• 한국전기전자재료학회논문지
• /
• 제32권6호
• /
• pp.458-461
• /
• 2019

The facile synthesis of shape-controlled Pd nanoparticles (PdNPs) with ascorbic acid as a reducing agent and cetyltrimethylammonium bromide (CTAB) as a capping agent is presented in this study. The synthesized PdNPs were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman Spectroscopy. The prepared PdNPs show efficient surface-enhanced Raman scattering (SERS) properties. SERS studies on the adsorption characteristics of 1,4-phenylene diisocyanide (1,4-PDI) on colloidal PdNPs have revealed that the relative peak intensity of the $(NC)_{free}$ and $(NC)_{bound}$ modes distinctly depends on the 1,4-PDI concentration as well as the shape of the PdNPs. Furthermore, we found that the PdNPs are also efficient photoelectron emitters such that the SERS spectrum of 4-nitrobenzenethiol (4-NBT) on PdNPs is readily converted to that of 4-aminobenzenethiol (4-ABT) under 632.8 nm radiation.

• Advances in nano research
• /
• 제5권4호
• /
• pp.373-392
• /
• 2017

Silver nanoparticles (AgNPs) were successfully synthesized through a simple green route using the Nelumbo nucifera leaf, stem and flower extracts. These nanoparticles showed characteristic UV-Vis absorption peaks between 410-450 nm which arises due to the plasmon resonance of silver nanoparticles. The Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of amides and which acted as the stabilizing agent. X-ray diffraction spectrum of the nanoparticles confirmed the Face centered cubic (FCC) structure of the formed AgNPs. Dynamic light scattering technique was used to measure hydrodynamic diameter (68.6 nm to 88.1 nm) and zeta potential (-55.4 mV, -57.9 mV and 98.9 mV) of prepared AgNPs. The scanning electron micrographs of dislodged nanoparticles in aqueous solution showed the production of reasonably monodispersed silver nanoparticles (1-100 nm). The antimicrobial activity of prepared AgNPs was evaluated against fungi, Gram-positive and Gram-negative bacteria using disc diffusion method. Anti-corrosion studies were carried out using coupon method (mild steel and iron) and dye degradation studies were carried out by assessing photo-catalytic activity of Nelumbo nucifera extracts mediated AgNPs.

• 생약학회지
• /
• 제41권4호
• /
• pp.323-327
• /
• 2010

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of dictamine, obacunone and fraxinellone was established for the quality control of traditional herb Dictamnus dasycarpus cortex. Separation and quantification were successfully achieved with a Shiseido C18 column ($5\;{\mu}m$, 4.6 mm I.D. ${\times}$ 250 mm) by gradient elution of a mixture of methanol and water at a flow rate of 1.0 ml/min. The diode-array UV/Vis detector (DAD) was used for the detection and the wavelength for quantification was set at 236 nm. The presence of dictamine, obacunone and fraxinellone in this extract was ascertained by retention time, spiking with each authentic standard and UV spectrum. All three compounds showed good linearity ($r^2$ > 0.999) in relatively wide concentration ranges. The R.S.D. recovery of each compound was 101.0~103.7% with R.S.D. values less than 1.0%. This method was successfully applied to the determination of contents of dictamine, obacunone and fraxitnellone in three commercial products of D. dasycarpus cortex. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial products.

• Natural Product Sciences
• /
• 제14권3호
• /
• pp.147-151
• /
• 2008

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of marker constituents, baicalin and glycyrrhizin was established for the quality control of traditional herbal medicinal preparation, Eul-Ja-Tang (EJT). Separation and quantification were successfully achieved with a Waters XTerra RP18 column ($5{\mu}m$, 4.6 mm I.D. ${\times}$ 150 mm) by gradient elution of a mixture of acetonitrile and water containing 0.03% phosphoric acid (pH 2.03) at a flow rate of 1.0 mL/min. The diode-array UV/VIS detector (DAD) was used for the detection and the wavelength for quantification was set at 250 nm. The presence of baicalin and glycyrrhizin in this decoction was ascertained by retention time, spiking with each authentic standard and UV spectrum. Both baicalin and glycyrrhizin showed good linearity ($r^2$ > 0.999) in a relatively wide concentration ranges. The R.S.D. for intra-day and inter-day precision was less than 5% and the limits of detection (LOD) were about 30 ng. The mean recovery of each compound was 99.5 - 101.2% with R.S.D. values less than 4.0%. This method was successfully applied to the determination of contents of baicalin and glycyrrhizin in three commercial products of EJT, which resulted in the difference in the contents of these compounds. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial EJT products.

• Journal of Pharmaceutical Investigation
• /
• 제39권1호
• /
• pp.23-27
• /
• 2009

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of marker constituents, paeoniflorin and glycyrrhizin was established for the quality control of traditional herbal medicinal preparation, Sayuk-san (SYS). Separation and quantification were successfully achieved with a Waters XTerra RP18 column ($5{\mu}m$, $4.6mm\;I.D.{\times}150mm$) by gradient elution of a mixture of acetonitrile and water containing 0.03% phosphoric acid (pH 2.03) at a flow rate of 1.0 mL/min. The diode-array UV/vis detector (DAD) was used for the detection and the wavelength for quantification was set at 230 nm. The presence of paeoniflorin and glycyrrhizin in this decoction was ascertained by retention time, spiking with each authentic standard and UV spectrum. All two compounds showed good linearity ($r^2$>0.996) in a relatively wide concentration ranges. The R.S.D. for intra-day and inter-day precision was less than 7.3% and the limits of detection (LOD) were less than 55.7 ng. The mean recovery of each compound was $102.3{\sim}111.1%$ with R.S.D. values less than 4.6%. This method was successfully applied to the determination of contents of paeoniflorin and glycyrrhizin in three commercial products of SYS. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial SYS products.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.222.1-222.1
• /
• 2015

Recently, graphene quantum dots (GQDs) have attracted great attention due to various properties including cost-effectiveness of synthesis, low toxicity, and high photostability. Nevertheless, the origins of photoluminescence (PL) from GQDs are unclear because of extrinsic states of the impurities, disorder structures, and oxygen-functional groups. Therefore, to utilize GQDs in various applications, their optical properties generated from the extrinsic states should be understood. In this work, we have focused on the effect of oxygen-functional groups in PL of the GQDs. The GQDs with nanoscale and single layer are synthesized by employing graphite nanoparticles (GNPs) with 4 nm. The series of GQDs with different amount of oxygen-functional groups were prepared by the chain of chemical oxidation and reduction process. The fabrication of a series of graphene oxide QDs (GOQDs) with different amounts of oxygen-contents is first reported by a direct oxidation route of GNPs. In addition, for preparing a series of reduced GOQDs (rGOQDs), we employed the conventional chemical reduction to GOQDs solution and controlled the amount of reduction agents. The GOQDs and rGOQDs showed irreversible PL properties even though both routes have similar amount of oxyen-functional groups. In the case of a series of GOQDs, the PL spectrum was clearly redshifted into blue and green-yellowish color. On the other hand, the PL spectrum of rGOQDs did not change significantly. By various optical measurement such as the PL excitation, UV-vis absorbance, and time-resolved PL, we could verify that their PL mechanisms of GOQDs and rGOQDs are closely associated with different atomic structures formed by chemical oxidation and reduction. Our study provides an important insights for understanding the optical properties of GQDs affected by oxygen-functional groups. [1]

• 한국염색가공학회지
• /
• 제19권4호
• /
• pp.32-37
• /
• 2007

In this study, we have obtained the protein patterns using the membrane patterning of soft-lithography technique. The rapid detection of protein including bovine serum albumin (BSA) was resulted from the interaction with 1,3-bisdicyanovinylindane. For the proof of the interaction between BSA and dye, the UV-vis absorption spectra of BSA and dye were observed at 278 nm and 580 nm, respectively. As expected, the absorption spectrum of the interaction between BSA and dye was observed at 584nm. The absorption spectrum of the interaction was red-shifted. In addition, the optical images of the selectively reacted protein patterns showed the distinctive change of patterned color at different pH conditions. Because the dye has negative charges, the charge of BSA at different pH conditions could influence the interaction behavior between dye and BSA. Therefore, in the case of pH 7, the selectively patterned protein substrates obtained deep blue color pattern caused by electrostatic interaction between negative charges of the dye and positive charges of the BSA. However, in the case of pH 10, selectively patterned protein substrates obtained light blue color pattern because the electrostatic interaction was relatively lower than pH 7 due to the change of overall charge distribution of BSA.

• 한국광물학회지
• /
• 제21권2호
• /
• pp.117-127
• /
• 2008

카올리나이트 KGa-2 (표준 점토)의 인산염 흡착-탈착 특성을 규명하기 위하여 벳치(batch) 흡착 실험을 실시하였으며, 흡착 상태를 알아보기 위하여 ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) 분광분석을 실시하였다. 인의 함량은 UV-VIS-IR 분광분석 기를 사용하여 측정하였으며, 이 때 파장은 820 nm를 이용하였다. pH 4에서 pH 9 범위 내에서 카올리나이트 KGa-2의 인산염 흡착량은 pH가 증가하면 대체적으로 증가하는 경향을 나타내지만, 인산염 농도에 따라 매우 다른 형태를 보여준다. 카올리나이트 KGa-2의 인산염 흡착 특성은 랑미어 흡착등온선, 템킨 흡착등온선, 프로인드리히 흡착등온선 순으로 잘 부합하며, 랑미어 최대 흡착능은 $204.1{\sim}256.5\;mg/kg$, 평균간은 232.5 mg/kg으로서, 카올리나이트 KGa-1b에 비하여 높은 인산염 흡착능을 가진다. 카올리나이트에 흡착된 대부분의 인산염이 탈착되기보다, 광물 내에 고착되는 경향을 나타내지만 이에 대해서는 후속적인 실험이 필요한 것으로 판단된다. ATR${\sim}$FTIR 스펙트럼에서 카올리나이트에 의한 흡수피크의 위치가 인 피크와 거의 중첩되고, 카올리나이트에 의한 흡수 피크의 강도가 인 피크에 비하여 월등히 크기 때문에 카올리나이트에 흡착된 인에 의한 피크를 카올리나이트 자체에 의한 피크로부터 분리하는 것이 거의 불가능하였다.

• 한국미생물·생명공학회지
• /
• 제46권2호
• /
• pp.120-126
• /
• 2018

환경친화적으로 항균성이 부여된 상처치료용 BC 드레싱을 개발하기 위한 기초연구로서, 은 이온에 대해 내성이 있으면서 은 나노입자를 생합성할 수 있는 초산균을 분리 및 동정하였다. 나아가 실험균주에 의한 BC 생산 조건을 조사하였다. 부패된 포도껍질로부터 분리된 G7 균주는 0.1 mM $AgNO_3$ 존재 하에서 생육할 수 있었으며, 16S rRNA 유전자의 염기서열 분석에 의거하여 Acetobacter intermdius로 동정되었다. 탄소원으로 2% glucose, 질소원으로 2% yeast extract, 보조탄소원으로 0.115% acetic acid가 함유된 배지에서 BC 생산량이 최대였다. 최적배지에서 생성된 BC의 구조적 특성을 FT-IR 및 XRD를 사용하여 조사한 결과, 생성된 BC는 전형적인 천연 cellulose와 동일한 cellulose I인 것으로 확인되었다. G7 균주를 0.1 mM $AgNO_3$ 가 함유된 최적 배지에서 배양한 결과, 배양액의 색깔이 적갈색으로 변하였으며, 이것은 은 나노입자가 생성되었음을 의미한다. 은 나노입자의 합성유무를 UV-Vis 스펙트럼 분석에 의하여 확인한 바, 425 nm에서 은 나노입자의 고유한 흡수스펙트럼이 관찰되었다. 또한, 생성된 BC를 주사전자현미경으로 관찰한 결과, 표면과 기공에 은 나노입자가 생성되어 있음을 재확인하였다.

• 대한화학회지
• /
• 제53권6호
• /
• pp.677-682
• /
• 2009

본 논문에서는 ZnS:Mn/ZnS 코어-쉘 양자점을 유기금속전구체의 열분해 방법으로 합성하였다. 쉘의 형성온도를 135$^{\circ}C$로 고정한 반면 코어 나노입자의 합성 온도 조건을 다양화 하여 각 조건하에서 형성된 양자점들의 특성을 조사하였다. 실험을 통해 얻은 양자점들은 UV-Vis, 액체 photoluminescence (PL) spectroscopy 방법으로 광 특성을 조사하였으며, 또한 XRD, HR-TEM, 및 EDXS 분석으로 입자크기와 조성 등을 측정하였다. 실험 결과 가장 좋은 광 특성을 보인 나노입자의 합성조건은 코어와 쉘 모두 135$^{\circ}C$인 것으로 밝혀 졌으며, 이 조건에서 얻은 양자점은 583 nm 의 PL 발광 피이크와 42.15%의 높은 양자효율을 나타내었다. HR-TEM 으로 측정한 ZnS:Mn/ZnS 양자점의 평균 입자크기는 지름이 약 4.0 - 5.4 nm 정도였으며, 특히 150$^{\circ}C$의 온도 조건에서는 타원형의 입자가 형성되는 것이 관찰되었다.