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Calcification Resistant Polyurethanes Modified with Geminal Bisphosphonate Groups

Published online by Cambridge University Press:  10 February 2011

I. S. Alferiev
Affiliation:
Children's Hospital of Philadelphia, 3516 Civic Center Blvd., Philadelphia, PA 19104
N. R. Vyavahare
Affiliation:
Children's Hospital of Philadelphia, 3516 Civic Center Blvd., Philadelphia, PA 19104
C. X. Song
Affiliation:
Children's Hospital of Philadelphia, 3516 Civic Center Blvd., Philadelphia, PA 19104
R. J. Levy
Affiliation:
Children's Hospital of Philadelphia, 3516 Civic Center Blvd., Philadelphia, PA 19104
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Abstract

Non-esterified geminal bisphosphonate groups (0.06–0.12 mmol/g) were covalently attached to elastomeric polyurethanes (PU) based on 4,4′-methylenebis(phenyl isocyanate) (MDI) and represented by a polyether-urethane (PEU), a polyurethane-urea (PUU), and a polycarbonate-urethane (PCU). Auxiliary 6-bromohexyl or carboxylic groups were attached to PU via base-induced N-alkylation of urethane NH sites either with 1,6-dibromohexane or with lithium salts of ω-bromocarboxylic acids. An alternative method to introduce carboxylic groups into the polymers via reactions of bromoalkylated PU with thiol-containing carboxylic acids was found to be more suitable than the direct carboxyalkylation. The subsequent reactions either of thiol-containing bisphosphonates with the attached 6-bromohexyl groups or of 3-amino-Ihydroxypropylidene-1,1-bisphosphonate (pamidronate) with N-hydroxysuccinimide-activated carboxylic groups of PU led to the bisphosphonate-modified PU. The polymers do not undergo a significant degradation in the course of the modification reactions, their mechanical properties and elasticity remain mostly unaffected. Water uptake of the bisphosphonate-modified PU increased up to 26% depending on the extent of modification. Bisphosphonate-modified PUU showed a significantly lower in vivo calcification compared to the non-modified polymer.

Type
Research Article
Copyright
Copyright © Materials Research Society 2000

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