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Biodegradable Polyester

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Guillermo A Ameer – One of the best experts on this subject based on the ideXlab platform.

  • engineering Biodegradable Polyester elastomers with antioxidant properties to attenuate oxidative stress in tissues
    Biomaterials, 2014
    Co-Authors: Robert Van Lith, Jian Yang, Elaine K Gregory, Melina R Kibbe, Guillermo A Ameer

    Abstract:

    Oxidative stress plays an important role in the limited biological compatibility of many biomaterials due to inflammation, as well as in various pathologies including atherosclerosis and restenosis as a result of vascular interventions. Engineering antioxidant properties into a material is therefore a potential avenue to improve the biocompatibility of materials, as well as to locally attenuate oxidative stress-related pathologies. Moreover, Biodegradable polymers that have antioxidant properties built into their backbone structure have high relative antioxidant content and may provide prolonged, continuous attenuation of oxidative stress while the polymer or its degradation products are present. In this report, we describe the synthesis of poly(1,8-octanediol-co-citrate-co-ascorbate) (POCA), a citric-acid based Biodegradable elastomer with native, intrinsic antioxidant properties. The in vitro antioxidant activity of POCA as well as its effects on vascular cells in vitro and in vivo were studied. Antioxidant properties investigated included scavenging of free radicals, iron chelation and the inhibition of lipid peroxidation. POCA reduced reactive oxygen species generation in cells after an oxidative challenge and protected cells from oxidative stress-induced cell death. Importantly, POCA antioxidant properties remained present upon degradation. Vascular cells cultured on POCA showed high viability, and POCA selectively inhibited smooth muscle cell proliferation, while supporting endothelial cell proliferation. Finally, preliminary data on POCA-coated ePTFE grafts showed reduced intimal hyperplasia when compared to standard ePTFE grafts. This Biodegradable, intrinsically antioxidant polymer may be useful for tissue engineering application where oxidative stress is a concern.

  • A new Biodegradable Polyester elastomer for cartilage tissue engineering
    Journal of Biomedical Materials Research – Part A, 2006
    Co-Authors: Yong Kang, Jian Yang, Sadiya Khan, Lucas Anissian, Guillermo A Ameer

    Abstract:

    The objective of this study is to assess whether a new Biodegradable elastomer, poly(1,8-octanediol citrate) (POC), would be a suitable material to engineer elastomeric scaffolds for cartilage tissue engineering. Porous POC scaffolds were prepared via the salt-leaching method and initially assessed for their ability to rapidly recover from compressive deformation (% recovery ratio). Controls consisted of scaffolds made from other materials commonly used in cartilage tissue engineering, including 2% agarose, 4% alginate, non woven poly(glycolic acid) (PGA) meshes, and non woven poly(L-lactide-co-glycolide) (PLGA) meshes. Articular chondrocytes from bovine knee were isolated and seeded onto porous disk-shaped POC scaffolds, which were subsequently cultured in vitro for up to 28 days. POC scaffolds completely recover from compressive deformation, and the stress-strain curve is typical of an elastomer (recovery ratio>98%). Agarose gel (2%) scaffolds broke during the compression test. The recovery ratio of 4% alginate gel scaffolds, PLLA, and PGA were 72, 85, and 88%, respectively. The Young’s modulus of POC-chondrocyte constructs and cell-free POC scaffolds cultured for 28 days were 12.02+/-2.26 kPa and 3.27+/-0.72 kPa, respectively. After 28 days of culture, the recovery ratio of POC-chondrocyte constructs and cell-free POC scaffolds were 93% and 99%, respectively. The glycosaminoglycan (GAG) and collagen content at day 28 was 36% and 26% of that found in bovine knee cartilage explants. Histology/immunohistochemistry evaluations confirm that chondrocytes were able to attach to the pore walls within the scaffold, maintain cell phenotype, and form a cartilaginous tissue during the 28 days of culture.

  • Biodegradable Polyester elastomers in tissue engineering
    Expert Opinion on Biological Therapy, 2004
    Co-Authors: Antonio R. Webb, Jian Yang, Guillermo A Ameer

    Abstract:

    Tissue engineering often makes use of Biodegradable scaffolds to guide and promote controlled cellular growth and differentiation in order to generate new tissue. There has been significant research regarding the effects of scaffold surface chemistry and degradation rate on tissue formation and the importance of these parameters is widely recognised. Nevertheless, studies describing the role of mechanical stimuli during tissue development and function suggest that the mechanical properties of the scaffold will also be important. In particular, scaffold mechanics should be taken into account if mechanical stimulation, such as cyclic strain, will be incorporated into strategies to grow improved tissues or the target tissue to be replaced has elastomeric properties. Biodegradable Polyesters, such as polyglycolide, polylactide and poly(lactide-co-glycolide), although commonly used in tissue engineering, undergo plastic deformation and failure when exposed to long-term cyclic strain, limiting their use in engi…

Luc Averous – One of the best experts on this subject based on the ideXlab platform.

  • sepiolite as a promising nanoclay for nano biocomposites based on starch and Biodegradable Polyester
    Materials Science and Engineering: C, 2017
    Co-Authors: Eric Pollet, J B Olivato, J Marini, Fabio Yamashita, Maria Victoria Eiras Grossmann, Luc Averous

    Abstract:

    Abstract The effects of sepiolite addition (0, 1, 3 and 5 wt%) were evaluated on dynamic-mechanical behaviour, water uptake, thermal and optical properties of thermoplastic starch (TPS)/poly (butylene adipate- co -terephthalate) (PBAT) nano-biocomposites, with different TPS/PBAT (w/w) ratios and nanofiller contents. The results highlighted the improvement of the dynamic-mechanical behaviour with the addition of sepiolite, producing high performance materials. An increase of 25 °C in the T g of TPS was recorded by DMTA analysis at sepiolite content of 5 wt%. The sepiolite influenced the crystallisation of nano-biocomposites, without causing interference in the crystal organisation, evidenced by DSC analysis. The addition of sepiolite nanoclay decreased the water adsorption rate and water adsorption capacity of the corresponding nano-biocomposites. For such multiphase systems, the successful use of natural sepiolite brought a clear benefit, without the need of any modifications or additional processes to produce advanced nano-biocomposites.

  • nano biocomposites Biodegradable Polyester nanoclay systems
    Progress in Polymer Science, 2009
    Co-Authors: Perrine Bordes, Eric Pollet, Luc Averous

    Abstract:

    Abstract In the recent years, bio-based products have raised great interest since sustainable development policies tend to expand with the decreasing reserve of fossil fuel and the growing concern for the environment. Consequently, biopolymers, i.e., Biodegradable polymers, have been the topic of many researches. They can be mainly classified as agro-polymers (starch, protein, etc.) and Biodegradable Polyesters (polyhydroxyalkanoates, poly(lactic acid), etc.). These latter, also called bioPolyesters, can be synthesized from fossil resources but main productions are obtained from renewable resources. Unfortunately for certain applications, bioPolyesters cannot be fully competitive with conventional thermoplastics since some of their properties are too weak. Therefore, to extend their applications, these biopolymers have been formulated and associated with nano-sized fillers, which could bring a large range of improved properties (stiffness, permeability, crystallinity, thermal stability). The resulting ‘nano-biocomposites’ have been the subject of many recent publications. This review is dedicated to this novel class of materials based on clays, which are nowadays the main nanofillers used in nanocomposites systems. This review highlights the main researches and developments in bioPolyester/nanoclay systems during the last decade.

  • Nano-biocomposites: Biodegradable Polyester/nanoclay systems
    Progress in Polymer Science, 2009
    Co-Authors: Perrine Bordes, Eric Pollet, Luc Averous

    Abstract:

    Abstract In the recent years, bio-based products have raised great interest since sustainable development policies tend to expand with the decreasing reserve of fossil fuel and the growing concern for the environment. Consequently, biopolymers, i.e., Biodegradable polymers, have been the topic of many researches. They can be mainly classified as agro-polymers (starch, protein, etc.) and Biodegradable Polyesters (polyhydroxyalkanoates, poly(lactic acid), etc.). These latter, also called bioPolyesters, can be synthesized from fossil resources but main productions are obtained from renewable resources. Unfortunately for certain applications, bioPolyesters cannot be fully competitive with conventional thermoplastics since some of their properties are too weak. Therefore, to extend their applications, these biopolymers have been formulated and associated with nano-sized fillers, which could bring a large range of improved properties (stiffness, permeability, crystallinity, thermal stability). The resulting ‘nano-biocomposites’ have been the subject of many recent publications. This review is dedicated to this novel class of materials based on clays, which are nowadays the main nanofillers used in nanocomposites systems. This review highlights the main researches and developments in bioPolyester/nanoclay systems during the last decade.

J Fisher – One of the best experts on this subject based on the ideXlab platform.

  • contrasting biofunctionalization strategies for the enhanced endothelialization of Biodegradable vascular grafts
    Biomacromolecules, 2015
    Co-Authors: Anthony J Melchiorri, Narutoshi Hibino, Tai Yi, Tadahisa Sugiura, Shuhei Tara, Toshiharu Shinoka, Christopher K Breuer, J Fisher

    Abstract:

    Surface modification of Biodegradable vascular grafts is an important strategy to improve the in situ endothelialization of tissue engineered vascular grafts (TEVGs) and prevent major complications associated with current synthetic grafts. Important strategies for improving endothelialization include increasing endothelial cell mobilization and increased endothelial cell capture through biofunctionalization of TEVGs. The objective of this study was to assess two biofunctionalization strategies for improving endothelialization of Biodegradable Polyester vascular grafts. These techniques consisted of cross-linking heparin to graft surfaces to immobilize vascular endothelial growth factor (VEGF) or antibodies against CD34 (anti-CD34Ab). To this end, heparin, VEGF, and anti-CD34Ab attachment and quantification assays confirmed the efficacy of the modification strategy. Cell attachment and proliferation on these groups were compared to unmodified grafts in vitro and in vivo. To assess in vivo graft functionali…

  • photoinitiated cross linking of the Biodegradable Polyester poly propylene fumarate part ii in vitro degradation
    Biomacromolecules, 2003
    Co-Authors: J Fisher, Theresa A Holland, David Dean, Antonios G Mikos

    Abstract:

    This study investigated the in vitro degradation of both solid PPF networks and porous PPF scaffolds formed by photoinitiated cross-linking of PPF polymer chains. Three formulations of scaffolds of differing porosity and pore size were constructed by varying porogen size and content. The effects of pore size and pore volume on scaffold mass, geometry, porosity, mechanical properties, and water absorption were then examined. Throughout the study, the solid networks and porous scaffolds exhibited continual mass loss and slight change in length. Porogen content appeared to have the greatest effect upon physical degradation. For example, scaffolds initially fabricated with 80 wt % porogen content lost approximately 30% of their initial PPF content after 32 weeks of degradation, whereas scaffolds fabricated with 70 wt % porogen content lost approximately 18% after 32 weeks of degradation. For all scaffold formulations, water absorption capacity, porosity, and compressive modulus were maintained at constant val…