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Degradation of Poly(Anhydride-Co-Imides): Novel Polymers for Orthopedic Applications

Published online by Cambridge University Press:  21 February 2011

Kathryn E. Uhrich
Affiliation:
Massachusetts Institute of Technology, Department of Chemical Engineering, Cambridge, MA 02139
Sobrasua E. M. Ibim
Affiliation:
Massachusetts Institute of Technology, Department of Chemical Engineering, Cambridge, MA 02139
Cato T. Laurencin
Affiliation:
Medical College of Pennsylvania, Department of Orthopedics, Philadelphia, PA 19129
Robert Langer
Affiliation:
Massachusetts Institute of Technology, Department of Chemical Engineering, Cambridge, MA 02139
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Abstract

Novel polymers with good mechanical properties are being developed as degradable matrices for bone growth and regeneration. The poly(anhydride-co-imides) were synthesized from trimellitylimidoglycine and 1,6-bis(p-carboxyphenoxy)hexane in molar compositions of 10:90, 30:70 and 50:50. These polymers have compressive strengths (23–57 MPa), which are similar to human cortical bone. 1 In vitro degradation was performed under acidic (pH 5), physiological (pH 7.4), and basic (pH 10) conditions. The degradation rate increased under basic conditions and by increasing the amount of trimellitylimidoglycine in the polymer backbone. Two erosion zones were observed in the polymers by microscopy. In vivo polymer degradation was evaluated by characterizing polymer discs implanted in subcutaneous tissue of rats over a 56 day time period. Copolymers with the highest ratio of trimellitylimidoglycine in the polymer backbone were completely degraded by 56 days, the other compositions remained in the tissue as solid pellets at this time. In vivo degradation was much slower than the corresponding in vitro degradation.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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