• Biotechnology and Bioprocess Engineering:BBE
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• 제9권2호
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• pp.112-117
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• 2004

The performance of an immuno-analytical system can be assessed in terms of its analytical sensitivity, i.e., the detection limit of an analyte, which is determined by the amount of analyte molecules bound to the capture antibody that has been immobilized onto a solid surface. To increase the number of the binding complexes, we have investigated a site-directed immobilization of an antibody that has the ability to resolve a current problem associated with a random arrangement of the insolubilized immunoglobulin. The binding molecules were chemically reduced to produce thiol groups that were limited at the hinge region, and then, the reduced products were coupled to biotin. This biotinylated antibody was bound to a streptavidin-coated surface via the streptavidin-biotin reaction. This method can control the orientation of the antibody molecules present on a solid surface and also can significantly reduce the possibility of steric hindrance in the antigen-antibody reactions. In a two-site immunoassay, the introduction of the site-directly immobilized antibody as the capture enhanced the sensitivity of analyte detection approximately 10 times compared to that of the antibody randomly coupled to biotin. Such a novel approach would offer a protocol of antibody immobilization in order for the possibility of constructing a high performance immunochip.

• Biomolecules & Therapeutics
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• 제18권2호
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• pp.184-190
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• 2010

Clinical cases of pure red cell aplasia (PRCA) have been reported during the recombinant human erythropoietin (EPO) therapy for the anemia patients. PRCA is a rare hematological disorder leading to a severe anemia due to an almost complete stop of red blood cell production. Antibody (Ab)-associated PRCA is caused by the EPO-neutralizing Abs that eliminate the biological activity of EPO. In order to detect anti-EPO Abs in human sera, we performed conventional ELISA, directly coated bridging ELISA, and streptavidin coated bridging ELISA, and compared their sensitivity and specificity. Some false positive results were obtained in the conventional ELISA. One positive sample was detected successfully by streptavidin coated bridging ELISA, which was not appeared in the directly coated bridging ELISA. In conclusion, streptavidin coated bridging ELISA was substantially sensitive and specific format and one out of sixty-eight serum samples was proved to be anti-EPO positive.

• 센서학회지
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• 제15권4호
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• pp.237-244
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• 2006

Atomic force microscope (AFM) has become a common tool for the structural and physical studies of biological macromolecules, mainly because it provides the ability to perform experiments with samples in a buffer solution. In this study, structure of proteins and nucleic acids has been studied in their physiological environment that allows native intermolecular complexes to be formed. Cr and Au were deposited on p-Si (100) substrate by thermal evaporation method in sequence with the thickness of $200{\AA}$ and $500{\AA}$, respectively, since Au is adequate for immobilizing biomolecules by forming a self-assembled monolayer (SAM) with semiconductor-based biosensors. The SAM, streptavidin and biotin interacted each other with their specific binding energy and their adsorption was analyzed using the Bio-AFM both in a solution and under air environment. A silicon nitride tip was used as a contact tip of Bio-AFM measurement in a solution and an antimony doped silicon tip as a tapping tip under air environment. Actual morphology could also be obtained by 3-dimensional AFM images. The length and agglomerate size of biomolecules was measured in stages. Furthermore, $R_{a}$ (average of surface roughness) and $R_{ms}$ (mean square of surface roughness) and surface density for the adsorbed surface were also calculated from the AFM image.

• 대한핵의학회지
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• 제36권2호
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• pp.133-139
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• 2002

목적: 섬광 근접측정법은 항원 항체 반응 후 결합 분획과 유리분획을 분리하는 과정이 필요없다. 이러한 원리를 검체 내 hCG와 항 ${\alpha}$ hCG 항체간의 항원 항체 반응에 적용하고자 한다. 대상 및 방법: 항 ${\alpha}$ hCG 항체를 biotin과 결합시켜 SPA bead에 부착된 streptavidin과 부착 가능하게 만들었다. 이 측정법은 항 ${\alpha}$ hCG 항체가 부착된 SPA beads에 대해 혈청내 hCG와 표지항원인 $[^{125}I]hCG$간의 경쟁 반응을 기본 원리로 이용하였다. Biotin 표지 항 ${\alpha}$ hCG 항체를 $[^{125}I]hCG\;100{\mu}{\ell}$와 표준용액이나 환자 혈청 $200{\mu}{\ell}$이 들어있는 실온에서 20분 방치하였다. 그리고 streptavidin이 붙은 SPA beads $20{\mu}{\ell}$를 바이알에 넣고 10분 더 방치한다. 환자 혈청의 수치를 표준 응답곡선을 통해 계산하였다. 결과: SPA측정법에 사용되는 방사성 핵종의 방사능 양에 따라 반응용액 속에서 SPA bead와 자유 방사성 핵종에 의한 배후 방사능이 측정값에 영향이 없음을 확인하였다. SPA 방법을 응용한 측정에서 적합한 표준 응답곡선을 얻었고, 실제 환자혈청에서의 hCG 농도를 결정할 수 있었다. 결론: 이 실험을 통해 SPA 방법을 이용한 측정법이 임상진단에 유용하게 사용될 수 있을 것으로 사료된다.

• 한국식품과학회지
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• 제30권6호
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• pp.1273-1278
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• 1998

Biotin의 분석에 사용되는 기존의 미생물 분석법보다 신속하고 간편한 효소-단백질결합 분석법(enzyme protein binding assay; EPBA)을 개발하였다. Biotin-KLH conjugate와 streptavidin을 이용한 EPBA에서, biotin의 활성을 갖는 biocytin에 대하여 각각 109% $(IC_{50}=0.3\;ppb)$와 197% $(IC_{50}=0.8\;ppb)$의 교차반응을 보였으나 desthiobiotin과 diaminobiotin 그리고 2-iminobiotin에서는 교차반응을 보이지 않았다. Streptavidin과 biotin-KLH conjugate를 이용한 EPBA에서 검출범위는 각각 $0.01{\sim}30\;ng/mL$과 $0.01{\sim}1.0\;ng/mL(ppb)$로 나타났다. 우유시료와 과일 플레이크 그리고 당근-파인애플 쥬스에 대한 spike test에서 EPBA(biotin-KLH conjugate)와 미생물 분석법(microbiological assay; MBA)간의 상관관계는 r=0.994로 매우 높은 것으로 나타났다. 그러나 MBA는 biocytin과 desthiobiotin에 대하여 각각 80.1%, 66.7%의 교차반응을 나타냈다. 검출범위도 $0.1{\sim}0.5\;ng/mL(ppb)$로 분석 범위가 매우 제한되어 있었다. 그러므로 EPBA에 의하여 biotin을 분석하는 것이 기존의 미생물 분석법에 비하여 검출 감도나 검출 범위, 교차반응 그리고 분석시간 등의 여러 가지 면에서 우수한 것으로 확인되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.494-494
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• 2005

• 한국진공학회:학술대회논문집
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• 한국진공학회 2006년도 제30회 학술논문발표회 초록집
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• pp.92-92
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• 2006

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.81-82
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• 2003

We have developed the method for the conjugation of biotinylated DNA to streptavidin-coated QDs. QD-DNA conjugates and a high-sensitive fluorescence imaging technique are adopted to visualize gene transport across the membrane of the live cell in real time. Endocytotic cellular uptake of oligonucleotide and electrically-mediated plasmid DNA transfer into the live cell are monitored by a quantitative microscopic imaging system. Long-term kinetic study enables us to reveal the unknown mechanisms and rate-limiting steps of extracellular and intracellular transport of biomolecules. We designed experimental protocols to conjugate the oligonucleotide or the plasmid DNA to commercially available streptavidin-coated QDs. Gel electrophoresis is used to verify the effect of incubation time and the molar ratio of QDs and DNA on the conjugation efficiency. It is possible to fractionate the QD-DNA conjugates according to the DNA concentration and obtain the purified conjugates by a gel extraction technique.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.2006-2007
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• 2002

MEMS 공정을 이용하여 $SiN_x$를 지지층으로 한 $SiO_2$/Ta/PZT/Pt 의 박막 구조를 가지는 마이크로 켄틸레버를 제작하였다. 켄틸레버의 전기기계적 특성을 LDV (레이저 미소 변위 측정기)를 이용하여 측정하였으며, 이를 통해 전기기계적 거동을 분석하였다. 또한 무게 감지소자로서의 응용을 위해 Au의 증착을 통한 감도를 측정하였으며, streptavidin의 무게를 감지하기 위해 immobilization 공정을 거쳐 thiol 그룹 및 biotin을 표면에 고정화 시킨후 biotin-streptavidin 결합에 의한 전기기계적 신호 분석을 통해 생체 물질의 무게 감지 소자로의 응용을 평가하였다.