Processing and in vitro Degradation of Starch/EVOH Thermoplastic Blends

Reis, Rui L.; Mendes, Sofia Silva; Cunha, António M.; Bevis, M.

doi:10.1002/(sici)1097-0126(199708)43:4<347::aid-pi764>3.3.co;2-3

Cited by 50 publications

(71 citation statements)

References 2 publications

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“…These unloaded SPCL microparticles had an average size distribution of 102.3 ± 4.1 lm [3]. The samples were sterilized by ethylene oxide using preoptimized conditions as described by Reis et al [41].…”

Section: Methodsmentioning

confidence: 99%

Starch-poly-є-caprolactone Microparticles Reduce the Needed Amount of BMP-2

Balmayor

Feichtinger

Azevedo

et al. 2009

Clin Orthop Relat Res

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BMP-2 is currently administered clinically using collagen matrices often requiring large amounts of BMP-2 due to burst release over a short period of time. We developed and tested a novel injectable drug delivery system consisting of starch-poly-e-caprolactone microparticles for inducing osteogenesis and requiring smaller amounts of BMP-2. We evaluated BMP-2 encapsulation efficiency and the in vitro release profile by enzyme-linked immunosorbent assay. BMP-2 was rapidly released during the first 12 hours, followed by sustained release for up to 10 days. We then evaluated the osteogenic potential of dexamethasone (standard osteogenic induction agent) and BMP-2 after incorporation and during release using an osteo/myoblast cell line (C2C12). Alkaline phosphatase activity was increased by released BMP-2. Mineralization occurred after stimulation with BMP-2-loaded microparticles. A luciferase assay for osteocalcin promoter activity showed high levels of activity upon treatment with BMP-2-loaded microparticles. In contrast, no osteogenesis occurred in C2C12 cells using dexamethasone-loaded microparticles. However, human adipose stem cells exposed to the microparticles produced high amounts of alkaline phosphatase. The data suggest starch-poly-e-caprolactone microparticles are suitable carriers for the incorporation and controlled release of glucocorticoids and growth factors. Specifically, they reduce the amount of BMP-2 needed and allow more sustained osteogenic effects.

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Section: Methodsmentioning

confidence: 99%

Starch-poly-є-caprolactone Microparticles Reduce the Needed Amount of BMP-2

Balmayor

Feichtinger

Azevedo

et al. 2009

Clin Orthop Relat Res

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“…The amount of starch was 50 per cent by weight (wt%) on SCA and SEVA-C and 30 wt% on SPCL. Ten millimetre disc samples were prepared by injection moulding and then sterilized by ethylene oxide in optimized conditions (Reis et al 1997). …”

Section: Starch-based Biomaterialsmentioning

confidence: 99%

The competitive adsorption of human proteins onto natural-based biomaterials

Alves

Reis

Hunt

2010

J. R. Soc. Interface.

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This study aims to further the understanding of nanoscale structures relevant for cellular recognition on contact and interaction with natural-based materials. The correlation between surface characteristics and protein adsorption from unitary and complex protein systems was investigated with respect to altering the bulk chemistry of the substrate material. Polymeric blends of starch and cellulose acetate, polycaprolactone (SPCL) and ethylene vinyl alcohol (SEVA-C) were used. Different proteins, bovine serum albumin, human serum albumin (HSA) and human fibronectin (HFN), were selected for this study. The construction of adsorption isotherms is an important starting point towards characterizing the interactions between surfaces and proteins. In this study, albumin adsorption isotherms fit the Freundlich model and were correlated with the chemistry and morphology of surfaces. In addition, protein distribution, quantification and competition were measured using fluorimetry and visualized by confocal microscopy. The analysis of unitary systems demonstrated that the adsorption of HSA was generally lower than that of HFN. In the latter case, SPCL and SEVA-C blends reached adsorption values of 97 and 89 per cent, respectively. In studying the co-adsorption of proteins, an increase in both HSA and HFN on SEVA-C surfaces was observed. SPCL showed no substantial increase in the adsorption of the proteins in competitive conditions. The similarity of these materials with other polysaccharide-based materials increases the relevance of the presented results. This study provides valuable information for the development of strategies towards the control of protein orientation and functionality as the availability of cell signalling epitopes for a broader family of materials that continue to be a significant component of this field of research.

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“…Prior to culturing, all the membranes were sterilized with ethylene oxide under previously described conditions. [32] …”

Section: Direct Contact Assay -Cell Adhesion and Proliferation On Chimentioning

confidence: 99%

Plasma Surface Modification of Chitosan Membranes: Characterization and Preliminary Cell Response Studies

Silva

Luna

Gomes

et al. 2008

Macromolecular Bioscience

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132

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Surface modification of biomaterials is a way to tailor cell responses whilst retaining the bulk properties. In this work, chitosan membranes were prepared by solvent casting and treated with nitrogen or argon plasma at 20 W for 10-40 min. AFM indicated an increase in the surface roughness as a result of the ongoing etching process. XPS and contact angle measurements showed different surface elemental compositions and higher surface free energy. The MTS test and direct contact assays with an L929 fibroblast cell line indicated that the plasma treatment improved the cell adhesion and proliferation. Overall, the results demonstrated that such plasma treatments could significantly improve the biocompatibility of chitosan membranes and thus improve their potential in wound dressings and tissue engineering applications.

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Processing and in vitro Degradation of Starch/EVOH Thermoplastic Blends

Cited by 50 publications

References 2 publications

Starch-poly-є-caprolactone Microparticles Reduce the Needed Amount of BMP-2

Starch-poly-є-caprolactone Microparticles Reduce the Needed Amount of BMP-2

The competitive adsorption of human proteins onto natural-based biomaterials

Plasma Surface Modification of Chitosan Membranes: Characterization and Preliminary Cell Response Studies

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