RUBBER TOUGHENED BIORESORBABLE POLYMER PERIPHERAL SCAFFOLDS

• US 20130085563A1
• Filed: 10/03/2011
• Published: 04/04/2013
• Est. Priority Date: 10/03/2011
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Inventors: Stankus, John, Wang, Yunbing, Trollsas, Mikael, Hossainy, Syed Faiyaz Ahmed, Ngo, Michael H., Davalian, Dariush
• Granted Patent: US 9,180,228 B2
• Time in Patent Office: Days
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2210/0057 stretchable
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61L 31/041 Mixtures of macromolecular compounds
• CPC Class Codes: A61L 31/129 containing macromolecular fillers
• CPC Class Codes: A61L 31/141 Plasticizers
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body

Abstract

Bioabsorbable scaffolds are disclosed with a rigid polymer component and a rubbery polymer component. The rubbery polymer component is miscible, partially miscible, or immiscible with the rigid polymer component.

Claims

1. A stent comprising a scaffold formed from a polymer tube

configured for being crimped to a balloon,

the scaffold having a pattern of interconnected elements and

the scaffold having an expanded diameter when expanded from a crimped state by the balloon,

wherein the scaffold attains greater than about 80% of its diameter after being crushed to at least 50% of its expanded diameter;

and

wherein the scaffold has a radial stiffness greater than 0.3 N/mm and

wherein the scaffold is made from a composition including a rigid bioresorbable polymer component having a glass transition temperature (Tg) greater than 37 deg C. and a rubbery polymer component having a Tg less than ambient temperature, wherein the rubbery polymer component is between 5 and 25 wt % of the composition.

2. The stent of claim 1, wherein rubbery polymer component is polyethylene glycol (PEG) having a weight average molecular weight (Mw) of 20 kDa or less.

3. The stent of claim 1, wherein the rubbery polymer component is an amphiphilic block copolymer selected from the group consisting of PLLA-PEG-PLLA, PDLA-PEG-PDLA, PLGA-PEG-PLGA, PEG-PLLA, PEG-DL-PLA, and PEG-PLGA.

4. The stent of claim 1, wherein the rigid polymer component is poly(L-lactide) (PLLA) and the rubbery polymer component is selected from the group consisting of polyhydroxyalkanoates (PHA), poly(4-hydroxybutyrate) (P4HB), poly(8-caprolactone) (PCL), poly(trimethylene carbonate) (PTMC), poly(butylene succinate) (PBS), and poly(p-dioxanone) (PDO).

5. A stent comprising a scaffold made from a bioresorbable composition comprising a bioresorbable rigid polymer component having a Tg greater than 37 deg C. and a rubbery polymer component having a Tg less than ambient temperature, wherein the rubbery polymer component is partially or completely miscible in the rigid polymer component, wherein the Mw of the rubbery polymer component is 20 kDa or less.

6. The stent of claim 5, wherein the rubbery polymer component is PEG and the PEG is 5 to 10 wt % of the scaffold.

7. The stent of claim 5, wherein the rigid polymer component is PLLA and the rubbery polymer component is selected from the group consisting of PHA, P4HB, PCL, PTMC, PBS, and PDO.

8. The stent of claim 5, wherein the rubbery polymer component is completely miscible in the rigid polymer component.

9. The stent of claim 5, wherein the Mw of the rubbery polymer component is 2 kDa or less.

10. A stent comprising a scaffold made from a bioresorbable composition comprising a bioresorbable random copolymer including a bioresorbable rigid polymer having a Tg greater than 37 deg C. and a rubbery polymer having a Tg less than ambient temperature, wherein the rubbery polymer is 5 to 25 mol % of the scaffold.

11. The stent of claim 10, wherein the number average molecular weight (Mn) of the copolymer is 200 to 600 kDa.

12. The stent of claim 10, wherein the rigid polymer is PLLA and the rubbery polymer is poly(L-lactide-co-ε

-caprolactone).

13. The stent of claim 10, wherein random copolymer is a copolymer of PLLA and a polymer selected from the group consisting of PHA, P4HB, PCL, PTMC, PBS, and PDO.

14. A stent comprising a scaffold made from a bioresorbable composition comprising a bioresorbable rigid polymer component having a Tg greater than 37 deg C. and a rubbery polymer component having a Tg less than ambient temperature, wherein the Mw of the rubbery polymer component is less than 50% of the Mw of the bioresorbable rigid polymer component, wherein the bioresorbable rigid polymer component is 75 to 95 wt % of the scaffold and the rubbery polymer component is 5 to 25 wt % of the scaffold.

15. The stent of claim 14, wherein the Mw of the rigid polymer component is 100 to 300 kDa.

16. The stent of claim 14, wherein the rubbery polymer component is a rubbery polymer and is blended with the bioresorbable rigid polymer component.

17. The stent of claim 14, wherein the rubbery polymer component is a rubbery block of a block copolymer further including a rigid polymer block blended with the bioresorbable rigid polymer component.

18. The stent of claim 14, wherein the bioresorbable rubbery polymer component is a rubbery block of a block copolymer and the rigid polymer component is a rigid polymer block of the block copolymer.

19. The stent of claim 14, wherein the rubbery polymer component is PCL which is blended with PLLA, the rigid polymer component.

20. The stent of claim 14, wherein the rubbery polymer component is PCL and the rigid polymer component is PLLA.

21. A method of fabricating a stent comprising:

providing a tube made of a bioresorbable polymer composition including a matrix phase and dispersed phase composed of domains distributed throughout the matrix phase, wherein the matrix phase comprises a bioresorbable rigid polymer with a Tg greater than 37 deg C. and the dispersed phase comprises a rubbery polymer with a Tg less than ambient temperature;

elongating the tube along its cylindrical axis at least 50%, wherein the elongation elongates the domains in the direction of the cylindrical axis; and

fabricating a scaffold from the tube after the elongating step, wherein the composition of the scaffold includes elongated domains.

22. The method of claim 21, wherein the temperature of the tube during elongation is greater than the Tg of the rubbery polymer and less than the Tg of the bioresorbable rigid polymer.

23. The method of claim 21, wherein the temperature of the tube during elongation is greater than the Tm of the rubbery polymer, greater than the Tg of the bioresorbable rigid polymer, and less than the Tm of the bioresorbable rigid polymer.

24. The method of claim 21, further comprising radially expanding the tube after the elongating step and fabricating the scaffold from the radially expanded tube.

25. A stent comprising a scaffold made from a bioresorbable polymer composition including a matrix phase and a dispersed phase composed of domains distributed throughout the matrix phase, wherein the matrix phase comprises a bioresorbable rigid polymer with a Tg greater than 37 deg C. and the dispersed phase comprises a crosslinked rubbery polymer which is crosslinked with the rigid polymer.

26. The stent of claim 25, wherein the bioresorbable rigid polymer is about 75 to 95 wt % of the scaffold and the rubbery polymer is 5 to 25 wt % of the scaffold.

27. A method of fabricating a stent comprising:

providing a tube or a scaffold made of a bioresorbable polymer composition including a matrix phase and a dispersed phase composed of domains distributed throughout the matrix phase, wherein the matrix phase comprises a bioresorbable rigid polymer with a Tg greater than 37 deg C. and the dispersed phase comprises a rubbery polymer with a Tg less than ambient temperature;

irradiating the tube or the scaffold to induce crosslinking of the rubbery polymer and the rubbery polymer to the rigid polymer; and

if the tube is irradiated, fabricating a scaffold from the tube after the irradiating step.

28. The method of claim 27, wherein the rubbery polymer includes reactive functional groups and the crosslinking is induced at the reactive functional groups upon exposure to radiation.

29. The method of claim 27, wherein the composition includes a crosslinking agent that induces the crosslinking when the tube or the scaffold is irradiated.

30. The method of claim 27, wherein a temperature of the tube or the scaffold during irradiation is between the Tg of the bioresorbable rubbery polymer and the Tg of the bioresorbable rigid polymer.

31. The method of claim 27, wherein a temperature of the tube or the scaffold during irradiation is greater than the Tm of the rubbery polymer and the Tg of the bioresorbable rigid polymer and less than the Tm of the bioresorbable rigid polymer.