• 분석과학
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• 제28권2호
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• pp.98-105
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• 2015

버얼리종 담배에서 추출물에서 얻은 peroxidase와 다중벽 탄소 나노튜브를 이용한 dopamine 정량 바이오센서를 만들었다. Peroxidase는 dopamine을 dopamine quinone으로 산화시키는 반응의 촉매 역할을 한다. 이 논문은 효소의 농도, pH와 같은 바이오센서의 감응에 영향을 주는 parameter를 조사하였다. 또한, 전극의 감도, 직선성의 범위, 전극의 안정성을 조사하였다. 본 실험에 사용한 dopamine의 정량 센서는 pH 6.50, 0.010 M 인산 완충용액, -0.15 V의 가해준 전압에서 가장 좋은 감응을 나타내었다. 전극의 검출한계(S/N ＝3)는 2.7×10⁻⁶ M이었으며, 5.0×10⁻² M dopamine을 이용하여 10회 반복 측정한 상대표준편차는 1.3%이었다.

• Journal of Pharmaceutical Investigation
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• 제31권4호
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• pp.225-232
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• 2001

The present study was carried out to observe the effect of liposome dispersed gel formulation (Lipogel) on topical delivery of ascorbyl palmitate (AsP). Neutral and negatively charged MLV liposomes containing AsP were prepared with dimyristoylphosphadtidylcholine (DMPC) and dicetyl phosphate (DCP), and dispersed to poloxamer gel matrix. In the hydrolysis study in rat's skin homogenates, AsP hydrolyzed to ascorbic acid (AsA) according to the first-order kinetics with the rate constant of $2.46{\times}10^{-2}\;min^{-1}$. In the passive skin penetration study using Franz diffusion cell, lipogel systems exhibited the greater values in the flux $(J_s)$ and the amount penetrated $(Q_p)$ compared to control hydrogels containing diethyleneglycol monoethyl ether $(Transcutol^{\circledR})$ as a solubilizing agent and a penetration enhancer for AsP. The total amount penetrated $(Q_{Total})$, which is expressed as a summation of $Q_P\;and\;Q_L$, for lipogel system was about 1.4 times higher in average than that of control hydrogel. However the amount localized in the skin $(Q_L)$ was similar in both formulations. As a result, lipogel system enhanced the skin penetration of AsP, possibly due to the increase in local concentration of AsP by preferential adsorption of liposome to the skin and the enhancing effect of phospholipid in liposome composition. Moreover it was expected that the penetrated AsP would generate AsA during skin penetration by the skin esterase. In conclusion, lipogel formulation was considered as a good candidate for topical delivery of AsP.

• International Journal of Oral Biology
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• 제30권3호
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• pp.99-103
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• 2005

Bone morphogenetic proteins (BMPs), members of a large group of TGF-beta family, are important molecular regulators of morphogenesis of numerous tissues and organs, including bones and teeth. Most BMPs are capable of inducing bone formation in vivo and therefore are of considerable clinical interest for regenerating mineralized tissues. Recently, we have developed a method to culture cells from human cementum (human cementum-derived cells, HCDCs). HCDCs, when attached to synthetic hydroxyapatite/tricalcium phosphate (HA/TCP) ceramic and transplanted into immunodeficient mice, formed histologically identifiable cementum-like tissue. Since it is unclear to what extent BMPs are involved in cementogenesis, the aim of this study was to establish which BMPs are expressed by cementogenic HCDCs and whether the expression of BMPs is related to the degree of cellular differentiation in vitro. HCDCs were maintained in growth medium (DMEM/F12 supplemented with 10% FBS) until confluent (proliferation stage). Upon reaching confluence, cells were incubated in the differentiation medium (DMEM/F12 medium containing 10% FBS and 50 mg/ml ascorbic acid) for 14 days (differentiation stage). Next, HCDCs were incubated in mineralization medium (DMEM/F12, 50 mg/ml ascorbic acid, 2.5 mg/ml of ITS (insulin-transferrinselenium), 5 mM beta-glycerophosphate and $10^{-8}M$ dexamethasone) for another 14 days (mineralization stage). At the end of each differentiation stage, total RNA was isolated and evaluated for BMPs (2 through 8) expression by employing real time RT-PCR. HCDCs expressed most of BMPs examined except BMP-7 and BMP-8. Furthermore, on average, the highest levels of BMPs were expressed at the earlier differentiation stage, prior to the initiation of mineralization in vitro. These results indicate that several BMPs are expressed during cementoblastic differentiation and suggest that BMPs may be involved in the homeostasis of human cementum.

• Current Research on Agriculture and Life Sciences
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• 제6권
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• pp.137-143
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• 1988

Straight no-time method로 조제한 냉동(冷凍)반죽을 이용(利用)한 발효(醱酵)빵제조에 있어서 가장 적절한 반죽의 조성(組成)을 제(製)빵성적(成積)을 중심으로 검토하였다. 경질(硬質)밀가루 1,000 g에 대하여 압착효모(壓搾酵母) 30 g, 설탕 50 g, 식염(食鹽) 20 g, 쇼트닝 40 g, 브롬산칼륨 75mg, L-ascorbic acid 200mg, yeast food 3 g, vital wheat gluten 30 g, 제1인산칼슘 400mg, 스테아릴젖산나트륨 8 g, 급수량(汲水量) 680 g 으로 냉동(冷凍)반죽을 만드는 것이 제(製)빵과정(過程)에서 팽창력(膨脹力)과 발효시간(醱酵時間)이 적절하고 높은 비용적(比容積)을 얻을 수 있어서 가장 바람직하였다. Farinograph 성적상의 흡수율(吸水率)보다 높은 68%의 급수량(汲水量)으로도 유화제(乳化劑)나 품질개량제(品質改良劑)의 다량첨가(多量添加)로 반죽의 동결장해(凍結障害)를 억제할 수 있었다.

• 분석과학
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• 제19권6호
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• pp.482-489
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• 2006

Pediococcus에서 추출된 lactate oxidase(LOD)를 poly(vinyl alcohol)(PVA)에 고정화하여 2전극계로 구성된 lactate 바이오센서를 제조하였다. Lactate는 LOD 효소와의 반응에서 생성되는 $H_2O_2$를 전기화학적으로 금(Au)위에 형성시킨 Pt-black 층에서 산화시켜 정량 할 수 있었다. Pt-black으로 만들어진 센서는 과산화수소에 대해서 낮은 전위(+300 mV vs. Ag/AgCl)에서 큰 산화전류를 보여주었으며, ascorbic acid, acetaminophen, uric acid 등과 같이 산화되기 쉬운 산화 종들의 영향을 감소시켜주었다. 외부보호막으로는 다양한 종류의 친수성 폴리우레탄을 사용하였다. 센서는 in vitro 방식으로 흐름계와 비흐름계 모두에서 성능을 평가하였다. 제작된 센서는 0.05 M NaCl을 포함하는 0.05 M 인산염 완충용액(pH 7.6)에서 성능을 시험하였으며, 0.1 mM에서 9.0 mM의 lactate 농도구간에서 직선적 감응성을 나타내었다. 최적화된 센서는 $4^{\circ}C$ 완충용액에 보관하였으며, 25일 이상 감응도(sensitivity)가 거의 변화하지 않았다.

• 대한의생명과학회지
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• 제22권1호
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• pp.1-8
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• 2016

Several studies have investigated the various effects of dexamethasone (Dex) on the proliferation and differentiation of mesenchymal stem cells (MSCs). Previously, we reported that co-treatment with L-ascorbic acid 2-phosphate and fibroblast growth factor (FGF)-2 maintained differentiation potential in MSCs through expression of hepatocyte growth factor (HGF). In this study, we investigated the effects of co-treatment with FGF-2 and Dex on the proliferation and differentiation potential of MSCs during a 2-month culture period. Co-treatment with FGF-2 and Dex increased approximately a 4.7-fold higher accumulation rate of MSC numbers than that by FGF-2 single treatment during a 2-month culture period. Interestingly, co-treatment with FGF-2 and Dex increased expression of HGF and maintained adipogenic differentiation potential during this culture period. These results suggest that co-treatment with FGF-2 and Dex preserves the proliferation and differentiation potential during long-term culture.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2002년도 제9차 국제심포지움 및 추계정기학술발표회
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• pp.53-53
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• 2002

Shoot tips of in vitro propagated plantlets were cryopreserved using encapsulation/dehydration procedures. Shoot tips were excised under filter sterilized antioxidants solution (0.2M phosphate buffer, pH 5.7 supplemented with 5g/1 ascorbic acid and 15g/1 sodium borate). They were drawn up into a sterile 10 $\textrm{cm}^3$disposable pipette and were dropped into the culture medium with 2.5w/v Na-alginate, then into 100mM CaCl$_2$.2$H_2O$. Encapsulated shoot tips were transferred into 10㎤ of liquid culture medium with a range of sucrose concentrations (0.25-1.0M) and were incubated in dark for 24 hours in 18C at 40rpm. Beads were then dehydrated in silica gel for different time intervals (1-24 hours). Then they were freeze dried either rapidly (plunge directly into liquid N2 or in two stages (samples were kept at 20C for 10 minutes, then reduced to 35C at 1C per minute. Then, plunge into liquid $N_2$). The influence of sucrose and silica gel pre-treatment on pre- and post-freeze shoot growth was examined.(중략)

• JSTS:Journal of Semiconductor Technology and Science
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• 제7권3호
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• pp.161-165
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• 2007

In this paper, mesoporous Pt on micro pillars Pt electrode is newly designed, fabricated, and characterized on silicon substrate for non-enzymatic electrochemical sensor micro-chip integrated with CMOS readout circuitry. The fabricated micro/nano Pt electrode has cylindrical hexangular arrayed nano Pt pores with a diameter of 3.2 nm which is formed on top of the micro pillars Pt electrode with approximately $6{\mu}m$ in diameter, $6{\mu}m$ in space, and $50{\mu}m$ in height. The measured current responses of the fabricated plane Pt, mesoporous Pt, and mesoporous Pt on the micro pillar Pt electrodes are approximately $9.9nA/mm^2,\;6.72{\mu}A/mm^2,\;and\;7.67{\mu}A/mm^2$ in 10mM glucose solution with 0.1M phosphate buffered saline (PBS) solution, respectively. In addition, the measured current responses of the fabricated plane Pt, mesoporous Pt, and mesoporous Pt on the micro pillar Pt electrodes are approximately $0.15{\mu}A/mm^2,\;0.56{\mu}A/mm^2,\;and\;0.74{\mu}A/mm^2$ in 0.1mM ascorbic acid (AA) solution with 0.1M phosphate buffered saline (PBS) solution, respectively. This experimental results show that the proposed micro/nano Pt electrode is highly sensitive and promising for CMOS integrated non-enzymatic electrochemical sensor applications. Since the micro-pillar Pt electrode can also be utilized with a micro-fluidic mixer in the sensor chip, the sensor chip can be much smaller, cheaper, and easier to be fabricated.

• 분석과학
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• 제20권5호
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• pp.393-399
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• 2007

본 연구에서는 갈락토오즈의 현장검사(point-of-care testing, POCT)를 위한 일회용 갈락토오즈 바이오센서 개발에 관해 논하고자 한다. Galactose oxidase(GAO)와 horseradish peroxidase(HRP) 두 효소를 0.05 M phosphate 완충용액에 용해시킨 후 스크린 프린팅(screen printing) 방법으로 제작한 전극위에 고정화하여 센서를 제작하였다. 이렇게 제작된 센서를 이용하여 $100{\mu}L$ 이하의 시료를 이용하여 갈락토오즈를 90초 이내에 측정하였다. 전극에서의 반응을 최적화하기 위하여 GAO 효소가 가장 우수한 활성을 나타내는 pH 7.0 완충용액을 이용하여 GAO와 HRP 효소를 1:1로 고정화하고, 1mM 1,1'-ferrocene-dimethanol 전자전달매개체를 도입하여 센서를 제작하였다. 유리 탄소전극의 경우 100 mV (vs Ag/AgCl), 스크린 프린트된 전극의 경우 -100 mV(vs Ag/AgCl)의 인가전압을 적용하였다. 본 연구에 의해 개발된 센서는 $0{\sim}400{\mu}M$의 갈락토오즈 농도에 대하여 우수한 직선성($r^2$ = 0.997, S/N = 3)을 나타내었고 낮은 인가전압을 적용하여 갈락토오즈를 측정하므로, ascorbic acid, uric acid 그리고 acetaminophen과 같은 방해물질의 영향을 최소화 할 수 있었다. 또한 갈락토오즈 표준 용액에 대하여 만족할 만한 재현성을 나타내었다(CV = 5%).

• BMB Reports
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• 제43권10호
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• pp.688-692
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• 2010

In a previous study, we recently claimed that dihydrotestosterone (DHT)-inducible dickkopf-1 (DKK-1) expression is one of the key factors involved in androgen-potentiated balding. We also demonstrated that L-ascorbic acid 2-phosphate (Asc 2-P) represses DHT-induced DKK-1 expression in cultured dermal papilla cells (DPCs). Here, we investigated whether or not L-threonate could attenuate DHT-induced DKK-1 expression. We observed via RT-PCR analysis and enzyme-linked immunosorbent assay that DHT-induced DKK-1 expression was attenuated in the presence of L-threonate. We also found that DHT-induced activation of DKK-1 promoter activity was significantly repressed by L-threonate. Moreover, a co-culture system featuring outer root sheath (ORS) keratinocytes and DPCs showed that DHT inhibited the growth of ORS cells, which was then significantly reversed by L-threonate. Collectively, these results indicate that L-threonate inhibited DKK-1 expression in DPCs and therefore is a good treatment for the prevention of androgen-driven balding.