Possible Mechanism on Enhanced Blood Compatibility, Biostability, and Anticalcification of Sulfonated Polyethyleneoxide-Grafted Polyurethane

Abstract

To investigate the correlation between blood compatibility and biostability as well as the calcification-resistance of polymers, the surface of polyurethane (PU) was grafted with hydrophilic polyethyleneoxide (PEO), and further negatively charged sulfonate groups (S03) to produce PU-PEOIOOO and PU-PEOIOOOS03, respectively. PEO-S03 grafted PU surface showed great smoothness and high hydrophilicity. PU-PEOIOOO-S03 was much more blood compatible than untreated PU and PU-PEOlOOO from the results of in vitro platelet adhesion test and blood clotting times and ex vivo occlusion times. After 6 months implantation in rats, the degree of surface cracking and calcification on explanted PUs was decreased in the following order: PU ) PU-PEOIOOO ) PU-PEOlOOO-S03, meaning that PU-PEOlOOO-S03 is most promising as a biostable and calcification-resistant polymer. It is suggested that the more blood compatible modified PUs are, the more biostable and calcification-resistant. Such superior blood compatibility, biostability, and anticalcification of PU-PEOlOO 0-S03 might be attributed to the synergistic effect of nonadhesive and mobile PEO and negative sulfonate acid groups. Therefore, surface-modified PU-PEO-S03is expected to be useful for blood/tissue contacting biomedical material.