• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.66-66
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• 2008

본 연구에서는 ITO/Ag/ITO 다층 박막을 유기발광소자와 플렉시블 광전소자의 전극으로 적용하기 위하여 선형 대항 타겟 스퍼터(Linear facing target sputter) 시스템을 이용하여 성막하였고, ITO/Ag/ITO 다층박막의 전기적, 광학적, 구조적 특성을 분석하였다. 선형 대항 타겟 스퍼터 시스템은 강한 일방항의 자계와 타겟에 걸린 음극에 의해 전자의 회전, 왕복 운동이 가능해 마주보는 두 ITO 타겟 사이에 고밀도의 플라즈마를 구속 시켜 플라즈마 데미지 없이 산화물 박막을 성막시킬 수 있는 장치이다. 대항 타겟 스퍼터 시스템을 이용하여 성막한 ITO 전극을 DC power, working pressure, Ar/O2 ratio 에 따른 특성을 각각 분석하였다. glass 기판위에 최적화된 ITO 전극을 bottom layer로 두고, bottom ITO layer 위에 thermal evaporation 을 이용하여 Ag 박막을 6~20nm의 조건에 따라 두께를 다르게 성막하고, Ag 박막을 성막한 후에 다시 bottom ITO 전극과 같은 조건으로 ITO 전극을 top layer로 성막 하였다. 두 비정질의 ITO 전극 사이에 매우 앓은 Ag 박막을 성막 함으로 해서 glass 기판위에 ITO/Ag/ITO 다층 박막전극은 매우 낮은 저항과 높은 투과도를 나타낸다. ITO/Ag/ITO 박막의 전기적 광학적 특성을 보기 위해 hall measurement와 UV/visible spectrometer 분석을 각각 진행하였다. ITO/Ag/ITO 다층 박막 전극이 매우 얇은 두께임에도 불구하고 $4\Omega$/sq.의 낮은 면저항과 85%의 높은 투과도를 나타내는 이유는 ITO/Ag/ITO 전극 사이에 있는 Ag층의 표면 플라즈몬 공명 (SPR) 현상으로 설명할 수 있다. ITO/Ag/ITO 전극의 Ag의 거동을 분석 하기위해 FESEM분석과 synchrotron x-ray scattering 분석을 하였다. ITO/Ag/ITO 전극의 Ag층이 islands의 모양에서 연속적으로 연결되는 변화과정 중에 SPR현상이 일어남을 알 수 있다. 여기서, 대항 타겟 스퍼터 시스템을 이용하여 성막한 ITO/Ag/ITO 다층박막을 OLED 또는 inverted OLEDs의 top 전극으로의 적용 가능성을 보이고 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.493-493
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• 2014

The manufacturing cost of thin-film photovoltics can potentially be lowered by minimizing the amount of a semiconductor material used to fabricate devices. Thin-film solar cells are typically only a few micrometers thick, whereas crystalline silicon (c-Si) wafer solar cells are $180{\sim}300\mu}m$ thick. As such, thin-film layers do not fully absorb incident light and their energy conversion efficiency is lower compared with that of c-Si wafer solar cells. Therefore, effective light trapping is required to realize commercially viable thin-film cells, particularly for indirect-band-gap semiconductors such as c-Si. An emerging method for light trapping in thin film solar cells is the use of metallic nanostructures that support surface plasmons. Plasmon-enhanced light absorption is shown to increase the cell photocurrent in many types of solar cells, specifically, in c-Si thin-film solar cells and in poly-Si thin film solar cell. By proper engineering of these structures, light can be concentrated and coupled into a thin semiconductor layer to increase light absorption. In many cases, silver (Ag) nanoparticles (NP) are formed either on the front surface or on the rear surface on the cells. In case of poly-Si thin film solar cells, Ag NPs are formed on the rear surface of the cells due to longer wavelengths are not perfectly absorbed in the active layer on the first path. In our cells, shorter wavelengths typically 300~500 nm are also not effectively absorbed. For this reason, a new concept of plasmonic nanostructure which is NPs formed both the front - and the rear - surface is worth testing. In this simulation Al NPs were located onto glass because Al has much lower parasitic absorption than other metal NPs. In case of Ag NP, it features parasitic absorption in the optical frequency range. On the other hand, Al NP, which is non-resonant metal NP, is characterized with a higher density of conduction electrons, resulting in highly negative dielectric permittivity. It makes them more suitable for the forward scattering configuration. In addition to this, Ag NP is located on the rear surface of the cell. Ag NPs showed good performance enhancement when they are located on the rear surface of our cells. In this simulation, Al NPs are located on glass and Ag NP is located on the rear Si surface. The structure for the simulation is shown in figure 1. Figure 2 shows FDTD-simulated absorption graphs of the proposed and reference structures. In the simulation, the front of the cell has Al NPs with 70 nm radius and 12.5% coverage; and the rear of the cell has Ag NPs with 157 nm in radius and 41.5% coverage. Such a structure shows better light absorption in 300~550 nm than that of the reference cell without any NPs and the structure with Ag NP on rear only. Therefore, it can be expected that enhanced light absorption of the structure with Al NP on front at 300~550 nm can contribute to the photocurrent enhancement.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.413-413
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• 2014

In this paper, we present a fabrication method of functionalized gold nanostructures on flexible substrate that can be implemented for plasmonic sensing application. For biomolecular sensing, many researchers exploit unconventional lithography method like nanoimprint lithography (NIP), contact transfer lithography, soft lithography, colloidal transfer printing due to its usability and easy to functionalization. In particular, nanoimprint and contact transfer lithography need to have anti-adhesion layer for distinctive metallic properties on the flexible substrates. However, when metallic thin film was deposited on the anti-adhesion layer coated substrates, we discover much aggravation of the mold by repetitive use. Thus it would be impossible to get a high quality of metal nanostructure on the transferred substrate for developing flexible electronics based transfer printing. Here we demonstrate a method for nano-pillar mold and transfer the controllable nanoparticle array on the flexible substrates without an anti-adhesion layer. Also functionalization of gold was investigated by the different length of thiol applied for effectively localized surface plasmonic resonance sensing. First, a focused ion beam (FIB) and ICP-RIE are used to fabricate the nanoscale pillar array. Then gold metal layer is deposited onto the patterned nanostructure. The metallic 130 nm and 250 nm nanodisk pattern are transferred onto flexible polymer substrate by bi-layer functionalized contact imprinting which can be tunable surface energy interfaces. Different thiol reagents such as Thioglycolic acid (98%), 3-Mercaptopropionic acid (99%), 11-Mercaptoundecanoic acid (95%) and 16-Mercaptohexadecanoic acid (90%) are used. Overcoming the repeatedly usage of the anti-adhesion layer mold which has less uniformity and not washable interface, contact printing method using bi-layer gold array are not only expedient access to fabrication but also have distinctive properties including anti-adhesion layer free, functionalized bottom of the gold nano disk, repeatedly replicate the pattern on the flexible substrate. As a result we demonstrate the feasibility of flexible plasmonic sensing interface and anticipate that the method can be extended to variable application including the portable bio sensor via mass production of stable nanostructure array and other nanophotonic application.

• KSBB Journal
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• 제21권2호
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• pp.133-139
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• 2006

혈액 내 순환시 안정성 향상과 면역원성의 감소를 위해, rhIFN-${\alpha}$-2a은 N-terminus의 ${\alpha}$-아민기에 mPEG aldehyde를 solid-phase PEGylation 시킨다. CM-Sepharose와 같은 양이온 교환수지가 고체 지지체로 사용되었다. Mono-PEGylate는 양이온 교환 수지에서 unmodified 단백질과 분리되어 용출된다. Site-srecific PEGylation과 mono-PEGylate의 분리가 한 단계의 공정으로 얻어진다는 점은 solid-phase PEGylation의 이점을 뒷받침해준다. 위치 특이성은 peptide digest의 질량 분석과 Edman degradation을 이용한 N-terminal sequencing에 의해 확인하였다. Mono-PEGylate는 항바이러스 활성과 면역원성의 감소를 나타내고, 감소 정도는 결합되는 mPEG의 분자량에 비례한다. Trypsin 저항성과 온도 안정성은 mono-PEGylation에 의해 두드러지게 개선되었다. Solid-phase PEGylation을 통해 종래의 액상 반응에서 나타날 수 있는 재현성 낮은 반응, 부 반응물 생성, 부 반응물 제거 공정 등의 단점을 극복할 수 있었다. 그러나 solid-phase PEGylation의 문제점인 액상 반응에 비교하여 많은 양의 PEG를 사용하여야 한다는 점은 개선되어야 한다.

• 산업식품공학
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• 제14권1호
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• pp.49-53
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• 2010

표면 플라즈몬 공명을 이용한 센서는 굴절계 기기의 일종으로서 높은 감도를 가질 뿐만 아니라 비표지 방식이라는 장점을 가지고 있다. 본 연구에서는 재래식 SPR 칩을 이용하여 시판 술 4종의 알코올 함량을 측정하였다. 또한, 재래식 SPR 칩의 감도를 개선하기 위하여 금 박막 위에 금으로 나노형상을 구축하여 나노형상 SPR 칩을 제조하여 모형 술에 대한 감도 개선 효과를 분석하였다. 재래식 SPR 칩을 이용하여 시판 술의 알코올 함량을 측정하기 위한 검량선을 개발하였을 때 시료를 전처리 하지 않고 그대로 측정하였을 때 가장 좋은 검량선을 얻을 수 있었다. 소주, 청주, 이과두주, 탁주 등 시판 술 4종에 대한 1차 회귀식의 검량식에서 결정계수는 각각 0.992, 0.933, 0.918, 그리고 0.984로 나타났다. 한편, 재래식 SPR 칩의 감도를 개선하기 위해 나노형상 SPR 칩을 제조하기 위하여 Langmuir-Blodgett(LB) 방법을 활용하였다. 본 연구에서는 수십 nm 두께의 금 박막을 바닥층으로 하여 그 위에 나노 크기의 실리카 입자를 단분자 층으로 덮어 형틀을 제조하고 다시 그 위에 금을 증착한 후 실리카 입자를 제거하는 방법으로 나노형상을 갖는 SPR 칩을 제조하였다. 나노형상 SPR 칩의 성능을 평가하였을 때 20% 알코올 함량을 가지는 모형 술에 대해서 바닥층의 두께가 50 nm, 나노형상에서 골의 깊이가 20 nm, 나노형상의 배열주기가 300 nm일 때 SPR의 감도가 가장 좋아서 95%의 감도 향상을 얻을 수 있었다. SPR의 감도는 칩과 관련된 인자, 시료의 종류 및 상태에 따라 다르게 나타날 수 있으므로 측정 목적에 알맞은 칩의 설계와 선택이 요구된다.

• 전기전자학회논문지
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• 제22권4호
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• pp.1062-1067
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• 2018

본 연구에서는 화학센서의 개발에 있어서 감지 대상 물질을 정확히 선택적으로 인식하고 그 결과를 물리적 신호로서 발산할 수 있는 분자시스템이 화학센서의 감지부에 도입되고 이러한 기술을 바탕으로 효율적인 감지기술의 개발이 요청되고 있어 미량의 중금속 이온 측정용 화학센서의 연구를 하였다. 본 연구에서는 감지 대상 물질로서 저 농도의 $Ag^+$, $Cu^{2+}$ 이온들을 통하여 이들에 대한 선택적인 감지 결과를 SPR 센서를 응용한 인식 기능성 감지 막 제조를 하여 측정대상 금속이온들에 대한 선택적인 측정을 하여 저 농도에서 매우 정밀 하게 감지 가능한 센서시스템을 구현하였다. 이 결과 DTSQ-dye를 이용한 감지 막 측정 결과의 경우 저 농도 $Ag^+$이온에 따른 공명각의 변화는 $Ag^+$ 이온의 최고농도인 $10^{-4}M$ 까지 공명각의 변화는 $2.17[^{\circ}]$이며, 다른 금속과 비교 시 약 4.3배나 되는 큰 공명각의 변화를 보였고, SQ-dye를 이용한 감지막 측정 결과의 경우 저 농도 $Cu^{2+}$ 이온에 따른 공명각의 변화는 $Cu^{2+}$의 최고농도인 $10^{-4}M$ 까지 공명각의 변화는 $2.3[^{\circ}]$이며 다른 금속과의 비교시 약 4.5배나 되는 큰 공명각의 변화를 보였다.

• Journal of Gastric Cancer
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• 제21권2호
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• pp.191-202
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• 2021

Purpose: A near-infrared (NIR) fluorescence imaging is a promising tool for cancer-specific image guided surgery. Human epidermal receptor 2 (HER2) is one of the candidate markers for gastric cancer. In this study, we aimed to synthesize HER2-specific NIR fluorescence probes and evaluate their applicability in cancer-specific image-guided surgeries using an animal model. Materials and Methods: An NIR dye emitting light at 800 nm (IRDye800CW; Li-COR) was conjugated to trastuzumab and an HER2-specific affibody using a click mechanism. HER2 affinity was assessed using surface plasmon resonance. Gastric cancer cell lines (NCI-N87 and SNU-601) were subcutaneously implanted into female BALB/c nu (6-8 weeks old) mice. After intravenous injection of the probes, biodistribution and fluorescence signal intensity were measured using Lumina II (Perkin Elmer) and a laparoscopic NIR camera (InTheSmart). Results: Trastuzumab-IRDye800CW exhibited high affinity for HER2 (K_D=2.093(3) pM). Fluorescence signals in the liver and spleen were the highest at 24 hours post injection, while the signal in HER2-positive tumor cells increased until 72 hours, as assessed using the Lumina II system. The signal corresponding to the tumor was visually identified and clearly differentiated from the liver after 72 hours using a laparoscopic NIR camera. Affibody-IRDye800CW also exhibited high affinity for HER2 (K_D=4.71 nM); however, the signal was not identified in the tumor, probably owing to rapid renal clearance. Conclusions: Trastuzumab-IRDye800CW may be used as a potential NIR probe that can be injected 2-3 days before surgery to obtain high HER2-specific signal and contrast. Affibody-based NIR probes may require modifications to enhance mobilization to the tumor site.

• Journal of Ginseng Research
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• 제46권1호
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• pp.156-166
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• 2022

Background: Panax ginseng Meyer (P. ginseng), a herb distributed in Korea, China and Japan, exerts benefits on diverse inflammatory conditions. However, the underlying mechanism and active ingredients remains largely unclear. Herein, we aimed to explore the active ingredients of P. ginseng against inflammation and elucidate underlying mechanisms. Methods: Inflammation model was constructed by lipopolysaccharide (LPS) in C57BL/6 mice and RAW264.7 macrophages. Molecular docking, molecular dynamics, surface plasmon resonance imaging (SPRi) and immunofluorescence were utilized to predict active component. Results: P. ginseng significantly inhibited LPS-induced lung injury and the expression of proinflammatory factors, including TNF-α, IL-6 and IL-1β. Additionally, P. ginseng blocked fluorescencelabeled LPS (LPS488) binding to the membranes of RAW264.7 macrophages, the phosphorylation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). Furthermore, molecular docking demonstrated that ginsenoside Ro (GRo) docked into the LPS binding site of toll like receptor 4 (TLR4)/myeloid differentiation factor 2 (MD2) complex. Molecular dynamic simulations showed that the MD2-GRo binding conformation was stable. SPRi demonstrated an excellent interaction between TLR4/ MD2 complex and GRo (K_D value of 1.16 × 10^-9 M). GRo significantly inhibited LPS488 binding to cell membranes. Further studies showed that GRo markedly suppressed LPS-triggered lung injury, the transcription and secretion levels of TNF-α, IL-6 and IL-1β. Moreover, the phosphorylation of NF-κB and MAPKs as well as the p65 subunit nuclear translocation were inhibited by GRo dose-dependently. Conclusion: Our results suggest that GRo exerts anti-inflammation actions by direct inhibition of TLR4 signaling pathway.

• Advances in nano research
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• 제13권5호
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• pp.417-426
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• 2022

Bisphenol A (BPA) is one of the chemicals used in monomer epoxy resins and polycarbonate plastics. The surface-enhanced Raman spectroscopy (SERS) method is precise for identifying biological materials and chemicals at considerably low concentrations. In the present article, the substrates coated with gold nanoparticles have been studied to identify BPA and control the diseases caused by this chemical. Gold nanoparticles were made by a simple chemical method and by applying gold salt and trisodium citrate dihydrate reductant and were coated on glass substrates by a spin-coat approach. Finally, using these SERS substrates as plasmonic sensors and Raman spectroscopy, the Raman signal enhancement of molecular vibrations of BPA was investigated. Then, the molecular vibrations of BPA in some consumer goods were identified by applying SERS substrates as plasmonic sensors and Raman spectroscopy. The fabricated gold nanoparticles are spherical and quasi-spherical nanoparticles that confirm the formation of gold nanoparticles by observing the plasmon resonance peak at 517 nm. Active SERS substrates have been coated with nanoparticles, which improve the Raman signal. The enhancement of the Raman signal is due to the resonance of the surface plasmons of the nanoparticles. Active SERS substrates, gold nanoparticles deposited on a glass substrate, were fabricated for the detection of BPA; a detection limit of 10-9 M and a relative standard deviation (RSD) equal to 4.17% were obtained for ten repeated measurements in the concentration of 10-9 M. Hence, the Raman results indicate that the active SERS substrates, gold nanoparticles for the detection of BPA along with the developed methods, show promising results for SERS-based studies and can lead to the development of microsensors. In Raman spectroscopy, SERS active substrate coated with gold nanoparticles are of interest, which is larger than gold particles due to the resonance of the surface plasmons of gold nanoparticles and the scattering of light from gold particles since the Raman signal amplifies the molecular vibrations of BPA. By decreasing the concentration of BPA deposited on the active SERS substrates, the Raman signal is also weakened due to the reduction of molecular vibrations. By increasing the surface roughness of the active SERS substrates, the Raman signal can be enhanced due to increased light scattering from rough centers, which are the same as the larger particles created throughout the deposition by the spin-coat method, and as a result, they enhance the signal by increasing the scattering of light. Then, the molecular vibrations of BPA were identified in some consumer goods by SERS substrates as plasmonic sensors and Raman spectroscopy.

• Journal of Ginseng Research
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• 제47권6호
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• pp.743-754
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• 2023

Background: Myocardial fibrosis post-myocardial infarction (MI) can induce maladaptive cardiac remodeling as well as heart failure. Although 20(S)-ginsenoside Rg3 (Rg3) has been applied to cardiovascular diseases, its efficacy and specific molecular mechanism in myocardial fibrosis are largely unknown. Herein, we aimed to explore whether TGFBR1 signaling was involved in Rg3's anti-fibrotic effect post-MI. Methods: Left anterior descending (LAD) coronary artery ligation-induced MI mice and TGF-β1-stimulated primary cardiac fibroblasts (CFs) were adopted. Echocardiography, hematoxlin-eosin and Masson staining, Western-blot and immunohistochemistry, CCK8 and Edu were used to study the effects of Rg3 on myocardial fibrosis and TGFBR1 signaling. The combination mechanism of Rg3 and TGFBR1 was explored by surface plasmon resonance imaging (SPRi). Moreover, myocardial Tgfbr1-deficient mice and TGFBR1 adenovirus were adopted to confirm the pharmacological mechanism of Rg3. Results: In vivo experiments, Rg3 ameliorated myocardial fibrosis and hypertrophy and enhanced cardiac function. Rg3-TGFBR1 had the 1.78×10^-7 M equilibrium dissociation constant based on SPRi analysis, and Rg3 inhibited the activation of TGFBR1/Smads signaling dose-dependently. Cardiac-specific Tgfbr1 knockdown abolished Rg3's protection against myocardial fibrosis post-MI. In addition, Rg3 downregulated the TGF-β1-mediated CFs growth together with collagen production in vitro through TGFBR1 signaling. Moreover, TGFBR1 adenovirus partially blocked the inhibitory effect of Rg3. Conclusion: Rg3 improves myocardial fibrosis and cardiac function through suppressing CFs proliferation along with collagen deposition by inactivation of TGFBR1 pathway.