• KSBB Journal
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• v.13 no.6
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• pp.693-699
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• 1998

The relationship between bioluminescence of immobilized Photobacterium phosphoreum and toxic substances was investigated to monitor toxic substances in aqueous solution. The sodium alginate was used as an immobilization matrix. A bioluminescence intensity was maximum when OD660 for cell concentration were between 1.0 and 1.2 and the biolumescence was stable at the pH range of between 6.0 and 8.0. The optimum concentration of alginate for immobilization was found to be 5.0%(w/v) in which dilution was carried out with 2.5%(w/v) NaCl solution that is an optimum environmental condition for the growth of P. phosphoreum. The bioluminescence intensity responded against the toxic substances was proportional to the concentration and a regression curve were established with linearity by using specific bioluminescence reduction rate and Gamma values. It was also found that the response was very rapid and sensitive. The response with such rapidity and sensitivity is a very important factor for the real time monitoring. The immobilized cells showed higher sensitive response to the toxic substances than free cells.

• Korean Journal of Food Science and Technology
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• v.16 no.3
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• pp.267-272
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• 1984

${\beta}-Fructofuranosidase$ was immobilized covalently on the oxidized microbial wall of a Penicillium spp. 'PS-8', which is totally different from the conventional whole cell immobilization in concept. The immobilization of ${\beta}-fructofuranosidase$ by a series of treatments; oxidation of microbial cells with sodium metaperiodate, enzyme loading on the oxidized cells, extrusion, and crosslinking induced by glutaradehyde, were carried out. The final product had a good mechanical strength and showed 26% of the applied enzyme activity. The specific activity was 750 units per g of the dry cell product. The immobilized enzyme showed the kinetic parameters as follows; optimum pH at 5, optimum temperature at $55^{\circ}C$, activation energy of 19 kJ $mol^{-1}$, and apparent Km of 55 mM.

• Tissue Engineering and Regenerative Medicine
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• v.15 no.6
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• pp.761-769
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• 2018

BACKGROUND: Bioprinting has recently appeared as a powerful tool for building complex tissue and organ structures. However, the application of bioprinting to regenerative medicine has limitations, due to the restricted choices of bio-ink for cytocompatible cell encapsulation and the integrity of the fabricated structures. METHODS: In this study, we developed hybrid bio-inks based on acrylated hyaluronic acid (HA) for immobilizing bio-active peptides and tyramine-conjugated hyaluronic acids for fast gelation. RESULTS: Conventional acrylated HA-based hydrogels have a gelation time of more than 30 min, whereas hybrid bio-ink has been rapidly gelated within 200 s. Fibroblast cells cultured in this hybrid bio-ink up to 7 days showed >90% viability. As a guidance cue for stem cell differentiation, we immobilized four different bio-active peptides: BMP-7-derived peptides (BMP-7D) and osteopontin for osteogenesis, and substance-P (SP) and Ac-SDKP (SDKP) for angiogenesis. Mesenchymal stem cells cultured in these hybrid bio-inks showed the highest angiogenic and osteogenic activity cultured in bio-ink immobilized with a SP or BMP-7D peptide. This bio-ink was loaded in a three-dimensional (3D) bioprinting device showing reproducible printing features. CONCLUSION: We have developed bio-inks that combine biochemical and mechanical cues. Biochemical cues were able to regulate differentiation of cells, and mechanical cues enabled printing structuring. This multi-functional bio-ink can be used for complex tissue engineering and regenerative medicine.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.1-8
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• 1996

A one-stage, continuous-flow bioreactor with both immobilized and suspended cells was used to investigate the roles of lipid supplements in ethanol production by Saccharomyces cerevisiae. The reactor performance and the level of alcohol dehydrogenase(ADH) activities of the suspended cells, grown under various conditions, were measured. When ergosterol and/or oleic acid were added with surfactants to the yeast culture grown under non-aerated conditions, remarkable increases in ethanol production and cell growth was achieved, but specific ADH activities were not affected. Especially, no difference of specific ADH activities of the suspended cells grown under aerated and non-aerated condition was observed. The addition of the surfactant as a supplement also resulted in significant increases in ethanol production, cell growth, and specific ADH activity. When ergosterol and oleic acid were added to the yeast culture exposed to higher ethanol concentration($>40\;g/{\ell}$) level, ethanol production, cell growth, and specific ADH activity were increased, but the addition of surfactant was as effective as at lower ethanol concentration level. The results indicated that lipid supplements were more effective at higher ethanol concentration level than at lower ethanol concentration level during ethanol production. ADH isozyme patterns of the yeast cultures grown under various conditions on starch gel electrophoresis showed only one major band, probably ADH I. The migrating distance of the major isozyme, however, varied slightly according to the culture conditions of the cells. No apparent correlation was found between specific ADH activity and amount of ethanol produced. Cell mass was more important factor for ethanol production than specific ADH activity of the cells.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.635-638
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• 2003

For the acute assessment on biological toxicity of wastewater, surface plasmon resonance(SPR) based cell viability detection was performed using gold surface-confined cell as a result of adhesion-modifying chemicals. Escherichia coli O157:H7 (E. coli O157:H7) was investigated after exposure to EDTA. Cells were immobilized on gold coated slide glass for SPR analysis by the method of cross-linking carboxyl group on the bacterial surface with amine group of poly-L-lysine that had been coupled to the gold surface modified by a self-assembled monolayer of 11-mercaptounde canoic acid (11-(MUA)). Reflective intensity of each flow step was changed with respect to confect of ethylenediaminetetraacetic acid (EDTA) disodium salt and phosphate-buffered saline (PBS) solution. The proposed detection technique can be used for biological toxicity test.

• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.156-159
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• 2005

Liposomes are microscopic spherical vesicles that form when lipids are hydrated and have been widely used for biochemical assay, drug delivery and molecular imaging. In particular, they are well known for artificial cell membranes to study cellular functions such as cell fusions and membrane proteins. Here, we firstly report the detection of liposomes by the highly sensitive microfabricated piezoresistive cantilever sensor chip and the phosphatidylserine recognition protein C2A which is chemically immobilized on the sensor surface. The signal created from the bending motion of piezoresistive cantilever after the liposome attachment has been monitored in real time.

• The Journal of the Korean dental association
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• v.11 no.3
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• pp.195-198
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• 1973

The authors have treated a squamous-cell carcinoma occurred in molar region of the right mandible in 52-year old woman by means of bony resection and banked tibial bone graft, and made the normal appearance of her face. The result as follow: 1) The healing of a graft is similar to the healing of an uninfected fracture except that it will take considerably longer. It is of the utmost importance that it should be well immobilized, otherwsie there is danger of absorption of bone and fibrous union. 2) Until the graft acquires a blood supply it is easily infected, for it has no defence against organisms, so it is most important to prevent wound infection set in.

• Journal of Chest Surgery
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• v.26 no.2
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• pp.80-85
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• 1993

Synthetic and biosynthetic vascular grafts of small diameter have long been considered to be prone to thrombosis, ultimately leading to the complete graft occlusion. Endothelial cell seeding onto synthetic blood-contacting surfaces has been suggested to be an ideal means to solve this problem. This study described a culture method of bovine endothelial cells and evaluated blood-compatibility and seeding efficiency of cultured endothelial cells. Bovine pulmonary artery endothelial cells were harvested enzymatically and grown to confluence on polystyrene culture flask surfaces using established techniques. The identification of endothelial cells was made through the demonstration of expression of factor VIII R:Ag by immunofluorescent technique. To quantitate the effect of improvement in blood-compatibility of viable endothelial cells, endothelial monolayers were exposed to blood containing $\^$111/In-oxine labeled platelets. Viable endothelial monolayers retained less labeled platelets than control surfaces. The Indium-labeled endothelial cells were seeded onto three different blood-contacting surfaces of Dacron vascular graft immobilized in specially equipped wells and incubated for specific time intervals (t=15, 30, 60, 120 minutes). Longer incubation times showed improved cell adherence in collagen-coated and fibrin-coated Dacron vascular graft groups. However in untreated Dacron grafts, no direct relationship was observed between incubation time and endothelial cell seeding efficiency. This may be due to leakage of endothelial cells through porosity of Dacron grafts in this in-vitro experimental condition.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.3
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• pp.163-174
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• 2014

The objective of this study is to prepare an artificial extracellular matrix (ECM) for cell culture by using polymer hydrogels. The polymer used is a cytocompatible water-soluble phospholipid polymer: poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-n-butyl methacrylate-p-nitrophenyloxycarbonyl poly(ethylene oxide) methacrylate (MEONP)] (PMBN). The hydrogels are prepared using a cross-linking reaction between PMBN and diamine compounds, which can easily react to the MEONP moiety under mild conditions. The most favorable diamine is the bis(3-aminopropyl) poly(ethylene oxide) (APEO). The effects of cross-linking density and the chemical structure of cross-linking molecules on the mechanical properties of the hydrogel are evaluated. The storage modulus of the hydrogel is tailored by tuning the PMBN concentration and the MEONP/amino group ratio. The porous structure of the hydrogel networks depends not only on these parameters but also on the reaction temperature. We prepare a hydrogel with $40-50{\mu}m$ diameter pores and more than 90 wt% swelling. The permeation of proteins through the hydrogel increases dramatically with an increase in pore size. To induce cell adhesion, the cell-attaching oligopeptide, RGDS, is immobilized onto the hydrogel using MEONP residue. Bovine pulmonary artery endothelial cells (BPAECs) are cultured on the hydrogel matrix and are able to migrate into the artificial matrix. Hence, the RGDS-modified PMBN hydrogel matrix with cross-linked APEO functions as an artificial ECM for growing cells for applications in tissue engineering.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.110-111
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• 2013

FcBP consisting of 13 amino acids specifically binds to Immunoglobulin G Fc domain. Initially, we utilized this peptide for preparation of antibody chip as a PEG composite for enhanced solubility. After then, the peptide conjugate was immobilized on agarose resin, resulting in highly efficient affinity column for antibody purification. The efficiency was comparable to commercial Protein A column. Recently, this peptide was conjugated with cell penetrating peptide (CPP) on a backbone of GFP, affording antibody transducer, which carries antibody into live cells by simple mixing of antibody and the transducer in cell culture media. Antibody transduction into cells was monitored by live cell imaging. More recently, the FcBP was fused to ferritin cage, which consists of 24 ferritin protein molecules. The FcBP-ferritin cage showed greatly increased binding affinity to human IgG. Its binding was analyzed by QCM and SPR analysis. Finally, it was selectively delivered by Herceptin to SKBR3, a breast cancer cell, over MCF10A, non-tumorigenic cells (Fig. 1). Fig. 1. Fluorescent microscopic images of SKBR3 breast cancer cells (A~C) and MCF10A breast cells (D~F) treated with Cy3-trastuzumab/fFcBP-Pf_Fn complexes. Trastuzumab and FcBP-Pf_Fn, which were labeled with Cy3 (Cy3-trastuzumab) and fluorescein (fFcBP-Pf_Fn), respectively, selectively targeted SKBR3 over MCF10A.