Medical devices and methods of making the same
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 method of making a stent including a member, the method comprising: forming an outer layer of the stent on the member, the outer layer of the stent comprising an alloy comprising a radiopaque metal element and a second metal element, wherein the radiopaque metal element is selected from a group consisting of gold, palladium, and platinum; and oxidizing a portion of the alloy of the outer layer.
2. The method of claim 1 , wherein oxidizing the portion comprises forming an oxide from the outer layer.
3. The method of claim 1 , wherein oxidizing the portion comprises forming a nitride from the outer layer.
4. The method of claim 1 , further comprising forming a radiopaque layer comprising the radiopaque metal element.
5. The method of claim 1 , wherein the outer layer is formed with a compositional gradient.
6. The method of claim 1 , wherein the outer layer is formed by a process selected from the group consisting of physical vapor deposition, chemical vapor deposition, and electrodeposition.
7. The method of claim 1 , wherein oxidizing the portion of the outer layer is performed by electropolishing.
8. The method of claim 1 , wherein oxidizing the portion of the outer layer is performed by heating the outer layer in an oxidizing environment.
9. The method of claim 1 , wherein oxidizing the portion of the outer layer is performed by ion implanting oxygen in the outer layer and heating the outer layer.
10. The method of claim 1 , further comprising forming a polymeric layer on the outer layer.
11. The method of claim 1 , further comprising forming a drug-releasing layer on the outer layer.
12. The method of claim 1 , wherein the radiopaque metal is capable of attenuating an incident X-ray beam by more than about 70%.
13. The method of claim 1 , wherein the second metal element is selected from the group consisting of titanium, chromium, palladium, niobium, and silicon.
14. The method of claim 1 , wherein the member comprises a material selected from the group consisting of stainless steel and nickel-titanium alloy.
15. The method of claim 1 , wherein the outer layer defines an outer surface of the member.
16. The method of claim 1 , further comprising forming a second layer comprising the radiopaque metal element, the second layer disposed inwardly of the outer layer.
17. The method of claim 16 , wherein the outer layer has a lower oxidation potential than an oxidation potential of the second layer.
18. A method of making a stent including a member, the method comprising:
forming a first layer of a stent comprising a radiopaque metal element on the member, wherein the radiopaque metal element is selected from the group consisting of gold, platinum, and palladium;
forming a second layer of a stent comprising an alloy of the radiopaque metal element and a second metal element;
oxidizing a portion of the alloy of the second layer.