• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.2114-2116
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• 2004

센서의 소형화 되는 추세에 전극 면적은 sensitivity의 중요한 요인이다. 본 연구에서는 콜레스테롤을 측정하기 위해 각각 planar 전극과 porous 전극에 효소 고정화 방법으로 covalent binding인 silanization 공정을 이용하여 전극 면적에 따른 전기화학적 감도를 비교하였다. Handles-Sevcik equation을 이용하여 전극 면적을 구한 결과 planar 전극의 경우 0.1608 $cm^2$, porous 전극의 경우 0.5054 $cm^2$로 porous 전극 면적이 planar전극에 비해 약 3.1배 증가하였다. 또, planar 센서의 sensitivity는 0.08567 ${\mu}A/mM{\cdot}cm^2$이고 porous 센서의 sensitivity는 planar sensor에 비해 약 3.1배 증가한 0.2656 ${\mu}A/mM{\cdot}cm^2$였다. 따라서 porous sensor의 sensitivity의 증가는 전극 면적의 증가에 따른 것이라고 할 수 있다.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2171-2175
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• 2013

The electronic structure and elastic properties of the 4d transition metal carbides MC (M = Y, Zr, Nb, Rh) were studied by means of extended H$\ddot{u}$ckel tight-binding band electronic structure calculations. As the valence electron population of M increases, the bulk modulus of the MC compounds in the rocksalt structure does not increase monotonically. The dominant covalent bonding in these compounds is found to be M-C bonding, which mainly arises from the interaction between M 4d and C 2p orbitals. The bonding characteristics between M and C atoms affecting the variation of the bulk modulus can be understood on the basis of their electronic structure. The increasing bulk modulus from YC to NbC is associated with stronger interactions between M 4d and C 2p orbitals and the successive filling of M 4d-C 2p bonding states. The decreased bulk modulus for RhC is related to the partial occupation of Rh-C antibonding states.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3722-3726
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• 2013

Covalent functionalization of a $Zn_{12}O_{12}$ nano-cage with $CO_2$ molecule in terms of energetic, geometry, and electronic properties was investigated by density functional theory method. For chemisorption configurations, the adsorption energy of $CO_2$ on the $Zn_{12}O_{12}$ nano-cage for the first $CO_2$ was calculated -1.25 eV with a charge transfer of 1.00|e| from the nano-cage to the $CO_2$ molecule. The results show that $CO_2$ molecule was significantly detected by pristine $Zn_{12}O_{12}$ nano-cage, therefore the nano-cage can be used as $CO_2$ storage. Also, more efficient binding could not be achieved by increasing the $CO_2$ concentration. For Physisorption configurations, HOMO-LUMO gap of the configurations has not changed, while slight changes have been observed in the chemisorption configurations.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권4호
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• pp.263-267
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• 2003

Magnetic nanoparticles prepared from an alkaline solution of divalent and trivalent iron ions could covalently bind protein via the activation of Nethyl-N-(3-dimethylaminopropyl) carbodiimide (EDC). Trypsin and avidin were taken as the model proteins for the formation of protein-nanoparticle conjugates. The immobilized yield of protein increased with molar ratio of EDC/nanoparticie. Higher concentrations of added protein could yield higher immobilized protein densities on the particles. In contrast to EDC, the yields of protein immobilization via the a ctivation of cyanamide were relatively lower. Nanoparticles bound with avidin could attach a single-stranded DNA through the avidin-biotin interaction and hybridize with a DNA probe. The DNA hybridization was confirmed by fluorescence microscopy observations. Immobilized DNA on nanoparticles by this technique may have widespread applicability to the detection of specific nucleic acid sequence and targeting of DNA to particular cells.

• Asian-Australasian Journal of Animal Sciences
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• 제23권12호
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• pp.1668-1676
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• 2010

The somatotropic axis plays a key role in proliferation and differentiation of avian organs during both pre- and posthatching periods. This review discusses the complexity of regulation of the endocrine system for chicken development and growth by growth hormone (GH), insulin-like growth factor (IGF), and IGF binding protein (IGFBP). In addition, the thyrotropic axis, including thyrotropin-releasing hormone (TRH) and thyroid hormones ($T_4$ and $T_3$), is also involved in the GH-secreting pattern. In mammals, IGFI and -II are always sequestered in a 150 kDa non-covalent ternary complex. This complex consists of one molecule each of IGF-I or IGF-II, IGFBP-3 or IGFBP-5 and an acid labile subunit (ALS). Chick ALS is identified in different strains for the first time, and further investigation of the expression of ALS on developmental stage and ALS effect on IGF bioavailability may be addressed in the future.

• Bulletin of the Korean Chemical Society
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• 제27권4호
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• pp.479-483
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• 2006

We developed a microfluidic immunoassay platform for the detection of various analytes such as bacterial pathogen by packing antibody-immobilized glass beads in spatially-isolated microchambers on a microfluidic device. Primary amines of antibody were covalently conjugated to carboxyl-terminated glass beads previously treated with aminosilane followed by glutaraldehyde. Through this covalent binding, up to 905 $\mu$g immunoglobulin G (IgG) per gram of glass beads was immobilized. For application, glass beads attaching antibody specific to Escherichia coli O157:H7, a foodborne pathogen, were packed into a microfluidic device and used for the detection of the serotype. This prototype immunoassay device can be used for the simultaneous detection of multiple analytes by sequentially packing different-sized glass beads attaching different antibody in discrete microchambers on a single microfluidic device.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.512-518
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• 2023

To address inherent weaknesses such as low mechanical strength and limited enzyme loading capacity in conventional chitosan or alginate beads, an additional step involving the exchange of anionic surfactants with hydroxide ions was employed to prepare porous chitosan hydrogel capsules for enzyme immobilization. Consequently, excellent thermal stability and long-term storage stability were confirmed. Furthermore, coating the porous chitosan hydrogel capsules with polydopamine not only improved mechanical stability but also exhibited remarkable enzyme immobilization efficiency (97.6% for M1-D0.5). Additionally, it was demonstrated that the scope of application for chitosan hydrogel beads, prepared using conventional methods, could be further expanded by introducing an additional step of polydopamine coating. The enzyme immobilization matrix developed in this study can be selectively applied to suit specific purposes and is expected to be utilized as a support for the adsorption or covalent binding of various substances.

• Korean Chemical Engineering Research
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• 제44권3호
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• pp.254-258
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• 2006

휘발성 유기화합물을 제거하는 허니콤 흡착제의 제조 성분인 무기질 섬유에 흡착력이 뛰어난 제올라이트를 화학 결합시켰다. 무기질 섬유를 염산, 황산 또는 플루오르화 수소산 등으로 처리하여 표면의 불순물을 제거하여 제올라이트의 접합 능력을 향상시켰다. 무기질 섬유와 제올라이트의 표면에 매달은 클로로프로필, 아미노프로필 또는 에폭시기 등을 서로 반응시켜 두 물질을 화학 결합시켰으며, 연결 화합물로 고분자 폴리에틸렌이민을 사용하기도 하였다. 결합상태는 전자현미경으로 관찰하였고, BET 표면적 분석을 통하여 제올라이트 접합량을 유추하였다. 폴리에틸렌이민을 사용하면 제올라이트를 무기질 섬유에 많이 결합시킬 수 있었다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.62-62
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• 2003

The native form of serpin (serine protease inhibitor) is kinetically trapped in metastable state. Metastability in these proteins is critical to their biological function. Serpins inhibit target proteases by forming a stable covalent complex in which the cleaved reactive site loop of the serpin is inserted into $\beta$-sheet A of the serpin with concomitant translocation of the protease to the opposite of the initial binding site. Despite recent determination of the crystal structures of a Michaelis protease-serpin complex as well as a stable covalent complex, details on the kinetic mechanism remain unsolved. In this study we constructed several $\alpha$$_1$-antitrypsin variants and examined their kinetic mechanism of loop translocation and formation of protease-serpin complex by stopped-flow experiments of fluorescence resonance energy transfer as well as quenched-flow experiment. We report here the relationship of serpin's conformational switch mechanism with Inhibitory activity. There is little direct correlation between loop insertion rate and inhibitory activity. Rather, disrupting a salt bridge between R196 and E354 accelerates loop translocation even though it impairs the inhibitory activity. Moreover, the serpin's reactive site loop is translocated, at least partially, prior to loop cleavage.

• 분석과학
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• 제29권3호
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• pp.105-113
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• 2016

고정화 지지체로 사용된 실리카 나노입자와 실리카 코팅된 자성 나노입자에 작용기를 부착시켜 기능성을 부가한 후 효소인 리파아제를 고정화하여 리파아제의 안정성을 향상시키고자 연구를 수행하였다. 지지체에 부착하는 작용기가 고정화된 효소의 활성과 안정성에 미치는 영향도 살펴보았다. 실리카 나노입자와 실리카 코팅된 자성 나노입자에 부착한 작용기인 epoxy group과 amine group은 glycidyl methacrylate과 aminopropyl triethoxysilane을 통해 실리카 나노입자와 실리카 코팅된 자성 나노입자 표면에 각각 부착하였다. 작용기가 부착된 실리카 나노입자와 실리카 코팅된 자성 나노입자에 고정화한 Candida rugosa lipase는 자유효소에 비해 초기반응속도는 다소 낮았지만, 3 회 재사용한 후 측정한 활성이 최초 활성 대비 92 % 이상의 활성을 유지하였다. 또한, 실리카 코팅된 자성 나노입자에 glutaraldehyde를 이용한 cross-linked enzyme aggregate (CLEA) 방법과 공유결합법을 통해 라파아제를 각각 고정화한 연구를 수행한 결과, 실리카 나노입자와 실리카 코팅된 자성 나노입자에 CLEA 방법과 공유결합법으로 각각 고정화한 Candida rugosa lipase는 자유효소에 비해 초기반응속도 뿐만 아니라 최종 활성도 높았고, 5 회 재사용한 후 측정한 활성이 최초 활성 대비 73 % 이상의 활성을 유지하였다.