Biocompatibility and hemocompatibility evaluation of polyether urethanes synthesized using DBU organocatalyst

Biomaterials must fulfill some requirements before moving into in vivo application. In vitro test is usually conducted as a preliminary screening evaluation. Although most of the studies are focused in the cytotoxicity, interactions between blood elements and the biomaterials or hemocompatibility must also be considered. Aliphatic polyurethanes have been always considered ideal candidates for in-vivo application due to their versatility. However, the utilization of metal catalyst to promote the polymerization have limited their use. Recently, some organocatalysts have shown to be competitive to tin based catalyst for the preparation of polyurethanes and have relaunched their use in biomedicine. In the present study we carried out the organocatalyzed polymerization of 5 commercially available isocyanates, hexamethylene diisocyanate, isophorone diisocyanate, trans-1,4-cyclohexylene diisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate) and L-lysine diisocyanate to analyze the cytotoxicity and hemocompatibility of the resultant polymers as a function of the employed diisocyanate. The diisocyanates were polymerized with hydroxy end-capped oligomeric poly (tetramethylene glycol) (PT2K) as the long chain diol and 1,3-propanediol as the short chain diol. We demonstrated that from selected diisocyanates, lysine diisocyanate based polyurethanes possessed lower cytotoxicity and better hemocompatibility than the other polyurethanes. In comparison with a well known blood compatible polymer such as poly(2-methoxyethyl acrylate), the lysine diisocyanate based polyurethanes showed remarkable values in terms of cytotoxicity and platelet adhesion, but major levels of protein adsorption.