• Macromolecular Research
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• 제16권3호
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• pp.231-237
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• 2008

Biodegradable poly($\varepsilon$-caprolactone-co-L-lactide)-b-poly(ethylene glycol) (PCLA-b-PEG) copolymers were synthesized via solution polymerization by varying the feed composition of $\varepsilon$-caprolactone ($\varepsilon$-CL) and L-lactide (LLA) ($\varepsilon$-CL: LLA= 10:0, 7:3, 5:5, 3:7, 0: 10). The feed ratio based on weight is in accordance with the copolymer composition except for the case of $\varepsilon$-CL: LLA=3:7 (C3L7), which was verified by $^1H$-NMR. Two different approaches were used for the exceptional case, which is an extension of the reaction time or the sequential introduction of the monomer. A copolymer composition of $\varepsilon$-CL: LLA=3:7 could be obtained in either case. The chemical microstructure of PCLA-b-PEG was determined using the $^{13}C$-NMR spectra and the effect of the sequential structure on the thermal properties and crystallinity were examined. Despite the same composition ratio of the copolymer, the microstructure can differ according to the reaction conditions.

• Bulletin of the Korean Chemical Society
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• 제22권5호
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• pp.467-475
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• 2001

A triblock copolymer based on $poly(\varepsilon-caprolactone)$ (PCL) as the hydrophobic part and poly(ethylene glycol) (PEG) as the hydrophilic portion was synthesized by a ring-opening mechanism of ${\varepsilon}-caprolactone$ with PEG containing a hydroxyl group at bot h ends as an initiator. The synthesized block copolymers of PCL/PEG/PCL (CEC) were confirmed and characterized using various analysis equipment such as 1H NMR, DSC, FT-IR, and WAXD. Core-shell type nanoparticles of CEC triblock copolymers were prepared using a dialysis technique to estimate their potential as a colloidal drug carrier using a hydrophobic drug. From the results of particle size analysis and transmission electron microscopy, the particle size of CEC core-shell type nanoparticles was determined to be about 20-60 nm with a spherical shape. Since CEC block copolymer nanoparticles have a core-shell type micellar structure and small particle size similar to polymeric micelles, CEC block copolymer can self-associate at certain concentrations and the critical association concentration (CAC) was able to be determined by fluorescence probe techniques. The CAC values of the CEC block copolymers were dependent on the PCL block length. In addition, drug loading contents were dependent on the PCL block length: the larger the PCL block length, the higher the drug loading content. Drug release from CEC core-shell type nanoparticles showed an initial burst release for the first 12 hrs followed by pseudo-zero order release kinetics for 2 or 3 days. CEC-2 block copolymer core-shell type nanoparticles were degraded very slowly, suggesting that the drug release kinetics were governed by a diffusion mechanism rather than a degradation mechanism irrelevant to the CEC block copolymer composition.

• 폴리머
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• 제28권3호
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• pp.232-238
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• 2004

약물 전달체로서 메톡시 폴리(에틸렌 글리콜) (MPEG, methoxypolyethylene glycol)과 생분해성 폴리에스테르 계열의 카프로탁톤 ($\varepsilon$-CL, $\varepsilon$-caprolactone)으로 구성된 MPEG-PCL 블록 공중합체를 개환중합을 통해 합성하였다. MPEG-PCL의 결정성과 열적특성은 X선 굴절계와 시사주차열량계를 통하여 분석하였다 모델 단백질로서 알부민 (FITC-BSA, albumin bovine-fluorescein isothiocyanate)과 블록 공중합체를 동결 제분 후, 직접압축 성형방법에 의해 웨이퍼를 제조하였다. 알부민의 방출은 pH 7.4 인산염완충액을 사용하여 37$^{\circ}C$에서 14일 동안 관찰하였다. 알부민의 방출양은 형광분광기를 통하여 FITC의 강도에 의해 결정되었다. 웨이퍼의 형태학적 관찰은 디지털 카메라와 전자주사현미경을 통하여 관찰하였다. 알부민의 방출 속도와 초기 burst는 MPEG-PCL 블록 공중합체의 분절 내에서 폴리(에틸렌 글리롤)의 분자량이 증가할수록 또한 폴리카프로락톤의 분자량이 감소할수록 많은 초기방출과 단축된 방출기간을 보였다.

• 폴리머
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• 제33권3호
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• pp.248-253
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• 2009

의료용으로 적용될 수 있는 새로운 재료를 제조하기 위하여 폴리카프로락톤(PCL)과 양친성 구조를 갖는 폴리(에틸렌 글리콜)(PEG)이 그래프트된 PCL을 이용하여 생분해성 블렌드를 제조하였다. 제조된 블렌드는 PCL을 기본으로 하고 여기에 그래프트 공중합체의 함량을 변화시키며 열적 그리고 결정화 특성을 관찰하였다. 그래프트 공중합체의 함량 변화에 따라 결정화 온도의 변화 및 결정화 속도가 변화하였고 이를 통해 그래프트 공중합체가 PCL의 결정화 거동에 영향을 미침을 확인하였다. 이는 광학현미경을 통한 결정의 교대 소광 밴드의 관찰을 통하여서도 확인할 수 있었다. 약물방출시스템과 같은 의료용 응용을 고려하여 블렌드 필름의 흡수거동과 단백질 흡착에 대한 특성도 평가하였다.

• Archives of Pharmacal Research
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• 제18권1호
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• pp.18-21
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• 1995

Poly(ethylene glycol)(PEG) macrocers teminated with acrylate groups and semi-interpenetrating polymer networks (IPNs) composed of poly-.epsilon.-capolactone(PCL) and PEG macromer were syntheswized with the aim of obtaining a bioerodible hydrogel that could be used to release drugs for implantable delivery system. Polymerization of PEG macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Non-crosslinked PCL chains were interpenetrated into the cross-linked three-dimensions networks of PEG. The IPNs, largw drug loading lower concentration of PEG macromer in the IPNs concentration and the higher molecular weight of PEG macromer. Also, 5-FU was more fast released than hydrocortisone to the increased water solubility.

• 대한의용생체공학회:의공학회지
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• 제40권1호
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• pp.7-14
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• 2019

The microencapsulation of nifedipine (NF) with 4 wt% of poly(${\varepsilon}-caprolactone$) (PCL)/polyvinylpyrollidone (PVP) or PCL/polyethylene glycol (PEG) was carried out by solvent evaporation method in oil in water emulsion system to investigate the effect of PVP and PEG addition on drug release behavior of the microcapsules. The PVA (emulsifier) concentration of 1.0 wt% was chosen for the formation of PCL capsule having an average size of $154{\pm}25{\mu}m$ due to nearly spherical shape with a narrow size distribution. As PCL/PVP and PCL/PEG ratios were raised from 10/0 to 6/4, the capsule size increased gradually from $154{\pm}25{\mu}m$ to $236{\pm}32{\mu}m$ and $248{\pm}56{\mu}m$, respectively. The drug release rate of PCL/PVP and PCL/PEG capsules increased dramatically from 0 to 4 h at the beginning and then reached the plateau region from 20 h. As the concentration of PVP or PEG increased, the amount of drug release increased, suggesting that the larger capsule size was attributed to the higher drug content. However, the drug release behavior remained almost constant. The PCL capsules exhibited no evidence of causing cell lysis or toxicity regardless of NF loading, implying that the microcapsules are clinically suitable for use as drug delivery systems.

• Fibers and Polymers
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• 제3권4호
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• pp.153-158
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• 2002

A series of waterborne polyurethanes (WBPU) were prepared from 4,4-dicyclohexylmethane diisocyanate ($H_{12}$MDI),2,2-bis(hydroxylmethyl) propionic acid (DMPA), othylenediarnine (EDA), triethylamine (TEA), and triblock glycol [TBG, ($\varepsilon$-caprolactone)$_{4.5}$-poly(tetramethylene ether) glycol (MW= 2000)-($\varepsilon$-caprolactone)$_{4.5}$: $(CL)_{4.5}$-PTMG-$(CL)_{4.5}$, MW=3000] as a soft segment. Two melting peaks of TBG at about 14$^{\circ}C$ and 38$^{\circ}C$ were observed indicating the presence of two different crystalline domains composed of CL and PTMG dominant component. The effect of soft segment content (60-75 wt%) on the colloidal properties of dispersion, and thermal and mechanical properties of WBPU films, the water vapor permeability (WVP) and water resistance (WR) of WBPU-coated Nylon fabrics, and the adhesive strength of WBPU- coated layer and Nylon fabrics was investigated. As soft segment contents increased, the water vapor permeability of WBPU- coated Nylon fabrics increased from 3615 to 4502 g/$m^2$day, however, the water resistances decreased from 1300 to 500 mm$H_2$O.O.

• Tissue Engineering and Regenerative Medicine
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• 제15권6호
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• pp.735-750
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• 2018

BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica ($n-SiO_2$) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and $n-SiO_2$ incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190-260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with $n-SiO_2$. While the hydrophilicity of $n-SiO_2$ incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to $n-SiO_2$ incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and $n-SiO_2$. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.

• Macromolecular Research
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• 제14권1호
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• pp.45-51
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• 2006

We conducted simultaneous, small-angle, X-ray scattering/differential scanning calorimetry (SAXS/DSC) and simultaneous, wide-angle, X-ray scattering (WAXS)/DSC measurements for a polymer blend of poly($\varepsilon$-caprolactone)/poly(ethylene glycol)(PCL/PEG). The time-dependent SAXS/DSC and WAXS/DSC results, measured while the system was quenched below the melting temperature of PCL from a melting state, revealed the competitive behavior between liquid-liquid phase separation and crystallization in the polymer blend. The time-dependent structural evolution extracted from the SAXS/WAXS/DSC results can be characterized by the following four stages in the PCL crystallization process: the induction (I), nucleation (II), growth (III), and late (IV) stages. The influence of the liquid-liquid phase separation on the crystallization of PCL was also observed by phase-contrast microscope and polarized microscope with 1/4$\lambda$ compensator.

• Macromolecular Research
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• 제14권1호
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• pp.117-120
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• 2006