Surgical sutures having increased strength
View Patent ↗The invention relates to increasing the strength of bio-absorbable surgical sutures. The invention allows for delayed bioabsorption of suture materials to allow maintenance of mechanical strength of the suture for example in ‘barbed’ form.
1. An absorbable suture comprising:
a core comprising a fast absorbing polymer;
a shell covering said core, wherein said shell comprises a stronger, more durable or slow-absorbing polymer,
wherein said shell comprises a chemical entity that inhibits ester hydrolysis, thereby slowing down bioabsorption and loss of mechanical strength, and wherein said chemical entity is a base.
2. The suture of claim 1 , wherein said shell comprises a barb structure.
3. The suture of claim 2 , wherein the strength of said barb structure is improved by treating with a supercritical fluid as compared to the strength of a non-treated barb structure.
4. The suture of claim 2 , wherein the rate of absorption of said barb structure is decreased by treating with a supercritical fluid as compared to the rate of absorption of a non-treated barb structure.
5. The suture of claim 1 , wherein said suture undergoes 50% breaking strength loss in greater than 21 days, and is absorbed in greater than 120 days.
6. The suture of claim 1 wherein said fast absorbing polymer is selected from DLPLA—poly(dl-lactide); LPLA—poly(l-lactide); PGA—polyglycolide; PDO—poly(dioxanone); PGA-TMC—poly(glycolide-co-trimethylene carbonate); PGA-LPLA—poly(l-lactide-co-glycolide); PGA-DLPLA—poly(dl-lactide-co-glycolide); LPLA-DLPLA—poly(l-lactide-co-dl-lactide); PDO-PGA-TMC—poly(glycolide-co-trimethylene carbonate-co-dioxanone.
7. The suture of claim 1 , wherein said slow absorbing polymer is poly(ε-caprolactone).
8. The suture of claim 1 wherein said core and shell materials are co-extruded.
9. The suture of claim 1 wherein said core is coated with said slow absorbing material to form said shell.
10. The suture of claim 1 , wherein the suture is treated with a supercritical fluid (SCF).
11. The suture of claim 10 , wherein said treating comprises immersing said suture into a supercritical fluid at a temperature greater than the glass transition temperature (Tg) of the material that forms the shell, yet lower than the melting temperature of said material.
12. The suture of claim 10 , wherein crystallinity in said suture is increased following treating with the supercritical fluid (SCF) as compared to the crystallinity of a non-treated suture.
13. The suture of claim 10 , wherein the suture comprises a crystalline domain on a surface of said suture.
14. The suture of claim 13 , wherein said shell comprises a barb structure and wherein the crystalline domain is on a surface of said barb.
15. The suture of claim 10 , wherein the crystallinity on a surface of the suture is greater than crystallinity of a non-surface of the suture.
16. The suture of claim 10 , wherein absorbability of said suture is 5% to 30% of the absorbability of a suture which is not treated with a supercritical fluid.
17. The suture of claim 1 , wherein the Tg of said shell is depressed in the presence of a compressed gas or supercritical fluid.
18. The suture of claim 1 further comprising a pharmaceutical agent.
19. The suture of claim 1 , wherein said base is a bronsted or lowery base.
20. The suture of claim 1 , wherein said base comprises an organic base.
21. The suture of claim 20 , wherein said organic base comprises an amine-containing molecule.
22. The suture of claim 1 , wherein the suture is without solvent residue despite employing a solvent in forming the suture.
23. The suture of claim 1 , wherein the suture comprises solvent-induced polymer crystallinity without solvent residue.
24. The suture of claim 1 , wherein the suture comprises solvent-induced polymer crystallinity without reaching or exceeding the melting temperature of the shell material.