• Title, Summary, Keyword: Ag nanoparticles

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Antifungal Effects of Silver Phytonanoparticles from Yucca shilerifera Against Strawberry Soil-Borne Pathogens: Fusarium solani and Macrophomina phaseolina

  • Ruiz-Romero, Paola;Valdez-Salas, Benjamin;Gonzalez-Mendoza, Daniel;Mendez-Trujillo, Vianey
    • Mycobiology
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    • v.46 no.1
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    • pp.47-51
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    • 2018
  • In the present study, the characterization and properties of silver nanoparticles from Yucca shilerifera leaf extract (AgNPs) were investigated using UV-visible spectroscopic techniques, zeta potential, and dynamic light scattering. The UV-visible spectroscopic analysis showed the absorbance peaked at 460 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 729 nm with lower stability (195.1 mV). Additionally, our dates revealed that AgNPs showed broad spectrum antagonism ($p{\leq}.05$) against Fusarium solani (83.05%) and Macrophomina phaseolina (67.05%) when compared to the control after nine days of incubation. Finally, AgNPs from leaf extracts of Y. shilerifera may be used as an agent of biocontrol of microorganism of importance. However, further studies will be needed to fully understand the agronanotechnological potentialities of AgNPs from Yucca schidigera.

Preparation of Poly (Vinyl Alcohol) Nanofibers Containing Silver Nanoparticles by Gamma-ray Irradiation

  • Kim, Yun-Hye;Shin, Junwha;Youn, Min-Ho;An, Sung-Jun;Lim, Youn-Mook;Gwon, Hui-Jeong;Nho, Young-Chang
    • Journal of Radiation Industry
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    • v.2 no.3
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    • pp.129-133
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    • 2008
  • PVA nanofibers containing silver nanoparticles were prepared by two methods. The first method was electrospinning of irradiated solution. The prepared $PVA/AgNO_3$ solution was irradiated by gamma-rays. And then the irradiated solution was electrospun. The second method was irradiation of electrospun nanofibers. Nanofibers prepared by electrospinning of unirradiated $PVA/AgNO_3$ solution. The morphology of the nanofibers was observed with a SEM, TEM. When the irradiated $PVA/AgNO_3$ solution were electrospun, the average size of the Ag nanoparticles was increased, but their number was decreased.

Effects of Water Chemistry on Aggregation and Soil Adsorption of Silver Nanoparticles

  • Bae, Sujin;Hwang, Yu Sik;Lee, Yong-Ju;Lee, Sung-Kyu
    • Environmental health and toxicology
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    • v.28
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    • pp.6.1-6.7
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    • 2013
  • Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

Transport of PVP-coated Silver Nanoparticles in Saturated Porous Media (포화된 다공성매체에서 PVP-코팅된 은나노입자의 이동성 연구)

  • Bae, Sujin;Jang, Min-Hee;Lee, Woo Chun;Park, Jae-Woo;Hwang, Yu Sik
    • Journal of Soil and Groundwater Environment
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    • v.21 no.1
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    • pp.104-110
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    • 2016
  • The transport of silver nanoparticles (AgNPs) was investigated through a column packed with sand. A series of column experiments were carried out to evaluate the effect of ionic strength (IS), pH, electrolyte type and clay mineral on mobility of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs). The deposition of PVP-AgNPs was increased with increasing solution ionic strength and decreasing pH. Furthermore, the depositon of PVP-AgNPs was affected by the electrolyte type (NaCl vs. NaNO3) and was shown to be greater at NaNO3 solution. Also, the transport of PVP-AgNPs was greatly increased after the pre-deposition of clay particles on sand. Our results suggest that various environmental factors can influence the mobility of PVP-AgNPs in soil-groundwater systems and should be carefully considered in assessing their environmental risks.

Localized Surface-Plasmon Resonance of Ag Nanoparticles Produced by Laser Dewetting to Improve the Performance of a Sensitized TiO2 Solar Cell (레이저 Dewetting에 의해 형성된 은 나노입자의 국소 표면플라즈몬 공명을 이용한 감응형 TiO2 태양전지 성능 향상)

  • Lee, Jeeyoung;Lee, Myeongkyu
    • Korean Journal of Optics and Photonics
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    • v.29 no.5
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    • pp.215-219
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    • 2018
  • In this paper we show that the localized surface-plasmon resonance of Ag nanoparticles produced by laser dewetting can be effectively utilized for improving the photocurrent and efficiency of a dye-sensitized $TiO_2$ solar cell. An Ag thin film deposited on a conducting glass substrate was dewetted into nanoparticles by a pulsed laser. A dye-sensitized $TiO_2$ solar cell fabricated on this substrate containing the Ag nanoparticles exhibited improved photovoltaic performance, compared to a reference cell. This is attributed to the increased light trapping that arises from the localized surface-plasmon resonance of the dewetted Ag nanoparticles.

Direct-Patternable SnO2 Thin Films Incorporated with Conducting Nanostructure Materials (직접패턴형 SnO2 박막의 전도성 나노구조체 첨가연구)

  • Kim, Hyun-Cheol;Park, Hyung-Ho
    • Korean Journal of Materials Research
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    • v.20 no.10
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    • pp.513-517
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    • 2010
  • There have been many efforts to modify and improve the properties of functional thin films by hybridization with nano-sized materials. For the fabrication of electronic circuits, micro-patterning is a commonly used process. For photochemical metal-organic deposition, photoresist and dry etching are not necessary for microscale patterning. We obtained direct-patternable $SnO_2$ thin films using a photosensitive solution containing Ag nanoparticles and/or multi-wall carbon nanotubes (MWNTs). The optical transmittance of direct-patternable $SnO_2$ thin films decreased with introduction of nanomaterials due to optical absorption and optical scattering by Ag nanoparticles and MWNTs, respectively. The crystallinity of the $SnO_2$ thin films was not much affected by an incorporation of Ag nanoparticles and MWNTs. In the case of mixed incorporation with Ag nanoparticles and MWNTs, the sheet resistance of $SnO_2$ thin films decreased relative to incorporation of either single component. Valence band spectral analyses of the nano-hybridized $SnO_2$ thin films showed a relation between band structural change and electrical resistance. Direct-patterning of $SnO_2$ hybrid films with a line-width of 30 ${\mu}m$ was successfully performed without photoresist or dry etching. These results suggest that a micro-patterned system can be simply fabricated, and the electrical properties of $SnO_2$ films can be improved by incorporating Ag nanoparticles and MWNTs.

The Stability of Citrate-capped Silver Nanoparticles in Isotonic Glycerol Solution for Intravenous Injection (글리세롤을 이용한 구연산캡핑 은나노입자의 정맥주사용 현탁액 조제 및 안정성)

  • Lee, Yeon-Jin;Park, Kwang-Sik
    • YAKHAK HOEJI
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    • v.56 no.2
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    • pp.74-79
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    • 2012
  • Citrate-capped silver nanoparticles (AgNPs) are widely used in industry, consumer products and medical appliances. However, information on the toxicity, environmental fate and toxicokinetics are not enough. In this study, stability of citrate-capped AgNPs was investigated using different types of isotonic solution, which is important in the toxicokinetic study by the exposure route of intravenous injection. Size, morphology, zeta potential and ion formation were investigated in isotonic solutions for the physico-chemical characterization of AgNPs. Aggregation and precipitation of AgNPs were observed in saline or phosphate-buffered saline while they were stable without precipitation in 2% glycerol of isotonic solution. The average size of AgNPs in 2% glycerol was 6~10 nm, which was almost same as that in water-based suspension of AgNPs. Zeta potential was ranged from -30 mV to -60 mV, which was in the range of original stock AgNPs. The stability was maintained during the whole experimental period of 48 hours. Furthermore, the stability was not changed in different temperature (10~36$^{\circ}C$) and at different concentrations (10~1,000 ppm). The osmolarity of the AgNPs suspension was $299{\pm}1$ mOsm/kg which was in isotonic range. These data suggest that AgNPs in 2% glycerol solution can be used for the preparations of intravenous injection for toxicokinetic study without undesired disturbance of blood isotonicity.

Synthesis, characterization and dose dependent antimicrobial and anticancerous efficacy of phycogenic (Sargassum muticum) silver nanoparticles against Breast Cancer Cells (MCF 7) cell line

  • Supraja, Nookala;Dhivya, J.;Prasad, T.N.V.K.V.;David, Ernest
    • Advances in nano research
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    • v.6 no.2
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    • pp.183-200
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    • 2018
  • In the present study silver nanoparticles (AgNPs) were successfully synthesized using aqueous extract of Sargassum muticum. The aqueous extract (10%) treated with 1 mM silver nitrate solution resulted in the formation of AgNPs and the surface plasmon resonance (SPR) of the formed AgNPs was recorded at 360 nm using UV-Visible spectrophotometer. The molecules involved in the formation of AgNPs were identified by Fourier transform infrared spectroscopy (FT-IR), surface morphology was studied by using scanning electron microscopy (SEM), SEM micrograph clearly revealed the size of the AgNPs was in the range of 40-65 nm with spherical, hexagonal in shape and poly-dispersed nature, and X-ray diffraction spectroscopy (XRD) was used to determine the crystalline structure. High positive Zeta potential (36.5 mV) of formed AgNPs indicates the stability and XRD pattern revealed the crystal structure of the AgNPs by showing the Bragg's peaks corresponding to (111), (200), (311) and (222) planes of face-centered cubic crystal phase of silver. The synthesized AgNPs exhibited effective anticancerous activity (at doses 25 and $50{\mu}g/ml$ of AgNPs) against Breast cancer cell line (MCF7).

SYNTHESIS OF SILICA-COATED Au WITH Ag, Co, Cu, AND Ir BIMETALLIC RADIOISOTOPE NANOPARTICLE RADIOTRACERS

  • Jung, Jin-Hyuck;Jung, Sung-Hee;Kim, Sang-Ho;Choi, Seong-Ho
    • Nuclear Engineering and Technology
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    • v.44 no.8
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    • pp.971-976
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    • 2012
  • Silica-coated Au with Ag, Co, Cu, and Ir bimetallic radioisotope nanoparticles were synthesized by neutron irradiation, after coating $SiO_2$ onto the bimetallic particles by the sol-gel St$\ddot{o}$ber process. Bimetallic nanoparticles were synthesized by irradiating aqueous bimetallic ions at room temperature. Their shell and core diameters were recorded by TEM to be 100 - 112 nm and 20 - 50 nm, respectively. The bimetallic radioisotope nanoparticles' gamma spectra showed that they each contained two gamma-emitting nuclides. The nanoparticles could be used as radiotracers in petrochemical and refinery processes that involve temperatures that would decompose conventional organic radioactive labels.

Density Functional Theory Study of Separated Adsorption of O2 and CO on Pt@X(X = Pd, Ru, Rh, Au, or Ag) Bimetallic Nanoparticles (Pt 기반 이원계 나노입자의 산소 및 일산화탄소 흡착 특성에 대한 전자밀도함수이론 연구)

  • An, Hyesung;Ha, Hyunwoo;Yoo, Mi;Choi, Hyuck;Kim, Hyun You
    • Korean Journal of Materials Research
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    • v.28 no.6
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    • pp.365-369
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    • 2018
  • We perform density functional theory calculations to study the CO and $O_2$ adsorption chemistry of Pt@X core@shell bimetallic nanoparticles (X = Pd, Rh, Ru, Au, or Ag). To prevent CO-poisoning of Pt nanoparticles, we introduce a Pt@X core-shell nanoparticle model that is composed of exposed surface sites of Pt and facets of X alloying element. We find that Pt@Pd, Pt@Rh, Pt@Ru, and Pt@Ag nanoparticles spatially bind CO and $O_2$, separately, on Pt and X, respectively. Particularly, Pt@Ag nanoparticles show the most well-balanced CO and $O_2$ binding energy values, which are required for facile CO oxidation. On the other hand, the $O_2$ binding energies of Pt@Pd, Pt@Ru, and Pt@Rh nanoparticles are too strong to catalyze further CO oxidation because of the strong oxygen affinity of Pd, Ru, and Rh. The Au shell of Pt@Au nanoparticles preferentially bond CO rather than $O_2$. From a catalysis design perspective, we believe that Pt@Ag is a better-performing Pt-based CO-tolerant CO oxidation catalyst.