Novel Absorbable Polyurethane Biomaterials and Scaffolds for Tissue Engineering
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Novel Absorbable Polyurethane Biomaterials and Scaffolds for Tissue Engineering Syam P. Nukavarapu1,2,3,5, Rao S. Bezwada4, Deborah L. Dorcemus1,2, Neeti Srivasthava4, Robert J. Armentano1 1 Institute for Regenerative Engineering, University of Connecticut Health Center Farmington, CT 06030, U.S.A 2 Biomedical Engineering, University of Connecticut Storrs, CT 06269, U.S.A 3 Materials Science & Engineering, University of Connecticut Storrs, CT 06269, U.S.A 4 Bezwada Biochemical, LLC., Hillsborough, NJ, US. 5 Orthopedic Surgery, University of Connecticut Health Center, Farmington, CT 06030, U.S.A ABSTRACT This study reports a novel class of biodegradable polyurethane biomaterials and threedimensional scaffolds for tissue engineering. Solvent casted polyurethane films were studied for biocompatibility by seeding with human bone marrow derived stromal cells. In order to develop a three-dimensional and porous structure, a dynamic solvent sintering method was applied to the polyurethanes for the first time. Microstructural studies on the sintered scaffolds reveal porous structure formation with bonding between the adjacent microspheres. In conclusion, this study establishes new polyurethane biomaterials that are fully absorbable for tissue engineering applications. INTRODUCTION Polyurethanes (PUs) are an important class of biomaterials developed in the past primarily for biostable biomedical devices and their coatings [1-4]. Although polyurethanes find a wide range of industrial applications, segmented PU elastomers are of relevance to the medical industry due to their toughness, durability, biocompatibility, and biostability [2, 5]. In general, segmented polyurethanes are block co-polymers with an aliphatic polyol soft segment, and an aliphatic or aromatic hard segment; the soft segment is formed by the reaction between isocynate and polyol, while the hard segment is formed through a reaction between isocynate and chain extender. Segmented polyurethanes are prepared in two ways: (i) a single step process wherein isocynate, chain extender, and polyol are reacted together, or (ii) in a two step process wherein the isocynates and polyol are reacted to form pre-polymer, and then the pre-polymer is reacted with a chain extender [6, 7]. Recently, several segmented polyurethanes were synthesized to be biodegradable with the aim of developing biodegradable polyurethane scaffolds for tissue engineering and regenerative medicine applications. In this direction, several putative biodegradable polyurethanes are synthesized with polyester soft segments, and aliphatic or aromatic isocynate hard segments. These polyurethanes in various shapes and sizes have been investigated in vitro and in vivo for biocompatibility and biodegradability, and their ability to support cell in growth and tissue regeneration [8-12]. The main drawback of the existing class of polyurethanes is the lack of complete degradation. In the majority of cases, the soft segments of these polymers degrade but the hard segments, consisting of non-degradable isocyanates
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