Synthesis of biomimetic segmented polyurethanes as antifouling biomaterials

Controlling the non-specific adsorption of proteins, cells and bacteria onto biomaterial surfaces is of crucial importance for the development of medical devices with specific levels of performance. Among the strategies pursued to control the interactions between material surfaces and biological tissues, the immobilization of non-fouling polymers on biomaterial surfaces as well as the synthesis of the so-called biomimetic polymers are considered promising approaches to elicit specific cellular responses. In this study, in order to obtain materials able to prevent infectious and thrombotic complications related to the use of blood-contacting medical devices, heparin-mimetic segmented polyurethanes were synthesized and fully characterized. Specifically, sulfate or sulfamate groups, known to be responsible for the biological activity of heparin, were introduced into the side chain of a carboxylated polyurethane. Due to the introduction of these groups, the obtained polymers possessed a higher hard/soft phase segregation (lower glass transition temperatures) and a greater hydrophilicity than the pristine polymer. In addition, the synthesized polymers were able to significantly delay the activated partial thromboplastin time, this increased hemocompatibility being related both to polymer hydrophilicity and to the presence of the -SO3H groups. This last feature was also responsible for the ability of these biomimetic polymers to prevent the adhesion of a strain of Staphylococcus epidermidis.