One-pot hydrothermal synthesis of fluorophore-modified cerium oxide nanoparticles.

Cerium oxide nanoparticles (CeO2 NPs), which have powerful antioxidant properties, are promising nanomaterials for the treatment of diseases associated with oxidative stress. The well-developed surface of CeO2 NPs makes them promising for use as a multifunctional system for various biomedical applications. This work demonstrates a simple approach that allows the direct formation of a molecular fluorophore on the surface of CeO2 NPs using a simple one-pot hydrothermal synthesis. Thus, we were able to synthesize CeO2 NPs of ultra-small size ∼2 nm with a narrow distribution, highly stable fluorescence, and a quantum yield of ∼62%. UV-visible transmission studies revealed that the resulting CeO2 NPs exhibited fast autogenerative catalytic reduction. In vitro results showed high biocompatibility of CeO2 NPs; their internalization occurs mainly in the region of cell nuclei. Thus, the resulting NPs have the necessary parameters and can be successfully used in biovisualization and therapy.

An Experimental Model of Proton-Beam-Induced Radiation Dermatitis In Vivo.

Radiation dermatitis (RD) is one of the most common side effects of radiation therapy. However, to date, there is a lack of both specific treatments for RD and validated experimental animal models with the use of various sources of ionizing radiation (IR) applied in clinical practice. The aim of this study was to develop and validate a model of acute RD induced using proton radiation in mice. Acute RD (Grade 2-4) was obtained with doses of 30, 40, and 50 Gy, either with or without depilation. The developed model of RD was characterized by typical histological changes in the skin after irradiation. Moreover, the depilation contributed to a skin histology alteration of the irradiated mice. The assessment of animal vital signs indicated that there was no effect of proton irradiation on the well-being or general condition of the animals. This model can be used to develop effective therapeutic agents and study the pathogenesis of radiation-induced skin toxicity, including that caused by proton irradiation.

Hybrid Polyelectrolyte Capsules Loaded with Gadolinium-Doped Cerium Oxide Nanoparticles as a Biocompatible MRI Agent for Theranostic Applications.

Layer-by-layer (LbL) self-assembled polyelectrolyte capsules have demonstrated their unique advantages and capability in drug delivery applications. These ordered micro/nanostructures are also promising candidates as imaging contrast agents for diagnostic and theranostic applications. Magnetic resonance imaging (MRI), one of the most powerful clinical imaging modalities, is moving forward to the molecular imaging field and requires advanced imaging probes. This paper reports on a new design of MRI-visible LbL capsules, loaded with redox-active gadolinium-doped cerium oxide nanoparticles (CeGdO2-x NPs). CeGdO2-x NPs possess an ultrasmall size, high colloidal stability, and pronounced antioxidant properties. A comprehensive analysis of LbL capsules by TEM, SEM, LCSM, and EDX techniques was carried out. The research demonstrated a high level of biocompatibility and cellular uptake efficiency of CeGdO2-x-loaded capsules by cancer (human osteosarcoma and adenocarcinoma) cells and normal (human mesenchymal stem) cells. The LbL-based delivery platform can also be used for other imaging modalities and theranostic applications.

Metformin mitigates radiation toxicity exerting antioxidant and genoprotective properties.

The antidiabetic drug metformin (MF) exhibits redox-modulating effects in various pathologies associated with oxidative stress and mitigates ionizing radiation-induced toxicity, but the underlying mechanisms remain to be elucidated. Thus, we studied some radiomitigatory effects of MF and explored the possible mechanisms behind them. Highly sensitive luminescence methods and non-competitive enzyme-linked immunosorbent assay (ELISA) were used in in vitro studies, and in vivo the damage to bone marrow cells and its repair were assessed by the micronucleus test. In a solution, MF at concentrations exceeding 0.1 µM effectively intercepts •OH upon X-ray-irradiation, but does not react directly with H2O2. MF accelerates the decomposition of H2O2 catalyzed by copper ions. MF does not affect the radiation-induced formation of H2O2 in the solution of bovine gamma-globulin (BGG), but has a modulating effect on the generation of H2O2 in the solution of bovine serum albumin (BSA). MF at 0.05-1 mM decreases the radiation-induced formation of 8-oxoguanine in a DNA solution depending on the concentration of MF with a maximum at 0.25 mM. MF at doses of 3 mg/kg body weight (bw) and 30 mg/kg bw administered to mice after irradiation, but not before irradiation, reduces the frequency of micronucleus formation in polychromatophilic erythrocytes of mouse red bone marrow. Our work has shown that the radiomitigatory properties of MF are mediated by antioxidant mechanisms of action, possibly including its ability to chelate polyvalent metal ions.

Heavily Gd-Doped Non-Toxic Cerium Oxide Nanoparticles for MRI Labelling of Stem Cells.

Recently, human mesenchymal stem cells (hMSc) have attracted a great deal of attention as potential therapeutic agents in the treatment of socially significant diseases. Despite substantial advances in stem-cell therapy, the biological mechanisms of hMSc action after transplantation remain unclear. The use of magnetic resonance imaging (MRI) as a non-invasive method for tracking stem cells in the body is very important for analysing their distribution in tissues and organs, as well as for ensuring control of their lifetime after injection. Herein, detailed experimental data are reported on the biocompatibility towards hMSc of heavily gadolinium-doped cerium oxide nanoparticles (Ce0.8Gd0.2O2-x) synthesised using two synthetic protocols. The relaxivity of the nanoparticles was measured in a magnetic field range from 1 mT to 16.4 T. The relaxivity values (r1 = 11 ± 1.2 mM-1 s-1 and r1 = 7 ± 1.2 mM-1 s-1 in magnetic fields typical of 1.5 and 3 T MRI scanners, respectively) are considerably higher than those of the commercial Omniscan MRI contrast agent. The low toxicity of gadolinium-doped ceria nanoparticles to hMSc enables their use as an effective theranostic tool with improved MRI-contrasting properties.

Redox-Active Cerium Fluoride Nanoparticles Selectively Modulate Cellular Response against X-ray Irradiation In Vitro.

Ionizing radiation-induced damage in cancer and normal cells leads to apoptosis and cell death, through the intracellular oxidative stress, DNA damage and disorders of their metabolism. Irradiation doses that do not lead to the death of tumor cells can result in the emergence of radioresistant clones of these cells due to the rearrangement of metabolism and the emergence of new mutations, including those in the genes responsible for DNA repair. The search for the substances capable of modulating the functioning of the tumor cell repair system is an urgent task. Here we analyzed the effect of cerium(III) fluoride nanoparticles (CeF3 NPs) on normal (human mesenchymal stem cells-hMSC) and cancer (MCF-7 line) human cells after X-ray radiation. CeF3 NPs effectively prevent the formation of hydrogen peroxide and hydroxyl radicals in an irradiated aqueous solution, showing pronounced antioxidant properties. CeF3 NPs are able to protect hMSC from radiation-induced proliferation arrest, increasing their viability and mitochondrial membrane potential, and, conversely, inducing the cell death of MCF-7 cancer cells, causing radiation-induced mitochondrial hyperpolarization. CeF3 NPs provided a significant decrease in the number of double-strand breaks (DSBs) in hMSC, while in MCF-7 cells the number of γ-H2AX foci dramatically increased in the presence of CeF3 4 h after irradiation. In the presence of CeF3 NPs, there was a tendency to modulate the expression of most analyzed genes associated with the development of intracellular oxidative stress, cell redox status and the DNA-repair system after X-ray irradiation. Cerium-containing nanoparticles are capable of providing selective protection of hMSC from radiation-induced injuries and are considered as a platform for the development of promising clinical radioprotectors.

The Strong Protective Action of Ce3+/F- Combined Treatment on Tooth Enamel and Epithelial Cells.

We studied the toxic effects of cerium and fluoride species on human dental pulp stem cells and epithelial cells of Cercopithecus aethiops as a surrogate for the human oral mucosa. The sequential use of CeCl3 and NH4F solutions in equimolar sub-toxic concentrations enabled the possible toxic effects of individual components to be avoided, ensuring the preservation of the metabolic activity of the cells due to the formation of CeF3 nanoparticles. Cerium fluoride nanoparticles and terbium-doped cerium fluoride nanoparticles exhibited neither cytotoxicity nor genotoxicity to dental pulp stem cells, even at high concentrations (10-4 M). In millimolar concentrations (from 10-5-10-6 M), these nanoparticles significantly increased the expression of genes responsible for the cell cycle, differentiation and proliferation. The formation of cerium fluoride on the surface of the mucous membrane and teeth provided protection against the development of carious lesions, periodontitis, ROS attacks and other inflammatory diseases of the oral cavity. Luminescent CeF3: Tb nanoparticles enabled the visualization of tooth enamel microcracks.

Novel Antioxidant, Deethylated Ethoxyquin, Protects against Carbon Tetrachloride Induced Hepatotoxicity in Rats by Inhibiting NLRP3 Inflammasome Activation and Apoptosis.

Inflammation and an increase in antioxidant responses mediated by oxidative stress play an important role in the pathogenesis of acute liver injury (ALI). We utilized in silico prediction of biological activity spectra for substances (PASS) analysis to estimate the potential biological activity profile of deethylated ethoxyquin (DEQ) and hypothesized that DEQ exhibits antioxidant and anti-inflammatory effects in a rat model of carbon tetrachloride (CCl4)-induced ALI. Our results demonstrate that DEQ improved liver function which was indicated by the reduction of histopathological liver changes. Treatment with DEQ reduced CCl4-induced elevation of gene expression, and the activity of antioxidant enzymes (AEs), as well as the expression of transcription factors Nfe2l2 and Nfkb2. Furthermore, DEQ treatment inhibited apoptosis, downregulated gene expression of pro-inflammatory cytokines (Tnf and Il6), cyclooxygenase 2 (Ptgs2), decreased glutathione (GSH) level and myeloperoxidase (MPO) activity in rats with ALI. Notably, DEQ treatment led to an inhibition of CCl4-induced NLRP3-inflammasome activation which was indicated by the reduced protein expression of IL-1ß, caspase-1, and NLRP3 in the liver. Our data suggest that DEQ has a hepatoprotective effect mediated by redox-homeostasis regulation, NLRP3 inflammasome, and apoptosis inhibition, which makes that compound a promising candidate for future clinical studies.

The first inorganic mitogens: Cerium oxide and cerium fluoride nanoparticles stimulate planarian regeneration via neoblastic activation.

We report the first experimental evidence for the mitogenic action of cerium(IV) oxide and cerium(III) fluoride nanoparticles (CONs and CFNs) on the regeneration of a whole organism - freshwater flatworms Schmidtea mediterranea (planarian). Both types of cerium-containing nanoparticles are shown to be a highly potent mitogen for planaria. Both CONs and CFNs, in micro- and nanomolar concentrations, markedly accelerate planarian blastema growth, due to the enhancement of cellular proliferation, causing an increase in the mitotic index and in the quantity of blastema cells in regenerating planaria. CONs provided maximum activity at concentrations which were two orders of magnitude lower than those for CeF3. The valence state of cerium in cerium-containing nanoparticles plays a significant role in the planarian regeneration mechanism: CeO2 nanoparticles containing predominantly Ce4+ species presumably scavenge wound induced reactive oxygen species and moderately activate gene expression processes, while the regenerative action of CeF3 nanoparticles containing only Ce3+ species is manifested in the pronounced expression of the genes involved in cell division, differentiation and migration. This is the first report on the effect of cerium-containing nanoparticles on tissue regeneration in vivo, further revealing the mechanisms of their biological action, which enhances the possibility of their use in cellular technologies.

Ceria Nanoparticles-Decorated Microcapsules as a Smart Drug Delivery/Protective System: Protection of Encapsulated P. pyralis Luciferase.

The design of novel, effective drug delivery systems is one of the most promising ways to improve the treatment of socially important diseases. This article reports on an innovative approach to the production of composite microcontainers (microcapsules) bearing advanced protective functions. Cerium oxide (CeO2) nanoparticles were incorporated into layer-by-layer polyelectrolyte microcapsules as a protective shell for an encapsulated enzyme (luciferase of Photinus pyralis), preventing its oxidation by hydrogen peroxide, the most abundant type of reactive oxygen species (ROS). The protective effect depends on CeO2 loading in the shell: at a low concentration, CeO2 nanoparticles only scavenge ROS, whereas a higher content leads to a decrease in access for both ROS and the substrate to the enzyme in the core. By varying the nanoparticle concentration in the microcapsule, it is possible to control the level of core shielding, from ROS filtering to complete blocking. A comprehensive analysis of microcapsules by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, confocal laser scanning microscopy, and energy-dispersive X-ray spectroscopy techniques was carried out. Composite microcapsules decorated with CeO2 nanoparticles and encapsulated luciferase were shown to be easily taken up by rat B-50 neuronal cells; they are nontoxic and are able to protect cells from the oxidative stress induced by hydrogen peroxide. The approach demonstrated that the active protection of microencapsulated substances by CeO2 nanoparticles can be used in the development of new drug delivery and diagnostic systems.

Intracellular Delivery of Antioxidant CeO2 Nanoparticles via Polyelectrolyte Microcapsules.

Cerium oxide nanoparticles (nanoceria) are regarded as one of the most promising inorganic antioxidants for biomedical applications. Considering nanoceria as a potential therapeutic agent, we aimed to develop a robust system for its intracellular delivery using layer-by-layer polyelectrolyte microcapsules. We have shown that citrate-stabilized cerium oxide nanoparticles can be effectively incorporated into the structure of polyelectrolyte microcapsules made from biodegradable and nonbiodegradable polymers. The structure and morphology of synthesized microcapsules were investigated and analyzed using confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and UV/vis spectroscopy. Results of experiments in vitro on B50 neuroblastoma cells confirmed nanoceria delivery into the cell while maintaining their antioxidant properties. The results presented confirm polyelectrolyte microcapsules to be an efficient intracellular delivery system for therapeutic nanoparticles.

Triterpenoid saponins from the roots of Acanthophyllum gypsophiloides Regel.

Two new triterpenoid saponins 1 and 2 were isolated from the methanol extract of the roots of Acanthophyllum gypsophiloides Regel. These saponins have quillaic acid or gypsogenin moieties as an aglycon, and both bear similar sets of two oligosaccharide chains, which are 3-O-linked to the triterpenoid part trisaccharide α-L-Arap-(1→3)-[α-D-Galp-(1→2)]-ß-D-GlcpA and pentasaccharide ß-D-Xylp-(1→3)-ß-D-Xylp-(1→3)-α-L-Rhap-(1→2)-[ß-D-Quip-(1→4)]-ß-D-Fucp connected through an ester linkage to C-28. The structures of the obtained saponins were elucidated by a combination of mass spectrometry and 2D NMR spectroscopy. A study of acute toxicity, hemolytic, anti-inflammatory, immunoadjuvant and antifungal activity was carried out. Both saponins 1 and 2 were shown to exhibit immunoadjuvant properties within the vaccine composition with keyhole limpet hemocyanin-based immunogen. The availability of saponins 1 and 2 as individual pure compounds from the extract of the roots of A. gypsophiloides makes it a prospective source of immunoactive agents.

Reduced Walker 256 carcinosarcoma growth in vasopressin-deficient Brattleboro rats.

The growth pattern of carcinosarcoma Walker 256 was studied in rats with different levels of vasopressin in the blood. The Brattleboro rats are unable to synthesize vasopressin in a consequence of deletion in the coding gene. Hybrids from crossbreeding of the mutant Brattleboro and normal WAG rats inherit the one intact vasopressin gene and hold nearly normal hormone level. It was found that non-strain-specific carcinosarcoma Walker 256 intensively grows in WAG rats and their offsprings from crossbreeding with Brattleboro rats, and tumor development is equally terminated in them by death. Carcinosarcoma grows less intensely in Brattleboro rats; the tumor nodes increased only within the first 2 weeks, after which, the tumor began to decrease and eventually disappeared. Infusion of exogenous vasopressin to Brattleboro rats intensifies a tumor growth in the first 2 weeks after the inoculation of Walker 256 cells; however, it does not prevent a following regression and resorption of tumors.