• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.85-93
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• 2016

We already reported that genetically engineered resveratrol-enriched rice (RR) showed to down-regulate skin melanogenesis. To be developed to increase the bioactivity of RR using calli from plants, RR was adopted for mass production using plant tissue culture technologies. In addition, high-pressure homogenization (HPH) was used to increase the biocompatibility and penetration of the calli from RR into the skin. We aimed to develop anti-melanogenic agents incorporating calli of RR (cRR) and nanoparticles by high-pressure homogenization, examining the synergistic effects on the inhibition of UVB-induced hyperpigmentation. Depigmentation was observed following topical application of micro-cRR, nano-calli of normal rice (cNR), and nano-cRR to ultraviolet B (UVB)-stimulated hyperpigmented guinea pig dorsal skin. Colorimetric analysis, tyrosinase immunostaining, and Fontana-Masson staining for UVB-promoted melanin were performed. Nano-cRR inhibited changes in the melanin color index caused by UVB-promoted hyperpigmentation, and demonstrated stronger anti-melanogenic potential than micro-cRR. In epidermal skin, nano-cRR repressed UVB-promoted melanin granules, thereby suppressing hyperpigmentation. The UVB-enhanced, highly expressed tyrosinase in the basal layer of the epidermis was inhibited by nano-cRR more prominently than by micro-cRR and nano-cNR. The anti-melanogenic potency of nano-cRR also depended on pH and particle size. Nano-cRR shows promising potential to regulate skin pigmentation following UVB exposure.

• Wind and Structures
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• v.24 no.5
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• pp.431-446
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• 2017

As concrete is most usable material in construction industry it's been required to improve its quality. Nowadays, nanotechnology offers the possibility of great advances in construction. In this study, buckling of horizontal concrete columns reinforced with Zinc Oxide (ZnO) nanoparticles is analyzed. Due to the presence of ZnO nanoparticles which have piezoelectric properties, the structure is subjected to electric field for intelligent control. The Column is located in foundation with vertical springs and shear modulus constants. Sinusoidal shear deformation beam theory (SSDBT) is applied to model the structure mathematically. Micro-electro-mechanic model is utilized for obtaining the equivalent properties of system. Using the nonlinear stress-strain relation, energy method and Hamilton's principal, the motion equations are derived. The buckling load of the column is calculated by Difference quadrature method (DQM). The aim of this study is presenting a mathematical model to obtain the buckling load of structure as well as investigating the effect of nanotechnology and electric filed on the buckling behavior of structure. The results indicate that the negative external voltage applied to the structure, increases the stiffness and the buckling load of column. In addition, reinforcing the structure by ZnO nanoparticles, the buckling load of column is increased.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1841-1851
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• 2019

Garcinol, a well-known medicinal phytochemical, was extracted and isolated from the dried fruit rinds of Garcinia quaesita Pierre. In this study, garcinol has successfully used to reduce silver ions to silver in order to synthesize garcinol-capped silver nanoparticles (G-AgNPs). The formation and the structure of G-AgNPs were confirmed by UV-visible spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of garcinol and G-AgNPs were investigated by well diffusion assays, broth micro-dilution assays and time-kill kinetics studies against five microbial species, including Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). The formation of G-AgNPs is a promising novel approach to enhancing the biological activeness of silver nanoparticles, and to increase the water solubility of garcinol which creates a broad range of therapeutic applications.

• Advances in nano research
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• v.4 no.3
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• pp.157-165
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• 2016

The photocatalytic (PC) activity of anatase titania nanoparticles can be improved through codoping with transition metals and nitrogen. In addition, the PC activity can also be improved by creating monodisperse, mesoporous nanoparticles of titania. The question naturally arose as to whether combining these two characteristics would result in further improvement in the PC activity or not. Herein, we describe the synthesis and photocatalytic characteristics of codoped, monodisperse anatase titania. The transition metals tested in the polydisperse and the monodisperse forms were Mn, Co, Ni, and Cu. In each case, it was found that the monodisperse version had a higher PC activity compared to the corresponding polydisperse version.

• Advances in nano research
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• v.13 no.5
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• pp.437-451
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• 2022

Synthesis approaches usually affect the physical and chemical properties of ferrites. This helps ferrite materials to design them for desired applications. Some of these methods are mechanical milling, ultrasonic method, micro-emulsion, co-precipitation, thermal decomposition, hydrothermal, microwave-assisted, sol-gel, etc. These methods are extensively reviewed by taking example of ZnFe₂O₄. These methods also affect the microstructure and local structure of ferrite which ultimately affect the physical and chemical properties of ferrites. Various spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Ultra Violet-Visible spectroscopy, Mossbauer spectroscopy, extended x-ray absorption fine structure, and electron paramagnetic resonance are found helpful to reveal this information. Hence, the basic principle and the usefulness of these techniques to find out appropriate information in ZnFe₂O₄ nanoparticles is elaborated in this review.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.3
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• pp.238-245
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• 2017

Mg-Ni nanoparticles were synthesized by a physical vapor condensation method (DC arc-discharge) in a mixture of argon and hydrogen atmosphere, using compressed mixture of micro powders as the raw materials. The crystal phases, morphology, and microstructures of nanoparticles were analyzed by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). It was found that the intermetallic compounds of $Mg_2Ni$ and $Mg_2Ni$ formed with existence of phases of Mg, Ni, and MgO in Mg-Ni nanoparticles. After one cycle of hydrogen absorption/desorption process (activation treatment), Mg-Ni nanoparticles exhibited excellent hydrogen absorption properties. $Mg_2Ni$ phase became the main phase by aphase transformation during the hydrogen treatments. The phenomenon of refinement of grain size in the nanoparticle was also observed after the hydrogen absorption/desorption processes, which was attributed to the effect of volume expansion/shrinkage and subsequent break of nanoparticles. Maximum hydrogen absorption contents are 1.75, 2.21 and 2.77 wt.% at 523, 573 and 623 K, respectively.

• Journal of Periodontal and Implant Science
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• v.53 no.5
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• pp.321-335
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• 2023

Purpose: The aim of this study was to investigate the efficacy of photo-crosslinked gelatin methacryloyl (GelMa) hydrogel containing calcium phosphate nanoparticles (CNp) when applying different fabrication methods for bone regeneration. Methods: Four circular defects were created in the calvaria of 10 rabbits. Each defect was randomly allocated to the following study groups: 1) the sham control group, 2) the GelMa group (defect filled with crosslinked GelMa hydrogel), 3) the CNp-GelMa group (GelMa hydrogel crosslinked with nanoparticles), and 4) the CNp+GelMa group (crosslinked GelMa loaded with nanoparticles). At 2, 4, and 8 weeks, samples were harvested, and histological and micro-computed tomography analyses were performed. Results: Histomorphometric analysis showed that the CNp-GelMa and CNp+GelMa groups at 2 weeks had significantly greater total augmented areas than the control group (P<0.05). The greatest new bone area was observed in the CNp-GelMa group, but without statistical significance (P>0.05). Crosslinked GelMa hydrogel with nanoparticles exhibited good biocompatibility with a minimal inflammatory reaction. Conclusions: There was no difference in the efficacy of bone regeneration according to the synthesized method of photo-crosslinked GelMa hydrogel with nanoparticles. However, these materials could remain within a bone defect up to 2 weeks and showed good biocompatibility with little inflammatory response. Further improvement in mechanical properties and resistance to enzymatic degradation would be needed for the clinical application.

• Toxicological Research
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• v.31 no.2
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• pp.157-163
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• 2015

Nanotechnology has advanced at an extremely rapid pace over the past several years in numerous fields of research. However, the uptake of nanoparticles (NPs) into the body after administration through various routes may pose a risk to human health. In this study, we investigated the potential ocular toxicity of 20-nm, negatively- charged zinc oxide (ZnO) NPs in rats using micro-computed tomography (micro-CT) and histopathological assessment. Animals were divided into four groups as control group, ZnO NPs treatment group (500 mg/kg/day), control recovery group, and ZnO NPs treatment and recovery group. Ocular samples were prepared from animals treated for 90 days (10 males and 10 females, respectively) and from recovery animals (5 males and 5 females, respectively) sacrificed at 14 days after final treatment and were compared to age-matched control animals. Micro-CT analyses represented the deposition and distribution of foreign materials in the eyes of rats treated with ZnO NPs, whereas control animals showed no such findings. X-ray fluorescence spectrometry and energy dispersive spectrometry showed the intraocular foreign materials as zinc in treated rats, whereas control animals showed no zinc signal. Histopathological examination revealed the retinopathy in the eyes of rats treated with ZnO NPs. Neuronal nuclei expression was decreased in neurons of the ganglion cell layer of animals treated with ZnO NPs compared to the control group. Taken together, treatment with 20-nm, negatively-charged ZnO NPs increased retinopathy, associated with local distribution of them in ocular lesions.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.19-19
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• 2005

This paper reports a novel magnetic force-based microfluidic immunoassay using microbeads and magnetic nanoparticles. The magnetic force-based immunoassay was devised first and successfully applied to detect the rabbit IgG as the model analyte of microfluidic sandwich immunoassay. The microchannels were fabricated by poly(dimethysiloxane) (PDMS) molding processes and bonded on a slide glass by plasma treatment. At the part of the inlet, sample solution was hydrodynamically focused. The focused microbeads of sample solution were flowed through the 150 ${\mu}m$ width channel of outlet. However, when the microbeads are conjugated with the superparamagnetic nanoparticles under the applied magnetic fields, they will switch their flow path and flow through the 95 ${\mu}m$ width channel of outlet. The movements of microbeads conjugated with magnetic nanoparticles were demonstrated by magnetic field $gradients.^{1)}$ High magnetic field gradients using micro electromagnets could be applied to this detection method for high sensitivity and lower detection limit. In addition, the multiplexed $immunoassay^{2)}$ using an encoded microbead which is immobilized with a certain antibody could be possible using this detection principle.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.53-58
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• 2013

Superhydrophobic $SiO_2$ layers with a micro-nano hierarchical surface structure were prepared. $SiO_2$ layers deposited via an electrospray method combined with a sol-gel chemical route were rough on the microscale. Au particles were decorated on the surface of the microscale-rough $SiO_2$ layers by use of the photo-reduction process with different intensities ($0.11-1.9mW/cm^2$) and illumination times (60-240 sec) of ultraviolet light. With the aid of nanoscale Au nanoparticles, this consequently resulted in a micro-nano hierarchical surface structure. Subsequent fluorination treatment with a solution containing trichloro(1H,2H,2H,2H-perfluorooctyl)silane fluorinated the hierarchical $SiO_2$ layers. The change in surface roughness factor was in good agreement with that observed for the water contact angle, where the surface roughness factor developed as a measure needed to evaluate the degree of surface roughness. The resulting $SiO_2$ layers revealed excellent repellency toward various liquid droplets with different surface tensions ranging from 46 to 72.3 mN/m. Especially, the micro-nano hierarchical surface created at an illumination intensity of $0.11mW/cm^2$ and illumination time of 60 sec showed the largest water contact angle of $170^{\circ}$. Based on the Cassie-Baxter and Young-Dupre equations, the surface fraction and work of adhesion for the micronano hierarchical $SiO_2$ layers were evaluated. The work of adhesion was estimated to be less than $3{\times}10^{-3}N/m$ for all the liquid droplets. This exceptionally small work of adhesion is likely to be responsible for the strong repellency of the liquids to the micro-nano hierarchical $SiO_2$ layers.