Custom cerium oxide nanoparticles protect against a free radical mediated autoimmune degenerative disease in the brain

Yttrium oxide nanoparticles alleviate cognitive deficits, neuroinflammation, and mitochondrial biogenesis impairment induced by streptozotocin

Alzheimer's disease (AD) is a common neurodegenerative disorder characterized by progressive cognitive decline. Yttrium oxide nanoparticles (Y2O3NPs) have recently attracted much attention for their potential anti-inflammatory and antioxidant properties. However, the effects of Y2O3NPs in animal models of AD are less studied. This study aimed to investigate the potential therapeutic effects of Y2O3NPs in streptozotocin (STZ)-treated rats, a reliable animal model of AD, with special emphasis on cognitive function, neuroinflammation, and mitochondrial biogenesis in the hippocampus. Male Wistar rats were stereotaxically injected with STZ (3 mg/kg, 3 µl/ventricle). Three weeks after STZ injection, cognitive function was assessed using the Morris water maze, elevated plus maze, and passive avoidance tasks. Intraperitoneal treatment with Y2O3NPs (0.1, 0.3, or 0.5 mg/kg) was started 24 h after the STZ injection and continued for 21 days. The mRNA and protein levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and components involved in mitochondrial biogenesis (PGC-1α, NRF-1, and TFAM) were measured in the hippocampus. The results indicated that STZ induced cognitive impairment and led to neuroinflammation and mitochondrial biogenesis impairment in the hippocampus of rats. Interestingly, treatment with Y2O3NPs effectively reduced STZ-induced cognitive deficits in a dose-dependent manner, possibly by attenuating neuroinflammation and mitochondrial biogenesis impairment. These findings suggest that Y2O3NPs can be considered as a promising therapeutic agent for treating or ameliorating the neuropathological effects associated with AD.

Bibliometric and visualization analysis of the application of inorganic nanomaterials to autoimmune diseases

Objective: To conduct bibliometric analysis of the application of inorganic nanomaterials to autoimmune diseases to characterize current research trends and to visualize past and emerging trends in this field in the past 15 years. Methods: The evolution and thematic trends of the application of inorganic nanomaterials to autoimmune diseases from January 1, 1985, to March 15, 2024, were analyzed by bibliometric analysis of data retrieved and extracted from the Web of Science Core Collection (WoSCC) database. A total of 734 relevant reports in the literature were evaluated according to specific characteristics such as year of publication, journal, institution, country/region, references, and keywords. VOSviewer was used to build co-authorship analysis, co-occurrence analysis, co-citation analysis, and network visualization. Some important subtopics identified by bibliometric characterization are further discussed and reviewed. Result: From 2009 to 2024, annual publications worldwide increased from 11 to 95, an increase of 764%. ACS Nano published the most papers (14) with the most citations (1372). China (230 papers, 4922 citations) and the Chinese Academy of Sciences (36 papers, 718 citations) are the most productive and influential country and institution, respectively. The first 100 keywords were co-clustered to form four clusters: (1) the application of inorganic nanomaterials in drug delivery, (2) the application of inorganic nano-biosensing to autoimmune diseases, (3) the use of inorganic nanomaterials for imaging applied to autoimmune diseases, and (4) the application of inorganic nanomaterials in the treatment of autoimmune diseases. Combination therapy, microvesicles, photothermal therapy (PTT), targeting, diagnostics, transdermal, microneedling, silver nanoparticles, psoriasis, and inflammatory cytokines are the latest high-frequency keywords, marking the emerging frontier of inorganic nanomaterials in the field of autoimmune diseases. Sub-topics were further discussed to help researchers determine the scope of research topics and plan research directions. Conclusion: Over the past 39 years, the application of inorganic nanotechnology to the field of autoimmune diseases shows extensive cooperation between countries and institutions, showing a continuous increase in the number of reports in the literature, and has clinical translation prospects. Future research should further improve the safety of inorganic nanomaterials, clarify the mechanism of action of nanomaterials, establish a standardized nanomaterial preparation and performance evaluation system, and ultimately achieve the goal of early detection and precise treatment of autoimmune diseases.

The effect of intra spinal administration of cerium oxide nanoparticles on central pain mechanism: An experimental study

This study investigated Cerium oxide nanoparticles (CeONPs) effect on central neuropathic pain (CNP). The compressive method of spinal cord injury (SCI) model was used for pain induction. Three groups were formed by a random allocation of 24 rats. In the treatment group, CeONPs were injected above and below the lesion site immediately after inducing SCI. pain symptoms were evaluated using acetone, Radian Heat, and Von Frey tests weekly for six weeks. Finally, we counted fibroblasts using H&E staining. We evaluated the expression of Cx43, GAD65 and HDAC2 proteins using the western blot method. The analysis of results was done by PRISM software. At the end of the study, we found that CeONPs reduced pain symptoms to levels similar to those observed in normal animals. CeONPs also increased the expression of GAD65 and Cx43 proteins but did not affect HDAC2 inhibition. CeONPs probably have a pain-relieving effect on chronic pain by potentially preserving GAD65 and Cx43 protein expression and hindering fibroblast infiltration.

Targeting Macrophage Polarization for Reinstating Homeostasis following Tissue Damage

Tissue regeneration and remodeling involve many complex stages. Macrophages are critical in maintaining micro-environmental homeostasis by regulating inflammation and orchestrating wound healing. They display high plasticity in response to various stimuli, showing a spectrum of functional phenotypes that vary from M1 (pro-inflammatory) to M2 (anti-inflammatory) macrophages. While transient inflammation is an essential trigger for tissue healing following an injury, sustained inflammation (e.g., in foreign body response to implants, diabetes or inflammatory diseases) can hinder tissue healing and cause tissue damage. Modulating macrophage polarization has emerged as an effective strategy for enhancing immune-mediated tissue regeneration and promoting better integration of implantable materials in the host. This article provides an overview of macrophages' functional properties followed by discussing different strategies for modulating macrophage polarization. Advances in the use of synthetic and natural biomaterials to fabricate immune-modulatory materials are highlighted. This reveals that the development and clinical application of more effective immunomodulatory systems targeting macrophage polarization under pathological conditions will be driven by a detailed understanding of the factors that regulate macrophage polarization and biological function in order to optimize existing methods and generate novel strategies to control cell phenotype.

Nanoparticle-neutrophils interactions for autoimmune regulation

Neutrophils play an essential role as 'first responders' in the immune response, necessitating many immune-modulating capabilities. Chronic, unresolved inflammation is heavily implicated in the progression and tissue-degrading effects of autoimmune disease. Neutrophils modulate disease pathogenesis by interacting with the inflammatory and autoreactive cells through effector functions, including signaling, degranulation, and neutrophil extracellular traps (NETs) release. Since the current gold standard systemic glucocorticoid administration has many drawbacks and side effects, targeting neutrophils in autoimmunity provides a new approach to developing therapeutics. Nanoparticles enable targeting of specific cell types and controlled release of a loaded drug cargo. Thus, leveraging nanoparticle properties and interactions with neutrophils provides an exciting new direction toward novel therapies for autoimmune diseases. Additionally, recent work has utilized neutrophil properties to design novel targeted particles for delivery into previously inaccessible areas. Here, we outline nanoparticle-based strategies to modulate neutrophil activity in autoimmunity, including various nanoparticle formulations and neutrophil-derived targeting.

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.

Ceria-Based Therapeutic Antioxidants for Biomedical Applications

The growing interest in nanomedicine over the last 20 years has carved out a research field called "nanocatalytic therapy," where catalytic reactions mediated by nanomaterials are employed to intervene in disease-critical biomolecular processes. Among many kinds of catalytic/enzyme-mimetic nanomaterials investigated thus far, ceria nanoparticles stand out from others owing to their unique scavenging properties against biologically noxious free radicals, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), by exerting enzyme mimicry and nonenzymatic activities. Much effort has been made to utilize ceria nanoparticles as self-regenerating antioxidative and anti-inflammatory agents for various kinds of diseases, given the detrimental effects of ROS and RNS therein that need alleviation. In this context, this review is intended to provide an overview as to what makes ceria nanoparticles merit attention in disease therapy. The introductory part describes the characteristics of ceria nanoparticles as an oxygen-deficient metal oxide. The pathophysiological roles of ROS and RNS are then presented, as well as their scavenging mechanisms by ceria nanoparticles. Representative examples of recent ceria-nanoparticle-based therapeutics are summarized by categorization into organ and disease types, followed by the discussion on the remaining challenges and future research directions.

Modulation of proteins by rare earth elements as a biotechnological tool

Although rare earth element (REE) complexes are often utilized in bioimaging due to their photo- and redox stability, magnetic and optical characteristics, they are also applied for pharmaceutical applications due to their interaction with macromolecules namely proteins. The possible implications induced by REEs through modification in the function or regulatory activity of the proteins trigger a variety of applications for these elements in biomedicine and biotechnology. Lanthanide complexes have particularly been applied as anti-biofilm agents, cancer inhibitors, potential inflammation inhibitors, metabolic elicitors, and helper agents in the cultivation of unculturable strains, drug delivery, tissue engineering, photodynamic, and radiation therapy. This paper overviews emerging applications of REEs in biotechnology, especially in biomedical imaging, tumor diagnosis, and treatment along with their potential toxic effects. Although significant advances in applying REEs have been made, there is a lack of comprehensive studies to identify the potential of all REEs in biotechnology since only four elements, Eu, Ce, Gd, and La, among 17 REEs have been mostly investigated. However, in depth research on ecotoxicology, environmental behavior, and biological functions of REEs in the health and disease status of living organisms is required to fill the vital gaps in our understanding of REEs applications.

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

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

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

BACKGROUND

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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

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

Neuroprotective effects of polyacrylic acid (PAA) conjugated cerium oxide against hydrogen peroxide- and 6-OHDA-induced SH-SY5Y cell damage

Cerium oxide nanoparticles have been widely investigated against neurodegenerative diseases due to their antioxidant properties that aid in quenching reactive oxygen species. In this study, polyacrylic acid conjugated cerium oxide (PAA-CeO) nanoparticles were synthesized in a 50-60 nm size range with a zeta potential of - 35 mV. X-ray photoelectron spectroscopy analysis revealed a mixed valence state of Ce4+ and Ce3+. PAA-CeO nanoparticles were safe for undifferentiated (UN-) and retinoic acid-differentiated (RA-) human neuroblastoma SH-SY5Y cells and reduced the extent of cell damage evoked by hydrogen peroxide (H2O2) and 6-hydroxydopamine (6-OHDA). In the H2O2 model of cell damage PAA-CeO did not affect the caspase-3 activity (apoptosis marker) but attenuated the number of propidium iodide-positive cells (necrosis marker). In the 6-OHDA model, nanoparticles profoundly reduced necrotic changes and partially attenuated caspase-3 activity. However, we did not observe any impact of PAA-CeO on intracellular ROS formation induced by H2O2. Further, the flow cytometry analysis of fluorescein isothiocyanate-labeled PAA-CeO revealed a time- and concentration-dependent cellular uptake of nanoparticles. The results point to the neuroprotective potential of PAA-CeO nanoparticles against neuronal cell damage induced by H2O2 and 6-OHDA, which are in both models associated with the inhibition of necrotic processes and the model-dependent attenuation of activity of executor apoptotic protease, caspase-3 (6-OHDA model) but not with the direct inhibition of ROS (H2O2 model).

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".

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

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

Molecular Imaging Investigations of Polymer-Coated Cerium Oxide Nanoparticles as a Radioprotective Therapeutic Candidate

Cerium oxide nanoparticles (CONPs) have a unique surface redox chemistry that appears to selectively protect normal tissues from radiation induced damage. Our prior research exploring the biocompatibility of polymer-coated CONPs found further study of poly-acrylic acid (PAA)-coated CONPs was warranted due to improved systemic biodistribution and rapid renal clearance. This work further explores PAA-CONPs' radioprotective efficacy and mechanism of action related to tumor microenvironment pH. An ex vivo TUNEL assay was used to measure PAA-CONPs' protection of the irradiated mouse colon in comparison to the established radioprotector amifostine. [18F]FDG PET imaging of spontaneous colon tumors was utilized to determine the effects of PAA-CONPs on tumor radiation response. In vivo MRI and an ex vivo clonogenic assay were used to determine pH effects on PAA-CONPs' radioprotection in irradiated tumor-bearing mice. PAA-CONPs showed excellent radioprotective efficacy in the normal colon that was equivalent to uncoated CONPs and amifostine. [18F]FDG PET imaging showed PAA-CONPs do not affect tumor response to radiation. Normalization of tumor pH allowed some radioprotection of tumors by PAA-CONPs, which may explain their lack of tumor radioprotection in the acidic tumor microenvironment. Overall, PAA-CONPs meet the criteria for clinical application as a radioprotective therapeutic agent and are an excellent candidate for further study.

Antioxidant and Prooxidant Nanozymes: From Cellular Redox Regulation to Next-Generation Therapeutics

Nanozymes, nanomaterials with enzyme-mimicking activity, have attracted tremendous interest in recent years owing to their ability to replace natural enzymes in various biomedical applications, such as biosensing, therapeutics, drug delivery, and bioimaging. In particular, the nanozymes capable of regulating the cellular redox status by mimicking the antioxidant enzymes in mammalian cells are of great therapeutic significance in oxidative-stress-mediated disorders. As the distinction of physiological oxidative stress (oxidative eustress) and pathological oxidative stress (oxidative distress) occurs at a fine borderline, it is a great challenge to design nanozymes that can differentially sense the two extremes in cells, tissues and organs and mediate appropriate redox chemical reactions. In this Review, we summarize the advances in the development of redox-active nanozymes and their biomedical applications. We primarily highlight the therapeutic significance of the antioxidant and prooxidant nanozymes in various disease model systems, such as cancer, neurodegeneration, and cardiovascular diseases. The future perspectives of this emerging area of research and the challenges associated with the biomedical applications of nanozymes are described.

Carboxylic acids and light interact to affect nanoceria stability and dissolution in acidic aqueous environments

Cerium atoms on the surfaces of nanoceria (i.e., cerium oxide in the form of nanoparticles) can store or release oxygen, cycling between Ce3+ and Ce4+; therefore, they can cause or relieve oxidative stress within living systems. Nanoceria dissolution occurs in acidic environments. Nanoceria stabilization is a known problem even during its synthesis; in fact, a carboxylic acid, namely citric acid, is used in many synthesis protocols. Citric acid adsorbs onto nanoceria surfaces, limiting particle formation and creating stable dispersions with extended shelf life. To better understand factors influencing the fate of nanoceria, its dissolution and stabilization have been previously studied in vitro using acidic aqueous environments. Nanoceria agglomerated in the presence of some carboxylic acids over 30 weeks, and degraded in others, at pH 4.5 (i.e., the pH value in phagolysosomes). Plants release carboxylic acids, and cerium carboxylates are found in underground and aerial plant parts. To further test nanoceria stability, suspensions were exposed to light and dark conditions, simulating plant environments and biological systems. Light induced nanoceria agglomeration in the presence of some carboxylic acids. Nanoceria agglomeration did not occur in the dark in the presence of most carboxylic acids. Light initiates free radicals generated by ceria nanoparticles. Nanoceria completely dissolved in the presence of citric, malic, and isocitric acid when exposed to light, attributed to nanoceria dissolution, release of Ce3+ ions, and formation of cerium coordination complexes on the ceria nanoparticle surface that inhibit agglomeration. Key functional groups of carboxylic acids that prevented nanoceria agglomeration were identified. A long carbon chain backbone containing a carboxylic acid group geminal to a hydroxy group in addition to a second carboxylic acid group may optimally complex with nanoceria. The results provide mechanistic insight into the role of carboxylic acids in nanoceria dissolution and its fate in soils, plants, and biological systems.

Single Atom-Engineered NIR-II Gold Clusters with Ultrahigh Brightness and Stability for Acute Kidney Injury

Near-infrared-II (NIR-II) imaging has shown great potential for monitoring the pathological progression and deep tissue imaging but is limited to present unmet NIR-II agent. Present fluorophores show a promising prospect for NIR-II imaging, but brightness and photostability are still highly challenging during real-time monitoring. In this work, atom-engineered NIR-II Au₂₄ Cd₁  clusters with ultrahigh brightness, stability, and photostability are developed via single atomic Cd doping. Single atom Cd substitutions contribute to Cd 4d state in HOMO and redistribution of energy level near the gap, exhibiting 56-fold fluorescence enhancement of Au₂₄ Cd₁  clusters. Meanwhile, single atomic Cd reinforces CdAu bond energy, formation energy, and stabilized cluster structure, leading to persistent stability for up to 1 month without decay, as well as excellent photostability of 1 h without photobleaching, much longer than clinically approved indocyanine green (<5 min). In vivo imaging shows gold clusters can monitor acute kidney injury (AKI) even after 72 h of injury, enabling evaluating progression at a very long window. Meanwhile, the bioactive gold clusters can alleviate AKI-induced oxidative stress damage and acute neuroinflammation. Single atom-engineered gold clusters exhibit molecular tracking and diagnostic prospect in kidney-related diseases.

The effect of cerium dioxide nanoparticles on the viability of hippocampal neurons in Alzheimer’s disease modeling

The possibilities of using nanoparticle materials based on cerium dioxide (CNPs) are exciting since they are low toxic and have specific redox, antiradical properties. It can be supposed that CNPs’ biomedical use is also relevant in neurodegenerative diseases, especially Alzheimer’s disease (AD). AD is known as the pathologies leading to progressive dementia in the elderly. The factor that provokes nerve cell death and cognitive impairment in AD is the pathological accumulation of beta-amyloid peptide (Aβ) in the brain tissue. In our studies, we examined the impact of Aβ 1-42 on neuronal death and evaluated the potential neuroprotective properties of CNPs during AD modeling in cell culture. Our findings show that, under AD modeling conditions, the number of necrotic neurons increased from 9.4% in the control to 42.7% when Aβ 1-42 was used. In contrast, CNPs alone showed low toxicity, with no significant increase in the number of necrotic cells compared to control conditions. We further explored the potential of CNPs as a neuroprotective agent against Aβ-induced neuronal death. We found that introducing CNPs 24 h after Aβ 1-42 incubation or prophylactically incubating hippocampal cells with CNPs 24 h before amyloid administration significantly reduced the percentage of necrotic cells to 17.8 and 13.3%, respectively. Our results suggest that CNPs in the cultural media can significantly reduce the number of dead hippocampal neurons in the presence of Aβ, highlighting their neuroprotective properties. These findings suggest that CNPs may hold promise for developing new treatments for AD based on their neuroprotective properties.

Modulation of the biocatalytic activity and selectivity of CeO2 nanozymes via atomic doping engineering

Artificial enzymes show prospects in biomedical applications due to their stable enzymatic catalytic activity and ease of preparation. CeO₂ nanozymes represent a versatile platform showing multiple enzyme-mimicking activities, although their biocatalytic activities and selectivity are relatively poor for biomedical use. Herein, we developed Mn- and Co-doped CeO₂ nanozymes (M/CeO₂, M = Mn or Co) via atomic engineering to achieve a significant increase in enzyme-like activity. The M/CeO₂ nanozymes exhibited outstanding peroxidase-like activity with a reaction rate about 8-10 times higher than that of CeO₂. Importantly, the Co/CeO₂ nanozyme preferred for catalase-like activity with a 4-6-fold higher catalytic rate than CeO₂, while the Mn/CeO₂ nanozyme had a predilection for improving the superoxide dismutase-like capacity. This indicated the selective modulation of enzyme-mimicking activities via atomic doping engineering. Cellular level experiments revealed the in vitro therapeutic effects of the nanozymes. Mn/CeO₂ and Co/CeO₂ selectively modulated the intracellular redox imbalance in lipopolysaccharide (LPS)- or H₂O₂-stimulated nerve cells and improved cell survival. This work provides a feasible strategy for the design of catalytically selective artificial enzymes and facilitates the widespread application of CeO₂ nanozymes in redox-related diseases.

Cerium-Doped Self-Assembling Nanoparticles as a Novel Anti-Oxidant Delivery System Preserving Mitochondrial Function in Cortical Neurons Exposed to Ischemia-like Conditions

Neurodegenerative diseases are characterized by mitochondrial dysfunction leading to abnormal levels of reactive oxygen species (ROS), making the use of ROS-scavenging nanomaterials a promising therapeutic approach. Here, we combined the unique ROS-scavenging properties of cerium-based nanomaterials with the lipid self-assembling nanoparticles (SANP) technology. We optimized the preparation of cerium-doped SANP (Ce-SANP) and characterized the formulations in terms of both physiochemical and biological properties. Ce-SANP exhibited good colloidal properties and were able to mimic the activity of two ROS-scavenging enzymes, namely peroxidase and super oxide dismutase. Under ischemia-like conditions, Ce-SANP could rescue neuronal cells from mitochondrial suffering by reducing ROS production and preventing ATP level reduction. Furthermore, Ce-SANP prevented mitochondrial Ca²⁺ homeostasis dysfunction, partially restoring mitochondrial Ca²⁺ handling. Taken together, these results highlight the potential of the anti-oxidant Ce-SANP platform technology to manage ROS levels and mitochondrial function for the treatment of neurodegenerative diseases.

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

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

Noninvasive Delivery of Self-Regenerating Cerium Oxide Nanoparticles to Modulate Oxidative Stress in the Retina

Diseases affecting the retina, such as age-related macular degeneration (AMD), diabetic retinopathy, macular edema, and retinal vein occlusions, are currently treated by the intravitreal injection of drug formulations. These disease pathologies are driven by oxidative damage due to chronic high concentrations of reactive oxygen species (ROS) in the retina. Intravitreal injections often induce retinal detachment, intraocular hemorrhage, and endophthalmitis. Furthermore, the severe eye pain associated with these injections lead to patient noncompliance and treatment discontinuation. Hence, there is a critical need for the development of a noninvasive therapy that is effective for a prolonged period for treating retinal diseases. In this study, we developed a noninvasive cerium oxide nanoparticle (CNP) delivery wafer (Cerawafer) for the modulation of ROS in the retina. We fabricated Cerawafer loaded with CNP and determined its SOD-like enzyme-mimetic activity and ability to neutralize ROS generated in vitro. We demonstrated Cerawafer's ability to deliver CNP in a noninvasive fashion to the retina in healthy mouse eyes and the CNP retention in the retina for more than a week. Our studies have demonstrated the in vivo efficacy of the Cerawafer to modulate ROS and associated down-regulation of VEGF expression in the retinas of very-low-density lipoprotein receptor knockout (vldlr-/-) mouse model. The development of a Cerawafer nanotherapeutic will fulfill a hitherto unmet need. Currently, there is no such therapeutic available, and the development of a Cerawafer nanotherapeutic will be a major advancement in the treatment of retinal diseases.

Nanozymes in the Treatment of Diseases Caused by Excessive Reactive Oxygen Specie

Excessive reactive oxygen species (ROS) may generate deleterious effects on biomolecules, such as DNA damage, protein oxidation and lipid peroxidation, causing cell and tissue damage and eventually leading to the pathogenesis of diseases, such as neurodegenerative diseases, ischemia/reperfusion ((I/R)) injury, and inflammatory diseases. Therefore, the modulation of ROS can be an efficient means to relieve the aforementioned diseases. Several studies have verified that antioxidants such as Mitoquinone (a mitochondrial-targeted coenzyme Q10 derivative) can scavenge ROS and attenuate related diseases. Nanozymes, defined as nanomaterials with intrinsic enzyme-like properties that also possess antioxidant properties, are hence expected to be promising alternatives for the treatment of ROS-related diseases. This review introduces the types of nanozymes with inherent antioxidant activities, elaborates on various strategies (eg, controlling the size or shape of nanozymes, regulating the composition of nanozymes and environmental factors) for modulating their catalytic activities, and summarizes their performances in treating ROS-induced diseases.

Structural, Optical, Antibacterial, and Anticancer Properties of Cerium Oxide Nanoparticles Prepared by Green Synthesis Using Morinda citrifolia Leaves Extract

Currently, new advancements in the area of nanotechnology opened up new prospects in the field of medicine that could provide us with a solution for numerous medical complications. Although a several varieties of nanoparticles is being explored to be used as nanomedicines, cerium oxide nanoparticles (CeO2 NPs) are the most attractive due to their biocompatibility and their switchable oxidation state (+3 and +4) or in other words the ability to act as prooxidant and antioxidant depending on the pH condition. Green synthesis of nanoparticles is preferred to make it more economical, eco-friendly, and less toxic. The aim of our study here is to formulate the CeO2 NPs (CeO2 NPs) using Morinda citrifolia (Noni) leaf extract and study its optical, structural, antibacterial, and anticancer abilities. Their optical and structural characterization was accomplished by employing X-ray diffractography (XRD), TEM, EDAX, FTIR, UV-vis, and photoluminescence assays. Our CeO2 NPs expressed strong antibacterial effects against Gram-positive S. aureus and S. pneumonia in addition to Gram-negative E. coli and K. pneumonia when compared with amoxicillin. The anticancer properties of the green synthesized CeO2 NPs against human acute lymphoblastic leukemia (ALL) MOLT-4 cells were further explored by the meticulous study of their ability to diminish cancer cell viability (cytotoxicity), accelerate apoptosis, escalate intracellular reactive oxygen species (ROS) accumulation, decline the mitochondria membrane potential (MMP) level, modify the cell adhesion, and shoot up the activation of proapoptotic markers, caspase-3, -8, and -9, in the tumor cells. Altogether, the outcomes demonstrated that our green synthesized CeO2 NPs are an excellent candidate for alternative cancer therapy.

Activation of SIRT-1 Pathway by Nanoceria Sheds Light on Its Ameliorative Effect on Doxorubicin-Induced Cognitive Impairment (Chemobrain): Restraining Its Neuroinflammation, Synaptic Dysplasticity and Apoptosis

Chemo fog is one of the most serious health concerns encountered by cancer survivors receiving doxorubicin (DOX)-based chemotherapy. Oxidative stress, neuroinflammation, apoptosis and impairment of synaptic plasticity are regarded as the key factors implicated in DOX-induced cognitive impairment. This research aimed to assess the possible neuroprotective effect of cerium oxide nanoparticles (CeNPs) against DOX-induced neurotoxicity. Forty-eight rats were divided into four groups (12 rats/group): control group, CeNPs group (received oral CeNPs solution (35 mg/kg) daily for 4 weeks), and DOX group (were administered DOX intraperitoneally (2 mg/kg, once/week for 4 weeks)) and DOX+ CeNPs group. The findings revealed that CeNPs mitigated behavioral alterations in DOX-induced cognitive deficit. Additionally, CeNPs alleviated the histopathological abnormalities in hippocampus and ameliorated DOX-induced neuroinflammation by downregulating the expression of NF-κB, TNF-α, IL-1β and IL6. In addition, CeNPs antagonized the apoptosis through reducing the protein expression of cytochrome c and caspase 3. In addition, it stimulated the antioxidant defense, as indicated by upregulating the expression of the Nrf2, HO-1 and PGC-1α genes. CeNPs improved synaptic plasticity via acting on the BDNF. These actions were related through the modification of SIRT-1 expression. Based on the aforementioned results, CeNPs antagonized the doxorubicin-induced neurodegeneration by its antioxidant, anti-inflammatory and antiapoptotic effects, alongside its SIRT-1 mediated mechanisms.

Harnessing immune response using reactive oxygen Species-Generating/Eliminating inorganic biomaterials for disease treatment

With the increasing understanding of various biological functions mediated by reactive oxygen species (ROS) in the immune system, a number of studies have been designed to develop ROS-generating/eliminating strategies to selectively modulate immunogenicity for disease treatment. These strategies potentially exploit ROS-modulating inorganic biomaterials to harness host immunity to maximize the therapeutic potency by eliciting a favorable immune response. Inorganic biomaterial-guided in vivo ROS scavenging can exhibit several effects to: i) reduce the secretion of pro-inflammatory factors, ii) induce the phenotypic transition of macrophages from inflammatory M1 to immunosuppressive M2 phase, iii) minimize the recruitment and infiltration of immune cells. and/or iv) suppress the activation of nuclear factor kappa-B (NF-κB) pathway. Inversely, ROS-generating inorganic biomaterials have been found to be capable of: i) inducing immunogenic cell death (ICD), ii) reprograming tumor-associated macrophages from M2 to M1 phenotypes, iii) activating inflammasomes to stimulate tumor immunogenicity, and/or iv) recruiting phagocytes for antimicrobial therapy. This review provides a systematic and up-to-date overview on the progress related to ROS-nanotechnology mediated immunomodulation. We highlight how the ROS-generating/eliminating inorganic biomaterials can converge with immunomodulation and ultimately elicit an effective immune response against inflammation, autoimmune diseases, and/or cancers. We expect that contents presented in this review will be beneficial for the future advancements of ROS-based nanotechnology and its potential applications in this evolving field.

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.

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.

NIR-II-Responsive CeO2-x@HA Nanotheranostics for Photoacoustic Imaging-Guided Sonodynamic-Enhanced Synergistic Phototherapy

The therapeutic effect of photothermal therapy (PTT) and photodynamic therapy (PDT) is severely limited because of the shallow tissue penetration depth of the first near-infrared (NIR-I) light. Multifunctional nanotheranostics irradiated by the second near-infrared (NIR-II) light have received wide interest with respect to deeper tissue penetration, and sonodynamic therapy (SDT) synergistic phototherapy can achieve the complete elimination of tumors. Herein, we successfully constructed a single NIR-II light-induced nanotheranostic using cerium oxide (CeO_2-x) with abundant oxygen vacancies for photoacoustic imaging-guided SDT-enhanced phototherapy for the first time. CeO_2-x with surface crystalline disorder showed extensive NIR-II region absorption and an outstanding photothermal conversion ability. In addition, the CeO_2-x layer with numerous oxygen defects can promote the separation of holes and electrons by ultrasound irradiation, which can remarkably enhance the efficacy of phototherapy to achieve high-efficiency tumor ablation. CeO_2-x was surface modified with hyaluronic acid (HA) to prepare CeO_2-x@HA to allow active tumor targeting efficiency. Both cell and animal experiments confirmed that all-in-one CeO_2-x@HA exhibited a high therapeutic efficacy of SDT-enhanced PDT/PTT under 1064 nm laser irradiation, which achieved complete tumor eradication without systemic toxicity. This study significantly broadened the application of NIR-II-responsive CeO_2-x for photoacoustic imaging-mediated SDT-enhanced phototherapy to the highly efficient and precise elimination of tumors.

Targeted Delivery Platforms for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative condition of the central nervous system (CNS) that presents with varying levels of disability in patients, displaying the significance of timely and effective management of this complication. Though several treatments have been developed to protect nerves, comprehensive improvement of MS is still considered an essential bottleneck. Therefore, the development of innovative treatment methods for MS is one of the core research areas. In this regard, nanoscale platforms can offer practical and ideal approaches to the diagnosis and treatment of various diseases, especially immunological disorders such as MS, to improve the effectiveness of conventional therapies. It should be noted that there is significant progress in the development of neuroprotective strategies through the implementation of various nanoparticles, monoclonal antibodies, peptides, and aptamers. In this study, we summarize different particle systems as well as targeted therapies, such as antibodies, peptides, nucleic acids, and engineered cells for the treatment of MS, and discuss their potential in the treatment of MS in the preclinical and clinical stages. Future advances in targeted delivery of medical supplies may offer new strategies for complete recovery as well as practical treatment of progressive forms of MS.

Europium-Doped Cerium Oxide Nanoparticles for Microglial Amyloid Beta Clearance and Homeostasis

Alzheimer's disease (AD) is the most common neurodegenerative disorder. Pathologically, the disease is characterized by the deposition of amyloid beta (Aβ) plaques and the presence of neurofibrillary tangles. These drive microglia neuroinflammation and consequent neurodegeneration. While the means to affect Aβ plaque accumulation pharmacologically was achieved, how it affects disease outcomes remains uncertain. Cerium oxide (CeO₂) reduces Aβ plaques, oxidative stress, inflammation, and AD signs and symptoms. In particular, CeO₂ nanoparticles (CeO₂NPs) induce free-radical-scavenging and cell protective intracellular signaling. This can ameliorate the pathobiology of an AD-affected brain. To investigate whether CeO₂NPs affect microglia neurotoxic responses, a novel formulation of europium-doped CeO₂NPs (EuCeO₂NPs) was synthesized. We then tested EuCeO₂NPs for its ability to generate cellular immune homeostasis in AD models. EuCeO₂NPs attenuated microglia BV2 inflammatory activities after Aβ_1-42 exposure by increasing the cells' phagocytic and Aβ degradation activities. These were associated with increases in the expression of the CD36 scavenger receptor. EuCeO₂NPs facilitated Aβ endolysosomal trafficking and abrogated microglial inflammatory responses. We posit that EuCeO₂NPs may be developed as an AD immunomodulator.

Potential nanotherapeutic strategies for perioperative stroke

AIMS

Based on the complex pathological environment of perioperative stroke, the development of targeted therapeutic strategies is important to control the development of perioperative stroke.

DISCUSSIONS

Recently, great progress has been made in nanotechnology, and nanodrug delivery systems have been developed for the treatment of ischemic stroke.

CONCLUSION

In this review, the pathological processes and mechanisms of ischemic stroke during perioperative stroke onset were systematically sorted. As a potential treatment strategy for perioperative stroke, the review also summarizes the multifunctional nanodelivery systems based on ischemic stroke, thus providing insight into the nanotherapeutic strategies for perioperative stroke.

Effects of subchronic dietary exposure to the engineered nanomaterials SiO2 and CeO2 in C57BL/6J and 5xFAD Alzheimer model mice

Background

There is an increasing concern about the neurotoxicity of engineered nanomaterials (NMs). To investigate the effects of subchronic oral exposures to SiO₂ and CeO₂ NMs on Alzheimer’s disease (AD)-like pathology, 5xFAD transgenic mice and their C57BL/6J littermates were fed ad libitum for 3 or 14 weeks with control food pellets, or pellets dosed with these respective NMs at 0.1% or 1% (w/w). Behaviour effects were evaluated by X-maze, string suspension, balance beam and open field tests. Brains were analysed for plaque load, beta-amyloid peptide levels, markers of oxidative stress and neuroinflammation.

Results

No marked behavioural impairments were observed in the mice exposed to SiO₂ or CeO₂ and neither treatment resulted in accelerated plaque formation, increased oxidative stress or inflammation. In contrast, the 5xFAD mice exposed to 1% CeO₂ for 14 weeks showed significantly lower hippocampal Aβ plaque load and improved locomotor activity compared to the corresponding controls.

Conclusions

The findings from the present study suggest that long-term oral exposure to SiO₂ or CeO₂ NMs has no neurotoxic and AD-promoting effects. The reduced plaque burden observed in the mice following dietary CeO₂ exposure warrants further investigation to establish the underlying mechanism, given the easy applicability of this administration method.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00461-2.

How Does Immunomodulatory Nanoceria Works? ROS and Immunometabolism

Dysregulation of the immune system is associated with an overproduction of metabolic reactive oxygen species (ROS) and consequent oxidative stress. By buffering excess ROS, cerium oxide (CeO₂) nanoparticles (NPs) (nanoceria) not only protect from oxidative stress consequence of inflammation but also modulate the immune response towards inflammation resolution. Immunomodulation is the modulation (regulatory adjustment) of the immune system. It has natural and human-induced forms, and it is part of immunotherapy, in which immune responses are induced, amplified, attenuated, or prevented according to therapeutic goals. For decades, it has been observed that immune cells transform from relative metabolic quiescence to a highly active metabolic state during activation(1). These changes in metabolism affect fate and function over a broad range of timescales and cell types, always correlated to metabolic changes closely associated with mitochondria number and morphology. The question is how to control the immunochemical potential, thereby regulating the immune response, by administering cellular power supply. In this regard, immune cells show different general catabolic modes relative to their activation status, linked to their specific functions (maintenance, scavenging, defense, resolution, and repair) that can be correlated to different ROS requirements and production. Properly formulated, nanoceria is highly soluble, safe, and potentially biodegradable, and it may overcome current antioxidant substances limitations and thus open a new era for human health management.

Novel fabrication of bi-metal oxide hybrid nanocomposites for synergetic enhancement of in vivo healing and wound care after caesarean section surgery

In the current study, bi‐metal oxide hybrid nanocomposites prepared by cerium oxide (CeO₂) nanoparticles are included into chitosan‐ZnO composites for developing the potential materials of dressing the wound. The wound healing effect of prepared hybrid nanocomposites was evaluated regarding the surface morphology, functional groups, thermal degradation and composite size. The antimicrobial activity of chitosan‐ZnO/CeO₂ hybrid nano composites was tested against the pathogens of Staphylococcus aureus and Escherichia coli. The hybrid nanocomposites containing CeO₂‐based chitosan and ZnO nanoparticles were taken for optimum dressing included in the vivo studies on the excisional wounds in wistar rats. After 2 weeks, it is seen that the wound treated with CS‐ZnO/CeO₂ hybrid nano composites consists of the significant dressing of nearly 100% compared with control which showed nearly 65% of wound closure. Finally, our reported results gave the proof in supporting the availability of CS‐ZnO/CeO₂ hybrid nanocomposites contains the dressing of the wounds for the treatment.

Nanotherapeutics and the Brain

Brain disease remains a significant health, social, and economic burden with a high failure rate of translation of therapeutics to the clinic. Nanotherapeutics have represented a promising area of technology investment to improve drug bioavailability and delivery to the brain, with several successes for nanotherapeutic use for central nervous system disease that are currently in the clinic. However, renewed and continued research on the treatment of neurological disorders is critically needed. We explore the challenges of drug delivery to the brain and the ways in which nanotherapeutics can overcome these challenges. We provide a summary and overview of general design principles that can be applied to nanotherapeutics for uptake and penetration in the brain. We next highlight remaining questions that limit the translational potential of nanotherapeutics for application in the clinic. Lastly, we provide recommendations for ongoing preclinical research to improve the overall success of nanotherapeutics against neurological disease. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering, Volume 13 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Recent advancements in nanoparticle-mediated approaches for restoration of multiple sclerosis

Multiple Sclerosis (MS) is an autoimmune disease with complicated immunopathology which necessitates considering multifactorial aspects for its management. Nano-sized pharmaceutical carriers named nanoparticles (NPs) can support impressive management of disease not only in early detection and prognosis level but also in a therapeutic manner. The most prominent initiator of MS is the domination of cellular immunity to humoral immunity and increment of inflammatory cytokines. The administration of several platforms of NPs for MS management holds great promise so far. The efforts for MS management through in vitro and in vivo (experimental animal models) evaluations, pave a new way to a highly efficient therapeutic means and aiding its translation to the clinic in the near future.

Ultrasmall Antioxidant Cerium Oxide Nanoparticles for Regulation of Acute Inflammation

Cerium oxide nanoparticles (CeONP), having potent antioxidant properties, are highly promising nanomaterials for treatment of diseases in which oxidative stress from excessive reactive oxygen species (ROS) plays a critical role in the pathogenesis and progression. However, most previously reported CeONP formulations were not efficiently cleared from the body, precluding their clinical translation. Herein, we report ultrasmall CeONP that can mitigate activation of macrophages and subsequent acute inflammation. It is found that these CeONP can effectively scavenge reactive species, inhibit macrophage activation, and minimize their recruitment and infiltration to the inflammation site, which lead to alleviation of edema and pain hypersensitivity. Moreover, we demonstrate that CeONP can be effectively excreted from the body within 24 h of systemic administration, minimizing long-term toxicity concerns. Altogether, our findings suggest that CeONP may be explored as both antioxidant and anti-inflammatory agents that can reduce acute inflammation with a better safety profile than existing nanoparticles.

The use of cerium oxide nanoparticles in liver disorders: A double-sided coin?

Being recognized as the first antioxidant nanoparticles (NPs) proposed for medicine, cerium oxide nanoparticles (CeO₂ NPs) have recently gained tremendous attention for their vast biomedical applications. Nevertheless, inconsistent reports of either medical benefits or toxicity have created an atmosphere of uncertainty hindering their clinical utilization. Like other nanoparticles advocated as a promising protective/therapeutic option, CeO₂ NPs are sometimes questioned as a health threat. As CeO₂ NPs tend to accumulate in the liver after intravenous injection, liver is known to represent the key tissue to test for their therapeutic/toxicological effects. However, more research evidence is still needed before any conclusions can be elicited about the mechanisms by which CeO₂ NPs could be harmful or protective/therapeutic to the liver tissue. A proper understanding of such discrepancies is warranted to plan for further modifications to mitigate any side effects. Therefore, in this MiniReview, we tried to demonstrate the two sides of the same coin, CeO₂ NPs, within the liver context. As well, we highlighted a few promising strategies by which the negatives of CeO₂ NPs could be diminished while enhancing all the positives.

Nanotechnology-Based Drug Delivery Strategies to Repair the Mitochondrial Function in Neuroinflammatory and Neurodegenerative Diseases

Mitochondria are vital organelles in eukaryotic cells that control diverse physiological processes related to energy production, calcium homeostasis, the generation of reactive oxygen species, and cell death. Several studies have demonstrated that structural and functional mitochondrial disturbances are involved in the development of different neuroinflammatory (NI) and neurodegenerative (ND) diseases (NI&NDDs) such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Remarkably, counteracting mitochondrial impairment by genetic or pharmacologic treatment ameliorates neurodegeneration and clinical disability in animal models of these diseases. Therefore, the development of nanosystems enabling the sustained and selective delivery of mitochondria-targeted drugs is a novel and effective strategy to tackle NI&NDDs. In this review, we outline the impact of mitochondrial dysfunction associated with unbalanced mitochondrial dynamics, altered mitophagy, oxidative stress, energy deficit, and proteinopathies in NI&NDDs. In addition, we review different strategies for selective mitochondria-specific ligand targeting and discuss novel nanomaterials, nanozymes, and drug-loaded nanosystems developed to repair mitochondrial function and their therapeutic benefits protecting against oxidative stress, restoring cell energy production, preventing cell death, inhibiting protein aggregates, and improving motor and cognitive disability in cellular and animal models of different NI&NDDs.

Nanoceria, the versatile nanoparticles: Promising biomedical applications

Nanotechnology has been a boon for the biomedical field due to the freedom it provides for tailoring of pharmacokinetic properties of different drug molecules. Nanomedicine is the medical application of nanotechnology for the diagnosis, treatment and/or management of the diseases. Cerium oxide nanoparticles (CNPs) are metal oxide-based nanoparticles (NPs) which possess outstanding reactive oxygen species (ROS) scavenging activities primarily due to the availability of "oxidation switch" on their surface. These NP have been found to protect from a number of disorders with a background of oxidative stress such as cancer, diabetes etc. In fact, the CNPs have been found to possess the environment-dependent ROS modulating properties. In addition, the inherent catalase, SOD, oxidase, peroxidase and phosphatase mimetic properties of CNPs provide them superiority over a number of NPs. Further, chemical reactivity of CNPs seems to be a function of their surface chemistry which can be precisely tuned by defect engineering. However, the contradictory reports make it necessary to critically evaluate the potential of CNPs, in the light of available literature. The review is aimed at probing the feasibility of CNPs to push towards the clinical studies. Further, we have also covered and censoriously discussed the suspected negative impacts of CNPs before making our way to a consensus. This review aims to be a comprehensive, authoritative, critical, and accessible review of general interest to the scientific community.

Shape effect of cerium oxide nanoparticles on mild traumatic brain injury

The catalytic performance and therapeutic effect of nanoparticles varies with shape. Here, we investigated and compared the therapeutic outcomes of ceria nanospheres (Ceria NSs) and ceria nanorods (Ceria NRs) in an in vivo study of mild traumatic brain injury (mTBI). In vivo TBI was induced in a mouse model of open head injury using a stereotaxic impactor. Outcomes including cytoprotective effects, cognitive function, and cerebral edema were investigated after retro-orbital injection of 11.6 mM of ceria nanoparticles. Ceria nanoparticles significantly reduced fluoro-jade B (FJB)-positive cells and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells, and restored mRNA levels of superoxide dismutase 1 (SOD1) and SOD2. They also decreased the cyclooxygenase-2 (COX-2) expression compared with the untreated control group. Comparing the two nanomaterials, Ceria NRs showed less stable and high-energy (100) and (110) planes, which increased the number of active sites. The Ce3+/Ce4+ molar ratio of Ceria NRs (0.40) was greater than that of Ceria NSs (0.27). Ceria NRs (0.059 ± 0.021) appeared to exhibit better anti-inflammatory effect than Ceria NSs (0.133 ± 0.024), but the effect was statistically insignificant (p = 0.190). Ceria nanoparticles also improved cognitive impairment following mTBI compared with the control group, but the effect did not differ significantly according to the nanoshape. However, Ceria NRs (70.1 ± 0.5%) significantly decreased brain water content compared with Ceria NSs (73.7 ± 0.4%; p = 0.0015), indicating a more effective reduction in brain edema (p = 0.0015). Compared with Ceria NSs, the Ceria NRs are more effective in alleviating cerebral edema following in vivo mTBI.

Antioxidant Activity and Toxicity Study of Cerium Oxide Nanoparticles Stabilized with Innovative Functional Copolymers

Oxidative stress, which is one of the main harmful mechanisms of pathologies including ischemic stroke, contributes to both neurons and endothelial cell damages, leading to vascular lesions. Although many antioxidants are tested in preclinical studies, no treatment is currently available for stroke patients. Since cerium oxide nanoparticles (CNPs) exhibit remarkable antioxidant capacities, the objective is to develop an innovative coating to enhance CNPs biocompatibility without disrupting their antioxidant capacities or enhance their toxicity. This study reports the synthesis and characterization of functional polymers and their impact on the enzyme-like catalytic activity of CNPs. To study the toxicity and the antioxidant properties of CNPs for stroke and particularly endothelial damages, in vitro studies are conducted on a cerebral endothelial cell line (bEnd.3). Despite their internalization in bEnd.3 cells, coated CNPs are devoid of cytotoxicity. Microscopy studies report an intracellular localization of CNPs, more precisely in endosomes. All CNPs reduces glutamate-induced intracellular production of reactive oxygen species (ROS) in endothelial cells but one CNP significantly reduces both the production of mitochondrial superoxide anion and DNA oxidation. In vivo studies report a lack of toxicity in mice. This study therefore describes and identifies biocompatible CNPs with interesting antioxidant properties for ischemic stroke and related pathologies.

Physiological and Pathological Factors Affecting Drug Delivery to the Brain by Nanoparticles

The prevalence of neurological/neurodegenerative diseases, such as Alzheimer's disease is known to be increasing due to an aging population and is anticipated to further grow in the decades ahead. The treatment of brain diseases is challenging partly due to the inaccessibility of therapeutic agents to the brain. An increasingly important observation is that the physiology of the brain alters during many brain diseases, and aging adds even more to the complexity of the disease. There is a notion that the permeability of the blood-brain barrier (BBB) increases with aging or disease, however, the body has a defense mechanism that still retains the separation of the brain from harmful chemicals in the blood. This makes drug delivery to the diseased brain, even more challenging and complex task. Here, the physiological changes to the diseased brain and aged brain are covered in the context of drug delivery to the brain using nanoparticles. Also, recent and novel approaches are discussed for the delivery of therapeutic agents to the diseased brain using nanoparticle based or magnetic resonance imaging guided systems. Furthermore, the complement activation, toxicity, and immunogenicity of brain targeting nanoparticles as well as novel in vitro BBB models are discussed.

Preclinical studies conducted on nanozyme antioxidants: shortcomings and challenges based on US FDA regulations

The wide prevalence of oxidative stress-induced diseases has led to a growing demand for antioxidant therapeutics worldwide. Nanozyme antioxidants are drawing enormous attention as practical alternatives for conventional antioxidants. The considerable body of research over the last decade and the promising results achieved signify the potential of nanozyme antioxidants to secure a place in the expanding market of antioxidant therapeutics. Nonetheless, there is no report on clinical trials for their further evaluation. Through analyzing in-depth selected papers which have conducted in vivo studies on nanozyme antioxidants, this review aims to pinpoint and discuss possible reasons impeding development of research toward clinical studies and to offer some practical solutions for future studies to bridge the gap between preclinical and clinical stages.

Cerium oxide nanoparticles protect against irradiation-induced cellular damage while augmenting osteogenesis

Increased bone loss and risk of fracture are two of the main challenges for cancer patients who undergo ionizing radiation (IR) therapy. This decline in bone quality is in part, caused by the excessive and sustained release of reactive oxygen species (ROS). Cerium oxide nanoparticles (CeONPs) have proven antioxidant and regenerative properties and the purpose of this study was to investigate the effect of CeONPs in reducing IR-induced functional damage in human bone marrow-derived mesenchymal stromal cells (hBMSCs). hBMSCs were supplemented with CeONPs at a concentration of either 1 or 10 μg/mL 24 h prior to exposure to a single 7 Gy irradiation dose. ROS levels, cellular proliferation, morphology, senescence, DNA damage, p53 expression and autophagy were evaluated as well as alkaline phosphatase, osteogenic protein gene expression and bone matrix deposition following osteogenic differentiation. Results showed that supplementation of CeONPs at a concentration of 1 μg/mL reduced cell senescence and significantly augmented cell autophagy (p = 0.01), osteogenesis and bone matrix deposition >2-fold (p = 0.0001) while under normal, non-irradiated culture conditions. Following irradiation, functional damage was attenuated and CeONPs at both 1 or 10 μg/mL significantly reduced ROS levels (p = 0.05 and 0.001 respectively), DNA damage by >4-fold (p < 0.05) while increasing autophagy >3.5-fold and bone matrix deposition 5-fold (p = 0.0001 in both groups). When supplemented with 10 μg/mL, p53 expression increased 3.5-fold (p < 0.05). We conclude that cellular uptake of CeONPs offered a significant, multifunctional and protective effect against IR-induced cellular damage while also augmenting osteogenic differentiation and subsequent new bone deposition. The use of CeONPs holds promise as a novel multifunctional therapeutic strategy for irradiation-induced bone loss.

Complexity of the Nano-Bio Interface and the Tortuous Path of Metal Oxides in Biological Systems

Metal oxide nanoparticles (NPs) have received a great deal of attention as potential theranostic agents. Despite extensive work on a wide variety of metal oxide NPs, few chemically active metal oxide NPs have received Food and Drug Administration (FDA) clearance. The clinical translation of metal oxide NP activity, which often looks so promising in preclinical studies, has not progressed as rapidly as one might expect. The lack of FDA approval for metal oxide NPs appears to be a consequence of the complex transformation of NP chemistry as any given NP passes through multiple extra- and intracellular environments and interacts with a variety of proteins and transport processes that may degrade or transform the chemical properties of the metal oxide NP. Moreover, the translational models frequently used to study these materials do not represent the final therapeutic environment well, and studies in reduced preparations have, all too frequently, predicted fundamentally different physico-chemical properties from the biological activity observed in intact organisms. Understanding the evolving pharmacology of metal oxide NPs as they interact with biological systems is critical to establish translational test systems that effectively predict future theranostic activity.