Biodegradable endoprostheses and methods for their fabrication
The disclosure provides biodegradable implantable devices such as a stent comprising a biodegradable polymeric wherein the polymeric material is treated to control crystallinity and/or Tg. The stent is capable to expand at body temperature from a crimped configuration to a deployed diameter and have sufficient strength to support a body lumen.
1. A degradable expandable stent, comprising:
a biodegradable polymeric material having a Tg of less than 44° C., said expandable stent at body temperature being expandable from a crimped configuration to a first expanded configuration and recoils from said first expanded configuration to a smaller configuration and being self expandable to a second configuration larger than the first expanded configuration after said recoil.
2. The expandable stent of claim 1 , wherein the polymeric material is treated to control one or more of crystallinity, T g , or molecular weight.
3. The expandable stent of claim 2 , wherein the polymeric material has a molecular weight between 30 kDa and 700 kDa.
4. The expandable stent of claim 2 , wherein the treatment comprises at least one of heating, heating and cooling, cooling, solvent removal, solvent incorporation, pressurization with gas, exposure to radiation, or expansion of the polymeric material to about 1 to 1.5 times a stent deployed diameter.
5. The expandable stent of claim 4 , wherein the treatment comprises heating and cooling.
6. The expandable stent of claim 5 , wherein the heating temperature is at about T g or below T g .
7. The expandable stent of claim 2 , wherein the polymeric material does not exhibit substantial phase separation after treatment.
8. The expandable stent of claim 2 , wherein the crystallinity is controlled at a level between 0 and 45%.
9. The expandable stent of claim 1 , wherein the stent comprises a tubular body.
10. The expandable stent of claim 1 , wherein the stent expands to the first expanded configuration without fracture and has sufficient strength to support a body lumen.
11. The expandable stent of claim 1 , wherein the polymeric material comprises at least one co-polymer.
12. The expandable stent of claim 11 , wherein the polymeric material comprises from 0.1 to 10% (by weight) of monomer or polymer.
13. The expandable stent of claim 12 , wherein the polymeric material comprises 1 to 100 micrograms of monomer or polymer per milligram of polymeric material.
14. The expandable stent of claim 12 , wherein the monomer or polymer is blended with the at least one co-polymer of the polymeric material.
15. The expandable stent of claim 12 , wherein the monomer or polymer is at least one of: lactide, glycolide, polylactide-co-glycolide, caprolactone, polylactide-co-caprolactone, or polyglycolide-co-caprolactone.
16. The expandable stent of claim 1 , wherein the polymeric material is selected from the group consisting of a polymer of lactic acid; a polymer of polyglycolic acid; a polymer of polylactic glycolic acid; a copolymer of a lactide and a glycolide; a copolymer of lactide and caprolactone; a copolymer of glycolide and caprolactone; a copolymer of a lactide, a glycolide and caprolactone; a blend of a lactide and a glycolidel a blend of lactide and caprolactone; a blend of a glycolide and caprolactone; and a blend of a lactide, a glycolide and caprolactone.
17. The expandable stent of claim 16 , wherein the polymeric material comprises 80-99% by weight of a lactide.
18. The expandable stent of claim 16 , wherein the polymeric material further comprises 1-20% by weight of a caprolactone.
19. The expandable stent of claim 16 , wherein the polymeric material further comprises 1-20% by weight of a glycolide.
20. The expandable stent of claim 1 , wherein the polymeric material further comprises between 0.1% and 10% (by weight) of at least one solvent.
21. The expandable stent of claim 1 , wherein the stent self expands prior to expansion to the first expanded configuration.
22. The expandable stent of claim 1 , wherein the recoil from the first expanded configuration is about 3 to 10%.
23. The expandable stent of claim 1 , wherein the stent has a nominal expanded configuration with a transverse dimension and the first expanded configuration has a transverse dimension that is 1 to 1.5 times the transverse dimension of the nominal expanded configuration.
24. The expandable stent of claim 23 , wherein transverse dimension of the nominal configuration ranges from 3 mm to 25 mm.
25. The expandable stent of claim 1 , wherein the stent is expanded to the first expanded configuration by balloon expansion.
26. The expandable stent of claim 1 , wherein the second configuration has a transverse dimension of at least 0.05 mm greater than a transverse dimension of the first expanded configuration.
27. The expandable stent as in claim 1 , wherein said stent self expands to the second configuration within 24 hours.
28. The expandable stent as in claim 1 , wherein the second configuration has a transverse dimension of at least 0.15 mm greater than a transverse dimension of the first expanded configuration.
29. The expandable stent of claim 1 , wherein the polymeric material has an elastic modulus ranging from 0.35 GPa to 1.5 GPa.
30. The expandable stent of claim 1 , comprising one or more radiopaque markers.
31. The expandable stent of claim 1 , comprising one or more polymeric coatings.
32. The expandable stent of claim 1 , comprising one or more metals or metal alloys.
33. The expandable stent of claim 1 , comprising one or more drugs.
34. The expandable stent of claim 1 , wherein the biodegradable polymeric material comprises a copolymer and the copolymer comprises 80-99% by weight of a lactide.
35. The expandable stent of claim 1 , wherein the stent has a nominal expanded configuration with a transverse dimension and the stent is patterned at 1 to 1.5 times the transverse dimension of the nominal expanded configuration.
36. The expandable stent of claim 1 , wherein the stent has a radial strength after expansion to the first expanded configuration, said radial strength increases by at least 5% within 15 days after expansion.
37. The expandable stent of claim 1 , wherein the stent has a radial strength after expansion to the first expanded configuration of at least 2 psi within 24 hours.
38. A degradable expandable stent, comprising:
a biodegradable polymeric material, wherein the polymeric material is treated to control crystallinity at a level between 25 and 45%, said expandable stent at body temperature being balloon expandable from a crimped configuration to a first expanded configuration and recoils from said first expanded configuration to a smaller configuration and being self expandable to a second configuration larger than the first expanded configuration after said recoil.
39. The degradable expandable stent of claim 38 , wherein the biodegradable polymeric material comprises a copolymer and the copolymer comprises 80-99% by weight of a lactide.
40. The degradable expandable stent of claim 38 , comprising one or more polymeric coatings.
41. The degradable expandable stent of claim 38 , wherein said expandable stent expands to said first expanded configuration without fracture and has sufficient strength to support a body lumen.
42. The degradable expandable stent of claim 38 , wherein the biodegradable polymeric material has a Tg of less than 44° C.
43. The degradable expandable stent of claim 38 , wherein the stent has a radial strength after expansion to the first expanded configuration, said radial strength increases by at least 5% within 15 days after expansion.
44. The degradable expandable stent of claim 38 , wherein the stent has a radial strength after expansion to the first expanded configuration of at least 2 psi within 24 hours.
45. The degradable expandable stent of claim 38 , wherein the recoil from said first expanded configuration comprises about 3%-10%.