Medical devices and methods of making the same

Abstract

An endoprosthesis, such as a stent, having a layer that can enhance the biocompatibility of the endoprosthesis, and methods of making the endoprosthesis are disclosed.

1 . A medical implant, comprising:
 a member including at least a first portion, the first portion comprising an oxide-rich surface layer and an alloy of a radiopaque material and a second material, the oxide-rich surface layer defining an outer surface of the member, the oxide-rich surface layer comprising an oxidized form of the alloy.   
     
     
         2 . The medical implant of  claim 1 , wherein the member comprises a second portion disposed inwardly of the first portion. 
     
     
         3 . The medical implant of  claim 2 , wherein the first portion includes a first layer consisting essentially of the radiopaque material, a second layer comprising the alloy disposed outwardly of the first layer, and the oxide-rich surface layer disposed outwardly of the second layer. 
     
     
         4 . The medical implant of  claim 3 , wherein the first layer is more radiopaque than the second portion. 
     
     
         5 . The medical implant of  claim 2 , wherein the second portion comprises a material selected from the group consisting of stainless steel and nickel-titanium alloy. 
     
     
         6 . The medical implant of  claim 2 , further comprising a third portion between the first portion and the second portion. 
     
     
         7 . The medical implant of  claim 1 , wherein the radiopaque material is selected from the group consisting of gold, platinum, palladium, and tantalum. 
     
     
         8 . The medical implant of  claim 1 , wherein the second material is selected from the group consisting of titanium, chromium, palladium, niobium, and silicon. 
     
     
         9 . The medical implant of  claim 1 , further comprising a polymeric layer on the member. 
     
     
         10 . The medical implant of  claim 1 , further comprising a drug-releasing layer on the member. 
     
     
         11 . The medical implant of  claim 1 , wherein the alloy comprises a = concentration gradient of the radiopaque material. 
     
     
         12 . The medical implant of  claim 11 , wherein the concentration of the radiopaque material increases as a function of distance from the outer surface. 
     
     
         13 . The medical implant of  claim 11 , wherein the concentration gradient varies substantially linearly along a thickness of the first portion. 
     
     
         14 . The medical implant of  claim 1 , wherein the radiopaque material is capable of attenuating an incident X-ray beam by more than about 70%. 
     
     
         15 . The medical implant of  claim 1 , wherein the radiopaque material is gold and the second material is titanium. 
     
     
         16 . The medical implant of  claim 1 , wherein the alloy has a greater oxidation potential than the radiopaque material alone. 
     
     
         17 . The medical implant of  claim 1 , wherein the medical implant is an orthopedic implant. 
     
     
         18 . The medical implant of  claim 1 , wherein the medical implant is a stent or stent-graft. 
     
     
         19 . The medical implant of  claim 1 , wherein the member is a tubular member defined by struts and openings.