Enzymatic degradation of block copolymers obtained by sequential ring opening polymerization of l-lactide and ɛ-caprolactone

Zhao, Zhenxian; Liu, Yang; Hu, Yanfei; He, Yong; Jia, Wei; Li, Suming

doi:10.1016/j.polymdegradstab.2007.07.012

Cited by 50 publications

(35 citation statements)

References 43 publications

(20 reference statements)

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“…On the other hand, the crystallization behavior of these two blocks is confined to each other, especially for the PCL segment at high T gel (≥4ºC). Li et al reported that the crystallization ability of the PCL segment in the PLLA-PCL-PLLA block copolymer reduced in the presence of PLLA block (Zhao et al, 2007). Combined with the thermal analyses results, it was clear that the knot-like structure and smooth pellicles protein adsorbed in NF scaffold were 2.8 and 3.2 times higher than those of the SW scaffold, respectively.…”

Section: Discussionmentioning

confidence: 95%

“…PCL is in a rubbery state at room temperature due to a low T g (glass transition temperature) and suffers a very slow degradation in vivo. Therefore, PLC or PGC might be promising materials for cartilage reconstruction because the incorporation of PCL could enhance the flexibility of the scaffold, and the degradation could be Nano-fibrous PCL-B-PLLA scaffolds modulated by changing the composition of the copolymer (Jeong et al, 2004;Zhao et al, 2007;Kister et al, 2000;Li et al, 1996). It was also documented that biodegradable polyurethanes based on the PCL and PLLA segments were alternative candidates for cartilage tissue engineering, and that they were degraded to nontoxic by-products in vivo (Gorna et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and properties of nano-fibrous PCL-b-PLLA scaffolds for cartilage tissue engineering

Liu²,

Guan³

et al. 2009

eCM

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Nano-fibrous scaffolds which could potentially mimic the architecture of extracellular matrix (ECM) have been considered a good candidate matrix for cell delivery in tissue engineering applications. In the present study, a semicrystalline diblock copolymer, poly(ε-caprolactone)-block-poly(L-lactide) (PCL-b-PLLA), was synthesized and utilized to fabricate nano-fibrous scaffolds via a thermally induced phase separation process. Uniform nano-fibrous networks were created by quenching a PCL-b-PLLA/THF homogenous solution to -20ºC or below, followed by further gelation for 2 hours due to the presence of PLLA and PCL microcrystals. However, knot-like structures as well as continuously smooth pellicles appeared among the nanofibrous network with increasing gelation temperature. DSC analysis indicated that the crystallization of PCL segments was interrupted by rigid PLLA segments, resulting in an amorphous phase at high gelation temperatures. Combining TIPS (thermally induced phase separation) with saltleaching methods, nano-fibrous architecture and interconnected pore structures (144±36 μm in diameter) with a high porosity were created for in vitro culture of chondrocytes. Specific surface area and protein adsorption on the surface of the nano-fibrous scaffold were three times higher than on the surface of the solid-walled scaffold. Chondrocytes cultured on the nano-fibrous scaffold exhibited a spherical condrocyte-like phenotype and secreted more cartilage-like extracellular matrix (ECM) than those cultured on the solid-walled scaffold. Moreover, the protein and DNA contents of cells cultured on the nanofibrous scaffold were 1.2-1.4 times higher than those on the solid-walled scaffold. Higher expression levels of collagen II and aggrecan mRNA were induced on the nanofibrous scaffold compared to on the solid-walled scaffold. These findings demonstrated that scaffolds with a nanofibrous architecture could serve as superior scaffolds for cartilage tissue engineering.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Microstructure and properties of nano-fibrous PCL-b-PLLA scaffolds for cartilage tissue engineering

Liu²,

Guan³

et al. 2009

eCM

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“…Because of this slow degradation property, such formulations may be promising in situ-forming gels for long-term biomedical applications. Several copolymeric systems containing PCL have been investigated for the potential to improve the slow degradation of native PCL [18][19][20]. Copolymers of PCL with PLLA have yielded materials with more rapid degradation rates.…”

Section: Discussionmentioning

confidence: 99%

A biodegradable, injectable, gel system based on MPEG-b-(PCL-ran-PLLA) diblock copolymers with an adjustable therapeutic window

et al. 2010

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“…New polymeric materials have been developed to provide a broad spectrum of applications such as regenerative surgery, drug delivery systems, orthopaedics and coronary stents, among others [1][2][3][4][5][6]. In this context, aliphatic polyesters such as poly(L-lactic acid) (PLLA), poly(glycolic acid) (PGA) or poly(-caprolactone) (PCL) have demonstrated to be useful for these applications [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Maglio et al investigated on PLLA-PCL-PLLA tri-block copolymers with high molecular weight and they concluded that the two blocks can be considered immiscible [24]. The degradation rate of PLLA-PCL copolymers has been reported by Zhao and col., who have developed materials with adjustable degradation time depending on the composition of the copolymer [5].…”

Section: Introductionmentioning

confidence: 99%

Effect of the molecular weight on the crystallinity of PCL-b-PLLA di-block copolymers

Peponi

Navarro-Baena

Báez

et al. 2012

Polymer

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A systematic study on the synthesis and characterization of di-block copolymers based on aliphatic polyesters such as poly(L-lactic acid) (PLLA) and poly(-caprolactone) (PCL), performed varying both the length of the blocks as well as the relative content of each block in the copolymers, is reported. The block-length and the molecular weight of each synthesized PCL-b-PLLA di-block copolymer were analyzed by nuclear magnetic resonance spectroscopy. The influence of the block length and of the amount of each block on the thermal properties and the morphology, was evaluated by differential scanning calorimetry and by small angle X-Ray scattering experiments. In particular, the correlation between the molecular weight of each block and its amorphous and/or crystalline structure was obtained, evidencing that the crystallization of the PLLA block was not influenced by the presence of PCL and depends mainly on its molecular weight but the crystallization of PCL is strongly interfered by the crystallization of PLLA. In particular PLLA blocks are amorphous for short lengths (≤ 672 g/mol, that means ≤ 9.3 LA repeat units) and start to crystallize for molecular weight ≥ 964 g/mol, that means ≥ 13.4 LA repeat units.

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Enzymatic degradation of block copolymers obtained by sequential ring opening polymerization of l-lactide and ɛ-caprolactone

Cited by 50 publications

References 43 publications

Microstructure and properties of nano-fibrous PCL-b-PLLA scaffolds for cartilage tissue engineering

Microstructure and properties of nano-fibrous PCL-b-PLLA scaffolds for cartilage tissue engineering

A biodegradable, injectable, gel system based on MPEG-b-(PCL-ran-PLLA) diblock copolymers with an adjustable therapeutic window

Effect of the molecular weight on the crystallinity of PCL-b-PLLA di-block copolymers

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