Ethylene glycol coated nanoceria protects against oxidative stress in human lens epithelium

Green synthesis of nanoceria using Terminalia Arjuna extract for enhanced stability, antioxidant, and anticancer properties than their chemical counterparts

Nanoceria, a potent nanozyme, widely explored for biomedical applications, often faces toxicity and stability issues when synthesized chemically. In this study, nanoceria (NC-G) is synthesized via a simple green method using Terminalia arjuna extract as a reducing and capping agent and is compared with chemically synthesized nanoceria (NC-C) for stability, antioxidant, and anti-cancer properties. The mean sizes and surface charge of NC-C and NC-G was found to be 37.78 ± 15.5 nm (-16.2 ± 7.6 mV) and 21.8 ± 5.3 nm (-51.4 ± 8.9 mV) respectively. The percentage of Ce 3 + and Ce 4+ was determined using XPS analyses. Superoxide dismutase (SOD), catalase and antioxidant regenerative properties of NC-G was determined to have better performance than NC-C. Thus, NC-G demonstrated an improvement in cyto-compatibility when compared to NC-C using MTT assay. Moreover, NC-G showed enhanced intracellular antioxidant and cyto-protective properties under oxidative stress in rat cardiomyocytes cell line (H9C2). Further, both NC-C and NC-G showed dose-dependent anti-cancerous activity towards human breast cancer cell line (MCF7), with NC-G demonstrating enhanced pro-oxidant properties on MCF7 cells. The results from this study indicate that NC-G could be a potential nanomedicine as an antioxidant therapy in cardiovascular diseases or as pro-oxidant therapeutics in oncology.

New insights of cerium oxide nanoparticles in head and neck cancer treatment

Head and neck cancer (HNC) is a genetically complex cancer type having treatment difficulties due to affecting multiple organs in complex anatomical sites. Radiotherapy resistance, chemotoxicity, post-surgery disability makes HNC treatment more complicated. Therefore, there is need to developed new treatment approaches. Nanoparticle-based therapies especially cerium oxide nanoparticles with its anti-cancer features, high catalytic activity, anti- or pro-oxidant and radio-protective properties give a boon for HNC treatment. In the current study, two dextran-coated cerium oxide nanoparticles (Dex-CeNPs) namely SD1 and SD2 were synthesized and characterized by using two types of dextran (D1 and D2) having distinct molecular weights and branching characteristics to understand their potential as a new HNC treatment strategy while evaluating the role of dextran type. The effectivity of the SD1 and SD2 on the HNC cell lines (A253, SCC-25, FaDu) were investigated by analyzing their cytotoxicity, genotoxicity, reactive oxygen species (ROS) generation properties. Low IC50 value, high ROS generation and stability profiling of SD2 compared to SD1 indicates the distinct function of dextran type on Dex-CeNPs effectivity on HNC. To better elucidate the effectivity of SD2, flow cytometry analysis and pro-apoptotic (TP53, CASP3, BAX) and anti-apoptotic (Bcl-2) gene expression profiling were investigated in detail. The findings indicate that SD2 exhibits an influence on head and neck cancer cells via the apoptotic pathway. Our research sets the framework for the development of Dex-CeNPs as remarkable nanotherapeutic candidates for treatment of head and neck cancer.

Nanotherapy for Neural Retinal Regeneration

Retinal diseases can severely impair vision and even lead to blindness, posing significant threats to both physical and mental health. Physical retinal regenerative therapies are poised to revolutionize the treatment of various disorders associated with blindness. However, these therapies must overcome the challenges posed by the protective inner and outer blood‒retinal barriers. Nanotechnology applications in ophthalmology have shown great potential in addressing the issue of drug delivery to the eye. Moreover, nanotechnology-based therapeutics can have profound clinical impacts on retinopathy, particularly retinal regeneration, thereby improving patient outcomes. Continuous advancements in nanotechnology are being applied to regenerate lost or damaged eye tissues and to treat vision loss and blindness caused by various retinal degenerative diseases. These approaches can be categorized into three main strategies: i) nanoparticles for delivering drugs, genes, and other essential substances; ii) nanoscaffolds for providing biocompatible support; and iii) nanocomposites for enhancing the functionality of primary or stem cells. The aim of this comprehensive review is to present the current understanding of nanotechnology-based therapeutics for retinal regeneration, with a focus on the perspective functions of nanomaterials.

Dual Crosslinked Antioxidant Mixture of Poly(vinyl alcohol) and Cerium Oxide Nanoparticles as a Bioink for 3D Bioprinting

Three-dimensional (3D) bioprinting has made it possible to fabricate structures with intricate morphologies and architectures, which is considered difficult to do when using other conventional techniques like electrospinning. Although the 3D printing of thermoplastics has seen a huge boom in the past few years, it has been challenging to translate this technology to cell-based printing. A major limitation in bioprinting is the lack of inks that allow for the printing of 3D structures that meet the biological requirements of a specific organ or tissue. A bioink is a viscous polymer solution that cells are incorporated into before printing. Therefore, a bioink must have specific characteristics to ensure both good printability and biocompatibility. Despite the progress that has been made in bioprinting, achieving a balance between these two properties has been difficult. In this work, we developed a multimodal bioink that serves as both a cell carrier and a free radical scavenger for treating peripheral nerve injury. This bioink comprises poly(vinyl alcohol) (PVA) and cerium oxide nanoparticles (also called nanoceria (NC)) and was developed with a dual crosslinking method that utilizes citric acid and sodium hydroxide. By employing this dual crosslinking method, good printability of the bioink and shape fidelity of the bioprinted structure were achieved. Additionally, a cell viability study demonstrated that the cells remained compatible and viable even after they underwent the printing process. The combination of this PVA/NC bioink and the dual crosslinking method proved to be effective in enhancing printability and cell biocompatibility for extrusion-based bioprinting applications.

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

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

Silica Coated Bi2Se3 Topological Insulator Nanoparticles: An Alternative Route to Retain Their Optical Properties and Make Them Biocompatible

Localized surface plasmon resonance (LSPR) is the cause of the photo-thermal effect observed in topological insulator (TI) bismuth selenide (Bi₂Se₃) nanoparticles. These plasmonic properties, which are thought to be caused by its particular topological surface state (TSS), make the material interesting for application in the field of medical diagnosis and therapy. However, to be applied, the nanoparticles have to be coated with a protective surface layer, which prevents agglomeration and dissolution in the physiological medium. In this work, we investigated the possibility of using silica as a biocompatible coating for Bi₂Se₃ nanoparticles, instead of the commonly used ethylene-glycol, which, as is presented in this work, is not biocompatible and alters/masks the optical properties of TI. We successfully prepared Bi₂Se₃ nanoparticles coated with different silica layer thicknesses. Such nanoparticles, except those with a thick, ≈200 nm silica layer, retained their optical properties. Compared to ethylene-glycol coated nanoparticles, these silica coated nanoparticles displayed an improved photo-thermal conversion, which increased with the increasing thickness of the silica layer. To reach the desired temperatures, a 10-100 times lower concentration of photo-thermal nanoparticles was needed. In vitro experiments on erythrocytes and HeLa cells showed that, unlike ethylene glycol coated nanoparticles, silica coated nanoparticles are biocompatible.

Microfluidic-Based Formulation of Essential Oils-Loaded Chitosan Coated PLGA Particles Enhances Their Bioavailability and Nematocidal Activity

In this study, poly (lactic-co-glycolic) acid (PLGA) particles were synthesized and coated with chitosan. Three essential oil (EO) components (eugenol, linalool, and geraniol) were entrapped inside these PLGA particles by using the continuous flow-focusing microfluidic method and a partially water-miscible solvent mixture (dichloromethane: acetone mixture (1:10)). Encapsulation of EO components in PLGA particles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction, with encapsulation efficiencies 95.14%, 79.68%, and 71.34% and loading capacities 8.88%, 8.38%, and 5.65% in particles entrapped with eugenol, linalool, and geraniol, respectively. The EO components’ dissociation from the loaded particles exhibited an initial burst release in the first 8 h followed by a sustained release phase at significantly slower rates from the coated particles, extending beyond 5 days. The EO components encapsulated in chitosan coated particles up to 5 μg/mL were not cytotoxic to bovine gut cell line (FFKD-1-R) and had no adverse effect on cell growth and membrane integrity compared with free EO components or uncoated particles. Chitosan coated PLGA particles loaded with combined EO components (10 µg/mL) significantly inhibited the motility of the larval stage of Haemonchus contortus and Trichostrongylus axei by 76.9%, and completely inhibited the motility of adult worms (p < 0.05). This nematocidal effect was accompanied by considerable cuticular damage in the treated worms, reflecting a synergistic effect of the combined EO components and an additive effect of chitosan. These results show that encapsulation of EO components, with a potent anthelmintic activity, in chitosan coated PLGA particles improve the bioavailability and efficacy of EO components against ovine gastrointestinal nematodes.

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.

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.

Nanoceria Prevents Glucose-Induced Protein Glycation in Eye Lens Cells

Cerium oxide nanoparticles (nanoceria) are generally known for their recyclable antioxidative properties making them an appealing biomaterial for protecting against physiological and pathological age-related changes that are caused by reactive oxygen species (ROS). Cataract is one such pathology that has been associated with oxidation and glycation of the lens proteins (crystallins) leading to aggregation and opacification. A novel coated nanoceria formulation has been previously shown to enter the human lens epithelial cells (HLECs) and protect them from oxidative stress induced by hydrogen peroxide (H2O2). In this work, the mechanism of nanoceria uptake in HLECs is studied and multiple anti-cataractogenic properties are assessed in vitro. Our results show that the nanoceria provide multiple beneficial actions to delay cataract progression by (1) acting as a catalase mimetic in cells with inhibited catalase, (2) improving reduced to oxidised glutathione ratio (GSH/GSSG) in HLECs, and (3) inhibiting the non-enzymatic glucose-induced glycation of the chaperone lens protein α-crystallin. Given the multifactorial nature of cataract progression, the varied actions of nanoceria render them promising candidates for potential non-surgical therapeutic treatment.

Cerium Oxide Nanoparticles (Nanoceria): Hopes in Soft Tissue Engineering

Several biocompatible materials have been applied for managing soft tissue lesions; cerium oxide nanoparticles (CNPs, or nanoceria) are among the most promising candidates due to their outstanding properties, including antioxidant, anti-inflammatory, antibacterial, and angiogenic activities. Much attention should be paid to the physical properties of nanoceria, since most of its biological characteristics are directly determined by some of these relevant parameters, including the particle size and shape. Nanoceria, either in bare or functionalized forms, showed the excellent capability of accelerating the healing process of both acute and chronic wounds. The skin, heart, nervous system, and ophthalmic tissues are the main targets of nanoceria-based therapies, and the other soft tissues may also be evaluated in upcoming experimental studies. For the repair and regeneration of soft tissue damage and defects, nanoceria-incorporated film, hydrogel, and nanofibrous scaffolds have been proven to be highly suitable replacements with satisfactory outcomes. Still, some concerns have remained regarding the long-term effects of nanoceria administration for human tissues and organs, such as its clearance from the vital organs. Moreover, looking at the future, it seems necessary to design and develop three-dimensional (3D) printed scaffolds containing nanoceria for possible use in the concepts of personalized medicine.

Treatment of Human Lens Epithelium with High Levels of Nanoceria Leads to Reactive Oxygen Species Mediated Apoptosis

Nanoceria (cerium oxide nanoparticles) have been shown to protect human lens epithelial cells (HLECs) from oxidative stress when used at low concentrations. However, there is a lack of understanding about the mechanism of the cytotoxic and genotoxic effects of nanoceria when used at higher concentrations. Here, we investigated the impact of 24-hour exposure to nanoceria in HLECs. Nanoceria's effects on basal reactive oxygen species (ROS), mitochondrial morphology, membrane potential, ATP, genotoxicity, caspase activation and apoptotic hallmarks were investigated. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) studies on isolated mitochondria revealed significant uptake and localization of nanoceria in the mitochondria. At high nanoceria concentrations (400 µg mL-1), intracellular levels of ROS were increased and the HLECs exhibited classical hallmarks of apoptosis. These findings concur with the cells maintaining normal ATP levels necessary to execute the apoptotic process. These results highlight the need for nanoceria dose-effect studies on a range of cells and tissues to identify therapeutic concentrations in vitro or in vivo.