Cerium oxide nanoparticles accelerate the decay of peroxynitrite (ONOO(-))

Periodic Table of Immunomodulatory Elements and Derived Two-Dimensional Biomaterials

Periodic table of chemical elements serves as the foundation of material chemistry, impacting human health in many different ways. It contributes to the creation, growth, and manipulation of functional metallic, ceramic, metalloid, polymeric, and carbon-based materials on and near an atomic scale. Recent nanotechnology advancements have revolutionized the field of biomedical engineering to tackle longstanding clinical challenges. The use of nano-biomaterials has gained traction in medicine, specifically in the areas of nano-immunoengineering to treat inflammatory and infectious diseases. Two-dimensional (2D) nanomaterials have been found to possess high bioactive surface area and compatibility with human and mammalian cells at controlled doses. Furthermore, these biomaterials have intrinsic immunomodulatory properties, which is crucial for their application in immuno-nanomedicine. While significant progress has been made in understanding their bioactivity and biocompatibility, the exact immunomodulatory responses and mechanisms of these materials are still being explored. Current work outlines an innovative "immunomodulatory periodic table of elements" beyond the periodic table of life, medicine, and microbial genomics and comprehensively reviews the role of each element in designing immunoengineered 2D biomaterials in a group-wise manner. It recapitulates the most recent advances in immunomodulatory nanomaterials, paving the way for the development of new mono, hybrid, composite, and hetero-structured biomaterials.

Functionalized metal oxide nanoparticles: A promising intervention against major health burden of diseases

Metal oxide nanoparticles (MONPs) is one of the most effective materials for medical applications with their substantial surface metallic ions and high surface area-volume ratio. Over decades, MONPs have been considered potential treatments due to their demonstrated ability and reactivity to target diverse cellular signaling pathways implicated in antimicrobial effects, as well as in the amelioration of oxidative stress, inflammation, cancer progression, and glucose together with lipid dysregulation. Based on their unique characteristics, MONPs have shown to be biodegradable and biocompatible vehicles for drugs, which have recently been applied in drug delivery as nanocarriers to enhance their delivery capacity for mechanistic membrane transport. However, little is known about the precise cellular responses, molecular mechanisms, and potential use of MONPs in the medical field. This review emphasizes on elaborating the biochemical reactivities of MONPs on molecular and cellular reactions, highlighting the physiological responses, mechanisms of action, certain drawbacks, and remediation of these functionalized materials. The significant goal of this literature is to shed light on the new perspectives of MONPs in pre-clinical application to pursue for clinical research as alternative-personalized medicines to prevent individuals from drastic diseases.

Oxidative stress modulating nanomaterials and their biochemical roles in nanomedicine

Many pathological conditions are predominantly associated with oxidative stress, arising from reactive oxygen species (ROS); therefore, the modulation of redox activities has been a key strategy to restore normal tissue functions. Current approaches involve establishing a favorable cellular redox environment through the administration of therapeutic drugs and redox-active nanomaterials (RANs). In particular, RANs not only provide a stable and reliable means of therapeutic delivery but also possess the capacity to finely tune various interconnected components, including radicals, enzymes, proteins, transcription factors, and metabolites. Here, we discuss the roles that engineered RANs play in a spectrum of pathological conditions, such as cancer, neurodegenerative diseases, infections, and inflammation. We visualize the dual functions of RANs as both generator and scavenger of ROS, emphasizing their profound impact on diverse cellular functions. The focus of this review is solely on inorganic redox-active nanomaterials (inorganic RANs). Additionally, we deliberate on the challenges associated with current RANs-based approaches and propose potential research directions for their future clinical translation.

Reactive oxygen species-scavenging nanomaterials for the prevention and treatment of age-related diseases

With increasing proportion of the elderly in the population, age-related diseases (ARD) lead to a considerable healthcare burden to society. Prevention and treatment of ARD can decrease the negative impact of aging and the burden of disease. The aging rate is closely associated with the production of high levels of reactive oxygen species (ROS). ROS-mediated oxidative stress in aging triggers aging-related changes through lipid peroxidation, protein oxidation, and DNA oxidation. Antioxidants can control autoxidation by scavenging free radicals or inhibiting their formation, thereby reducing oxidative stress. Benefiting from significant advances in nanotechnology, a large number of nanomaterials with ROS-scavenging capabilities have been developed. ROS-scavenging nanomaterials can be divided into two categories: nanomaterials as carriers for delivering ROS-scavenging drugs, and nanomaterials themselves with ROS-scavenging activity. This study summarizes the current advances in ROS-scavenging nanomaterials for prevention and treatment of ARD, highlights the potential mechanisms of the nanomaterials used and discusses the challenges and prospects for their applications.

Cerium oxide nanoparticles improve the post-thaw quality and in-vivo fertility of Beetal buck spermatozoa

The motility, health quality, and membrane disorders of spermatozoa are adversely affected during the process of semen cryopreservation due to the over-production of reactive oxygen species (ROS). Cerium oxide nanoparticles (CeO2NPs) possess properties to scavenge ROS either by mimicking specific antioxidants or by enhancing the activities of antioxidant enzymes. Therefore, we aimed at evaluating the effects of adding the CeO2NPs in the TRIS-citrate-yolk extender on in-vitro antioxidant enzyme activities, spermatozoa quality attributes, and in-vivo fertility of post-thaw Beetal buck spermatozoa. The CeO2NPs were prepared and characterized (UV-spectrophotometry, FTIR, and XRD). Semen samples, collected from bucks (n = 5), were distributed into five aliquots and diluted in an extender containing increasing concentrations of nanoparticles (0 μg/ml, called the control group, 25 μg/mL, 50 μg/mL, 75 μg/mL, and 100 μg/mL). At post-thaw, spermatozoa were evaluated for the above-mentioned attributes and the pregnancy rate by inseminating Beetal does (n = 252). Results demonstrated that CeO2NPs mitigated the detrimental effects of cryopreservation as ROS production and lipid peroxidation were lower (P < 0.001) in the 25, 50, and 75 μg/mL CeO2NPs-added groups compared to the control and 100 μg/ml CeO2NPs-added group. The addition of 25 μg/mL CeO2NPs improved (P < 0.001) the activities of superoxide dismutase, catalase, and peroxidase and the concentration of reduced glutathione (P < 0.001) compared to the other groups. In terms of sperm kinematics and velocity parameters, the groups added with the 25 and 50 μg/mL CeO2NPs exhibited higher total motility (P < 0.001), sperm progressive motility (P = 0.003), and rapid velocity (P < 0.001). The group added with the 50 μg/mL CeO2NPs had the highest (P = 0.04) average path velocity. The groups added with the 25 and 50 μg/mL CeO2NPs also exhibited higher plasma membrane integrity (P = 0.003), acrosomal integrity, and viability (P < 0.001) compared to the control group. The DNA integrity was also higher (P < 0.001) in all the CeO2NPs-added groups. The pregnancy rate was higher (P = 0.003) in the 25 (51.92 %) and 50 μg/mL CeO2NPs (58.33 %) groups compared to the other groups. Conclusively, our findings suggest that the inclusion of cerium oxide nanoparticles in the TRIS-citrate-yolk freezing extender can reduce the occurrence of cryopreservation-induced damages to Beetal's buck spermatozoa and ultimately enhance the pregnancy rate in does.

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.

A Detailed Insight into the Effects of Morphologies of Cerium Oxide on Fenton-like Reactions for Different Applications

As an exceptional Fenton-like reagent, cerium oxide (CeO2 ) finds applications in biomedical science and organic pollutants treatment. The Fenton-like reaction catalyzed by CeO2 typically encompasses two distinct processes: one resembling the classical Fenton reaction, wherein cerium (Ce3+ ) triggers the decomposition of hydrogen peroxide (H2 O2 ) to yield reactive oxygen species (ROS), and the other involves the complexation of H2 O2 on the Ce3+ surface, leading to the formation of peroxides. However, the influence of diverse CeO2 morphologies on these two reaction pathways has not been comprehensively explored. In this study, CeO2 exhibiting three typical morphologies, rods, cubes, and spheres, were prepared. The generation of ROS and peroxides was evaluated using the 3,3,5,5-tetramethylbenzidine (TMB) oxidation reaction and the reduction current of H2 O2 , respectively. Moreover, the impacts of pH variations and CeO2 /H2 O2 concentrations on the production and conversion of these two reaction products were investigated. To corroborate the distinctions between the resultant products and their applicability, apoptosis assays and acid orange 7 (AO7) degradation analyses were performed. Notably, CeO2 rods exhibited the highest proportion of Ce3+ , predominantly engaging in complexation with H2 O2 to foster peroxide formation, thereby facilitating the robust degradation of AO7. However, the generated peroxides appeared to occupy Ce3+ sites, thereby impeding the H2 O2 decomposition process. Conversely, Ce3+ species on the surface of CeO2 cubes were primarily involved in H2 O2 decomposition, leading to heightened ROS production, and thus showcasing substantial potential for damaging A549 tumor cells. It is worth noting that the ability of these Ce3+ species to form peroxides through complexation with H2 O2 was comparatively reduced. In summation, this study sheds light on the intricate interplay between distinct CeO2 morphologies and their divergent impacts on Fenton-like reactions. These findings expand our comprehension of the influences on its reactivity of CeO2 morphologies and open new insights for applications in diverse domains, from organic dye degradation to tumor therapy.

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.

The Impressive Anti-Inflammatory Activity of Cerium Oxide Nanoparticles: More than Redox?

Cerium oxide nanoparticles (CNPs) are biocompatible nanozymes exerting multifunctional biomimetic activities, including superoxide dismutase (SOD), catalase, glutathione peroxidase, photolyase, and phosphatase. SOD- and catalase-mimesis depend on Ce3+/Ce4+ redox switch on nanoparticle surface, which allows scavenging the most noxious reactive oxygen species in a self-regenerating, energy-free manner. As oxidative stress plays pivotal roles in the pathogenesis of inflammatory disorders, CNPs have recently attracted attention as potential anti-inflammatory agents. A careful survey of the literature reveals that CNPs, alone or as constituents of implants and scaffolds, strongly contrast chronic inflammation (including neurodegenerative and autoimmune diseases, liver steatosis, gastrointestinal disorders), infections, and trauma, thereby ameliorating/restoring organ function. By general consensus, CNPs inhibit inflammation cues while boosting the pro-resolving anti-inflammatory signaling pathways. The mechanism of CNPs' anti-inflammatory effects has hardly been investigated, being rather deductively attributed to CNP-induced ROS scavenging. However, CNPs are multi-functional nanozymes that exert additional bioactivities independent from the Ce3+/Ce4+ redox switch, such as phosphatase activity, which could conceivably mediate some of the anti-inflammatory effects reported, suggesting that CNPs fight inflammation via pleiotropic actions. Since CNP anti-inflammatory activity is potentially a pharmacological breakthrough, it is important to precisely attribute the described effects to one or another of their nanozyme functions, thus achieving therapeutic credibility.

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".

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.

Targeting Endogenous Reactive Oxygen Species Removal and Regulating Regenerative Microenvironment at Annulus Fibrosus Defects Promote Tissue Repair

The excessive reactive oxygen species (ROS) level, inflammation, and weak tissue regeneration ability after annulus fibrosus (AF) injury constitute an unfavorable microenvironment for AF repair. AF integrity is crucial for preventing disc herniation after discectomy; however, there is no effective way to repair the AF. Herein, a composite hydrogel integrating properties of antioxidant, anti-inflammation, and recruitment of AF cells is developed through adding mesoporous silica nanoparticles modified by ceria and transforming growth factor β3 (TGF-β3) to the hydrogels. The nanoparticle loaded gelatin methacrylate/hyaluronic acid methacrylate composite hydrogels eliminate ROS and induce anti-inflammatory M2 type macrophage polarization. The released TGF-β3 not only plays a role in recruiting AF cells but is also responsible for promoting extracellular matrix secretion. The composite hydrogels can be solidified in situ in the defect area to effectively repair AF in rats. The strategies targeting endogenous ROS removal and improving the regenerative microenvironment by the nanoparticle-loaded composite hydrogels have potential applications in AF repair and intervertebral disc herniation prevention.

Fabrication of a New Hyaluronic Acid/Gelatin Nanocomposite Hydrogel Coating on Titanium-Based Implants for Treating Biofilm Infection and Excessive Inflammatory Response

Persistent inflammation caused by implant-associated biofilm infections has emerged as a significant clinical issue. While many methods have been developed to give implants great anti-biofilm benefits, the post-inflammatory microenvironment is frequently disregarded. Oxidative stress (OS) due to excessive reactive oxygen species (ROS) is considered to be one of the specific physiological signals of the inflammation microenvironment. Herein, ZIF-90-Bi-CeO₂ nanoparticles (NPs) were incorporated into a Schiff-base chemically crosslinked hydrogel composed of aldehyde-based hyaluronic acid and gelatin. Through chemical crosslinking between polydopamine and gelatin, the hydrogel coating adhered to the Ti substrate. The modified Ti substrate gained multimodal antibacterial and anti-biofilm functions, which were attributed to the photothermal effect of Bi NPs, and the release of Zn ions and CeO₂ NPs. Notably, CeO₂ NPs endowed the system with dual-enzyme (SOD- and CAT-like) catalytic activities. In a rat implant-associated infection (IAI) model, the dual-functional hydrogel had a biofilm-removal ability and regulated OS and inflammatory responses to facilitate osseointegration. The photothermal therapy combined with a host inflammation-microenvironment regulation strategy might provide a novel treatment for biofilm infection and the accompanying excessive inflammation.

Synthesis of cubosomes containing cerium oxide nanoparticles from Lactobacillus acidophilus loaded with glatiramer acetate and carboxymethylcellulose coating

Cerium oxide nanoparticles (nano-series) are used as catalysts in industrial applications due to their free radical scavenging properties. Given that free radicals play an essential role in the pathology of many neurological diseases, we investigated the use of nanocrystals as a potential therapeutic agent for oxidative damage. This project synthesized nano-series from a new and environmentally friendly bio-pathway. Investigation of cerium nitrate in culture medium containing inoculated Lactobacillus acidophilus strain before incubation produces nano-series. Loaded with glatiramer acetate (GA) was formed by coating carboxymethylcellulose (CMC) and CeO₂. FE-SEM analysis showed nano-series in the 9-11 nm range, spherical shape, and uniform particle size distribution. Cubic nanoparticles containing anti-multiple sclerosis (anti-Ms) treatment called GA were used. Glycerol monostearate (GMS) was used as a fat base, and evening primrose extract was used as an anti-inflammatory in cubosomes. Design-Expert® software was used to study the effects of different formulation factors on the properties of GA-loaded cubic dispersions. Thirty GA-labeled cubic dispersions were prepared with GA-labeled carboxymethylcellulose and evaluated in vitro. The results showed an average nano-series size of 89.02 and a zeta potential of -49.9. Cubosomes containing GA-CMC/CeO₂ showed a stable release profile for 180 min. The results showed that cubosomes containing GA-CMC/CeO₂ could be a promising drug carrier with normal release behavior.

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.

Nanomaterials alleviating redox stress in neurological diseases: mechanisms and applications

Overproduced reactive oxygen and reactive nitrogen species (RONS) in the brain are involved in the pathogenesis of several neurological diseases, such as Alzheimer's disease, Parkinson's disease, traumatic brain injury, and stroke, as they attack neurons and glial cells, triggering cellular redox stress. Neutralizing RONS, and, thus, alleviating redox stress, can slow down or stop the progression of neurological diseases. Currently, an increasing number of studies are applying nanomaterials (NMs) with anti-redox activity and exploring the potential mechanisms involved in redox stress-related neurological diseases. In this review, we summarize the anti-redox mechanisms of NMs, including mimicking natural oxidoreductase activity and inhibiting RONS generation at the source. In addition, we propose several strategies to enhance the anti-redox ability of NMs and highlight the challenges that need to be resolved in their application. In-depth knowledge of the mechanisms and potential application of NMs in alleviating redox stress will help in the exploration of the therapeutic potential of anti-redox stress NMs in neurological 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.

Nanotechnology Tools Enabling Biological Discovery

Over the years, the engineering aspect of nanotechnology has been significantly exploited. Medical intervention strategies have been developed by leveraging existing molecular biology knowledge and combining it with nanotechnology tools to improve outcomes. However, little attention has been paid to harnessing the strengths of nanotechnology as a biological discovery tool. Fundamental understanding of controlling dynamic biological processes at the subcellular level is key to developing personalized therapeutic and diagnostic interventions. Single-cell analyses using intravital microscopy, expansion microscopy, and microfluidic-based platforms have been helping to better understand cell heterogeneity in healthy and diseased cells, a major challenge in oncology. Also, single-cell analysis has revealed critical signaling pathways and biological intracellular components with key biological functions. The physical manipulation enabled by nanotools can allow real-time monitoring of biological changes at a single-cell level by sampling intracellular fluid from the same cell. The formation of intercellular highways by nanotube-like structures has important clinical implications such as metastasis development. The integration of nanomaterials into optical and molecular imaging techniques has rendered valuable morphological, structural, and biological information. Nanoscale imaging unravels mechanisms of temporality by enabling the visualization of nanoscale dynamics never observed or measured between individual cells with standard biological techniques. The exceptional sensitivity of nanozymes, artificial enzymes, make them perfect components of the next-generation mobile diagnostics devices. Here, we highlight these impactful cancer-related biological discoveries enabled by nanotechnology and producing a paradigm shift in cancer research and oncology.

The Antioxidant Effect of the Metal and Metal-Oxide Nanoparticles

Inorganic nanoparticles, such as CeO₃, TiO₂ and Fe₃O₄ could be served as a platform for their excellent performance in antioxidant effect. They may offer the feasibility to be further developed for their smaller and controllable sizes, flexibility to be modified, relative low toxicity as well as ease of preparation. In this work, the recent progress of these nanoparticles were illustrated, and the antioxidant mechanism of the inorganic nanoparticles were introduced, which mainly included antioxidant enzyme-mimetic activity and antioxidant ROS/RNS scavenging activity. The antioxidant effects and the applications of several nanoparticles, such as CeO₃, Fe₃O₄, TiO₂ and Se, are summarized in this paper. The potential toxicity of these nanoparticles both in vitro and in vivo was well studied for the further applications. Future directions of how to utilize these inorganic nanoparticles to be further applied in some fields, such as medicine, cosmetic and functional food additives were also investigated in this paper.

Risk Analysis and Technology Assessment of Emerging (Gd,Ce)2O2S Multifunctional Nanoparticles: An Attempt for Early Safer-by-Design Approach

Acceptability and relevance of nanoparticles in the society is greatly improved using a safer-by-design strategy. However, this is difficult to implement when too late in the development process or when nanoparticles are already on the market (e.g., TiO2). We employ this strategy for emerging nanoparticles of lanthanide oxysulfide of formula (Gd,Ce)2O2S, relevant for photocatalysis as well as for multimodal imaging, as the bandgap of the nanoparticles, related to their Ce content, impacts their ability to absorb visible light. As a first step, we investigated the production of reactive oxygen species (ROS) as a function of cerium content, in abiotic conditions and in vitro using murine macrophage RAW 264.7 cell line. We demonstrate that, at sub-lethal doses, Ce-containing oxysulfide nanoparticles are responsible for a higher ROS intracellular formation than cerium-free Gd2O2S nanoparticles, although no significant inflammatory response or oxidative stress was measured. Moreover, there was no significant loss of cerium as free cation from the nanoparticles, as evidenced by X-ray fluorescence mapping. Based on these results, we propose a risk analysis for lanthanide oxysulfide nanoparticles, leading to a technology assessment that fulfills the safer-by-design strategy.

Redox Active Cerium Oxide Nanoparticles: Current Status and Burning Issues

Research on cerium oxide nanoparticles (nanoceria) has captivated the scientific community due to their unique physical and chemical properties, such as redox activity and oxygen buffering capacity, which made them available for many technical applications, including biomedical applications. The redox mimetic antioxidant properties of nanoceria have been effective in the treatment of many diseases caused by reactive oxygen species (ROS) and reactive nitrogen species. The mechanism of ROS scavenging activity of nanoceria is still elusive, and its redox activity is controversial due to mixed reports in the literature showing pro-oxidant and antioxidant activity. In light of its current research interest, it is critical to understand the behavior of nanoceria in the biological environment and provide answers to some of the critical and open issues. This review critically analyzes the status of research on the application of nanoceria to treat diseases caused by ROS. It reviews the proposed mechanism of action and shows the effect of surface coatings on its redox activity. It also discusses some of the crucial issues in deciphering the mechanism and redox activity of nanoceria and suggests areas of future research.

Role of cerium oxide nanoparticles in improving oxidative stress and developmental delays in Drosophila melanogaster as an in-vivo model for bisphenol a toxicity

Bisphenol A (BPA) is an endocrine-disrupting chemical used commonly in the manufacture of plastic bottles, beverage cans, consumer products, and medical devices. It has a high risk of disrupting hormone-mediated processes which are critical for the growth and development of an infant. In the present study, the flies are exposed to different concentrations of BPA (0.05 and 0.5 mM), which represented the federally regulated LOAEL (50 mg/kg bw/day) and a higher dose of 1 mM, to study the change in cell death, nuclear instability oxidative stress, and behavioral anomalies leading to complex behavioral disorders like Autism. Effects of BPA doses (0.05, 0.5, 1 mM) were studied and the flies showed deficits in social interaction, locomotion, and enhanced oxidative stress that was found to be deteriorating among the flies. Automated tracking and robust MATLAB analysis of behavioral paradigms like position, movement, velocity, and courtship have given us an insight into a detrimental change in development and behavior when exposed to BPA. The flies were also co-treated with Cerium Oxide nanoparticles (CeO₂ NP), well known for its antioxidant properties due to their antioxidant enzyme biomimetic nature, resulted in low oxidative stress, genotoxicity, and an improvement in behavior. In this work, we have tested our hypothesis of oxidative stress and nuclear instability as a potent cause for improper development in Drosophila when exposed to EDCs like BPA which is a potential hazard for both health and environment and might lead to various developmental disorders in children.

Cerium-Containing N-Acetyl-6-Aminohexanoic Acid Formulation Accelerates Wound Reparation in Diabetic Animals

Background: The main goal of our study was to explore the wound-healing property of a novel cerium-containing N-acethyl-6-aminohexanoate acid compound and determine key molecular targets of the compound mode of action in diabetic animals. Methods: Cerium N-acetyl-6-aminohexanoate (laboratory name LHT-8-17) as a 10 mg/mL aquatic spray was used as wound experimental topical therapy. LHT-8-17 toxicity was assessed in human skin epidermal cell culture using (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. A linear wound was reproduced in 18 outbred white rats with streptozotocin-induced (60 mg/kg i.p.) diabetes; planar cutaneous defect was modelled in 60 C57Bl₆ mice with streptozotocin-induced (200 mg/kg i.p.) diabetes and 90 diabetic db/db mice. Firmness of the forming scar was assessed mechanically. Skin defect covering was histologically evaluated on days 5, 10, 15, and 20. Tissue TNF-α, IL-1β and IL-10 levels were determined by quantitative ELISA. Oxidative stress activity was detected by Fe-induced chemiluminescence. Ki-67 expression and CD34 cell positivity were assessed using immunohistochemistry. FGFR3 gene expression was detected by real-time PCR. LHT-8-17 anti-microbial potency was assessed in wound tissues contaminated by MRSA. Results: LHT-8-17 4 mg twice daily accelerated linear and planar wound healing in animals with type 1 and type 2 diabetes. The formulated topical application depressed tissue TNF-α, IL-1β, and oxidative reaction activity along with sustaining both the IL-10 concentration and antioxidant capacity. LHT-8-17 induced Ki-67 positivity of fibroblasts and pro-keratinocytes, upregulated FGFR3 gene expression, and increased tissue vascularization. The formulation possessed anti-microbial properties. Conclusions: The obtained results allow us to consider the formulation as a promising pharmacological agent for diabetic wound topical treatment.

Ameliorative Role of Cerium Oxide Nanoparticles Against Fipronil Impact on Brain Function, Oxidative Stress, and Apoptotic Cascades in Albino Rats

Fipronil (FIP) is an N-phenylpyrazole insecticide that is used extensively in public health and agriculture against a wide range of pests. Exposure to FIP is linked to negative health outcomes in humans and animals including promoting neuronal cell injury, which results in apoptosis through the production of reactive oxygen species (ROS). Therefore, the purpose of the current study was to investigate the neuroprotective effects of cerium oxide nanoparticles (CeNPs) on neuronal dysfunction induced by FIP in albino rats. Male rats were randomly classified into four groups: control, FIP (5 mg/kg bwt), CeNPs (35 mg/kg bwt), and FIP + CeNPs (5 (FIP) + 35 (CeNPs) mg/kg bwt), which were treated orally once daily for 28 consecutive days. Brain antioxidant parameters, histopathology, and mRNA expression of genes related to brain function were evaluated. The results revealed oxidative damage to brain tissues in FIP-treated rats indicated by the elevated levels of malondialdehyde (MDA) and nitric oxide (NO) levels and reduced activities of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx). On the other hand, the FIP’s group that was treated with CeNPs showed decrease in MDA and NO levels and increase in SOD and GPx enzymes activity. Besides, FIP-treated rats showed decreased butyrylcholinesterase (BuChE) activity in comparison to the FIP + CeNPs group. Moreover, FIP caused up-regulation of the expression of neuron-specific enolase (NSE), caspase-3, and glial fibrillary acidic protein (GFAP) but down-regulation of B-cell lymphoma-2 (BCL-2) expression. But the FIP + CeNPs group significantly down-regulated the GFAP, NSE, and caspase-3 and up-regulated the gene expression of BCL-2. Additionally, the FIP-treated group of rats had clear degenerative lesions in brain tissue that was reversed to nearly normal cerebral architecture by the FIP + CeNPs treatment. Immunohistochemical examination of brain tissues of rats-treated with FIP showed abundant ionized calcium-binding adaptor molecule 1 (Iba-1) microglia and caspase-3 and apoptotic cells with nearly negative calbindin and synaptophysin reaction, which were countered by FIP + CeNPs treatment that revealed a critical decrease in caspase-3, Iba-1 reaction with a strong calbindin positive reaction in most of the Purkinje cells and strong synaptophysin reaction in the cerebrum and cerebellum tissues. Based on reported results herein, CeNPs treatment might counteract the neurotoxic effect of FIP pesticide via an antioxidant-mediated mechanism.

Polyoxometalate-Mediated Vacancy-Engineered Cerium Oxide Nanoparticles Exhibiting Controlled Biological Enzyme-Mimicking Activities

The biological enzyme-mimetic activity of cerium oxide nanoparticles (CeNPs) is well known to scavenge the reactive oxygen and nitrogen species in cell culture and animal models, imparting protection from the deleterious effects of oxidative and nitrosative stress. The superoxide dismutase (SOD)- and catalase-mimicking activity of CeNPs is reported to be controlled by the oxidation state of the surface "Ce" ions, where a high ratio of Ce^3+/4+ or Ce^4+/3+ has been considered for the displayed SOD and catalase-like activity, respectively. However, the redox behavior of CeNPs can be controlled by certain ligands that could offer changes in their enzyme-mimetic properties. Therefore, in this work, we have studied the enzyme-mimetic activities of CeNPs under the influence of polyoxometalates [phosphomolybdic acid (PMA) and phosphotungstic acid (PTA)], which are electron-dense molecules displaying quick and reversible multielectron redox reactions. Results revealed that the interaction of PMA with CeNPs results in the inhibition of the SOD-like activity; however, it has no impact on the catalase-like activity. Contrary to this, the interaction of PTA with CeNPs improved the SOD as well as catalase-like activities of CeNPs (3+), which generally do not exhibit catalase activity in the bare form. Although CeNPs (3+) did not show any peroxidase-like activity, CeNPs (4+) showed excellent activity, which was enhanced after the interaction with polyoxometalates. Further, the autoregeneration ability of CeNPs was found to be intact even after PTA or PMA interaction; however, the full catalytic activity was observed in the case of PTA but partially with PMA.

Toxicological assessment of CeO2 nanoparticles on early development of zebrafish

Nanomaterials involve an active research and a booming area including different fields (health, environment, electronics, manufacturing, drug delivery). Recently, new concerns are emerging about the risk from increased production and subsequent release into the environment, as they are largely present in consumer products and industrial applications. Our aim was to assess the effects of three different types of cerium oxide nanoparticles (CeO2 NPs) (type 1 defined "as prepared"; type 2 defined "modified"; type 3 defined "commercial") on zebrafish embryos by Fish Embryo Toxicity test (Z-FET). Immunohistochemical analysis was also performed on treated larvae to evaluate the expression of the following biomarkers: Metallothionein, Heat Shock Protein 70 (HSP70) and 7-Ethoxyresorufin-O-Dietylase (EROD). After 96 h of exposure, there was no lethality, nor were there sub-lethal effects in embryonic development, when compared with the control. No particular positivity was found about Metallothionein and HSP70 expression, while an increased expression of EROD was observed in larvae exposed to the three types of CeO2 NPs compared with the controls. The analyze has confirmed a statistically significant difference (P < 0.001) to EROD biomarker between control group and treated larvae response, finding was higher at 1-mg/l concentration. Further investigations in order to solve conflicting views about potential effects of CeO2 NPs are necessary, also to evaluate its effectiveness in different fields as already reported in literature.

The Role of Nanomaterials in Stroke Treatment: Targeting Oxidative Stress

Stroke has a high rate of morbidity and disability, which seriously endangers human health. In stroke, oxidative stress leads to further damage to the brain tissue. Therefore, treatment for oxidative stress is urgently needed. However, antioxidative drugs have demonstrated obvious protective effects in preclinical studies, but the clinical studies have not seen breakthroughs. Nanomaterials, with their characteristically small size, can be used to deliver drugs and have demonstrated excellent performance in treating various diseases. Additionally, some nanomaterials have shown potential in scavenging reactive oxygen species (ROS) in stroke according to the nature of nanomaterials. The drugs' delivery ability of nanomaterials has great significance for the clinical translation and application of antioxidants. It increases drug blood concentration and half-life and targets the ischemic brain to protect cells from oxidative stress-induced death. This review summarizes the characteristics and progress of nanomaterials in the application of antioxidant therapy in stroke, including ischemic stroke, hemorrhagic stroke, and neural regeneration. We also discuss the prospect of nanomaterials for the treatment of oxidative stress in stroke and the challenges in their application, such as the toxicity and the off-target effects of nanomaterials.

The potential ameliorative impacts of cerium oxide nanoparticles against fipronil-induced hepatic steatosis

Fipronil (FIP) is a phenylpyrazole insecticide that is commonly used in agricultural and veterinary fields for controlling a wide range of insects, but it is a strong environmentally toxic substance. Exposure to FIP has been reported to increase the hepatic fat accumulation through altered lipid metabolism, which ultimately can contribute to nonalcoholic fatty liver disease (NAFLD) development. The present study aimed to examine the function of cerium oxide nanoparticles (CeNPs) in protecting against hepatotoxicity and lipogenesis induced by FIP. Twenty-eight male albino rats were classified into four groups: FIP (5 mg/kg/day per os), CTR, CeNPs (35 mg/kg/day p.o.), and FIP + CeNPs (5 (FIP) + 35 (CeNPs) mg/kg/day p.o.) for 28 consecutive days. Serum lipid profiles, hepatic antioxidant parameters and pathology, and mRNA expression of adipocytokines were assessed. The results revealed that FIP increased cholesterol, height-density lipoprotein, triacylglyceride, low-density lipoprotein (LDL-c), and very-low-density lipoprotein (VLDL-c) concentrations. It also increased nitric oxide (NO) and malondialdehyde (MDA) hepatic levels and reduced glutathione peroxidase (GPx) and superoxide dismutase (SOD) enzyme activities. Additionally, FIP up-regulated the fatty acid-binding protein (FABP), acetyl Co-A carboxylase (ACC1), and peroxisome proliferator-activated receptor-alpha (PPAR-α). Immunohistochemically, a strong proliferation of cell nuclear antigen (PCNA), ionized calcium-binding adapter molecule 1 (Iba-1), cyclooxygenase-2 (COX-2) reactions in the endothelial cells of the hepatic sinusoids, and increased expression of caspase3 were observed following FIP intoxication. FIP also caused histological changes in hepatic tissue. The CeNPs counteracted the hepatotoxic effect of FIP exposure. So, this study recorded an ameliorative effect of CeNPs against FIP-induced hepatotoxicity.

Engineered defects in cerium oxides: tuning chemical reactivity for biomedical, environmental, & energy applications

Nanocrystalline cerium oxide (nanoceria) is a rare earth oxide with a complex surface chemistry. This material has seen substantial investigation in recent years in both fundamental and applied studies due largely to more precise characterization of the unique surface structures, which mediate its pronounced redox activity. In particular, oxygen storage/buffering capacities have been thoroughly correlated with synthesis and processing condition effects on other material features such as surface (micro-) faceting, reconstruction, and (extent of) hydration. Key material features such as these modulate nanoceria redox performance by changing the crystal microenvironment. In this review, we present nanoengineering methods, which have produced increased nanoceria performance in biomedical, energy, and catalysis applications. The impact of combined/cooperative theoretical and experimental studies are highlighted throughout.

Variable in Vivo and in Vitro Biological Effects of Cerium Oxide Nanoparticle Formulations

Cerium oxide nanoparticles (CeNPs) exhibit redox capacity in vitro with efficacy in in vivo disease models of oxidative stress. Here we compare, in parallel, three CeNP formulations with distinct chemical stabilizers and size. In vitro assays revealed antioxidant activity from all the CeNPs, but when administered to mice with a reactive oxygen species (ROS) mediated model of multiple sclerosis, only custom-synthesized Cerion NRx (CNRx) citrate-EDTA stabilized CeNPs provided protection against disease. Detectable levels of ceria and reduced ROS levels in the brains of CNRx CeNP-treated mice imply that these CeNPs' unique properties influence tissue distribution and subsequent biological activity, suggesting why differing CeNP formulations yield different in vivo effects in various models. Further, the variation in in vivo vs in vitro results with these CeNP formulations highlights the necessity for in vivo studies that confirm whether the inherent catalytic activity of CeNPs is maintained after transport and distribution within intact biological systems.

Cerium oxide nanoparticles: properties, biosynthesis and biomedical application

Cerium oxide nanoparticles have revolutionized the biomedical field and is still in very fast pace of development. Hence, this work elaborates the physicochemical properties, biosynthesis, and biomedical applications of cerium oxide nanoparticles.

Cerium oxide nanoparticles: A promising tool for the treatment of fibrosarcoma in-vivo

In this study, we used cerium oxide nanoparticles and evaluated their anti-cancer effects in a mouse model of fibrosarcoma. For evaluation of anti-cancer effects of nanoceria, tumor volume measurement, TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, quantitative real-time PCR (qPCR) for Bax and Bcl2 genes, a panel of liver and kidney function tests and hematoxylin-eosin staining were done. Nanoceria dominantly accumulated in the tumor and it could significantly decrease tumor growth and volume in tumor-bearing mice that received nanoceria for four weeks. Cerium oxide nanoparticle showed potential anti-cancer properties against fibrosarcoma.

In Vitro and In Vivo Antioxidant Activity of the New Magnetic-Cerium Oxide Nanoconjugates

BACKGROUND

Cerium oxide nanoparticles present the mimetic activity of superoxide dismutase, being able to inactivate the excess of reactive oxygen species (ROS) correlated with a large number of pathologies, such as stents restenosis and the occurrence of genetic mutations that can cause cancer. This study presents the synthesis and biological characterisation of nanoconjugates based on nanoparticles of iron oxide interconnected with cerium oxide conjugates.

METHODS

The synthesis of magnetite-nanoceria nanoconjugates has been done in several stages, where the key to the process is the coating of nanoparticles with polyethyleneimine and its chemical activation-reticulation with glutaraldehyde. The nanoconjugates are characterised by several techniques, and the antioxidant activity was evaluated in vitro and in vivo.

RESULTS

Iron oxide nanoparticles interconnected with cerium oxide nanoparticles were obtained, having an average diameter of 8 nm. Nanoconjugates prove to possess superparamagnetic properties and the saturation magnetisation varies with the addition of diamagnetic components in the system, remaining within the limits of biomedical applications. In vitro free-radical scavenging properties of nanoceria are improved after the coating of nanoparticles with polyethylenimine and conjugation with magnetite nanoparticles. In vivo studies reveal increased antioxidant activity in all organs and fluids collected from mice, which demonstrates the ability of the nanoconjugates to reduce oxidative stress.

CONCLUSION

Nanoconjugates possess magnetic properties, being able to scavenge free radicals, reducing the oxidative stress. The combination of the two properties mentioned above makes them excellent candidates for theranostic applications.

Superoxide dismutase mimetic nanoceria restrains cerulein induced acute pancreatitis

Aim: The present study was carried out to assess the effect of nanoceria (NC) on pancreatic inflammation caused by cerulein. Methods: NC was characterized and in vitro studies were carried out in murine macrophages. The in vivo effects were tested on cerulein-induced pancreatitis. Results: In vitro treatment with NC remarkably protected macrophages from lipopolysaccharide-induced inflammation and oxidative stress as evident from the results of 2',7'-dichlorofluorescin diacetate, JC-1 and MitoSox staining. In vivo treatment with NC showed potent superoxide dismutase and catalase mimetic activity, antipancreatitis activity and improved histology. Furthermore, it reduced the expression of p65-NF-κB and acetylation of histone H3 at lysine K14, K56 and K79 residues. Conclusion: We for the first time, demonstrate that NC may be a promising candidate for the therapy of pancreatitis.

Antioxidant properties of ALD grown nanoceria films with tunable valency

Herein, we provide the first account of a method to control cerium oxide's mixed valence states (as Ce³⁺ to Ce⁴⁺ ratio) in ultra-thin films formed via atomic layer deposition (ALD). It is determined that modulation of Ce³⁺/Ce⁴⁺ ratio occurs with respect to film thickness and is analogous to the change in surface chemistry observed for cerium oxide nanoparticles with varying particle diameter. The influence of film thickness on enzyme-mimetic radical scavenging is also characterized. Higher film thicknesses show 9-fold increase in catalytic activity. In vitro biocompatibility (apoptosis < 4%) and electrochemical biosensing (lowest concentration: 18 ppt) studies were performed to demonstrate the potential of ALD-grown nanoceria films for biomedical applications.

Antioxidant activity of cerium dioxide nanoparticles and nanorods in scavenging hydroxyl radicals

Cerium oxide nanoparticles (CeNPs) have been shown to exhibit antioxidant capabilities, but their efficiency in scavenging reactive oxygen species (ROS) and the underlying mechanisms are not yet well understood. In this study, cerium dioxide nanoparticles (CeNPs) and nanorods (CeNRs) were found to exhibit much stronger scavenging activity than ·OH generation in phosphate buffered saline (PBS) and surrogate lung fluid (SLF). The larger surface area and higher defect density of CeNRs may lead to higher ·OH scavenging activity than for CeNPs. These insights are important to understand the redox activity of cerium nanomaterials and provide clues to the role of CeNPs in biological and environmental processes.

Engineered nanoceria cytoprotection in vivo: mitigation of reactive oxygen species and double-stranded DNA breakage due to radiation exposure

Cerium oxide nanomaterials are known to absorb ionizing radiation energy, as well as to neutralize free radicals in solution, by undergoing redox changes. We, therefore, proposed that ceria nanoparticles could be used in biomedical applications as an injectable, radio-protectant material. In this study, we examine the effectiveness of engineered nanoparticles in protecting germ cells from the damaging effects of irradiation-induced cell death, in vivo. C57BL/6J male mice were used as a model and irradiation was localized to the scrotal region at 2.5, 5, and/or 10 Gy intensities. Ceria nanoparticles were introduced as 100 μL injections at 100 nM and 100 μM via tail vein injections, weekly, for one month. Following this, the animals were sacrificed and their organs (heart, brain, kidneys) were harvested. Tissues were fixed, sectioned, and stained for instances of cell death, DNA damage (TUNEL assay), and ROS (nitro-tyrosine evolution). Tissues from mice treated with ceria nanoparticles showed significantly less (∼13% decrease; *P < 0.05) tissue damage (per immunohistochemistry) over controls at up to 5 Gy radiation. DNA damage and ROS also decrease substantially with ceria treatment, confirming ceria's capacity as an injectable, radio-protectant material. The study also highlights the ability of ceria nanoparticles to protect cells/tissues from both direct and indirect effects of ionizing radiation.

Nanoparticles in Medicine: A Focus on Vascular Oxidative Stress

Nanotechnology has had a significant impact on medicine in recent years, its application being referred to as nanomedicine. Nanoparticles have certain properties with biomedical applications; however, in some situations, they have demonstrated cell toxicity, which has caused concern surrounding their clinical use. In this review, we focus on two aspects: first, we summarize the types of nanoparticles according to their chemical composition and the general characteristics of their use in medicine, and second, we review the applications of nanoparticles in vascular alteration, especially in endothelial dysfunction related to oxidative stress. This condition can lead to a reduction in nitric oxide (NO) bioavailability, consequently affecting vascular tone regulation and endothelial dysfunction, which is the first phase in the development of cardiovascular diseases. Therefore, nanoparticles with antioxidant properties may improve vascular dysfunction associated with hypertension, diabetes mellitus, or atherosclerosis.

Not Only Redox: The Multifaceted Activity of Cerium Oxide Nanoparticles in Cancer Prevention and Therapy

Much information is accumulating on the effect of cerium oxide nanoparticles (CNPs) as cell-protective agents, reducing oxidative stress through their unique ability of scavenging noxious reactive oxygen species via an energy-free, auto-regenerative redox cycle, where superoxides and peroxides are sequentially reduced exploiting the double valence (Ce³⁺/Ce⁴⁺) on nanoparticle surface. In vitro and in vivo studies consistently report that CNPs are responsible for attenuating and preventing almost any oxidative damage and pathology. Particularly, CNPs were found to exert strong anticancer activities, helping correcting the aberrant homeostasis of cancer microenvironment, normalizing stroma-epithelial communication, contrasting angiogenesis, and strengthening the immune response, leading to reduction of tumor mass in vivo. Since these homeostatic alterations are of an oxidative nature, their relief is generally attributed to CNPs redox activity. Other studies however reported that CNPs exert selective cytotoxic activity against cancer cells and sensitize cancer cells to chemotherapy- and radiotherapy-induced apoptosis: such effects are hardly the result of antioxidant activity, suggesting that CNPs exert such important anticancer effects through additional, non-redox mechanisms. Indeed, using Sm-doped CNPs devoid of redox activity, we could recently demonstrate that the radio-sensitizing effect of CNPs on human keratinocytes is independent from the redox switch. Mechanisms involving particle dissolution with release of toxic Ce⁴⁺ atoms, or differential inhibition of the catalase vs. SOD-mimetic activity with accumulation of H₂O₂ have been proposed, explaining such intriguing findings only partially. Much effort is urgently required to address the unconventional mechanisms of the non-redox bioactivity of CNPs, which may provide unexpected medicinal tools against cancer.

Cerium Oxide Nanoparticles: A Brief Review of Their Synthesis Methods and Biomedical Applications

Cerium oxide nanoparticles (CeNPs) exhibit antioxidant properties both in vitro and in vivo. This is due to the self-regeneration of their surface, which is based on redox-cycling between 3+ and 4+ states for cerium, in response to their immediate environment. Additionally, oxygen vacancies in the lattice structure allow for alternating between CeO₂ and CeO2-x during redox reactions. Research to identify and characterize the biomedical applications of CeNPs has been heavily focused on investigating their use in treating diseases that are characterized by higher levels of reactive oxygen species (ROS). Although the bio-mimetic activities of CeNPs have been extensively studied in vitro, in vivo interactions and associated protein corona formation are not well understood. This review describes: (1) the methods of synthesis for CeNPs, including the recent green synthesis methods that offer enhanced biocompatibility and a need for establishing a reference CeNP material for consistency across studies; (2) their enzyme-mimetic activities, with a focus on their antioxidant activities; and, (3) recent experimental evidence that demonstrates their ROS scavenging abilities and their potential use in personalized medicine.

The enzyme-like catalytic activity of cerium oxide nanoparticles and its dependency on Ce3+ surface area concentration

Cerium oxide nanoparticles are known to catalyze the decomposition of reactive oxygen species such as the superoxide radical and hydrogen peroxide. Herein, we examine the superoxide dismutase (SOD) and catalase (CAT) mimetic catalytic activities of nanoceria and demonstrate the existence of generic behaviors. For particles of sizes 4.5, 7.8, 23 and 28 nm, the SOD and CAT catalytic activities exhibit the characteristic shape of a Langmuir isotherm as a function of cerium concentration. The results show that the catalytic effects are enhanced for smaller particles and for the particles with the largest Ce3+ fraction. The SOD-like activity obtained from the different samples is found to superimpose on a single master curve using the Ce3+ surface area concentration as a new variable, indicating the existence of particle independent redox mechanisms. For the CAT assays, the adsorption of H2O2 molecules at the particle surface modulates the efficacy of the decomposition process and must be taken into account. We design an amperometry-based experiment to evaluate the H2O2 adsorption at nanoceria surfaces, leading to the renormalization of the particle specific area. Depending on the particle type the amount of adsorbed H2O2 molecules varies from 2 to 20 nm-2. The proposed scalings are predictive and allow the determination of the SOD and CAT catalytic properties of cerium oxide solely from physicochemical features.

Protective effect of cerium oxide nanoparticle on sperm quality and oxidative damage in malathion-induced testicular toxicity in rats: An experimental study

BACKGROUND

Malathion is an organophosphorus pesticide that commonly used in many agricultural and non-agricultural processes. Previous studies have reported the effects of melatonin on the reproductive system. Cerium dioxide nanoparticles (CeNPs) due to their antioxidative properties are promising to impact on the development of male infertility.

OBJECTIVE

The aim of this study was to evaluate the effect of CeNPs on oxidative stress and sperm parameters after malathion exposure of male rats.

MATERIALS AND METHODS

36 adult male Wistar rats were divided into 6 groups (n=6/each): Control, CeNPs -treated control (15 and 30 mg/kg/day), malathion (100 mg/ kg/day), and CeNPs -treated malathion groups (15 and 30 mg/ kg/day). At the end of the study (4 wk), the sperm counts, motility, and viability in the testis of rats were measured, also lipid peroxidation, total antioxidant capacity, and total thiol groups in homogenate testis were investigated.

RESULTS

Malathion significantly reduced sperm count, viability, and motility than the control rats (p<0.001). Co-treatment of malathion with CeNPs 30 mg/kg had a protective effect on sperm counts (p=0.03), motility (p=0.01), and viability (p<0.001) compare to malathion group. Also, the results showed that malathion reduced testis total anti-oxidant capacity, the total thiol group, and increased testis malondialdehyde than the control rats (p<0.001). CeNPs 30 mg/kg are increased total antioxidant capacity (p<0.001) and total thiol group (p=0.03) compared to malathion group. CeNPs at both doses (15 and 30 mg/kg) improved malondialdehyde than the malathion group (p<0.001 and p=0.01 respectively).

CONCLUSION

CeNPs 30 mg/kg administered considerably restored testicular changes induced by malathion. The improvement of oxidative stress by CeNPs may be associated with increased sperm counts, motility and viability in the testis.

Nanotherapy and Reactive Oxygen Species (ROS) in Cancer: A Novel Perspective

The incidence of numerous types of cancer has been increasing over recent years, representing the second-most frequent cause of death after cardiovascular diseases. Even though, the number of effective anticancer drugs is increasing as well, a large number of patients suffer from severe side effects (e.g., cardiomyopathies) caused by these drugs. This adversely affects the patients’ well-being and quality of life. On the molecular level, tumor cells that survive treatment modalities can become chemotherapy-resistant. In addition, adverse impacts on normal (healthy, stromal) cells occur concomitantly. Strategies that minimize these negative impacts on normal cells and which at the same time target tumor cells efficiently are needed. Recent studies suggest that redox-based combinational nanotherapies may represent one option in this direction. Here, we discuss recent advances in the application of nanoparticles, alone or in combination with other drugs, as a promising anticancer tool. Such novel strategies could well minimize harmful side effects and improve patients’ health prognoses.