• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.268.2-268.2
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• 2013

Nanogap interdigitated electrodes (NIDEs) can serve as an alternative platform for the biomolecular detection [1]. In this work, the NIDEs were adopted in a simple and sensitive detection of Pneumococcal surface protein A (PspA). The NIDEs were fabricated by the combination of photo and chemical lithography. Photolithographically-defined initial gap of about 200 nm was narrowed down to a few tens of nanometers by surface-initiated growth of the initial electrodes (chemical lithography) [2]. Bare silicon oxide surface between the electrodes was chemically modified to immobilize capturing antibodies and, after exposure to the samples, the device was immersed in a solution containing the probe-antibody-conjugated Au nanoparticles (Au NPs). The conductance change accompanied with the Au NP immobilization was interpreted as the existence of PspA. Detection limit of the measurements and further improvement of the detection efficiency were discussed with the results from I-V analysis, scanning electron microscopy, and atomic force microscopy.

• Membrane Journal
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• v.8 no.1
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• pp.50-58
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• 1998

Protein affinity membranes were prepared via coating of chitosan gel on the porous flat and hollow-fiber polysulfone membranes, followed by the immobilization of the reactive dye (Cibacron Blue 3GA) to the chitosan gel. Maximum protein binding capacity of these affinity membranes was about 70 $\mu{g/cm}^2$. Using the affinity flat membrane module, the elution chromatography of human serum albumin (HSA) was performed to determine the optimum condition of eluent buffer. The optimum condition of eluent was the universal buffer solution of 0.06 M concentration containing 1 M KCl at pH 10. For the frontal chromatography of HSA using the flat module, the dynamic protein binding capacity was rapidly decreased from the equilibrium values with increasing flow rate and HSA concentration of the loading solution. However, in the case of hollow-fiber module, the dynamic binding capacity was maintained an equilibrium value without depending on the operating conditions. These results showed that the hollow-fiber module was more effective than the flat module as an affinity chromatography column.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.257-260
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• 2002

Dissolved oxygen level of cell culture media has a critical effect on cellular metabolism, which governs specific productivity of recombinant proteins and mammalian cell growth However, in the cores of cell aggregates or cell-immobilized beads, oxygen level frequently goes below a critical level. Mammalian cells have a number of genes induced in the lower level of oxygen, and the genes contain a common cis-acting element (-RCGTG-), hypoxia response element (HRE). By binding of hypoxia inducible factor-l (HIF-I) to the HRE, promoters of hypoxia inducible genes are activated, which is a survival mechanism. In this work, to develop a CHO cell capable of producing recombinant proteins in immobilization and high density cell culture efficiently, mammalian expression vectors containing human tissue-type plasminogen activator (t-PA) gene controlled by HRE were constructed and stably transfected into the CHO cells. In $Ba^{2+}$ -alginate immobilization culture, CHO/pCl/dhfr/2HRE-t-PA cells produced 2 folds higher recombinant t-PA activity than CHO/pCl/dhfrlt-PA cells without $CoCl_2$ treatment. Furthermore, in repeated fed batch culture, productivity of t-PA in immobilized CHO/pCI/dhfr/2HRE-t-PA cells was 121 ng/ml/day, total production of 0.968 mg/day at 11 days culture while CHO/pCIIdhfrlt-PA cells was 22.8 ng/ml/day. All these results indicate that HRE is very useful for the enhancement of protein productivity in mammalian cell cultures.

• Analytical Science and Technology
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• v.23 no.2
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• pp.172-178
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• 2010

Glutathione S-transferase is known to play a crucial role in detoxification in many cases. To develop a herbicide detection biosensor, we in this study attempted to immobilize glutathione S-transferase enzyme on solid supports, polystyrene and agarose, and Na-alginate. These matrixes were attractive materials for the construction of biosensors and might also have utility for the production of immobilized enzyme bioreactors. We also compared the activities of glutathione-S-transferase immobilized OsGSTF3 and free OsGSTF3. The specific activity of the free enzyme in solution was 3.3 higher than the immobilized enzyme. These results suggest that 50% of the enzyme was bound with the catalytic site in polystyrene-alkylamine bead and immobilized enzymes showed 80% remaining activity until 3 times reuse.

• Journal of Life Science
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• v.27 no.10
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• pp.1145-1151
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• 2017

In this study, we report on a simple, efficient method for obtaining penicillin G amidase (PGA) from recombinant Escherichia coli using a formulation mixed with detergent and lysozyme. Research was conducted on the extraction efficiency of PGA from the periplasmic space in cells in terms of the type of detergent, detergent concentration, pH, reaction time, and temperature of permeabilization. The extraction yield of PGA in the formulated surfactant/lysozyme treatment was increased by approximately (55-65 U/ml) in comparison with that in the single surfactant treatment. The released PGA solution was concentrated and exchanged with buffer using an ultrafiltration (U/F) system. The yields of diatomite filtration, membrane filtration (M/F), and U/F were 69.7%, 93.8%, and 77.3%, respectively. A total of 212 KU of PGA was recovered. At the 25-L culture scale, the overall yield of extraction using the mixed surfactant/lysozyme method was 49.2%. The specific activity of extracted PGA was 11 U/mg in protein. The concentrated PGA solution was immobilized on microporous silica beads without further purification of PGA. The total immobilization yield of PGA on the resin was 48.7%, while the enzyme activity was 101 U/g. The immobilized PGA was successfully used to produce 6-APA from penicillin G. Our results indicated that a simple extraction method from periplasmic space in E. coli may be used for the commercial scale production of ${\beta}-lactam$ antibiotics using immobilized PGA.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.546-549
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• 2000

Liposomes and proteoliposomes, artificial membranes, can interact with many solutes, such as drugs, peptides and proteins. Immobilization of (proteo)liposomes as supramolecular aggregates on gold surfaces have potential applications in nanotechnology and biosensors. We demonstrate a quartz crystal analyzer (QCA) method to monitor the construction of multi layers of unilamellar liposomes based on avidin-biotin binding on gold surface using quartz crystal microbalance(QCM). Thus, QCA provides an on line and efficient method to detect the protein membranes construction and have applications to biosensing system.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.613-616
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• 2001

The performance of five supports was evaluated for the immobilization of protease in a packed bed reactor, Celite R640, Duolite A568 and Silicagel 60 showed higher enzyme activity for column opel'ation, The optimum conditions for this operation were pH 5.0 and $50^{\circ}C$, Egg yolk protein was also hydrolyzed to obtain peptide solution in this study.

• KSBB Journal
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• v.17 no.3
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• pp.213-227
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• 2002

To date, the majority of biosensor technologies use binding components such as enzymes antibodies, nucleic acids and protein ligands. In contrast, the goal underlying the use of cells and tissues of animals and plants for a sensor system is to obtain systems capable of extracting information based on the biological activity, mechanisms of action and consequences of exposure to a chemical or biological agent of interest. These systems enable the interrogation of more complex biological response and offer the potential to gather higher information content from measuring physiologic and metabolic response. In these articles, same of the recent trends and applications of microbial biosensors in environmental monitoring and for use in food and fermentations have been reviewed. This endeavor presents many technological challenges to fabricate new microbial biosensors for other scientific field.

• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.1
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• pp.1-4
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• 2002

Silk proteins consist of two major proteins, fibroin and sericin. There is currently an enormous reawakening of interest in these silk proteins as a biomaterial due to their mechanical and biological properties based on the detailed findings. Novel method for determination of the crystalline structure of silk proteins in an atomic level using nuclear magnetic resonance (NMR) was reviewed. Recent application of silks to biomaterials and prospects for future were discussed.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.244-247
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• 2020

We have expressed extracellular poly(3-hydroxybutyrate) (PHB) depolymerase of Ralstonia pickettii T1 on the Escherichia coli surface using Pseudomonas OprF protein as a fusion partner by C-terminal deletion-fusion strategy. Surface display of depolymerase was confirmed by flow cytometry, immunofluorescence microscopy and whole cell hydrolase activity. For the application, depolymerase was used as an immobilized catalyst of enantioselective hydrolysis reaction for the first time. After 48 h, (R)-methyl mandelate was completely hydrolyzed, and (S)-mandelic acid was produced with over 99% enantiomeric excess. Our findings suggest that surface displayed depolymerase on E. coli can be used as an enantioselective biocatalyst.