot analysis results for the expression of related mRNAs and proteins. Analysis of Gene Expression Omnibus (GEO) datasets revealed that SerpinB2 was a differentially upregulated gene in human UCPPS. In vitro SerpinB2 knockdown downregulated proinflammatory chemokine expression (chemokine receptor CXCR3 and C-X-C motif chemokine ligand 10) upon treatment with 4-hydroperoxycyclophosphamide. In conclusion, CNP pretreatment may prevent the development of UCPPS, and reactive oxygen species (ROS) scavenging and SerpinB2 downregulation may modulate the immune response in UCPPS.

Recent advances in nanomaterials for the treatment of spinal cord injury

Spinal cord injuries (SCIs) are devastating. In SCIs, a powerful traumatic force impacting the spinal cord results in the permanent loss of nerve function below the injury level, leaving the patient paralyzed and wheelchair-bound for the remainder of his/her life. Unfortunately, clinical treatment that depends on surgical decompression appears to be unable to handle damaged nerves, and high-dose methylprednisolone-based therapy is also associated with problems, such as infection, gastrointestinal bleeding, femoral head necrosis, obesity, and hyperglycemia. Nanomaterials have opened new avenues for SCI treatment. Among them, performance-based nanomaterials derived from a variety of materials facilitate improvements in the microenvironment of traumatic injury and, in some cases, promote neuron regeneration. Nanoparticulate drug delivery systems enable the optimization of drug effects and drug bioavailability, thus contributing to the development of novel treatments. The improved efficiency and accuracy of gene delivery will also benefit the exploration of SCI mechanisms and the understanding of key genes and signaling pathways. Herein, we reviewed different types of nanomaterials applied to the treatment of SCI and summarized their functions and advantages to provide new perspectives for future clinical therapies.

Reversing the immunosuppressive microenvironment with reduced redox level by microwave-chemo-immunostimulant Ce-Mn MOF for improved immunotherapy

BACKGROUNDS

Reversing the immunosuppressive tumor microenvironment (TME) in the tumor is widely deemed to be an effective strategy to improve immune therapy. In particular, the redox balance in TME needs to be well controlled due to its critical role in mediating the functions of various cells, including cancer cells and immune-suppressive cells.

RESULTS

Here, we propose an efficient strategy to reshape the redox homeostasis to reverse immunosuppressive TME. Specifically, we developed a microwave-chemo-immunostimulant CMMCP to promote the infiltration of the tumor-T cells by simultaneously reducing the reactive oxygen species (ROS) and glutathione (GSH) and improving the oxygen (O₂) levels in TME. The CMMCP was designed by loading chemotherapy drugs cisplatin into the bimetallic Ce-Mn MOF nanoparticles coated with polydopamine. The Ce-Mn MOF nanoparticles can effectively improve the catalytic decomposition of ROS into O₂ under microwave irradiation, resulting in overcoming hypoxia and limited ROS generation. Besides, the activity of intracellular GSH in TME was reduced by the redox reaction with Ce-Mn MOF nanoparticles. The reprogrammed TME not only boosts the immunogenic cell death (ICD) induced by cisplatin and microwave hyperthermia but also gives rise to the polarization of pro-tumor M2-type macrophages to the anti-tumor M1-type ones.

CONCLUSION

Our in vivo experimental results demonstrate that the microwave-chemo-immunostimulant CMMCP significantly enhances the T cell infiltration and thus improves the antitumor effect. This study presents an easy, safe, and effective strategy for a whole-body antitumor effect after local treatment.

Characterization and antimicrobial activity of cerium oxide nanoparticles synthesized using neem and ginger

The aim of this study is to analyze and characterize the antimicrobial effect of cerium oxide nanoparticles (NP) synthesized using neem and ginger. Finely grounded neem and ginger powder were taken and mixed with distilled water. This mixture was then heated and filtered. Ammonium cerium nitrate dissolved in distilled water. Both the mixtures were mixed and stirred magnetically. A double-beam ultraviolet-visible spectrophotometer was used to monitor color changes. The extract was centrifuged at 8000 rpm for 15 min. The final pellet was powdered using a hot air oven at 70°C for 24 h. Visualization was done by transmission electron microscopy and spherical morphology was noted, with an average diameter of 5 nm, in aggregated form. The sample containing 100 mg of cerium oxide shows the most significant effect on the zone of inhibition of 11 mm of Staphylococcus aureus. The results obtained in the current study confirmed that CeO-NP possessed antioxidant and cytotoxic properties.

A study of the comparative effect of cerium oxide and cerium peroxide on stimulation of angiogenesis: Design and synthesis of pro-angiogenic chitosan/collagen hydrogels

Poor angiogenesis at injury site is a major problem in chronic wounds, which could lead to limbs amputation in adverse cases. To overcome this issue, several efforts have made in literature and by our group as well to develop pro-angiogenic agents. For this purpose, metal oxides due to their oxidative potential have been studied and found very attractive agents. Cerium oxides are proven to be non-toxic and their biological studies have already proved their importance in preventing chronic inflammation, and neurological diseases among several others by modulating the intracellular reactive oxygen species. In current study, we report the synthesis and neovascularization activity of cerium oxide and cerium peroxide nanoparticles when loaded into chitosan and collagen hydrogel. The hydrogels were characterized by FTIR, SEM and XRD. The pro-angiogenic behavior of these hydrogels was studied by in-vivo CAM assay. It was found that cerium peroxide loaded material showed significantly increase in angiogenesis as compared to cerium oxide loaded materials. It was demonstrated that cerium peroxide hydrogels enhanced the angiogenic capability in CAM assay as compared to cerium oxide and hence holds good potential for chronic ulcer and burn wounds healing.

Preparation of zinc oxide nanoparticles using laser-ablation technique: Retinal epithelial cell (ARPE-19) biocompatibility and antimicrobial activity when activated with femtosecond laser

The unusual physical, chemical, and biological features of nanoparticles have sparked considerable attention in the ophthalmological applications. This study reports the synthesis and characterization of zinc oxide nanoparticles (ZnONPs) using laser-ablation at 100 mJ with different ablation times. The synthesized ZnONPs were spherical with an average size of 10.2 nm or 9.8 nm for laser ablation times of 20 and 30 min, respectively. The ZnONPs were screened for their antimicrobial activity against ophthalmological bacteria, methicillin-resistant S. aureus (MRSA) and Pseudomonas aeruginosa. The significant decrease in bacterial growth was observed after treatment with ZnONPs in combination with 400 nm femtosecond laser irradiation. ZnONPs were investigated for their antioxidant activity and biocompatibility towards retinal epithelial cells (ARPE-19). ZnONPs showed moderate antioxidant and free radical scavenging activity. ZnONPs prepared with an ablation time of 20 min were safer and more biocompatible than those prepared with an ablation time of 30 min, which were toxic to ARPE-19 cells with LC₅₀ (11.3 μg/mL) and LC₉₀ (18.3 μg/mL). In this study, laser ablation technique was used to create ZnONPs, and it was proposed that ZnONPs could have laser-activated antimicrobial activity for ophthalmological applications.

Enhanced Antioxidant Ability of PEG-Coated Ce0.5Zr0.5O2-Based Nanofluids for Scavenging Hydroxyl Radicals

The antioxidant therapy to preserve residual hearing is relatively recent, and the search for effective antioxidants is still ongoing. Though nanoceria has shown promising radical-scavenging capability, improving its antioxidant ability and the dispersion stability of its nanofluid, which is critical to the desired site, i.e., cochlea, still remains a major challenge. The objective of the present work is to study the radical-scavenging capability of poly(ethylene glycol) (PEG)-coated CeO₂ and Ce_0.5Zr_0.5O₂ nanoparticles in water and the biologically relevant fluid (PBS buffer). Nanoparticles in the size range of 4.0-9.0 nm are synthesized using the coprecipitation method and characterized using suitable techniques. The scavenging and dispersion stability of the synthesized nanofluid are analyzed using a UV-vis spectrophotometer. It is found that the addition of PEG during the synthesis process promoted the generation of finer nanoparticles with a narrow size distribution and the doping of zirconium produced a large number of defects in the crystallite structure. The PEG coating over the nanoparticles improved the dispersion stability of nanofluids without affecting their surface reactivity, and it is found to be 94 and 80% in water and PBS, respectively, at 500 μM and 60 min, which is maintained till 90 min. The highest scavenging of hydroxyl radicals by PEG-coated Ce_0.5Zr_0.5O₂ is found to be 60%, which is significantly superior to that of CeO₂. The scavenging capability is found to be increased with the concentration of nanoparticles, showing the best scavenging activity at 190 and 150 μM for PEG-coated CeO₂ and Ce_0.5Zr_0.5O₂, respectively, and the scavenging in water is at par with that of PBS, indicating that these nanoparticles are suitable to be used in sites where a biologically relevant fluid is present, e.g., the cochlea. It is proposed that PEG-coated Ce_0.5Zr_0.5O₂ having an average size of ∼ 4 nm can be a potential antioxidant in relevant biomedical applications.

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.

Improving the valence self-reversible conversion of cerium nanoparticles on titanium implants by lanthanum doping to enhance ROS elimination and osteogenesis

Equipped with anti-oxidative properties, cerium oxide nanoparticles (CNPs) are gradually being adopted over the years in the field of oxidative stress research. However, the effects of CNPs may be diminished when under the influence of prolonged and substantially elevated levels of oxidative stress. Therefore, it is imperative to enhance the efficacy of CNPs to resist oxidative stress. In this study, our approach involves the fabrication of titanium surface CNPs coatings doped with different concentrations of lanthanum ions (La³⁺) and the investigation of their local anti-oxidative stress potential. The physicochemical characterization showed that the La-CNPs groups had a substantial increase in the generation of oxygen vacancies within the CNPs structure with the increase of La doping concentration. In vitro findings proofed that the cytocompatibility of different La-CNPs coatings showed a trend of increasing first and then decreasing with the increase of La doping concentration under oxidative stress microenvironment. Among these groups, the 30 % La-CNPs group presented the best cell proliferation and osteogenic differentiation which could activate the FoxO1 pathway, then upregulated the expression of SOD1 and CAT, and finally resulted in the inhibition of ROS production. In vivo results further confirmed that the 30 % La-CNPs group showed significant osteogenic effects in two rat models (osteoporosis and diabetes models). In conclusion, we believe that the 30 % La-CNPs coating holds promising potential for its implant applications in patients with oxidative stress-related diseases.

Central nervous system injury meets nanoceria: opportunities and challenges

Central nervous system (CNS) injury, induced by ischemic/hemorrhagic or traumatic damage, is one of the most common causes of death and long-term disability worldwide. Reactive oxygen and nitrogen species (RONS) resulting in oxidative/nitrosative stress play a critical role in the pathological cascade of molecular events after CNS injury. Therefore, by targeting RONS, antioxidant therapies have been intensively explored in previous studies. However, traditional antioxidants have achieved limited success thus far, and the development of new antioxidants to achieve highly effective RONS modulation in CNS injury still remains a great challenge. With the rapid development of nanotechnology, novel nanomaterials provided promising opportunities to address this challenge. Within these, nanoceria has gained much attention due to its regenerative and excellent RONS elimination capability. To promote its practical application, it is important to know what has been done and what has yet to be done. This review aims to present the opportunities and challenges of nanoceria in treating CNS injury. The physicochemical properties of nanoceria and its interaction with RONS are described. The applications of nanoceria for stroke and neurotrauma treatment are summarized. The possible directions for future application of nanoceria in CNS injury treatment are proposed.

Advances of nano drug delivery system for the theranostics of ischemic stroke

From the global perspective, stroke refers to a highly common cause of disability and death. Ischemic stroke (IS), attributed to blood vessel blockage, preventing the flow of blood to brain, acts as the most common form of stroke. Thus far, thrombolytic therapy is the only clinical treatment for IS with the approval from the FDA. Moreover, the physiology barrier complicates therapeutically and diagnostically related intervention development of IS. Accordingly, developing efficient and powerful curative approaches for IS diagnosis and treatment is urgently required. The advent of nanotechnology has brought dawn and hope to better curative and imaging forms for the management of IS. This work reviews the recent advances and challenges correlated with the nano drug delivery system for IS therapy and diagnosis. The overview of the current knowledge of the important molecular pathological mechanisms in cerebral ischemia and how the drugs cross the blood brain barrier will also be briefly summarized.