CN109172074B

CN109172074B - Degradable stent with shell-core structure and preparation method thereof

Info

Publication number: CN109172074B
Application number: CN201811185896.XA
Authority: CN
Inventors: 卢立中; 欧阳俊雄
Original assignee: Orbusneich Medical Shenzhen Co ltd
Current assignee: Orbusneich Medical Shenzhen Co ltd
Priority date: 2018-10-11
Filing date: 2018-10-11
Publication date: 2020-08-25
Anticipated expiration: 2038-10-11
Also published as: CN109172074A

Abstract

The invention discloses a shell-core structure degradable stent and a preparation method thereof, wherein the degradable stent is a tubular structure and comprises a stent body; the bracket body is provided with frameworks and hollow structures formed among the frameworks; wherein, the skeleton includes: the inner shell layer is provided with a hollow tubular shape; the hollow tubular middle core layer is coated outside the inner shell layer, and comprises an outer core layer and a mesh-structured inner core layer coated inside the outer core layer; and a hollow tubular outer shell layer coated outside the middle core layer; wherein the inner core layer adopts high molecular polylactic acid with the molecular weight of 700-800 kDa; the outer core layer adopts macromolecular polylactic acid with the molecular weight of 200-300 kDa. The degradable support with the shell-core structure is easy to spray and process by clamping and holding the saccule, the condition of fracture of the support wire does not occur in the processing process and after the processing is finished, and the processing difficulty and the risk of fracture of the support are greatly reduced under the condition that the degradable support has good degradation performance.

Description

Degradable stent with shell-core structure and preparation method thereof

Technical Field

The invention belongs to the technical field of medical instruments, relates to a degradable stent, and particularly relates to a shell-core structure degradable stent and a preparation method thereof.

Background

The stent implantation operation is an important means for clinically treating ischemic cardiovascular diseases, but the stent which is generally used in the market at present is still the third generation metal drug eluting stent, and the stent material comprises 316L stainless steel, cobalt-chromium alloy, titanium alloy and the like. Once implanted, such metal stents are accompanied by foreign bodies and vascular tissues for life, and patients usually take antiplatelet drugs for a long time to prevent thrombosis. In addition, because the metal stent stimulates the vascular wall for a long time, the vascular endothelial dysfunction is caused, local chronic inflammation and hyperproliferation of new tissues are caused, and restenosis in the stent, even late thrombus is easily formed.

In view of the above drawbacks, the concept of degradable stents as a substitute for metal stents was proposed by researchers several years ago. The degradable stent provides mechanical support in the early stage after implantation and gradually degrades automatically in the later stage without radial support until the stent disappears completely. After the stent is completely degraded, the stimulation to the target blood vessel, the local inflammatory reaction caused by the stimulation and the excessive hyperplasia of the intima of the blood vessel do not exist any more, and the restenosis and the thrombus after the stent is implanted can be effectively reduced.

The scientific concept of degradable stents is well established, namely, support is provided in the early stage, and the support function is gradually degraded until the support function disappears. However, it is not easy to satisfy both conditions. To achieve the above two objectives, the industry mainly studies three major biodegradable stent systems, and the analysis of advantages and disadvantages is as follows:

the degradable magnesium alloy stent and the iron alloy stent encounter bottlenecks in the application field of the degradable stent due to poor biocompatibility and uncontrollable hard injury of degradation speed. Degradable polymer stents have been extensively studied in this field because of their excellent biocompatibility and controllable degradation rate, but a balance of mechanical properties and degradation rate remains a difficult point that a single polymer material cannot overcome.

The degradable stent system using a single polymer as a material is difficult to satisfy both mechanical properties and degradable properties, mainly because the mechanical properties and the degradable properties are two spears existing at the same time originally, and it is difficult to use a single polymer as a material to achieve both the mechanical properties and the degradable properties, which is ultimately the limitation of the material. For example, in the case of pure polylactic acid PLLA applied to a degradable stent, to achieve a degradation rate matching with vascular repair, the molecular weight should be controlled between 150kDa and 200kDa, and in the case of such molecular weight, even if the wall thickness is controlled to 150 microns, radial support is difficult to compare favorably with the conventional metal drug-coated stent, and moreover, the wall thickness of a normal metal stent is less than 100 microns, so the competitiveness of the degradable stent is greatly reduced. If the other extreme is considered, in order to meet the requirement of mechanical property, the molecular weight is increased, the degradation time is very long, the high molecular weight also greatly increases the difficulty of processing the stent, and increases the risk of fracture of the stent.

Disclosure of Invention

The invention aims to provide a degradable scaffold with a shell-core structure and a preparation method thereof, which can simultaneously meet mechanical properties and degradable properties aiming at the defect that a single polymer cannot give consideration to mechanical properties, degradable properties and processability in the prior art.

Compared with the traditional scheme that only a plurality of materials can be adopted, the scheme for simultaneously meeting the requirements is achieved through a proper physical processing way and a unique bracket structure. The structure of the degradable scaffold with the shell-core structure provided by the invention can optimize the radial mechanical supporting force to a certain extent, and effectively reduce the fracture of the scaffold in the processing or using process. The invention also provides a preparation method of the shell-core structure degradable stent, which greatly reduces the processing difficulty of the stent and the risk of stent fracture under the condition of ensuring that the degradable stent has good degradation performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a degradable stent with a shell-core structure, which is a tubular structure and comprises a stent body, wherein the stent body is provided with skeletons and hollow structures formed between the skeletons; wherein the skeleton comprises:

the inner shell layer is provided with a hollow tubular shape;

the hollow tubular middle core layer is coated outside the inner shell layer, and comprises an outer core layer and a mesh-structured inner core layer coated inside the outer core layer; and

and the hollow tubular outer shell layer is coated outside the middle core layer.

Further, the inner core layer adopts high molecular polylactic acid with the molecular weight of 700-800 kDa; the outer core layer adopts macromolecular polylactic acid with the molecular weight of 200-300 kDa.

Furthermore, the molecular orientation of the high molecular polylactic acid in the inner core layer is in an amorphous state, and the crystallinity of the high molecular polylactic acid is 20-30%.

Further, the thickness of the inner core layer is 10-20 μm.

More preferably, the polymer polylactic acid of the outer core layer fills the grid of the inner core layer, and polymer layers of 5-15 μm are formed on the inner side and the outer side of the inner core layer respectively.

Further preferably, the intermediate core layer has a thickness of 20 to 50 μm and an overall molecular orientation in an amorphous state.

Furthermore, the outer shell layer and the inner shell layer both adopt high molecular polylactic acid with the molecular weight of 150-200kDa, and the crystallinity of the high molecular polylactic acid is 40-50%.

Further, the thickness of the outer shell layer and the inner shell layer is 30-40 μm respectively.

Further, the total thickness of the bracket body is 80-130 μm.

Further, the outer shell layer and the inner shell layer are transparent.

Further, the inner core layer is semitransparent, and the outer core layer is transparent.

Furthermore, the hollowed-out structures are S-shaped, V-shaped or W-shaped structures and are arranged in a staggered mode.

Further preferably, the skeleton of the middle core layer 120 is provided with a plurality of dividing gaps 160, and the dividing gaps 160 are located at the connection positions of two adjacent hollow structures 150.

Further, the width of the dividing gap 160 is 5 to 30 μm.

The second aspect of the present invention provides a method for preparing a degradable scaffold with a shell-core structure, comprising the following steps:

step 1, providing an inner core layer with a hollow pipe cavity, and cutting the inner core layer into a net-shaped structure;

step 2, forming an outer core layer on the inner core layer of the reticular structure, wherein the inner core layer is arranged in the outer core layer to form a middle core layer with the inner core layer and the outer core layer;

step 3, respectively providing an inner shell layer with a hollow pipe cavity and an outer shell layer with a hollow pipe cavity, respectively sleeving the inner shell layer and the outer shell layer on the inner side and the outer side of the middle nuclear layer, and melting the outer shell layer, the middle nuclear layer and the inner shell layer into a whole;

and 4, cutting the pipe fused into a whole into a support body with a framework and a hollow structure.

Further, in the step 1, the inner core layer is extruded and molded by adopting high molecular weight polylactic acid with the molecular weight of 700-800kDa, the molecular orientation is in an amorphous state, and the crystallinity is 20-30%.

Further, in the step 1, the inner core layer is cut into a net-shaped structure by adopting a laser cutting mode.

Further, in step 2, the inner core layer is disposed within the outer core layer 122 in a wrapping extrusion manner.

Further preferably, in the step 2, the outer core layer is formed by extrusion of a polymer polylactic acid with a molecular weight of 200-300kDa, and the overall molecular orientation of the middle core layer is in an amorphous state.

Further, in the step 3, the outer shell layer and the inner shell layer are both extruded and molded by adopting the macromolecular polylactic acid with the molecular weight of 150-200kDa, and are subjected to heat setting and blowing treatment.

Further preferably, the polymer chains in the outer shell layer and the inner shell layer after the heat setting and blowing treatment in step 3 are oriented radially, and the crystallinity thereof is 40-50%.

Furthermore, in step 3, the tube with the outer shell layer, the middle core layer and the inner shell layer is placed in a mold and melted into a whole under high temperature and high pressure, wherein the melting temperature is 155-.

Further, the pipe melted into a whole in the step 4 is cut into the stent body in a femtosecond cutting mode.

By adopting the technical scheme, compared with the prior art, the invention has the following technical effects:

(1) the radial support of the degradable scaffold with the shell-core structure can reach more than 15 psi; the maximized molecular chain radial orientation and high crystallinity approaching 50% of the inner and outer shell layers are favorable for mechanical properties; the high molecular weight polylactic acid of the middle core layer greatly increases the radial supporting strength; the stent wire opening angle selects the maximum radial support;

(2) the stent is easy to spray and process by clamping and holding the saccule, the fracture of the stent wire does not occur in the processing process and after the processing is finished, and the processing difficulty of the stent and the risk of the fracture of the stent are greatly reduced under the condition of ensuring that the degradable stent has good degradation performance;

(3) the polylactic acid with the inner and outer shell layers of 150-kDa and 200-kDa is confirmed to be suitable for the processing requirement of the degradable stent, is clamped below the glass transition temperature and is expanded under the water environment of 37 ℃ to be difficult to break, and the microscopic treatment at the corners of the stent wire can effectively prevent mechanical breakage;

(4) the scaffold has no mechanical property loss within three months after being implanted; the stent polymer starts to degrade 3-6 months after implantation and finishes degrading within 3 years.

Drawings

FIG. 1 is a three-layer tube structure view of the degradable scaffold of the shell-core structure according to the present invention;

FIG. 2 is a cross-sectional structural view of a three-layered tube for preparing a degradable scaffold of a shell-core structure according to the present invention;

FIG. 3 is a structural view of a longitudinal cross-section of a three-layered tube for preparing a degradable scaffold of a shell-core structure according to the present invention;

FIG. 4 is a perspective view of the degradable scaffold of the shell-core structure of the present invention;

FIG. 5 is a front view structural view of the degradable scaffold of the shell-core structure of the present invention;

FIG. 6 is a rear view structural view of the degradable scaffold of the shell-core structure of the present invention;

FIG. 7 is a sectional view of a cross-section A-A of the degradable scaffold of the shell-core structure shown in FIG. 6;

FIG. 8 is a sectional structural view of a B-B section of the degradable scaffold of the shell-core structure shown in FIG. 6;

FIG. 9 is a partial enlarged structural view of a portion C of the degradable scaffold of the shell-core structure shown in FIG. 4;

FIG. 10 is a side view structural drawing of the degradable scaffold of the shell-core structure of the present invention;

FIG. 11 is a cross-sectional structural view of a D-D section of the degradable scaffold of the shell-core structure shown in FIG. 10;

FIG. 12 is a cross-sectional structural view of section E-E of the degradable scaffold of the shell-core structure shown in FIG. 10;

FIG. 13 is a partial enlarged structural view of a portion F of the degradable scaffold of the shell-core structure shown in FIG. 12;

FIG. 14 is a microstructure diagram of the upper corner of a degradable scaffold of a shell-core structure according to the invention;

wherein the reference symbols are:

100-stent body, 110-outer shell layer, 120-middle core layer, 121-inner core layer, 122-outer core layer, 130-inner shell layer, 140-skeleton, 150-hollow structure and 160-segmentation gap.

Detailed Description

The invention provides a degradable bracket with a shell-core structure, and the three-layer structure can optimize the radial mechanical supporting force to a certain extent and effectively reduce the fracture of the bracket in the processing or using process. The invention also provides a preparation method of the shell-core structure degradable stent, which greatly reduces the processing difficulty of the stent and the risk of stent fracture under the condition of ensuring that the degradable stent has good degradation performance. Compared with the traditional scheme that only a plurality of materials can be adopted, the scheme for simultaneously meeting the requirements is achieved through a proper physical processing way and a unique bracket structure.

The present invention will be described in detail and specifically with reference to the following examples to facilitate better understanding of the present invention, but the following examples do not limit the scope of the present invention.

as shown in fig. 4 to 12, the present embodiment provides a shell-core structural degradable stent, which is a tubular structure and includes a stent body 100, wherein the stent body 100 has skeletons 140 and hollow-out structures 150 formed between the skeletons 140; wherein the skeleton 140 includes: an inner shell layer 130 having a hollow tubular shape; the hollow-out tubular middle core layer 120 is coated outside the inner shell layer 130, and the middle core layer 120 comprises an outer core layer 122 and a mesh-structured inner core layer 121 coated inside the outer core layer 122; and a hollow tubular outer shell 110 covering the middle core layer 120. The inner core layer 121 adopts high molecular polylactic acid with the molecular weight of 700-800 kDa; the outer core layer 122 adopts the high molecular weight polylactic acid with the molecular weight of 200-300kDa, and the high molecular weight polylactic acid of the middle core layer 120 greatly increases the radial supporting strength of the stent.

The degradable stent with the shell-core structure is easy to spray and process by clamping and holding the saccule, and the condition of stent wire fracture can not occur in the processing process and after the processing is finished. The scaffold should not have a loss of mechanical properties within three months after implantation. The stent polymer starts to degrade within 3-6 months after being implanted and finishes degrading within 3 years; can meet the mechanical property and the degradability of the degradable stent at the same time.

In one embodiment, the polymeric polylactic acid in the inner core layer 121 is molecularly oriented in an amorphous state with a crystallinity of 20 to 30%; preferably 22-28%; more preferably 24-26%. And the thickness of the inner core layer 121 is 10-20 μm; preferably, the inner core layer 121 has a thickness of 12-17 μm; more preferably, the inner core layer 121 has a thickness of 15 μm, which reduces the occurrence of stent breakage during processing or use to some extent.

In one embodiment, as shown in fig. 11 to 12, the polymer polylactic acid of the outer core layer 122 fills the lattice of the inner core layer 121 and forms polymer layers of 5 to 15 μm, preferably 6 to 12 μm, and more preferably 10 μm, on the inner and outer sides of the inner core layer 121, respectively. This results in the intermediate core layer 120 having a thickness of 20 to 50 μm, preferably 25 to 45 μm, and more preferably 35 μm, and an amorphous overall molecular orientation.

In one embodiment, the outer shell layer 110 and the inner shell layer 130 both use a high molecular weight polylactic acid with molecular weight of 150-200kDa, and the crystallinity is 40-50%, and the maximized radial orientation of molecular chains and high crystallinity close to 50% of the outer shell layer 110 and the inner shell layer 130 are favorable for mechanical properties. And the 150-kDa polylactic acid adopted by the outer shell layer 110 and the inner shell layer 130 is confirmed to be suitable for the processing requirement of the degradable stent, and is not easy to break when being held below the glass transition temperature and being expanded under 37-DEG water environment, and the micro-treatment at the corners of the stent filaments can effectively prevent mechanical breakage.

In one embodiment, the outer shell layer 110 and the inner shell layer 130 each have a thickness of 30-40 μm; preferably, the outer shell layer 110 and the inner shell layer 130 have a thickness of 32-36 μm, respectively; more effectively, the outer shell layer 110 and the inner shell layer 130 each have a thickness of 35 μm. As above, the total thickness of the stent body 100 is 80-130 μm; preferably, the total thickness of the stent body 100 is 90-110 μm. The diameter of the stent body 100 is 2.5-4.0 mm; preferably, the stent body 100 has a diameter of 2.65-3.42 mm; more preferably, the stent body 100 has a diameter of 3.0 mm. Under the condition of wall thickness of 80-130 μm, the radial support of the cut degradable stent with the diameter of 2.5-4.0mm reaches more than 15 psi.

In one embodiment, the outer shell layer 110 and the inner shell layer 130 are both transparent. The inner core layer 121 is translucent and the outer core layer 122 is transparent.

In one embodiment, the hollow 150 has an S-shaped, V-shaped or W-shaped structure. As shown in fig. 4-6, a W-shaped configuration is preferred. The skeletons 140 are arranged in a staggered way, so that the skeletons have good degradability and processability on the basis of ensuring certain mechanical properties.

In one embodiment, as shown in fig. 12 to 13, a plurality of dividing gaps 160 are disposed on the skeleton of the middle core layer 120, and the dividing gaps 160 are located at the connection positions of two adjacent hollow structures 150; preferably, the dividing gaps 160 are spaced along the axis of the middle core layer 120 on the skeleton. The split gaps 160 cut by a laser cutting machine are arranged on the skeleton of the middle core layer 120 of the degradable stent with the shell-core structure, and the width of each split gap 160 is 5-30 μm, preferably 10-25 μm, and more preferably 20 μm, so that the contact area of the degradable stent and blood is increased, and the dissolution rate of the degradable stent is increased.

As a preferred embodiment of the present invention, there is provided a method for preparing a degradable scaffold with a shell-core structure, as shown in fig. 1 to 3, specifically comprising the following steps:

step 1, providing an inner core layer 121 with a hollow pipe cavity, and cutting the inner core layer 121 into a net-shaped structure;

step 2, forming an outer core layer 122 on the inner core layer 121 of the mesh structure, wherein the inner core layer 121 is arranged in the outer core layer 122, and forming an intermediate core layer 120 with the inner core layer 121 and the outer core layer 122;

step 3, respectively providing an inner shell layer 130 with a hollow pipe cavity and an outer shell layer 110 with a hollow pipe cavity, respectively sleeving the inner shell layer 130 and the outer shell layer 110 on the inner side and the outer side of the middle nuclear layer 120, and melting the outer shell layer 110, the middle nuclear layer 120 and the inner shell layer 130 into a whole;

and 4, cutting the pipe fused into a whole into the bracket body 100 with the framework 140 and the hollow structure 150.

In one embodiment, the inner core layer 121 in step 1 is formed by extrusion molding of a high molecular weight polylactic acid with molecular weight of 700-800kDa, and the molecular orientation is amorphous, and the crystallinity is 20-30%. In step 1, the inner core layer 121 is cut into a mesh structure by a laser cutting method.

In one embodiment, in step 2, the inner core layer 121 is disposed inside the outer core layer 122 in a wrapping extrusion manner, and the polymer of the outer core layer 122 fills the cut-off portion of the inner core layer 121 and forms a polymer layer of 5-15 μm inside and outside the inner core layer 121.

In one embodiment, in step 2, the outer core layer 122 is formed by extrusion of a polymer polylactic acid with a molecular weight of 200-300kDa, the overall molecular orientation of the middle core layer 120 is in an amorphous state, and the radial supporting strength of the stent is greatly increased by the polymer polylactic acid of the middle core layer 120.

In a preferred embodiment, in step 3, the outer shell layer 110 and the inner shell layer 130 are both formed by extrusion molding of a high molecular weight polylactic acid with a molecular weight of 150-200kDa, and subjected to heat setting and blowing treatment. The polymer chains in the outer shell layer 110 and the inner shell layer 130 after the heat setting and blowing treatment in step 3 are oriented radially, and the crystallinity thereof is 40-50%.

In a preferred embodiment, in step 3, the tube having the outer shell layer 110, the intermediate core layer 120 and the inner shell layer 130 is placed in a mold and melted into a whole at high temperature and high pressure, wherein the melting temperature is 155-180 ℃ and the pressure is over 600 psi.

In a preferred embodiment, the tube melted into one in step 4 is cut into the stent body 100 by femtosecond cutting, as shown in fig. 4-6.

In the degradable stent with the shell-core structure of the embodiment, the microstructure of the stent body 100, that is, the microstructure of the stent wire corner on the scaffold 140, is as shown in fig. 14, and this stent structure can effectively prevent the stent wire from being broken during the processing and use while optimizing the radial support of the stent.

The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Any equivalent modifications and substitutions to those skilled in the art are also within the scope of the present invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.

Claims

1. A shell-core structure degradable stent is a tubular structure and comprises a stent body (100), and is characterized in that the stent body (100) is provided with skeletons (140) and hollow structures (150) formed among the skeletons (140); wherein the skeleton (140) comprises:

an inner shell layer (130) with a hollow tubular shape;

the hollow-out tubular middle core layer (120) is coated outside the inner shell layer (130), and the middle core layer (120) comprises an outer core layer (122) and a reticular inner core layer (121) coated inside the outer core layer (122); and

the hollow tubular outer shell layer (110) is coated outside the middle core layer (120);

the inner core layer (121) adopts high molecular polylactic acid with the molecular weight of 700-800 kDa; the outer core layer (122) adopts macromolecular polylactic acid with the molecular weight of 200-300 kDa; the thickness of the inner core layer (121) is 10-20 μm;

the polymer polylactic acid of the outer core layer (122) is filled in the grid of the inner core layer (121), and polymer layers with the thickness of 5-15 mu m are respectively formed on the inner side and the outer side of the inner core layer (121);

the outer shell layer (110) and the inner shell layer (130) both adopt high molecular polylactic acid with molecular weight of 150-200kDa, and the crystallinity of the high molecular polylactic acid is 40-50%.

2. The shell-core structured degradable scaffold according to claim 1, wherein the molecular orientation of the polymeric polylactic acid in the inner core layer (121) is amorphous with a crystallinity of 20-30%.

3. The shell-core structured degradable scaffold according to claim 1, wherein the intermediate core layer (120) has a thickness of 20-50 μm and an overall molecular orientation in an amorphous state.

4. The shell-core structured degradable scaffold according to claim 1, characterized in that the thickness of the outer shell layer (110) and the inner shell layer (130) is 30-40 μm each.

5. The shell-core structured degradable scaffold according to claim 4, wherein the total thickness of the scaffold body (100) is 80-130 μm.

6. The shell-core structured degradable stent according to claim 4 wherein the stent body (100) has a diameter of 2.5-4.0 mm.

7. The shell-core structured degradable scaffold according to claim 1, wherein the outer shell layer (110) and the inner shell layer (130) are both transparent.

8. The shell-core structured degradable scaffold according to claim 1, wherein said inner core layer (121) is translucent and said outer core layer (122) is transparent.

9. The shell-core structured degradable scaffold according to claim 1, wherein said hollowed-out structures (150) are S-shaped, V-shaped or W-shaped structures, and are arranged in a staggered manner.

10. The shell-core structure degradable scaffold according to claim 9, wherein the skeleton of the middle core layer (120) is provided with a plurality of dividing gaps (160), and the dividing gaps (160) are located at the connection position of two adjacent hollow structures (150).

11. The shell-core structured degradable scaffold according to claim 10, wherein the width of the segmentation gap (160) is 5-30 μm.

12. A preparation method of a degradable scaffold with a shell-core structure is characterized by comprising the following steps:

step 1, providing an inner core layer (121) with a hollow pipe cavity, and cutting the inner core layer (121) into a net-shaped structure;

step 2, forming an outer core layer (122) on the inner core layer (121) of the reticular structure, wherein the inner core layer (121) is arranged in the outer core layer (122), and an intermediate core layer (120) with the inner core layer (121) and the outer core layer (122) is formed;

step 3, respectively providing an inner shell layer (130) with a hollow pipe cavity and an outer shell layer (110) with a hollow pipe cavity, respectively sleeving the inner shell layer (130) and the outer shell layer (110) on the inner side and the outer side of the middle nuclear layer (120), and melting the outer shell layer (110), the middle nuclear layer (120) and the inner shell layer (130) into a whole;

and 4, cutting the pipe fused into a whole into a support body (100) with a framework (140) and a hollow structure (150).

13. The method for preparing the degradable scaffold with the shell-core structure as claimed in claim 12, wherein the core layer (121) in step 1 is formed by extrusion of a high molecular weight polylactic acid with molecular weight of 700-800kDa, the molecular orientation is amorphous, and the crystallinity is 20-30%.

14. The method for preparing the shell-core structure degradable scaffold according to claim 12, wherein the inner core layer (121) is cut into a net structure by laser cutting in step 1.

15. The method for preparing a shell-core structured degradable scaffold according to claim 12, wherein the inner core layer (121) is disposed inside the outer core layer (122) in a wrapping extruded manner in step 2.

16. The method for preparing the degradable scaffold with the shell-core structure as claimed in claim 15, wherein the outer core layer (122)) is extruded and molded by using a high molecular weight polylactic acid with molecular weight of 200-300kDa in step 2, and the whole molecular orientation of the middle core layer (120) is amorphous.

17. The method for preparing the degradable scaffold with the shell-core structure as claimed in claim 12, wherein the outer shell layer (110) and the inner shell layer (130) in step 3 are both extruded and molded by using a high molecular weight polylactic acid with molecular weight of 150-200kDa and are subjected to heat setting and blowing treatment.

18. The method for preparing the degradable scaffold having a shell-core structure according to claim 17, wherein the polymer chains in the outer shell layer (110) and the inner shell layer (130) after the heat setting and blowing treatment in step 3 are oriented radially, and the crystallinity thereof is 40-50%.

19. The method for preparing the degradable scaffold having a shell-core structure according to claim 12, wherein the step (3) comprises placing the tube having the outer shell layer (110), the intermediate core layer (120) and the inner shell layer (130) in a mold, and melting them into a whole at high temperature and high pressure, wherein the melting temperature is 155 ℃ and the pressure is over 600 psi.

20. The method for preparing a shell-core structured degradable scaffold according to claim 12,

and (4) cutting the pipe fused into a whole in the step (4) into a stent body (100) in a femtosecond cutting mode.