CeO2 NP Research Articles

Cerium Oxide Nanoparticles (CeO2 NPs) Enhance Salt Tolerance in Spearmint (Mentha spicata L.) by Boosting the Antioxidant System and Increasing Essential Oil Composition

Salinity represents a considerable environmental risk, exerting deleterious effects on horticultural crops. Nanotechnology has recently emerged as a promising avenue for enhancing plant tolerance to abiotic stress. Among nanoparticles, cerium oxide nanoparticles (CeO2 NPs) have been demonstrated to mitigate certain stress effects, including salinity. In the present study, the impact of CeO2 NPs (0, 25, and 100 mg L−1) on various morphological traits, photosynthetic pigments, biochemical parameters, and the essential oil profile of spearmint plants under moderate (50 mM NaCl) and severe (100 mM NaCl) salinity stress conditions was examined. As expected, salinity reduced morphological parameters, including plant height, number of leaves, fresh and dry weight of leaves and shoots, as well as photosynthetic pigments, in comparison to control. Conversely, it led to an increase in the content of proline, total phenols, malondialdehyde (MDA), hydrogen peroxide (H2O2), and antioxidant enzyme activities. In terms of CeO2 NP applications, they improved the salinity tolerance of spearmint plants by increasing chlorophyll and carotenoid content, enhancing antioxidant enzyme activities, and lowering MDA and H2O2 levels. However, CeO2 NPs at 100 mg L−1 had adverse effects on certain physiological parameters, highlighting the need for careful consideration of the applied concentration of CeO2 NPs. Considering the response of essential oil compounds, combination of salinity stress and CeO2 treatments led to an increase in the concentrations of L-menthone, pulegone, and 1,8-cineole, which are the predominant compounds in spearmint essential oil. In summary, foliar application of CeO2 NPs strengthened the resilience of spearmint plants against salinity stress, offering new insights into the potential use of CeO2 NP treatments to enhance crop stress tolerance.

Green Synthesis, Spectroscopic, Electrochemical and Antifungal Characteristics of Ni-doped CeO2 Nanoparticles

This study intended to synthesize Nickel-doped Cerium oxide (Ni-CeO2 NPs) nanoparticles using Pedalium Murex leaf extract. X-ray diffraction (XRD) was used to investigate the structure of the Ni-CeO2 NPs. The XRD measurements showed that the Ni-CeO2 NPs crystallized into the face-centered cubic system. The Ni(1%)-CeO2 and Ni(3%)-CeO2 NP’s crystallite sizes were between 47[Formula: see text]nm and 59[Formula: see text]nm. FTIR and Raman spectral studies were conducted to investigate the sample’s atomic vibrations and chemical bonding. Energy-dispersive X-ray study and field-emission scanning electron microscopy were performed to examine the surface texture and chemical assembly of the Ni-CeO2 NPs. UV–Vis DRS spectrum study was performed to ascertain the reflectance characteristics and bandgap of Ni-CeO2 NPs. The Ni(1%)-CeO2 and Ni(3%)-CeO2 NPs were found to have bandgaps of 2.73[Formula: see text]eV and 2.82[Formula: see text]eV, respectively. Electrochemical impedance spectroscopy and cyclic voltammetry were employed to explore the electrochemical nature of Ni-CeO2 NPs and their capacitive properties at various scanning rates. Using the agar well-diffusion technique, the antifungal activities of Ni-CeO2 NPs were assessed. The experimental findings illustrate the utility of Ni-CeO2 NPs for supercapacitor electrode material and healthcare applications.

Alleviation of arsenic stress in pakchoi by foliar spraying of engineered nanomaterials.

Addressing heavy metal contamination in leafy vegetables is critically important due to its adverse effects on human health. In this study, we investigated the inhibitory effects of foliar spraying with four nanoparticles (CeO2, ZnO, SiO2, and S NPs) on arsenic (As) stress in pakchoi (Brassica rapa var. Chinensis). The findings reveal that foliar application of ZnO NPs at 1 ~ 2.5 mg plant-1 and CeO2 NPs at 5 mg plant-1 significantly reduces As in shoots by 40.9 ~ 47.3% and 39.4%, respectively. Moreover, 5 mg plant-1 CeO2 NPs increased plant height by 6.06% and chlorophyll a (Chla) content by 30.2% under As stress. Foliar spraying of CeO2 NPs at 0.2-5 mg plant-1 also significantly enhanced superoxide dismutase (SOD) activity in shoots by 9.4 ~ 13.9%, lowered H2O2 content by 42.4 ~ 53.25%, and increased root protein contents by 79 ~ 109.2%. CeO2 NPs regulate the As(III)/As(V) ratio, aiding in As efflux from roots and thereby reducing As toxicity to plants. In vitro digestion experiments reveal that the consumption of CeO2 NPs carries the lowest health risk of As. In addition, foliar spraying of ZnO NPs at 1 ~ 2.5 mg plant-1 can suppress plant As uptake by modulating enzyme activity, reducing leaf damage, and enhancing chlorophyll content. The study demonstrates that high CeO2 NP concentrations and suitable ZnO NP concentrations can alleviate As toxicity in pakchoi, consequently reducing human health risks.

Ceria nanoparticles: biomedical applications and toxicity.

Ceria nanoparticles (CeO2 NPs) have become popular materials in biomedical and industrial fields due to their potential applications in anti-oxidation, cancer therapy, photocatalytic degradation of pollutants, sensors, etc. Many methods, including gas phase, solid phase, liquid phase, and the newly proposed green synthesis method, have been reported for the synthesis of CeO2 NPs. Due to the wide application of CeO2 NPs, concerns about their adverse impacts on human health have been raised. This review covers recent studies on the biomedical applications of CeO2 NPs, including their use in the treatment of various diseases (e.‍g., Alzheimer's disease, ischemic stroke, retinal damage, chronic inflammation, and cancer). CeO2 NP toxicity is discussed in terms of the different systems of the human body (e.‍g., cytotoxicity, genotoxicity, respiratory toxicity, neurotoxicity, and hepatotoxicity). This comprehensive review covers both fundamental discoveries and exploratory progress in CeO2 NP research that may lead to practical developments in the future.

Erythrocyte-Like Mesoporous PDA@CeO2 Nanozyme with Dual Drugs for Periodontitis Treatment.

Periodontitis is a chronic oral inflammatory disease with the characteristic of excess oxidative stress in the inflammatory site, dramatically decreasing the quality of life. Studies show that nanozymes can be ideal candidates for ROS scavenging in periodontitis. Here, we design a multipath anti-inflammatory mesoporous polydopamine@cerium oxide nanobowl (mPDA@CeO2 NB) with multienzyme mimicking properties, which combines the advantages of both CeO2 NP and mPDA NB for synergistically eliminating reactive oxygen species (ROS), including hydroxyl radical (•OH), hydrogen peroxide (H2O2), and superoxide (O2•-). Besides, the erythrocyte-like structure of mNBs makes them a facility for cell uptake, and the mesopores can load both hydrophobic and hydrophilic drugs for combined anti-inflammatory therapy. In vitro and in vivo experiments prove that the combination of CeO2 and mPDA can synergistically achieve multiple complementary ROS eliminations and suppression of ROS-induced inflammation. Moreover, the ROS regulation plus anti-inflammatory drugs in one mPDA@CeO2 NB prevents the progression of periodontitis in a mouse model. Therefore, the design of mPDA@CeO2 NB with these excellent properties provides a therapeutic strategy for inflammatory diseases.

A novel electrochemical strategy to detect hydrogen peroxide by utilizing peroxidase-mimicking activity of cerium oxide/graphene oxide nanocomposites

We herein describe a novel electrochemical strategy to detect hydrogen peroxide (H2O2) by utilizing the peroxidase-mimicking activity of cerium oxide nanoparticles (CeO2 NP) and reduced graphene oxide (rGO). Particularly, CeO2 NP/rGO nanocomposites were deposited on the commercial electrode by a very convenient and direct electrochemical reduction of graphene oxide. Due to the peroxidase-mimicking activity of CeO2 NP and the outstanding electrochemical properties of reduced graphene oxide, the reduction current of H2O2 was greatly enhanced. Based on this strategy, we reliably determined H2O2 down to 1.67 μM with excellent specificity and further validated its practical capabilities by robustly detecting H2O2 present in heterogeneous human serum samples. We believe that this work could serve as a new facile platform for H2O2 detection.

Synthesis of CeO2 nanoparticles from hemp leaf Extract: Evaluation of Antibacterial, anticancer and enzymatic activities

With the development of technology, many studies continue on nanotechnological material synthesis and the development of synthesis methods. In metal/metal oxide nanoparticle synthesis, apart from classical synthesis methods such as chemical and physical, “green synthesis” represents the latest research used in nanotechnology. In this study, CeO2 metal oxide nanoparticles were synthesized from the waste leaves of Cannabis sativa L., popularly known as cannabis, using the “green synthesis” method, characterized by various methods, and research was conducted on its antibacterial, anticancer, and enzymatic effects. According to XRD result, the average crystallite size of CeO2 NPs was calculated as 52 nm due to analysis. Transmission electron microscopy (STEM) images showed that the nanoparticles had angular structures and ranged in size from 49 to 68 nm. It was informed that the nanoparticles obtained by EDX analysis had 35.66 % O and 54.56 % Ce content. The cytotoxic effect of CeO2 NP was evaluated in human breast cancer cells and human mammary epithelial cells. Accordingly, CeO2 NP had an inhibitory effect on cell proliferation, and the cytotoxic effects of CeO2 NP were higher against breast cancer cells than normal epithelial cells. The CeO2 NP has an IC50 value of 2.789 ± 0.44 mg/mL against AChE. According to antibacterial analysis, the CeO2 NP adversely affects all tested microorganisms. Especially it demonstrated bactericidal activity against E. coli at 500 µg/mL.

16 Biological Effects of Benzo-[A]-Pyrene and Cerium Nanoparticles on the Human Placental Barrier

Abstract The human placenta is a transitory organ essential for fetal development, whose functions can be disrupted by xenobiotics in maternal blood. Benzo-[a]-pyrene (B[a]P) is a carcinogenic, mutagenic and reprotoxic pollutant as well as an endocrine disruptor that can be internalized in the human body by respiratory exposure. Cerium dioxide nanoparticles (CeO2 NP) have been introduced into our environment, mainly for their catalytic properties and share the same emission sources as B[a]P (cigarette smoke and diesel engine exhaust). The aim of our study is to determine the impact of these two atmospheric pollutants on the human placenta in concomitant exposure, in order to get closer to the environmental reality. Chorionic villi and villous cytotrophoblasts (VCT) from human placentas at term of pregnancy were exposed in vitro to the pollutants. The internalization of the pollutants was observed by confocal and Raman microscopy. Cytotoxicity was assessed using WST-1 test and extracellular LDH assay. Placental endocrine activity was assessed by ELISA. The signaling pathways impacted have been studied by Western Blot, RT-qPCR and IHC. CeO2 NP and B[a]P can be internalized within the chorionic villi. B[a]P alone or in co-exposure with CeO2 NP activate the metabolic pathway of the aryl hydrocarbon receptor (AhR), causing DNA damage. B[a]P also stabilizes the stress transcription factor p53 and its transcriptional target p21. Although these two pollutants do not cause major toxicity on term human trophoblasts after in vitro exposures, cellular stress markers are induced.

Benzo(a)pyrene and Cerium Dioxide Nanoparticles in Co-Exposure Impair Human Trophoblast Cell Stress Signaling

Human placenta is a multifunctional interface between maternal and fetal blood. Studying the impact of pollutants on this organ is crucial because many xenobiotics in maternal blood can accumulate in placental cells or pass into the fetal circulation. Benzo(a)pyrene (BaP) and cerium dioxide nanoparticles (CeO2 NP), which share the same emission sources, are found in ambient air pollution and also in maternal blood. The aim of the study was to depict the main signaling pathways modulated after exposure to BaP or CeO2 NP vs. co-exposure on both chorionic villi explants and villous cytotrophoblasts isolated from human term placenta. At nontoxic doses of pollutants, BaP is bioactivated by AhR xenobiotic metabolizing enzymes, leading to DNA damage with an increase in γ-H2AX, the stabilization of stress transcription factor p53, and the induction of its target p21. These effects are reproduced in co-exposure with CeO2 NP, except for the increase in γ-H2AX, which suggests a modulation of the genotoxic effect of BaP by CeO2 NP. Moreover, CeO2 NP in individual and co-exposure lead to a decrease in Prx-SO3, suggesting an antioxidant effect. This study is the first to identify the signaling pathways modulated after co-exposure to these two pollutants, which are common in the environment.

Amplification of oxidative stress with a hyperthermia-enhanced chemodynamic process and MTH1 inhibition for sequential tumor nanocatalytic therapy.

During chemodynamic therapy (CDT), tumor cells can adapt to hydroxyl radical (˙OH) invasion by activating DNA damage repairing mechanisms such as initiating mutt homologue 1 (MTH1) to mitigate oxidation-induced DNA lesions. Therefore, a novel sequential nano-catalytic platform MCTP-FA was developed in which ultrasmall cerium oxide nanoparticle (CeO2 NP) decorated dendritic mesoporous silica NPs (DMSN NPs) were used as the core, and after encapsulation of MTH1 inhibitor TH588, folic acid-functionalized polydopamine (PDA) was coated on the periphery. Once endocytosed into the tumor, CeO2 with multivalent elements (Ce3+/4+) could transform H2O2 into highly toxic ˙OH through a Fenton-like reaction to attack DNA as well as eliminating GSH through a redox reaction to amplify oxidative damage. Meanwhile, controllable release of TH588 hindered the MTH1-mediated damage repair process, further aggravating the oxidative damage of DNA. Thanks to the excellent photothermal performance of the PDA shell in the near-infrared (NIR) region, photothermal therapy (PTT) further improved the catalytic activity of Ce3+/4+. The therapeutic strategy of combining PTT, CDT, GSH-consumption and TH588-mediated amplification of DNA damage endows MCTP-FA with powerful tumor inhibition efficacy both in vitro and in vivo.

Effects of doping Mn, Cu and Fe oxides on polyhedron CeO2 catalyst during NH3-SCR reaction

BackgroundCeria (CeO2) was considered as one of the most promising catalysts due to its oxygen storage capacity and redox property. However, the low activity of CeO2 catalyst in SCR reaction limited its further application on industrial processes. MethodsTransition metal (Mn, Cu and Fe) oxides were impregnated on nanopolyhedron CeO2 (CeO2-NP) catalysts to investigate the SCR performance. Significant findingsThe Mn-CeO2-NP catalyst displayed the highest NOx conversion (ca. 70% conversion at 300 °C), followed by the Cu-CeO2-NP catalyst (ca. 65% conversion at 300 °C) and then the Fe-CeO2-NP catalyst (ca. 45% conversion at 300 °C). The results of H2-TPR showed that Mn-CeO2-NP and Cu-CeO2-NP catalysts were more efficient in reducing hydrogen at lower temperature than that of Fe-CeO2-NP catalysts. Based on XPS measurements, it was determined that the Oα/(Oα+Oβ) ratio was Mn-CeO2-NP (ca. 65%)> Fe-CeO2-NP (ca. 59%)> Cu-CeO2-NP (ca. 55%) catalyst. It was also shown by Raman spectroscopy that the Mn-CeO2-NP catalyst had a higher concentration of oxygen vacancies than that of the Cu-CeO2-NP and Fe-CeO2-NP catalysts. Meanwhile, more Brønsted acid sites, Lewis acid sites, nitrate and nitrites species were found in the Mn-CeO2-NP catalyst as seen by in situ DRIFT spectra.

Antioxidant Activity of New Copolymer Conjugates of Methoxyoligo(Ethylene Glycol)Methacrylate and Betulin Methacrylate with Cerium Oxide Nanoparticles In Vitro.

The synthesis of two new copolymer conjugates of methoxyoligo(ethylene glycol)methacrylate MPEGMA and betulin methacrylate BM was developed via RAFT polymerization. The molar content of BM units was equal to 9–10 and 13–16 mol%, respectively (HPLC, 1H and 13C NMR); molar weights were equal to 75000–115000. CeO2 NPs as a component of the hybrid material were synthesized for the preparation of the composition with copolymer conjugates of MPEGMA and BM. We showed a significant increase in G6PDH and GR activities by 21–51% and 9–132%, respectively, which was due to the increase in NADPH concentration under the action of copolymers in vitro. The actions of copolymers and CeO2 NPs combination were stronger than those of the individual components: the SOD activity increased by more than 30%, the catalase activity increased dose-dependently from 13 to 45%, and the GR activity increased to 49%. The maximum increase in enzyme activity was observed for the G6PDH from 54% to 151%. The MDA level dose-dependently increased by 3–15% under the action of copolymers compared with the control, and dose-dependently decreased by 3–12% in samples containing CeO2 NPs only. CeO2 NP–copolymer compositions can be used for the design of new biomimetic medical products with controlled antioxidant properties.

Transient disturbance of CeO2 nanoparticles enhances N2O emissions during biological wastewater treatment

Although the negative effects of CeO2 nanoparticles (CeO2 NPs) on wastewater treatment processes have been confirmed, their impacts on the greenhouse gas nitrous oxide (N2O) emissions during biological nitrogen removal (BNR) remain unclear. Herein, the response of BNR and associated N2O emissions in a sequencing batch reactor (SBR) to different loads (1–50 mg/L) of CeO2 NPs was investigated. Although CeO2 NPs induced the dose-dependent inhibition on NH4+ oxidation rate, the NH4+-N and total nitrogen (TN) removal efficiencies did not change. The N2O emission flux was enhanced along with the increase in the CeO2 NP dose, and there was a positive correlation between N2O emission and nitrite accumulation. In addition, NH4+ oxidation activity indicators ammonia monooxygenase (AMO) activity, specific ammonia oxidation rate (SAOR), and specific oxygen uptake rate (SOUR) were suppressed under the 25 and 50 mg/L CeO2 NP stresses. The increase in reactive oxygen species (ROS) levels induced by NP stress resulted in the downregulation of the amoA and nosZ gene expression. Furthermore, the CeO2 NP shock load caused the severe suppression of NH4+ oxidizing bacteria-related Nitrosomonas activities while promoted the denitrifying glycogen-accumulating organism (potential N2O producer)-related Dechloromonas activities. In summary, this study proves evidence that the transient disturbance of CeO2 NPs would negatively affect the biological nitrogen transformation to release more N2O.

Synchrotron XRF Analysis Identifies Cerium Accumulation Colocalized with Pharyngeal Deformities in CeO2 NP-Exposed Caenorhabditis elegans.

A combination of synchrotron radiation-based elemental imaging, in vivo redox status analysis, histology, and toxic responses was used to investigate the uptake, biodistribution, and adverse effects of Ce nanoparticles (CeO2 NP; 10 nm; 0.5–34.96 mg Ce L–1) or Ce(NO3)3 (2.3–26 mg Ce L–1) in Caenorhabditis elegans. Elemental mapping of the exposed nematodes revealed Ce uptake in the alimentary canal prior to depuration. Retention of CeO2 NPs was low compared to that of Ce(NO3)3 in depurated individuals. X-ray fluorescence (XRF) mapping showed that Ce translocation was confined to the pharyngeal valve and foregut. Ce(NO3)3 exposure significantly decreased growth, fertility, and reproduction, caused slightly reduced fecundity. XRF mapping and histological analysis revealed severe tissue deformities colocalized with retained Ce surrounding the pharyngeal valve. Both forms of Ce activated the sod-1 antioxidant defense, particularly in the pharynx, whereas no significant effects on the cellular redox balance were identified. The CeO2 NP-induced deformities did not appear to impair the pharyngeal function or feeding ability as growth effects were restricted to Ce(NO3)3 exposure. The results demonstrate the utility of integrated submicron-resolution SR-based XRF elemental mapping of tissue-specific distribution and adverse effect analysis to obtain robust toxicological evaluations of metal-containing contaminants.

Chronic effects of cerium dioxide nanoparticles on biological nitrogen removal and nitrous oxide emission: Insight into impact mechanism and performance recovery potential

The influence of cerium dioxide nanoparticles (CeO2 NPs) on biological nitrogen removal and associated nitrous oxide (N2O) emission has seldom been addressed yet. Herein, the chronic effect of CeO2 NPs on the nitrogen transformation processes during wastewater treatment and the impacted system's self-recovery potential after CeO2 NP stress removal were investigated. CeO2 NP of 10–50 mg/L induced significant declines of the ammonia nitrogen (NH4+-N) and the total nitrogen removal efficiencies, but triggered the nitrite accumulation and the N2O emission. The N2O reductase (NOS) activity was negatively correlated with the N2O emission level, and the inhibition of NOS activity under CeO2 NP stress was probably due to the depressions of the sludge denitrifiers' metabolic activities. The NH4+-N removal efficiency was successfully regained after the recovery period although the N2O emission level was still higher than the pre-exposure period, which was probably due to the residual CeO2 NPs inside the activated sludge.

An integrated ICP-MS-based analytical approach to fractionate and characterize ionic and nanoparticulate Ce species.

Cerium dioxide nanoparticles (CeO2 NPs) are widely used in various fields, leading to concern about their effect on human health. When conducting in vivo investigations of CeO2 NPs, the challenge is to fractionate ionic Ce and CeO2 NPs and to characterize CeO2 NPs without changing their properties/state. To meet this challenge, we developed an integrated inductively coupled plasma-mass spectrometry (ICP-MS)-based analytical approach in which ultrafiltration is used to fractionate ionic and nanoparticulate Ce species while CeO2 NPs are characterized by single particle-ICP-MS (sp-ICP-MS). We used this technique to compare the effects of two sample pretreatment methods, alkaline and enzymatic pretreatments, on ionic Ce and CeO2 NPs. Results showed that enzymatic pretreatment was more efficient in extracting ionic Ce or CeO2 NPs from animal tissues. Moreover, results further showed that the properties/states of all ionic and nanoparticulate Ce species were well preserved. The rates of recovery of both species were over 85%; the size distribution of CeO2 NPs was comparable to that of original NPs. We then applied this analytical approach, including the enzymatic pretreatment and ICP-MS-based analytical techniques, to investigate the bioaccumulation and biotransformation of CeO2 NPs in mice. It was found that the thymus acts as a "holding station" in CeO2 NP translocation in vivo. CeO2 NP biotransformation was reported to be organ-specific. This is the first study to evaluate the impact of enzymatic and alkaline pretreatment on Ce species, namely ionic Ce and CeO2 NPs. This integrated ICP-MS-based analytical approach enables us to conduct in vivo biotransformation investigations of CeO2 NPs.

Anti-Inflammatory CeO2 Nanoparticles Prevented Cytotoxicity Due to Exogenous Nitric Oxide Donors via Induction Rather Than Inhibition of Superoxide/Nitric Oxide in HUVE Cells.

The mechanism behind the cytoprotective potential of cerium oxide nanoparticles (CeO2 NPs) against cytotoxic nitric oxide (NO) donors and H2O2 is still not clear. Synthesized and characterized CeO2 NPs significantly ameliorated the lipopolysaccharide (LPS)-induced cytokines IL-1β and TNF-α. The main goal of this study was to determine the capacities of NPs regarding signaling effects that could have occurred due to reactive oxygen species (ROS) and/or NO, since NP-induced ROS/NO did not lead to toxicity in HUVE cells. Concentrations that induced 50% cell death (i.e., IC50s) of two NO donors (DETA-NO; 1250 ± 110 µM and sodium nitroprusside (SNP); 950 ± 89 µM) along with the IC50 of H2O2 (120 ± 7 µM) were utilized to evaluate cytoprotective potential and its underlying mechanism. We determined total ROS (as a collective marker of hydrogen peroxide, superoxide radical (O2•−), hydroxyl radical, etc.) by DCFH-DA and used a O2•− specific probe DHE to decipher prominent ROS. The findings revealed that signaling effects mediated mainly by O2•− and/or NO are responsible for the amelioration of toxicity by CeO2 NPs at 100 µg/mL. The unaltered effect on mitochondrial membrane potential (MMP) due to NP exposure and, again, CeO2 NPs-mediated recovery in the loss of MMP due to exogenous NO donors and H2O2 suggested that NP-mediated O2•− production might be extra-mitochondrial. Data on activated glutathione reductase (GR) and unaffected glutathione peroxidase (GPx) activities partially explain the mechanism behind the NP-induced gain in GSH and persistent cytoplasmic ROS. The promoted antioxidant capacity due to non-cytotoxic ROS and/or NO production, rather than inhibition, by CeO2 NP treatment may allow cells to develop the capacity to tolerate exogenously induced toxicity.

Size-Dependent Cytotoxicity and Reactive Oxygen Species of Cerium Oxide Nanoparticles in Human Retinal Pigment Epithelia Cells.

PurposeThe use of cerium oxide nanoparticles (CeO2 NPs), a lanthanide element oxide and bivalent compound, has been growing continuously in industry and biomedicine. Due to their wide application, the potential human health problems of CeO2 NPs have attracted attention, but studies on the toxicity of this compound to human eyes are lacking. This study investigated the cytotoxicity and reactive oxygen species (ROS) of CeO2 NPs in human retinal pigment epithelial cells (ARPE-19 cells).MethodsUsing the transmission electron microscope (TEM), the size distribution and shape of CeO2 NPs were characterized. To explore the effect of CeO2 NP size on ophthalmic toxicity in vitro, three sizes (15, 30 and 45 nm) of CeO2 NPs were investigated using ATP content measurement, LDH release measurement and cell proliferation assay in ARPE-19 cells. ROS values and mitochondrial membrane potential depolarization were evaluated by H2DCF-DA staining and JC-1 staining. Morphology changes were detected using a phase-contrast microscope.ResultsThe cytotoxicity of 15 nm CeO2 NPs was found to be the highest and hence was further explored. Treatment with 15 nm CeO2 NPs caused the morphology of ARPE-19 cells to change in a dose- and time-dependent manner. Moreover, the treatment induced excessive ROS generation and mitochondrial membrane potential depolarization. In addition, cytotoxicity was attenuated by the application of a ROS scavenger N-acetyl-L- cysteine (NAC).ConclusionCeO2 NPs induced cytotoxicity in ARPE-19 cells and excessive production of ROS and decreasing mitochondrial membrane potential. The Overproduction of ROS partially contributes to CeO2 NP-induced cytotoxicity.

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

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

Impact of multigenerational exposure to AgNO3 or NM300K Ag NPs on antioxidant defense and oxidative stress in Caenorhabditis elegans

Adaptation of the nematode Caenorhabditis elegans towards NM300K silver nanoparticles (Ag NPs) has previously been demonstrated. In the current study, the sensitivity to a range of secondary stressors (CeO2 NP, Ce3+, Cu2+, Cd2+, and Paraquat) following the multigenerational exposure to silver nanoparticles (Ag NPs NM300K) or AgNO3 was investigated. This revealed improved tolerance to the ROS inducer Paraquat with higher fecundity after pre-exposure to Ag NP, indicating an involvement of reactive oxygen species (ROS) metabolism in the adaptive response to NM300K. The potential contribution of the antioxidant defenses related to adaptive responses was investigated across six generations of exposure using the sod-1::GFP reporter (GA508), and the Grx1-roGFP2 (GRX) biosensor strains. Results showed an increase in sod-1 expression by the F3 generation, accompanied by a reduction of GSSG/GSH ratios, from both AgNO3 and Ag NP exposures. Continuous exposure to AgNO3 and Ag NP until the F6 generation resulted in a decreased sod-1 expression, with a concomitant increase in GSSG/GSH ratios. The results thus show that despite an initial enhancement, the continuous exposure to Ag caused a severe impairment of the antioxidant defense capacity in C. elegans.