• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.81-88
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• 2007

The sprC gene encodes Streptomyces griseus protease C (SGPC), a bacterial chymotrypsin-like serine protease. Because the published data on sprC was not complete, we cloned and analyzed a new DNA fragment spanning downstream to upstream of the sprC gene from S. griseus IFO13350. The cloned 2.3-kb DNA fragment was placed on a high-copy number plasmid and introduced into Streptomyces lividans TK24. Chymotrypsin activity of the transformant was 8.5 times higher than that of the control after 3 days of cultivation and stably maintained until 9 days of cultivation, which dearly indicated that the cloned 2.3-kb fragment contained the entire sprC gene with its own promoter. When the same construct was introduced in the S. griseus IFO13350 (wild strain) and its two mutant strains in the A-factor regulatory cascade, ${\Delta}adpA$ and HO1, the chymotrypsin activity increased fivefold only in the ${\Delta}adpA$ strain. Transcriptional analysis based on RT-PCR revealed that the sprC gene is normally transcribed in both strains; however, earlier transcription was observed in the wild strain compared with the ${\Delta}adpA$ strain. A gel mobility shift assay showed that the AdpA protein did not bind to the promoter region of sprC. All these data clearly indicate that the expression of sprC is not dependent on the AdpA protein, but is distinctly regulated from other chymotrypsin genes composing an AdpA regulon. Earlier morphological differentiation was observed in S. lividans TK24, and S. griseus IFO13350 and HO1, transformed with the expression vector. The transformant of S. griseus ${\Delta}adpA$ formed markedly larger colonies. Antisense repression of sprC resulted in severe decrease of chymotrypsin activity, down to one-third of the control, and delayed morphological differentiation. All these data suggest that SGPC is related to normal morphogenesis in S. griseus.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권10호
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• pp.492-498
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• 2006

A novel surface plasmon resonance(SPR) multisensing method, which does not require imaging apparatus such as CCD, has been proposed and implemented experimentally. The proposed method is based on the multichannel SPR and the separation of signals by use of additional layers whose thickness is controlled. SPR signals are influenced by the thickness of sensing layer as well as the optical condition of sensing surface. As the SPR signals from different ligands are usually positioned closely, the reflected light from sensing surface does not provide us with the clear differences of resonance signal depending on the kinds of ligands. It was found from our experiments that SPR signals from each ligand that is located on the additional layer with different thickness can be separated clearly enough to identify various signals from different ligands. Proposed method with theoretical design and simulation has been verified experimentally by using $SiO_2$ thin film layer as additional layer.

• Tuberculosis and Respiratory Diseases
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• 제60권4호
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• pp.412-418
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• 2006

연구배경 : 클라미디아 감염의 진단은 혈청검사로 이루어진다. 현재 표준 방법은 MIF(microimmunofluorescence)이나 이 방법은 주관적이고 시간이 많이 걸리는 단점이 있다. 최근을 SPR(surface plasmon resonance) 센서를 이용한 단백질 칩이 감염의 새로운 진단 방법으로 제시되고 있다. 클라미디아 감염의 진단을 위한 단백질 칩 개발을 위하여 금 칩 표면에 세균을 고정하고 클라미디아 균에 대한 항체와 표면 위 세균과의 반응을 SPR 센서를 이용하여 측정하고자 하였다. 방법 : 표면 항원으로 배양한 Chlamydophila pneumoniae LKK1의 EB를 정제하였다. 양전하를 띤 PDDA (polydiallyldimethylammonium chloride)를 이용하여 전하를 이용한 단백질 칩을 제작하였다. 클라미디아 균을 고정시킨 후에 atomic force microscopy를 이용하여 표면을 관찰하였다. 클라미디아 균에 대한 항체를 투여하고 나서 자체 제작한 SPR 센서를 이용하여 항원 항체 반응을 SPR 파장 변화로 측정하였다. 결과 : 양전하를 띤 PDDA 표면위에서 클라미디아 균이 고정되었음을 확인 하였다. 그리고, 항체를 투여한 후에 SPR 파장의 증가를 확인하였다. 파장 변화는 항원의 농도와 관련이 있었다. 결론 : 전하를 이용하여 클라미디아 폐렴균의 EB를 단백질 칩에 고정하였고, 단백질 칩 위에서의 항원 항체 반응을 확인하였다. 비정형 폐렴의 진단에 SPR 센서가 기여할 수 있을 것으로 사료되나, 실제 임상 시료에의 적용을 위해서는 좀더 연구가 필요할 것으로 사료된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.401-401
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• 2014

In this study, graphene, the most attractive material today, has been applied to the wavelength-modulated surface plasmon resonance (SPR) sensor. The optical fiber sensor technology is the most fascinating topic because of its several benefits. In addition to this, the SPR phenomenon enables the detection of biomaterials to be label-free, highly sensitive, and accurate. Therefore, the optical fiber SPR sensor has powerful advantages to detect biomaterials. Meanwhile, Graphene shows superior mechanical, electrical, and optical characteristics, so that it has tremendous potential to be applied to any applications. Especially, grapheme has tighter confinement plasmon and relatively long propagation distances, so that it can enhance the light-matter interactions (F. H. L. Koppens, et al., Nano Lett., 2011). Accordingly, we coated graphene on the optical fiber probe which we fabricated to compose the wavelength-modulated SPR sensor (Figure 1.). The graphene film was synthesized via thermal chemical vapor deposition (CVD) process. Synthesized graphene was transferred on the core exposed region of fiber optic by lift-off method. Detected analytes were biotinylated double cross-over DNA structure (DXB) and Streptavidin (SA) as the ligand-receptor binding model. The preliminary results showed the SPR signal shifts for the DXB and SA binding rather than the concentration change.

• 센서학회지
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• 제19권6호
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• pp.456-461
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• 2010

The detection of C-reactive protein(CRP) using self-assembled monolayer(SAM) was investigated by a portable surface plasmon resonance(SPR) sensor system. The CRP is a biomarker for the possible cardiovascular disease. The SAM was formed on gold(Au) surface to anchor the monoclonal antibody of CRP(anti-CRP) for detection of CRP. Sequence injection of the anti-CRP and bovine serum albumin(BSA) into the sensor system has been carried out immobilize the antibody and to prevent non-specific binding. The portable SPR system has two flow channels: one for the sample measurements and the other for the reference. The output SPR signal was increased with the injection of the anti-CRP, BSA and CRP due to binding of the proteins on the sensor chip. The valid output SPR signals was linearly related to the critical range of the CRP concentration. The experimental results showed the feasibility of the portable SPR system with newly developed SAM to diagnose a risk of the future cardiovascular events.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.257-270
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• 2013

The use of lightweight materials has been steadily increasing in the automotive industry, and presents new challenges to material joining. Among many joining processes, self-piercing riveting (SPR) is particularly promising for joining lightweight materials (such as aluminum alloys) and dissimilar materials (such as steel to Al, and metal to polymer). However, to establish a process window for optimal joint performance, it often requires a long trial-and-error testing of the SPR process. This is because current state of the art in numerical analysis still cannot effectively resolve the problems of severe material distortion and separation in the SPR simulation. This paper presents a coupled meshfree/finite element with a moving boundary algorithm to overcome these numerical difficulties. The simulation results are compared with physical measurements to demonstrate the effectiveness of the present method.

• 한국기계가공학회지
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• 제20권5호
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• pp.76-84
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• 2021

In this study, an optimal stiffness model of the C-frame, which was supporting the mold and tool load, was proposed to obtain quality self-piercing riveting (SPR) joining. First, the load path acting on the C-frame structure was identified using topology optimization. Then, a final suggested model was proposed based on the load path results. Stiffness and strength analyses were performed for a rivet pressing force of 7.3 [t] to compare the design performance of the final proposed model with that of the initial model. Moreover, to examine the reliability of continuous and repeated processes, vibration analysis was performed and the dynamic stiffness of the final proposed model was reviewed. Additionally, fatigue analysis was performed to ascertain the fatigue characteristics due to simple repetitive loading. Finally, stiffness test was performed for the final proposed model to verify the analysis results. The obtained results differed from the analysis result by 2.9%. Consequently, the performance of the final proposed model was superior to that of the initial model with respect to not only the SPR fastening quality but also the reliability of continuous and repetitive processes.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.780-786
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• 2002

An immunosensor based on surface plasmon resonance (SPR) with a self-assembled protein G layer was developed for the detection of Escherichia coli O157:H7. A self-assembled protein C layer on a gold (Au) surface was fabricated by adsorbing the mixture of 11-mercaptoundecanoic acid (MUA) and hexanethiol at various molar ratios and by activating chemical binding between free amine (-$NH_2$) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) in series. The formation of a self-assembled protein G layer on an Au substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The surface morphology analyses of the self-assembled protein G layer on the Au substrate, monoclonal antibody (Mab) against E. coli O157:H7 which was immobilized on protein G, and bound E. coli O157:H7 extracts on Immobilized Mab against E. coii O157:H7 were performed by atomic force microscopy (AFM). The detection limit of the SPR-based immunosensor for E. coli O157:H7 was found to be about $10^4$ cells/ml.

• Journal of Biosystems Engineering
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• 제29권4호
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• pp.323-328
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• 2004

A surface plasmon resonance (SPR) sensing system, which belonged to a family of thin film refractometry-based sensors, was fabricated to measure the alcohol contents in alcoholic beverages. In this study, a SPR owe was obtained by a photodiode array with 128 pixels and transformed into a refractive index which was calculated by means of the first moment of values below a baseline of 0.85. When the sensing system was applied to Soju, Cheonju, Igwaduju and Tacju highly linear relationships between the refractive index by SPR and the contents of alcohol were obtained. That is, the coefficients of determination in their linear models were 0.992, 0.933, 0.918 and 0.954, respectively. Meanwhile, the effect of sample preparations on the accuracy of measurement was analyzed. As for Soju and Tacju, the best calibration equations were obtained when no sample preparation was applied. The best calibration models for measurement of Cheonju and Igwaduju were obtained through the samples filtered by $C_{18}$ disks.

• 한국전기전자재료학회논문지
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• 제25권7호
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• pp.516-520
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• 2012

In this paper, we have theoretically analyzed and designed a dielectric multi-layer sensor with a SPR (surface plasmon resonance) using analytical calculation and FDTD (finite difference time-domain) methods. The proposed structure is composed of periodic layer and thin metal film. It has many advantages. One of that is a high sensitivity of the SPR. Another is a high Q-factor of the characteristics in the PhC (photonic crystals) micro-cavity structure. The incident light has double resonance characteristics, because the filtered light by PhC structure, dielectric multi-layer, is met the thin metal film for SPR effect. We have also observed the change of resonance characteristics according to the variation of effective index on the metal film.