Dealloyed nanoporous stents

Abstract

The present invention relates generally to medical devices with therapy eluting components and methods for making same. More specifically, the invention relates to implantable medical devices having at least one porous layer, and methods for making such devices, and loading such devices with therapeutic agents. A mixture or alloy is placed on the surface of a medical device, then one component of the mixture or alloy is generally removed without generally removing the other components of the mixture or alloy. In some embodiments, a porous layer is adapted for bonding non-metallic coating, including drug eluting polymeric coatings. A porous layer may have a random pore structure or an oriented or directional grain porous structure. One embodiment of the invention relates to medical devices, including vascular stents, having at least one porous layer adapted to resist stenosis or cellular proliferation without requiring elution of therapeutic agents. The invention also includes methods, devices, and specifications for loading of drugs and other therapeutic agents into nanoporous coatings.

1 . A stent for insertion into a body structure, comprising: 
 a stent member comprising: 
 a first end and a second end,  
 a lumen extending along a longitudinal axis between the first end and the second end,  
 an ablumenal surface,  
 a lumenal surface;  
 a first porous layer, the first porous layer comprising a first surface, a first interstitial structure and a first interstitial space;  
   wherein the porous layer has a tortuosity factor of greater than about 1.1, an average thickness of less than 10 microns and a peak-valley surface roughness of less than about 2 microns.    
   
   
       2 . A polymer coated drug delivery stent, comprising: 
 a tubular metal body;    a porous layer on the body, wherein the pores of the porous layer have an angular component;    a bonding layer which is mechanically attached to the porous layer; and    a drug delivery layer bonded to the tie layer.    
   
   
       3 . A method of loading a porous medical device with a drug, comprising: 
 providing at least a component of a medical device having a porous zone, the porous zone comprising an interstitial structure, an interstitial space, an average depth and an average pore diameter;    removing gaseous material within the interstitial space by displacement with a vapor form of a first solvent; and    filling at least a portion of the interstitial space with at least one drug.    
   
   
       4 . The method of loading a porous medical device with a drug as in  claim 3 , further comprising removing a portion of the at least one drug by backsputter or oxygen plasma.  
   
   
       5 . The method of loading a porous medical device with a drug as in  claim 3 , further comprising altering the surface charge of the porous zone.  
   
   
       6 . The method of loading a porous medical device with a drug as in  claim 3 , further comprising altering the hydrophobicity of the porous zone.  
   
   
       7 . The method of loading a porous medical device with a drug as in  claim 3 , further comprising applying a binder to the porous zone before filling at least the portion of the interstitial space with the at least one drug.  
   
   
       8 . A stent for insertion into a body structure, comprising: 
 a stent member having: 
 a first end and a second end,  
 a lumen extending along a longitudinal axis between the first end and the second end,  
 an ablumenal surface,  
 a lumenal surface; and  
 at least one porous layer, the porous layer comprising an interstitial structure and an interstitial space;  
   wherein the interstitial space is generally configured by the removal of at least a portion of at least one sacrificial material by a thermal dealloying process from a mixture comprising at least one sacrificial material with one or more structural materials that comprise the interstitial structure of the porous layer; and    wherein the porous layer is adapted to receive and release at least one drug.    
   
   
       9 . A stent for insertion into a body structure, comprising: 
 a stent member having: 
 a first end and a second end,  
 a lumen extending along a longitudinal axis between the first end and the second end,  
 an ablumenal surface,  
 a lumenal surface;  
 at least one porous layer, the porous layer comprising a surface, an interstitial structure and an interstitial space; and  
 a polymeric coating bonded to at least a portion of the surface of the porous layer;  
   wherein the interstitial space is generally configured by the removal of at least one elemental sacrificial material from a mixture comprising at least one elemental sacrificial material with one or more elemental structural materials that comprise the interstitial structure of the porous layer.    
   
   
       10 . A method for forming a porous medical component, comprising: 
 providing a stent comprising a metallic surface;    chemically dealloying the metallic surface; and    thermally annealing the metallic surface.    
   
   
       11 . The method for forming a porous medical component as in  claim 10 , wherein the thermal annealing occurs after chemically dealloying the metallic surface.  
   
   
       12 . The method for forming a porous medical component as in  claim 10 , wherein the thermal annealing occurs before chemically dealloying the metallic surface.  
   
   
       13 . The method for forming a porous medical component as in  claim 10 , further comprising chemically annealing the metallic surface.  
   
   
       14 . A method for forming a porous medical component, comprising: 
 providing a stent comprising a metallic surface;    thermal dealloying the metallic surface; and    chemically annealing the metallic surface.    
   
   
       15 . The method for forming a porous medical component as in  claim 14 , wherein chemically annealing occurs after the thermal dealloying.  
   
   
       16 . A stent for insertion into a body structure, comprising: 
 a stent member comprising: 
 a first end and a second end,  
 a lumen extending along a longitudinal axis between the first end and the second end,  
 an ablumenal surface,  
 a lumenal surface; and  
 a porous layer, the porous layer comprising a lower section and an upper section;  
   wherein the lower section of the porous layer is loaded with an anti-restenosis drug and the upper layer is loaded with an anti-thrombosis drug.    
   
   
       17 . A stent for insertion into a body structure, comprising: 
 a stent member comprising: 
 a first end and a second end,  
 a lumen extending along a longitudinal axis between the first end and the second end,  
 an ablumenal surface,  
 a lumenal surface; and  
 a porous layer;  
 wherein the porous layer comprises a drug in a crystalline form.  
   
   
   
       18 . A stent for insertion into a body structure, comprising: 
 a stent member comprising: 
 a first end and a second end,  
 a lumen extending along a longitudinal axis between the first end and the second end,  
 an ablumenal surface,  
 a lumenal surface;  
 a abluminal porous layer; and  
 a lumenal porous layer;  
 wherein the abluminal porous layer is loaded with a first drug and the lumenal porous layer is loaded with a second drug different from the first drug.  
   
   
   
       19 . A medical device for insertion into a body, comprising a medical device having a porous surface exhibiting reduced neointimal formation compared to the same medical device lacking the porous surface.