• 폴리머
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• 제36권2호
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• pp.124-130
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• 2012

본 연구의 목적은 전기방사법을 사용하여 poly(L-lactide-$co$-${\varepsilon}$-caprolactone) (PLCL)과 marine collagen (MC)이 혼합된 나노섬유를 제조하는 것이다. 전기방사된 나노섬유의 직경과 형태는 여러 공정 변수에 의해서 변화되는데, PLCL과 MC의 혼합비, 노즐과 콜렉터와의 거리, 노즐의 직경, 용액의 방출 속도 그리고 전기장의 세기 변화에 따라 나노파이버의 직경을 주사전자현미경을 통해서 분석하였다. 또한 제조된 나노파이버의 표면변화를 확인하기 위해 물과의 접촉각을 측정하였으며, 나노파이버의 세포 친화성을 평가하기 위해 MG-63을 이용하여 생존율과 흡착형태를 주사전자현미경과 형광현미경을 통해서 관찰하였다. 이와 같은 연구 결과, 방사거리, MC의 함량, 전기장의 세기가 증가할수록 제조된 나노파이버의 평균직경은 감소하는 경향을 나타냈다. 또한 MC의 함량이 증가할수록 나노파이버의 친수성이 증가하였고 세포독성은 관찰되지 않았다. 이에 따라 해양유래 생물에서 추출한 콜라겐은 조직공학용 소재에 새롭게 사용될 수 있을 것으로 예상된다.

• Macromolecular Research
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• 제16권2호
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• pp.139-148
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• 2008

Biodegradable and elastic poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL) was electrospun to prepare nanofibers, and N-isopropylacrylamide (NIPAAm) was then grafted onto their surfaces under aqueous conditions using $^{60}Co-{\gamma}$ irradiation. The graft yield increased with increasing irradiation dose from 5 to 10 kGy and the nanofibers showed a greater graft yield compared with the firms. SEM confirmed that the PLCL nanofibers maintained an interconnected pore structure after grafting with NIPAAm. However, overdoses of irradiation led to the excessive formation of homopolymer gels on the surface of thc PLCL nanofibers. The equilibrium swelling and deswelling ratio of the PNIPAAm-g-PLCL nanofibers (prepared with 10 kGy) was the highest among the samples, which was consistent with the graft yield results. The phase-separation characteristics of PNIPAAm in aqueous conditions conferred a unique temperature-responsive swelling behavior of PNIPAAm-g-PLCL nanofibers, showing the ability to absorb a large amount of water at < $32^{\circ}C$, and abrupt collapse when the temperature was increased to $40^{\circ}C$. In accordance with the temperature-dependent changes in swelling behavior, the release rate of indomethacin and FITC-BSA loaded in PNIPAAm-g-PLCL nanofibers by a diffusion-mediated process was regulated by the change in temperature. Both model drugs demonstrated greater release rate at $40^{\circ}C$ relative to that at $25^{\circ}C$. This approach of the temperature-controlled release of drugs from PNIPAAm-g-PLCL nanofibers using gamma-ray irradiation may be used to design drugs and protein delivery carriers in various biomedical applications.

• Macromolecular Research
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• 제17권8호
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• pp.575-579
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• 2009

Copolymerization of L-lactide and s-caprolactone initiated by tin (II) octoate (Sn(Oct)$_2$) was carried out in supercritical chlorodifluoromethane (R22) with varying reaction conditions (time and temperature) and amounts of monomer and catalyst, under a pressure of 250 bar. The optimum conditions were a reaction time of 10 h and a temperature of 130 $^{\circ}C$, which is similar to the temperature used in bulk copolymerization system. The conversion increased from 56% to 76% by increasing the reaction time from 1 to 10 h. The molecular weight also increased to 75,900 g.mol$^{-1}$ over the same period, while the increased monomer concentration resulted in a high molecular weight of 86,400 g.mol$^{-1}$ and a monomer conversion of 84%. Raising the reaction temperature from 90 to 130 $^{\circ}C$ increased the monomer conversion as well as the poly-L-lactide-co-${\varepsilon}$-caprolactone (PLCL) molecular weight. The variation on the stannous octoate catalyst suggested that less catalyst would decrease the caprolactone content of the polymer.

• 폴리머
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• 제39권1호
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• pp.40-45
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• 2015

혈항혈전성 표면의 제조를 위해 간단한 비용매 휘발 방법을 통하여 고탄성체이면서 생분해성 폴리 락티드-카프로락톤 공중합체 필름의 표면상에 연잎 구조물과 유사한 마이크로 돌기를 만들어 주었다. 표면 구조와 소수성도, 항혈전 효과 등을 시험했으며, 결정화도와 탄성회복률 등의 물리적 특성도 분석하였다. 그 결과 비용매와 메틸렌클로라이드의 혼합 부피비 1:2에서 연잎표면과 유사한 최적의 효과를 얻었으며, 이때 수접촉각은 $124^{\circ}$였다. 혈소판 부착시험에서는 처리하지 않는 군에 비해 약 10%만 부착되는 효과를 확인할 수 있었다.

• 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.

• 방사선산업학회지
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• 제5권4호
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• pp.365-370
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• 2011

Electrospun nanofibers prepared with synthetic biodegradable polymer have some limitations in regulating adhesion, proliferation, and spreading of cells because of their surface hydrophobicity and absence of cell-interaction. In this study, we functionalized the electrospun poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nanofibers with acrylic acid (AAc) to modulate their surface hydrophilicity using electron-beam irradiation method and then measured grafting ratio of AAc, water contact angle, and ATR-FTIR of AAc-grafted nanofibers. A grafting ratio of AAc on the nanofibers was increased as irradiation dose and AAc concentration were increased. AAc-grafted nanofibers also have higher wettability than non-modified nanofibers. In conclusion, those surface-modified nanofibers may be an essential candidate to regulate cell attachment in tissue engineering applications.

• 방사선산업학회지
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• 제9권4호
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• pp.171-180
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• 2015

Vascular tissue engineering has been accessed to mimic the natural composition of the blood vessel containing intima, media, and adventitia layers. We fabricated mechanically expanded PLLA/PLCL nanofibers using electrospinning and UTM. The pore size of the meshes was increased the gelatin immobilized AAc-PLLA/PLCL nanofibers ($203.30{\pm}49.62microns$) than PLLA/PLCL nanofibers ($59.99{\pm}8.66microns$) after mechanical expansion. To increase the cell adhesion and proliferation, we introduced carboxyl group, and gelatin was conjugated on them. The properties of the PLLA/PLCL nanofibers were analyzed with SEM, ATR-FTIR, TBO staining, and water contact angle measurement, general cell responses on the PLLA/PLCL nanofibers such as adhesion, proliferation, and infiltration were also investigated using smooth muscle cell (SMC). During the SMC culture, the initial viability of the cells was significantly increased on the gelatin immobilized AAc-PLLA/PLCL nanofibers, and infiltration of the cells was also enhanced on them. Therefore, gelatin immobilized AAc-PLLA/PLCL nanofibers and mechanically expanded meshes may be a good tool for vascular tissue engineering application.

• 방사선산업학회지
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• 제7권1호
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• pp.45-49
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• 2013

In tissue engineering application, a fibrous structure of scaffolds has been issued as an alternative system to regulate cell survival and tissue regeneration, and electrospinning technique has been popularly used to generate fibrous meshes or sheets mimicking the structure of native extracellular matrix (ECM). However, recent strategy in the scaffold development is expanded to provide the structural property as well as a biological property of native ECM, a variety of surface modification techniques have been used to introduce biological property. In this study, we developed biomimetic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nano- and micro-fibrous scaffolds as a unique platform with structural and biological properties with native ECM using electrospinning method and gamma-ray irradiation. Surface morphology of the scaffolds was observed by scanning electron microscopy, and alteration of surface property was evaluated with toluidine blue O staining, water contact angle measurement and ATR-FTIR analysis.