Self-expanding stent and manufacturing method therefor
A self-expandable stent has sufficient radial force, has good bending properties, and recovers the shape for the diameter thereof to return from a diameter in a contracted state to a diameter before contraction around a body temperature (37° C.). The self-expandable stent includes a crosslinked polymer containing a constitutional unit (A) obtained from a monomer that constitutes a rigid biodegradable polymer when homopolymerized and a constitutional unit (B) obtained from a crosslinking agent, in which a content of the constitutional unit (B) is 15% by weight to 35% by weight with respect to a content of the constitutional unit (A).
1. A self-expandable stent comprising a crosslinked polymer consisting of a constitutional unit (A) obtained from a monomer that constitutes a rigid biodegradable polymer when homopolymerized and a constitutional unit (B) obtained from a crosslinking agent,
wherein a content of the constitutional unit (B) is 15% by weight to 35% by weight with respect to a content of the constitutional unit (A),
wherein the crosslinking agent is a monomer having two or more polymerizable unsaturated bonds, wherein the crosslinking agent includes pentaerythritol tetraacrylate, dipentaerythritol penta/hexa-acrylate, or a combination thereof.
2. The self-expandable stent according to claim 1 ,
wherein a Young's modulus of the crosslinked polymer is 500 N/mm 2 or more and a recovery rate thereof after 10 seconds is 65% or more.
3. The self-expandable stent according to claim 1 ,
wherein a Martens hardness of the crosslinked polymer is 50 N/mm 2 or more in a case where a loading-unloading test is carried out using a nanoindenter.
4. The self-expandable stent according to claim 1 ,
wherein the crosslinked polymer is obtained by polymerizing the crosslinking agent with a polymer containing the constitutional unit (A) obtained from the monomer that constitutes the rigid biodegradable polymer when homopolymerized and,
an absolute value of a difference between a solubility parameter value of the crosslinking agent and a solubility parameter value of the monomer that constitutes the rigid biodegradable polymer when homopolymerized is 5 (J/cm 3 ) 1/2 or less.
5. The self-expandable stent according to claim 1 ,
wherein the monomer that constitutes the rigid biodegradable polymer when homopolymerized contains at least one of lactic acid and glycolic acid.
6. The self-expandable stent according to claim 1 ,
wherein the content of the constitutional unit (B) is 25% by weight to 35% by weight with respect to the content of the constitutional unit (A).
7. The self-expandable stent according to claim 1 ,
wherein the monomer that constitutes the rigid biodegradable polymer when homopolymerized includes lactic acid, glycolic acid, or a combination thereof.
8. The self-expandable stent according to claim 1 ,
wherein the monomer that constitutes the rigid biodegradable polymer when homopolymerized includes poly L-lactic acid.
9. A method for producing a self-expandable stent, the method comprising:
polymerizing a polymer consisting of a constitutional unit (A) obtained from a monomer that constitutes a rigid biodegradable polymer when homopolymerized and a constitutional unit (B) obtained from a crosslinking agent having a content of 15% by weight to 35% by weight with respect to a content of the constitutional unit (A) to obtain a crosslinked polymer, wherein the crosslinking agent is a monomer having two or more polymerizable unsaturated bonds, wherein the crosslinking agent includes pentaerythritol tetraacrylate, dipentaerythritol penta/hexa-acrylate, or a combination thereof; and
producing the stent using the crosslinked polymer.
10. The method for producing a self-expandable stent according to claim 9 ,
wherein a weight average molecular weight of the polymer is 100,000 to 1,000,000.
11. The method for producing a self-expandable stent according to claim 9 ,
wherein the polymer and the crosslinking agent are polymerized under irradiation with an ultraviolet ray.
12. The method for producing a self-expandable stent according to claim 9 ,
wherein the polymer containing the constitutional unit (A) and the crosslinking agent are polymerized in the presence of a photopolymerization initiator.
13. The method for producing a self-expandable stent according to claim 9 ,
wherein the monomer that constitutes the rigid biodegradable polymer when homopolymerized includes lactic acid, glycolic acid, or a combination thereof.
14. The method for producing a self-expandable stent according to claim 9 ,
wherein the monomer that constitutes the rigid biodegradable polymer when homopolymerized includes poly L-lactic acid.
15. The self-expandable stent according to claim 1 , wherein the crosslinking agent is pentaerythritol tetraacrylate.
16. The method for producing a self-expandable stent according to claim 9 , wherein the crosslinking agent is pentaerythritol tetraacrylate.