• Korean Journal of Veterinary Research
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• v.55 no.2
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• pp.133-139
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• 2015

The increasing uses of zinc oxide nanoparticles (nZnO) in industrial and personal care products raise possible danger of using nZnO in human. To determine whether ZnO induces size-dependent anomalies during embryonic organogenesis, mouse embryos on embryonic day 8.5 were cultured for 2 days under 50, 100, and $150{\mu}g$ of nZnO (< 100 nm) or micro-sized ZnO (mZnO; $80{\pm}25{\mu}m$), after which the morphological changes, cumulative quantity of Zn particles, and expressions of antioxidant and apoptotic genes were investigated. Although embryos exposed to $50{\mu}g$ of ZnO exhibited no defects on organogenesis, embryos exposed to over $100{\mu}g$ of ZnO showed increasing anomalies. Embryos treated with $150{\mu}g$ of nZnO revealed significant changes in Zn absorption level and morphological parameters including yolk sac diameter, head length, flexion, hindbrain, forebrain, branchial bars, maxillary process, mandibular process, forelimb, and total score compared to the same dose of mZnO-treated embryos. Furthermore, CuZn-superoxide dismutase, cytoplasmic glutathione peroxidase (GPx) and phospholipid hydroperoxidase GPx mRNA levels were significantly decreased, but caspase-3 mRNA level was greatly increased in nZnO-treated embryos as compared to normal control embryos. These findings indicate that nZnO has severer teratogenic effects than mZnO in developing embryos.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2051-2057
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• 2011

Several studies have demonstrated that nanoparticles (NPs) have toxic effects on cultured cell lines, yet there are no clear data describing the overall molecular changes induced by NPs currently in use for human applications. In this study, the in vitro cytotoxicity of three oxide NPs of around 100 nm size, namely, mesoporous silica (MCM-41), iron oxide ($Fe_2O_3$-NPs), and zinc oxide (ZnO-NPs), was evaluated in the human embryonic kidney cell line HEK293. Cell viability assays demonstrated that 100 ${\mu}g/mL$ MCM-41, 100 ${\mu}g/mL$ $Fe_2O_3$, and 12.5 ${\mu}g/mL$ ZnO exhibited 20% reductions in HEK293 cell viability in 24 hrs. DNA microarray analysis was performed on cells treated with these oxide NPs and further validated by real time PCR to understand cytotoxic changes occurring at the molecular level. Microarray analysis of NP-treated cells identified a number of up- and down-regulated genes that were found to be associated with inflammation, stress, and the cell death and defense response. At both the cellular and molecular levels, the toxicity was observed in the following order: ZnO-NPs > $Fe_2O_3$-NPs > MCM-41. In conclusion, our study provides important information regarding the toxicity of these three commonly used oxide NPs, which should be useful in future biomedical applications of these nanoparticles.

• Journal of Environmental Health Sciences
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• v.41 no.1
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• pp.17-23
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• 2015

Objectives: The cytotoxcities of Au, Ag, SWCNT, $SiO_2$, and ZnO nanomaterials were evaluated in order to assess their potential toxicological effects in in vitro cell models using colony forming efficiency (CFE) assay. Methods: The CFE assay of the test materials was carried out on Hep G2 cells. The size distribution of nanomaterials was studied by transmission electron microscopy (TEM). Changes in cell viability after treatment with a toxicant will result in a decreased number of colonies formed in comparison to solvent. Results: The TEM images show that all the particles except SWCNT and ZnO can be considered approximately spherical. The gold and $SiO_2$ nanoparticles show no response (no toxicity) in concentration response experiments. A statistically significant toxic effect was found in Hep G2 cells treated with Ag, SWCNT and ZnO nanomaterials. Conclusion: In this study, we considered CFE assay to be a promising test for screening studies for cytotoxicity with physicochemical analysis.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.710-715
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• 2018

In this study, $ZnFe_2O_4@SnO_2@TiO_2$ core-shell nanoparticles (NPs), a photocatalytic material with magnetic properties, were synthesized through a three-step process. Structural properties were investigated using X-ray diffraction (XRD) analysis. It was confirmed that $ZnFe_2O_4$ of the spinel, $SnO_2$ of the tetragonal and $TiO_2$ of the anatase structure were synthesized. The magnetic properties of synthesized materials were studied by a vibrating sample magnetometer (VSM). The saturation magnetization value of $ZnFe_2O_4$, a core material, was confirmed at 33.084 emu/g. As a result of the formation of $SnO_2$ and $TiO_2$ layers, the magnetism due to the increase in thickness was reduced by 33% and 40%, respectively, but sufficient magnetic properties were reserved. The photocatalytic efficiency of synthesized materials was measured using methylene blue (MB). The efficiency of the core material was about 4.2%, and as a result of the formation of $SnO_2$ and $TiO_2$ shell, it increased to 73% and 96%, respectively while maintaining a high photocatalytic efficiency. In addition, the antibacterial activity was validated via the inhibition zone by using E. Coli and S. Aureus. The formation of shells resulted in a wider inhibition zone, which is in good agreement with photocatalytic efficiency measurements.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.220-225
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• 2020

Gallium oxide nano-powder, the key starting material for IGZO target, is fabricated by gas phase synthesis using a new apparatus consist of reaction, transportation, and collection parts. As a result of gallium metal evaporation above 1150℃, Ga2O3 nano-powders, are successfully synthesized. The SEM images of the synthesized powders displace the spherical shaped powders without severe agglomeration. X-ray diffraction and PSA analysis show that the higher temperature at the reaction part results in the better crystallinity and larger powder size of the synthesized Ga2O3. To see the applicability to IGZO target, Ga2O3 nano-powders synthesized at 1250℃ are mixed with indium oxide and zinc oxide (In2O3 : Ga2O3 : ZnO = 1 : 1 : 1), and then sintered at 1400~1500℃. The highest sintered density of 5.83 g/㎤ (= 91 % of relative density) is achieved when sintered at 1450℃, showing better sinterability compared to the commercially available Ga2O3 powder, which has 5.61 g/㎤ of sintered density at the same condition.

• Advances in environmental research
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• v.7 no.3
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• pp.213-223
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• 2018

Continuous input into the aquatic ecosystem and persistent structures have created concern of antibiotics, primarily due to the potential for the development of antimicrobial resistance. Degradation kinetics and mineralization of vancomycin B (VAN-B) by photocatalysis using $TiO_2$ and ZnO nanoparticles was monitored at natural pH conditions. Photocatalysis (PC) efficiency was followed by means of UV absorbance, total organic carbon (TOC), and HPLC results to better monitor degradation of VAN-B itself. Experiments were run for two initial VAN-B concentrations ($20-50mgL^{-1}$) and using two catalysts $TiO_2$ and ZnO at different concentrations (0.1 and $0.5gL^{-1}$) in a multi-lamp batch reactor system (200 mL water volume). Furthermore, a set of toxicity tests with Daphnia magna was performed to evaluate the potential toxicity of oxidation by-products of VAN-B. Formation of intermediates such as chlorides and nitrates were monitored. A rapid VAN-B degradation was observed in ZnO-PC system (85% to 70% at 10 min), while total mineralization was observed to be relatively slower than $TiO_2-PC$ system (59% to 73% at 90 min). Treatment efficiency and mechanism of degradation directly affected the rate of transformation and by-products formation that gave rise to toxicity in the treated samples.

• Journal of the Korean Ceramic Society
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• v.56 no.5
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• pp.474-482
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• 2019

Chromium-doped zinc ferrite nanoparticles with the general formula Cr_yZnFe_2-yO₄ (y = 0, 0.025, 0.05, 0.075, and 0.1) were synthesized by a surfactant-assisted chemical co-precipitation route using metal nitrate salt precursors. The phase purity and structural parameters were determined by powder X-ray diffraction. The concentration of Cr³⁺ doped into ZnFe₂O₄ (ZF) noticeably affected the crystallite size, which was in the range of 22 nm to 36 nm, and all samples showed a single cubic spinel structure without any secondary phase or impurities. The lattice parameter, X-ray density, and skeletal density increased with an increase in the Cr-doping concentration; on the other hand, a decreasing trend was observed for the particle size and porosity. The influence of Cr³⁺ substitution on ZF magnetic properties were studied under an applied field of 15 kOe. The overall results revealed that the incorporation of a small amount of Cr dopant changed the structural, electrical, and magnetic properties of ZF.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.120-120
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• 2003

The metallic oxide nanomaterials including ZnO, Ga$_2$O$_3$, TiO$_2$, and SnO$_2$ have been synthesized by a number of methods including laser ablation, arc discharge, thermal annealing procedure, catalytic growth processes, and vapor transport. We have been interested in preparing the nanomaterials of Ga$_2$O$_3$, which is a wide band gap semiconductor (E$_{g}$ =4.9 eV) and used as insulating oxide layer for all gallium-based semiconductor. Ga$_2$O$_3$ is stable at high temperature and a transparent oxide, which has potential application in optoelectronic devices. The Ga$_2$O$_3$ nanoparticles and nanobelts were produced using GaN single crystals, which were grown by flux method inside SUS$^{TM}$ cell using a Na flux and exhibit plate-like morphologies with 4 ~ 5 mm in size. In these experiments, the conventional electric furnace was used. GaN single crystals were pulverized in form of powder for the growth of Ga$_2$O$_3$ nanomaterials. The structure, morphology and composition of the products were studied mainly by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM).).

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.357-363
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• 2015

The development of the environment-friendly tire that meets the standard requirements according to tire labeling system can be improved through using highly homogeneous silica immobilized zinc oxide nanoparticles. In this study, a considerable amount of nanoporous silica was essentially added into nano zinc oxide to improve the physiochemical properties of the formed composite. The introduction of nanoporous silica materials in the composite facilitates the improvement of the wear-resistance and increases the elasticity of the tread. Therefore, the introduction of nanoporous silica can replace carbon black as filler in the formation of composites with desirable properties for conventional green tire. Herein, mesoporous silica immobilized zinc oxide nanoparticle with desirable properties for rubber compounds was investigated. Composites with homogeneous dispersion were obtained in the absence of dispersants. The dispersion stability was controlled through varying the molar ratio, ageing time and mixing order of the reactants. A superior dispersion was achieved in the sample obtained using 0.03 mol of zinc precursor as it had the smallest grain size (50.5 nm) and then immobilized in silica aged for 10 days. Moreover, the specific surface area of this sample was the highest ($649m^2/g$).

• Advances in Energy Research
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• v.2 no.1
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• pp.33-45
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• 2014

Photocatalytic hydrogen generation by water splitting ($H_2O_{(1)}{\rightarrow}H_2_{(g)}+1/2O_2_{(g)}$) has been studied on photocatalysts based on Zn, Cd, Fe and Cu, synthesized by coprecipitation. Iron and copper nanoparticles were incorporated as cocatalysts to enhance the photocatalytic activity of the ZnCd solid solution. The effect of the different synthesis parameters (temperature, elemental atomic ratios, amount of Cu and Fe incorporated in the catalyst and calcination temperature) on the photocatalytic production of hydrogen has been studied in order to determine the best experimental synthesis conditions. The catalysts have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and BET. The experiments of photocatalytic water splitting were performed in aqueous solution of the photocatalysts previously dispersed in a soft ultrasound bath. The photocatalysts were irradiated under different lights ranging from 220 to 700 nm. The photocatalytic activity was found to be clearly dependent on the specific area of the photocatalyst.