An Assessment of the Impact of SiO2 Nanoparticles of Different Sizes on the Rest/Wake Behavior and the Developmental Profile of Zebrafish Larvae

In this study, zebrafish larvae are introduced as an in vivo platform to examine the neurotoxicity and developmental toxicity associated with continuous exposure to a concentration gradient of different sizes of SiO₂ nanoparticles (15 nm and 50 nm diameter) to determine the dose effect and size effect of SiO₂ nanoparticle (NP)‐induced toxicity. Bovine serum albumin (BSA‐V) is utilized as a stabilizing agent to prevent coagulation of the SiO₂ nanoparticles. To the best of our knowledge, this study is the first to describe locomotor activity assays linking rest/wake behavioral profiles for the purpose of investigating the neurotoxicity of NPs. In addition, developmental toxicological endpoints including mortality, LC₅₀, malformation, and cartilaginous deformity are assessed. The results show a concentration‐dependent increase in behavioral neurotoxicity, mortality, and malformation among larvae treated with the SiO₂ nanoparticles of 15 nm and 50 nm. A comparison of the 15 nm and 50 nm NPs by K‐means clustering analysis demonstrates that the 15 nm NPs have a greater neurotoxic effect than the 50 nm NPs, with the 50 nm NPs exhibiting greater developmental toxicity on the zebrafish larvae than the 15 nm NPs.     

Mechanistic Investigation of the Biological Effects of SiO2, TiO2, and ZnO Nanoparticles on Intestinal Cells

Silicon dioxide (SiO₂), titanium dioxide (TiO₂), and zinc oxide (ZnO) are currently among the most widely used nanoparticles (NPs) in the food industry. This could potentially lead to unintended exposure of the gastrointestinal tract to these NPs. This study aims to investigate the potential side‐effects of these food‐borne NPs on intestinal cells and to mechanistically understand the observed biological responses. Among the panel of tested NPs, ZnO NPs are the most toxic. Consistently in all three tested intestinal cell models, ZnO NPs invoke the most inflammatory responses from the cells and induce the highest intracellular production of reactive oxygen species (ROS). The elevated ROS levels induce significant damage to the DNA of the cells, resulting in cell‐cycle arrest and subsequently cell death. In contrast, both SiO₂ and TiO₂ NPs elicit minimum biological responses from the intestinal cells. Overall, the study showcases the varying capability of the food‐borne NPs to induce a cellular response in the intestinal cells. In addition to physicochemical differences in the NPs, the genetic landscape of the intestinal cell models governs the toxicology profile of these food‐borne NPs.     

Formation of a Monolayer Protein Corona around Polystyrene Nanoparticles and Implications for Nanoparticle Agglomeration

Nanoparticle (NP) interactions with cells and organisms are mediated by a biomolecular adsorption layer, the so‐called “protein corona.” An in‐depth understanding of the corona is a prerequisite to successful and safe application of NPs in biology and medicine. In this work, earlier in situ investigations on small NPs are extended to large polystyrene (PS) NPs of up to 100 nm diameter, using human transferrin (Tf) and human serum albumin (HSA) as model proteins. Direct NP sizing experiments reveal a reversibly bound monolayer protein shell (under saturating conditions) on hydrophilic, carboxyl‐functionalized (PS‐COOH) NPs, as was earlier observed for much smaller NPs. In contrast, protein binding on hydrophobic, sulfated (PS‐OSO₃H) NPs in solvent of low ionic strength is completely irreversible; nevertheless, the thickness of the observed protein corona again corresponds to a protein monolayer. Under conditions of reduced charge repulsion (higher ionic strength), the NPs are colloidally unstable and form large clusters below a certain protein–NP stoichiometric ratio, indicating that the adsorbed proteins induce NP agglomeration. This comprehensive characterization of the persistent protein corona on PS‐OSO₃H NPs by nanoparticle sizing and quantitative fluorescence microscopy/nanoscopy reveals mechanistic aspects of molecular interactions occurring during exposure of NPs to biofluids.     

Quantitative Proteomics Study Reveals Changes in the Molecular Landscape of Human Embryonic Stem Cells with Impaired Stem Cell Differentiation upon Exposure to Titanium Dioxide Nanoparticles

The increasing number of nanoparticles (NPs) being used in various industries has led to growing concerns of potential hazards that NP exposure can incur on human health. However, its global effects on humans and the underlying mechanisms are not systemically studied. Human embryonic stem cells (hESCs), with the ability to differentiate to any cell types, provide a unique system to assess cellular, developmental, and functional toxicity in vitro within a single system highly relevant to human physiology. Here, the quantitative proteomics approach is adopted to evaluate the molecular consequences of titanium dioxide NPs (TiO₂ NPs) exposure in hESCs. The study identifies ≈328 unique proteins significantly affected by TiO₂ NPs exposure. Proteomics analysis highlights that TiO₂ NPs can induce DNA damage, elevated oxidative stress, apoptotic responses, and cellular differentiation. Furthermore, in vivo analysis demonstrates remarkable reduction in the ability of hESCs in teratoma formation after TiO₂ NPs exposure, suggesting impaired pluripotency. Subsequently, it is found that TiO₂ NPs can disrupt hESC mesoderm differentiation into cardiomyocytes. The study unveils comprehensive changes in the molecular landscape of hESCs by TiO₂ NPs and identifies the impact which TiO₂ NPs can have on the pluripotency and differentiation properties of human stem cells.     

Toxicological Aspects of Long‐Term Treatment of Keratinocytes with ZnO and TiO2 Nanoparticles

Sunscreens containing ZnO and TiO₂ nanoparticles (NPs) are increasingly applied to skin over long time periods to reduce the risk of skin cancer. However, long‐term toxicological studies of NPs are very sparse. The in vitro toxicity of ZnO and TiO₂ NPs on keratinocytes over short‐ and long‐term applications is reported. The effects studied are intracellular formation of radicals, alterations in cell morphology, mitochondrial activity, and cell‐cycle distribution. Cellular response depends on the type of NP, concentration, and exposure time. ZnO NPs have more pronounced adverse effects on keratinocytes than TiO₂. TiO₂ has no effect on cell viability up to 100 μg mL^?1, whereas ZnO reduces viability above 15 μg mL^?1 after short‐term exposure. Prolonged exposure to ZnO NPs at 10 μg mL^?1 results in decreased mitochondrial activity, loss of normal cell morphology, and disturbances in cell‐cycle distribution. From this point of view TiO₂ has no harmful effect. More nanotubular intercellular structures are observed in keratinocytes exposed to either type of NP than in untreated cells. This observation may indicate cellular transformation from normal to tumor cells due to NP treatment. Transmission electron microscopy images show NPs in vesicles within the cell cytoplasm, particularly in early and late endosomes and amphisomes. Contrary to insoluble TiO₂, partially soluble ZnO stimulates generation of reactive oxygen species to swamp the cell redox defense system thus initiating the death processes, seen also in cell‐cycle distribution and fluorescence imaging. Long‐term exposure to NPs has adverse effects on human keratinocytes in vitro, which indicates a potential health risk.     

Effects of metal oxide nanoparticles on combustion and gas-generating performance of NaN3/Al composite powders ignited using a microhotplate platform

We investigated the effects of different metal oxide (MO) nanoparticles (e.g., CuO, KIO₄, Fe₂O₃) on the combustion and gas-generating characteristics of sodium azide microparticle (NaN₃ MP; gas-generating agent) and aluminum nanoparticle (Al NP; heat source) composite powders. The NaN₃ MP/Al NP/MO NP composite powders were stably ignited using a microhotplate (MHP) heater. The addition of CuO and KIO₄ to the NaN₃ MP/Al NP composite powders resulted in relatively high burn rates and high pressurization rates upon MHP-assisted ignition. This suggests that the highly reactive CuO and KIO₄ NPs significantly increased the combustion of the Al NPs; as a result, sufficient heat energy was generated via the active aluminothermic reaction to thermally decompose the NaN₃ MPs. Finally, the gas generating properties of NaN₃ MP/Al NP composite powders mixed with various MO NPs were tested using homemade inflatable small airbags. The airbags were fully inflated within ~20 ms when CuO and KIO₄ NPs were added to the NaN₃ MP/Al NP composite powders. However, the addition of Fe₂O₃ NPs to the NaN₃ MP/Al NP composite powder resulted in a slow and only partial inflation of the airbag due to an incomplete aluminothermic reaction, which was due to a slow combustion reaction between the Al NPs and relatively weak oxidizer of the Fe₂O₃ NPs. This suggests that the rapid, stable, and complete thermal decomposition of NaN₃ MP/Al NP composites can be effectively achieved by employing highly reactive nanoscale oxidizers.     

Toxicity of copper oxide nanoparticles: a review study

Copper oxide nanoparticles (CuO NPs) use has exponentially increased in various applications (such as industrial catalyst, gas sensors, electronic materials, biomedicines, environmental remediation) due to their flexible properties, i.e. large surface area to volume ratio. These broad applications, however, have increased human exposure and thus the potential risk related to their short‐ and long‐term toxicity. Their release in environment has drawn considerable attention which has become an eminent area of research and development. To understand the toxicological impact of CuO NPs, this review summarises the in‐vitro and in‐vivo toxicity of CuO NPs subjected to species (bacterial, algae, fish, rats, human cell lines) used for toxicological hazard assessment. The key factors that influence the toxicity of CuO NPs such as particle shape, size, surface functionalisation, time–dose interaction and animal and cell models are elaborated. The literature evidences that the CuO NPs exposure to the living systems results in reactive oxygen species generation, oxidative stress, inflammation, cytotoxicity, genotoxicity and immunotoxicity. However, the physio‐chemical characteristics of CuO NPs, concentration, mode of exposure, animal model and assessment characteristics are the main perspectives that define toxicology of CuO NPs.Inspec keywords: catalysts, nanofabrication, reviews, oxidation, toxicology, gas sensors, cellular biophysics, copper compounds, nanoparticles, biochemistryOther keywords: copper oxide nanoparticles, environmental remediation, short‐ term toxicity, long‐term toxicity, human cell lines, CuO NPs exposure, physiochemical characteristics, mode of exposure, animal model, ssessment characteristics, toxicology, time‐dose interaction, oxidative stress, inflammation, cytotoxicity, genotoxicity, immunotoxicity, toxicological hazard assessment, algae species, bacterial species, fish, rats, CuO     

Label‐free and dynamic monitoring of cytotoxicity to the blood–brain barrier cells treated with nanometre copper oxide

A cytotoxicity study was conducted with a primary culture of the nervous system cells, including brain microvascular endothelial cells (BMECs) and astrocytes, which are important components of the blood–brain barrier. The real‐time cell analysis (RTCA) was used to determine the cytotoxicity of copper‐oxide nanoparticles (CuO NPs). The IC₅₀ values of CuO NPs in astrocytes and BMECs were determined by the RTCA at different exposure times and were used as base values for further research. DNA damage after exposure to CuO NPs for 3 and 24 h was assessed using comet assay at the IC₅₀ obtained from RTCA. The onset time of cytotoxicity induced by CuO NPs was 2 and 2–4 h post‐exposure in BMECs and astrocytes, respectively. Furthermore, the degree of cytotoxicity induced by exposure to CuO NPs for 24–48 h in the BMECs and astrocytes was similar. Treatment with CuO NPs at 1/2*IC₅₀ and 1/5*IC₅₀ for 3 h induced genotoxicity in both cells as assessed by a measurement of DNA damage, although no cytotoxicity was observed. However, significant DNA damage was observed at all concentrations of CuO NPs used in this study, when the treatment time was 24 h.Inspec keywords: biochemistry, blood, brain, cellular biophysics, copper compounds, DNA, molecular biophysics, nanoparticles, toxicologyOther keywords: label‐free cytotoxicity monitoring, dynamic cytotoxicity monitoring, blood‐brain barrier cells, nervous system cells, brain microvascular endothelial cells, astrocytes, real‐time cell analysis, copper‐oxide nanoparticles, comet assay, genotoxicity, DNA damage measurement, time 24 h to 48 h, time 2 h to 4 h, CuO     

Multigenerational Exposures of Daphnia Magna to Pristine and Aged Silver Nanoparticles: Epigenetic Changes and Phenotypical Ageing Related Effects

Engineered nanoparticles (NPs) undergo physical, chemical, and biological transformation after environmental release, resulting in different properties of the “aged” versus “pristine” forms. While many studies have investigated the ecotoxicological effects of silver (Ag) NPs, the majority focus on “pristine” Ag NPs in simple exposure media, rather than investigating realistic environmental exposure scenarios with transformed NPs. Here, the effects of “pristine” and “aged” Ag NPs are systematically evaluated with different surface coatings on Daphnia magna over four generations, comparing continuous exposure versus parental only exposure to assess recovery potential for three generations. Biological endpoints including survival, growth and reproduction and genetic effects associated with Ag NP exposure are investigated. Parental exposure to “pristine” Ag NPs has an inhibitory effect on reproduction, inducing expression of antioxidant stress related genes and reducing survival. Pristine Ag NPs also induce morphological changes including tail losses and lipid accumulation associated with aging phenotypes in the heart, abdomen, and abdominal claw. These effects are epigenetic remaining two generations post‐maternal exposure (F2 and F3). Exposure to identical Ag NPs (same concentrations) aged for 6 months in environmentally realistic water containing natural organic matter shows considerably reduced toxicological effects in continuously exposed generations and to the recovery generations.     

铈掺杂氧化铜纳米颗粒的制备及其抗菌性能研究

采用水热法制备了铈离子掺杂的氧化铜纳米颗粒(Ce-CuO NPs)。FESEM图像显示掺杂氧化铜为球形和近球形颗粒;XRD图谱表明,当掺杂量低于10%时,图谱中只出现了单斜结构的CuO衍射峰,当掺杂量增加至15%时,形成了CeO2独立相;ICP分析表明,铈元素的掺杂对CuO NPs中铜离子的释放具有促进作用。铈掺杂氧化铜纳米颗粒的抗菌测试结果显示,其对革兰氏阳性菌金黄色葡萄球菌(S.aureus)的抗菌能力,较革兰氏阴性菌大肠杆菌(E.coli)更为显著;其中,5% Ce-CuO NPs在0.05 mg/mL的低浓度下表现出最佳的抗菌效果。Cu^2+与细菌细胞表面的结合在抑制细菌生长的过程中起到重要作用。     

Evaluating the effect of green synthesised copper oxide nanoparticles on oxidative stress and mitochondrial function using murine model

Green synthesis of metal nanoparticles (NPs) has now received the attention of researchers due to ease of preparation and its potential to overcome hazards of these chemicals for an eco‐friendly milieu. In this study, copper oxide (CuO) NPs were synthesised via Desmodium gangeticum aqueous root extract and standard chemical method, further characterised by UV–visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, Thermogravimetric analysis and scanning electron microscopy. The nephrotoxicity of the NP obtained from two routes were compared and evaluated at subcellular level in Wistar rat, renal proximal epithelial cells (LLC PK1 cell lines) and isolated renal mitochondria. CuO NP synthesised by chemical route showed prominent nephrotoxicity measured via adverse cytotoxicity to LLC PK1 cells, elevated renal oxidative stress and damage to renal tissue (determined by impaired alanine transaminase, aspartate transaminase, urea, uric acid and creatinine in the blood). However, at the level of cell organelle, CuO NP from both routes are non‐toxic to mitochondrial functional activity. The authors’ finding suggests that CuO NP synthesised by chemical route may induce nephrotoxicity, but may be overcome by co‐administration of antioxidants, as it is not mito‐toxic.Inspec keywords: cellular biophysics, scanning electron microscopy, toxicology, nanomedicine, oxidation, nanoparticles, enzymes, blood, visible spectra, X‐ray diffraction, biochemistry, nanofabrication, antibacterial activity, ultraviolet spectra, copper compounds, Fourier transform infrared spectra, molecular biophysics, thermal analysis, biological tissuesOther keywords: green synthesised copper oxide nanoparticles, murine model, metal nanoparticles, chemicals, eco‐friendly milieu, copper oxide NPs, standard chemical method, X‐ray diffraction, scanning electron microscopy, subcellular level, renal proximal epithelial cells, LLC PK1 cell lines, renal mitochondria, renal tissue, cell organelle, mitochondrial functional activity, UV‐visible spectroscopy, Fourier transform infrared spectroscopy, nephrotoxicity, renal oxidative stress, Desmodium gangeticum aqueous root extract, thermogravimetric analysis, Wistar rat, cytotoxicity, impaired alanine transaminase, aspartate transaminase, urea, uric acid, creatinine, blood, CuO     

Tolerogenic Iron Oxide Nanoparticles in Type 1 Diabetes: Biodistribution and Pharmacokinetics Studies in Nonobese Diabetic Mice

Nanoparticle (NP) administration is among the most attractive approaches to exploit the synergy of different copackaged molecules for the same target. In this work, iron oxide NPs are surface‐engineered for the copackaging of the autoantigen proinsulin, a major target of adaptive immunity in type 1 diabetes (T1D), and 2‐(1′H‐indole‐3′‐carbonyl)‐thiazole‐4‐carboxylic acid methylester (ITE), a small drug conditioning a tolerogenic environment. Magnetic resonance imaging (MRI) combined with magnetic quantification are used to investigate NP biokinetics in nonobese diabetic (NOD) mice and control mice in different organs. Different NP biodistribution, with in particular enhanced kidney elimination and a stronger accumulation in the pancreas for prediabetic NOD mice, is observed. This is related to preferential NP accumulation in the pancreatic inflammatory zone and to enhancement of renal elimination by diabetic nephropathy. For both mouse strains, an MRI T2 contrast enhancement at 72 h in the liver, pancreas, and kidneys, and indicating recirculating NPs, is also found. This unexpected result is confirmed by magnetic quantification at different time points as well as by histological evaluation. Besides, such NPs are potential MRI contrast agents for early diagnosis of T1D.     

Zebrafish Embryos Allow Prediction of Nanoparticle Circulation Times in Mice and Facilitate Quantification of Nanoparticle–Cell Interactions

The zebrafish embryo is a vertebrate well suited for visualizing nanoparticles at high resolution in live animals. Its optical transparency and genetic versatility allow noninvasive, real‐time observations of vascular flow of nanoparticles and their interactions with cells throughout the body. As a consequence, this system enables the acquisition of quantitative data that are difficult to obtain in rodents. Until now, a few studies using the zebrafish model have only described semiquantitative results on key nanoparticle parameters. Here, a MACRO dedicated to automated quantitative methods is described for analyzing important parameters of nanoparticle behavior, such as circulation time and interactions with key target cells, macrophages, and endothelial cells. Direct comparison of four nanoparticle (NP) formulations in zebrafish embryos and mice reveals that data obtained in zebrafish can be used to predict NPs' behavior in the mouse model. NPs having long or short blood circulation in rodents behave similarly in the zebrafish embryo, with low circulation times being a consequence of NP uptake into macrophages or endothelial cells. It is proposed that the zebrafish embryo has the potential to become an important intermediate screening system for nanoparticle research to bridge the gap between cell culture studies and preclinical rodent models such as the mouse.     

Aerosol route synthesis of Ni-CeO2-Al2O3 hybrid nanoparticle cluster for catalysis of reductive amination of polypropylene glycol

We demonstrated an aerosol-based approach to synthesize Ni-CeO₂-Al₂O₃ hybrid nanostructure as a potent nanopowder catalyst for the production of polyetheramine via reductive amination of polypropylene glycol. The method combines a gas-phase evaporation-induced self-assembly with two-stage thermal treatments of the aerosol particles. The hybrid Ni-CeO₂ nanoparticles (NPs) composed of ultrafine, homogeneously-distributed nanocrystallites of metallic Ni and ceria were shown to uniformly decorate on the surface of Al₂O₃ nanoparticle cluster (NPC). The composition, physical size and surface state of the hybrid nanostructure were tunable by design. It was found that hybridization with Al₂O₃ or CeO₂ enhanced catalytic activity of the Ni catalyst. A high yield of ≈77% of the desired PEA and a high selectivity to primary amine (≈100%) achieved simultaneously. The surface nitridation of Ni catalyst was effectively suppressed via the incorporation with CeO₂ NPs. An enhanced operation stability was observed by using the Ni-CeO₂-Al₂O₃ hybrid nanostructure as catalyst in comparison to the Ni-only NP. The work demonstrated a facile route for controlled gas-phase synthesis of hybrid nanopowder catalysts using Al₂O₃ NPC as the support matrix and CeO₂ NP as the promoter to further enhance the performance of Ni catalyst toward reductive amination.     

Nanoparticle–Plant Interactions: Two‐Way Traffic

In this Review, an effort is made to discuss the most recent progress and future trend in the two‐way traffic of the interactions between plants and nanoparticles (NPs). One way is the use of plants to synthesize NPs in an environmentally benign manner with a focus on the mechanism and optimization of the synthesis. Another way is the effects of synthetic NPs on plant fate with a focus on the transport mechanisms of NPs within plants as well as NP‐mediated seed germination and plant development. When NPs are in soil, they can be adsorbed at the root surface, followed by their uptake and inter/intracellular movement in the plant tissues. NPs may also be taken up by foliage under aerial deposition, largely through stomata, trichomes, and cuticles, but the exact mode of NP entry into plants is not well documented. The NP–plant interactions may lead to inhibitory or stimulatory effects on seed germination and plant development, depending on NP compositions, concentrations, and plant species. In numerous cases, radiation‐absorbing efficiency, CO₂ assimilation capacity, and delay of chloroplast aging have been reported in the plant response to NP treatments, although the mechanisms involved in these processes remain to be studied.     

Eradication of Multi‐Drug Resistant Bacteria by a Novel Zn‐doped CuO Nanocomposite

Zinc‐doped copper oxide nanoparticles are synthesized and simultaneously deposited on cotton fabric using ultrasound irradiation. The optimization of the processing conditions, the specific reagent ratio, and the precursor concentration results in the formation of uniform nanoparticles with an average size of ≈30 nm. The antibacterial activity of the Zn‐doped CuO Cu_0.88Zn_0.12O in a colloidal suspension or deposited on the fabric is tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) bacteria. A substantial enhancement of 10 000 times in the antimicrobial activity of the Zn–CuO nanocomposite compared to the pure CuO and ZnO nanoparticles (NPs) is observed after 10 min exposure to the bacteria. Similar activities are observed against multidrug‐resistant bacteria (MDR), (i.e., Methicillin‐resistant S. aureus and MDR E. coli) further emphasizing the efficacy of this composite. Finally, the mechanism for this enhanced antibacterial activity is presented.     

Abundant Ce3+ Ions in Au‐CeOx Nanosheets to Enhance CO2 Electroreduction Performance

The electroreduction of CO₂ to CO provides a potential way to solve the environmental problems caused by excess fossil fuel utilization. Loading transition metals on metal oxides is an efficient strategy for CO₂ electroreduction as well as for reducing metal usage. However, it needs a great potential to overcome the energy barrier to increase CO selectivity. This paper describes how 8.7 wt% gold nanoparticles (NPs) loaded on CeO_x nanosheets (NSs) with high Ce³⁺ concentration effectively decrease the overpotential for CO₂ electroreduction. The 3.6 nm gold NPs on CeO_x NSs containing 47.3% Ce³⁺ achieve CO faradaic efficiency of 90.1% at ?0.5 V in 0.1 m KHCO₃ solution. Furthermore, the CO₂ electroreduction activity shows a strong relationship with the fractions of Ce³⁺ on Au‐CeO_x NSs, which has never been reported. In situ surface‐enhanced infrared absorption spectroscopy shows that Au‐CeO_x NSs with high Ce³⁺ concentration promote CO₂ activation and *COOH formation. Theoretical calculations also indicate that the improved performance is attributed to the enhanced *COOH formation on Au‐CeO_x NSs with high Ce³⁺ fraction.     

CuO/CeO2 catalysts prepared with different cerium supports for CO oxidation at low temperature

The activity of a catalyst depends on the nature of its support, its active site, and its preparation method. This study aimed to employ various types of CeO₂ supports such as commercial CeO₂ and self-prepared CeO₂ for the preparation of copper catalysts. The CuO/CeO₂ catalysts were prepared using the polyol process and impregnation method. The catalysts were characterized using Brunauer–Emmett–Teller analysis, scanning electron microscopy, and X-ray analysis, and their catalytic activity for CO removal was evaluated in a microcatalytic reactor. The experimental results showed that the catalytic activity of the CuO/CeO₂ catalysts with different calcination temperatures decreased in the following order: 500 °C > 300 °C > 700 °C. Compared to the impregnation method, the polyol process generated well-dispersed metal particles over the support and showed higher CO removal efficiency with low activation energy. Compared to CuO/CeO₂ catalysts with commercial CeO₂, those with CeO₂ that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO₂ and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO₂-P (pyrolysis) > CuO/CeO₂-C (commercial) > CuO/CeO₂-D (deposition precipitation). CuO/CeO₂-P catalysts showed good activity even at low temperature. The CuO/CeO₂-P(300)-P-120 min catalyst was found to possess the good CO removal rate when the oxygen content was 6%, CO concentration was 500 ppm, catalyst weighed 1.0 g, pollutant gas velocity was 500 mL min⁻¹, SV was 3.7 × 10⁴ h⁻¹, and reaction temperature was 150 °C.     

Biosynthesis and Characterization of Copper Nanoparticles Using Shewanella oneidensis: Application for Click Chemistry

Copper nanoparticles (Cu‐NPs) have a wide range of applications as heterogeneous catalysts. In this study, a novel green biosynthesis route for producing Cu‐NPs using the metal‐reducing bacterium, Shewanella oneidensis is demonstrated. Thin section transmission electron microscopy shows that the Cu‐NPs are predominantly intracellular and present in a typical size range of 20–40 nm. Serial block‐face scanning electron microscopy demonstrates the Cu‐NPs are well‐dispersed across the 3D structure of the cells. X‐ray absorption near‐edge spectroscopy and extended X‐ray absorption fine‐structure spectroscopy analysis show the nanoparticles are Cu(0), however, atomic resolution images and electron energy loss spectroscopy suggest partial oxidation of the surface layer to Cu₂O upon exposure to air. The catalytic activity of the Cu‐NPs is demonstrated in an archetypal “click chemistry” reaction, generating good yields during azide‐alkyne cycloadditions, most likely catalyzed by the Cu(I) surface layer of the nanoparticles. Furthermore, cytochrome deletion mutants suggest a novel metal reduction system is involved in enzymatic Cu(II) reduction and Cu‐NP synthesis, which is not dependent on the Mtr pathway commonly used to reduce other high oxidation state metals in this bacterium. This work demonstrates a novel, simple, green biosynthesis method for producing efficient copper nanoparticle catalysts.     

Preparation,characterization and catalytic properties of CuO/CeO2 system

CeO₂ nano-particles and CuO/CeO₂ system were prepared by sol-gel and impregnation methods and characterized using combined spectroscopic techniques of XRD, XPS, TPR, FT–Raman, BET and HRTEM. It was found the CeO₂ was cubic phase with fluorite structure and CuO was highly dispersed on the CeO₂ particles. Temperature-programmed reduction (TPR) showed a two-step reduction for CuO/CeO₂ catalysts. XPS analysis indicated the presence of redox couple Ce⁴⁺/Ce³⁺ and reduced copper species in the CuO/CeO₂ catalysts. The factors, such as calcination temperature, calcination time and CuO loading, influenced on the catalytic properties of CuO/CeO₂ catalysts.