• 폴리머
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• 제32권6호
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• pp.544-548
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• 2008

본 연구에서는 키틴의 알칼리 가수분해를 통해 탈아세틸화도가 조절된 세 가지 조건의 키토산을 제조하였고, 이 키토산이 수용성을 지니게 화학적 분해법을 이용해 분자량을 조절하였다. 이렇게 제조된 분자량이 조절된 세 가지 조건의 탈아세틸화도를 가지는 키토산 각각에 항산화제인 리포산을 합성하여 항산화 능력을 가지는 생체 적합성 나노 구조체를 형성하였다. 키토산-리포산의 합성을 확인하기 위하여 분광학적 분석 방법을 사용하여 분석하였다. 키토산-리포산 합성체는 수용액 상태에서 자기조립체를 형성하며 이렇게 형성된 자기조립체 나노 입자는 약 135 nm 정도의 크기를 가지고 있음을 알 수 있었다.

• Steel and Composite Structures
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• 제28권2호
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• pp.195-207
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• 2018

First-order reliability method (FORM) is enhanced based on the search direction using relaxed conjugate reliability (RCR) approach for the embedded nanocomposite beam under buckling failure mode. The RCR method is formulated using discrete conjugate map with a limited scalar factor. A dynamical relaxed factor is proposed to control instability of proposed RCR, which is adjusted using sufficient descent condition. The characteristic of equivalent materials for nanocomposite beam are obtained by micro-electro-mechanical model. The probabilistic model of nanocomposite beam is simulated using the sinusoidal shear deformation theory (SSDT). The beam is subjected to external applied voltage in thickness direction and the surrounding elastic medium is modeled by Pasternak foundation. The governing equations are derived in terms of energy method and Hamilton's principal. Using exact solution, the implicit buckling limit state function of nanocomposite beam is proposed, which is involved various random variables including thickness of beam, length of beam, spring constant of foundation, shear constant of foundation, applied voltage, and volume fraction of ZnO nanoparticles in polymer. The robustness, accuracy and efficiency of proposed RCR method are evaluated for this engineering structural reliability problem. The results demonstrate that proposed RCR method is more accurate and robust than the excising reliability methods-based FORM. The volume fraction of ZnO nanoparticles and the applied voltage are the sensitive variables on the reliable levels of the nanocomposite beams.

• 한국축산시설환경학회지
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• 제8권3호
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• pp.145-152
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• 2002

Slurry type 고농도 양돈분뇨의 퇴비화과정에서 발생하는 침출수를 응집침전 방법으로 처리시 그 효과를 검증하기 위하여 본 실험을 실시하였다. 이를 위해 퇴비화가 주목적인 완전혼합식 진천시 소재 A양돈장 퇴비단침출수와 정화처리를 위해 침출수 배출이 주목적인 이천시 소재 B양돈장 퇴비단 침출수의 응집침전 실험을 수행하였으며, 그 결과는 다음과 같다. 1. A양돈장 퇴비단 침출수의 응집실험 결과, 적정 농도는 Alum 750mg/l, 양이온 폴리머는 62.5mg/l이었으며 $BOD_5$, T-N, T-P의 농도는 각각 19, 257.5, 0.4mg/l로 축산 폐수처리시설의 방류수 수질기준에 적합한 처리 효율을 보였다. 2. B양돈장 퇴비단 침출수의 응집실험 결과, 적정 농도는 $FeCl_3$, 1,500mg/l와 FO4240 l0mg/l이었으며 $BOD_5$, T-N, T-P의 농도는 각각 15.3, 829.4, 2.8mg/l로 축산폐수처리 시설의 방류수 수질기준에는 T-N 농도가 높아 부적합하였다. 이는 침출수내 암모니아성 질소의 농도가 높았기 때문으로 사료된다. 3. 개별 축산농가의 퇴비단 침출수 처리를 위해서는 침출수 내 암모니아성 질소의 농도가 낮을 경우 응집 침전에 의한 처리만으로도 방류수 수질기준에 도달할 수 있으나, 암모니아성 질소의 농도가 높을 경우에는 후단에 생물학적 처리 시설이 필요할 것으로 판단된다.

• Macromolecular Research
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• 제12권5호
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• pp.534-539
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• 2004

Two biopolymers, silk fibroin (SF) and chitosan, were conjugated by tyrosinase (EC 1.14.18.1), a polyphenolic oxidase, to improve their physicochemical properties, such as their thermal properties and morphological stabilities in organic solvents. The crosslinking between SF and chitosan took place mainly through Michael addition reactions. A main reaction between the amino groups in chitosan and o-quinone, the oxidation product of the tyrosyl residue in SF, was confirmed by UV spectroscopy. Measurements of viscosity and light scattering indicated that the crosslinked SF/chitosan conjugate was compact: it had a smaller particle size because of tight bonding forces between the SF and chitosan molecular chains. Thermal decomposition of SF/chitosan conjugates crosslinked by tyrosinase occurred at higher temperatures. The adhesiveness of the SF/chitosan conjugates decreased steadily as the crosslinking reaction progressed. We propose that this new crosslinking method be used for the preparation of silk fibroin/chitosan conjugates using tyrosinase. We expect that SF/chitosan conjugates crosslinked by tyrosinase can be used preferentially in biomedical applications because of its unique properties and non-toxicity.

• Macromolecular Research
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• 제17권2호
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• pp.79-83
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• 2009

The oral delivery of heparin is the preferred therapy in the treatment of patients with a high risk of deep vein thrombosis and pulmonary embolism. New conjugates of heparin and sodium deoxycholate were synthesized in order to enhance the heparin absorption in the GI tract. After oral administration of DOC-heparin, the concentration in anti-FXa assay was increased with increasing amount of coupled DOC. The maximum concentration of DOC-heparin VIII conjugate was $3.3{\pm}0.5\;IU/mL$ at an oral dose of 10 mg/kg, which was 3-fold higher than the baseline level. Finally, DOC coupled to heparin greatly enhanced the absorption of heparin in the GI tract, and this enhancing effect was not induced by changing the tissue structure of the GI wall.

• Macromolecular Research
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• 제14권6호
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• pp.646-653
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• 2006

Highly hydrophilic, uniform, superparamagnetic and nontoxic maltotrionic acid (MA)-coated magnetite nano-particles (MAM) were prepared and characterized by TEM, DLS, XRD and VSM. MA was used to improve the biocompatibility, monodispersity and non-specific intracellular uptake of nanoparticles. Folic acid (FA) was subsequently conjugated to the MAM to preferentially target KB cells (cancer cells) that have folate receptors expressed on their surfaces and to facilitate nanoparticles in their transit across the cell membrane. Finally, fluorescence isothiocyanate (FITC) was added to the nanoparticles to visualize the nanoparticle internalization into KB cells. After the cells were cultured in a media containing the MAM and MAM-folate conjugate (FAMAM), the results of fluorescence and confocal microscopy showed that both types of nanoparticles were internalized into the cells. Nevertheless, the amount of FAMAM uptake was higher than that of MAM. This result indicated that nanoparticles modified with MA and FA could be used to facilitate the nanoparticle uptake to specific KB cells (cancer cells) for molecular imaging.

• The Korean Journal of Physiology and Pharmacology
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• 제27권1호
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• pp.31-38
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• 2023

Carboplatin, an advanced anticancer drug with excellent efficacy against ovarian cancer, was developed to alleviate the side effects that often occur with cisplatin and other platinum-based compounds. Our study reports the in vitro characteristics, viability, and activity of cells expressing the inducible nitric oxide synthase (iNOS) gene after carboplatin was conjugated with polysuccinimide (PSI) and administered in combination with other widely used anticancer drugs. PSI, which has promising properties as a drug delivery material, could provide a platform for prolonging carboplatin release, regulating its dosage, and improving its side effects. The iNOS gene has been shown to play an important role in both cancer cell survival and inhibition. Herein, we synthesized a PSI-carboplatin conjugate to create a modified anticancer agent and confirmed its successful conjugation. To ensure its solubility in water, we further modified the structure of the PSI-carboplatin conjugate with 2-aminoethanol groups. To validate its biological characteristics, the ovarian cancer cell line SKOV-3 and normal ovarian Chinese hamster ovary cells were treated with the PSI-carboplatin conjugate alone and in combination with paclitaxel and topotecan, both of which are used in conventional chemotherapy. Notably, PSI-carboplatin conjugation can be used to predict changes in the genes involved in cancer growth and inhibition. In conclusion, combination treatment with the newly synthesized polymer-carboplatin conjugate and paclitaxel displayed anticancer activity against ovarian cancer cells but was not toxic to normal ovarian cancer cells, resulting in the development of an effective candidate anticancer drug without severe side effects.

• 대한약학회:학술대회논문집
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• 대한약학회 2001년도 Proceedings of International Convention of the Pharmaceutical Society of Korea
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• pp.289.3-290
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• 2001

• Korean Chemical Engineering Research
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• 제46권2호
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• pp.211-216
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• 2008

아토피의 치료를 위해 사용되는 부펙사막은 연고제 형태로 사용되는 약물이다. 부펙사막은 피부 장벽효과에 의해 실제 전달되는 양은 매우 적다. 이러한 문제를 갖는 부펙사막의 피부전달 효율을 증가시키기 위하여 마이크로니들을 이용해 피부처리를 실시하였다. 약물의 피부투과량과 피부에서 약물의 전달형태를 알아보기 위하여 부펙사막에 FITC를 결합시켰으며 이를 포함하는 하이드로겔을 제조하여 피부에 도포하였다. 약물의 피부투과량을 확인하기 위해서 형광분광계를 사용하여 분석하였으며 약물의 전달형태를 확인하기 위하여 형광필터가 장착된 마이크로현미경을 사용하였다. 실험결과 마이크로니들로 처리된 피부에서 부펙사막의 피부투과량이 대조군에 비해 5~20배 이상 증가되었으며 마이크로니들 처리횟수가 증가함에 따라서 더 크게 증가될 수 있음을 확인하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.141-144
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• 2000

Highly open porous polymer matrices are required for high density cell seeding, efficient nutrient, and oxygen supply to the cells cultured in the three dimensional matrices. However, there are severe problems of mass transfer limitations within the cell/scaffolds culture system. Thus we hypothesize that continuos-flow culture conditioning of cells with the scaffolds may improve the cell viability and the differentiated function. In this study, we fabricated porous PLGA scaffolds by using gas-foaming/salt-leaching method as previous described. Viscous PLGA gel paste contains ammonium bicarbonate particulates, acting as a gas-foaming agent as well as a salt-leaching porogen, were cast into Teflon mold and dried. Ammonium bicarbonate salt upon contact to an acidic aqueous solution evloves gaseous ammonia and carbon dioxide by itself. And we conjugated galactose moiety [AGA; $N-(aminobuty1)-O-{\beta}-D-galactopyranosyl-(1{\rightarrow}4)-D-glucoamide]$ to the terminal end group of a PLGA to increase the cell adhesion and matain the differentiated function of hepatocytes. Cell-seeded scaffolds were secured in a flow bioreactor chamber and exposed to continuous flow at 5 ml/min. As a result of our study, the high yield of hepatocytes attachment was accomplished by increasing the concentration of PLGA-AGA conjugate in polymer scaffolds and cells in the scaffolds under continuos flow condition maintained a high level of viability and albumin secretion rate of cultured hepatocytes showed a higher level that of control groups.