• Title/Summary/Keyword: biomaterials

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Electrochemical Behaviors of Binary Ti-Zr Alloys

  • Oh, M.Y.;Kim, W.G.;Choe, H.C.;Ko, Y.M.
    • Corrosion Science and Technology
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    • v.8 no.2
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    • pp.89-92
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    • 2009
  • Pure Ti as well as Ti-6Al-4V alloy exhibit excellent properties for dental implant applications. However, for a better biocompatibility it seems important to avoid in the composition the presence of V due to the toxic effects of V ion release. Thus Al and V free and composed of non-toxic element such as Nb, Zr alloys as biomaterials have been developed. Especially, Zr contains to same family in periodic table as Ti. The addition of Zr to Ti alloy has an excellent mechanical properties, good corrosion resistance, and biocompatibility. In this study, the electrochemical characteristics of Ti-Zr alloys for biomaterials have been investigated using by electrochemical methods. Methods: Ti-Zr(10, 20, 30 and 40 wt%) alloys were prepared by arc melting and homogenized for 24 hr at $1000^{\circ}C$ in argon atmosphere. Phase constitutions and microstructure of the specimens were characterized by XRD, OM and SEM. The corrosion properties of the specimens were examined through potentiodynamic test (potential range of -1500 ~ 2000 mV), potentiostatic test (const. potential of 300 mV) in artificial saliva solution by potentiostat (EG&G Co, PARSTAT 2273. USA).

Molecular Structure of Sorghum and Waxy Sorghum Starches

  • Han, Young-Joo;Park, Jong-Tae;Le, Quang Tri;Shim, Jae-Hoon;Nguyen, Van Dao;Kim, Yong-Ro;Park, Kwan-Hwa
    • Food Science and Biotechnology
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    • v.17 no.1
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    • pp.176-179
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    • 2008
  • Amylose contents and amylopectin chain architecture of sorghmn and waxy sorghum starches were determined and compared with those of other common cereal and tuber starches. Also, in vitro digestibility of sorghum starch was estimated using a novel methodology. The absolute amylose content of sorghum starch was similar to that of com and wheat starches. The side chain length distribution patterns for sorghum and waxy sorghum amylopectin were very similar to those of com and waxy com, respectively. The $k_{cat}/K_m$ values for sorghum and potato amylopectin did not show a significant difference. The kinetic parameters could be used as novel indicators for starch digestibility.

Mixed matrix membranes of poly(vinyl alcohol) loaded with phosphomolybdic heteropolyacid for the pervaporation separation of water-isopropanol mixtures (Water-IsopropanoI 혼합물의 투과증발 분리를 위한 poly(vinyl alcohol)-phosphomoIybdic heteropolyacid 혼합막)

  • Teli, Shivanand;Choi, Hyoung-Woo;Moon, Jung-Me;Park, Ji-Hye;Hong, Sung-Pyo;Tak, Tae-Moon
    • Proceedings of the Membrane Society of Korea Conference
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    • 2008.05a
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    • pp.51-57
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    • 2008
  • Mixed matrix membranes of poly(vinyl alcohol) (PVA), loaded with phosphomolybdic heteropolyacid (HPA) and crosslinked with glutaraldehyde have been prepared by the solution casting technique. Pervaporation (PV) experiments have been performed at $30^{\circ}C$ to separate water-isopropanol feed mixtures containing 10 to 40 wt.% of water. The membranes were characterized by DSC and DMTA to understand their thermal behavior and mechanical strength properties. At high content (i.e. 7 wt.% with respect to weight of PVA) of HPA, the mixed matrix membranes could extract water efficiently on the permeate side with a selectivity of 90,000 and a flux of 0.032 $kg/m^2h$ for 10 wt.% of water containing feed mixture (the lowest feed composition of water studied). Flux of the mixed matrix membranes decreased with increasing concentrations of HPA.

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Effect of Lyoprotectant on the Solubility and Structure of Silk Sericin

  • Kim, Moo-Kon;Kwak, Hyo-Won;Lee, Jeong-Yun;Yun, Hae-Sung;Kim, Min-Hwa;Lee, Ki-Hoon
    • International Journal of Industrial Entomology
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    • v.25 no.1
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    • pp.133-137
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    • 2012
  • To increase the solubility of lyophilized sericin, we added three types of lyoprotectant: sucrose, trehalose and dextran. The addition of lyoprotectant increased the solubility of lyophilized sericin especially when 1.0% of sucrose, 1.0% and 1.5% trehalose are added. The secondary structure of lyophilized sericin showed that the content of ${\beta}$-sheet or aggregated structure reduced in the presence of lyoprotectant. The morphology of lyophilized was also affected by the addition of lyoprotectant. Whereas flake structure was obtained in the case of pure sericin, a scattered and relatively small flake structure was formed in the presence of lyoprotectant. These finding shows that the presence of lyoprotectant prevents aggregation of sericin molecules and increases the solubility of lyophilized sericin.

Preparation and Drawing Property of Poly(vinyl alcohol) Film (폴리비닐알코올 필름의 제조 및 연신 특성)

  • Kim, Hun Min;Lee, Jungeon;Park, Jae Min;Park, Jae Hyeung;Choi, Jin Hyun;Yeum, Jeong Hyun
    • Textile Coloration and Finishing
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    • v.33 no.3
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    • pp.147-152
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    • 2021
  • Bulk polymerization was used to produce poly(vinyl acetate) with different molecular weights, which were then saponified to prepare poly(vinyl alcohol) (PVA) with different molecular weights. With Pn of 2,060 and 3,240, the optimum film formation concentrations of PVA were found 7.5wt.% and 6.5wt.%, respectively. The drawing characteristics of the PVA film prepared at the optimum film formation concentrations were experimented, as well as the thermal characteristics of the PVA film based on the drawing ratio were observed. When the drawing velocity was fixed, it was found that the drawing ratios of all samples decreased as the heat band gap increased, and the melting temperature of the PVA film slightly increased as the drawing ratio increased regardless of the Pn of PVA.

Comparative analysis of yeast cell viability at exponential and stationary growth phases

  • An, Yejin;Jo, Nayoon;Kim, Hyeji;Nam, Dahye;Son, Woorim;Park, Jinkyu
    • Analytical Science and Technology
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    • v.35 no.4
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    • pp.181-188
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    • 2022
  • This paper describes a comparative analysis of yeast cell viability at exponential and stationary growth phases using multiple conventional techniques and statistical tools. Overall, cellular responses to various viability assays were asynchronous. Results of optical density measurement and direct cell counting were asynchronous both at exponential and stationary phases. Proliferative capacity measurement using SP-SDS indicated that cells at the end of the stationary phase were proliferative as much as exponentially growing cells. Metabolic activity assays using two different dyes concluded that the inside of cells at stationary phase is slightly less reducing compared to that of exponentially growing cells, implying that the metabolic activity imperceptibly declined as cells were aged. These results will be helpful to understand the details of yeast cell viability at exponential and stationary growth phases.

Development and Application of a Novel Mammalian Cell Culture System for the Biocompatibility and Toxicity of Polymer Films and Metal Plate Biomaterials (고분자필름과 금속막 의료소재에 대한 생체적합성 및 독성 평가를 위한 새로운 세포배양시스템의 개발 및 적용)

  • Kwak, Moon Hwa;Yun, Woo Bin;Kim, Ji Eun;Sung, Ji Eun;Lee, Hyun Ah;Seo, Eun Ji;Nam, Gug Il;Jung, Young Jin;Hwang, Dae Youn
    • Journal of Life Science
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    • v.26 no.6
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    • pp.633-639
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    • 2016
  • Biomaterials including polymer, metal, ceramic, and composite have been widely applied for medical uses as medical fibers, artificial blood vessels, artificial joints, implants, soft tissue, and plastic surgery materials owing to their physicochemical properties. However, the biocompatibility and toxicity for film- and plate-form biomaterials is difficult to measure in mammalian cells because there is no appropriate incubation system. To solve these problems, we developed a novel mammalian cell culture system consisting of a silicone ring, top panel, and bottom panel and we applied two polymer films (PF) and one metal plate (MP). This system was based on the principal of sandwiching a test sample between the top panel and the bottom panel. Following the assembly of the culture system, SK-MEL-2 cells were seeded onto Styela Clava Tunic (SCT)-PF, NaHCO3-added SCT (SCTN)-PF, and magnesium MP (MMP) and incubated at 37℃ for 24 hr and 48 hr. An MTT assay revealed that cell viability was maintained at a normal level in the SCT-PF culture group at 24 or 48 hr, although it rapidly decreased in the SCTN-PF culture group at 48 hr. Furthermore, the cell viability in the MMP culture group was very similar to that of the control group after incubation for 24 hr and 48 hr. Together, these results suggest the sandwich-type mammalian culture system developed here has the potential for the evaluation of the biocompatibility and toxicity of cells against PF- and MP-form biomaterials.

Inhibition of endoplasmic reticulum stress in high-fat-diet-induced obese C57BL/6 mice: Efficacy of a novel extract from mulberry (Morus alba) leaves fermented with Cordyceps militaris

  • Lee, Mi Rim;Bae, Su Ji;Kim, Ji Eun;Song, Bo Ram;Choi, Jun Young;Park, Jin Ju;Park, Ji Won;Kang, Mi Ju;Choi, Hyeon Jun;Choi, Young Whan;Kim, Kyung Mi;Hwang, Dae Youn
    • Laboraroty Animal Research
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    • v.34 no.4
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    • pp.288-294
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    • 2018
  • A few clues about correlation between endoplasmic reticulum (ER) stress and mulberry (Morus alba) leaves were investigated in only the experimental autoimmune myocarditis and streptozotocin-induced diabetes. To investigate whether a novel extract of mulberry leaves fermented with Cordyceps militaris (EMfC) could suppress ER in fatty liver, alterations in the key parameters for ER stress response were measured in high fat diet (HFD)-induced obese C57L/6 mice treated with EMfC for 12 weeks. The area of adipocytes in the liver section were significantly decreased in the HFD+EMfC treated group as compared to the HFD+Vehicle treated group, while their level was higher in HFD+Vehicle treated group than No treated group. The level of the eukaryotic initiation factor 2 alpha ($eIF2{\alpha}$) and inositol-requiring enzyme 1 beta ($IRE1{\alpha}$) phosphorylation and CCAAT-enhancer-binding protein homologous protein (CHOP) expression were remarkably enhanced in the HFD+Vehicle treated group. However, their levels were restored in the HFD+EMfC treated group, although some differences were detected in the decrease rate. Similar recovery was observed on the ER stress-induced apoptosis. The level of Caspase-3, Bcl-2 and Bax were decreased in the HFD+EMfC and HFD+orlistat (OT) treated group compared to the HFD+Vehicle treated group. The results of the present study therefore provide first evidence that EMfC with the anti-obesity effects can be suppressed ER stress and ER stress-induced apoptosis in the hepatic steatosis of HFD-induced obesity model.

Preparation and Drug Release Properties of Naproxen Imprinted Biodegradable Polymers Based Multi-Layer Biomaterials (나프록센이 각인된 생분해성 고분자 기반 다층 바이오소재의 제조 및 약물 방출 특성)

  • Eun-Bi Cho;Han-Seong Kim;Min‑Jin Hwang;Soon-Do Yoon
    • Applied Chemistry for Engineering
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    • v.34 no.2
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    • pp.161-169
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    • 2023
  • In this study, we prepared naproxen (NP) imprinted biodegradable polymer based multi-layer biomaterials using allbanggae starch (ABS), polyvinyl alcohol (PVA), and alginic acid (SA), and investigated their physicochemical properties and the controlled drug release effects. In addition, the prepared multi-layer biomaterials were characterized by FE-SEM and FT-IR. In order to confirm the controlled drug release effect for the transdermal drug delivery system (TDDS), the NP release properties of NP imprinted multi-layer biomaterials were investigated using various pH buffer solutions and artificial skin at 36.5 ℃. The results of NP release in various pH buffer solutions indicated that the NP release at high pH was about 1.3 times faster than that at low pH. In addition, NP release in multi-layer biomaterials was about 4.0 times slower than that in single-layer biomaterials. It was confirmed that the NP release rate in triple-layer biomaterials was 4.0 times slower than that in single-layer biomaterials while using artificial skin. Also, it could be found that NP in double-layer biomaterials and triple-layer biomaterials was released sustainably for 12 h. The NP release mechanism in pH buffer solutions followed the Fickian diffusion mechanism, but followed the non-Fickian diffusion mechanism with artificial skin.

Effect of Vitamin D3 on Biosynthesis of Estrogen in Porcine Granulosa Cells via Modulation of Steroidogenic Enzymes

  • Hong, So-Hye;Lee, Jae-Eon;An, Sung-Min;Shin, Ye Young;Hwang, Dae Youn;Yang, Seung Yun;Cho, Seong-Keun;An, Beum-Soo
    • Toxicological Research
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    • v.33 no.1
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    • pp.49-54
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    • 2017
  • Vitamin D3 is a fat-soluble secosteroid responsible for enhancing intestinal absorption of calcium, iron, and other materials. Vitamin D3 deficiency, therefore, can cause health problems such as metabolic diseases, and bone disorder. Female sex hormones including estrogen and progesterone are biosynthesized mainly in the granulosa cells of ovary. In this study, we isolated granulosa cells from porcine ovary and cultured for the experiments. In order to examine the effect of vitamin D3 on the ovarian granulosa cells, the mRNA and protein levels of genes were analyzed by real-time PCR and Western blot assay. The production of estrogen from the granulosa cells was also measured by the ELISA assay. Genes associated with follicle growth were not significantly altered by vitamin D3. However, it increases expression of genes involved in the estrogen-biosynthesis. Further, estrogen concentrations in porcine granulosa cell-cultured media increased in response to vitamin D3. These results showed that vitamin D3 is a powerful regulator of sex steroid hormone production in porcine granulosa cells, suggesting that vitamin D deficiency may result in inappropriate sexual development of industrial animals and eventually economic loss.