초록 ▼

생체 분해성 고분자 재료의 물성을 고상압출법을 사용하여 증가시킴에 았어서 결정화도 및 배향도의 증가에 의한 강도 증가뿐만 아니라 생체 분해성 고분자 재료의 분자량 감소를 최소화시킬 수 있는 공정을 도입함으로써 강도 저하를 방지하여 원하는 물성을 얻고자 하며 또한 공정-구조-물성간 상관 관계 연구를 통하여 요구 되는 물성을 부여하는 공정 조건을 확립한다. 소 심막을 이용하여 기계적 강도와 체내 안정성을 증가시키기 위한 화학적 처리 방법을 개발하고 혈액 응고능이 탁월하고 혈액 적합성 개선에 많이 이용되는 glycosaminoglycan

생체 분해성 고분자 재료의 물성을 고상압출법을 사용하여 증가시킴에 았어서 결정화도 및 배향도의 증가에 의한 강도 증가뿐만 아니라 생체 분해성 고분자 재료의 분자량 감소를 최소화시킬 수 있는 공정을 도입함으로써 강도 저하를 방지하여 원하는 물성을 얻고자 하며 또한 공정-구조-물성간 상관 관계 연구를 통하여 요구 되는 물성을 부여하는 공정 조건을 확립한다. 소 심막을 이용하여 기계적 강도와 체내 안정성을 증가시키기 위한 화학적 처리 방법을 개발하고 혈액 응고능이 탁월하고 혈액 적합성 개선에 많이 이용되는 glycosaminoglycan인 헤파린을 고정화함으로써 생체내에서 칼슘화를 방지하기 위한 연구를 수행하였다 조직공학 분야에서 고분자 지지체는 조직형성을 유도하거나 조직과의 상호작용을 방해하는 분야에 널리 응용되고 있다. 따라서 지지체는 우수한 생체적합성, 적절한 생분해성 및 특정 세포와 상호작용 할 수 있는 능력 등의 특성을 가져야 한다. 본 연구에서 새로운 lactide 기반 poly(ethylene glycol) (PEG) 고분자 network을 glycerol 함유 triacrylated oligolactide와 PEG-acrylate (PEG-Ac)의 두 개의 무독성 고분자를 사용하여 제조하였다. 이러한 특성의 GL-PEG 지지체에 PEG 말단에 세포 특이성을 같은 bioactive 펩타이드 리간드를 그라프트함으로써 조직공학을 위한 고분자 지지체로서 매우 유용하리라 기대된다.모델 콜로이드 용액의 실제 막여과 실험을 수행하여 여과 시간에 따른 막오염 특성을 연속적으로 관측할 수 있는 멤브레인 전위의 in-situ계측기법을 연구 · 개발하였고, 고분자 입자의 정전기적 특성에 따른 막여과 특성과 막표면에서 용질 입자의 확산 거동에 관한 새로운 실험결과와 해석을 제시하였다.

Abstract ▼

Solid-state extrusion was utilized for the improvement of mechanical properties of polylactide (PLLA), and in the middle of the process vacuum compression molding was employed for the minimization of the decrease in molecular weight. For the solid-state extrusion process, relationship among the proc

Solid-state extrusion was utilized for the improvement of mechanical properties of polylactide (PLLA), and in the middle of the process vacuum compression molding was employed for the minimization of the decrease in molecular weight. For the solid-state extrusion process, relationship among the process conditions-microstructure-mechanical properties was investigated with such major process controlling factors as billet crystallinity, draw ratio, and drawing rate. As the draw ratio increased, PLLA crystalline structure was developed and the crystalline orientation factor was increased. The overall orientation increased with increasing billet crystallinity, draw ratio, and drawing rate. Solid-state extrudated rods showed no cold crystallization behavior and their melting enthalpies increased with draw ratio. Flexural modulus and strength had higher values at higher billet crystallinity and draw ratio. With increasing drawing rate, crystallinity showed little difference but birefringence and flexural strengths increased. The effect of drawing rate was thought to be transformed into that of draw ratio. As a result, the increase in crystallinity and birefringence led to the increase in flexural strengths. From the linear regression results, birefringence-flexural modulus was found to have good linear relationship and the limit values of internal structure factors could be revealed for the required mechanical properties. In this way process-structure-property relation in the solid-state extrusion of PLLA was established and can possibly be utilized for the production of the biodegradable bone implant fulfilling the requirements of strengths. Novel calcification-resistant tissue patch for cardiovascular implant has been developed. For prevent calcification, biological bovine pericardium (BP) was modified by the direct coupling of heparin. Heparinized BP was also evaluated in vitro and in vivo for the effect of modification. Thermal and mechanical properties measured by DSC and mechanical test machine showed that durability of heparin treated tissue significantly increased as compared with fresh and GA treated tissue. Resistance to collagenase digestion revealed that heparin treated tissue has greater resistance to enzyme digestion than do fresh tissue and GA treated tissue. Also, heparinized tissue has shown to be non-cytotoxic. However, relatively high cytotoxicity observed in the GA treated tissues possible due to the release of GA. From in vivo calcification results, calcium contents deposited on heparin treated tissue were much less than those of GA treated tissue. Glucosaminoglycans are natural inhibitors of calcification. In particular, the heparin molecule is highly negatively charged due to the presence of many sulfates and carboxyl groups, and this charge may cause the ionic repulsion of potential apatite crystal. In addition, heparinized BP is expected to be blood compatible due to anticoagulant activity of heparin. From these results, it was demonstrated that each approaches could be a useful calcification-resistant treatment for implantable tissue patches. New lactide-based poly(ethylene glycol) (PEG) polymer networks (GL-PEGs) have been prepared by UV photopolymerization using two nontoxic macromers, triacrylated lactic acid oligomer emanating from a glycerol center (GL) and monoacrylated PEG. These materials have been developed for use as polymer scaffolds in tissue engineering, which have cell-adhesion resistant, ligand-immobilizable, and biodegradable characteristics. The GL-PEG crosslinked polymer networks obtained were glassy and transparent, and the gel content was approximately 90%, irrespective of the degree of polymerization of lactide on the glycerol center and the amount and molecular weight of the PEG acrylate incorporated. All networks showed relatively low swelling in water, due to the high crosslink density. They had no melting endotherms, but displayed glass transition temperatures indicative of phase-mixing of the PEG. Analysis by ESCA and contact angle measurement indicated the presence of PEG at the network surfaces and showed that higher molecular weight PEG was incorporated into the network surfaces to a higher extent, rendered the surfaces more hydrophilic. GL-PEG scaffolds demonstrated unique thermal properties and relatively low tensile strength as compared to GL network. GL-PEG scaffolds also have shown to be degraded faster than GL network due to hydrophilic PEG. Given that the terminal hydroxyl function on the incorporated PEG can be readily derivatized with a bioactive peptide, these degradable networks should be useful as polymer scaffolds for tissue engineering. The streaming potential generated by the electrokinetic flow effect within electric double layer of charged channel is applied to determine the membrane potential by using the Helmholtz-Smoluchowski equation. It is known that the membrane potential depends on the particle concentration, solution ionic strength, and cake layer formed during the progress of filtration. The influence of physicochemical parameters upon the filtration has been examined with an in-situ and simultaneously monitoring of membrane potential as well as permeate flux. As the latex concentration increases, both permeate flux and membrane potential are decreased. Evidently, the growth of cake layer has been more developed with increasing latex concentration, and then both a lower permeate velocity and a higher solution conductivity lead to decrease the membrane potential. With increasing ionic concentration of KCI from 0.1 to 10 mM, the opposite behavior has been observed, where the permeate flux decreases but the membrane potential increases. Note that the increase of ionic concentration provides a denser cake layer due to the shrinkage of Debye length, and the increased membrane potential results from a corresponding zeta potential. The permeate flux of fully retentive dead-end ultrafiltration has been monitored with the progress of filtration time, so as to understand a membrane fouling mechanism due to the consistent formation of cake layer. We selected the polystyrene latex negatively charged upon surfaces as well as the flat membrane having asymmetric pores as a model colloid and a model membrane, respectively, and their zeta potentials were characterized. As the transmembrane pressure difference Δp increases, the permeate flux also increases, while it shows a decreasing behavior with increasing solution ionic strength. Note that the effect of solution ionic strength on the permeate flux is found to increase, as the Δp decreases. For the Δp of 4 psi, the permeate flux at KCI 100 mM was decreased by about 16 % compared to the flux at KCI 0.01 mM. It is obvious that, as the solution ionic strength decreases, the estimated specific cake resistance decreases, but the cake compressibility is increased. This phenomena allow us to analyze the long-range electrostatic interaction between pairs of suspended latex particles, in which the expanded double layer around particle surfaces with decreasing solution ionic strength provides the development of loosely packed cake layer during the membrane filtration.

목차 Contents

• 제1부 생체 흡수성 고분자 소재 개발 (E 16212)...19
• 제1장 서 론...23
• 제2장 실 험...27
• 제1절 시 약...27
• 제2절 고상압출...27
• 1. 시료 준비...27
• 2. 진공 압축성형...27
• 3. 고상압출...27
• 제3절 분 석...28
• 1. 시차주사 열량 분석...28
• 2. 겔 투과 크로마토그래피...28
• 3. 광각 X-선 산란...28
• 4. 복굴절...29
• 5. 기계적 물성...29
• 제3장 결과 및 고찰...33
• 제1절 진공 압축성형...33
• 1. 진공 압축성형물의 물리적 성질...33
• 제2절 고상압출...35
• 1. 고상압출물의 연신비...35
• 2. 고상압출물의 결정 구조...39
• 3. 고상압출물의 분자 배향...43
• 4. 고상압출물의 열적 성질...45
• 5. 고상압출물의 역학적 성질...48
• 제3절 고상압출물의 물성...50
• 1. 고상압출물의 공정 조건-물성 관계...50
• 2. 고상압출물의 구조-물성 관계...53
• 제4장 결 론...57
• 참고문헌...59
• 제2부 헤파린이 고정화 된 항칼슘성 조직 패취 개발 (E 16212)...61
• 제1장 서 론...65
• 제2장 실 험...68
• 제1절 재료 및 시약...68
• 제2절 패취의 헤파린 고정화...69
• 제3절 헤파린 고정화 정도...69
• 제4절 열적안정성...69
• 제5절 효소분해저항성...72
• 제6절 기계적 강도...72
• 제7절 박테리아 점착 시험...72
• 제8절 세포독성 시험...73
• 제9절 In-vivo 칼슘화 시험...73
• 제10절 통계적 분석...74
• 제3장 결과 및 고찰...74
• 제1절 조직 패취의 헤파린 고정화...74
• 제2절 헤파린의 고정화 정도...78
• 제3절 열적안정성 평가...78
• 제4절 효소분해안정성...79
• 제5절 기계적 성질...80
• 제6절 박테리아 점착...80
• 제7절 세포독성 평가...83
• 제8절 In-vivo 칼슘화 실험...85
• 제4장 결 론...88
• 참고문헌...89
• 제3부 항응혈성 고분자 지지체 연구 (E 16213)...91
• 제1장 서 론...95
• 제2장 실 험...99
• 제1절 재료 및 시약...99
• 제2절 Glycerol-Lactide (GL) triol의 합성...99
• 제3절 Triacylated Glycerol-Lactide (GL-Ac)의 합성...102
• 제4절 GL9-PEG network의 제조...102
• 제5절 특성 분석...104
• 제3장 결과 및 고찰...105
• 제1절 GL triol과 GL-Ac의 합성...105
• 제2절 GL9-PEG network의 벌크 특성...109
• 제3절 GL9-PEG network의 표면 특성...114
• 제4절 GL9-PEG network의 생분해 특성...117
• 제4장 결 론...123
• 참고문헌...125
• 제4부 생체고분자의 막여과 (E 16211)...129
• 제1장 서 론...133
• 제2장 콜로이드입자의 여과에 따른 멤브레인 전위...135
• 제1절 연구 배경...135
• 제2절 계면동전기와 흐름전위의 원리...136
• 제3절 멤브레인 전위 측정 실험...138
• 1. 막과 모델 라텍스...138
• 2. 멤브레인 전위 측정 시스템...138
• 제4절 결과 및 논의...140
• 1. 멤브레인 전위 측정 결과...140
• 2. 라텍스 입자의 제타전위 거동...144
• 3. in-situ 멤브레인 전위의 거동과 투과플럭스 고찰...146
• 사용기호...152
• 참고문헌...153
• 제3장 콜로이드 현탁액의 dead-end 막여과에서 투과플럭스ad-end 여과방식의 기본원리...155
• 1. Darcy의 법칙과 투과 플럭스...155
• 2. 저항...157
• 3. 확산원리...158
• 4. 입자의 압축률 (compressibility)...159
• 제3절 투과플럭스 측정실험...160
• 1. 멤브레인과 콜로이드 물질...160
• 2. 투과 플럭스 측정 시스템...161
• 제4절 결과 및 고찰...162
• 1. 멤브레인 전위...162
• 2. 투과 플럭스 변화...163
• 3. 저항과 확산계수의 산출...167
• 4. 압축률 비교 분석...173
• 사용기호...175
• 참고문헌...177
• 제4장 결 론...179