Cerium oxide nanostructures: properties, biomedical applications and surface coatings

Emerging Roles of Nanozyme in Tumor Metabolism Regulation: Mechanisms, Applications, and Future Directions

Nanozymes, nanomaterials with intrinsic enzyme activity, have garnered significant attention in recent years due to their catalytic abilities comparable to natural enzymes, cost-effectiveness, high catalytic activities, and stability against environmental fluctuations. As functional analogs of natural enzymes, nanozymes participate in various critical metabolic processes, including glucose metabolism, lactate metabolism, and the maintenance of redox homeostasis, all of which are essential for normal cellular functions. However, disruptions in these metabolic pathways frequently promote tumorigenesis and progression, making them potential therapeutic targets. While several therapies targeting tumor metabolism are currently in clinical or preclinical stages, their efficacy requires further enhancement. Consequently, nanozymes that target tumor metabolism are regarded as a promising therapeutic strategy. Despite extensive studies investigating the application of nanozymes in tumor metabolism, relevant reviews are relatively scarce. This article first introduces the physicochemical properties and biological behaviors of nanozymes. Subsequently, we analyze the role of nanozymes in tumor metabolism and explore their potential applications in tumor therapy. In conclusion, this review aims to foster innovative research in related fields and advance the development of nanozyme-based strategies for cancer diagnostics and therapeutics.

Iron chelators loaded on myocardiocyte mitochondria-targeted nanozyme system for treating myocardial ischemia-reperfusion injury in mouse models

Ferroptosis plays a critical role in myocardial ischemia-reperfusion injury (MIRI), posing a significant clinical challenge. Nanoenzymes like cerium oxide (CeO2) hold promise for mitigating oxidative damage and inhibiting ferroptosis, but their delivery efficiency and biological activity require optimization. This study aims to develop a targeted nanozyme delivery system for MIRI treatment by integrating CeO2 with mesoporous polydopamine (mPDA) and dexrazoxane (DXZ) to achieve synergistic therapeutic effects. A biomineralization technique was used to synthesize CeO2 nanoparticles (2-3 nm) within mPDA, forming ~ 130 nm composite nanoparticles (Ce@mPDA). Surface modifications with cardiac homing peptide (CHP) and triphenylphosphine (TPP) enabled hierarchical targeting to injured myocardium and mitochondria. DXZ-loaded Ce@mPDA-C/P nanoparticles (D/Ce@mPDA-C/P) were evaluated in vitro and in a MIRI mouse model for their effects on oxidative stress, ferroptosis, apoptosis, inflammation, and cardiac function. D/Ce@mPDA-C/P nanoparticles exhibited robust ROS scavenging, sustained DXZ release, and efficient myocardial and mitochondrial targeting. The D/Ce@mPDA-C/P system significantly reduced oxidative stress, upregulated GPX4 expression, inhibited ferroptosis, and modulated the inflammatory microenvironment. Long-term studies in a MIRI mouse model demonstrated reductions in myocardial fibrosis and improvements in cardiac function, including enhanced fractional shortening and ejection fraction. This hierarchical targeting delivery system effectively combines the antioxidant properties of CeO2 with the iron-chelating effects of DXZ, providing a promising therapeutic strategy for MIRI. This approach may expand the clinical use of DXZ and advance nanomedicine-based interventions for myocardial repair.

Potential Applications of Rare Earth Metal Nanoparticles in Biomedicine

In recent years, the world scientific community has shown increasing interest in rare earth metals in general and their nanoparticles in particular. Medicine and pharmaceuticals are no exception in this matter. In this review, we have considered the main opportunities and potential applications of rare earth metal (gadolinium, europium, ytterbium, holmium, lutetium, dysprosium, erbium, terbium, thulium, scandium, yttrium, lanthanum, europium, neodymium, promethium, samarium, praseodymium, cerium) nanoparticles in biomedicine, with data ranging from single reports of effects found in vitro to numerous independent in vivo studies, as well as a number of challenges to their potential for wider application. The main areas of application of rare earth metals, including in the future, are diagnosis and treatment of malignant neoplasms, therapy of infections, as well as the use of antioxidant and regenerative properties of a number of nanoparticles. These applications are determined both by the properties of rare earth metal nanoparticles themselves and the need to search for new approaches to solve a number of urgent biomedical and public health problems. Oxide forms of lanthanides are most often used in biomedicine due to their greatest biocompatibility and nanoscale size, providing penetration through biological membranes. However, the existing contradictory or insufficient data on acute and chronic toxicity of lanthanides still make their widespread use difficult. There are various modification methods (addition of excipients, creation of nanocomposites, and changing the morphology of particles) that can reduce these effects. At the same time, despite the use of some representatives of lanthanides in clinical practice, further studies to establish the full range of pharmacological and toxic effects, as well as the search for approaches to modify nanoparticles remain relevant.

Exploring the Antioxidant Mechanisms of Nanoceria in Protecting HT22 Cells from Oxidative Stress

An excess of reactive oxygen species (ROS), leading to oxidative stress, is a major factor in aging. Antioxidant therapies are considered crucial for delaying aging. Nanoceria, a nanozyme with antioxidant activity, holds significant potential in protecting cells from oxidative stress-induced damage. This research examines the neuroprotective role of nanoceria on HT22 cells subjected to oxidative stress induced by hydrogen peroxide (H2O2) and explores the associated molecular mechanisms. Our findings indicate that nanoceria enhances bcl-2 expression and significantly reduces Bax expression, resulting in an increased bcl-2/Bax ratio, which confirms its anti-apoptotic effect. Nanoceria boosts catalase expression and suppresses the p38 MAPK signaling pathway, indicating its role in shielding HT22 cells from oxidative stress damage induced by H2O2 through various protective mechanisms. These findings provide crucial experimental evidence for the potential applications of nanoceria in skin anti-aging and the prevention and treatment of other oxidative stress-related diseases.

The regulatory mechanisms of cerium oxide nanoparticles in oxidative stress and emerging applications in refractory wound care

Cerium oxide nanoparticles (CeNPs) have emerged as a potent therapeutic agent in the realm of wound healing, attributing their efficacy predominantly to their exceptional antioxidant properties. Mimicking the activity of endogenous antioxidant enzymes, CeNPs alleviate oxidative stress and curtail the generation of inflammatory mediators, thus expediting the wound healing process. Their application spans various disease models, showcasing therapeutic potential in treating inflammatory responses and infections, particularly in oxidative stress-induced chronic wounds such as diabetic ulcers, radiation-induced skin injuries, and psoriasis. Despite the promising advancements in laboratory studies, the clinical translation of CeNPs is challenged by several factors, including biocompatibility, toxicity, effective drug delivery, and the development of multifunctional compounds. Addressing these challenges necessitates advancements in CeNP synthesis and functionalization, novel nano delivery systems, and comprehensive bio effectiveness and safety evaluations. This paper reviews the progress of CeNPs in wound healing, highlighting their mechanisms, applications, challenges, and future perspectives in clinical therapeutics.

Synthesis and characterization of polysiphonia/cerium oxide/nickel oxide nanocomposites for the removal of toxins from contaminated water and antibacterial potential

Due to massive industrial development, organic and inorganic wastes are very common in most industrial effluents from the pharmaceutical industry. Even in low concentrations, they are very dangerous and harmful to humans and other living organisms. Antibiotics are frequently detected in surface waters, in soil, in wastewater from sewage treatment plants, and even in drinking water. The major environmental threat they pose has prompted to search for effective and environmentally friendly means of eliminating these toxins. The biogenic synthesis of nanomaterials using natural herbal extracts has attracted considerable attention due to their low-cost, environmentally friendly and non-toxic nature, and as a reversal of various physical and chemical processes. The ceria nanoparticles (CeO2 NPs), nickel oxide nanoparticles (NiO NPs), and CeO2/NiO nanocomposites (CeO2/NiO NCS) were successfully prepared by simple biosynthetic routes using Polysiphonia urceolata algae extract as green surfactants and tested for toxic ofloxacin removal efficiency. The formed nanostructures were identified and characterized by various microscopic (FESEM-EDX, TEM, XRD, BET, and XPS) and spectroscopic (UV-Vis, FTIR, and TGA) methods. The adsorption/desorption of ofloxacin (OFX) on the surface of the nanomaterials was investigated under optimized conditions (initial dose 20 mg/L, agitation speed 250 rpm, pH 12, adsorbent dose 0.5 mg/L, and contact time 120 min). The removal efficiencies were 78%, 86%, and 94% for CeO2 NPs, NiO NPs and CeO2/NiO NCS, respectively, where OFX removal was found to be spontaneous, followed by Freundlich isotherm and pseudo-second order kinetic reaction model. The OFX adsorption mechanism on the nanomaterials involved the surface complexation via specific electrostatic attraction and H-bonding. The biogenic nanomaterials were also tested for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis and Staphylococcus aureus. The CeO2/NiO NCS exhibited the highest antibacterial activity with zone of inhibition (31.12 ± 0.59 mm) against S. epidermidis, followed by CeO2NPs and NiONPs with zones of inhibition (25.53 ± 1.2 mm) and (21.42 ± 0.6 mm) against P. aeruginosa and S. epidermidis, respectively. This study demonstrated the efficiency of the synthesized nanomaterials in removing toxins such as OFX from contaminated water and can serve as potential antibacterial and antioxidant agents. Notably, the heterogeneous nanomaterials demonstrated remarkable stability across a broad pH range, promising reusability and indicated tremendous potential of waste biomass reduction and OFX effluent treatment.

Polydopamine on Copper-Doped Cerium Dioxide Nanosheets as Peroxidase Mimics for the Intelligent Detection of Cholesterol

The catalytic ability of nanozymes has become an enzymology hotspot in the field of application. Most nanozymes were characterized to simultaneously have oxidase-like and peroxidase-like activities, but the practical application often focuses on certain activity; other complex activities may cause interference. The peroxidase-like activity (POD-like activity) of nanozymes have been widely used in the colorimetric detection of H2O2 or substances producing H2O2 as an intermediate, such as the detection of small biological molecules with the oxidative reaction of a chromogenic reagent in the presence of POD-like nanozymes. In this work, we used polydopamine (PDA) as the surface coating of Cu-CeO2 nanosheets (PDA@ Cu-CeO2), which enhanced peroxidase-like activity while inhibiting their oxidase-like activity, providing a feasible method for the sensitive determination of cholesterol by integrating visual colorimetric detection and a smartphone application as a readout. The absorbance intensity and RGB values displayed a linear range on cholesterol from 0.05 to 1.2 mM with the LOD (limit of detection) of 42.7 and 99.4 μM. In addition, the method is expected to apply in detecting cholesterol in human serum with acceptable accuracy.

Nano transdermal system combining mitochondria-targeting cerium oxide nanoparticles with all-trans retinoic acid for psoriasis

Psoriasis is an inflammatory skin disease that is intricately linked to oxidative stress. Antioxidation and inhibition of abnormal proliferation of keratinocytes are pivotal strategies for psoriasis. Delivering drugs with these effects to the site of skin lesions is a challenge that needs to be solved. Herein, we reported a nanotransdermal delivery system composed of all-trans retinoic acid (TRA), triphenylphosphine (TPP)-modified cerium oxide (CeO2) nanoparticles, flexible nanoliposomes and gels (TCeO2-TRA-FNL-Gel). The results revealed that TCeO2 synthesized by the anti-micelle method, with a size of approximately 5 nm, possessed excellent mitochondrial targeting ability and valence conversion capability related to scavenging reactive oxygen species (ROS). TCeO2-TRA-FNL prepared by the film dispersion method, with a size of approximately 70 nm, showed high drug encapsulation efficiency (>96%). TCeO2-TRA-FNL-Gel further showed sustained drug release behaviors, great transdermal permeation ability, and greater skin retention than the free TRA. The results of in vitro EGF-induced and H2O2-induced models suggested that TCeO2-TRA-FNL effectively reduced the level of inflammation and alleviated oxidative stress in HaCat cells. The results of in vivo imiquimod (IMQ)-induced model indicated that TCeO2-TRA-FNL-Gel could greatly alleviate the psoriasis symptoms. In summary, the transdermal drug delivery system designed in this study has shown excellent therapeutic effects on psoriasis and is prospective for the safe and accurate therapy of psoriasis.

Silver Nanoparticles as Antifungal Agents in Acrylic Latexes: Influence of the Initiator Type on Nanoparticle Incorporation and Aureobasidium pullulans Resistance

Discoloration of wood coatings due to fungal growth negatively affects the aesthetic properties of the coatings, and new ways to control fungal growth on coatings are needed. For this reason, silver nanoparticles (AgNPs) have been incorporated in acrylic latexes as antifungal agents. Using miniemulsion polymerization, latexes were prepared with two types of initiators (hydrophilic and hydrophobic) to assess the influence of the initiator type on AgNPs dispersion, both within the latex particles and the dry film. In addition, the impact of NP dispersion on resistance to black-stain fungi (Aureobasidium pullulans) was also evaluated. Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis indicates that acrylic latexes prepared with azobisisobutyronitrile (AIBN) as the initiator contain more AgNPs than those prepared with potassium persulfate (KPS). Cryo-TEM and SEM analyses show that the distribution of the AgNPs within the polymer particles is influenced by the nature of the initiator. When AIBN, a hydrophobic initiator, is used, the AgNPs appear to be closer to the surface of the polymer particles and more evenly distributed. However, the antifungal efficiency of the AgNPs-embedded latexes against A. pullulans is found to be higher when KPS is used, despite this initiator leading to a smaller amount of incorporated AgNPs and a less uniform dispersion of the nanoparticles.

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.

Ceria Nanoparticles Alleviated Osteoarthritis through Attenuating Senescence and Senescence-Associated Secretory Phenotype in Synoviocytes

Accumulation of senescent cells is the prominent risk factor for osteoarthritis (OA), accelerating the progression of OA through a senescence-associated secretory phenotype (SASP). Recent studies emphasized the existence of senescent synoviocytes in OA and the therapeutic effect of removing senescent synoviocytes. Ceria nanoparticles (CeNP) have exhibited therapeutic effects in multiple age-related diseases due to their unique capability of ROS scavenging. However, the role of CeNP in OA remains unknown. Our results revealed that CeNP could inhibit the expression of senescence and SASP biomarkers in multiple passaged and hydrogen-peroxide-treated synoviocytes by removing ROS. In vivo, the concentration of ROS in the synovial tissue was remarkably suppressed after the intra-articular injection of CeNP. Likewise, CeNP reduced the expression of senescence and SASP biomarkers as determined by immunohistochemistry analysis. The mechanistic study showed that CeNP inactivated the NFκB pathway in senescent synoviocytes. Finally, safranin O-fast green staining showed milder destruction of articular cartilage in the CeNP-treated group compared with the OA group. Overall, our study suggested that CeNP attenuated senescence and protected cartilage from degeneration via scavenging ROS and inactivating the NFκB signaling pathway. This study has potentially significant implications in the field of OA as it provides a novel strategy for OA treatment.

An Update on Novel Ocular Nanosystems with Possible Benefits in the Treatment of Corneal Neovascularization

Corneal neovascularization (CNV) is an ocular pathological change that results from an imbalance between angiogenic factors and antiangiogenic factors as a result of various ocular insults, including infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation. Current clinical strategies for the treatment of CNV include pharmacological treatment and surgical intervention. Despite some degree of success, the current treatment strategies are restricted by limited efficacy, adverse effects, and a short duration of action. Recently, gene-based antiangiogenic therapy has become an emerging strategy that has attracted considerable interest. However, potential complications with the use of viral vectors, such as potential genotoxicity resulting from long-term expression and nonspecific targeting, cannot be ignored. The use of ocular nanosystems (ONS) based on nanotechnology has emerged as a great advantage in ocular disease treatment during the last two decades. The potential functions of ONS range from nanocarriers, which deliver drugs and genes to target sites in the eye, to therapeutic agents themselves. Various preclinical studies conducted to date have demonstrated promising results of the use of ONS in the treatment of CNV. In this review, we provide an overview of CNV and its current therapeutic strategies and summarize the properties and applications of various ONS related to the treatment of CNV reported to date. Our goal is to provide a comprehensive review of these considerable advances in ONS in the field of CNV therapy over the past two decades to fill the gaps in previous related reports. Finally, we discuss existing challenges and future perspectives of the use of ONS in CNV therapy, with the goal of providing a theoretical contribution to facilitate future practical growth in the area.