DEVELOPMENT AND CHARACTERIZATION OF L-TYROSINE BASED POLYURETHANES FOR TISSUE ENGINEERING APPLICATIONS
Natural amino acid based synthetic polymers have limited applicability as biomaterial due to several unfavorable material and engineering properties. This has led to the development of a new class of polymers known as ‘pseudo poly(amino acid)s’. Several L-tyrosine based pseudo poly(amino acid)s have been developed and characterized extensively for biomaterial applications. Desaminotyrosine tyrosyl hexyl ester (DTH), a diphenolic dipeptide molecule developed from L-tyrosine and its metabolite, is used to synthesize amino acid based pseudo polymers with improved physical and chemical properties. Polyurethanes are extensively used as biomaterials due to excellent biocompatibility and the ability to tune the structure for a wide range of properties. The uses of polyurethanes are mainly focused on biostable implants and biomedical devices. But polyurethanes have shown their susceptibility to degradation under the conditions of their performance. The use of polyurethanes for tissue engineering applications emerged mainly due to the degradability of the polyurethanes. Biodegradable polyurethanes with degradable linkages are developed by altering their structure and composition. The aim of the research presented in this dissertation is focused on developing L-tyrosine based polyurethanes for biomaterial applications including tissue engineering. L-tyrosine based polyurethanes can be developed by using DTH as the chain extender with different polyols and diisocyantes. The use of amino acid based component will improve the biocompatibility and biodegradability of the polymers for tissue engineering application. In addition, by using the different components, the structure and composition of the polyurethanes can be altered to achieve a range of properties that are pertinent to biomaterial applications. This research describes the design, synthesis and characterization of L-tyrosine based polyurethanes with DTH as the chain extender. The polyurethanes are extensively characterized for different bioengineering properties, including surface characteristics, water absorption, degradation characteristics, and controlled release along with other important chemical, physical, thermal and mechanical characterizations. The structure-property relationships of the polyurethanes were investigated by developing a library of polyurethanes with different polyol and diisocyante. This library provides an important tool to design polyurethanes with relevant properties for biomaterial application. The effect of structure and composition of these polyurethanes in determining the material properties were studied in detail. In addition, blends of the polyurethanes were studied as an alternative to adjust different properties according to the requirements. The results show that L-tyrosine based polyurethanes are potential candidates for biomaterial applications including tissue engineering. The material characteristics are strongly dependent on the polyurethane structure and composition, and therefore a wide range of properties can be achieved by altering the structure and composition.
School:The University of Akron
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:l tyrosine polyurethane structure property tissue engineering biomaterial
Date of Publication:01/01/2007