• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.360.1-360.1
• /
• 2016

Hydroxyapatite (Ca10(PO4)6(OH)2, HAP) particles have attracted a great deal of attention in biomedical fields due to their good biocompatibility, bioactivity and fairly broad applications as drug delivery, dental implant, bone cement, and etc. Thus, many researchers have made an effort to add new functionalities such as luminescence, drug delivery, and bone regeneration properties up to HAP powders by controlling their nanostructure as well as composition. In this research, the mesoporous strontium substituted HAP (Sr-HAP) microspheres were synthesized using a hydrothermal method. In this synthesis, aspartic acid monomers were utilized to form microsphere by controlling surface energy of HAP particles and Sr ions were substituted into Ca ion sites, which induced luminescence property in HAP powders. Moreover, the change in the amount of Sr substitution was found to influence the particle size, morphology, and concurrently surface area, which led to changing drug loading as well as drug release property. The amount of Sr influences the morphology, luminescent properties, particle size, surface area cell viability and drug loading property, which are investigated by SEM, TEM, XRD, FTIR, BET, XPS and in vitro test such as MTT assay and drug release test. In particular, the multifunctional Sr-HAP with molar ratios of 0.25 (Sr/(Ca+Sr)) possessed the strongest luminescent property as well as the superior drug loading and sustained release properties that were correspondent with large surface area and pore size. Our study indicates that the fabricated multifunctional Sr-HAP microspheres are quite useful for bone regeneration and drug delivery.

• Journal of Microbiology and Biotechnology
• /
• 제9권4호
• /
• pp.450-456
• /
• 1999

A high molecular-weight water-soluble fraction(PO) obtained by the ethanol precipitation of 0.1 N NaOH extracts of the mushroom Pleurotus ostreatus showed 82% anti-complementary activity for complement consumption hemolysis. The PO consisted of 42% carbohydrate (w/w), 50% protein (w/w), and 3% uronic acid (w/w). Fifty-eight percent of the anti-complementary activity decreased by periodate oxidation and 22% by protease digestion, suggesting that the sugar and protein moieties are essential for this activity. Two polysaccharide fractions, PO-IIIa-1 and PO-IIIa-2, with anti-complementary activity were isolated from the PO using DEAE-Sepharose FF followed by Sephadex G-75 and Sepharose CL-6B gel permeation chromatographies. The PO-IIIa-2 was found by HPLC to be nearly homogeneous, with the molecular mass of 531 kDa, and showed 96% $ITCH_{50}$ (inhibition against the total complement hemolysis of deionized water as the control) at a concentration of 1 mg/ml. This fraction contained galactose, mannose, fucose, and glucose with molar ratios of 1.75:1:0.65 and 0.59, respectively. The majority of galactose and mannose units in the PO-IIIa-2 were composed of TGalp1 ->, ->6Galp1->, ->2,6Galp1->, and ->Manp1->. The PO-IIIa-1 (molecular mass of 2000 kDa), exhibiting higher activity than the PO-IIIa-2, was further purified into two fractions, unbound proteoglycan (PO-IIIa-1A) and bound glucomannan (PO-IIIa-lB), by affinity chromatography using ConA-Sepharose CL-4B. The anti-complementary activity of each affinity purified fraction decreased as compared to that of the native PO-IIIa-1 fraction, indicating that the formation of complex between both polysaccharide fractions was necessary for full anti-complementary activity.

• 한국재료학회지
• /
• 제19권10호
• /
• pp.550-554
• /
• 2009

Unreported dielectrics based on the binary system of MgO-SiO$_2$ were investigated as potential candidates for microwave dielectric applications, particularly those demanding a high fired density and high quality factors. Extensive dielectric compositions having different molar ratios of MgO to SiO$_2$, such as 2:1, 3:1, 4:1, and 5:1, were prepared by conventional solid state reactions between MgO and SiO$_2$. 1 mol% of V$_2$O$_5$ was added to aid sintering for improved densification. The dielectric compositions were found to consist of two distinguishable phases of Mg$_2$SiO$_4$ and MgO beyond the 2:1 compositional ratio, which determined the final physical and dielectric properties of the corresponding composite samples. The increase of the ratio of MgO to SiO$_2$ tended to improve fired density and quality factor (Q) without increasing grain size. As a promising composition, the 5MgO.SiO$_2$ sample sintered at 1400 $^{\circ}C$ exhibited a low dielectric constant of 7.9 and a high Q $\times$ f (frequency) value of $\sim$99,600 at 13.7 GHz.

• Macromolecular Research
• /
• 제12권2호
• /
• pp.195-205
• /
• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• 한국식품영양학회지
• /
• 제23권4호
• /
• pp.556-561
• /
• 2010

Tomato fruits(Lycoperisicon esculentum) synthesize the glycoalkaloids dehydrotomatine and ${\alpha}$-tomatine, possibly as defense against bacteria, fungi and insects. We developed a new effective method to prepare and purify dehydrotomatine and ${\alpha}$-tomatine that exists in tomato fruits using alumina column chromatography and high performance liquid chromatography (HPLC). The tomato glycoalkaloids(TGA) in tomato was extracted with 2% acetic acid, and then precipitated with ammonium hydroxide(pH=10.5). The dry precipitate substance was applied on alumina column, and then fractionated with water saturated n-butylalcohol. The TGA(Fr. No. 26~36) were collected and dried under reduced pressure. The TGA was performed on a reverse phase HPLC(Inertsil ODS-2, $5\;{\mu}m$), eluted with acetonitrile/20mM $KH_2PO_4$(24:76, v/v) at 208 nm. Two peaks were detected on HPLC, and individual peak was collected by repeating HPLC. Furthermore, to confirm the identity dehydrotomatine and ${\alpha}$-tomatine, each peak isolated was hydrolyzed with 1N HCl into sugar and aglycone tomatidine. The sugars were converted to trimethylsilyl ester derivatives. The nature and molar ratios of sugars were identified by gas-liquid chromatography(GLC) and the aglycone by high-performance liquid chromatography(HPLC). The first peak (Rt=17.5 min) eluted from HPLC was identified as dehydrotomatine, and second peak(Rt=21.0 min) was as ${\alpha}$-tomatine. This technique has been used effectively to prepare and isolate dehydrotomatine and ${\alpha}$-tomatine from tomato fruits.

• Nutritional Sciences
• /
• 제5권4호
• /
• pp.175-183
• /
• 2002

To compare the effects of various types of dietary fiber on microbial production of short-chain fatty acids (SCFA) and on colon cell proliferation which is used as an intermediate biomarker for colon carcinogenesis, groups of 10 male Sprague-Dawley rats were fed one of four fiber-supplemented diets (6% cellulose, 6% pectin, 6% polydextrose, and a mixture of 3% cellulose and 3% polydextrose) for three weeks. As a control, a fiber-free diet was fed to a separate group of 10 rats. Cell proliferation was measured by in vivo incorporation of bromodeoxyuridine into DNA in the proximal and distal colon, respectively. Luminal concentrations of SCFA were measured by gas chromatography. Dietary fiber significantly influenced microbial production of SCFA in the colon; pectin supplementation produced the highest concentrations of luminal SCFA in both the proximal and distal colon (p<0.05). The degree of individual SCFA production was characterized by a relatively higher increase in butyrate production by the pectin-supplemented diet, and in propionate production by the polydextrose-supplemented diet, resulting in alterations of the molar ratios of acetate, propionate and butyrate. There were significant differences in colon cell proliferation among the diet groups; the pectin-supplemented diet produced a significantly higher effect on cell proliferation of distal colonic epithelial cells (p＜0.05), and the polydextrose-supplemented diet produced an intermediate effect compared to the fiber-free or cellulose-supplemented diet. Increased cell proliferation was correlated to increased luminal concentrations of butyrate in the proximal colon and to increased luminal concentrations of propionate and butyrate in the distal colon (p<0.05). Therefore, these data suggest that dietary fiber may modulate colon cell proliferation by altering luminal SCFA concentrations, particularly butyrate and perhaps propionate. In addition, the present study is the first finding that has demonstrated a relative increase in colon cell proliferation due to supplementation with polydextrose, suggesting that the overuse of this artificially synthesized polysaccharide in food processing technology needs to be carefully evaluated from the public health point of view.

• Toxicological Research
• /
• 제17권
• /
• pp.127-133
• /
• 2001

Together with cytochrome P450 (CYP), flavin-containing monooxygenase (FMO) present in liver microsomes oxidizes various endogenous and exogenous chemicals. In an effort to determine the human FMO activity, we have developed two non-invasive urine analysis methods using caffeine (CA) and ranitidine (RA) as the probe compounds. As the production of theobromine (TB) and ranitidine N-oxide (RANO) from CA and RA is catalyzed primarily by the hepatic FMO, we have assigned the urinary molar ratios of TB/CA and RA/RANO as the in vivo FMO activity. In 200 age-matched Korean volunteers, the obtained TB/CA ratio ranged from 0.4 to 15.2 (38-fold difference) and the RA/RANO ratio from 5.7 to 27.2 (4.8-fold). The FMO activity of 20's, determined by caffeine metabolism, was the highest (2.5$\pm$l.9) and those of 30's, 40's, 50's, 60's and 70's were 40%, 50%, 24%, 39% and 36% of the 20's, respectively. Intake of grapefruit juice, known to contain flavonoids, inhibited the in vivo FMO (TB/CA) activity by 79%. Addition of the flavonoids like naringin, quercitrin and kaempferol, present in grapefruit juice, to the in vitro microso-mal FMO assay, thiobenzamide S-oxidation, produced 75%, 70% and 60% inhibition, respectively. Obtained Ki values of quercitrin, kaempferol and naringin on the in vitro FMO activity were 6.2, 12.0 and 13.9 $\mu\textrm{M}$, respectively. This suggested that the dose of drug should need to be adjusted to suit the individual FMO activities when the drugs metabolized by FMO are given to patients. As the intake of grapefruit juice has been identified to inhibit the FMO as well as CYP3A4 and lA2 activities, patients taking drugs metabolized by these enzymes should not drink grapefruit juice as the carrier.

• 한국미생물·생명공학회지
• /
• 제46권1호
• /
• pp.9-17
• /
• 2018

The aims of this work were to characterize and determine bioactivities of crude exopolysaccharide (EPS) extract from Bacillus tequilensis PS21 isolated from milk kefir from Kampaeng Petch, Thailand. B. tequilensis PS21 produced 112.1 mg dried EPS/l from initial 80 g/l lactose in modified TSB media at 52 h, with EPS product yield of 8.9 mg EPS/g lactose and specific product yield of 0.3 mg EPS/mg biomass. The FTIR result confirmed EPS to be a protein-bound polysaccharide and SEM analysis showed the morphology to be a grainy appearance with an uneven surface, covered with pores. HPLC analysis determined EPS as a heteropolysaccharide consisting of five sugar units with the following molar ratios; xylose (17.65), glucose (2.54), ribose (1.83), rhamnose (1.23), and galactose (1). Chemical components of this EPS were predominantly carbohydrate at 697.8 mg/g EPS (65%), protein 361.4 mg/g EPS (34%), and nucleic acid 12.5 mg/g EPS (1%). The EPS demonstrated antioxidant activities at 57.5% DPPH scavenging activity, $37.2{\mu}M\;Fe(II)/mg$ EPS and $34.9{\mu}M\;TEAC\;{\mu}M/mg$ EPS using DPPH, FRAP and ABTS assays, respectively. EPS also exhibited anti-tyrosinase activity at 34.9% inhibition. This work represents the first finding of EPS produced by Bacillus sp. from Thai milk kefir which shows potential applications in the production of antioxidant functional foods and whitening cosmetics. However, optimization of EPS production for industrial exploitation requires further study to ascertain the economic potential.

• Asian-Australasian Journal of Animal Sciences
• /
• 제11권3호
• /
• pp.293-299
• /
• 1998

This study was undertaken to measure the concentrations of estradiol-$17{\beta}$, progesterone and testosterone, and to study their relationship with each other and with follicular size in individual buffalo ovarian follicles categorized as small (4 to 5 mm diameter), medium (6 to 9 mm diameter) and large (${\geq}10mm$ diameter). Steroid hormone concentrations varied markedly within follicles of each size category. Estradiol-$17{\beta}$ concentrations (pmol/ml) were positively related to follicular diameter (R = 0.34, n = 308, p < 0.001) and were significantly higher (p < 0.001) in large (1$118.46{\pm}30.25$), compared to those in medium follicles ($50.32{\pm}8.29$) which, in turn were significantly higher (p < 0.001) than those in small follicles ($19.70{\pm}$5.57). Progesterone and testosterone concentrations (pmol/ml) were not related to follicular diameter and were not different among small ($330.99{\pm}27.32$ and $17.68{\pm}2.44$ respectively), medium ($384.84{\pm}26.20$ and $36.47{\pm}4.55$, respectively) and large follicles ($253.25{\pm}32.23$ and $22.57{\pm}4.48$, respectively). Estradiol-$17{\beta}$ and progesterone concentrations were positively related (R = 0.39, n = 47, p < 0.01) in small, unrelated in medium and negatively related in large follicles (R = -0.59, n = 23, p < 0.01). There was no relationship between estradiol-$17{\beta}$ and testosterone concentrations in follicles of all the three size categories. Progesterone and testosterone concentrations were positively related in large follicles (R = 0.57, n = 18, p < 0.02). There was no relationship between the two hormones in small and medium sized follicles. When the follicles with estradiol-$17{\beta}$/progesterone molar ratios of > 1.00 were considered non-atretic, and the rest at different stages of atresia, 197/208(95%) follicles were found to be atretic.

• 분석과학
• /
• 제23권1호
• /
• pp.60-67
• /
• 2010

본 연구는 생물발광단백질인 aequorin을 표지물질로 사용해 신경전달물질인 serotonin에 대한 생물 발광면역분석법을 처음으로 개발하였다: serotonin-avidin 접합체는 Mannich 법으로 합성하였으며, 최적화된 avidin: formaldehyde: serotonin의 초기 몰 비는 1:12,000:25 이었다. 개발된 serotonin에 대한 생물발광면 역분석법은 좋은 감도(LOD of 0.68 ng/mL)와 넓은 검출 범위($5.0{\times}10^{-10}\;M\sim5.0{\times}10^{-7}\;M$)를 나타내었다(참고, 혈청 내 serotonin의 양은 $151{\pm}45\;ng$/mL 이다.). 교차반응성에 대한 연구 결과, 5-methoxytryptamine은 28.0% 의 교차반응성을 보인 반면, 3-methylindole, melatonin 그리고 5-hydroxylindole-3-acetic acid 은 교차반응성을 보이지 않았다. 또한, 혈청에서의 회수율은 만족할만한 값이 얻어졌다. 그러므로, 본 연구에서 제안된 생물발광면역분석법은 혈청 내의 serotonin 을 모니터링 하는데 좋은 분석법으로 사용될 수 있다.