• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.305-309
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• 2010

Photopolymer films containing fluorescent anthracene polymer, polymethyleneanthracene (PMAn), were prepared with different concentrations of PMAn for holographic recording useful for security documents. The fluorescent photopolymer film showed enhanced fluorescent intensity due to the micro-separation which arose from grating formation and diffusion during photopolymerization. Experimental values of diffraction efficiency were well matched to the simulated values for photopolymers having different PMAn concentrations. Holography patterning was carried out using the fluorescent photopolymer under a photo-mask. A grating was confirmed using microscope techniques in the recorded area under the pattern. Importantly the recorded area showed enhanced fluorescence compared to the unrecorded part, allowing fluorescence patterns at micro scale along with the submicron grating pattern. The fluorescence pattern recorded on the photopolymer film provides additional readability of holographic reading and thus is useful for secure recording and reading of information.

• Macromolecular Research
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• v.12 no.5
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• pp.493-500
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• 2004

We have developed a novel method for patterning functional images in thin polymer films. The key materials we utilized for the imaging were dihydroxyanthraquinones protected with acid-labile tert-butoxycarbonyl (t-Boc) blocking groups. Among the tested compounds, 1,4-dihydroxyanthraquinone (quinizarin; 1) underwent the most drastic change in terms of its color and fluorescence upon protection. We prepared the t-Boc-protected quinizarin and polymers bearing the protected quinizarins as pendent groups. To investigate the possibility of a single-component imaging system, we synthesized a styrenic monomer 14 incorporating protected quinizarin and a maleimide derivative 15 bearing a photoacid generating group and subjected them to polymerization. Selective removal of the protecting groups of the quinizarin moieties in the exposed area using photolithographic techniques allowed regeneration of quinizarin and patterned fluorescence images in the polymer films.

• Polymer(Korea)
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• v.32 no.1
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• pp.56-62
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• 2008

Three types of network polyesters have been newly synthesized by a two-step condensation reaction by the various combination of several diols and diacids. When these polymer films were thermally treated at $240^{\circ}C$, they exhibited absorptions in a visible range despite the forbidden transition of carbonyl group. When excited at wavelengths above 330 nm, the polymers showed fluorescences in a wide visible range from blue to near yellow. These fluorescence phenomena are due to the formation of certain conjugated structures by the Knoevenagel type self-condensation under the high-temperature thermal treatment. These polymers showed significant difference in the thermal properties as a function of the degrees of chemical crosslinking. They also underwent photodegradation. Highly resolved, fluorescent image patterns were successfully obtained by the photodegradation of malonate group under a strong UV-light irradiation.

• ALGAE
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• v.19 no.2
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• pp.79-90
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• 2004

Nuclear DNA contents of spermatia from eight ceramiacean and four dasyacean algae (Ceramiales, Rhodophyta) and microspores from two land plants were estimated by fluorescence microscopic image processing and their nuclear SSU rDNA sequence data were analyzed. In frequency distribution patterns, the DAPI-stained nuclear volume (NV) of spermatia showed two peaks corresponding to 1C and 2C. Nuclear 2C DNA contents estimated from NV were 0.45-2.31 pg in ceramiacean and 0.40-0.57 pg in dasyacean algae and 8.42-9.51 pg in two land plants, Capsicum annuum and Nicotiana tabacum. By nuclear patterning of vegetative cells derived from an apical cell, 2C DNA contents of spermatia were 2.31 pg in an alga having uninucleate and non-polyploid nucleus (Aglaothamnion callophyllidicola), 0.45-1.94 pg in algae having uninucleate and polyploid nucleus (Antithamnion spp. and Pterothamnion yezoense), and 0.40-0.62 pg in algae having multinucleate and non-polyploid nuclei (Griffithsia japonica and dasyacean algae). Each mature spermatium and microspore (pollen grain) seemed to have a 2C nucleus, which may provide a genetic buffering system to protect the genetic content of a spermatium and microspore from potentially lethal mutations. Nuclear DNA content and SSU rDNA sequence of Antithamnion sparsum from Korea were reasonably different from those of Antithamnion densum from France. The data did not support the previous taxonomic studies that these two taxa could be conspecific.

• Macromolecular Research
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• v.16 no.5
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• pp.385-395
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• 2008

Synthesis and properties of novel excited-state intramolecular proton transfer (ESIPT) materials, recently developed in our group, are described. Highly efficient ESIPT reaction, achieved in polyquinolines, polybenzoxazoles, and oxadiazole and imidazole derivatives possessing an intramolecular tautomerizable hydrogen bond, has been investigated theoretically and experimentally. It is demonstrated that unique properties arising from the ESIPT process (large Stokes' shift, no self-absorption, and easy population inversion, etc.) make it possible to produce advanced polymer devices for lasing, optical storage, and electroluminescence.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1219-1220
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• 2015

마이크로, 나노유체 (micro-, nanofluidics)을 이용한 종이 기반 분석 소자 (paper-based analytical devices, micro-PADs)에 대한 관심이 증가하고 있다. 종이 기반의 분석 소자는 초저가의 비용과 간단한 공정 방법으로 인하여 상용화 컨셉의 바이오센서로 각광받고 있다. 하지만, 종이 기반의 분석 소자는 낮은 검출 한계 (limit of detection, LOD)와 민감도 (sensitivity)의 제한이 있다. 그로 인해 우리는 이온 선택적 투과층 (ion permselective membrane, i.e. Nafion)을 종이 기반의 분석 소자와 결합하여 이온 농도 분극 (ion concentration polarization, ICP) 현상을 구현하여 낮은 검출한계와 민감도를 개선할 수 있었다. 접착력이 있는 테이프 표면에 이온 선택적 투과층을 패터닝 (patterning)하여 종이 기반 분석 소자와 결합하여 매우 간단하게 소자를 제작할 수 있었다. 따라서 종이 기반의 채널 양단에 직류 전압을 인가했을 때 발생하는 ICP 현상으로 인하여 형광 물질 (fluorescence dye)이 농축(preconcentration)되는 것을 확인할 수 있었다. 구체적으로, 초기 농도가 1.55 nM인 형광 물질을 이용하여 200 V의 외부전압을 인가했을 때, 500 초 이내에 1000 배 이상의 농축비를 얻을 수 있었다. 따라서, 외부 전압을 상용화된 건전지 출력값으로 낮출 수 있다면 다양한 종이 기반 분석 소자와 간단한 결합 방법을 통해 상용화 컨셉의 바이오센서로도 구현이 가능할 것이다.

• Journal of Life Science
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• v.10 no.2
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• pp.218-227
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• 2000

Bone morphogenetic protein 1 (BMP-1) is part of a complex capable of inducing ectopic bone formation in mammals. Studies on TGF-β1 processing and Drosophila dorsal-ventral patterning have focused attention on BMP-1 as important in mediating the biological activity of this bone inducing complex. Herein, the bacterial expression, refolding, purification, and initial characterization of the BMP-1 proteolytic domain (BPD) are described. A semi-quantitative fluorescence-based thin layer chromatography assay was developed to assist in rapidly screening for optimal renaturation conditions. According to a preliminary screen for optimal conditions for the refolding of BPD , a detectable proteolytic activity against a high turnover substrate for astacin, a homologous protease from crayfish was observed. The conditions identified have allowed the expression of sufficient amounts of BPD for the characterization of the protein. Its proteolytic activity exhibits the same cleavage specificity as astacin against seven substrates that were previously synthesized for studying astacin. Furthermore, this activity is inhibited by the metal chelator 1,10-phenanthroline but not by its analogue 1,7-phenanthroline. The collagenase inhibitor Pro-Leu-Gly hydroxamate was found to inhibit both astacin and BPD activity. The results presented in this paper argue that BMP-1 does in fact possess an intrinsic proteolytic activity.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.274-279
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• 2007

This study focuses on the enhancement of maskless photolithography as well as the peptide synthesis application with single crystalline silicon micromirrors. A single crystalline silicon micromirror array has been designed and fabricated in order to improve its application to the peptide synthesis. A micromirror rotates about ${\pm}\;9^{\circ}$ at the pull-in voltage, which can range from 90.7 V to 115.1 V. A $210\;{\mu}m-by-210\;{\mu}m$ micromirror device with $270\;{\mu}m$ mirror pitch meets the requirements of an adequately precise separation for peptide synthesis. Synthetic 16 by 16 peptide array corresponds to the same number of micromirrors. The large size of peptide pattern and the separation facilitate biochip experiments using fluorescence assay. The peptide pattern has been synthesized on the GPTS-PEG200 surface with BSA-blocking and thereupon the background was acetylated to reject non-specific bindings. Hence, an averaged slope at the pattern edge has been distinguishably improved in comparison to patterning results from an aluminum micromirror.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.137-142
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• 2004

In this study, a simple procedure is described for patterning biotin on a glass substrate and then selectively immobilizing proteins of interest onto the biotin-patterned surface. Microcontact printing (CP) was used to generate the micropattern of biotin and to demonstrate the selective immobilization of proteins by using enhanced green fluorescent protein (EGFP) as a model protein, of which the C-terminus was fused to a core streptavidin (cSA) gene of Streptomyces avidinii. Confocal fluorescence microscopy was used to visualize the pattern of the immobilized protein (EGFP-cSA), and surface plasmon resonance was used to characterize biological activity of the immobilized EGFP-cSA. The results suggest that this strategy, which consists of a combination of $\mu$CP and cSA-fused proteins. is an effective way for fabricating biologically active substrates that are suitable for a wide variety of applications. one such being the use in protein-protein assays.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.74-78
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• 2003

Multi-channel images of 11-MUA and 11-MUOH self-assembled monolayers were obtained by using two-dimensional surface plasmon resonance (SPR) absorption. Patterning process was simplified by exploiting direct photo-oxidation of thiol bonding (photolysis) instead of conventional photolithography. Sharper images were resolved by using a white light source in combination with a narrow bandpass filter in the visible region, minimizing the diffraction patterns on the images. The line profile calibration of the image contrast caused by different resonance conditions at each points on the sensor surface (at a fixed incident angle) enables us to discriminate the monolayer thickness in sub-nanometer scale. Furthermore, there is no signal degradation such as photo bleaching or quenching which are common in the detection methods based on the fluorescence.