Humic acid-nanoceria composite as a sustainable adsorbent for simultaneous removal of uranium(VI), chromium(VI), and fluoride ions from aqueous solutions

In this article, the multifunctional behavior of novel, efficient, and cost-effective humic acid-coated nanoceria (HA@CeO2 NPs) was utilized for the sorptive removal of U(VI), Cr(VI), and F- ions at different conditions. The production cost of HA@CeO2 was $19.28/kg and was well characterized by DLS, FESEM, HRTEM, FTIR, XRD, XPS, and TGA. Batch adsorption study for U(VI) (at pH ~ 8), Cr(VI) (at pH ~ 1), and F- (at pH ~ 2) revealed that the maximum percentage of sorption was > 80% for all the cases. From the contact time experiment, it was concluded that pseudo-second-order kinetics followed, and hence, the process should be a chemisorption. The adsorption study revealed that U(VI) and Cr(VI) followed the Freundlich isotherm, whereas F- followed the Langmuir isotherm. Maximum adsorption capacity for F- was 96 mg g-1. Experiments in real water suggest that adsorption is decreased in Kaljani River water (~ 12% for Cr(VI) and ~ 11% for F-) and Kochbihar Lake water (25.04% for Cr(VI) and 20.5% for F-) because of competing ion effect. Mechanism was well established by the kinetic study as well as XPS analysis. Because of high adsorption efficiency, HA@CeO2 NPs can be used for the removal of other harmful water contaminants to make healthy aquatic life as well as purified drinking water.

Antioxidant nanozymes as next-generation therapeutics to free radical-mediated inflammatory diseases: A comprehensive review

Recent developments in exploring the biological enzyme mimicking properties in nanozymes have opened a separate avenue, which provides a suitable alternative to the natural antioxidants and enzymes. Due to high and tunable catalytic activity, low cost of synthesis, easy surface modification, and good biocompatibility, nanozymes have garnered significant research interest globally. Several inorganic nanomaterials have been investigated to exhibit catalytic activities of some of the key natural enzymes, including superoxide dismutase (SOD), catalase, glutathione peroxidase, peroxidase, and oxidase, etc. These nanozymes are used for diverse biomedical applications including therapeutics, imaging, and biosensing in various cells/tissues and animal models. In particular, inflammation-related diseases are closely associated with reactive oxygen and reactive nitrogen species, and therefore effective antioxidants could be excellent therapeutics due to their free radical scavenging ability. Although biological enzymes and other artificial antioxidants could perform well in scavenging the reactive oxygen and nitrogen species, however, suffer from several drawbacks such as the requirement of strict physiological conditions for enzymatic activity, limited stability in the environment beyond their optimum pH and temperature, and high cost of synthesis, purification, and storage make then unattractive for broad-spectrum applications. Therefore, this review systematically and comprehensively presents the free radical-mediated evolution of various inflammatory diseases (inflammatory bowel disease, mammary gland fibrosis, and inflammation, acute injury of the liver and kidney, mammary fibrosis, and cerebral ischemic stroke reperfusion) and their mitigation by various antioxidant nanozymes in the biological system. The mechanism of free radical scavenging by antioxidant nanozymes under in vitro and in vivo experimental models and catalytic efficiency comparison with corresponding natural enzymes has also been presented.

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.

Pegylated nanoceria: A versatile nanomaterial for noninvasive treatment of retinal diseases

Oxidative stress induced reactive oxygen species has been implicated as the primary molecular mechanism in the pathogenesis of debilitating retinal diseases such as diabetic retinopathy, neovascularization and age-related macular degeneration. Nanoceria (cerium oxide nanoparticles) has recently received much attention, because of its superior and regenerative radical scavenging properties. This review focuses on retinal applications of nanoceria and functionalized nanoceria. Studies in animal models showed that nanoceria possess antioxidant, anti-inflammatory, anti-angiogenic, anti-apoptotic properties and preserves retinal morphology and prevents loss of retinal functions. Nanoceria have been tested in animal models of age-related macular degeneration and neovascularization and their efficacy have been shown to persist for a long time, without any collateral effects. To date, several pharmaceutical formulations of nanoceria have been developed for their prospective clinical ophthalmic applications such as chitosan coated nanoceria, nanoceria loaded into hydrogels, nanoceria embedded in wafers and contact lens and organosilane or polyethylene glycol functionalized nanoceria. Based on their nano size range, ocular permeation could be achieved to allow topical administration of nanoceria. PEGylation of nanoceria represents the key strategy to support eye drop formulation with enhanced corneal permeation, without altering chemical physical properties. Based on their excellent antioxidant properties, nano-size, safety and tolerability, PEGylated nanoceria represent a new potential therapeutic for the treatment.

Multifunctional dendrimer@nanoceria engineered GelMA hydrogel accelerates bone regeneration through orchestrated cellular responses

Bone defects in patients entail the microenvironment that needs to boost the functions of stem cells (e.g., proliferation, migration, and differentiation) while alleviating severe inflammation induced by high oxidative stress. Biomaterials can help to shift the microenvironment by regulating these multiple events. Here we report multifunctional composite hydrogels composed of photo-responsive Gelatin Methacryloyl (GelMA) and dendrimer (G3)-functionalized nanoceria (G3@nCe). Incorporation of G3@nCe into GelMA could enhance the mechanical properties of hydrogels and their enzymatic ability to clear reactive oxygen species (ROS). The G3@nCe/GelMA hydrogels supported the focal adhesion of mesenchymal stem cells (MSCs) and further increased their proliferation and migration ability (vs. pristine GelMA and nCe/GelMA). Moreover, the osteogenic differentiation of MSCs was significantly stimulated upon the G3@nCe/GelMA hydrogels. Importantly, the capacity of G3@nCe/GelMA hydrogels to scavenge extracellular ROS enabled MSCs to survive against H₂O₂-induced high oxidative stress. Transcriptome analysis by RNA sequencing identified the genes upregulated and the signalling pathways activated by G3@nCe/GelMA that are associated with cell growth, migration, osteogenesis, and ROS-metabolic process. When implanted subcutaneously, the hydrogels exhibited excellent tissue integration with a sign of material degradation while the inflammatory response was minimal. Furthermore, G3@nCe/GelMA hydrogels demonstrated effective bone regeneration capacity in a rat critical-sized bone defect model, possibly due to an orchestrated capacity of enhancing cell proliferation, motility and osteogenesis while alleviating oxidative stress.

A comprehensive proteomics analysis of the response of Pseudomonas aeruginosa to nanoceria cytotoxicity

The increased commercial use and spread of nanoceria raises concerns about the risks associated with its effects on living organisms. Although Pseudomonas aeruginosa may be ubiquitous in nature, it is largely found in locations closely linked with human activity. P. aeruginosa san ai was used as a model organism for a deeper understanding of the interaction between biomolecules of the bacteria with this intriguing nanomaterial. A comprehensive proteomics approach along with analysis of altered respiration and production of targeted/specific secondary metabolites was conducted to study the response of P. aeruginosa san ai to nanoceria. Quantitative proteomics found that proteins associated with redox homeostasis, biosynthesis of amino acids, and lipid catabolism were upregulated. Proteins from outer cellular structures were downregulated, including transporters responsible for peptides, sugars, amino acids and polyamines, and the crucial TolB protein of the Tol-Pal system, required for the structural formation of the outer membrane layer. In accordance with the altered redox homeostasis proteins, an increased amount of pyocyanin, a key redox shuttle, and the upregulation of the siderophore, pyoverdine, responsible for iron homeostasis, were found. Production of extracellular molecules, e.g. pyocyanin, pyoverdine, exopolysaccharides, lipase, and alkaline protease, was significantly increased in P. aeruginosa san ai exposed to nanoceria. Overall, nanoceria at sublethal concentrations induces profound metabolic changes in P. aeruginosa san ai and provokes increased secretion of extracellular virulence factors, revealing the powerful influence this nanomaterial has on the vital functions of the microorganism.

Deep eutectic solvents-Hydrogels for the topical management of rheumatoid arthritis

Deep eutectic solvents (DES) have demonstrated their ability to facilitate skin penetrability of rigid nanoparticles (NPs). Here, we reported a feasible and simple transdermal delivery strategy using mesoporous silica nanoparticles impregnated in DES hydrogels for topical management of rheumatoid arthritis (RA). To achieve this goal, nanoceria was immobilized within a silica nanoparticle matrix (MSN) and encapsulated with methotrexate (MTX). The functionalized nanoparticles were first engineered in an Arginine (Arg)-citric acid (CA) DES and then transferred to the carbomer hydrogel matrix. Due to the strong affinity of DES hydrogels to the skin, combined with solvent-driven "Drag" effects, the prepared DES-MSNs hydrogels produced dynamic mobility of MSNs through skin layers, resulting in high skin penetrability. After application to the skin, the hydrogel solvent drove the rigid NPs across the skin barrier in a nonintrusive manner, resulting in sustained penetration and accumulation of MSNs at subcutaneous inflammation sites. Subsequently, the MTX payload exerted a direct therapeutic effect, while nanoceria moderated the inflammatory microenvironment by initiating reactive oxygen species (ROS) scavenging and transformation of the macrophage phenotype. In this way, the synergistic action of the combination of immuno- and chemotherapy of the drug and its carrier on RA was achieved. Our work provides a novel strategy for multisite regulation and controlled management of RA in a noninvasive way.

Ameliorative effects of clindamycin - nanoceria conjugate: A ROS responsive smart drug delivery system for diabetic wound healing study

BACKGROUND

Increased incidence of antibiotic-resistant species calls for development of new types of nano-medicine that can be used for healing of bacteria-caused wounds, such as diabetic foot ulcer. As diabetic patients have inefficient defense mechanism against reactive oxygen species (ROS) produced in our body as a by-product of oxygen reduction, the process of wound healing takes longer epithelialisation period. Ceria nanoparticles (CNPs) are well-known for their antibacterial and ROS-scavenging nature. Yet till now no significant effort has been made to conjugate ceria nanoparticles with drugs to treat diabetic wounds.

METHODS

In this experiment, CNPs were synthesized in-house and clindamycin hydrochloride was loaded onto it by physical adsorption method for reactive oxygen species responsive drug delivery. Various physico-chemical characterisations such as Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Energy dispersive X-ray, Thermogravimetric study etc. were performed to affirm the formation of both nanoceria along with drug encapsulated nanoceria.

RESULTS

Both of these as-prepared formulations inhibited the growth of Gram-positive as well as Gram-negative bacteria confirmed by Disk diffusion study; exhibiting their antibacterial effect. In-vitro drug release study was carried out in physiological environment both in absence and presence of hydrogen peroxide solution to test the reactive ROS-responsiveness of the drug loaded nanocomposites. It also exhibited faster wound healing in diabetes-induced rats. Therefore, it could successfully lower the amount of serum glucose level, inflammation cytokines, hepatotoxic and oxidative stress markers in diabetic rats as confirmed by various ex vivo tests conducted.

CONCLUSION

Thus, drug loaded ceria nanoparticles have the potential to heal diabetic wounds successfully and can be considered to be useful for the fabrication of appropriate medicated suppositories beneficial for diabetic foot ulcer treatment in future.

Nanoceria-GO-intercalated multicellular spheroids revascularize and salvage critical ischemic limbs through anti-apoptotic and pro-angiogenic functions

Critical limb ischemia (CLI) is a serious form of peripheral arterial disease that involves severe blockage of blood flow in lower extremities, often leading to foot necrosis and limb loss. Lack of blood flow and high pro-inflammation with overproduced reactive oxygen species (ROS) in CLI aggravate the degenerative events. Among other therapies, cell delivery is considered potential for restoring regenerative capacity, and preservation of cell survival under high oxidative stress has been challenging and prerequisite to harness cellular functions. Here, we introduce a multicellular delivery system that is intercalated with nanoceria-decorated graphene oxide (CeGO), which is considered to have high ROS scavenging ability while providing cell-matrix interaction signals. The CeGO nano-microsheets (8-nm-nanoceria/0.9-μm-GO) incorporated in HUVEC/MSC (7/3) could form cell-material hybrid spheroids mediated by cellular contraction. Under in vitro oxidative-stress-challenge with H₂O₂, the CeGO-intercalation enhanced the survival and anti-apoptotic capacity of cellular spheroids. Pro-angiogenic events of cellular spheroids, including cell sprouting and expression of angiogenic markers (HIF1α, VEGF, FGF2, eNOS) were significantly enhanced by the CeGO-intercalation. Proteomics analysis also confirmed substantial up-regulation of a series of angiogenesis-related secretome molecules. Such pro-angiogenic events with CeGO-intercalation were proven to be mediated by the APE/Ref-1 signaling pathway. When delivered to ischemic hindlimb in mice, the CeGO-cell spheroids could inhibit the accumulation of in vivo ROS rapidly, preserving high cell survival rate (cells were more proliferative and less apoptotic vs. those in cell-only spheroids), and up-regulated angiogenic molecular expressions. Monitoring over 28 days revealed significantly enhanced blood reperfusion and tissue recovery, and an ultimate limb salvage with the CeGO-cell delivery (∼60% salvaged vs. ∼29% in cell-only delivery vs. 0% in ischemia control). Together, the CeGO intercalated in HUVEC/MSC delivery is considered a potential nano-microplatform for CLI treatment, by scavenging excessive ROS and enhancing transplanted cell survival, while stimulating angiogenic events, which collectively help revascularization and tissue recovery, salvaging critical ischemic limbs.

Nanoceria as an Electron Reservoir: Spontaneous Deposition of Metal Nanoparticles on Oxides and Their Anti-inflammatory Activities

Designing metal-metal oxide heteronanostructures with synergistic and superior activities (unattainable in the case of a single entity) is of great interest for a wide range of technological applications. Traditional synthetic strategies typically require reducing agents, stabilizing ligands, or high temperature reductive treatment to produce oxide-supported metals. Herein, a facile noble metal deposition strategy is developed to produce silver, gold, and platinum nanocrystals on the surface of hollow mesoporous cerium oxide nanospheres without any pretreatment. Unlike the galvanic replacement reaction, the developed protocol employs the innate reductive potential of CeO₂ to produce a high density of ultrafine noble metal nanocrystals homogeneously immobilized onto the surface of CeO₂ nanospheres. The multienzyme-like activities (i.e., superoxide dismutase-like and catalase-like) of CeO₂@metal nanostructures, originating from CeO₂ and metal nanoparticles, were effectively utilized for anti-inflammatory therapies in two in vivo models. This oxygen vacancy-mediated reduction strategy can be generalized to produce diverse metal-metal oxide nanostructures for a wide range of applications.

Collaborative influence of morphology tuning and RE (La, Y, and Sm) doping on photocatalytic performance of nanoceria

Tuning morphology and doping additional rare earth (RE) cations are potential techniques to promote the photocatalytic performance of ceria (CeO₂), evaluating the collaborative effects of morphology and RE dopants is significant for producing high active ceria-based catalysts. So in this work, cubic, polyhedral and rod-like nanoceria doped with 10 mol % La (lanthanum), Y (yttrium), or Sm (samarium) were synthesized by a facile template-free hydrothermal method. Phases, morphologies, oxygen vacancies (OVs) concentration, energy band structure, photo-carriers separation/recombination, and photodegradation ratio toward methylene blue (MB) dye of as prepared ceria were studied. Results show that doped CeO₂ maintains a similar morphology structure with un-doped sample and the band gap narrows slightly. Y-doped nanoceria, with an improved separation and a reduced recombination of photo-excited electrons (e^-) and holes (h⁺), owns a higher MB photodegradation ratio than that of samples doping with La or Sm, which is measured as 79.04, 84.43, and 85.59% for Y-doped cubic, polyhedral, and rod-like CeO₂. The collaborative influence of morphology tuning and RE (La, Y, and Sm) doping on photocatalytic performance of nanoceria includes the effects of doped elements and the formation of OVs. The elevation of OVs concentration as well as the separation efficiency of photo-generated e^-/h⁺ are suggested to further enhance the photocatalytic performance of ceria.

Comparison of biodistribution of cerium oxide nanoparticles after repeated oral administration by gavage or snack in Sprague Dawley rats

The rate of translocation of ingested nanoparticles (NPs) and how the uptake is affected by a food matrix are key aspects of health risk assessment. In this study, female Sprague Dawley rats (N = 4/group) received 0, 1.4, or 13 mg of cerium oxide (CeO₂ NM-212) NPs/rat/day by gavage or in a chocolate spread snack 5 days/week for 1 or 2 weeks followed by 2 weeks of recovery. A dose and time-dependent uptake in the liver and spleen of 0.1-0.3 and 0.004-0.005 parts per million (ng/mg) of the total administered dose was found, respectively. There was no statistically significant difference in cerium concentration in the liver or spleen after gavage compared to snack dosing. Microscopy revealed indications of necrotic changes in the liver and decreased cellularity in white pulp in the spleen. The snack provided precise administration and a more human-relevant exposure of NPs and could improve animal welfare as alternative to gavage.

Multiomics analyses uncover nanoceria triggered oxidative injury and nutrient imbalance in earthworm Eisenia fetida

The toxic stress caused by nanoceria remains vague owing to the limited efforts scrutinizing its molecular mechanisms. Herein, we investigated the impacts of nanoceria on earthworm Eisenia fetida, at the molecular level using the multiomics-based profiling approaches (transcriptomics, metabolomics, and 16 S rRNA sequencing). Nanoceria (50 and 500 mg/kg) significantly increased the contents of malondialdehyde (MDA), Fe, and K in worms, suggesting oxidative injury and nutrient imbalance. This was corroborated by the transcriptomic and metabolomic analyses. Nanoceria decreased the levels of certain genes and metabolites associated with glycerolipid and glycerophospholipid metabolisms, suggesting the production of reactive oxygen species and subsequent oxidative stress. Additionally, the ABCD3 gene belonging to ABC transporter family was upregulated, facilitating Fe uptake by worms. Moreover, the higher contents of MDA, Fe, and K after exposure were tightly associated with the imbalanced intestinal flora. Specifically, a higher relative abundance of Actinobacteriota and a lower relative abundance of Proteobacteria and Patescibacteria were induced. This study, for the first time, revealed that nanoceria at nonlethal levels caused oxidative stress and nutrient imbalance of earthworms from the perspective of genes, metabolites, and gut microbiome perturbations, and also established links between the gut microbiome and the overall physiological responses of the host.

Biosynthesized Cerium Oxide Nanoparticles CeO2NPs: Recent Progress and Medical Applications

Currently, nanobiotechnology represents a leading research area that primarily focuses on the safe, eco-friendly synthesis of biocompatible metal oxide nanoparticles. Among these, biosynthesized cerium oxide nanoparticles have particularly received attention in medical science as their unique surface chemistry and dual oxidation state make them excellent antioxidants and free-radical scavengers. Currently, plant extracts are widely explored and employed for the biosynthesis of CeO2NPs. Other biological sources such as marine oyster shell extract, egg-white; biopolymers, e.g., chitosan, agarose, alginate, and others have also been successfully used for fabrication of CeO2NPs. This review highlights the recent progress in the biosynthesis of CeO2NPs and the investigation of their medical use as biocompatible anticancer, antibacterial, antifungal, antioxidant, antidiabetic, and wound healing agents. Furthermore, prospects associated with the use of biogenic CeO2NPs in developing novel products in the medical sector are also highlighted.

CeO2 nanoparticles improved cucumber salt tolerance is associated with its induced early stimulation on antioxidant system

Salinity is a global issue limiting efficient agricultural production. Nano-enabled plant salt tolerance is a hot topic. However, the role of nanoparticles induced possible early stimulation on antioxidant system in its improved plant salt tolerance is still largely unknown. Here, poly (acrylic) acid coated nanoceria (cerium oxide nanoparticles) (PNC, 7.8 nm, -31 mV) with potent ROS (reactive oxygen species) scavenging ability are used. Compared with control, no significant difference of H₂O₂ and O₂^•─ content, MDA (malondialdehyde) content, relative electric conductivity, and Fv/Fm was found in leaves and/or roots of cucumber before onset of salinity stress, regardless of leaf or root application of PNC. While, before onset of salinity stress, compared with control, the activities of SOD (superoxide dismutase, up to 1.8 folds change), POD (peroxidase, up to 2.5 folds change) and CAT (catalase, up to 2.3 folds change), and the content of GSH (glutathione, up to 3.0 folds change) and ASA (ascorbic acid, up to 2.4 folds change) in leaves and roots of cucumber with PNC leaf spray or root application were significantly increased. RNA seq analysis further confirmed that PNC foliar spray upregulates more genes in leaves over roots than the root application. These results showed that foliar sprayed PNC have stronger early stimulation effect on antioxidant system than the root applied one and leaf are more sensitive to PNC stimulation than root. After salt stress, cucumber plants with foliar sprayed PNC showed better improvement in salt tolerance than the root applied one. Also, plants with foliar sprayed PNC showed significant higher whole plant cerium content than the root applied one after salt stress. In summary, we showed that foliar spray of nanoceria is more optimal than root application in terms of improving cucumber salt tolerance, and this improvement is associated with better stimulation on antioxidant system in plants.

Synthesis of carbon dots from taurine as bioimaging agent and nanohybrid with ceria for antioxidant and antibacterial applications

Here we have synthesized water soluble and biocompatible carbon dots (CDs) from taurine via thermal decomposition method. The CDs showed nearly spherical shape with diameter less than 10 nm. The CDs exhibited excitation dependent fluorescence emission and could be used for mammalian cell imaging. The CDs showed excellent DPPH and hydrogen peroxide radical scavenging activity in cell free system. Besides, the CDs also displayed significant intracellular radical scavenging activity in human normal kidney epithelial (NKE) cells. Furthermore, nanohybrids consisting of both CDs and nanoceria (CeO₂) were prepared and tested for their biomedical applications. The nanohybrids showed significant antioxidant activities in both cell free and intracellular conditions. The CDs and nanohybrids possessed very little toxicity upto the concentration of 100 μg/mL when treated for 24 hours in human NKE cells. The CDs as well as nanohybrids further displayed significant bacterial growth inhibition against both gram-positive and gram-negative bacteria under dark as well as light illumination condition via the bacterial membrane damage. However, under the light illumination, the bacterial growth inhibition of CDs and nanohybrids was further enhanced due to the generation of reactive oxygen radicals and subsequent DNA degradation. A higher dose-dependent intracellular antioxidant and antibacterial activities of the nanohybrid is attributed to the synergistic effect of nanoceria and CDs. All these results clearly reflected that our synthesized CDs and their nanohybrids can be used for several biomedical applications.

Liquid crystal-based sensitive and selective detection of uric acid and uricase in body fluids

The abnormal levels of uric acid (UA) in body fluids are associated with gout, type (II) diabetes, leukemia, Lesch-Nyhan syndrome, uremia, kidney damage, and cardiovascular diseases. Also, the presence of uricase (UOx) symbolizes genetic disorders and corresponding complications. Therefore, the detection of UA and UOx in the body fluids is significant for clinical diagnosis. 4-Cyano-4'-pentylbiphenyl (5CB, a nematic liquid crystal (LC)) was doped with octadecyl trimethylammonium bromide (OTAB, a cationic surfactant), which formed a self-assembled monolayer at the aqueous/5CB interface. The UOx-catalyzed oxidation of UA yielded H₂O₂, releasing the single-strand deoxyribonucleic acid (ssDNA) from the nanoceria/ssDNA complex. The interaction of the released ssDNA with OTAB disrupted the monolayer at the aqueous/5CB interface, which resulted in a dark to bright change when observed through a polarized optical microscope. The LC-based sensor allowed the detection of UA with a linear range of 0.01-10 μM and a limit of detection (LOD) of 0.001 μM. The UA detection was also performed in human urine samples and the results were comparable to that of a standard commercial colorimetric method. Similarly, the detection of UOx was performed, with a noted linear range of 20-140 μg/mL. The LOD was as low as 0.34 μg/mL. The detection of UOx was also demonstrated in human serum samples with excellent performance. This method provides a robust sensing platform for the detection of UA and UOx and has potential for applications in clinical analysis.

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

Background

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

Results

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

Conclusions

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

Supplementary Information

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

Nanoceria-based lateral flow immunoassay for hydrogen peroxide-free colorimetric biosensing for C-reactive protein

During the recent several decades, lateral flow immunoassay (LFIA) constructed with gold nanoparticle (AuNP) has been widely utilized to conveniently detect target analyte. However, AuNP-based LFIA has limitations, such as limited detection sensitivity and quantification capability. Herein, to overcome these constraints, we have developed cerium oxide nanoparticle (nanoceria)-based LFIA for C-reactive protein (CRP) detection in human serum samples. It was fabricated with nanoceria, a notable nanozyme that shows an oxidase activity to quickly oxidize organic substrate, such as 3,3',5,5'-tetramethylbenzidine (TMB), to produce colored product without any oxidizing agent (e.g., hydrogen peroxide), which is advantageous for realizing point-of-care testing (POCT) applications. By employing human blood serum spiked with CRP, the nanoceria-based LFIA showed two blue-colored lines on the test and control region within 3 min via TMB oxidation, by the captured nanoceria through antigen-antibody interaction. The produced blue-colored lines were distinguished by naked eyes and quantitated with real images acquired by a conventional smartphone with the ImageJ software. With this strategy, target CRP was specifically determined down to 117 ng mL^-1 with high detection precisions yielding coefficient of variation of 9.8-11.3% and recovery of 90.7-103.2% using human blood serum samples. This investigation demonstrates the potential of oxidase-like nanoceria for developing LFIA, which is particularly useful in instrumentation-free POCT environments.

Nanoceria, the versatile nanoparticles: Promising biomedical applications

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

Nanoceria seed priming enhanced salt tolerance in rapeseed through modulating ROS homeostasis and α-amylase activities

BACKGROUND

Salinity is a big threat to agriculture by limiting crop production. Nanopriming (seed priming with nanomaterials) is an emerged approach to improve plant stress tolerance; however, our knowledge about the underlying mechanisms is limited.

RESULTS

Herein, we used cerium oxide nanoparticles (nanoceria) to prime rapeseeds and investigated the possible mechanisms behind nanoceria improved rapeseed salt tolerance. We synthesized and characterized polyacrylic acid coated nanoceria (PNC, 8.5 ± 0.2 nm, -43.3 ± 6.3 mV) and monitored its distribution in different tissues of the seed during the imbibition period (1, 3, 8 h priming). Our results showed that compared with the no nanoparticle control, PNC nanopriming improved germination rate (12%) and biomass (41%) in rapeseeds (Brassica napus) under salt stress (200 mM NaCl). During the priming hours, PNC were located mostly in the seed coat, nevertheless the intensity of PNC in cotyledon and radicle was increased alongside with the increase of priming hours. During the priming hours, the amount of the absorbed water (52%, 14%, 12% increase at 1, 3, 8 h priming, respectively) and the activities of α-amylase were significantly higher (175%, 309%, 295% increase at 1, 3, 8 h priming, respectively) in PNC treatment than the control. PNC primed rapeseeds showed significantly lower content of MDA, H2O2, and •O2- in both shoot and root than the control under salt stress. Also, under salt stress, PNC nanopriming enabled significantly higher K+ retention (29%) and significantly lower Na+ accumulation (18.5%) and Na+/K+ ratio (37%) than the control.

CONCLUSIONS

Our results suggested that besides the more absorbed water and higher α-amylase activities, PNC nanopriming improves salt tolerance in rapeseeds through alleviating oxidative damage and maintaining Na+/K+ ratio. It adds more knowledge regarding the mechanisms underlying nanopriming improved plant salt tolerance.

Nanoceria potently reduce superoxide fluxes from mitochondrial electron transport chain and plasma membrane NADPH oxidase in human macrophages

Cerium oxide nanoparticles, also known as nanoceria, possess antioxidative and anti-inflammatory activities in animal models of inflammatory disorders, such as sepsis. However, it remains unclear how nanoceria affect cellular superoxide fluxes in macrophages, a critical type of cells involved in inflammatory disorders. Using human ML-1 cell-derived macrophages, we showed that nanoceria at 1-100 μg/ml potently reduced superoxide flux from the mitochondrial electron transport chain (METC) in a concentration-dependent manner. The inhibitory effects of nanoceria were also shown in succinate-driven mitochondria isolated from the macrophages. Furthermore, nanoceria markedly mitigated the total intracellular superoxide flux in the macrophages. These data suggest that nanoceria could readily cross the plasma membrane and enter the mitochondrial compartment, reducing intracellular superoxide fluxes in unstimulated macrophages. In macrophages undergoing respiratory burst, nanoceria also strongly reduced superoxide flux from the activated macrophage plasma membrane NADPH oxidase (NOX) in a concentration-dependent manner. Token together, the results of the present study demonstrate that nanoceria can effectively diminish superoxide fluxes from both METC and NOX in human macrophages, which may have important implications for nanoceria-mediated protection against inflammatory disease processes.

Antiapoptotic and antioxidative effects of cerium oxide nanoparticles on the testicular tissues of streptozotocin-induced diabetic rats: An experimental study

Background

Cerium dioxide nanoparticles (CNPs) due to the antidiabetic and antioxidant activities are proposed for the treatment of oxidative stress-associated diseases.

Objective

To examine the impact of CNPs on hyperglycemia-induced apoptosis and oxidative stress in the testis of diabetic rats.

Materials and Methods

Twenty-four male rats were divided into four groups (n = 6/each) as diabetic rats, CNPs group, diabetic + CNPs rats, and controls. The control group was fed only mouse food and water. Rats became diabetic through receiving streptozotocin (STZ) 60 mg/kg. CNPs were given to the rats at a dose of 30 mg/kg daily for 2 wk. Malondialdehyde and total thiol group (TTG) levels were measured using spectrofluorometer. Expression of b-cell lymphoma protein 2-associated X protein (BAX) and b-cell lymphoma protein 2 (Bcl-2) were investigated using quantitative real-time polymerase chain reaction. Western blot analysis was used to examine caspase 3 protein levels.

Results

The content of malondialdehyde significantly increased in the STZ-diabetic rats, while TTG levels demonstrated a remarkable decrease. Caspase-3, BAX, and BAX/Bcl-2 mRNA ratio raised significantly in the STZ-diabetic rats. On the other hand, Bcl-2 mRNA levels reduced in the testis of diabetic rats (p = 0.006). Intervention with CNPs caused a substantial increase in the TTG levels, while the malondialdehyde contents, caspase-3, BAX levels, as well as BAX/Bcl-2 mRNA ratio were considerably decreased following CNPs treatment. Administration of CNPs increased mRNA levels of Bcl-2 (p < 0.0001).

Conclusion

CNPs treatment attenuates testicular apoptosis and oxidative stress induced by diabetes. This nanoparticle might be suggested for the treatment of diabetes-associated reproductive disorders.

The crucial role of heavy metals on the interaction of engineered nanoparticles with polystyrene microplastics

Despite continuous research on microplastics (MPs), studies exploring the complexity of interaction between MPs and other aqueous constituents in multi-solute systems are scarce. In this study, the uptake and release of nanoceria (CeNPs) by various polystyrene MPs (PSMPs) were investigated. Results showed that PSMPs in the presence of heavy metals (HMs) exhibited a substantially higher sorption affinity for isotropic charged CeNPs than PSMPs alone; this enhanced affinity was attributed to the formation of PSMP-HM-CeNP complexes. FE-SEM imaging reaffirmed that CeNP clusters adhered to PSMP surfaces in the presence of HMs. Such attachment varied dependent on valence state, atomic size of coexisting metal cations, surface texture, and functionalities of MPs. The HM-mediated complex formation on PSMP particles was suppressed at higher ionic strength because of competitive sorption and double-layer compression. Subsequent release of MP-adhered CeNPs and HMs varied significantly between aquatic media and various simulated digestive fluids, verifying the crucial role of MPs for transfer of engineered nanoparticles (ENPs) from natural environments into biota via ingestion of MPs and trophic transfer. Our results highlight the enhanced potential for MPs to accumulate and to transport ENPs when metallic contaminants are present, which adds to the current understanding of the environmental fate and adverse effects of MPs along with various waterborne contaminants in actual environments.

Cerium oxide nanoparticles improve cotton salt tolerance by enabling better ability to maintain cytosolic K+/Na+ ratio

Background

Salinity is a worldwide factor limiting the agricultural production. Cotton is an important cash crop; however, its yield and product quality are negatively affected by soil salinity. Use of nanomaterials such as cerium oxide nanoparticles (nanoceria) to improve plant tolerance to stress conditions, e.g. salinity, is an emerged approach in agricultural production. Nevertheless, to date, our knowledge about the role of nanoceria in cotton salt response and the behind mechanisms is still rare.

Results

We found that PNC (poly acrylic acid coated nanoceria) helped to improve cotton tolerance to salinity, showing better phenotypic performance, higher chlorophyll content (up to 68% increase) and biomass (up to 38% increase), and better photosynthetic performance such as carbon assimilation rate (up to 144% increase) in PNC treated cotton plants than the NNP (non-nanoparticle control) group. Under salinity stress, in consistent to the results of the enhanced activities of antioxidant enzymes, PNC treated cotton plants showed significant lower MDA (malondialdehyde, up to 44% decrease) content and reactive oxygen species (ROS) level such as hydrogen peroxide (H₂O₂, up to 79% decrease) than the NNP control group, both in the first and second true leaves. Further experiments showed that under salinity stress, PNC treated cotton plants had significant higher cytosolic K⁺ (up to 84% increase) and lower cytosolic Na⁺ (up to 77% decrease) fluorescent intensity in both the first and second true leaves than the NNP control group. This is further confirmed by the leaf ion content analysis, showed that PNC treated cotton plants maintained significant higher leaf K⁺ (up to 84% increase) and lower leaf Na⁺ content (up to 63% decrease), and thus the higher K⁺/Na⁺ ratio than the NNP control plants under salinity stress. Whereas no significant increase of mesophyll cell vacuolar Na⁺ intensity was observed in PNC treated plants than the NNP control under salinity stress, suggesting that the enhanced leaf K⁺ retention and leaf Na⁺ exclusion, but not leaf vacuolar Na⁺ sequestration are the main mechanisms behind PNC improved cotton salt tolerance. qPCR results showed that under salinity stress, the modulation of HKT1 but not SOS1 refers more to the PNC improved cotton leaf Na⁺ exclusion than the NNP control.

Conclusions

PNC enhanced leaf K⁺ retention and Na⁺ exclusion, but not vacuolar Na⁺ sequestration to enable better maintained cytosolic K⁺/Na⁺ homeostasis and thus to improve cotton salt tolerance. Our results add more knowledge for better understanding the complexity of plant-nanoceria interaction in terms of nano-enabled plant stress tolerance.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00892-7.

Antioxidant and C5a-blocking strategy for hepatic ischemia-reperfusion injury repair

BACKGROUND

Nonspecific liver uptake of nanomaterials after intravenous injection has hindered nanomedicine for clinical translation. However, nanomaterials' propensity for liver distribution might enable their use in hepatic ischemia-reperfusion injury (IRI) repair. During hepatic IRI, reactive oxygen species (ROS) are generated and the fifth component of complement (C5a) is activated. In addition, C5a is confirmed to exacerbate the vicious cycle of oxidative stress and inflammatory damage. For these reasons, we have investigated the development of nanomaterials with liver uptake to scavenge ROS and block C5a for hepatic IRI repair.

RESULTS

To achieve this goal, a traditional nanoantioxidant of nanoceria was surface conjugated with the anti-C5a aptamers (Ceria@Apt) to scavenge the ROS and reduce C5a-mediated inflammation. High uptake of Ceria@Apt in the liver was confirmed by preclinical positron emission tomography (PET) imaging. The clinical symptoms of hepatic IRI were effectively alleviated by Ceria@Apt with ROS scavenging and C5a blocking in mice model. The released pro-inflammatory cytokines were significantly reduced, and subsequent inflammatory reaction involved in the liver was inhibited.

CONCLUSIONS

The synthesized Ceria@Apt has great potential of medical application in hepatic IRI repair, which could also be applied for other ischemic-related diseases.

Effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria: Soot-ceria contact and interfacial oxygen evolution

Ceria is widely used as a catalyst for soot combustion, but effects of Zr substitution on the reaction mechanism is ambiguous. The present work elucidates effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria. The nanostructured CeO₂, Ce_0.92Zr_0.08O₂, and Ce_0.84Zr_0.16O₂ composed of 5-6 nm crystallites display T_m-CO2 (the temperature at maximum CO₂ yield) at 383, 355, and 375°C under 10 vol.% O₂/N₂, respectively. The size of agglomerate decreases from 165.5 to 51.9-57.3 nm, which is beneficial for the soot-ceria contact. Moreover, Zr increases the amount of surface oxygen vacancies, generating more active oxygen (O₂^- and O^-) for soot oxidation. Thus, the activities of Ce_0.92Zr_0.08O₂ and Ce_0.84Zr_0.16O₂ in soot combustion are better than that of CeO₂. Although oxygen vacancies promote the migration of lattice O^2-, the enriched surface Zr also inhibits the mobility of lattice O^2-. Therefore, the T_m-CO2 of Ce_0.84Zr_0.16O₂ is higher than that of Ce_0.92Zr_0.08O₂. Based on reaction kinetic study, soot in direct contact with ceria preferentially decomposes with low activation energy, while the oxidation of isolated soot occurs through diffusion with high activation energy. The obtained findings provide new understanding on the soot combustion over nanoceria.

Nanoceria provides antioxidant and osteogenic properties to mesoporous silica nanoparticles for osteoporosis treatment

Osteoporosis, a chronic metabolic bone disease, is the most common cause of fractures. Drugs for treating osteoporosis generally inhibit osteoclast (OC) activity, but are rarely aimed at encouraging new bone growth and often cause severe systemic side effects. Reactive oxygen species (ROS) are one of the key triggers of osteoporosis, by inducing osteoblast (OB) and osteocyte apoptosis and promoting osteoclastogenesis. Here we tested the capability of the ROS-scavenger nanoceria encapsulated within mesoporous silica nanoparticles (Ce@MSNs) to treat osteoporosis using a pre-osteoblast MC3T3-E1 cell monoculture in stressed and normal conditions. Ce@MSNs (diameter of 80 ± 10 nm) were synthesised following a scalable two-step process involving sol-gel and wet impregnation methods. The Ce@MSNs at concentration of 100 μg mL^-1 induced a significant reduction in oxidative stress produced by t-butyl hydroperoxide and did not alter cell viability significantly. Confocal microscopy showed that MSNs and Ce@MsNs were internalised into the cytoplasm of the pre-osteoblasts after 24 h but were not in the nucleus, avoiding any DNA and RNA modifications. Ce@MSNs provoked mineralisation of the pre-osteoablasts without osteogenic supplements, which did not occur when the cells were exposed to MSN without nanoceria. In a co-culture system of MC3T3-E1 and RAW264.7 macrophages, the Ce@MSNs exhibited antioxidant capability and stimulated cell proliferation and osteogenic responses without adding osteogenic supplements to the culture. The work brings forward an effective platform based for facile synthesis of Ce@MSNs to interact with both OBs and OCs for treatment of osteoporosis.

Nanoceria as a possible agent for the management of COVID-19

The COVID-19 pandemic has emerged as an unprecedented global healthcare emergency and has devastated the global economy. The SARS-CoV-2 virus replicates in the host cells and is seemingly much more virulent compared to other flu viruses, as well as the SARS-CoV-1. The respiratory complications of the disease include acute respiratory distress syndrome (ARDS), cytokine storm, systemic inflammation, and pulmonary fibrosis. Nanoceria (NC) is a versatile rare earth nanoparticle with remarkable catalase and superoxide dismutase mimetic redox regenerative properties. Interestingly, NC possesses promising anti-inflammatory, antioxidant and anti-fibrotic properties, making it an attractive tool to fight against the SARS-CoV-2 as well as the associated systemic complications. Until now, there is no clinically approved vaccine or drug for the treatment of COVID-19, and the conquest to find a novel therapy for this global havoc is being undertaken at a warlike pace. Herein, based on preclinical evidence, we hypothesize that NC owing to its unique pharmacological properties, might be an attractive preclinical candidate to win the battle over COVID-19. Further, it may be used as a prevention or treatment strategy in combination with other drugs.

Nanoceria: Metabolic interactions and delivery through PLGA-encapsulation

Cerium oxide nanoparticles (nanoceria) have recyclable antioxidative activity. It has numerous potential applications in biomedical engineering, such as mitigating damage from burns, radiation, and bacterial infection. This mitigating activity is analogous to that property of metabolic enzymes such as superoxide dismutase (SOD) and catalase - scavengers of reactive oxygen species (ROS). Therefore, nanoceria can protect cells from environmental oxidative stress. This therapeutic effect prompted studies of nanoceria and metabolic enzymes as a combination therapy. The activity and structure of SOD, catalase, and lysozyme were examined in the presence of nanoceria. A complementary relationship between SOD and nanoceria motivated the present work, in which we explored a method for simultaneous delivery of SOD and nanoceria. The biocompatibility and tunable degradation of poly(lactic-co-glycolic acid) (PLGA) made it a candidate material for encapsulating both nanoceria and SOD. Cellular uptake studies were conducted along with a cytotoxicity assay. The antioxidative properties of PLGA-nanoceria-SOD particles were verified by adding H₂O₂ to cell culture and imaging with fluorescent markers of oxidative stress. Our results suggest that PLGA is a suitable encapsulating carrier for simultaneous delivering nanoceria and SOD together, and that this combination effectively reduces oxidative stress in vitro.

Cerium oxide nanoparticles reduce the accumulation of autofluorescent deposits in light-induced retinal degeneration: Insights for age-related macular degeneration

Accumulation of lipofuscin deposits in the retinal pigment epithelium (RPE) is one of the main events involved in age-related macular degeneration and its increase together with RPE dysfunction, blood retinal barrier disruption and photoreceptors death progressively leads to blindness. Lipofuscin is the main autofluorescent (AF) component of the retina and therapies to counteract its deposition are a main goal to be achieved, since effective treatments have not yet been identified. Here, we first investigated the spatio-temporal pattern of AF deposits accumulation in the light-damage model of age-related macular degeneration. Afterward, we tested the ability of cerium oxide nanoparticles, a well known anti-oxidant agent, to counteract AF granules accumulation. The treatment was performed both before and after the induction of the degeneration. AF granules were quantified by confocal microscopy on whole mounted retinas. We demonstrated that the acute light-damage increases the accumulation of AF deposits in the hot spot retina in terms of number of granules and percentage of occupied area, with a peak 7 days after the exposure. Remarkably, cerium oxide nanoparticles showed a strong efficacy in preventing the formation of AF deposits when they were injected 3 days before light exposure. Moreover, when the treatment was performed 7 days after light exposure, nanoceria activity was found to be effective also in reducing the amount of the AF granules still deposited up to 60 days. These important results represent the very first evidence about the ability of cerium oxide nanoparticles to counteract AF deposits accumulation in retinal degeneration, laying the foundations for the development of a new therapy possibly targeting lipofuscin in AMD.

Plasma and Serum Proteins Bound to Nanoceria: Insights into Pathways by which Nanoceria may Exert Its Beneficial and Deleterious Effects In Vivo

Nanoceria (CeO₂, cerium oxide nanoparticles) is proposed as a therapeutic for multiple disorders. In blood, nanoceria becomes protein-coated, changing its surface properties to yield a different presentation to cells. There is little information on the interaction of nanoceria with blood proteins. The current study is the first to report the proteomics identification of plasma and serum proteins adsorbed to nanoceria. The results identify a number of plasma and serum proteins interacting with nanoceria, proteins whose normal activities regulate numerous cell functions: antioxidant/detoxification, energy regulation, lipoproteins, signaling, complement, immune function, coagulation, iron homeostasis, proteolysis, inflammation, protein folding, protease inhibition, adhesion, protein/RNA degradation, and hormonal. The principal implications of this study are: 1) The protein corona may positively or negatively affect nanoceria cellular uptake, subsequent organ bioprocessing, and effects; and 2) Nanoceria adsorption may alter protein structure and function, including pro- and inflammatory effects. Consequently, prior to their use as therapeutic agents, better understanding of the effects of nanoceria protein coating is warranted.

Uptake, translocation and impact of green synthesized nanoceria on growth and antioxidant enzymes activity of Solanum lycopersicum L

Cerium oxide nanoparticles (nanoceria) were synthesized by a novel, simple green chemistry procedure using Elaeagnus angustifolia leaf extract as a reducing and capping agent. The crystalline nature of nanoceria was confirmed by XRD analysis. FTIR analysis revealed that phytochemicals are present on the surface of nanoceria. SEM and TEM images revealed that the nanoceria are well dispersed, spherical in shape with a particle size range in between 30 and 75 nm. Thereafter, the effects of various concentrations of cerium oxide (CeO₂) and green synthesized nanoceria on growth and metabolism of Solanum lycopersicum (tomato) were investigated. The bio-accumulation of Ce in tomato seedlings was found to be dose dependent and the results showed that with the increase in exposure concentrations, the accumulation of Ce contents in both root and shoots augmented. However, unlike nanoceria treated seedlings, Ce contents in the roots with CeO₂ treatments were negligible than that in the shoots at lower concentrations and this suggested the immobilization of Ce in CeO₂ treatment at lower concentrations. Nanoceria at 500 and 1000 mg/L resulted in inhibitory effect on growth of test plant as compared to CeO₂ component. The exposure of plants to nanoceria and CeO₂ has resulted in significant reduction in pigment content, increased LP, EL and H₂O₂ content. The activities of antioxidant enzymes viz. SOD, CAT, APX and GPX were significantly up regulated on exposure of nanoceria and CeO₂. It is concluded that plant exposure with nanoceria at concentrations of 20 and 100 mg/L were more beneficial for growth and metabolism of tomato plants than that of CeO₂ at equivalent concentrations.

Can tailored nanoceria act as a prebiotic? Report on improved lipid profile and gut microbiota in obese mice

Background

Microbiome modulation is a pillar intervention to treat metabolic syndrome, prestages, and cascade of related pathologies such as atherosclerosis, among others. Lactobacillus and Bifidobacterium probiotic strains demonstrate efficacy to reduce obesity, dyslipidemia, and improve metabolic health. Novel prebiotic substances composed with known probiotics may strongly synergize health benefits to the host. The aim of this study was to evaluate beneficial effects of Lactobacillus and Bifidobacterium strains (probiotics) if composed with nanoceria (potential prebiotic) to reduce cholesterol levels and restore gut microbiota in obese mice.

Materials and Methods

Two lines of mice were used in the study: BALB/c mice (6-8 weeks, 18-24 g) and CBA mice (11-12 months, 20-26 g); experimental animals were fed by fat-enriched diet 3 weeks before the evaluation. Animals were divided into groups to test probiotic strains and nanoceria. All groups received probiotic strains orally and cerium dioxide orally or intravenously in various composition. A group of untreated animals was used as a control. Cholesterol level and gut microbiota of mice were studied.

Results

Cerium dioxide nanoparticles, probiotic strain L. casei ІМV В-7280, and composition B. animalis VKB/B. animalis VKL applied separately and in different combinations all reduced at different levels free and bound cholesterol in blood serum of mice fed by fat-enriched diet. The combination of 0.01 M nanoceria and probiotic strain L. casei ІМV В-7280 resulted in the fastest cholesterol level decrease in both young and mature animals. Oral administration of CeO₂ applied alone reduced the number of microscopic fungi in the gut of mice and Gram-positive cocci (staphylococci and/or streptococci). Application of L. casei IMV B-7280 as a probiotic strain increased most significantly the number of lactobacilli and bifidobacteria in the gut of mice. The most significant normalization of gut microbiota was observed after oral administration of alternatively either L. casei IMV B-7280 + 0.1 M CeO₂ or L. casei IMV B-7280 + 0.01 M CeO₂.

Conclusion

Dietary application of nanoceria combined with probiotic strains L. casei IMV B-7280, B. animalis VKB, and B. animals VKL has significantly reduced both free and bound cholesterol levels in serum. Simultaneous administration of probiotics and cerium nanoparticles as a prebiotic, in various combinations, significantly enhanced positive individual effects of them on the gut microbiota spectrum. The presented results provide novel insights into mechanisms behind nutritional supplements and open new perspectives for application of probiotics combined with substances demonstrating prebiotic qualities benefiting, therefore, the host health. Follow-up translational measures are discussed to bring new knowledge from lab to the patient. If validated in a large-scale clinical study, this approach might be instrumental for primary and secondary prevention in obese individual and patients diagnosed with diabetes. To this end, individualized prediction and treatments tailored to the person are strongly recommended to benefit the health condition of affected individuals.

Simulated biological fluid exposure changes nanoceria's surface properties but not its biological response

Nanoscale cerium dioxide (nanoceria) has industrial applications, capitalizing on its catalytic, abrasive, and energy storage properties. It auto-catalytically cycles between Ce³⁺ and Ce⁴⁺, giving it pro-and anti-oxidative properties. The latter mediates beneficial effects in models of diseases that have oxidative stress/inflammation components. Engineered nanoparticles become coated after body fluid exposure, creating a corona, which can greatly influence their fate and effects. Very little has been reported about nanoceria surface changes and biological effects after pulmonary or gastrointestinal fluid exposure. The study objective was to address the hypothesis that simulated biological fluid (SBF) exposure changes nanoceria's surface properties and biological activity. This was investigated by measuring the physicochemical properties of nanoceria with a citric acid coating (size; morphology; crystal structure; surface elemental composition, charge, and functional groups; and weight) before and after exposure to simulated lung, gastric, and intestinal fluids. SBF-exposed nanoceria biological effect was assessed as A549 or Caco-2 cell resazurin metabolism and mitochondrial oxygen consumption rate. SBF exposure resulted in loss or overcoating of nanoceria's surface citrate, greater nanoceria agglomeration, deposition of some SBF components on nanoceria's surface, and small changes in its zeta potential. The engineered nanoceria and SBF-exposed nanoceria produced no statistically significant changes in cell viability or cellular oxygen consumption rates.

Synthesis and biomedical applications of nanoceria, a redox active nanoparticle

Background

Nanoceria has recently received much attention, because of its widespread biomedical applications, including antibacterial, antioxidant and anticancer activity, drug/gene delivery systems, anti-diabetic property, and tissue engineering.

Main body

Nanoceria exhibits excellent antibacterial activity against both Gram-positive and Gram-negative bacteria via the generation of reactive oxygen species (ROS). In healthy cells, it acts as an antioxidant by scavenging ROS (at physiological pH). Thus, it protects them, while in cancer cells (under low pH environment) it acts as pro-oxidant by generating ROS and kills them. Nanoceria has also been effectively used as a carrier for targeted drug and gene delivery in vitro and in vivo models. Besides, nanoceria can also act as an antidiabetic agent and confer protection towards diabetes-associated organ pathophysiology via decreasing the ROS level in diabetic subjects. Nanoceria also possesses excellent potential in the field of tissue engineering. In this review, firstly, we have discussed the different methods used for the synthesis of nanoceria as these are very important to control the size, shape and Ce³⁺/Ce⁴⁺ ratio of the particles upon which the physical, chemical, and biological properties depend. Secondly, we have extensively reviewed the different biomedical applications of nanoceria with probable mechanisms based on the literature reports.

Conclusion

The outcome of this review will improve the understanding about the different synthetic procedures and biomedical applications of nanoceria, which should, in turn, lead to the design of novel clinical interventions associated with various health disorders.

Graphical abstract

Porous carbon supported nanoceria derived from one step in situ pyrolysis of Jerusalem artichoke stalk for functionalization of solution-gated graphene transistors for real-time detection of lactic acid from cancer cell metabolism

Effective detection of biomarkers for tumor cells has been the focus of attention. In this work, we have successfully fabricated a highly sensitive sensor based on solution-gated graphene transistors (SGGT) for detecting lactic acid content accumulated in tumor cells through their glycolysis metabolism. The sensing mechanism of the lactic acid sensor is attributed to electrochemical catalysis of H₂O₂ produced by the oxidation of lactic acid by lactate oxidase near the gate electrode. The key component of the sensor is the functionalization of porous carbon loaded with ceria nanoparticles derived from a novel one step in situ pyrolysis of pretreated Jerusalem artichoke stalk, which significantly improved the sensor sensitivity, i.e. a detection limit as low as 300 nM and linear range from 3 μM to 300 μM. The optimized lactic acid sensor has successfully applied to the detection of lactic acid in practical cell culture samples with high credibility. The SGGT-based lactic acid biosensor shows great potential for the application in tumor microenvironment due to its superior biocompatibility and accuracy.

Protective Effect of Nanoceria on Cisplatin-Induced Nephrotoxicity by Amelioration of Oxidative Stress and Pro-inflammatory Mechanisms

Cisplatin (CP) is one of the most important anticancer compounds with its therapeutic usefulness in diverse types of solid cancer. However, its use is limited due to nephrotoxicity induced by it. Oxidative stress is an effective participant which contributes actively to pathogenesis of CP-induced nephrotoxicity. Nanoparticle form of a rare earth metal cerium, also known as nanoceria (NC), has come up as a potential antioxidant and anti-inflammatory agent. In the present study, administration of CP in Swiss mice resulted in reduction of body weight, increased oxidative stress and pro-inflammatory cytokine levels including IL-6 and TNF-α along with alteration in normal histological architecture of kidney. On the contrary, NC (0.2 and 2 mg/kg i.p.) ameliorated nephrotoxicity of CP which was evident by reduction in levels of renal injury markers in plasma, i.e., creatinine and blood urea nitrogen. NC ameliorated oxidative stress by showing a reduction in levels of malondialdehyde and increased levels of endogenous antioxidants reduced glutathione and catalase. Further, NC treatment also reduced the levels of pro-inflammatory cytokines. Furthermore, protective effect of NC was also corroborated by histopathological studies wherein, kidneys from CP group showed altered tissue structure after acute as well as chronic exposure of CP while the tissues from treated groups showed absence of alterations in kidney histology. The results from present study suggested that oxidative stress and pro-inflammatory cytokines play a central role in pathogenesis of CP-induced nephrotoxicity and NC provides protection from CP-induced nephrotoxicity due to its antioxidant and anti-inflammatory properties.

Retinal long term neuroprotection by Cerium Oxide nanoparticles after an acute damage induced by high intensity light exposure

Cerium Oxide nanoparticles are antioxidant agents with autoregenerative radical scavenging activities, effective in preventing degeneration of photoreceptors of an albino rat when intravitreally injected prior to exposure to high intensity light. In this study, we performed a post injury administration of nanoceria and a long term analysis of their neuroprotective properties in order to better simulate the therapeutic treatment as it is carried out on patients with age related macular degeneration, and while photoreceptor degeneration is ongoing. We also injected nanoceria labelled with fluorescein isothiocianate in order to analyze their persistence after a single administration in a damaged retina and to investigate how long they both maintain their neuroprotective properties and where they localize in the retina. We demonstrated that after a single intravitreal injection, nanoceria remained in the retina for a long time and retained their neuroprotective properties. All these data form excellent bases for future clinical applications.

Developing Nanoceria-Based pH-Dependent Cancer-Directed Drug Delivery System for Retinoblastoma

Development of a single combinatorial nano-platform technology to target cancer cells has been an unprecedented reality in boosting synergistic anti-tumor activities and in reducing off-target effects. We have designed a novel anti-tumor delivery system using a chemotherapy drug and a tumor target molecule covalently linked to cerium oxide nanoparticles (nanoceria). Nanoceria have a unique redox activity in that they possess antioxidant activity at physiological pH but have an intrinsic oxidase activity at acidic pH. Our system is integrated with (1) extracellular pH responsive functionality, (2) tumor cell targetable (CXC chemokine receptor 4, CXCR4 receptor specific) antagonist, (3) reactive oxygen species (ROS) inducible nanoceria, and (4) chemotherapeutic doxorubicin (DOX). These combinatorial nanoparticles (AMD-GCCNPs-DOX) are not only sensitive to the extracellular acidic pH conditions and targeted tumor cells but can also instantaneously induce ROS and release DOX intracellularly to enhance the chemotherapeutic activity in retinoblastoma cells (WERI-Rb-1 and Y79) and in xenograft (Y79/GFP-luc grafted) and genetic p107s (Rb Lox/lox , p107 +/- , p130 -/- ) orthotopic mice models. Together we introduce a lucidly engineered combinatorial nano-construct that offers a viable and simple strategy for delivering a cocktail of therapeutics into tumor cells under acidosis, exhibiting a promising new future for clinical therapeutic opportunities.

Cardioprotective effects of nanoceria in a murine model of cardiac remodeling

Isoproterenol (ISO), a synthetic β₁ adrenergic agonist is a well-known agent to be associated with severe cardiotoxicity manifested as marked myocardial necrosis and fibrosis. Oxidative stress plays a crucial role in mediating ISO induced cardiotoxicity. In present study, we have investigated the possible protective effect of nanoceria (NC) in ISO induced cardiac injury. We have given long duration exposure (a total of 10 days) of low dose ISO (20 mg/kg/day) to investigate the protective effects of NC in chronic cardiac injury model. ISO (20 mg/kg/day for 10 days) produced cardiac injury as evident by increased plasma LDH and CK-MB, AST, ALT, cardiac hypertrophy, severe myocardial fibrosis (MF) and significantly higher levels of cytokines, IL-6, TGF-β and TNF-α. Interestingly, the treatment with NC (0.2 and 2 mg/kg) abrogated cardiotoxicity symptoms and provided protection from ISO induced cardiac injury. The results from present study demonstrated strong evidences of cardioprotective effects of NC as shown by reduction in the levels of LDH (p < 0.05 at 2 mg/kg) and CK-MB (p < 0.05 at 2 mg/kg). In addition, NC reduced oxidative stress parameters MDA (p < 0.05 at 2 mg/kg) and enhanced GSH levels which is physiological antioxidant (p < 0.01 at both doses). Further, NC exhibited promising anti-inflammatory activity and curbed the levels of cytokines (p < 0.05 at 0.2 mg/kg and p < 0.001 for IL-1β and p < 0.001 at both doses for IL-6). In addition, NC also reduced the levels of pro-fibrotic cytokine, TGF-β (p < 0.05 at 2 mg/kg) and helped in reduction of collagen deposition in heart thereby, preventing the myocardial remodeling. Our results strongly suggested that NC might be of potential use as a cardioprotective agent.

Nanoceria ameliorates doxorubicin induced cardiotoxicity: Possible mitigation via reduction of oxidative stress and inflammation

Doxorubicin (DOX) is one of the most commonly used anticancer drugs but its use has been limited due to constraints of cardiotoxic side effects. The precise mechanism underlying cardiotoxicity is not yet fully understood but oxidative stress has been found to be a primary mechanism behind this. In addition, DOX induced cardiotoxicity also shows involvement of proinflammatory cytokines such as IL-6 and TNF-α. Since oxidative stress plays major role in DOX induced cardiotoxicity, different antioxidants have been tried to prevent cardiotoxicity of DOX. Nanoparticles have risen up as a promising material with a wide variety of actions, and cerium oxide nanoparticles or nanoceria (NC) is one of such kind with great antioxidant potential. NC has emerged as a promising antioxidant in different pathological conditions. The present study was aimed to investigate possible protective effects of NC in DOX induced cardiotoxicity. Cardiotoxicity was induced in Swiss mice by DOX administration through i.p. route at a dose level of 15 mg/kg in two divided doses on alternate days. In our study, NC was found to mitigate cardiotoxic potential of DOX and prevented weight loss. NC restored the levels of cardiac injury markers lactate dehydrogenase (LDH) and creatinine kinase MB (CK-MB). Moreover, NC reduced malondialdehyde (MDA) levels and increased endogenous antioxidants such as reduced glutathione (GSH) and catalase levels. In addition, NC decreased proinflammatory cytokine levels and also prevented the alteration in normal structure of heart samples. Our study showed protective effects of NC in DOX induced cardiotoxicity which can become a potential therapeutic intervention against DOX induced cardiotoxicity.

Decreased Uptake and Enhanced Mitochondrial Protection Underlie Reduced Toxicity of Nanoceria in Human Monocyte-Derived Macrophages

Cerium dioxide nanoparticles (nanoceria), currently used as catalysts including additives to diesel fuel, also present potential as a novel therapeutic agent for disorders involving oxidative stress. However, little is known about the effects of nanoceria on primary human cells involved in the innate immune response. Here, we evaluate nanoceria effects on monocyte derived macrophages (MDMs) from healthy human subjects. Peripheral blood monocytes were isolated from healthy human volunteers. MDMs were obtained by maturing monocytes over a five-day period. MDMs were exposed to well-characterized nanoceria suspensions (0, 5, 10, 20 μg/mL) for 24 or 48 hours. We evaluated particle uptake, ultrastructural changes, cytotoxicity, and mitochondrial damage in MDMs through transmission electron microscopy (TEM), confocal imaging, flow cytometry, spectrometry, western blots, and immunofluorescence techniques. The role that intracellular concentration of nanoceria plays in the toxicity of MDMs was evaluated by 3D image analysis and compared to monocytes as a nanoceria sensitive cell model. Nanoceria failed to induce cytotoxicity in MDMs at the tested doses. Nanoceria-exposed MDMs showed no mitochondrial damage and displayed significant accumulation of anti-apoptotic proteins (Mcl-1 and Bcl-2) during the maturation process. TEM and confocal analyses revealed efficient uptake of nanoceria by MDMs, however 3D image analyses revealed lower nanoceria accumulation per unit cell volume in MDMs compared to monocytes. Taken together, our results suggest that mitochondrial protection and reduced volume-corrected intracellular nanoparticle concentration account for the lower sensitivity of human MDMs to nanoceria.

A novel cerium oxide nanoparticles-based colorimetric sensor using tetramethyl benzidine reagent for antioxidant activity assay

Antioxidant activity (AOA) assays using nanotechnology are recently developed utilizing nanoparticles of transition metal oxides, especially nanoceria that can switch between trivalent and tetravalent oxidation states of cerium. Cerium oxide nanoparticles (CeO-NPs) may act as both an oxidant and an antioxidant, depending on the preparation method and particle size. A novel colorimetric sensor for AOA assay is proposed with the use of poly(acrylic acid) sodium salt (PAANa)-coated CeO-NPs. PAANa-coated CeO-NPs oxidized tetramethyl benzidine (TMB), a peroxidase substrate, in a slightly acidic solution at pH 4.0 to a blue charge-transfer complex. Antioxidants decreased the color intensity of the nanoceria suspension, and were indirectly determined by absorbance difference. Detection limits, linearity, additivity and precision were calculated, e.g., quercetin quantification with the proposed assay showed a detection limit of 8.25 × 10^-9 mol L^-1. The trolox equivalent antioxidant capacities of hydrophilic and lipophilic antioxidants were compatible with those of conventional antioxidant assays. Potential interferents such as glucose, citric acid, mannitol, sorbitol and benzoic acid did not adversely affect AOA determination. The developed sensor is more sensitive and selective than similar colorimetric sensors relying on the intrinsic color change of nanoceria. The measurement wavelength is sufficiently red-shifted, preventing possible interferences from plant pigments.

Embryo-Protective Effects of Cerium Oxide Nanoparticles against Gestational Diabetes in Mice

Gestational diabetes is defined as carbohydrate intolerance with onset or first recognition during pregnancy. Diabetes during pregnancy increases the incidences of congenital anomalies, in a mother and her embryo. Oxidative stress has been implicated to be responsible in diabetic embryopathy. In this study, we used nanoceria as an antioxidant for amelioration of diabetic embryopathy in diabetic mice. The female mice were divided into 5 groups (6 mice per group). Diabetes was induced by a single dose of streptozotocin (60 mg/kg IP) that dissolved in citrate buffer (pH = 4.6). Blood glucose was checked in 0,5,10, and 15 days of pregnancy. The diabetic state was confirmed when the blood glucose concentration exceeded 200 mg/dL. On the day 16 of pregnancy, all animals were anesthetized with ether and embryos were excised; then oxidative stress, pathological parameters, number of implantations, miscarriage, and live embryo were assayed. Histological study showed that diabetes induced abortion; decrease in weight of mothers, embryo, and the number of embryos were observed. In diabetic mice, significant increase in lipid peroxidation (LPO), ROS formation, and protein carbonyl content were observed. Glutathione (GSH) concentration is found to be decreased in embryo tissue in diabetic mice. Nanoceria treatment significantly inhibited embryonic oxidative stress and also pathologic changes in diabetic mice. Our research showed that diabetes act as a teratogen agent for fetal development and nanoceria abrogated diabetes induced embryopathy via its antioxidant effects. So, early detection of diabetes in pregnancy and antioxidant administration can attenuate these complications.

A fluorescent "on-off-on" probe for sensitive detection of ATP based on ATP displacing DNA from nanoceria

A simple, rapid, and ultrasensitive fluorescence strategy for adenosine triphosphate (ATP) detection was developed by using a FAM (carboxyfluorescein) labeled DNA (FAM-DNA). In this strategy, highly fluorescent FAM-DNA was used as a probe, and nanoceria (CeO₂ NPs) acted as an efficient quencher. FAM-DNA attached to the surface of nanoceria through the coordination between the phosphate group of DNA and NP surface, which induced complete quenching in the FAM-DNA fluorescence due to a photo induced electron transfer (PET) process. It was found that ATP can readily displace adsorbed DNA from nanoceria surface because of the stronger coordination ability of ATP with nanoceria, and the nanoceria-based competitive binding resulted in over 7-fold fluorescence enhancement. Over a wide range from 0.1nM to 1.5μM, a good linear relationship between the fluorescence intensity and the concentration of ATP was obtained and the detection limit was estimated to be as low as 54pM. This method was successfully used to analyze ATP in a single drop of blood and human urine.

Shape-Specific Nanoceria Mitigate Oxidative Stress-Induced Calcification in Primary Human Valvular Interstitial Cell Culture

INTRODUCTION

Lack of effective pharmacological treatment makes valvular calcification a significant clinical problem in patients with valvular disease and bioprosthetic/mechanical valve replacement therapies. Elevated levels of reactive oxygen species (ROS) in valve tissue have been identified as a prominent hallmark and driving factor for valvular calcification. However, the therapeutic value of ROS-modulating agents for valvular calcification remains elusive. We hypothesized that ROS-modulating shape-specific cerium oxide nanoparticles (CNPs) will inhibit oxidative stress-induced valvular calcification. CNPs are a class of self-regenerative ROS-modulating agents, which can switch between Ce3+ and Ce4+ in response to oxidative microen-vironment. In this work, we developed oxidative stress-induced valve calcification model using two patient-derived stenotic valve interstitial cells (hVICs) and investigated the therapeutic effect of shape-specific CNPs to inhibit hVIC calcification.

METHODS

Human valvular interstitial cells (hVICs) were obtained from a normal healthy donor and two patients with calcified aortic valves. hVICs were characterized for their phenotypic (mesenchymal, myofibroblast and osteoblast) marker expression by qRT-PCR and antioxidant enzymes activity before and after exposure to hydrogen peroxide (H2O2)-induced oxidative stress. Four shape-specific CNPs (sphere, short rod, long rod, and cube) were synthesized via hydrothermal or ultra-sonication method and characterized for their biocompatibility in hVICs by alamarBlue® assay, and ROS scavenging ability by DCFH-DA assay. H2O2 and inorganic phosphate (Pi) were co-administrated to induce hVIC calcification in vitro as demonstrated by Alizarin Red S staining and calcium quantification. The effect of CNPs on inhibiting H2O2-induced hVIC calcification was evaluated.

RESULTS

hVICs isolated from calcified valves exhibited elevated osteoblast marker expression and decreased antioxidant enzyme activities compared to the normal hVICs. Due to the impaired antioxidant enzyme activities, acute H2O2-induced oxidative stress resulted in higher ROS levels and osteoblast marker expression in both diseased hVICs when compared to the normal hVICs. Shape-specific CNPs exhibited shape-dependent abiotic ROS scavenging ability, and excellent cytocompatibility. Rod and sphere CNPs scavenged H2O2-induced oxidative stress in hVICs in a shape- and dose-dependent manner by lowering intracellular ROS levels and osteoblast marker expression. Further, CNPs also enhanced activity of antioxidant enzymes in hVICs to combat oxidative stress. Cube CNPs were not effective ROS scavengers. The addition of H2O2 in the Pi-induced calcification model further increased calcium deposition in vitro in a time-dependent manner. Co-administration of rod CNPs with Pi and H2O2 mitigated calcification in the diseased hVICs.

CONCLUSIONS

We demonstrated that hVICs derived from calcified valves exhibited impaired antioxidant defense mechanisms and were more susceptible to oxidative stress than normal hVICs. CNPs scavenged H2O2-induced oxidative stress in hVICs in a shape-dependent manner. The intrinsic ROS scavenging ability of CNPs and their ability to induce cellular antioxidant enzyme activities may confer protection from oxidative stress-exacerbated calcification. CNPs represent promising antioxidant therapy for treating valvular calcification and deserve further investigation.

Fluorescence resonance energy transfer aptasensor between nanoceria and graphene quantum dots for the determination of ochratoxin A

In the present work, colloidal cerium oxide nanoparticles (nanoceria) and graphene quantum dots (GQDs) were firstly synthesized by sol-gel method and pyrolysis respectively, which all have a uniform nano-size and significant fluorescence emission. Due to the fluorescence emission spectrum of nanoceria overlapped the absorption spectrum of GQDs, fluorescence resonance energy transfer (FRET) between nanoceria and GQDs could occur effectively by the electrostatic interaction. Based on it, a sensitive ratiometric fluorescence aptasensor for the determination of ochratoxin A (OTA), a small molecular mycotoxin produced by Aspergillus and Penicillium strains, has been successfully constructed. In which, probe DNA1@nanoceria and DNA2@GQD were designed to complementary with OTA aptamer, both could adsorb each other, leading to the occur of FRET. After adding of OTA aptamer and then introducing of OTA, the FRET would be interrupted/recovered due to the specific affinity of OTA and its aptamer, the fluorescence recovery value would increase with the addition of OTA. Under the optimal experimental conditions (pH 7, m_{GQD/nanoceria} 2, c_aptamer 100 nM, incubation time 30 min), the constructed ratiometric fluorescence aptasensor exhibited a satisfying linear range (0.01-20 ng mL^-1), low limit of detection (2.5 pg mL^-1) and good selectivity towards OTA, and has been successfully applied for the analysis of real sample peanuts with good accuracy of the recoveries ranged from 90 to 110%.

Efficacy of nanoceria for periodontal tissues alteration in glutamate-induced obese rats-multidisciplinary considerations for personalized dentistry and prevention

BACKGROUND

Nowadays, we face the global epidemic of obesity, that is known to contribute to the development of many diseases, such as the oral cavity pathologies. Dental and oral pathologies are frequently caused by and overlapped with systemic multifactorial diseases such as obesity being its early indicators and risk factors. The aim was to study the influence of nanoceria on periodontal tissues alteration in glutamate (MSG)-induced obese rats.

METHODS

We included 52 Wistar rats of both genders and divided into four groups: newborn rats in group 1 (control) received subcutaneously 8 μl/g saline. Group 2 received 3 to 4 mg/g MSG subcutaneously on the second, fourth, sixth, eighth, and tenth day of life; group 3-intragastric administration of nanocrystalline cerium dioxide at a dose of 1 mg/kg volume of 2.9 ml/kg against the background of glutamate-induced obesity; the fourth group of animals was treated with a solution of sodium citrate intragastric volume of 2.9 ml/kg (solvent of nanocrystalline cerium). We determined the total proteolytic activity, the total antitrypsin activity, the content-free fucose and glycosaminoglycanes (GAG), content of TBA-active of products, the content of oxidation-modified proteins (OMB), and catalase activity in the homogenate of soft periodontal tissues of rats.

RESULTS

Intragastric injection of nanoceria prevents activation of proteolytic processes, reducing the catabolism of glycoproteins and proteoglycans of periodontal tissue in MSG-induced obese rats. Injection of nanoceria prevents activation of proteolytic processes, significantly decreases the total proteolytic activity, and inhibits the activation of free radical oxidation in periodontal tissues of rats compared with MSG-induced obesity model without corrections. Further, it significantly increases the total antitrypsin activity in periodontal tissues by 1.7 times, TBA-reagents by 1.7 times, and content of OMB by 1.4 times compared with glutamate-induced obese animals.

CONCLUSIONS

MSG-induced obesity triggers periodontal tissue alterations in the rat model. Nanoceria contributes to the corrections of pathological changes in periodontal tissues in glutamate-induced obese rats via balancing protein-inhibitory capacity and reducing the depolymerization of fucosylated proteins and proteoglycans and antioxidative activity.