• Nano
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• 제13권12호
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• pp.1850145.1-1850145.8
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• 2018

In this study, a double-solvent radiation method is proposed to prepare silver nanoparticles in the pores of metal-organic framework MIL-101(Cr). The results reveal that well-dispersed silver nanoparticles with a diameter of about 2 nm were successfully fabricated in the cages of monodisperse octahedral MIL-101(Cr) with a particle size of about 400 nm. The structure of MIL-101(Cr) was not destroyed during the chemical treatment and irradiation. The resulting Ag/MIL-101 exhibits excellent catalytic performance for the reduction of 4-nitrophenol. This method can be extended to prepare other single or bimetallic components inside porous materials.

• 청정기술
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• 제28권4호
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• pp.285-292
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• 2022

대기 오염의 주요 원인인 휘발성유기화합물(VOCs)의 배출을 저감 하기 위한 방법으로 주로 활성탄 흡착탑이 활용되고 있다. 하지만 활성탄의 짧은 수명과 잦은 교체 주기의 단점이 있어 이를 극복하기 위한 다양한 기술이 개발되고 있으며, 광촉매-활성탄 복합체는 이러한 활성탄의 단점을 극복할 수 있는 방법임을 입증하였다. 광촉매-활성탄 복합체는 활성탄 표면에 금속산화물 광촉매를 코팅하여 광촉매 효과와 활성탄의 흡착능력 효과를 동시에 확보할 수 있는 휘발성유기화합물 저감 물질이다. 미세유체공정을 이용하여 ZnO, 은(Ag) 나노입자를 동시에 합성한 후 실시간으로 ZnO와 은(Ag) 나노입자 용액을 활성탄이 채워진 충진층 반응기에 주입하여 Ag-ZnO 활성탄 복합체를 합성하였다. 합성 반응시간에 따른 광촉매 복합체의 증착양을 분석했으며, 다양한 분석 방법을 통해 광촉매가 활성탄의 기공을 막지 않고 활성탄 표면에 선택적으로 증착 되었음을 확인하였다. 톨루엔 가스백 시험과 흡착 파괴시간 시험을 통해 광촉매-활성탄 복합체가 순수한 활성탄보다 우수한 저감 효과와 지속성을 가지는 것을 확인하였다. 본 연구를 통해 개발된 공정은 광촉매-활성탄 복합체를 효율적으로 생산할 수 있는 방법으로 대량 생산을 위한 스케일 업 공정을 통해 국내의 VOCs 저감 물질 가격 경쟁력을 높일 수 있을 것으로 사료된다.

• 생태와환경
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• 제42권1호
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• pp.75-84
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• 2009

여러 가지 은나노물질(SNPs)의 M. aeruginosa 생장에 대한 영향을 실내, 외 실험을 통해 조사하였다. 제조된 4가지 SNPs는 농도 $200mg\;L^-1$, 입자크기 $20{\sim}40nm$, 갈색 Ag로서의 수용액이었으며 이 용액들을 각각 실험에 사용하였다. SNPs는 unicellular M. aeruginosa에 대하여 0.01, $0.1mg\;L^-1$의 첨가농도에서 각각 99.4%, 99.9%의 조류 생장억제 효과를 나타냈으며, colonial M. aeruginosa에 대하여는 여러 가지 농도 중 $1mg\;L^-1$의 농도에서 가장 높은 생장억제 효과(98.5%)를 나타냈다. 더욱이 부영양화한 현장에서 SNPs를 첨가한 enclosure 실험을 통해 M. aeruginosa에 대한 선택적 제어 가능성이 시사되었다. 본 연구를 통해서 향후 SNPs를 더욱 보완하면 M. aeruginosa를 비롯한 유해 남조의 선택적 제어에 좀더 효과적일 것으로 판단된다.

• 생명과학회지
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• 제31권9호
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• pp.862-872
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• 2021

최근 생물의학 분야에서의 광범위한 응용 가능성에 의하여 식물이나 미생물을 이용한 은(Ag), 금(Au), 백금(Pt), 세륨(Ce), 아연(Zn), 구리(Cu) 등의 금속 나노물질 합성에 관한 연구가 주목받고 있다. 식물은 플라보노이드, 알칼로이드, 사포닌, 스테로이드 탄닌과 각종 영양 성분과 같은 생리 활성 물질을 풍부하게 가지고 있으며, 유사하게 미생물들도 단백질과 같은 생리활성 대사산물이나 색소, 항생제 및 산과 같은 가치가 있는 화학물질을 분비한다. 최근 보고된 바에 의하면, 나노입자의 생체 합성은 무해한 방법일 뿐만 아니라 항균, 항진균, 세포 증식 억제 및 항플라스모디아 활성과 같은 생물의학 분야로서의 적용에 주요한 후보로 여겨진다. 나노입자의 이러한 생리 활성은 농도에 의존적이며, 나노입자의 모양과 크기에도 따라 달라질 수 있다. 미생물과 식물은 나노입자의 친환경적합성에 사용되는 대사산물이나 화학물질 등의 훌륭한 공급원으로서 생물 의학 분야에서 유용하게 사용된다. 미생물 또는 식물 원료를 사용하여 합성된 나노입자는 화학적인 방법으로 합성된 나노입자보다 더 낮은 독성을 나타낸다. 본 리뷰논문에서는 미생물이나 식물과 같은 생물학적 재료를 이용한 나노입자의 합성과, 합성에 사용되는 다양한 기술의 특성 및 나노입자의 항균 분야에서의 적용에 대하여 중점적으로 서술하였다.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1179-1184
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• 2008

Commercial nanometer sized silver is widely used for its antibacterial effect; however, nanoparticles may also have ecotoxicological effects after being discharged into water. Nanometer sized silver can flow into aquatic environments, where it can exert a variety of physiologically effects in living organisms, including fish. The present study aimed to investigate the effect of nanometer sized silver on the development of zebrafish embryos, analyze the properties of commercial nanometer sized silver and define the toxicity relationship between embryogenesis and hatched flies. The commercial nanometer sized silver was analyzed in the $Ag^+$ ion form. The hatch rate decreased in the nano-silver exposed groups (10 and 20 ppt); furthermore, the hatched flies had an abnormal notochord, weak heart beat, damaged eyes and curved tail. The expression of the Sel N1 gene decreased in the nano-silver exposed groups, and the catalase activities of the exposed groups increased relative to those in the control group. Therefore, the $Ag^+$ ions in commercial nanometer sized silver could accumulate in aquatic environments and seriously damage the development of zebrafish embryos.

• 한국환경보건학회지
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• 제41권1호
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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.

• Bulletin of the Korean Chemical Society
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• 제29권10호
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• pp.1983-1987
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• 2008

This study demonstrates the electrochemical conversion of the synthetic procedure of monolayer-protected clusters using a thin toluene layer over an edge plane pyrolytic graphite electrode. A thin toluene layer with a thickness of 0.31 mm was coated over the electrode and an immiscible liquid/liquid water/toluene interface was introduced. The transfer of the tetrachloroaurate ($AuCl_4^-$) ions into the toluene layer interposed between the aqueous solution and the electrode surface was electrochemically monitored. The $AuCl_4^-$ ions initially could not move through into the toluene layer, showing no reduction wave, but, in the presence of the phase transfer reagent, tetraoctylammonium bromide (TOABr), a cathodic wave at 0.23 V vs. Ag/AgCl was observed, indicating the reduction of the transferred $AuCl_4^-$ ions in the toluene layer. In the presence of dodecanethiol together with TOABr, a self-assembled monolayer was formed over the electro-deposited metallic gold surface. The E-SEM image of the surface indicates the formation of a highly porous metallic gold surface, rather than individual nanoparticles, over the EPG electrode.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.169-175
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• 2018

Cu-Salen complex was prepared and attached into chitosan (Cs) polymer backbone. Nanocomposite of the synthesized polymer was prepared with functionalized carbon nano-particles (Cs-Cu-sal/C) to modify the electrode surface. The surface morphology of (Cs-Cu-sal/C) nanocomposite film showed a homogeneous distribution of carbon nanoparticles within the polymeric matrix. The cyclic voltammogram of the modified electrode exhibited a redox behavior at -0.1 V vs. Ag/AgCl (3 M KCl) in 0.1 M PB (pH 7) and showed an excellent hydrogen peroxide reduction activity. The Cs-Cu-sal/C electrode displays a linear response from $5{\times}10^{-6}$ to $5{\times}10^{-4}M$, with a correlation coefficient of 0.993 and detection limit of $0.9{\mu}M$ (at S/N = 3). The sensitivity of the electrode was found to be $0.356{\mu}A\;{\mu}M^{-1}\;cm^{-2}$.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3723-3729
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• 2010

We investigated the high-excitation voltage cathodoluminescence (CL) performance of blue light-emitting (ZnS:Ag,Al,Cl) and green light-emitting (ZnS:Cu,Al) phosphors coated with metal oxides ($SiO_2$, $Al_2O_3$, and MgO). Hydrolysis of the metal oxide precursors tetraethoxysilane, aluminum isopropoxide, and magnesium nitrate, with subsequent heat annealing at $400^{\circ}C$, produced $SiO_2$ nanoparticles, an $Al_2O_3$ thin film, and MgO scale-type film, respectively, on the surface of the phosphors. Effects of the phosphor surface coatings on CL intensities and aging behavior of the phosphors were assessed using an accelerating voltage of 12 kV. The MgO thick film coverage exhibited less reduction in initial CL intensity and was most effective in improving aging degradation. Phosphors treated with a low concentration of magnesium nitrate maintained their initial CL intensities without aging degradation for 2000 s. In contrast, the $SiO_2$ and the $Al_2O_3$ coverages were ineffective in improving aging degradation.

• 센서학회지
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• 제31권5호
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• pp.312-317
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• 2022

Piezoelectric energy harvesting has attracted increasing attention over the last decade as a means for generating sustainable and long-lasting energy from wasted mechanical energy. To develop self-powered wearable devices, piezoelectric materials should be flexible, stretchable, and bio-eco-friendly. This study proposed the fabrication of stretchable piezoelectric composites via dispersing perovskite-structured BaTiO₃ nanoparticles inside an Ecoflex polymeric matrix. In particular, the stretchable piezoelectric sensor array was fabricated via a simple and cost-effective spin-coating process by exploiting the piezoelectric composite comprising of BaTiO₃ nanoparticles, Ecoflex matrix, and stretchable Ag coated textile electrodes. The fabricated sensor generated an output voltage of ~4.3 V under repeated compressing deformations. Moreover, the piezoelectric sensor array exhibited robust mechanical stability during mechanical pushing of ~5,000 cycles. Finite element method with multiphysics COMSOL simulation program was employed to support the experimental output performance of the fabricated device. Finally, the stretchable piezoelectric sensor array can be used as a self-powered touch sensor that can effectively detect and distinguish mechanical stimuli, such as pressing by a human finger. The fabricated sensor demonstrated potential to be used in a stretchable, lead-free, and scalable piezoelectric sensor array.