Bioerodible endoprosthesis with biostable inorganic layers

Abstract

Medical devices such as endoprostheses (e.g., stents) containing one or more biostable layers (e.g., biostable inorganic layers) and a biodegradable underlying structure are disclosed.

1 - 21 . (canceled) 
     
     
         22 . A method of making a stent comprising a biostable layer and an underlying structure, comprising:
 modifying a selected portion of the surface of the underlying structure with hydroxyl groups;   allowing the hydroxyl groups to react with one or more metal alkoxides to form a covalently-bound surface monolayer of the one or more metal alkoxides;   (optionally) removing excess adsorbed metal alkoxide; and   hydrolyzing the covalently-bound surface monolayer.   
     
     
         23 . The method of  claim 22 , further comprising applying a bioerodible polymer layer onto at least a portion of the biostable layer. 
     
     
         24 . A method of making a stent comprising a biostable layer and a bioerodible structure, comprising:
 forming the biostable layer on a surface of a substantially tubular polymer;   exposing the biostable layer to temperature sufficiently elevated to remove the tubular polymer whereas the biostable layer remains substantially intact; and   applying a bioerodible polymer to the biostable layer.   
     
     
         25 . The method of  claim 24 , further comprising applying a bioerodible polymer layer onto at least a portion of the biostable layer. 
     
     
         26 . A stent comprising a sent wall including fenestrations separated by struts, the struts comprising a bioerodible metal and an overlying ceramic layer having a thickness of less than 20 nm. 
     
     
         27 . The stent of  claim 26 , wherein the overlying ceramic layer is about 5% or less of the wall thickness. 
     
     
         28 . The stent of  claim 26 , wherein the overlying ceramic layer has a thickness on average of about 10 to 20 nm. 
     
     
         29 . The stent of  claim 26 , wherein the overlying ceramic layer has a thickness about 1 nm. 
     
     
         30 . The stent of  claim 26 , wherein the overlying ceramic layer comprises one or more metal oxides. 
     
     
         31 . The stent of  claim 26 , wherein the overlying ceramic layer comprises one or more of titanium oxide, ruthenium oxide, or iridium oxide. 
     
     
         32 . The stent of  claim 26 , wherein the overlying ceramic layer comprises a crystalline form of titanium oxide. 
     
     
         33 . The stent of  claim 26 , wherein the overlying ceramic layer comprises a plurality of nodules about 15-20 nm in size. 
     
     
         34 . The stent of  claim 26 , wherein the bioerodible metal is a bioerodible metal alloy. 
     
     
         35 . The stent of  claim 26 , wherein the ceramic layer is on a surface of the struts. 
     
     
         36 . The stent of  claim 26 , wherein the ceramic layer is on an interior surface, an exterior surface or a sidewall of the stent. 
     
     
         37 . The stent of  claim 26 , wherein at least a portion of the ceramic layer is covered by a bioerodible layer. 
     
     
         38 . The stent of  claim 26 , wherein the ceramic layer formed by a sol-gel process. 
     
     
         39 . The stent of  claim 26 , wherein the ceramic layer is formed by a process comprising:
 modifying a selected portion of a bioerodible metal of a stent wall;   allowing the hydroxyl groups to react with one or more metal alkoxides to form a covalently-bound ceramic layer of the one or more metal alkoxides;   (optionally) removing excess adsorbed metal alkoxide; and   hydrolyzing the covalently-bound surface of the ceramic layer.   
     
     
         40 . The stent of  claim 26 , wherein the ceramic layer is a monolayer. 
     
     
         41 . The stent of  claim 26 , comprising one or more monolayers of a metal oxide, an organic material, a polymeric material or a biological material.