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Yoshiharu Doi - One of the best experts on this subject based on the ideXlab platform.
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Surface properties and Enzymatic Degradation of end-capped poly(l-lactide)
Polymer Degradation and Stability, 2006Co-Authors: Kenji Kurokawa, Yoshiharu Doi, Koichi Yamashita, Hideki AbeAbstract:Abstract Surface properties and Enzymatic Degradation of poly( l -lactide) (PLLA) end-capped with hydrophobic dodecyl and dodecanoyl groups were investigated by means of advancing contact angle ( θ a ) measurement, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The θ a values of end-capped PLLA films were larger than those of non-end-capped PLLA films, suggesting that the hydrophobic dodecyl and dodecanoyl groups were segregated on the film surface. The weight changes of end-capped PLLA thin films during Enzymatic Degradation in the presence of proteinase K were monitored by using a QCM technique. The relatively fast weight loss of PLLA film occurred during first few hours of Degradation, followed by a decrease in the erosion rate. The erosion rate of PLLA films at the initial stage of Degradation was dependent on the chain-end structure of PLLA molecules, and the value decreased with an increase in the amount of hydrophobic functional groups. The surface morphologies of PLLA thin films before and after Degradation were characterized by AFM. After the Enzymatic Degradation, the surface of non-end-capped PLLA films was blemished homogeneously. In contrast, the end-capped PLLA thin films were degraded heterogeneously by the enzyme, and many hollows were formed on the film surface. From these results, it has been concluded that the introduction of hydrophobic functional groups at the chain-ends of PLLA molecules depressed the erosion rate at the initial stage of Enzymatic Degradation.
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Effect of monomer composition and composition distribution on Enzymatic Degradation of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)
Macromolecular Chemistry and Physics, 1999Co-Authors: Naoko Yoshie, Yoshiharu Doi, Ken-ichi Kasuya, Hideki Abe, Mikiko Fujiwara, Yoshio InoueAbstract:The Enzymatic Degradation of solution-cast films of bacterial poly(3-hydroxybutyrate) [PHB] and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-co-HV)] with various comonomer compositions and with various composition distributions was investigated by using PHB depolymerase purified from Alcaligenes faecalis T1. We prepared P(HB-co-HV) samples with different composition distribution by fractional precipitation of P(HB-co-HV). The rate of Enzymatic Degradation of the P(HB-co-HV) samples showed a linear increase with the HV content up to about 30 mol-%. Although the crystalline phase structure of the P(HB-co-HV)s changes depending on the composition distribution, their Enzymatic degradability is independent of the composition distribution. The comonomer composition distribution and the crystalline phase structure have little effect on the rate of Enzymatic Degradation. The rate of Enzymatic Degradation of P(HB-co-HV) can be predicted on the basis of its average monomer composition.
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Enzymatic Degradation of microbial poly(3-hydroxyalkanoates)
Polymer Degradation and Stability, 1994Co-Authors: Youko Kanesawa, Yoshiharu Doi, Naoki Tanahashi, Terumi SaitoAbstract:Abstract The microbial copolyesters incorporating 3-hydroxyalkanoate units with different chain lengths (C4–C10) were produced from various carbon substrates by Alcaligenes eutrophus or Pseudomonas oleovorans . The Enzymatic Degradation processes of the poly(3-hydroxyalkanoates) (PHA) films were studied at 37°C in a phosphate buffer (pH 7·4) containing the PHA depolymerase from A. faecalis T1 . The rate of Enzymatic Degradation was determined by monitoring the time-dependent changes in weight loss(erosion) of polyester films. The rate was strongly dependent upon the composition of the polyesters and markedly decreased with an increase in the side-chain length of the 3-hydroxyalkanoate monomeric units. The polyester chains were finally degraded into the monomers and dimers of 3-hydroxyalkanoic acids by the PHA depolymerase.
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Enzymatic Degradation of microbial poly(3‐hydroxybutyrate) films
Die Makromolekulare Chemie, 1992Co-Authors: Yoshiharu Kumagai, Youko Kanesawa, Yoshiharu DoiAbstract:The effects of crystallinity and spherulite size on the Enzymatic Degradation of microbial poly(3-hydroxybutyrate) (PHB) films have been studied at 37°C and pH 7,4 in aqueous solutions of an extracellular PHB depolymerase from Alcaligenes faecalis T1. The rate of Enzymatic Degradation of PHB films decreases with an increase in crystallinity, but it is little influenced by the size of PHB spherulites. It was suggested that the PHB depolymerase firstly hydrolyzes the PHB chains in the amorphous state on the surface of the films and subsequently erodes the PHB chains in the crystalline state.
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Enzymatic Degradation of binary blends of microbial poly(3-hydroxybutyrate) with Enzymatically active polymers
Polymer Degradation and Stability, 1992Co-Authors: Yoshiharu Kumagai, Yoshiharu DoiAbstract:The miscibility and biodegradability of binary blends of microbial poly(3-hydroxybutyrate) (PHB) with poly(β-propiolactone) (PPL), poly(ethylene adipate) (PEA) and microbial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV, HB 24 mol% and HV 76 mol%) have been studied by analysis of differential scanning calorimetry (DSC), scanning electron micrography (SEM) and Enzymatic Degradation. The glass transition temperature (Tg) data indicated that the blends of PHB/PPL, PHB/PEA and PHB/PHB-HV were immiscible in the amorphous state. The Enzymatic Degradation of the PHB-based blend films was carried out at 37°C and pH 7·4 in an aqueous solution of an extracellular PHB depolymerase from Alcaligenes faecalis T1. The films of PPL, PEA and PHB-HV polymers, as well as the films of PHB, were degraded by the PHB depolymerase. The rates of Enzymatic Degradation of the PHB/PPL, PHB/PEA and PHB/PHB-HV blend films were higher than the rate of each polymer component film. In the SEMs of the surface and cross-section of a PHB/PPL (26:74, w/w) film, large holes, 10–30 μm in diameter, were detected not only on the surface but also inside the film. The acceleration of Enzymatic Degradation of the blend films may be caused by an increase in the surface area of film active to the PHB depolymerase.
Xiabin Jing - One of the best experts on this subject based on the ideXlab platform.
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Enzymatic Degradation of poly l lactide and poly e caprolactone electrospun fibers
Macromolecular Bioscience, 2004Co-Authors: Jing Zeng, Qizhi Liang, Xuesi Chen, Xiabin JingAbstract:Poly(L-lactide) (PLLA) and poly(e-caprolactone) (PCL) ultrafine fibers were prepared by electrospinning. The influence of cationic and anionic surfactants on their Enzymatic Degradation behavior was investigated by measuring weight loss, molecular weight, crystallinity, and melting temperature of the fibers as a function of Degradation time. Under the catalysis of proteinase K, the PLLA fibers containing the anionic surfactant sodium docecyl sulfate (SDS) exhibited a faster Degradation rate than those containing cationic surfactant triethylbenzylammonium chloride (TEBAC), indicating that surface electric charge on the fibers is a critical factor for an Enzymatic Degradation. Similarly, TEBAC-containing PCL fibers exhibited a 47% weight loss within 8.5 h whereas SDS-containing PCL fibers showed little Degradation in the presence of lipase PS. By analyzing the charge status of proteinase K and lipase PS under the experimental conditions, the importance of the surface charges of the fibers and their interactions with the charges on the enzymes were revealed. Consequently, a two-step Degradation mechanism was proposed: (1) the enzyme approaches the fiber surface; (2) the enzyme initiates hydrolysis of the polymer. By means of differential scanning calorimetry and wide-angle X-ray diffraction, the crystallinity and orientation changes in the PLLA and PCL fibers during the Enzymatic Degradation were investigated, respectively.
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Enzymatic Degradation of poly e caprolactone poly dl lactide blends in phosphate buffer solution
Polymer, 1999Co-Authors: Zhihua Gan, Zhiyuan Zhong, Qizhi Liang, Xiabin JingAbstract:Abstract Blend films of poly(e-caprolactone) (PCL) and poly( dl -lactide) (PDLLA) with 0.5 weight fraction of PCL were prepared by means of solution casting and their Degradation behavior was studied in phosphate buffer solution containing Pseudomonas (PS) lipase. Enzymatic Degradation of the blend films occurred continuously within the first 6 days and finally stopped when the film weight loss reached 50%, showing that only PCL in the blends degraded under the action of PS lipase in the buffer solution. These results indicate the selectivity of PS lipase on the promotion of Degradation for PCL and PDLLA. The thermal properties and morphology of the blend films were investigated by differential scanning calorimetry, wide-angle X-ray diffraction and scanning electron microscopy (SEM). The morphology resulting from aggregate structures of PCL in the blends was destroyed in the Enzymatic Degradation process, as observed by SEM. These results confirm again the Enzymatic Degradation of PCL in the blends in the presence of PS lipase.
Ana Vidaurre - One of the best experts on this subject based on the ideXlab platform.
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Production and Enzymatic Degradation of poly(ε-caprolactone)/graphene oxide composites
Materials Express, 2020Co-Authors: V. Martínez-ramón, I. Castilla-cortázar, Ana Vidaurre, Alberto J. Campillo-fernándezAbstract:Poly(ε-caprolactone) (PCL) based composites containing different graphene oxide (GO) contents (0.1, 0.2 and 0.5 wt%) were produced by the solution mixing method followed by compression molding and Enzymatically degraded in a pH 7.4 phosphate buffer solution containing Pseudomonas lipase at 37 °C. Morphological changes, molecular weight, calorimetric and mechanical properties were analyzed according to graphene oxide content. The study of tensile properties showed that the composites increased their Young’s modulus, while tensile strength and elongation at break decreased to significantly less than that of neat PCL. PCL composite crystallinity was evaluated by differential scanning calorimetry (DSC). It was found that incorporating GO can reduce nucleation activity as well as crystallization rates, from 67.6% for neat PCL to 50.6% for a composite with 0.5 wt% GO content. For Enzymatic Degradation, the weight loss data showed that incorporating GO into the PCL significantly altered Enzymatic Degradation. The presence of GO did not alter PCL’s hydrolysis mechanism, but did slow down composite Enzymatic Degradation in proportion to the percentage of filler content.
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hydrolytic and Enzymatic Degradation of a poly e caprolactone network
Polymer Degradation and Stability, 2012Co-Authors: I Castillacortazar, Ana Vidaurre, J. L. Escobar Ivirico, Bernabé Marí, J Masestelles, J M MeseguerduenasAbstract:Abstract Long-term hydrolytic and Enzymatic Degradation profiles of poly(e-caprolactone) (PCL) networks were obtained. The hydrolytic Degradation studies were performed in water and phosphate buffer solution (PBS) for 65 weeks. In this case, the Degradation rate of PCL networks was faster than previous results in the literature on linear PCL, reaching a weight loss of around 20% in 60 weeks after immersing the samples either in water or in PBS conditions. The Enzymatic Degradation rate in Pseudomonas Lipase for 14 weeks was also studied, with the conclusion that the Degradation profile of PCL networks is lower than for linear PCL, also reaching a 20% weight loss. The weight lost, degree of swelling, and calorimetric and mechanical properties were obtained as a function of Degradation time. Furthermore, the morphological changes in the samples were studied carefully through electron microscopy and crystal size through X-ray diffraction. The changes in some properties over the Degradation period such as crystallinity, crystal size and Young's modulus were smaller in the case of Enzymatic studies, highlighting differences in the Degradation mechanism in the two studies, hydrolytic and Enzymatic.
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Hydrolytic and Enzymatic Degradation of a poly(ε-caprolactone) network
Polymer Degradation and Stability, 2012Co-Authors: I. Castilla-cortázar, J. Más-estellés, J. M. Meseguer-dueñas, J. L. Escobar Ivirico, Bernabé Marí, Ana VidaurreAbstract:Abstract Long-term hydrolytic and Enzymatic Degradation profiles of poly(e-caprolactone) (PCL) networks were obtained. The hydrolytic Degradation studies were performed in water and phosphate buffer solution (PBS) for 65 weeks. In this case, the Degradation rate of PCL networks was faster than previous results in the literature on linear PCL, reaching a weight loss of around 20% in 60 weeks after immersing the samples either in water or in PBS conditions. The Enzymatic Degradation rate in Pseudomonas Lipase for 14 weeks was also studied, with the conclusion that the Degradation profile of PCL networks is lower than for linear PCL, also reaching a 20% weight loss. The weight lost, degree of swelling, and calorimetric and mechanical properties were obtained as a function of Degradation time. Furthermore, the morphological changes in the samples were studied carefully through electron microscopy and crystal size through X-ray diffraction. The changes in some properties over the Degradation period such as crystallinity, crystal size and Young's modulus were smaller in the case of Enzymatic studies, highlighting differences in the Degradation mechanism in the two studies, hydrolytic and Enzymatic.
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Influence of Enzymatic Degradation on Physical Properties of Poly(ε‐caprolactone) Films and Sponges
Macromolecular Symposia, 2008Co-Authors: Ana Vidaurre, José María Meseguer Dueñas, Jorge Más Estellés, Isabel Castilla CortázarAbstract:The effect of Enzymatic Degradation on poly(e-caprolactone) (PCL) films and sponges was investigated at 37 °C using Pseudomonas lipase. Film samples were prepared by the solution casting method, while sponges were obtained by the freeze extraction method. The porosity was 17 and 60% respectively. Weight loss, morphology, crystallinity and mechanical properties were studied. The kinetic study on the Enzymatic Degradation of PCL porous samples depends on porosity, suggesting that Degradation took place on the surface, not suffering bulk Degradation. The non-dependence on crystallinity indicates that Degradation occurred in both phases, amorphous and crystalline, at the same time.
Qizhi Chen - One of the best experts on this subject based on the ideXlab platform.
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A comparative study on in vitro Enzymatic Degradation of poly(glycerol sebacate) and poly(xylitol sebacate)
RSC Advances, 2012Co-Authors: Qizhi Chen, Xueyuan YangAbstract:Poly(glycerol sebacate) (PGS) is a soft elastomer suitable for tissue engineering of soft types. However, the rapid Degradation kinetics of this polyester has become one of the major drawbacks in the application of tissue engineering. In this work, a comparative study on in vitro Enzymatic Degradation of PGS- and poly(xylitol sebacate) (PXS)-based materials has been conducted, using a recently established in vitro experimental protocol. This protocol, which can simulate and predict in vivo Enzymatic Degradation kinetics of polymer implants, was further refined in this work. The comparative study was conducted in tissue culture medium and a buffer solution of pH optima, under static and cyclic mechanical loading conditions. It was found that in vitro Enzymatic Degradation rates of the PXS-based materials were significantly slower than those of PGS in both the tissue culture medium and buffered solution of pH optima (pH 8). The in vitro Enzymatic Degradation of PGS-based biomaterials tested was about 0.1–0.4 mm month−1 in tissue culture medium, while the rates were in the range of 0.05–0.2 mm month−1 for PXS-based materials. Enzymatic Degradation was enhanced in relation to mechanical deformation, whereas PXS-based materials were influenced little. Hence, PXS, which is as soft as PGS but degrades significantly slower than PGS, is a better option for applications in tissue engineering of soft types.
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In Vitro Enzymatic Degradation of poly (glycerol sebacate)-based materials
Biomaterials, 2011Co-Authors: Shuling Liang, Xueyuan Yang, Xi-ya Fang, Wayne D. Cook, George Anthony Thouas, Qizhi ChenAbstract:Abstract Enzymatic Degradation is a major feature of polyester implants in vivo . An in vitro experimental protocol that can simulate and predict the in vivo Enzymatic Degradation kinetics of implants is of importance not only to our understanding of the scientific issue, but also to the well-being of animals. In this study, we explored the Enzymatic Degradation of PGS-based materials in vitro , in tissue culture medium or a buffer solution at the pH optima and under static or cyclic mechanical-loading conditions, in the presence of defined concentrations of an esterase. Surprisingly, it was found that the in vitro Enzymatic Degradation rates of the PGS-based materials were higher in the tissue culture medium than in the buffered solution at the optimum pH 8. The in vitro Enzymatic Degradation rate of PGS-based biomaterials crosslinked at 125 °C for 2 days was approximately 0.6–0.9 mm/month in tissue culture medium, which falls within the range of in vivo Degradation rates (0.2–1.5 mm/month) of PGS crosslinked at similar conditions. Enzymatic Degradation was also further enhanced in relation to mechanical deformation. Hence, in vitro Enzymatic Degradation of PGS materials conducted in tissue culture medium under appropriate Enzymatic conditions can quantitatively capture the features of in vivo Degradation of PGS-based materials and can be used to indicate effective strategies for tuning the Degradation rates of this material system prior to animal model testing.
Xueyuan Yang - One of the best experts on this subject based on the ideXlab platform.
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A comparative study on in vitro Enzymatic Degradation of poly(glycerol sebacate) and poly(xylitol sebacate)
RSC Advances, 2012Co-Authors: Qizhi Chen, Xueyuan YangAbstract:Poly(glycerol sebacate) (PGS) is a soft elastomer suitable for tissue engineering of soft types. However, the rapid Degradation kinetics of this polyester has become one of the major drawbacks in the application of tissue engineering. In this work, a comparative study on in vitro Enzymatic Degradation of PGS- and poly(xylitol sebacate) (PXS)-based materials has been conducted, using a recently established in vitro experimental protocol. This protocol, which can simulate and predict in vivo Enzymatic Degradation kinetics of polymer implants, was further refined in this work. The comparative study was conducted in tissue culture medium and a buffer solution of pH optima, under static and cyclic mechanical loading conditions. It was found that in vitro Enzymatic Degradation rates of the PXS-based materials were significantly slower than those of PGS in both the tissue culture medium and buffered solution of pH optima (pH 8). The in vitro Enzymatic Degradation of PGS-based biomaterials tested was about 0.1–0.4 mm month−1 in tissue culture medium, while the rates were in the range of 0.05–0.2 mm month−1 for PXS-based materials. Enzymatic Degradation was enhanced in relation to mechanical deformation, whereas PXS-based materials were influenced little. Hence, PXS, which is as soft as PGS but degrades significantly slower than PGS, is a better option for applications in tissue engineering of soft types.
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In Vitro Enzymatic Degradation of poly (glycerol sebacate)-based materials
Biomaterials, 2011Co-Authors: Shuling Liang, Xueyuan Yang, Xi-ya Fang, Wayne D. Cook, George Anthony Thouas, Qizhi ChenAbstract:Abstract Enzymatic Degradation is a major feature of polyester implants in vivo . An in vitro experimental protocol that can simulate and predict the in vivo Enzymatic Degradation kinetics of implants is of importance not only to our understanding of the scientific issue, but also to the well-being of animals. In this study, we explored the Enzymatic Degradation of PGS-based materials in vitro , in tissue culture medium or a buffer solution at the pH optima and under static or cyclic mechanical-loading conditions, in the presence of defined concentrations of an esterase. Surprisingly, it was found that the in vitro Enzymatic Degradation rates of the PGS-based materials were higher in the tissue culture medium than in the buffered solution at the optimum pH 8. The in vitro Enzymatic Degradation rate of PGS-based biomaterials crosslinked at 125 °C for 2 days was approximately 0.6–0.9 mm/month in tissue culture medium, which falls within the range of in vivo Degradation rates (0.2–1.5 mm/month) of PGS crosslinked at similar conditions. Enzymatic Degradation was also further enhanced in relation to mechanical deformation. Hence, in vitro Enzymatic Degradation of PGS materials conducted in tissue culture medium under appropriate Enzymatic conditions can quantitatively capture the features of in vivo Degradation of PGS-based materials and can be used to indicate effective strategies for tuning the Degradation rates of this material system prior to animal model testing.
