• Title/Summary/Keyword: Au nanoparticles

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Development of Highly Stable Organic Nonvolatile Memory

  • Baeg, Kang-Jun;Kim, Dong-Yu;You, In-Kyu;Noh, Yong-Young
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.904-906
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    • 2009
  • Organic field-effect transistor (OFET) memory is an emerging device for its potential to realize light-weight, low cost flexible charge storage media. Here we report on a solution-processed poly[9,9-dioctylfluorenyl-2,7-diyl]-co-(bithiophene)] (F8T2) nano floating-gate memory (NFGM) with top-gate/bottom-contact device configuration. A reversible shift in the threshold voltage ($V_{Th}$) and the reliable memory characteristics were achieved by incorporation of thin Au nanoparticles (NPs) as charge storage sites for negative electrons at the interface between polystyrene and cross-linked poly(4-vinylphenol).

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An electrochemical hydrogen peroxide sensor for applications in nuclear industry

  • Park, Junghwan;Kim, Jong Woo;Kim, Hyunjin;Yoon, Wonhyuck
    • Nuclear Engineering and Technology
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    • v.53 no.1
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    • pp.142-147
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    • 2021
  • Hydrogen peroxide is a radiolysis product of water formed under gamma-irradiation; therefore, its reliable detection is crucial in the nuclear industry for spent fuel management and coolant chemistry. This study proposes an electrochemical sensor for hydrogen peroxide detection. Cysteamine (CYST), gold nanoparticles (GNPs), and horseradish peroxidase (HRP) were used in the modification of a gold electrode for fabricating Au/CYST/GNP/HRP sensor. Each modification step of the electrode was investigated through electrochemical and physical methods. The sensor exhibited strong sensitivity and stability for the detection and measurement of hydrogen peroxide with a linear range of 1-9 mM. In addition, the Michaelis-Menten kinetic equation was applied to predict the reaction curve, and a quantitative method to define the dynamic range is suggested. The sensor is highly sensitive to H2O2 and can be applied as an electrochemical H2O2-sensor in the nuclear industry.

Selective Enhancement of the Sheet Resistance of Graphene Using Dielectrophoresis (유전영동 현상을 이용한 그래핀 면저항의 선택적 향상 연구)

  • Oh, Sooyeoun;Kim, Jihyun
    • Korean Chemical Engineering Research
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    • v.55 no.2
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    • pp.253-257
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    • 2017
  • Graphene is a monolayer carbon material which consists of $sp^2$ bonding between carbon atoms. Its excellent intrinsic properties allow graphene to be used in various research fields. Many researchers believe that graphene is suitable for electronic device materials due to its high electrical conductivity and carrier mobility. Through chemical doping, n- or p-type graphene can be obtained, and consequently graphene-based devices which have more comparable structure to common semiconductor-based devices can be fabricated. In our research, we introduced the dielectrophoresis process to the chemical doping step in order to improve the effect of chemical doping of graphene selectively. Under 10 kHz and $5V_{pp}$ (peak-to-peak voltage), doping was conducted and the Au nanoparticles were effectively formed, as well as aligned along the edges of graphene. Effects of the selective chemical doping on graphene were investigated through Raman spectroscopy and the change of its electrical properties were explored. We proposed the method to enhance the doping effect in local region of a graphene layer.

Characteristics of photo-thermal reduced Cu film using photographic flash light

  • Kim, Minha;Kim, Donguk;Hwang, Soohyun;Lee, Jaehyeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.293.1-293.1
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    • 2016
  • Various materials including conductive, dielectric, and semi-conductive materials, constitute suitable candidates for printed electronics. Metal nanoparticles (e.g. Ag, Cu, Ni, Au) are typically used in conductive ink. However, easily oxidized metals, such as Cu, must be processed at low temperatures and as such, photonic sintering has gained significant attention as a new low-temperature processing method. This method is based on the principle of selective heating of a strongly absorbent film, without light-source-induced damage to the transparent substrate. However, Cu nanoparticles used in inks are susceptible to the growth of a native copper-oxide layer on their surface. Copper-oxide-nanoparticle ink subjected to a reduction mechanism has therefore been introduced in an attempt to achieve long-term stability and reliability. In this work, a flash-light sintering process was used for the reduction of an inkjet-printed Cu(II)O thin film to a Cu film. Using a photographic lighting instrument, the intensity of the light (or intense pulse light) was controlled by the charged power (Ws). The resulting changes in the structure, as well as the optical and electrical properties of the light-irradiated Cu(II)O films, were investigated. A Cu thin film was obtained from Cu(II)O via photo-thermal reduction at 2500 Ws. More importantly, at one shot of 3000 Ws, a low sheet resistance value ($0.2527{\Omega}/sq.$) and a high resistivity (${\sim}5.05-6.32{\times}10^{-8}{\Omega}m$), which was ~3.0-3.8 times that of bulk Cu was achieved for the ~200-250-nm-thick film.

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Highly sensitive and selective detection of cyanide in aqueous solutions using a surface acoustic wave chemical sensor (표면음향파 화학센서를 이용한 수용액 중 시안화이온의 선택적인 고감도 검출)

  • Lee, Soo Suk
    • The Journal of the Acoustical Society of Korea
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    • v.35 no.6
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    • pp.473-479
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    • 2016
  • We report a highly selective and sensitive 200 MHz Surface Acoustic Wave (SAW) sensor that can detect cyanide ion in aqueous solution using surface immobilized thioester molecules in combination with gold nanoparticles (AuNPs). To construct the sensor device, a monolayer of thioester compound was immobilized on the SAW sensor surface. At the sensor surface, hydrolysis of thioester group by nucleophilic addition of cyanide occurred and the resulting free thiol unit bound to AuNP to form thiol-AuNP conjugate. For the signal enhancement, gold staining signal amplification process was introduced subsequently with gold (III) chloride trihydrate and reducing agent, hydroxylamine hydrochloride. The SAW sensor showed a detection ability of $17.7{\mu}M$ for cyanide in aqueous solution and demonstrated a saturation behavior between the frequency shift and the concentration of cyanide ion. On the other hand, our SAW sensor had no activities for other anions such as fluoride ion, acetate ion and sulfate ion, moreover, no significant interference observed by other anions. Finally, all the experiments were carried out in-house developed sensor and fluidics modules to obtain highly reproducible results.

Development of Voltammetric Nanobio-incorporated Analytical Method for Protein Biomarker Specific to Early Diagnosis of Lung Cancer (폐암 조기 진단을 위한 단백질 바이오마커 측정용 전압-전류법 기반의 나노바이오 분석법 개발)

  • Li, Jingjing;Si, Yunpei;Nde, Dieudonne Tanue;Lee, Hye Jin
    • Applied Chemistry for Engineering
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    • v.32 no.4
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    • pp.461-466
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    • 2021
  • In this article, a portable and cost-effective voltammetric biosensor with nanoparticles was developed for the measurements of heterogeneous nuclear ribonucleoprotein A1 protein (hnRNP A1) biomarker which can potentially be used for lung cancer diagnosis. Gold nanoparticles were first electrodeposited onto screen printed carbon electrode (SPCE) followed by immobilizing a single stranded DNA aptamer specific to hnRNP A1 onto the electrode surface. Ethanolamine was also used when immobilizing DNA aptamer on the surface to prevent signals from non-specific adsorption events. Sequential injection of hnRNP A1 biomarker and anti-hnRNP A1 conjugated with alkaline phosphatase (ALP) onto the aptamer chip surface allows to form the sandwich complex of DNA aptamer/hnRNP A1/ALP-anti-hnRNP A1 on the electrode surface which further reacted with 4-aminophenyl phosphate (APP). The electrocatalytic reaction of the enzyme, ALP, and the substrate, APP, resulting in the oxidative current response changes at -0.05 and -0.17 V (vs. Ag/AgCl) against the hnRNP A1 concentration was measured using cyclic and differential pulse voltammetry, respectively. The Au nanoparticles-integrated voltammetric biosensor was applied to analyze human normal serum solutions possibly suggesting potential applicability for lung cancer diagnosis.

Synthesis and characterization of noble metal coupled N-TiO2 nanoparticles

  • Lee, Kyusang;Moon, Jiyeon;Kim, Seonmin
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.374.2-374.2
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    • 2016
  • Volatile organic compounds (VOCs) in the atmosphere are harmful materials which influence indoor air environment and human health. Titanium dioxide ($TiO_2$) is photocatalyst extensively used in degradation of organic compound. To improve the photocatalytic activity in the visible light region, doping with non-metals element or loading noble metals on the surface of $TiO_2$ is generally proposed. In this study, N- doped $TiO_2$ having photocatalytic activity in visible light region was attached noble metal such as Pt, Ag, Pd, Au by coupling method. Catalytic activities of Noble metal coupled $N-TiO_2$ powders were evaluated by the improvement of their photocatalytic activities and the degradation of VOC gas. A UV-Vis spectrophotometer was used to measure the diffuse reflectance spectra of coupled $N-TiO_2$ sample. The photocatlytic activities of as prepared samples were characterized by the decoloration of aqueous MB solution under Xenon light source (UV and visible light). To measure of decomposition VOCs, ethylbenzene was selected for target VOC material and the concentration was monitored under UVLED irradiation in a closed chamber system. Adjusting the initial concentration of 10~12 ppm, to evaluate the removal characteristics by using the coupled $N-TiO_2$.

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Pre-validation of Colony Forming Efficiency Assay for Assessing the Cytotoxicity of Nanomaterials (나노물질의 세포독성 평가법으로 Colony Forming Efficiency Assay에 대한 검증연구)

  • Jo, Eunhye;Lee, Jaewoo;Park, Sun-Young;Kim, Pilje;Choi, Kyunghee;Eom, Igchun
    • Journal of Environmental Health Sciences
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    • v.41 no.1
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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.