Papers by Author: Sang Hoon Rhee

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Authors: Seung Hoon Um, Sang Hoon Rhee
Abstract: Effect of oxide layer formed on commercially pure titanium by heat-treatment on adhesion of serum proteins and differentiation activity of osteoblasts. Commercially pure titanium disks were polished and then heat-treated at 700°C for 30 minutes. Titanium oxide layer (rutile phase) was observed to form on the titanium disk surface after heat-treatment. The contact angle of a water droplet on the heat-treated titanium disk was about 14o while that of non-heat treated one was about 68o. The amount of adsorbed total serum protein on heat-treated titanium disk was four times higher than that on non-heat treated one. ALP activity of primary cultured mouse calvarial osteoblasts on heat-treated titanium disk was also higher than that on non-heat treated one with statistical significance of p < 0.05. It implies that the serum proteins preferentially adsorbed on titanium oxide layer formed on commercially pure titanium and it is likely to enhance the differentiation activity of primary cultured mouse cultured osteoblasts.
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Authors: Sang Hoon Rhee, Il Yong Chung, Yong Keun Lee, Bum Soon Lim, Yang Jo Seol
Abstract: Non-woven silica fabric was made by electro-spinning method for the potential application as a bone grafting material. The silica gel, the source material for electro-spinning, was prepared by the hydrolysis of tetraethyl orthosilicate in the presence of calcium salt, water, hydrochloric acid and ethanol. It was transferred to a syringe, which was connected to the high voltage supply generating a high electric field between the spinneret and the ground collecting drum. The silica fibers containing calcium were spun under the electric field of 2 KV/cm. Their diameters were in the range from about 0.3 μm to 8 μm. It was heat-treated at 300 oC for 3 hours. After soaking in the SBF for 1 week, low crystalline apatite crystals were observed to occur on their surfaces. From the results, it can be concluded that the non-woven silica fabric containing calcium made by electro-spinning method and then heat-treated has a bioactivity. It means it has a potential to be used as a bone grafting material because of its apatite-forming ability, high surface area to volume ratio and high porosity.
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Authors: Hanna Yoon, Yong Keun Lee, Bum Soon Lim, Sang Hoon Rhee
Abstract: Non-woven silica fabric was made by electro-spinning method for the application as a bone grafting material. The silica gel, the source material for electro-spinning, was prepared by the hydrolysis of tetraethyl orthosilicate in the presence of water, hydrochloric acid and ethanol. It was transferred to a syringe (spinneret), which was connected to the high voltage supply generating a high electric field between the spinneret and the ground collecting drum. The silica fibers were spun under the electric field of 2 KV/cm. Their diameters were in the range from about 100 nm to 5 µm. After soaking in the SBF for 4 week, low crystalline apatite crystals were observed to occur partly on their surfaces. From the results, it can be concluded that the non-woven silica fabric made by electro-spinning method has the apatite forming ability in the SBF and it means it has a potential to be used as a bone grafting material because of its apatite-forming ability, high surface area to volume ratio and high porosity.
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Authors: Hye Young Shin, Sang Hee Shin, Sang Hoon Rhee
Abstract: The low crystalline hydroxyl carbonate apatite forming capacity of a poly (70lactic-co-30glycolic acid)/15CaO-85SiO2 composite, which had a dual pore structure, was newly examined in simulated body fluid. The bioactive 15CaO-85SiO2 particles were synthesized by a sol-gel method using tetraethyl orthosilicate (TEOS) and calcium nitrate tetrahydrate under acidic condition followed by the heat treatment at 600°C for 3h. The poly (70lactic-co-30glycolic acid)/15CaO-85SiO2 composite was then prepared by a solvent casting using dimethylformide as a solvent. The composite was loaded into a high pressure chamber and then carbon dioxide gas was introduced achieving a final pressure of 20 MPa. After 3 days, carbon dioxide gas was released quickly and resultantly the dual pore structure was obtained. The samples were observed by FE-SEM and its bioactivity was tested in simulated body fluid.
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Authors: Sang Hoon Rhee, Ho Nam Park, Yang Jo Seol, Chong Pyong Chung, Sang Hyuk Han
Abstract: Effect of heat-treatment temperature on the osteoconductivity of the apatite derived from bovine trabecular bone was investigated. Three different heat-treatment temperatures (600, 800 and 1000 oC) were adopted in the experiment and their effects on the physical properties of apatite granules, which could affect on the osteoconductivity, were evaluated. The content of carbonate ions in the apatite structure was assessed by FT-IR and its crystallinity was evaluated by X-ray diffractometry. The microstructure was assessed by field emission electron microscopy. Apatite granules heat-treated at 600 oC and 1000 oC were implanted into the calvaria of New Zealand White rabbit for 4 weeks, respectively, and the undecalcified ground histologic specimens stained with multiple staining method was observed. As increasing the heat-treatment temperature, the crystal size and crystallinity of the apatite increased while the content of carbonate ions decreased. The apatite granules heat-treated at 600 oC showed much better osteoconductivity comparing to that heat-treated at 1000 oC. The results were explained in terms of the physical properties of apatite which could affect to the osteoconductivity.
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