SURFACE MODIFICATION OF ePTFE AND IMPLANTS USING THE SAME

Abstract

A method for modifying an ePTFE surface by plasma immersion ion implantation includes the steps of providing an ePTFE material in a chamber suitable for plasma treatment; providing a continuous low energy plasma discharge onto the sample; and applying negative high voltage pulses of short duration to form a high energy ion flux from the plasma discharge to generate ions which form free radials on the surface of the ePTFE material without changing the molecular and/or physical structure below the surface to define a modified ePTFE surface. The step of applying the high voltage pulses modifies the surface of the ePTFE without destroying the node and fibril structure of the ePTFE, even when the step of applying the high voltage pulses etches and/or carburizes the surface of the ePTFE. The modified surface may have a depth of about 30 nm to about 500 nm. The ions are dosed onto the ePTFE sample at concentrations or doses from about 10 13 ions/cm 2 to about 10 16 ions/cm 2 .

1 . An implantable medical device comprising:
 ePTFE having a surface modified by plasma immersion ion implantation; and   polysaccharide hydroxyethyl starch groups covalently bonded to the modified surface.   
     
     
         2 . The implantable medical device of  claim 1 , further comprising a bioactive agent bonded to the polysaccharide hydroxyethyl starch groups. 
     
     
         3 . The implantable medical device of  claim 2 , further comprising a biodegradable spacer molecule bonded to the modified surface or to the polysaccharide hydroxyethyl starch groups. 
     
     
         4 . The implantable medical device of  claim 2 , wherein the bioactive agent is selected from the group consisting of anti-thrombogenic agents, anti-proliferative agents, anti-inflammatory agents, antineoplastic/antiproliferative/anti-mitotic agents, anti-coagulants, vascular cell growth promoters, vascular cell growth inhibitors, cholesterol-lowering agents; vasodilating agents; agents which interfere with endogenous vasoactive mechanisms, cell adhesion factors; and combinations thereof. 
     
     
         5 . The implantable medical device of  claim 1 , wherein the device is a graft or a stent-graft. 
     
     
         6 . An implantable medical device comprising:
 ePTFE having a surface modified by plasma immersion ion implantation; and   hydrophilic acrylamide groups covalently bonded to the modified surface.   
     
     
         7 . The implantable medical device of  claim 6 , further comprising a bioactive agent bonded to the hydrophilic acrylamide groups. 
     
     
         8 . The implantable medical device of  claim 6 , further comprising a biodegradable spacer molecule bonded to the modified surface or to the hydrophilic acrylamide groups. 
     
     
         9 . The implantable medical device of  claim 7 , wherein the bioactive agent comprises anti-thrombogenic agents, anti-proliferative agents, anti-inflammatory agents, antineoplastic/antiproliferative/anti-mitotic agents, anti-coagulants, vascular cell growth promoters, vascular cell growth inhibitors, cholesterol-lowering agents; vasodilating agents; agents which interfere with endogenous vasoactive mechanisms; cell adhesion factors; and combinations thereof. 
     
     
         10 . The implantable medical device of  claim 6 , wherein the device is a graft or a stent-graft. 
     
     
         11 . An implanted, surface modified ePTFE graft, comprising:
 ePTFE having a node and fibril structure and having a carburized surface formed by plasma immersion ion implantation without destroying the node and fibril structure and having cellular material attached to the fibrils or attached to functional groups covalently bonded to the fibrils and substantially covering and/or filling the nodes.