• Title, Summary, Keyword: Ag nanoparticles

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Biosynthesis of Silver Nanoparticles Using Microorganism (미생물을 이용한 은 나노입자 생합성)

  • Yoo, Ji-Yeon;Jang, Eun-Young;Hong, Chang-Oh;Kim, Keun-Ki;Park, Hyean-Cheal;Lee, Sang-Mong;Kim, Young-Gyun;Son, Hong-Joo
    • Journal of Life Science
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    • v.28 no.11
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    • pp.1354-1360
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    • 2018
  • The aim of this study was to develop a simple, environmentally friendly synthesis of silver nanoparticles (SNPs) without the use of chemical reducing agents by exploiting the extracellular synthesis of SNPs in a culture supernatant of Bacillus thuringiensis CH3. Addition of 5 mM $AgNO_3$ to the culture supernatant at a ratio of 1:1 caused a change in the maximum absorbance at 418 nm corresponding to the surface plasmon resonance of the SNPs. Synthesis of SNPs occurred within 8 hr and reached a maximum at 40-48 hr. The structural characteristics of the synthesized SNPs were investigated by various instrumental analysis. FESEM observations showed the formation of well-dispersed spherical SNPs, and the presence of silver was confirmed by EDS analysis. The X-ray diffraction spectrum indicated that the SNPs had a face-centered cubic crystal lattice. The average SNP size, calculated using DLS, was about 51.3 nm and ranged from 19 to 110 nm. The synthesized SNPs exhibited a broad spectrum of antimicrobial activity against a variety of pathogenic Gram-positive and Gram-negative bacteria and yeasts. The highest antimicrobial activity was observed against C. albicans, a human pathogenic yeast. The FESEM observations determined that the antimicrobial activity of the SNPs was due to destruction of the cell surface, cytoplasmic leakage, and finally cell lysis. This study suggests that B. thuringiensis CH3 is a potential candidate for efficient synthesis of SNPs, and that these SNPs have potential uses in a variety of pharmaceutical applications.

A Review of SERS for Biomaterials Analysis Using Metal Nanoparticles (바이오 물질 분석을 위한 금속 나노입자를 이용한 SERS 분석 연구동향)

  • Jang, Eue-Soon
    • Ceramist
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    • v.22 no.3
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    • pp.281-300
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    • 2019
  • Surface enhanced Raman scattering (SERS) was first discovered in 1974 by an unexpected Raman signal increase from Pyridine adsorbed on rough Ag electrode surfaces by the M. Fleishmann group. M. Moskovits group suggested that this phenomenon could be caused by surface plasmon resonance (SPR), which is a collective oscillation of free electrons at the surface of metal nanostructures by an external light source. After about 40 years, the SERS study has attracted great attention as a biomolecule analysis technology, and more than 2500 new papers and 500 review papers related to SERS topic have been published each year in recently. The advantages of biomaterials analysis using SERS are as follows; ① Molecular level analysis is possible based on unique fingerprint information of biomolecule, ② There is no photo-bleaching effect of the Raman reporters, allowing long-term monitoring of biomaterials compared to fluorescence microscopy, ③ SERS peak bandwidth is approximately 10 to 100 times narrower than fluorescence emission from organic phosphor or quantum dot, resulting in higher analysis accuracy, ④ Single excitation wavelength allows analysis of various biomaterials, ⑤ By utilizing near-infrared (NIR) SERS-activated nanostructures and NIR excitation lasers, auto-fluorescence noise in the visible wavelength range can be avoided from in vivo experiment and light damage in living cells can be minimized compared to visible lasers, ⑥ The weak Raman signal of the water molecule makes it easy to analyze biomaterials in aqueous solutions. For this reason, SERS is attracting attention as a next-generation non-invasive medical diagnostic device as well as substance analysis. In this review, the principles of SERS and various biomaterial analysis principles using SERS analysis will be introduced through recent research papers.

XAS Studies of Ion Irradaited MgO Thin Films

  • Suk, Jae-Kwon;Gautam, Sanjeev;Song, Jin-Ho;Lee, Jae-Yong;Kim, Jae-Yeoul;Kim, Joon-Kon;Song, Jong-Han;Chae, Keun-Hwa
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.312-312
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    • 2012
  • Magnesium oxide has become focus for research activities due to its use in magnetic tunnel junctions and for understanding of do ferromagnetism. Theoretical investigations on such type of system indicate that the presence of defects greater than a threshold value is responsible for the magnetic behaviour. It has also been shown experimentally that by decreasing the film thickness and size of nanoparticles, enhancement/increase in magnetization can be achieved. Apart from the change in dimension, swift heavy ions (SHI) are well known for creating defects and modifying the properties of the materials. In the present work, we have studied the irradiation induced effects in magnesium oxide thin film deposited on quartz substrate via X-ray absorption spectroscopy (XAS). Magnesium oxide thin films of thickness 50nm were deposited on quartz substrate by using e-beam evaporation method. These films were irradiated by 200 MeV Ag15+ ion beam at fluence of $1{\times}10^{11}$, $5{\times}10^{11}$, $1{\times}10^{12}$, $3{\times}10^{12}$ and $5{\times}10^{12}ions/cm^2$ at Nuclear Science Centre, IUAC, New Delhi (India). The grain size was observed (as studied by AFM) to be decreased from 37 nm (pristine film) to 23 nm ($1{\times}10^{12}ions/cm^2$) and thereafter it increases upto a fluence of $5{\times}10^{12}ions/cm^2$. The electronic structure of the system has been investigated by X-ray absorption spectroscopy (XAS) measurements performed at the high energy spherical grating monochromator 20A1 XAS (HSGM) beamline in the National Synchrotron Radiation Research Center (NSRRC), Taiwan. Oxides of light elements like MgO/ZnO possess many unique physical properties with potentials for novel application in various fields. These irradiated thin films are also studied with different polarization (left and right circularly polarized) of incident x-ray beam at 05B3 EPU- Soft x-ray scattering beamline of NSRRC. The detailed analysis of observed results in the wake of existing theories is discussed.

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Fabrication Process of Natural Silk Including Ag Nano-particle (은나노 입자가 함유된 천연실크 제조 방법)

  • Jung, I-Yeon;Kang, Pil-Don;Kim, Kee-Young;Ryu, Kang-Sun;Sohn, Bong-Hee;Kim, Yong-Soon;Kim, Mi-Ja;Lee, Kwang-Gill;Chai, Chang-Keun;Koh, Seok-Keun
    • Journal of Sericultural and Entomological Science
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    • v.49 no.1
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    • pp.24-27
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    • 2007
  • Silkworm fed on the mulberry leaf mixed with silver nanoparticle to produce silver-nanoparticle embedded cocoon. Comparative analysis of silver content of cocoon shell, percentage of pupation and percentage of cocoon-shell weight showed that the optimum concentration and the feeding period of mulberry leaf mixed with silver nanoparticle were 500 ppm and the period from 3 day 5 instar to mounting of silkworm. The silver content of cocoon was observed variously by silkworm breedings. C212 variety makes pale yellow cocoon with the highest silver content(69%). Using the scanning electron microscope, we showed that the size of silver nanoparticles in silk was observed from 26.98 to 99.81nm. Silver-nanoparticle embedded silk is expected to use as high valuable application owing to the different functional properties including antibiotic characteristics and mechanical and electronic properties. The applicable fields expected is antistatic and/or electronic products with biological degradable natural materials.