Covalently grafted phospholipid monolayer on silicone catheter surface for reduction in platelet adhesion

We report a novel method of surface grafting a polymeric phospholipid system containing an acryloyl end group (1stearoyl-2-[12-(acryloyloxy)-dodecanoyl]-sn-glycero-3-phosphocholine) onto medical grade silicone catheters. The surface of silicone catheters was functionalized in a sequence of steps: plasma polymerization of allyl alcohol on the catheter surface, grafting acryloyl moieties and in situ polymerization of the pre-assembled acryloyl terminated phospholipids on the acryloyl functionalized catheter surface. The surface morphological changes analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), a sharp decrease in water contact angle, and appearance of N1s peak in XPS analysis indicated a successful monolayer grafting of the phospholipid. In platelet adhesion tests performed using platelets isolated from rabbit plasma, the phospholipid grafted surface showed fewer adhered platelets, without emerging pseudopodes or aggregation. However, ungrafted catheter surface showed large number of platelets in extensively spread and aggregated states. Thus, this modified phospholipid system and its simple grafting technique was very effective with regard to suppressing in vitro platelet adhesion on the silicon catheter surface.