Improved hemocompatibility of poly(ethylene terephthalate) modified with various thiol-containing groups.

Thiol groups were attached to polyethylene terephthalate (PET) to promote the transfer of a known platelet inhibitor, nitric oxide (NO), from nitrosated thiols naturally found in the body to PET, followed by the release of NO from PET to prevent platelet adhesion. In order to immobilize the most thiols on the modified polymer, the processing parameters used to attach the following three thiol containing groups were assessed: L-cysteine, 2-iminothiolane, and a cysteine polypeptide. When comparing the immobilized concentrations of thiol groups from each of the optimized processes the amount of immobilized thiol groups increased in order with the following groups: cysteine polypeptide <2-iminothiolane <L-cysteine. The effect of each optimized polymer on platelet adhesion was studied by in vitro experiments utilizing a parallel plate perfusion chamber. Platelets in the following solutions were tested: Tyrode's buffer, 7 microm nitrosated bovine serum albumin in Tyrode's buffer, 50% plasma in Tyrode's buffer, and 50% whole blood in Tyrode's buffer. All of the polymers demonstrated a significant decrease in platelet adhesion compared to controls when exposed to the BSANO, plasma and whole blood solutions. The most significant decrease was for the L-cysteine modified polymer in the plasma solution with a 65% decrease.