Fabricating a stent formed from polymer-bioceramic composite with radiopaque bioceramic particles

Abstract

Fabricating a stent with a radiopaque layer including radiopaque bioceramic particles using coextrusion is disclosed.

What is claimed is: 
     
         1 . A method of fabricating a stent comprising:
 co-extruding a tube including a radiopaque layer and a non-radiopaque layer, the radiopaque layer comprising radiopaque bioceramic particles mixed within a first bioabsorable polymer, the non-radiopaque layer formed from a second bioabsorbable polymer; and   cutting a stent pattern in the tube to form a stent comprising a scaffolding, the scaffolding including a non-radiopaque layer and a radiopaque layer, the scaffolding non-radiopaque layer formed from the tube non-radiopaque layer and the scaffolding radiopaque layer formed from the tube radiopaque layer.   
     
     
         2 . The method of  claim 1 , wherein the radiopaque bioceramic particles comprise polymer chains grafted onto a surface of the bioceramic particles, wherein radiopaque functional groups are chemically bonded to the grafted polymer chains, the radiopaque functional groups allowing the stent to be fluoroscopically visible. 
     
     
         3 . The method of  claim 2 , wherein the polymer chains are grafted to hydroxyl groups on the surface of the bioceramic particles. 
     
     
         4 . The method of  claim 3 , wherein the bioceramic particles are selected from the group consisting of hydroxylapatite and calcium sulfate. 
     
     
         5 . The method of  claim 1 , wherein the radiopaque bioceramic particles comprise radiopaque functional groups grafted to a surface of the bioceramic particles, the radiopaque functional groups allowing the stent to be fluoroscopically visible. 
     
     
         6 . The method of  claim 5 , wherein the radiopaque functional groups are chemically bonded to reactive groups including hydroxyl groups on the ceramic surface of the bioceramic particles. 
     
     
         7 . The method of  claim 6 , wherein the radiopaque functional groups are grafted to the surface of the bioceramic particles by an esterification reaction of hydroxyl groups of the bioceramic particles with the radiopaque functional groups. 
     
     
         8 . The method of  claim 1 , wherein the co-extrusion of the tube comprises co-extrusion of the first bioabsorbable polymer with the second bioabsorbable polymer, the first bioabsorbable polymer including the radiopaque material mixed therein. 
     
     
         9 . The method of  claim 1 , wherein the stent pattern is cut by laser machining.