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Bi-layered PLCL/(PLGA/β-TCP) composite scaffold for osteochondral tissue engineering
Kim, Su Hee,Kim, Soo Hyun,Jung, Youngmee Technomic Pub. Co 2015 Journal of bioactive and compatible polymers Vol.30 No.2
<P>There have been many studies published on bi-layered osteochondral scaffolds that can induce tissue ingrowth for cartilage and bone. However, delivering different signals to each tissue effectively and enabling maturation into complex composite tissues remain challenging. In this study, an osteochondral composite scaffold was fabricated by combining a sintering method and a gel pressing method with poly(lactide-co-glycolide), beta-tricalcium phosphate, and poly(lactide-co-caprolactone). The composite scaffold constituted a poly(lactide-co-glycolide)/beta-tricalcium phosphate scaffold, which has osteoconduction activity for bone regeneration, and an elastic poly(lactide-co-caprolactone) scaffold, which has mechano-active properties for cartilage regeneration. To examine mechanical and biological properties, tensile tests, porosimetry, electron microscopy, and in vitro and in vivo experiments were performed. From the results, we confirmed that the scaffold had a homogeneously interconnected porous structure without a skin layer that exhibited exposed bioceramics onto the scaffold surface. Furthermore, it was shown that poly(lactide-co-glycolide)/beta-tricalcium phosphate of the osteochondral composite scaffold improved osteogenic differentiation and bone tissue formation. Also, chondrogenic differentiation of seeded cells was sustained on the highly elastic poly(lactide-co-caprolactone) of the osteochondral composite scaffold, and the amount of chondral extracellular matrix was increased significantly. Consequently, our osteochondral composite scaffolds may have the appropriate physiological and biological properties for regeneration of osteochondral composites.</P>
Crack prevention of biodegradable polymer coating on metal facilitated by a nano-coupled interlayer
Cho, Youngjin,Vu, Bach Quang,Bedair, Tarek M,Park, Bang Ju,Joung, Yoon Ki,Han, Dong Keun Technomic Pub. Co 2014 Journal of bioactive and compatible polymers Vol.29 No.5
<P>Crack prevention of biodegradable polymer coatings on drug-eluting stents was investigated by introducing a nano-coupled layer at the interface between the metal surface and the polymer coating layer using surface-initiated ring-opening polymerization of ε-caprolactone. Poly(<SMALL>d</SMALL>,<SMALL>l</SMALL>-lactide-co-glycolide) coating on cobalt-chromium control and ricinoleic acid-poly(caprolactone)–grafted cobalt-chromium was carried out using electrospraying. The cracking of the biodegradable polymer coating on drug-eluting stents during ballooning was addressed by introducing a nano-coupled interlayer on the cobalt-chromium surface. The ricinoleic acid-poly(caprolactone) nano-coupled interlayer and poly(<SMALL>d</SMALL>,<SMALL>l</SMALL>-lactide-co-glycolide)-coated top layer were characterized using attenuated total reflection Fourier transform infrared, contact angle, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. Based on scratch tests, the nano-coupled samples had stronger interfacial adhesion compared to the control sample without the nano-coupled layer. Scanning electron microscope images indicated that the cracking on the poly(<SMALL>d</SMALL>,<SMALL>l</SMALL>-lactide-co-glycolide) coating was addressed. Introducing a nano-coupling interlayer may be an important strategy to preventing polymer coating cracking on drug-eluting stents.</P>
A molecular zipping/unzipping nano-vehicles sensitive to tumor extracellular pH
Lee, Jung Ok,Lee, Min Ji,Kim, Dongin,Lee, Eun Seong Technomic Pub. Co 2014 Journal of bioactive and compatible polymers Vol.29 No.4
<P>A new class of pH-<I>responsive multivalent host</I>–guest interactions to manipulate polypeptide-based nano-vehicles was developed. Poly(<SMALL>l</SMALL>-lysine) (poly(Lys)) grafted with β-cyclodextrin and 2,3-dimethylmaleic acid was coupled with oleic acid. This new polymer was utilized to fabricate pH-responsive nano-vehicles for antitumor drug doxorubicin delivery. The host–guest (zipping) interaction between β-cyclodextrin and 2,3-dimethylmaleic acid moieties and the hydrophobic interaction between the oleic acid molecules contributed to form self-assembled nano-vehicles. 2,3-Dimethylmaleic acid moieties were highly degradable at a slightly acidic pH (~pH 6.8). These nano-vehicles increased the release of the encapsulated doxorubicin content (by the unzipping interaction between β-cyclodextrin and degraded 2,3-dimethylmaleic acid moieties) when the pH of the solution decreased to 6.8. This event caused a significant increase in the efficiency of cellular doxorubicin uptake and in vitro tumor inhibition.</P>
Perspectives On: Local and Sustained Delivery of Angiogenic Growth Factors
Lee, Hyukjin,Chung, Hyun Jung,Park, Tae Gwan Technomic Pub. Co 2007 Journal of bioactive and compatible polymers Vol.22 No.1
<P>This review emphasizes the role of angiogenesis in tissue engineering, introduces various angiogenic growth factors, and highlights current status of delivery systems for angiogenic growth factors using natural and synthetic biomaterials. A short overview of angiogenic growth factors is presented, followed by the introduction of emerging strategies for designing smart delivery carriers.</P>
Ryu, Tae-Kyung,Kim, Sung Eun,Kim, Joo-Hwan,Moon, Seung-Kwan,Choi, Sung-Wook Technomic Pub. Co 2014 Journal of bioactive and compatible polymers Vol.29 No.5
<P>Based on solid-in-oil-in-water emulsification, we fabricated biodegradable poly(ϵ-caprolactone) microspheres containing gentamicin using conventional homogenization and a fluidic device. The feasibility of the poly(ϵ-caprolactone) microspheres as drug carriers was evaluated in terms of encapsulation efficiency, release behavior of gentamicin, and antimicrobial activity. The poly(ϵ-caprolactone) microspheres prepared using a fluidic device (fluidic device microspheres) had a uniform diameter and a smooth surface, whereas the poly(ϵ-caprolactone) microspheres prepared using conventional homogenization (conventional homogenization microspheres) exhibited polydisperse and a porous structure. At 0.3 wt% of gentamicin concentration, the encapsulation efficiencies of the conventional homogenization and fluidic device microspheres were 39.5% and 72.0%, respectively. In addition, a significant amount of gentamicin was only released initially from the conventional homogenization microspheres, whereas the fluidic device microspheres released gentamicin in a sustained manner for 28 days. These results confirmed the superior performances of the uniform fluidic device microspheres for drug delivery system. We further proposed a model for microsphere formation to explain the difference in performance of the conventional homogenization and fluidic device microspheres.</P>
Lee, Minji,Lee, Dong Jin,Youn, Yu Seok,Lee, Eun Seong Technomic Pub. Co 2016 Journal of bioactive and compatible polymers Vol.31 No.2
<P>We report extremely small-sized drug-carrying globular poly(ethylene glycol) particles. These particles were prepared using fullerene (C-60) as a backbone structure and poly(ethylene glycol) as a hydrophilic shell. All - carbon bonds in C-60 were combined with poly(ethylene glycol), which form a globular nano-cage with a hollow core (originating from the soccer-ball-shaped truncated icosahedron of C-60) and the poly(ethylene glycol) shell. Subsequently, we constructed chlorin e6-conjugated globular poly(ethylene glycol). The obtained globular poly(ethylene glycol)-chlorin e6 (average 3.6nm in diameter) was soluble in aqueous solution and enabled improved singlet oxygen generation. The preferential cellular uptake of globular poly(ethylene glycol)-chlorin e6 resulted in significant enhancement of in vitro or in vivo photodynamic tumor cell ablation under light illumination. Our approach offers a versatile strategy to create extremely small-sized drug carriers using a biocompatible polymer for various biomedical applications.</P>