Characterization of polyurethane scaffold surface functionalization with diamines and heparin

Abstract

Polyurethane scaffolds (PUs) have a good biocompatibility but lack cell recognition sites. In this study, we functionalized the surface of a PU, P(D/L)LA and PCL (50:50) containing urethane segments, with heparin. The first step in this functionalization, aminolysis, lead to free amine groups on the surface of the PU. Free amine content was determined to be 6.4 nmol/mL/mg scaffold, a significant increase of 230%. Subsequently, heparin was crosslinked. Immunohistochemistry demonstrated the presence of heparin homogeneous throughout the 3D porous scaffold. Young's modulus decreased significantly till 50% of the native stiffness after aminolysis and did not change after heparin crosslinking. Contact angle on PU films significantly decreased from 82.7° to 64.3° after heparin crosslinking, indicating a more hydrophilic surface. This functionalization beholds great potential for tissue engineering purposes. When used in a load-bearing environment, caution is necessary due to reduction in mechanical stiffness.