Oxidative and enzymatic degradations of L-tyrosine based polyurethanes

Oxidative and enzymatic degradations Of L-tyrosine based polyurethanes were studied for biomaterial applications. Oxidative degradation was performed with 0.1 M cobalt chloride (CoCl2) in hydrogen peroxide solutions at 37 degrees C and the degradation was assessed by ATR-FTIR. Results indicate that polyurethane with polyethylene glycol (PEG) shows soft segment degradation while polyurethane based on polycaprolactone (PCL) shows hard segment degradation. Enzymatic degradation of the polyurethanes was studied using proteolytic enzyme a-chymotrypsin in phosphate buffer solution (pH 7.4) at 37 degrees C. The enhanced degradability Of L-tyrosine based polyurethanes is due to both the presence of amino acid based chain extender and the action of enzyme. The changes in the morphology of polyurethanes were analyzed by SEM. The results of the degradation study were correlated to the structure of the polyurethanes. (c) 2007 Elsevier Ltd. All rights reserved.