• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.408.2-409
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• 2002

The aim of this study is to prepare biodegradable microspheres without use of any kind of surfactants or emulsifiers for a novel sustained delivery carriers of protein drugs. Poly(e-caprolactone)/poly(ethylene glycol)/poly(e-caprolactone) (CEC) triblock copolymer was synthesized by ring-opening of e-caprolactone with dihydroxy poly(ethylene glycol) and was used to make surfactant-free microspheres. (omitted)

• Macromolecular Research
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• 제16권7호
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• pp.609-613
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• 2008

Poly($\varepsilon$-caprolactone)-poly(ethylene glycol)-poly($\varepsilon$-caprolactone) (PCL-PEG-PCL) multiblock copolymers at various hydrophobic-hydrophilic ratios were successfully synthesized by the chain extension of triblock copolymers through isocyanate (hexamethylene diisocyanate). Biodegradable films were prepared from the resulting multiblock copolymers using the casting method. The mechanical properties of the films were improved by chain extension of the triblock copolymers, whereas the films prepared by the triblock copolymers were weak and brittle. Atomic force microscopy (AFM) of the multiblock copolymer film showed that the hydrophilic PEG had segregated on the film surface. This is consistent with the observed contact angle of the films.

• 폴리머
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• 제33권2호
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• pp.137-143
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• 2009

이 연구에서 norfloxacin(NFX)이 담지된 poly($\varepsilon$-caprolactone)/poly(ethylene glycol)(PCL/PEG, abbreviated as CE) 이중블록공중합체로 구성된 고분자 미셀을 제조하였다. 입자크기는 PCL블록길이에 따라 60$\sim$200 nm사이였다. 임계회합농도는 소수성 PCL 블록길이가 증가함에 따라 감소하는 경향을 보였다. $^1H$-NMR 연구에서 PCL 블록은 내핵, PEG는 외피를 형성한 미셀구조로 형성되었음을 확인하였다. 약물의 방출은 약 2일간 지속되었으며 PCL블록길이와 약물함량이 증가함에 따라 감소하는 경향을 보였다. 항미생물 성능 실험에서 고분자 미셀은 기존의 NFX와 비슷한 독성을 보였다.

• Archives of Pharmacal Research
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• 제26권6호
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• pp.504-510
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• 2003

The aim of this study is to prepare biodegradable microspheres without the use of surfactants or emulsifiers for a novel sustained delivery carriers of protein drugs. A poly($\varepsilon$-caprolactone)/poly(ethylene glycol)/poly($\varepsilon$-caprolactone) (CEC) triblock copolymer was synthesized by the ring-opening of $\varepsilon$-caprolactone with dihydroxy poly (ethylene glycol) to prepare surfactant-free microspheres. When dichloromethane (DCM) or ethyl formate (EF) was used as a solvent, the formation of microspheres did not occur. Although the microspheres could be formed prior to lyophilization under certain conditions, the morphology of microspheres was not maintained during the filtration and lyophilization process. Surfactant-free microspheres were only formed when ethyl acetate (EA) was used as the organic solvent and showed good spherical micro-spheres although the surfaces appeared irregular. The content of the protein in the micro-sphere was lower than expected, probably because of the presence of water channels and pores. The protein release kinetics showed a burst release until 2 days and after that sustained release pattern was showed. Therefore, these observations indicated that the formation of microsphere without the use of surfactant is feasible, and, this the improved process, the protein is readily incorporated in the microsphere.

• Macromolecular Research
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• 제15권7호
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• pp.623-632
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• 2007

Thermosensitive nanoparticles were prepared via the self-assembly of two different $poly({\varepsilon}-caprolactone)$-based block copolymers of poly(N-isopropylacrylamide)-b-$poly({\varepsilon}-caprolactone)$ (PNPCL) and poly(ethylene glycol)-b-$poly({\varepsilon}-caprolactone)$ (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using $^1H-NMR$, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants $(K_v)$ of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

• 폴리머
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• 제25권1호
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• pp.41-48
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• 2001

폴리카프로락톤디올(PCD) 및 폴리에틸렌글리콜(PEG), 디이소시아네이트 및 1,2,6-헥산트리올을 용액중합 방법으로 반응시켜 폴리우레탄(PU) 마이크로겔을 합성하였다. PCD/PEG의 몰비가 다른 마이크로겔의 임계 겔화농도의 성질과 생성에 영향을 주는 중요한 인자임을 알았다. 디이소시아네이트, PCD/PEG의 몰비 및 PEG의 분자량을 달리하여 제조한 PU 마이크로겔의 물리적 및 열적 성질을 실험하였다. PU 마이크로겔은 300nm 이하의 다분산성 구형의 작은 입자로 분포되어 있으며, 저점도 특성을 나타내었다.

• 분석과학
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• 제27권5호
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• pp.228-233
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• 2014

전기방사된 나노섬유는 구조 및 비교적 손쉬운 제조공정으로 의료용 재료분야의 활용이 늘어나고 있다. 제조된 나노섬유는 블럭공중합체의 PCL-PEG diamin block copolymer의 혼합 비가 높을수록 말단에 결합된 아민기의 비가 높아진다. 생분해성 고분자인 폴리카프로락톤(Poly(e-caprolactone,PCL)과 폴리카프로락톤-폴리에틸렌글리콜-아민(Poly(e-caprolactone)-Poly(ethylen glycol-$NH_2$))의 블럭공중합체를 혼합한 비율을 조절하여 전기방사법으로 방사함으로써, 세포와의 친화도를 조절하였다. PEG and amine의 비율과 콜라겐의 영향으로 손상된 세포의 성장을 촉진시키는 효과를 기대할 수 있는 생분해성 복합 나노섬유를 제작 및 특성 분석하였다.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.523-528
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• 2005

Diblock copolymers with different poly($\varepsilon$-caprolactone) (PCL) block lengths were synthesized by ringopening polymerization of $\varepsilon$-caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG-OH, MW 2000) as initiator. The self-aggregation behaviors of the diblock copolymer nanoparticle, prepared by the diafiltration method, were investigated by using $^1H$ NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG-PCL block copolymers formed the nano-sized self-aggregate in an aqueous environment by intrsa- and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations (cac) of the block copolymer self-aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The hydrodynamic diameters of the block copolymer nanoparticles, measured by DLS, were in the range of 65-270 nm. Furthermore, the size of the nanoparticles was scarcely affected by the concentration of the block copolymers in the range of 0.125-5 mg/mL owing to the negligible interparticular aggregation between the self-aggregated nanoparticles. Considered with the fairly low cac and nanoparticle stability, the PEG-PCL nanoparticles can be considered a potential candidate for biomedical applications such as drug carrier or imaging agent.

• 폴리머
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• 제28권4호
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• pp.344-351
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• 2004

온도에 반응하는 고분자로서 폴리(에틸렌 글리콜)을 기본으로 다이블록 및 트리블록 폴리에스테르 공중합체들은 비독성과 생체적합성 그러고 생분해성 특징 때문에 주사제형의 약물전달체로서 많은 응용이 이루어지고 있다. 본 연구에서는 다이블록 공중합체를 이용한 새로운 솔-젤 전이 현상을 갖는 고분자를 준비하고자, 평균분자량 750g/mole의 메톡시 폴리(에틸렌 글리콜)과 카프로락톤을 실온에서 HCI $.$ Et$_2$O 존재 하에서 개환중합을 실시하였다. 합성된 고분자는 시차주사열량계와 X-선 회절기를 이용하여 특성을 분석하였고, 수용액상에서의 고분자 용액은 실온에서 신체온도로 온도를 상승시키면 졸에서 겔 상으로의 상변화를 보였다. 신체온도 부근에서의 겔 형성을 확인하기 위하여 20 W% 졸 상태의 고분자용액을 쥐의 피하에 주입한 결과 분산 없이 겔이 잘 형성되었고 2개월 간 겔이 유지됨을 확인하였다. 이러한 연구 결과로, 새로운 솔-젤 상전이 현상을 보이는 다이블록 공중합체를 합성하였고, 주사형 이식 재료로의 가능성을 확인하였다.

• Macromolecular Research
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• 제17권2호
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• pp.72-78
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• 2009

Size control of therapeutic carriers in drug delivery systems has become important due to its relevance to biodistribution in the human body and therapeutic efficacy. To understand the dependence of particle size on the formation condition during nanoprecipitation method, we prepared nanoparticles from biodegradable, amphiphilic block copolymers and investigated the particle size and structure of the resultant nanoparticles according to various process parameters. We synthesized monomethoxy poly(ethylene glycol)-poly($\varepsilon$-caprolactone) block copolymer, MPEG-PCL, with different MPEG/PCL ratios via ring opening polymerization initiated from the hydroxyl end group of MPEG. Using various formulations with systematic change of the block ratio of MPEG and PCL, solvent choice, and concentration of organic phase, MPEG-PCL nanoparticles were prepared through nanoprecipitation technique. The results indicated that (i) the nanoparticles have a dual structure with an MPEG shell and a PCL core, originating from self-assembly of MPEG-PCL copolymer in aqueous condition, and (ii) the size of nanoparticles is dependent upon two sequential processes: diffusion between the organic and aqueous phases and solidification of the polymer.