• 제목, 요약, 키워드: Ag nanoparticles

검색결과 314건 처리시간 0.059초

Synthesis of Ni-Ag Core-shell Nanoparticles by Polyol process and Microemulsion Process

  • Nguyen, Ngoc Anh Thu;Park, Joseph G.;Kim, Sang-Hern
    • Bulletin of the Korean Chemical Society
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    • v.34 no.10
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    • pp.2865-2870
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    • 2013
  • Ni-Ag core-shell nanoparticles were synthesized by polyol process and microemulsion technique successfully. In the polyol process, a chemical reduction method for preparing highly dispersed pure nickel and Ag shell formation have been reported. The approach involved the control of reaction temperature and reaction time in presence of organic solvent (ethylene glycol) as a reducing agent for Ag cation with poly(vinyl-pyrrolidone) (PVP. Mw = 40000) as a capping agent. In microemulsion method, the emulsion was prepared by water/cetyltrimetylammonium bromide (CTAB)/cyclohexane. The size of microemulsion droplet was determined by the molar ratio of water to surfactant (${\omega}_o$). The core-shell formation along with the change in structural phase and stability against oxidation at high temperature heat treatments of nanoparticles were investigated by X-ray diffraction and TEM analysis. Under optimum conditions the polyol process gives the Ni-Ag core-shell structures with 13 nm Ni core covered with 3 nm Ag shell, while the microemulsion method gives Ni core diameter of 8 nm with Ag shell of thickness 6 nm. The synthesized Ni-Ag core-shell nanoparticles were stable against oxidation up to $300^{\circ}C$.

Synthesis of Cysteine Capped Silver Nanoparticles by Electrochemically Active Biofilm and their Antibacterial Activities

  • Khan, Mohammad Mansoob;Kalathil, Shafeer;Lee, Jin-Tae;Cho, Moo-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.33 no.8
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    • pp.2592-2596
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    • 2012
  • Cysteine capped silver nanoparticles (Cys-AgNPs) have been synthesized by employing electrochemically active biofilm (EAB), $AgNO_3$ as precursor and sodium acetate as electron donor in aqueous solution at $30^{\circ}C$. Cys-AgNPs of 5-10 nm were synthesized and characterized by UV-Vis, FT-IR, XRD and TEM. Capping of the silver nanoparticles with cysteine provides stability to nanoparticles by a thiolate bond between the amino acid and the nanoparticle surface and hydrogen bonding among the Cys-AgNPs. In addition, the antibacterial effects of as-synthesized Cys-AgNPs have been tested against two pathogenic bacteria Escherichia coli (O157:H7) and Pseudomonas aeruginosa (PAO1). The results demonstrate that the as-synthesized Cys-AgNPs can proficiently inhibit the growth and multiplication of E. coli and P. aeruginosa.

Controllable Biogenic Synthesis of Intracellular Silver/Silver Chloride Nanoparticles by Meyerozyma guilliermondii KX008616

  • Alamri, Saad A.M.;Hashem, Mohamed;Nafady, Nivien A.;Sayed, Mahmoud A.;Alshehri, Ali M.;El-Shaboury, Gamal A.
    • Journal of Microbiology and Biotechnology
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    • v.28 no.6
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    • pp.917-930
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    • 2018
  • Intracellular synthesis of silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Meyerozyma guilliermondii KX008616 is reported under aerobic and anaerobic conditions for the first time. The biogenic synthesis of Ag-NP types has been proposed as an easy and cost-effective alternative for various biomedical applications. The interaction of nanoparticles with ethanol production was mentioned. The purified biogenic Ag/AgCl-nanoparticles were characterized by different spectroscopic and microscopic approaches. The purified nanoparticles exhibited a surface plasmon resonance band at 419 and 415 nm, confirming the formation of Ag/AgCl-NPs under aerobic and anaerobic conditions, respectively. The planes of the cubic crystalline phase of the Ag/AgCl-NPs were confirmed by X-ray diffraction. Fourier-transform infrared spectra showed the interactions between the yeast cell constituents and silver ions to form the biogenic Ag/AgCl-NPs. The intracellular Ag/AgCl-NPs synthesized under aerobic condition were homogenous and spherical in shape, with an approximate particle size of 2.5-30nm as denoted by the transmission electron microscopy (TEM). The reaction mixture was optimized by varying reaction parameters, including temperature and pH. Analysis of ultrathin sections of yeast cells by TEM indicated that the biogenic nanoparticles were formed as clusters, known as nanoaggregates, in the cytoplasm or in the inner and outer regions of the cell wall. The study recommends using the biomass of yeast that is used in industrial or fermentation purposes to produce Ag/AgCl-NPs as associated by-products to maximize benefit and to reduce the production cost.

Poly(ethylenimine)-Stabilized Hollow Gold-Silver Bimetallic Nanoparticles: Fabrication and Catalytic Application

  • Shin, Kuan-Soo;Kim, Ji-Hoon;Kim, In-Hyun;Kim, Kwan
    • Bulletin of the Korean Chemical Society
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    • v.33 no.3
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    • pp.906-910
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    • 2012
  • Hollow gold-silver bimetallic nanoparticles (AuAg-HNPs) have been synthesized and their optical and structural properties were characterized. Initially Ag nanoparticles (Ag-NPs) were prepared using poly(ethylenimine) (PEI) as a reducing and a stabilizing agent simultaneously. AuAg-HNPs could then be synthesized via galvanic replacement reaction in a PEI aqueous solution by reacting sacrificial Ag template with a precursor compound of Au, i.e., $HAuCl_4$. Due to the presence of abundant amine functional groups in PEI, which could act as the dissolving ligand for AgCl, the precipitation problem of $Ag^+$ in the presence of Cl from $HAuCl_4$ salt was avoided. On this basis, the relatively high concentrations of $HAuCl_4$ and PEI-stabilized Ag nanoparticles could be used for the fabrication of AuAg-HNPs. Because of their increased surface areas and reduced densities, the AuAg-HNPs were expected and confirmed to outperform their solid counterparts in applications such as catalysis for the reduction of 4-nitrophenol in the presence of $NaBH_4$.

3차원 FDTD Simulation을 이용한 자기조립된 Ag 나노입자의 국소표면플라즈몬공명 상호작용 현상 연구 (Localized Surface Plasmon Resonance Coupling in Self-Assembled Ag Nanoparticles by Using 3-Dimensional FDTD Simulation)

  • 이경민;윤순길;정종율
    • 한국재료학회지
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    • v.24 no.8
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    • pp.417-422
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    • 2014
  • In this study, we investigated localized surface plasmon resonance and the related coupling phenomena with respect to various geometric parameters of Ag nanoparticles, including the size and inter-particle distance. The plasmon resonances of Ag nanoparticles were studied using three-dimensional finite difference time domain(FDTD) calculations. From the FDTD calculations, we discovered the existence of a symmetric and an anti-symmetric plasmon coupling modes in the coupled Ag nanoparticles. The dependence of the resonance wavelength with respect to the inter-particle distance was also investigated, revealing that the anti-symmetric mode is more closely correlated with the inter-particle distance of the Ag nanoparticles than the symmetric mode. We also found that higher order resonance modes are appeared in the extinction spectrum for closely spaced Ag nanoparticles. Plasmon resonance calculations for the Ag particles coated with a $SiO_2$ layer showed enhanced plasmon coupling due to the strengthened plasmon resonance, suggesting that the inter-particle distance of the Ag nanoparticles can be estimated by measuring the transmission and absorption spectra with the plasmon resonance of symmetric and anti-symmetric localized surface plasmons.

올레핀/파라핀 분리용 AgNO3 전구체를 활용한 poly(ethylene oxide)/Ag nanoparticles/p-benzoquinone 복합체 분리막 제조 (Fabrication of Poly(ethylene oxide)/Ag Nanoparticles/p-benzoquinone Composite Membrane Using AgNO3 Precursor for Olefin/Paraffin Separation)

  • 김민수;강상욱
    • 멤브레인
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    • v.28 no.4
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    • pp.260-264
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    • 2018
  • 올레핀/파라핀 분리를 위해 poly(ethylene oxide)(PEO)/Ag nanoparticles (AgNPs)(전구체: $AgBF_4$)/p-benzoquinone (p-BQ) 복합막이 제조되었으며, 이 복합체 분리막의 성능은 100시간까지 선택도 10과 투과도 15 GPU로 유지되는 것이 관찰되었다. 분리막의 성능이 100시간까지 유지할 수 있었던 이유는 p-BQ의 첨가로 인해 Ag ion이 안정적으로 Ag nanoparticles로 형성될 수 있었을 뿐더러 전자수용체인 p-BQ으로 인해 표면이 부분 양극성화 되어 올레핀 운반체로서 역할을 성공적으로 수행한 결과라 생각되었다. 본 연구에서는 Ag nanoparticles의 전구체로 사용된 $AgBF_4$의 가격이 고가이기 때문에 가격 측면에서 유리한 $AgNO_3$ Ag nanoparticles의 전구체로 사용하여 실험을 진행하였다. 그 결과로서 $AgNO_3$의 경우에는 앞선 $AgBF_4$과는 다르게 안정적으로 은 나노입자가 형성되지 못하고 이로 인하여 좋은 성능을 내지 못하는 것으로 분석되었다.

목련잎 추출액을 이용한 Au Core-Ag Shell 합금 나노입자의 생물학적 합성 (Biological Synthesis of Au Core-Ag Shell Bimetallic Nanoparticles Using Magnolia kobus Leaf Extract)

  • 송재용;김범수
    • Korean Chemical Engineering Research
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    • v.48 no.1
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    • pp.98-102
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    • 2010
  • 목련잎 추출액을 이용하여 Au core-Ag shell 합금 나노입자를 합성하였다. 환원제인 식물잎 추출액을 먼저 $HAuCl_4$ 용액과 반응시키고 다음에 $AgNO_3$ 용액과 반응시켜 금 seed와 은 shell을 형성시켰다. 반응시간에 따른 UV-visible spectroscopy의 변화를 모니터링하여 합금 나노입자의 형성을 관찰하였다. 합성된 합금 나노입자를 transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), X-ray photoelectron spectroscopy(XPS) 등으로 특성화 하였다. TEM image로부터 관찰된 합금 나노입자는 삼각형, 오각형, 육각형 등의 평판과 구 구조의 혼합물이었다. EDS와 XPS 분석으로부터 결정된 금/은 합금 나노입자의 원자 은 함량은 각각 34와 65 wt%로 Au core-Ag shell 나노구조가 형성되었음을 알 수 있었다. 이러한 core-shell 형태의 나노구조는 표면 강화 라만 분광 및 생물분자의 고감도 검출 등에 잠재적인 응용이 기대된다.

근적외선 센서를 위한 Ag2Se 나노 입자 합성 및 광전기적 특성 (Synthesis and Optoelectronic Characteristics of Ag2Se Nanoparticle for NIR Sensor Application)

  • 장재원
    • 센서학회지
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    • v.28 no.4
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    • pp.266-269
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    • 2019
  • In this study, $Ag_2Se$ nanoparticles were synthesized by employing the colloidal method. The synthesized $Ag_2Se$ nanocrystals were spherical in shape with a diameter of approximately 4 nm and had high crystallinity. These attributes of $Ag_2Se$ nanocrystals were determined through images obtained from a high resolution transmission electron microscope. Thin films comprising the synthesized $Ag_2Se$ nanoparticles had an optical band gap of 1.5 eV. Furthermore, fabricated NIR sensors comprising $Ag_2Se$ nanoparticles exhibited a high detectivity of $5.5{\times}10^9$ Jones (above $1{\times}10^9$) at room temperature, leading to low power consumption

Nano-sized Effect on the Magnetic Properties of Ag Clusters

  • Jo, Y.;Jung, M.H.;Kyum, M.C.;Park, K.H.;Kim, Y.N.
    • Journal of Magnetics
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    • v.11 no.4
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    • pp.160-163
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    • 2006
  • We have prepared crystalline Ag nanoparticles with an average size of 4 nm in diameter by using an inductively coupled plasma reactor equipped with the liquid nitrogen cooling system. Our magnetic data show that the nano-sized effect of Ag nanoparticles on the magnetic properties is ferromagnetic, instead of a diamagnetic component of the Ag bulk and a superparamagnetic component of magnetic nanoparticles. We have also studied the magnetic properties of Ag-Cu nanocomposites with an opposite concentration profile between surface and core. These comparisons indicate that the ferromagnetic component strongly depends on the surface of Ag nanoparticles, while the paramagnetic component is strongly affected by the outer oxide layer, with the background of a diamagnetic component from the core of Ag.

은 나노입자를 함유한 폴리우레탄 나노섬유 매트의 제조 (Preparation of Polyurethane Nanofiber Mats Containing Silver Nanoparticles)

  • 김문희;전현정;홍지혜;정은환;육지호
    • 한국섬유공학회지
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    • v.43 no.1
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    • pp.1-6
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    • 2006
  • Poly(urethane)(PU) nanofibers containing silver nanoparticles were prepared via a simple one-step method. PU was dissolved in DMAc/THF(7/3 w/w) with a small amount of $AgNO_3.Ag^+$ ions in the PU solution were reduced by DMAc into Ag nanoparticles, which was confirmed by UV-vis spectroscopy and TEM analysis. DMAc was used as a solvent for PU as well as a reducing agent for the Ag+ ions. The resulting solutions were directly electrospun into PU nanofibers. The Ag nanoparticles were all sphere shaped and evenly distributed in the PU nanofibers. The average sizes of Ag nanoparticles in PU nanofibers electro spun with 0.2 and 0.5 wt% $AgNO_3$ were 3.6 and 4.0 nm, respectively.