In vivo biostability of polyether polyurethanes with fluoropolymer and polyethylene oxide surface modifying endgroups; resistance to metal ion oxidation

Polyether polyurethanes are subject to oxidation catalyzed by, and through direct (redox) reaction with transition metal ions (metal ion oxidation, MIO). The source of the ions is corrosion of metallic parts within an implanted device. A Shore 80A polyether polyurethane was modified with fluoropolym...

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Bibliographic Details
Published in:Journal of biomedical materials research. Part A 2007-01, Vol.80A (1), p.34-44
Main Authors: Ward, Robert, Anderson, James, McVenes, Rick, Stokes, Ken
Format: Article
Language:English
Subjects:
Animals
biostability
Coated Materials, Biocompatible
Cobalt
Corrosion
fluorocarbon modified polyurethane
Fluorocarbon Polymers
Ions
Materials Testing
MIO
Oxidation-Reduction
Polyethylene Glycols
polyethylene oxide modified polyurethane
Polyurethanes
Prostheses and Implants
Rabbits
surface modifying end group
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Summary:Polyether polyurethanes are subject to oxidation catalyzed by, and through direct (redox) reaction with transition metal ions (metal ion oxidation, MIO). The source of the ions is corrosion of metallic parts within an implanted device. A Shore 80A polyether polyurethane was modified with fluoropolymer (E80AF) or polyethylene oxide (E80AP) surface modifying end groups (SME). The SME migrates to the surface to form a covalently bonded monolayer, while maintaining the bulk properties of the polyurethane. In vitro tests in H2O2 solution indicated that both SME's accelerated MIO. Tubing samples containing cobalt mandrels were implanted in the subcutis of rabbits for up to 2 years. In vivo, E80AF significantly slowed the rate of visible degradation, but did not prevent MIO. E80AP had virtually identical visual performance to the unmodified control in vivo. Infrared spectroscopy and molecular weight correlated well with visual appearance. When cracks were seen, polyether soft segment oxidation was occurring. Both E80AP and the control developed severe loss of molecular weight in vivo. The changes were much less severe for E80AF. Thus, contrary to in vitro test results, the PEO SME had no effect at all on MIO resistance, while the fluoropolymer SME produced a significant improvement in biostability. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
ISSN:1549-3296
1552-4965
DOI:10.1002/jbm.a.30860