• 폴리머
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• 제31권1호
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• pp.20-24
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• 2007

제조과정에서 단백질 약물의 생물학적 활성의 보존은 약물의 성공적인 전달에 있어 여전히 중요한 과제이다. 이중에멀션 유기용매 증발법을 사용하여 나노입자를 제조하였고, 입자의 형태, 크기, 함입률 그리고 방출속도와 방출되는 효소의 활성을 살펴보았다. 입자의 크기는 고분자인 락타이드 글리콜라이드 공중합체의 농도가 증가할수록 커졌으며, 유화제의 농도에는 큰 차이가 없었으나, 4% PVA의 사용에서 가장 좁은 입자분포를 얻을 수 있었다. 최적의 조건에서 72.6%의 단백질 함입률과 $198.3{\pm}13.8 nm$ 크기의 나노입자를 얻었다. 입자로부터 효소의 방출은 첫 방출시기에 매우 빠르게 일어났으며 12일 내에 83%가 방출되었다. 이에 따른 방출되는 효소의 활성은 6일째까지 증가되었다.

• 폴리머
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• 제34권2호
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• pp.172-177
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• 2010

최근 20년간 다양한 세포에서 파크리탁셀(PTX)의 효과에 관한 연구는 많이 있지만, 세포증식을 억제하기 위한 약물방출 동역학에 관한 연구는 거의 보고되지 않고 있다. 본 연구에서는 약물방출스텐트 (DES)에 적용하기 위해서 생분해성 고분자로부터 파크리탁셀의 방출거동을 고찰하였다. 다양한 생분해성 고분자인 poly(lactic acid-co-glycolic acid) (PLGA), poly-L-lactide(PLLA) 및 polycaprolactone(PCL)에 파크리탁셀의 함유량을 달리하여 필름을 제조한 후 약물방출 거동을 평가하였다. 약물방출은 8주 동안 이루어졌으며 FE-SEM을 통해 고분자의 분해정도를 관찰하였다. PCL의 생분해 속도는 가장 느리지만 파크리탁셀의 함량이 같을 경우 PCL로부터의 파크리탁셀 방출속도가 가장 빨랐으며 PLGA 그리고 PLLA 순서를 보였다. 이와 같은 결과를 바탕으로 PCL과 같이 유리전이온도($T_g$)가 낮은 고분자의 경우 체내에서 파크리탁셀과 같은 소수성 약물의 움직임이 용이하기 때문에 약물방출 속도가 빠를 수 있음을 제시하고 있다.

• Journal of Pharmaceutical Investigation
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• 제32권3호
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• pp.199-207
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• 2002

In order to develop a sustained release formulation of bovine somatotropin (BST), which has been used to increase the body weight of oxen or the milk production of dairy cows, poly(D,L-lactide-co-glyceride)(PLGA) microspheres were made by W/O/W multiple emulsification method and solvent extraction method. Physical properties including particle size, drug entrapment, drug release, protein denaturation, and in vivo body weight increase in rats were characterized. The size of the microspheres was increased as the molecular weight of PLGA increased. When Span 65 and stearic acid during preparation were added, the size was decreased but the amount of surface protein was increased, resulting in a high loading efficiency, with fast release of BST from the microspheres. Aggregation or fragmentation of BST by SDS-PAGE during microsphere preparation and drug release study was not observed. Body weight of Sprague-Dawley's male rats was significantly increased after subcutaneous administrations of BST-loaded PLGA microspheres. There was a good correlation between in vivo weight gain and in vitro release rate of microspheres. PLGA microspheres with a high surface protein ratio could be a good candidate for the sustained delivery of BST.

• 대한의용생체공학회:의공학회지
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• 제34권3호
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• pp.111-116
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• 2013

Finite element analysis(FEA) has been extensively applied in the analyses of biomechanical properties of stents. Geometrically, a closed-cell stent is an assembly of a number of repeated unit cells and exhibits periodicity in both longitudinal and circumferential directions. This study concentrates on various parameters of the FEA models for the analysis of drug-eluting biodegradable polymeric stents for application to the treatment of coronary artery disease. In order to determine the mechanical characteristics of biodegradable polymeric stents, FEA was used to model two different types of stents: tubular stents(TS) and helicoidal stents(HS). For this modeling, epigallocatechin-3-O-gallate (EGCG)-eluting poly[(L-lactide-co-${\varepsilon}$-caprolactone), PLCL] (E-PLCL) was chosen as drug-eluting stent materials. E-PLCL was prepared by blending PLCL with 5% EGCG as previously described. In addition, the effects of EGCG blending on the mechanical properties of PLCL were investigated for both types of stent models. EGCG did not affect tensile strength at break, but significantly increased elastic modulus of PLCL. It is suggested that FEA is a cost-effective method to improve the design of drug-eluting biodegradable polymeric stents.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1671-1676
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• 2015

폴리-L-유산 (PLLA)/폴리-D-유산(PDLA)의 스테레오컴플렉스(SC) 특유의 결정 거동은 PLLA/PDLA의 블렌드의 특정한 용융 조건에서 나타난다. 이를 적용하여 PLA 스테레오컴플렉스를 제조하기 위해 전반적인 조성에서 PLLA와 PDLA를 블렌드 하였다. 또한 충격 강도와 열변형온도 같은 기계적 물성 및 열적 특성을 향상시키기 위해 충격보강제, 탈크와 유리섬유(GF) 등의 보강제를 첨가하였다. 그 결과로 열변형 온도가 $115^{\circ}C$ 에서 관찰 되는 조성의 복합재를 제조하였다. 더 경제적인 방법으로, PLLA와 상용화된 폴리프로필렌(PP)을 전반적인 조성에서 블렌드 하였다. 그 결과, 특정 조성에서 상용화된 PP/탈크 복합재와 ABS에 적용시킬 수 있는 물성을 나타내었다. 이러한 결과는 PP와 PLLA같은 매트릭스 수지에 유리섬유 및 충격보강제를 잘 분산시키는 것에서 기인하는 것으로 판단된다.

• 약학회지
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• 제44권6호
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• pp.511-520
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• 2000

Various bupivacaine-loaded microspheres were prepared from poly (d,l-lactide) (PLA) or poly (d,l-lactic-co-glycolide) (PLGA) by a solvent evaporation method for the sustained release of drug. PLA and PLGA microspheres were prepared by w/o/w and w/o/o multiple emulsion solvent evaporation, respectively. The effects of process conditions such as emulsification speed, emulsifier type, emulsifier concentration and internal/external phase ratio on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their drug loading, size distribution, surface morphology and release kinetics. Drug loading efficiency was higher in the microspheres prepared by w/o/o multiple emulsion than that by w/o/w multiple emulsion method, because the solubility of bupivacaine HCI was decreased in oil phase compared with water phase. The prepared microspheres had an average diameter between 1 and $2\;{\mu}M$ in all conditions of two methods. In morphology studies the PLA microspheres showed an irregular shape and smooth surface, but PLGA microspheres had a spherical shape and smooth surface. The release pattern of the drug from microspheres was evaluated on the basis of the burst effect and the extent of the release after 24h. The in vitro release of bupivacaine HCl from microspheres showed a large initial burst release and $60{\sim}80%$ release within one day in all conditions of two methods. The extents of the burst release against PLA and PLGA microspheres were $30{\sim}50%$ and $50{\sim}80%$ within 20min, respectively. This burst release seems to be due to the smaller size of microspheres and the solubility of drug in water.

• Macromolecular Research
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• 제11권3호
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• pp.183-188
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• 2003

The controlled delivery of anticancer agents using biodegradable polymeric implant has been developed to solve the problem of penetration of blood brain barrier and severe systemic toxicity. This study was performed to prepare 5-FU-loaded poly (L-lactide-co-glycolide) (PLGA) wafer fabricated microparticles prepared by two different method and to evaluate their release profile for the application of the treatment of brain tumor. 5-FU-loaded PLGA microparticles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and differential scanning calorimetry (DSC). SEM observation of the 5-FU-loaded PLGA microparticles prepared by rotary solvent evaporation method showed that 5-FU was almost surrounded by PLGA and significant reduction of crystallinity of 5-FU was confirmed by XRD. In case of release profile of 5-FU from 5-FU-loaded PLGA wafer fabricated microparticles prepared by mechanical mixing, the release profile of 5-FU followed near first order release kinetics. In contrast to the above result, release profile of 5-FU from 5-FU-loaded PLGA wafer fabricated microparticles prepared by rotary solvent evaporation method followed near zero order release kinetics. These results indicate that preparation method of the 5-FU-loaded PLGA microparticles to fabricate into wafers was contributed to drug release profile.

• Korean Chemical Engineering Research
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• 제51권6호
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• pp.727-732
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• 2013

본 연구는 역오팔 지지체를 이용하여 인간지방유래 줄기세포의 연골 분화를 촉진하는 내용을 담고 있다. 비 다공성 구조를 가진 지지체에서 세포를 분화 시도하였을 경우 분화가 잘 촉진되지 않는 것에 비해 200 nm 정도의 균일한 구멍을 가지는 poly(D,L-lactide-co-glycolide)로 구성된 역오팔 지지체는 그 다공성 구조로 인하여 지지체의 내부까지 산소와 유기물의 수송을 가능하게 하여 지지체 내에서 어떤 유전적, 약물적 처리 없이 인간지방유래 줄기세포가 분화가 잘 되게 하는 것을 확인하였다.

• Macromolecular Research
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• 제8권6호
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• pp.276-284
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• 2000

A wettability chemogradient on poly(L-lactide-co-glycolide) (PLGA) films was prepared by treating the films in air with corona from a knife-type electrode whose power increases gradually along the sample length. The PLGA surfaces oxidized gradually with the increasing corona power, and the wettability chemogradient was created on the surfaces as evidenced by the measurement of water contact angles and electron spectroscopy for chemical analysis. The wettability chemogradient PLGA surfaces were used to investigate the interaction of four different types of cells such as hepatoma (Hep G2), osteoblast (MG 63), bovine aortic endothelial (CPAE), and fibroblast (NIH/3T3) cells in terms of the surface hydrophilicity/hydrophobicity of PLGA. The cells adhered and grown on the chemogradient surface along the sample length were counted and observed by scanning electron microscopy. It was observed that the cells were adhered, spread, and grown more onto the positions with moderate hydrophilicity of the wettability chemogradient PLGA surface than the more hydrophobic or hydrophillic positions, regardless of the cell types used. The maximum adhesion and growth of the cells appeared at around water contact angles of 53～55°. This result seems closely related with the serum protein adsorption on the surface; the serum proteins were also adsorbed more onto the positions with moderate hydrophilicity of the wettability chemogradient surface. It seems that the wettability plays important roles for cell adhesion, spreading and growth on the PLGA surface. The surface modification technique used in this study may be applicable tothe area of tissue engineering for the improvement of tissue compatibility of films- or scaffold-type substrates.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권2호
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• pp.160-163
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• 2005

This study was designed to assess skeletal stabilily after surgical correction of mandibular prognathism by bilateral saggital split ramus osteotomy(BSSRO) and fixation with absorbable screws. From July 2001 to September 2003, 30 patients with Class III malocclusion were treated with BSSRO and mandibular setback. They underwent fixation with Biosorb$^{TM}$ FX screws. Cephalograms were obtained preoperatibely, 2 or 3 days postoperatively, and about 12 months after the operation. Changes in the position of lower incisor tip, B point, and pogonion were examined on lateral cephalograms. The mean mandibular setback just after surgery was 10.6mm. 12 months after surgery, mean relapse at pogonion represented 17.9% and 15.1% at B point. Our results suggest that fixation of the bony segments with absorbable screws after BSSO may be used effectively in properly selected cases.