• Polymer(Korea)
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• v.32 no.5
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• pp.458-464
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• 2008

A successful scaffold should have a highly porous structure and good mechanical stability. High porosity and appropriate pore size provide structural matrix for initial cell attachment and proliferation enabling the exchange of nutrients between the scaffold and environment. In this paper the highly porous scaffold of poly(${\varepsilon}$-caprolactone) electrospun nanofibers could be manufactured with an auxiliary electrode and chemical blowing agent (BA) under several processing conditions, such as the concentration of PCL solution, weight percent of a chemical blowing agent, and decomposition time of a chemical blowing agent. To attain stable electrospinnability and blown nanofiber mats having high microporosity and large pore, a processing condition, 8wt% of PCL solution and 0.5wt% of a chemical blowing agent under $100^{\circ}C$ and decomposition time of $2{\sim}3\;s$, was used. The growth characteristic of human dermal fibroblasts cells cultured in the mats showed the good adhesion and proliferation on the blown mat compared to a normal electrospun mat.

• Journal of Periodontal and Implant Science
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• v.53 no.3
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• pp.218-232
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• 2023

Purpose: This study evaluated the efficacy of a tube-shaped poly(ε) caprolactone - β tricalcium phosphate (PCL-TCP) scaffold with the incorporation of human umbilical cord-derived mesenchymal stem cells (hUCMSCs) and platelet-rich plasma (PRP) for bone regeneration in the procedure of single-stage sinus augmentation and dental implantation in minipigs. Methods: Implants were placed in the bilateral sides of the maxillary sinuses of 5 minipigs and allocated to a PCL-TCP+hUCMSCs+PRP group (n=5), a PCL-TCP+PRP group (n=5), and a PCL-TCP-only group (n=6). After 12 weeks, bone regeneration was evaluated with soft X-rays, micro-computed tomography, fluorescence microscopy, and histomorphometric analysis. Results: Four implants failed (2 each in the PCL-TCP+hUCMSCs+PRP and PCLTCP+hUCMSC groups). An analysis of the grayscale levels and bone-implant contact ratio showed significantly higher mean values in the PCL-TCP+hUCMSCs+PRP than in the PCL-TCP group (P=0.045 and P=0.016, respectively). In fluoromicroscopic images, new bone formation around the outer surfaces of the scaffolds was observed in the PCLTCP+hUCMSCs+PRP group, suggesting a tenting effect of the specially designed scaffolds. Bone regeneration at the scaffold-implant interfaces was observed in all 3 groups. Conclusions: Using a tube-shaped, honeycombed PCL-TCP scaffold with hUCMSCs and PRP may serve to enhance bone formation and dental implants' osseointegration in the procedure of simultaneous sinus lifting and dental implantation.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.149-159
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• 2007

In order to prepare high-solid coatings, acrylic resins, HSCs [poly (EA/EMA/2-HEMA/CLA)] that contain 90% solid, were synthesized by copolymerization of ethyl acrylate (EA), ethyl methacrylate (EMA), 2-hydroxyethyl methacrylate (2-HEMA) and caprolactone acrylate (CLA). The high-solid coatings named as CHSCs (HSCs/HDI-trimer) were prepared by the curing reaction between the acrylic resins containing 90% solid contents and the isocyanates (HDI-trimer) curing agent room temperature. The curing behavior and various properties were examined on the film coated with the both high-solid coatings. The glass transition temperatures $(T_g)$ of CHSCs increased proportionally with increasing the predicted $T_g$ value by Fox equation, and had nothing to do with the solid contents. The prepared film showed good properties for $60^{\circ}$ specular gloss, impact resistance, cross-hatch adhesion and heat resistance, and bad properties for pencil hardness, drying time, and pot-life. Among the film properties, the heat resistance was very excellent and could be explained by the introduction of functional monomers of CLA.

• Fibers and Polymers
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• v.3 no.4
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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.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.757-767
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• 1996

Poly(alkyl acrylate-g-caprolactone) graft copolymers were prepared, and they were applied as compatibilizing agents for polycarbonate (PC) / poly(acrylonitrile-butadiene-styrene) (ABS) blends. The incompatible poly(alkyl acrylate) segment was incorporated into the graft copolymer in order to localize the copolymer at the PC/ABS interface. The blend containing 1 phr of the copolymer showed remarkable improvement in impact strength as well as in elongation at break. Impact improvement was more pronounced with a thinner test specimens of 1/8 inch thickness. Morphological study showed that the presence of the graft copolymer led to a smoother PC/ABS interface due to the interfacial enrichment of the graft copolymer.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.28-36
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• 2011

Diblock copolymers composed of poly(${\varepsilon}$-caprolactone) (PCL) and poly(N,N-dimethylamino-2-ethyl methacrylate) (PDMAEMA), or methoxy polyethylene glycol(PEG), were synthesized via a combination of ring-opening polymerization and atom-transfer radical polymerization in order to prepare polymeric nanoparticles as an antifungal drug carrier. Amphotericin B (AmB), a natural antibiotic, was incorporated into the polymeric nanoparticles. The physical properties of AmB-incorporated polymeric nanoparticles with PCL-b-PDMAEMA and PCL-b-PEG were studied in relation to morphology and particle size. In the aggregation state study, AmB-incorporated PCL-b- PDMAEMA nanoparticles exhibited a monomeric state pattern of free AmB, whereas AmB-incorporated PCL-b- PEG nanoparticles displayed an aggregated pattern. In in vitro hemolysis tests with human red blood cells, AmBincorporated PCL-b-PDMAEMA nanoparticles were seen to be 10 times less cytotoxic than free AmB (5 ${\mu}g$/ml). In addition, an improved antifungal activity of AmBincorporated polymeric nanoparticles was observed through antifungal activity tests using Candida albicans, whereas polymeric nanoparticles themselves were seen not to affect activity. Finally, in vitro AmB release studies were conducted, proving the potential of AmB-incorporated PCL-b-PDMAEMA nanoparticles as a new formulation candidate for AmB.

• Journal of Chest Surgery
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• v.41 no.2
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• pp.160-169
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• 2008

Bakcground: To treat anastomosis site stenosis and occlusion of the artificial vessels used in vascular surgery, tissue-engineered artificial vessels using autologous cells have been constructed. We developed artificial vessels using a polymer scaffold and autologous bone marrow cells and performed an in vivo evaluation. Material and Method: We manufactured a vascular scaffold using biodegradable PLCL (poly lactide-co-${\varepsilon}$-caprolactone) and PGA (poly glycolic acid) fibers. Then we seeded autologous bone marrow cells onto the scaffold. After implantation of the artificial vessel into the abdominal aorta, we performed an angiography 3 weeks after surgery. After the dogs were euthanized we retrieved the artificial vessels and performed histological analysis. Result: Among the six dogs, 2 dogs died of massive bleeding due to a crack in the vascular scaffold 10 days after the operation. The remaining four dogs lived for 3 weeks after the operation. In these dogs. the angiography revealed no stenosis or occlusion at 3 weeks after the operation. Gross examination revealed small thrombi on the inner surface of the vessels and the histological analysis showed three layers of vessel structure similar to the native vessel. Immunohistochemical analysis demonstrated regeneration of the endothelial and smooth muscle cell layers. Conclusion: A tissue engineered vascular graft was manufactured using a polymer scaffold and autologous bone marrow cells that had a structure similar to that of the native artery. Further research is needed to determine how to accommodate the aortic pressure.

• Polymer(Korea)
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• v.36 no.4
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• pp.420-426
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• 2012

In this study, we prepared polymer micelles containing quercetin and rutin, known as antioxidants, using poly(${\varepsilon}$-caprolactone)-b-poly(ethylene glycol), and evaluated in vitro skin permeation of the active materials. Quercetin and rutin loaded micelles were characterized by DSC (differential scanning calorimetry), HPLC (high performance liquid chromatography) and DLS (dynamic light scattering) measurements. The particle size of the polymer micelles increased in a concentration dependent manner (0.5~2.0% PCL-b-PEG). The Zeta potential of quercetin and rutin loaded micelles remained constant. To evaluate the skin penetration of PCL-b-PEG micelles, Franz diffusion cell experiment was performed. The aqueous solutions of quercetin and rutin were used as the control groups. Quercetin and rutin loaded PCL-b-PEG micelles showed more efficient skin permeation than the control groups. Safety assessment (patch test) of quercetin and rutin loaded PCL-b-PEG micelles on skin was performed to test application possibility of the polymer micelles to cosmetics. Any adverse symptoms were not observed.

• Polymer(Korea)
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• v.28 no.3
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• pp.211-217
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• 2004

The sol to gel transition of aqueous solution of block copolymers consisting of methoxy poly (ethylene glycol) (MPEG) and biodegradable polyesters such as $\varepsilon$-caprolactone and L-lactide was investigated as a function of temperature. MPEG-PCL was prepared by ring opening polymerization of $\varepsilon$-caprolactone in the presence of HClㆍEt$_2$O as monomer activator at room temperature. Also, MPEG-PLLA was prepared by ring opening polymerization of L-lactide in the presence of stannous octoate at 115$^{\circ}C$. The properties of block copolymers were investigated by $^1$H-NMR, IR, and GPC as well as the observation of thermo sensitive phase transition in aqueous solution. As the hydrophobic block length increased, the sol to gel transition temperature increased and curve of that steepen to lower concentration. To confirm the gel formation at body temperature, we observed the formation of gel in the mice body after injection of 20 wt% aqueous solution of each block copolymer. After surging, we investigated the gelation in mice. The results obtained in this study confirmed the feasibility as biomaterials of injectable implantation for controlled release of drug and protein delivery.

• Polymer(Korea)
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• v.34 no.6
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• pp.507-510
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• 2010

Poly(cyclohexane carbonate) diol was synthesized by the alternating copolymerization of cyclohexene oxide and $CO_2$ over Cr based transition metal catalysts. The prepared PCCD was applied as a precursor for the preparation of waterborne polyurethane (PUD) in order to investigate an application field of carbon dioxide-based polycarbonate. The scratch resistance and thermal properties of PUDs, which was prepared with two kinds of polymeric diols (PCD and PCCD) were investigated. The scratch resistance and thermal decomposition temperature of PUD film prepared with PCCD is worse than those prepared with PCD, poly(hexamethylene carbonate) glycol. While, glass transition temperature of PUD film prepared with PCCD was higher than that prepared with PCD. It might be due to the rigid cyclohexane structure in the PCCD.