# US 11,160,674 B2 · High performance bioabsorbable stent

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- Number: US 11,160,674 B2
- Document ID: US11160674B2
- Status: Granted
- Kind: B2
- Application number: 16/523,645
- Filed: 2019-07-26
- Published: 2019-11-14
- Granted: 2021-11-02
- Earliest claimed: 2017-01-30
- Assignees: Japan Medical Device Technology Co., Ltd.; Fuji Light Metal Co., Ltd.
- Applicants: Japan Medical Device Technology Co., LTD.; Fuji Light Metal Co., Ltd.
- Inventors: Makoto Sasaki; Yuki Koga; Yuki Okazawa; Hironori Ueda; Masashi Inoue
- Web page: https://patentgrep.com/patent/US11160674B2

## CPC

- A61F 2/90: characterised by a net-like or mesh-like structure
- A61L 31/022: {Metals or alloys}
- A61L 31/088: {Other specific inorganic materials not covered by A61L31/084 or A61L31/086}
- A61L 31/148: {Materials at least partially resorbable by the body}
- A61F 2/82: Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents (stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07)
- A61F 2/958: Inflatable balloons for placing stents or stent-grafts
- A61F 2210/0004: bioabsorbable
- A61F 2310/00011: Metals or alloys
- A61F 2310/00041: Magnesium or Mg-based alloys
- A61F 2310/00425: Coating made of magnesium or of Mg-based alloys
- A61L 31/06: obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds {(A61L31/041 takes precedence)}
- A61L 31/10: Macromolecular materials
- A61L 31/16: Biologically active materials, e.g. therapeutic substances {(A61L31/047 takes precedence)}
- A61L 2300/416: Anti-neoplastic or anti-proliferative or anti-restenosis or anti-angiogenic agents, e.g. paclitaxel, sirolimus
- A61L 2420/00: Materials or methods for coatings medical devices
- A61L 2420/08: Coatings comprising two or more layers
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)

## Abstract

To provide a stent excellent in deformability, capable of maintaining a radial force for a longer period of time, and having bioabsorbability and a method of producing the same. The bioabsorbable stent has a core structure including a magnesium alloy and a corrosion resistant layer on the core structure, wherein the core structure is formed from a magnesium alloy containing 90 mass % or more of Mg as a main component, Zn, Zr, and Mn as accessory components, and 30 ppm or less of unavoidable impurities selected from the group consisting of Fe, Ni, Co, and Cu, and the alloy excluding aluminum and at least one sort of rare earths selected from the group consisting of Sc, Y, Dy, Sm, Ce, Gd, and La; and the corrosion resistant layer containing magnesium fluoride as a main component with a hydrophilic smooth surface is formed on the core structure with a smooth surface.

## Claims

### Claim 1

A bioabsorbable stent having a core structure, wherein the core structure comprises a magnesium (Mg) alloy, wherein the stent further comprises a corrosion resistant layer on the core structure,
wherein the magnesium alloy contains 93 mass % or more of Mg as a main component, 1.0 to 2.0 mass % of zinc (Zn), 0.05 to 0.80 mass % of zirconium (Zr), and 0.05 to 0.40 mass % of manganese (Mn) as accessory components, and 30 ppm or less of unavoidable impurities selected from the group consisting of iron (Fe), nickel (Ni), cobalt (Co), and copper (Cu), and the alloy excluding aluminum and at least one sort of rare earth material selected from the group consisting of scandium (Sc), yttrium (Y), dysprosium (Dy), Samarium (Sm), cerium (Ce), gadolinium (Gd), and lanthanum (La); and
wherein the corrosion resistant layer contains magnesium fluoride as a main component, and wherein the corrosion resistant layer has a hydrophilic smooth surface with a surface roughness (Ra) of 0.20 μm or less.

### Claim 2 (depends on 1)

The bioabsorbable stent according to claim 1, wherein the magnesium alloy further contains 0.005 to 0.20 mass % of calcium (Ca).

### Claim 3 (depends on 1)

The bioabsorbable stent according to claim 1, wherein one of the unavoidable impurities selected from the group consisting of Fe, Ni, Co, and Cu is contained at a proportion of less than 10 ppm in the magnesium alloy.

### Claim 4 (depends on 1)

The bioabsorbable stent according to claim 1, wherein the hydrophilic smooth surface has a surface roughness of 0.10 μm or less.

### Claim 5 (depends on 1)

The bioabsorbable stent according to claim 1, wherein a biodegradable polymer layer is formed on at least a part of the hydrophilic smooth surface of the corrosion resistant layer.

### Claim 6 (depends on 5)

The bioabsorbable stent according to claim 5, wherein the stent is free from a gap between the corrosion resistant layer and the biodegradable polymer layer.

### Claim 7 (depends on 5)

The bioabsorbable stent according to claim 5, wherein the biodegradable polymer layer contains an intimal thickening inhibitor.

### Claim 8 (depends on 7)

The bioabsorbable stent according to claim 7, wherein the intimal thickening inhibitor is at least one member selected from the group consisting of sirolimus, everolimus, biolimus A9, zotarolimus, and paclitaxel.

### Claim 9

A method of producing a bioabsorbable stent having a core structure comprising a magnesium alloy, the comprising:
forming a core structure comprising a magnesium alloy containing 93 mass % or more of Mg as a main component, 1.0 to 2.0 mass % of Zn, 0.05 to 0.80 mass % of Zr, and 0.05 to 0.40 mass % of Mn as accessory components, and 30 ppm or less of unavoidable impurities selected from the group consisting of Fe, Ni, Co, and Cu, and excluding aluminum and rare earth selected from the group consisting of Sc, Y, Dy, Sm, Ce, Gd, and La;
carrying out electrolytic polishing of the core structure; and
forming a corrosion resistant layer having a hydrophilic smooth surface with a surface roughness (Ra) of 0.2 μm or less which contains magnesium fluoride as a main component by fluoridation processing of the core structure surface.

### Claim 10 (depends on 9)

The method of producing the bioabsorbable stent according to claim 9, wherein the electrolytic polishing is carried out until the core structure surface of comes to have a surface roughness (Ra) of 0.10 μm or less.