• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.344-352
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• 2010

Objectives: The purpose of this study was to determine the setting time, compressive strength, solubility, and pH of mineral trioxide aggregate (MTA) mixed with glass ionomer cement (GIC) and to compare these properties with those of MTA, GIC, IRM, and SuperEBA. Materials and Methods: Setting time, compressive strength, and solubility were determined according to the ISO 9917 or 6876 method. The pH of the test materials was determined using a pH meter with specified electrode for solid specimen. Results: The setting time of MTA mixed with GIC was significantly shorter than that of MTA. Compressive strength of MTA mixed with GIC was significantly lower than that of other materials at all time points for 7 days. Solubility of 1 : 1 and 2 : 1 specimen from MTA mixed with GIC was significantly higher than that of other materials. Solubility of 1 : 2 specimen was similar to that of MTA. The pH of MTA mixed with GIC was 2-4 immediately after mixing and increased to 5-7 after 1 day. Conclusions: The setting time of MTA mixed with GIC was improved compared with MTA. However, other properties such as compressive strength and pH proved to be inferior to those of MTA. To be clinically feasible, further investigation is necessary to find the proper mixing ratio in order to improve the drawbacks of MTA without impairing the pre-existing advantages and to assess the biocompatibility.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.445-454
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• 2019

Layered double hydroxides (LDHs) nanoparticles have emerged as novel nanomaterials for bio-imaging applications due to its unique layered structure, physicochemical properties, and good biocompatibility. Bio-imaging is one of the most important fields for medical applications in clinical diagnostics and therapeutics of various diseases. Enhanced diagnostic techniques are needed to realize new paradigm for next-generation personalized medicine through nanoscale materials. When nanotechnology is introduced into bio-imaging system, nanoparticle probes can endow imaging techniques with enhanced ability to obtain information about biological system at the molecular level. In this review, we summarize structural features of LDH nanoparticles with current issues of bio-imaging system. LDH nanoparticle probes are also discussed through in vitro as well as in vivo studies in various bio-imaging techniques including fluorescence imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), and computed X-ray tomography (CT), which will have the potential in the development of the advanced nanoparticles with high sensitivity and selectivity.

• Journal of the Korean Chemical Society
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• v.62 no.1
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• pp.24-29
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• 2018

Despite the great potential for the versatile applications in food industry and medical area, chitosan as a biocompatible cationic polysaccharide has suffered from the limited solubility under physiological condition. Herein, we demonstrated the electrostatic formation of chitosan-based polyplex particles, counterbalanced by polyacrylate as an anionic polyelectrolyte. The resulting polyplex exhibited pH- and composition-dependent changes in their surface charges as measured by zeta potential, which can be employed to provide the interparticle repulsive forces for enhanced colloidal stability in homogeneous solution. Subsequently, amide coupling between the acrylates and glucosamine residues of chitosan inside the polyplex further generated the hydrogel particles, which showed the temperature-sensitive swelling property. This aspect can be attributed to the partial formation of acryl amide residues, which have been generally known to possess the lower critical solution temperature (LCST).

• Journal of Life Science
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• v.26 no.5
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• pp.545-554
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• 2016

Hyaluronic acid (HA) is an important macromolecule in medical and pharmaceutical fields. HA is a natural and linear polymer composed of repeating disaccharide units of β-1, 3-N-acetyl glucosamine and β-1, 4-glucuronic acid. This work aimed to confirm the structural characteristics and anti-inflammatory activities of HA and its chemically sulfated-HA. HA was produced from a fed-batch fermentation process using Streptococcus dysgalactiae in a 5 l bioreactor. HA was isolated water-soluble form (HA-WS) and water-insoluble form (HA-WI) from culture medium, and was obtained chemically sulfated-derivative (S-HA) that resulted in a 90% yield from HA-WI. The structural features of the sulfated- HA (S-HA) were investigated by FT-IR and ¹H-NMR spectroscopy. The FT-IR and NMR patterns revealed the similarity in both the FTIR spectrum as well as NMR spectrum of both reference standard and purified HA from S. dysgalactiae. The anti-inflammatory activities of HA and S-HA were examined on LPS-induced RAW 264.7 cells. S-HA was significantly inhibited production of pro-inflammatory mediators such as nitric oxide (NO) and PGE₂ and the gene levels of iNOS and COX-2, which are responsible for the production of NO and PGE₂, respectively. Furthermore, S-HA also suppressed the overproduction of pro-inflammatory cytokine TNF-α (<80 pg/ml) and IL-6 (<100 pg/ml) compared to that of HA-WI. The present study clearly demonstrates that HA-S exhibits anti-inflammatory activities in RAW 264.7 macrophage cells.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.935-939
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• 2018

3D Printing technology is developing in various prototypes for medical treatment, food, fashion as well as machinery and equipment parts production. 3D printing technology is also able to fully be utilized to other industries in terms of developing its technology which has been reported in many field of areas. 3D printing technology is expected to be used in various applications related to $4^{th}$ industrial revolution such as finished products and parts even it is still carried out in the prototype model. In this study, we have investigated and developed conductive resin for 3d printing application based on reduced graphene oxide(rGO)/Polypyrrole(Ppy) composite and polycaprolactone(PCL) as a biodegradable polymer. The electrical properties and surface morphology of the conductive PCL resin based on therGO/Ppy composite were analyzed by 4point-probe and scanning electron microscope(SEM). The conductive PCL resin based on rGO/Ppy composite is expected to be applicable not only 3D printing, but also electronic materials in other industrial fields.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.1
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• pp.88-98
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• 2016

The pharmacological effects of ginseng berry have been known to improve psychological function, immune activities, cardiovascular conditions, and certain cancers. It is also known that fermentation improves the bioavailability of human beneficial natural materials. Accordingly, we investigated the optimal fermentation conditions of ginseng berry extract with strain isolated from conventional foods. We also analyzed the fermentation product and its antioxidant activity. The bacterium isolated from fermented kimchi was identified as Lactobacillus sp. strain KYH. To optimize the process, fermentation was performed in a 5 L fermenter containing 3 L of ginseng berry extract at 200 rpm for 72 hr. Under optimized conditions, batch and fed-batch fermentations were performed. After fermentation, organic acids, amino acids, sugars, ginsenosides, and antioxidant activity were evaluated. The optimum fermentation conditions were determined as pH 7.0 and a temperature of $30^{\circ}C$, respectively. After fermentation, the amounts and compositions of organic acids, amino acids, sugars, ginsenosides, and antioxidant activity were altered. In comparing the distribution of ginsenosides with that before fermentation, the ginsenoside Re was a major product. However, amounts of ginsenosides Rb1, Rc, and Rd were reduced, whereas amounts of ginsenosides Rh1 and Rh2 increased. Total phenol content increased to 43.8%, whereas flavonoid content decreased to 19.8%. The DPPH radical scavenging activity and total antioxidant activity increased to 27.2 and 19.4%, respectively.

• The Korean Journal of Nuclear Medicine
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• v.32 no.6
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• pp.516-524
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• 1998

Purpose: Radiolabeled CEA79.4 antibody has a possibility to be used in radioimmunoscintigraphy or radioimmunotherapy of cancer. We investigated the in vitro properties and biodistribution of CEA79.4 antibody labeled with Re-188 or Tc-99m. Materials and Methods: CEA79.4 was reduced by 2-mercaptoethanol to produce-SH residue, and was labeled with Re-188 or Tc-99m. For direct labeling of Tc-99m, methylene-diphosphonate was used as transchelating agent. CEA79.4 in 50 mM Acetate Buffered Saline (ABS, pH 5.3) was labeled with Re-188, using stannous tartrate as reducing agent. In order to measure immunoreactivity and the affinity constant of radiolabeled antibody, cell binding assay and Scatchard analysis using human colon cancer cells SNU-C4, were performed. Biodistribution study of labeled CEA79.4 was carried out at 1, 14 and 24 hr in ICR mice. Results: Labeling efficiencies of Tc-99m and Re-188 labeled antibodies were $92.4{\pm}5.9%$ and $84.7{\pm}4.6%$, respectively, In vitro stability of Tc-99m-CEA79.4 in human serum was higher than Re-188-CEA79.4. Immunoreactivity and affinity constant of Tc-99m-CEA79.4 were 59.2% and $6.59{\times}10^9\;M^{-1}$, respectively, while those of Re-188-CEA79.4 were 41.6% and $4.2{\times}10^9\;M^{-1}$, respectively. After 24 hr of administrations of Re-188 and Tc-99m labeled antibody, the remaining antibodies in blood were 6.32 and 9.35% ID/g respectively. The biodistribution of each labeled antibody in other organs was similar because they did not accumulate in non-targeted organs. Conclusion: In vitro properties and biodistribution of Re-188-CEA79.4 were similar to those of Tc-99m-CEA79.4. It appears that Re-188-CEA79.4 can be used as a suitable agent for radioimmunotheraphy.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.73-82
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• 2009

Injectable calcium phosphate cement (CPC) has been used as bone substitute successfully due to good biocompatibility and osteoconductivity. One of the important mechanical characteristics of CPC is flowablility, which can be evaluated by measuring rheological parameters. However, there have been few studies that measured rheological properties of CPC. The purpose of this study was to evaluate the effects of temperature and concentrations of 2 kinds of setting solutions, hydroxyprophyl methylcellulose (HPMC) and polyacrylic acid (PAA), on rheological properties of CPC. The CPC used was dicalcium phosphate dihydrate (DCPD). Rheological properties of CPC paste were measured using rheometer. The effect of concentrations of each solution (2% and 1% HPMC and 35% and 17.5% PAA) was evaluated. The effect of temperature ($25^{\circ}C$ and $37^{\circ}C$) on the rheological properties of CPC was also investigated. The statistical analysis was carried out with Mann-whitney test with Bonferronis collection. CPC with both setting solutions showed shear thinning behavior. Higher concentrations of setting solution (2% HPMC and 35% PAA) produced significantly higher viscosity than lower concentrations of setting solution (1% HPMC and 17.5% PAA). CPC with HPMC showed significantly higher viscosity at $37^{\circ}C$ that at $25^{\circ}C$. CPC with PAA showed lower viscosity at $37^{\circ}C$ than at $25^{\circ}C$, although the difference was not statistically significant. The results showed that CPC with HPMC or PAA solutions are pseudoplastic and the concentrations of setting solutions and temperature may have an effect on the rheological properties of CPC paste. These results showed that the flowability of injectable CPC could be improved by use of increasing frequency of oscillation. In clinical practice, the use of ultrasonic vibration would be helpful in application of injectable CPC. CPC with HPMC could be more easily applicated at $25^{\circ}C$ than $37^{\circ}C$. The use of lower concentrations of HPMC and PAA solution would be beneficial in terms of flowability.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.156-163
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• 2017

People with class I intellectual disability need lifelong assistance and protection from their surroundings due to impaired adaptive functioning. They have poor oral health and show higher prevalence of dental caries, periapical inflammation and tooth loss that require proper prosthetic restoration. Because removable prostheses for intellectually disabled patients often lack stability, retention, and maintenance, fixed prostheses are essential and the only available option is dental implants. In this case, a 45 year-old male patient with class I intellectual disability had poor oral hygiene with most of his teeth missing and visited the clinic to recover his masticatory function. Due to such systemic conditions, the definitive restoration of choice was the implant-supported fixed dental prosthesis made of biocompatible and highly strong monolithic zirconia. In consequence of the treatment process, the patient was able to improve his oral environment aesthetically and functionally.

• KSBB Journal
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• v.22 no.1
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• pp.7-15
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• 2007

Extensive research was carried out for inhibition of melanin formation as development of whitening cosmetic ingredients. But degradation of melanin itself was not intensively pursued as development of cosmetics. In this study, novel melanin degradation enzyme was developed and characterized. Also this enzyme production process was optimized and formulation was tried using micro encapsulation technique.