• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.453-466
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• 2020

As the demand for eco-friendly energy increases to overcome the energy shortage and environmental pollution crisis, hydrogen economy has been proposed as a potential solution. Accordingly, an economical and efficient hydrogen production is considered to be an essential industrial process. Research on applying hydrogen separation membranes for H₂/CO₂ separation to the production of highly concentrated hydrogen by purifying H₂ and capturing CO₂ simultaneously from synthetic gas produced by gasification is in progress nowadays. In high temperature environments, the membrane separation process using glassy polymeric membrane with H₂ selectivity has the potential for CO₂ capture performance, and is an energy and cost effective system since polybenzimicazole (PBI)-based separators show excellent chemical and mechanical stability under high-temperature operation conditions. Thus, the development of high-performance PBI hydrogen separators has been rapidly progressing in recent years. This overview focuses on the recent developments of PBI-based membranes including structure modified, cross-linked, blended and carbonized membranes for applications to the industrial hydrogen separation process.

• Polymer(Korea)
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• v.32 no.1
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• pp.26-30
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• 2008

This study was designed to investigate the effect of hybridization of synthetic/natural materials for annulus fibrosus (AF) tissue regeneration in vitro and in vivo. The synthetic/natural hybrid scaffolds were prepared using PLGA (poly (lactic-co-glycolic) acid), SIS (small intestinal submucosa) and DBP (demineralized bone particles). PLGA, PLGA/SIS(20%), PLGA/DBP(20%) and PLGA/SIS (10%)/DBP (10%) scaffold were manufactured by solvent casting/salt leaching method. Compressive strength was measured. Rabbit AF cells were isolated, cultured and seeded into experimental groups. Hydroxyproline production and DNA quantity of AP cells on each scaffold was measured at 2, 4 and 6 weeks after in vitro culture. Cell-scaffold composites were implanted subcutaneously into athymic mice. After 1,4 and 6 weeks postoperatively, specimens were taken and H&E, Safranin-O and type I collagen staining were carried out concerning formation of cartilagenous tissue. In vitro PLGA/SIS scaffold was evaluated for total collagen content (bydroryproline/DNA content) and PLGA scaffold was evaluated for compressive strength.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.135-141
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• 2001

Of hot-water extracts prepared from 10 herbal components of Sip-Jeon-Dae-Bo-Tang, Atractylodes lancea DC. (ALR) and Panax ginseng C.A. Meyer (PG) showed the most potent bone marrow cell proliferation activity through intestinal immune system whereas other extracts did not have the activity except for Astragalus membranacues Bunge (ASR) and Angelica acutiloba Kitagawa (AR) having low activity. Especially, ALR had the potent activity irrespective of classes of ALR, a place of production and the condition of breeding. In addition, we found that hot-water extract from Atractylodes lancea DC rhizomes (ALR-0) contributed mainly to Peyer's patch cells mediated-hematopoietic response of Sip-Jeon-Dae-Bo-Tang. ALR-0 was further fractionated into MeOH-soluble fraction (ALR-1), MeOH-insoluble and EtOH-soluble fraction (ALR-2), and the crude polysaccharide fraction (ALR-3). Among these fractions, only ALR-3 showed potent stimulating activity for proliferation of bone marrow cells mediated by Peyer's patch cells, dose-dependently. In treatments of ALR-3 with $NaIO_4,\;NaClO_2$ and pronase, all significantly reduced the intestinal immune system modulating activity of ALR-3, and the activity of ALR-3 was much affected by $NaIO_4$ oxidation particularly. These results reveal that macromolecules, such as polysaccharide, rather than low-molecular-weight substances, are the potent intestinal immune system modulating compound of ALR.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.97-104
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• 2018

In recent years, more than 5,000 tons of sargassum honeri have been infested in the southern coast and the coast of Jeju Island, causing serious damage to the farms and fisheries, and environmental problems. The alginate contained in the sargassum honeri is a natural polymeric substance mainly used for medicines and foods. However, since there is no way to utilize it in large quantities, a study was carried out to utilize bio polymer obtained from sargassum honeri in producing polymer mortar for repairing deteriorated infrastructures. From the tests of setting time, it was found that the L0BP12 mixture containing 12% of bio polymer increased the setting time by 20% as compared with the L12BP0 mixture using only synthetic polymer. From the tests of water absorbtion, the LOBP12 combination decreased by 0.36% compared to Plain-URHC using ultra rapid hardening cement. This indicated that the watertightness of the mortar was increased by the incorporation of the bio polymer. In the compressive and flexural strength tests, the strength decreased as the amount of bio polymer increased. The incorporation rate of the maximum bio polymer satisfying the KS F 4042 standard was determined to be 12%. In addition, the bond strength of the mortar produced with biopolymer was higher than that of Plain-URHC specimens, and it was confirmed that incorporation of bio polymer improves bond strength of mortar.

• Polymer(Korea)
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• v.28 no.5
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• pp.382-390
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• 2004

One of the significant natural bioactive materials is demineralized bone particle (DBP) whose has a powerful induce. of new bone growth. In this study, we developed the DBP loaded poly-lactide (PLA) and poly(L-lactide-co-glycolide) (PLGA) scaffolds for the possibility of the application of the tissue engineered bone. PLA/DBP and PLGA/DBP scaffolds were prepared by solvent casting/salt leaching method and were characterized by porosimeter, scanning electron microscopy. BMSCs were stimulated by osteogenic medium and characterized by histological stained Wright-Giemsa, Alizarin red, von Kossa, and alkaline phosphate activity (ALP). DBP impregnated scaffolds with BMSCs were implanted into the back of athymic nude mouse to observe the effect of DBP on the osteoinduction compared with control scaffolds. It can be observed that the porosity was above $90.2\%$ and the pore size was above 69.1$\mu$m. BMSCs could be differentiated into osteoprogenitor cells as result of wright-giemsa, alizarin red, von Kossa and ALP staining. In in vivo study, we could observed calcification region in PLA/DBP and PLGA/DBP groups, but calcification did not occur almost in control scaffolds. From these results, it seems that DBP as well as BMSCs play an important role for bone induction in PLA/DBP and PLGA/DBP scaffolds.

• Polymer(Korea)
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• v.35 no.4
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• pp.289-295
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• 2011

Biomaterials for retinal tissue engineering must demonstrate several critical features for potential utility, including mechanical integrity, biocompatibility, and slow biodegradation. Silk film biomaterials were designed and characterized to meet these functional requirements. We prepared natural/synthetic hybrid silk/PLGA films using 0, 10, 20, 40, and 80 wt% of silk by a solvent evaporation method. MIT assay was used to confirm the number of cells attached on film at 1, 2, and 3 days, respectively. The morphology of cellular adhesion on films was also confirmed by scanning electron microscope (SEM). RT-PCR was conducted to confrrm mRNA expression of retinal pigment epithelitun (RPE) using RPE65 as a RPEs marker and the expression of cytokeratin were determined by immunofluorescence staining. We confirmed that the silk/PLGA film of 20~40 wt% silk was superior for the adhesion and proliferation of RPEs.

• Polymer(Korea)
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• v.35 no.6
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• pp.499-504
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• 2011

Articular cartilage has an intrinsic difficulty in recovering damages, which requires its tissue engineering treatment. Demineralized bone particle (DBP) contains various bioactive molecules. It is widely used biomaterials in the field of tissue engineering. We developed the synthetic/natural hybrid scaffolds with poly(lactide-co-glycolide) (PLGA) and solution of DBP. The chondrocytes were seeded on the PLGA-DBP scaffolds and MTT assay, morphological observation, biological assay for collagen, sGAG, and RT-PCR were performed to analyze the effect of the DBP on cell viability and extracellular matrix secretion. In SEM observation, we observed that PLGA-DBP scaffolds had uniform porosity. As MTT assay showed scaffolds containing DB solution had higher cell viability then only PLGA scaffolds. The PLGA-DBP scaffolds had better ECM production than PLGA scaffold. It was proven by the higher specific mRNA expression in the PLGA-DBP scaffold than that in PLGA scaffold. These results indicated that PLGA-DBP scaffolds might serve as potential cell delivery vehicles and structural bases for in vitro tissue engineered articular cartilage.

• Polymer(Korea)
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• v.33 no.2
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• pp.104-110
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• 2009

Demineralized boneparticle (DBP) has been widely used as and a powerful promoter of new bone growth. In this study, DBP sponges were chemically crosslinked and characterized for the potential application of tissue engineered scaffolds. The DBP sponges prepared by crosslinking with EDC. 0.1, 0.2 or 0.3% pepsin was applied to DBP dissolved in 3% (v/v) acetic acid aqueous solution for 48 hrs. The prepared sponges were crosslinked by 1, 5, 10, 50 or 100 mM of EDC solution concentration and then were lyophilized. The DBP sponges were characterized by SEM, FT-IR and DSC and analyzed in terms of their porosity and water absorption ability. The cellular viability and proliferation were assayed by MTT assay. Our investigation revealed that 0.2$\sim$0.3% of pepsin and 50$\sim$100 mM of EDC produced DBP sponges with good physical characteristics. In conclusion, DBP sponge prepared under these conditions is potentially useful for the applications of tissue construction.

• Polymer(Korea)
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• v.32 no.5
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• pp.403-408
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• 2008

Keratin is the major structural fibrous protein providing outer covering such as wool, hair, and nail. Keratin is useful as natural protein. We developed the keratin loaded poly(L-lactide-co-glycolide) (PLGA) scaffolds (keratin/PLGA) for the possibility of the application of the tissue engineering using bone marrow mesenchymal (BMSCs). Keratin/PLGA (contents 0%, 10%, 20% and 50% of PLGA weight) scaffolds were prepared by solvent casting/salt leaching method. We characterized porosity, wettability, and water uptake ability, DSC of keratin/PLGA scaffold. We seeded BMSCs isolated from the femurs of rat into the inner core of the hybrid scaffold. Celluar viability were assayed by 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl-tetrazolium bromide (MTT) test. We confirmed that keratin/PLGA scaffold is hydrophilic by wettability, and water uptake ability measurement results. In MTT assay results, cell viability in scaffolds impregnated 10 and 20 wt% of keratin were higher than other scaffolds. In conclusion, we suggest that keratin/PLGA scaffold may be useful to tissue engineering using BMSCs.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.467-472
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• 2011

This study investigated illite/polypropylene (PP) composite filament formation via melt-spinning and evaluated their physical properties to prepare functional fibers using natural materials. When composite filaments were formed, the composite filaments exhibited smaller fiber diameters compared to that of neat PP filament because of the lubricant effect of illite induced by its layered structure. Moreover, fluorination effect increased interfacial affinity and dispersion in the polymer, resulting in smaller diameter of fluorinated illite/PP composite filament, which was 2/3 of the neat PP filament diameter. Addition of raw and fluorinated illite improved thermal stability of illite/PP composite filament. Raw illite/PP composite filament cannot be used for a practical application, because it broke during drawing process, whereas the fluorinated illite/PP composite filament can be used for a practical application, because it exhibited similar tensile strength of the neat PP filament and 50% increased modulus. Even with improved illite/PP interfacial affinity and illite dispersion in the polymer, illite/PP composite filament formed microcomposite, because non-expandable illite had strongly bound layers, resulting in only a little illite exfoliation and PP intercalation into illite.