Microstructured absorbable implant

Patent metadata

Field	Value
Publication number	US-9504554-B2
Application number	US-201414146550-A
Country	US
Kind code	B2
Filing date	Jan 2, 2014
Priority date	Jan 16, 2013
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

The production of microstructured surfaces in magnesium alloys, containing zinc as the major alloying element, in particular in absorbable implants such as stents, wherein microstructures in sizes of up to 5 μm (micrometers) are generated on a magnesium alloy base body of the absorbable implant, for example of the absorbable stent, by way of optionally combined, pickling and electrochemical micropolishing processes, and allow better adhesion of a polymer coating (including higher break resistance) and higher corrosion resistance. The microstructured surface is produced out of the bulk material and exhibits no delamination from the base material during the mechanical deformation of the implant.

First claim

What is claimed is:

1. A method for producing a microstructured surface, the method comprising:
forming a semi-finished product comprising a bioresorbable magnesium alloy with zinc and/or aluminum as a major alloying element, wherein a surface of the semi-finished product has a grain structure having a mean grain size of less than or equal to 10 μm;
pickling the semi-finished product to dissolve individual grains to produce the microstructured surface of raised grain boundaries with neighboring depressions up to 3 μm deep and up to 10 μm wide; and
electropolishing the pickled product to smooth surface edges.

2. The method for producing a microstructured surface according to claim 1 , characterized in that the magnesium alloy has a heterogeneous and/or no preferred crystallographic orientation.

3. The method for producing a microstructured surface according to claim 1 , characterized in that the crystallography of the magnesium alloy does not tend, or tends only insignificantly, toward the formation of secondary phases and/or does not tend, or tends only insignificantly, toward precipitations.

4. The method for producing a microstructured surface according to claim 1 , characterized in that the surface comprises grains having differing zinc contents and/or aluminum contents prior to the pickling process.

5. The method for producing a microstructured surface according to claim 1 , characterized in that the grain structure has a mean grain size of 1 to 5 μm.

6. The method for producing a microstructured surface according to claim 1 , characterized in that the microstructured surface has a microstructure that is made of a grain structure having a mean grain size of 1 to 8 μm.

7. The method for producing a microstructured surface according to claim 1 , characterized in that the pickling process and the electropolishing process are carried out using a same phosphoric acid-containing electrolyte.

8. The method for producing a microstructured surface according to claim 7 , characterized in that the phosphoric acid containing electrolyte is a composition selected from the group consisting of 15 to 25% by volume or approximately 20% by volume being deionized water; 25 to 35% by volume or approximately 30% by volume being phosphoric acid (85%); and 45 to 55% by volume or approximately 50% by volume being ethanol (50%), based on 100% by volume of the electrolyte composition.

9. The method for producing a microstructured surface according to claim 1 , characterized in that the major alloying element is provided in a total quantity selected from the group consisting of 1 to 20% by weight, 3 to 10% by weight, 4 to 7% by weight, and 4.5 to 5.5% by weight.

10. The method for producing a microstructured surface according to claim 1 , characterized in that the semi-finished product has zinc and aluminum as a major alloying elements.

11. The method for producing a microstructured surface according to claim 1 , characterized in that the semi-finished product is shaped as stent-shaped structure.

12. The method for producing a microstructured surface according to claim 1 , characterized in that the magnesium alloy comprises zinc and calcium.

13. The method for producing a microstructured surface according to claim 1 , characterized in that the magnesium alloy comprises zinc, and calcium in the following proportions: 94.75% by weight Mg, 5.0% by weight Zn and 0.25% by weight Ca.

14. The method for producing a microstructured surface according to claim 1 , characterized in that the magnesium alloy comprises zinc in the following proportions: 95.0% by weight Mg and 5.0% by weight Zn.

15. The method for producing a microstructured surface according to claim 1 , the method further comprising pickling the smoothed product after the electropolishing step to dissolve individual grains.

16. The method for producing a microstructured surface according to claim 7 , the method further comprising pickling the smoothed product in the same phospohoric acid-containing electrolyte after the electropolishing step to dissolve individual grains.

Assignees

• Biotronik Ag

Inventors

• Bayer Ullrich
• Badendieck Monika
• Peters Susanne
• Drobek Thomas
• Anopuo Okechukwu

Classifications

• C22C23/02 Primary

  with aluminium as the next major constituent · CPC title

• A61L31/022

  Metals or alloys · CPC title

• C25F3/04

  of light metals · CPC title

• A61F2/06 Primary

  Blood vessels · CPC title

• C25F3/16

  Polishing · CPC title