Granted Patent B2

US 9,050,389 · App. 13/331,683 · Granted Jun 9, 2015

Abstract

Claims (47)

1. A method for the manufacture of a biocompatible, corrosion-inhibiting protective surface layer on a medical implant comprising a magnesium-based alloy, the method comprising:

placing an implant comprising a magnesium-based alloy into a reactor chamber;

exposing at least part of a surface of said implant to an atmosphere comprising humid carbon dioxide, wherein the concentration of the carbon dioxide is at least 50%, and wherein the atmosphere is modified by the addition of gaseous hydrocarbons comprising methane or propane, to produce a coating on the surface of the implant comprising a magnesium carbonate of the formula x MgCO 3 .y Mg (OH) 2 , whereby x+y=1;

removing the implant from the reactor chamber; and

drying the surface of the implant.

2. The method according to claim 1 , wherein the atmosphere has a relative humidity of at least 30%.

3. The method according to claim 2 , wherein said relative humidity is 100%.

4. The method according to claim 2 , wherein the temperature in said reactor chamber is in the range of 10° C. to 50° C.

5. The method according to claim 2 , wherein the temperature in said reactor chamber is in the range of 20° C. to 30° C.

6. The method according to claim 2 , wherein said relative humidity is at least about 90%.

7. The method according to claim 1 , wherein the concentration of carbon dioxide is at least about 90%.

8. The method according to claim 1 , wherein the gaseous hydrocarbons are added in an amount of less than 10% of the total gas content.

9. The method according to claim 1 , wherein the atmosphere is activated by heating up the atmosphere without heating up the implant.

10. The method according to claim 9 , wherein the atmosphere is activated by heating up the atmosphere using microwaves.

11. The method according to claim 1 , wherein the pressure in said reactor exceeds atmospheric pressure.

12. The method according to claim 11 , wherein the pressure in said reactor chamber is in the range of about 5 to about 60 bar.

13. The method according to claim 1 , wherein water is added to the reactor chamber before placing the implant into the reactor chamber.

14. The method according to claim 1 , wherein the pressure in said reactor corresponds essentially to atmospheric pressure.

15. The method according to claim 1 , wherein said magnesium-based implant is coated over a time period lasting about 24 hours to about 720 hours.

16. The method according to claim 1 , wherein said drying is effected at 80° C. to 130° C.

17. The method according to claim 1 further comprising:

treating the surface of the implant with supercritical carbon dioxide prior to exposing at least part of the surface of the implant to the atmosphere.

18. The method according to claim 1 , wherein said drying is effected for about 10 minutes to about 30 minutes.

19. A method for the manufacture of a biocompatible, corrosion-inhibiting protective surface layer on a medical implant comprising a magnesium-based alloy, the method comprising:

placing an implant comprising a magnesium-based alloy into a reactor chamber wherein the pressure in said reactor exceeds atmospheric pressure;

exposing at least part of a surface of said implant to an atmosphere comprising humid carbon dioxide to produce a coating on the surface of the implant comprising a magnesium carbonate of the formula x MgCO 3 .y Mg (OH) 2 , whereby x +y =1;

removing the implant from the reactor chamber; and

drying the surface of the implant.

20. The method according to claim 19 , wherein the atmosphere has a relative humidity of at least 30%.

21. The method according to claim 20 , wherein the atmosphere is modified by the addition of hydrogen gas and/or gaseous hydrocarbons.

22. The method according to claim 21 , wherein the gaseous hydrocarbons comprise methane or propane.

23. The method according to claim 21 , wherein the hydrogen gas and/or gaseous hydrocarbons are added in an amount of less than 10% of the total gas content.

24. The method according to claim 20 , wherein said relative humidity is 100%.

25. The method according to claim 20 , wherein the temperature in said reactor chamber is in the range of 10° C. to 50° C.

26. The method according to claim 20 , wherein the temperature in said reactor chamber is in the range of 20° C. to 30° C.

27. The method according to claim 20 , wherein said relative humidity is at least about 90%.

28. The method according to claim 19 , wherein the concentration of the carbon dioxide is at least 50%.

29. The method according to claim 28 , wherein the concentration of the carbon dioxide is at least about 90%.

30. The method according to claim 19 , wherein the atmosphere is activated by heating up the atmosphere without heating up the implant.

31. The method according to claim 30 , wherein the atmosphere is activated by heating up the atmosphere using microwaves.

32. The method according to claim 19 , wherein the pressure in said reactor chamber is in the range of about 5 to about 60 bar.

33. The method according to claim 19 , wherein water is added to the reactor chamber before placing the implant into the reactor chamber.

34. The method according to claim 19 , wherein said magnesium-based implant is coated over a time period lasting about 24 hours to about 720 hours.

35. The method according to claim 19 , wherein said drying is effected at 80° C. to 130° C.

36. The method according to claim 19 further comprising:

treating the surface of the implant with supercritical carbon dioxide prior to exposing at least part of the surface of the implant to the atmosphere.

37. The method according to claim 19 , wherein said drying is effected for about 10 minutes to about 30 minutes.

Assignments (6)