WO2014094652A1

WO2014094652A1 - Method for preparing biodegradable polymer frame

Info

Publication number: WO2014094652A1
Application number: PCT/CN2013/090097
Authority: WO
Inventors: 陈宝爱; 孟娟; 陈树国; 罗七一
Original assignee: 上海微创医疗器械（集团）有限公司
Priority date: 2012-12-21
Filing date: 2013-12-20
Publication date: 2014-06-26
Also published as: CN108016023A; CN106618820A; CN103876869A

Abstract

A method for preparing a biodegradable polymer frame comprises the following steps: 1) preparing a biodegradable polymer original tube (2) by using a biodegradable polymer material; 2) placing the original tube (2) in a tubular die (1), heating the original tube, and filling the original tube (2) with high-pressure gas, so that the original tube (2) can be highly oriented at the radial direction, and moreover, axially stretching the tube (2) along the axial direction of the tube (2), so that the tube (2) is oriented at the radial direction and the axial direction at the same time; 3) annealing the huffed tube (3) at the annealing temperature, to obtain the formed tube, the annealing temperature being higher than the transformation temperature (Tg) at which the polymer material is vitrified and being lower than the melting temperature (Tm) of the polymer material; and 4) preparing a biodegradable polymer frame (4) by using the formed tube. With the method, the short-time sustenance of the frame (4) is enhanced, so that fracture can be avoided; moreover, the internal stress of the tube can be effectively released, thereby improving the service life of the frame.

Description

Method for preparing biodegradable polymer scaffold

The present invention relates to a method of preparing a biodegradable polymer scaffold for medical use. Background technique

As an important device for the treatment of vascular stenosis, stents have been widely used in the field of cardiovascular diseases. For metal stents that are widely used in clinical practice, because they will remain in the human body after completing the treatment task, there are MRI or CT images that weaken the coronary arteries, interfere with surgical revascularization, hinder the formation of collateral circulation, and inhibit vascular integrity. Reshape and other defects. Based on these issues, biodegradable stents have attracted widespread attention as a possible alternative solution. The biodegradable stent is made of a degradable polymeric material or a metallic material. After implantation in the lesion, the biodegradable stent can support the blood vessels in a short period of time and achieve revascularization. After the treatment is completed, the biodegradable scaffold degrades into an organic substance that can be absorbed and metabolized by the human body in the human environment, and eventually the scaffold disappears. Common degradable polymer materials that can be used for stent preparation include polylactic acid, polyglycolic acid, polycaprolactone, etc.; common degradable metal materials that can be used for stent preparation are magnesium alloys, iron-based alloys, and the like. However, it has been found in the application process that the degradable metal material is difficult to ensure the effective support time of the stent because the degradation time is too fast. Biodegradable polymer materials (such as polylactic acid and its copolymers) have been approved by the US Food and Drug Administration as FDA-approved bioengineerable materials for humans. The research of biodegradable scaffolds with biodegradable polymer materials as raw materials is a hot research topic. Common biodegradable polymer materials (such as polylactic acid, polyglycolic acid, polycaprolactone) The mechanical properties of the other are relatively weak, and its Young's modulus is only about 0.1-4 GPa, and the strength is only 40-80 MPa. Due to the low mechanical strength of the material, the stents made of these materials have a small radial support force and are difficult to support the blood vessels. Moreover, the elastic range of these materials is larger than that of the conventional metal stent material, so that the prepared stent has a high rebound rate after expansion, which is also a big problem. In addition, these materials have small plastic deformation zones and poor toughness, which makes the stent prone to breakage and other adverse events during the expansion process. In addition, since the stent must be stored for a certain period of time after preparation, the short shelf life of the stent will also affect the application of the stent. In order to solve the problem of the supporting force and the toughness of the stent, US Pat. No. 8,012,402, inflates the original polymer tube for preparing the stent above the glass transition temperature to obtain a tube of high crystallinity, and the stent obtained by cutting the tube is realized. The radial orientation, so the support force is greatly improved. However, since the pipe does not form a perfect crystallization system during the short period of inflation, and there is much internal stress remaining inside the pipe after quenching after completion of inflation, the stent is easily broken. In addition, in the physical aging of the stent, the US Patent Document US20110260352 proposes to lower the stent after the inflated tube or the inflated tube is cooled to a temperature higher than room temperature and lower than the glass transition temperature of the material. To improve the crystallinity of the pipe and slow down the physical aging of the pipe during storage. However, it has been found through research that the technical advantages of the above treatment effects are not obvious and the physical aging of the material cannot be alleviated, and the stent treated by this method is still prone to breakage. Summary of the invention

In view of the above technical problems of the prior art, the object of the present invention is to develop a preparation method of a biodegradable polymer scaffold, so that the prepared biodegradable polymer scaffold has high immediate support force, is not easy to be broken, and the tube is The internal stress can be effectively released, thereby increasing the shelf life of the stent. According to the present invention, there is provided a method of preparing a biodegradable polymer scaffold comprising the steps of:

Step 1): preparing a biodegradable polymer raw tubing from a biodegradable polymer material;

Step 2): placing the raw pipe prepared in the step 1) into a tubular mold, heating the raw pipe, and injecting a high-pressure gas into the original pipe to follow a radial direction of the original pipe Inflating the original tubing in a direction such that an outer diameter of the inflated tubing is equal to an inner diameter of the tubular mold such that the tubing is capable of achieving a high orientation in a radial direction; and, prior to inflating the tubing in the radial direction After inflating the pipe along the radial direction or after inflating the pipe along the radial direction, axially stretching the pipe along the axial direction of the pipe to achieve the pipe at the diameter Simultaneous orientation of the direction and the axial direction;

Step 3): annealing the inflated tube at an annealing temperature to obtain a shaped tube, wherein the annealing temperature is higher than a glass transition temperature of the polymer material and lower than a melting temperature of the polymer material;

Step 4): The shaped tube obtained in the step 3) is prepared into the biodegradable polymer scaffold. Please note that "orientation" here refers to a technical term in the field of materials science, which means that the molecular chains in a certain material are preferentially arranged in a certain direction. Thus, the above "allowing the tube to be highly oriented in the radial direction" means that the molecular chains in the material of the tube are preferentially aligned substantially in the radial direction; the above-mentioned "implementing the tube in the radial direction and The simultaneous orientation of the axial direction means that the molecular chains within the material of the tube are preferentially aligned substantially in both the radial direction and the axial direction. In actual processing, the molecular chains in the material can generally be arranged substantially radially by expanding the tubes in their radial directions, and can be expanded by causing the tubes to expand in both their radial and axial directions. The expansion and stretching are such that the molecular chains in the material are aligned substantially in both the radial direction and the axial direction. The immediate support force of the degradable stent obtained by the above method of the present invention is high, It is prone to breakage, and the internal stress of the pipe is also effectively released due to the formation of a relatively perfect crystallization system, so it also has a positive effect on improving the shelf life of the stent. Preferably, the biodegradable polymer material in the step 1) is polylactic acid, polyglycolic acid, polycaprolactone, polydioxanone, polyanhydride, tyrosine polycarbonate or a copolymer thereof Or a blend. Depending on the materials selected, the degradation cycle of the stent in the human body can be from one month to three years, and the user can make any selection according to their respective needs. Preferably, the original pipe obtained in the step 1) is an amorphous pipe, and the amorphous pipe has a crystallinity of less than 20%. Preferably, the step 2) comprises the following steps:

Step a): placing the original pipe into the tubular mold having good thermal conductivity and being not easily deformed;

Step b): heating the original tube and the tubular mold to an orientation temperature that is higher than a glass transition temperature of the polymer material and lower than a melting temperature of the polymer material, and toward the interior of the original tube Injecting a high pressure gas to apply an expansion pressure to the original pipe to inflate the original pipe in a radial direction of the original pipe; and, before inflating the pipe along the radial direction, along the Simultaneously stretching the tube in the radial direction or axially stretching the tube along the axial direction of the tube after inflating the tube along the radial direction;

Step c): for the tube to maintain the expansion pressure in step b), the inflated tube and the tubular mold are rapidly cooled by water cooling or air cooling to lower the temperature below the glass transition temperature of the polymer material. Then, the expansion pressure is removed, and the inflated tubing is taken out. Preferably, the annealing in the step 3) means placing the inflated tube at the annealing temperature for a predetermined time, the predetermined time being 5 minutes to 24 hours. Preferably, in the step 3), the inflated tube is annealed The liner is placed in the interior of the inflated tubing and then removed from the interior of the inflated tubing after annealing is complete. The use of a core prevents the tube from shrinking during annealing. Preferably, in the step 4), the shaped tube is prepared by laser cutting to prepare the biodegradable polymer scaffold; or the shaped tube is cut into strips and then woven into the bio- Degradation of polymer scaffolds. Preferably, in the step b), the raw pipe is preheated at a preheating temperature before heating the raw pipe and the tubular die to the orientation temperature, the preheating temperature Higher than the glass transition temperature of the polymeric material. Preferably, the preheating temperature is lower than the glass transition temperature of the polymer material and the sum of 20 °C. In this temperature range, the growth of crystal nucleus in the polymer is favored, and the size growth of the crystal is disadvantageous, which is advantageous for forming a large number of small-sized crystals, which contributes to the improvement of the strength and toughness of the tube. Preferably, in the step b), heating is performed by a resistance wire wound on the tubular mold, or by using a high-pressure gas injected into the inside of the original pipe, thereby heating the original pipe and the The tubular mold is heated to the orientation temperature. Preferably, in the step b), the outer diameter ratio of the original pipe and the inflated pipe is between 1:1.5 and 1:5; the original pipe and the inflated pipe are The wall thickness ratio is between 1.5:1 and 5:1; and the length ratio of the original tubing to the inflated tubing is between 1:1 and 1:2. Preferably, in the step b), the expansion pressure is maintained for a predetermined time while maintaining the orientation temperature, the predetermined time being between 2 seconds and 10 minutes. This allows the tubing to be sufficiently oriented at the above temperatures and pressures to improve the mechanical properties of the final stent. Preferably, in the step c), the inflated tube and the tubular mold are The temperature is rapidly lowered to at least 20 ° C below the glass transition temperature of the polymeric material. By the preparation method of the present invention, the tube can be highly oriented in the radial and axial directions before being cut into a stent, so that the strength and toughness of the material in the radial direction and the axial direction are greatly improved. Moreover, through a certain period of annealing, a perfect crystallization system is formed, and the internal stress of the pipe is released, which effectively improves the support force and toughness of the stent immediately and after storage, and reduces the fracture phenomenon during the retraction and expansion of the stent. . According to the technical method of the present invention, the stent can be automatically loaded and the radial support force of the stent can be more than 120KPa after 3 months of storage, and the retraction rate after the stent is expanded can be controlled within 5%, and the stent is not expanded during the expansion process. It is prone to breakage. Moreover, the method of the present invention merely involves innovating the method of processing the stent without altering the raw material of the stent and thus has no effect on the biosafety of the stent. DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the description of the embodiments will be briefly described below. It is apparent that the drawings in the following description are only some of the specific embodiments described in the present application, and are not intended to limit the scope of the invention. It will be apparent to those skilled in the art that other embodiments and figures may be obtained in accordance with the embodiments of the present invention and the accompanying drawings without departing from the invention. Figure 1 is a schematic cross-sectional view along the longitudinal axis of the tubular mold and the original tubing showing the original tubing placed in the tubular mold.

Figure 2 is a schematic cross-sectional view along the longitudinal axis of the tubular mold and the inflated tubing, showing the condition after the original tubing is inflated, wherein the arrows in the figure indicate that the tubing is subjected to radial and axial directions, respectively. Force.

Figure 3 shows a structural view of the resulting stent of the present invention. Description of the reference signs: 1 represents a tubular mold, 2 represents the original tubing, 3 represents the inflated tubing, and 4 represents the final biodegradable polymer scaffold. detailed description

For a better understanding of the technical solutions in the present application, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings. It is apparent that the described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by a person of ordinary skill in the art based on the specific embodiments described herein, without departing from the inventive scope, should fall within the scope of the present invention. The present invention generally provides a method of preparing a biodegradable polymer scaffold for medical use. As mentioned earlier, the raw materials for common biodegradable stents are polymeric materials and degradable metallic materials. The degradation time of the degradable metal material is too fast, and it is difficult to ensure the effective support time of the stent. The biodegradable polymer material has a longer degradation time than the metal material. Therefore, the stent of the present invention is mainly constructed using a biodegradable polymer material. Preferred embodiments of the present invention are described in detail below with reference to Figs. 1 through 3. The present invention generally provides a method of preparing a biodegradable polymer scaffold comprising the following steps:

Step 1): preparing biodegradable polymer raw tubing from biodegradable polymer material 2;

Step 2): The original pipe 2 prepared in the step 1) is placed in the tubular mold 1 (as shown in FIG. 1, the original pipe 2 is inserted into the inner hole of the tubular mold 1), and the original pipe 2 is subjected to Heating, and injecting high pressure gas into the original pipe 2 to inflate the original pipe 2 in the radial direction of the original pipe 2 such that the outer diameter of the inflated pipe 3 is equal to the tubular die 1 Inner diameter (as shown in Figure 2), making the pipe radial The direction can achieve a high degree of orientation; and the tube can be axially stretched along the axial direction of the tube before inflating the tube along the radial direction, or can be inflated along the radial direction At the same time, the pipe is axially stretched along the axial direction of the pipe, or the pipe may be axially stretched along the axial direction of the pipe after inflating the pipe along the radial direction to realize the pipe in the pipe. Simultaneous orientation of the radial direction and the axial direction;

Step 3): annealing the inflated tube 3 at an annealing temperature to obtain a shaped tube, wherein the annealing temperature is higher than a glass transition temperature Tg of the polymer material and lower than a melting temperature Tm of the polymer material _;

Step 4): The shaped tube obtained in the step 3) is prepared into the biodegradable polymer scaffold. The final biodegradable polymer scaffold 4 is shown in FIG. The degradable stent obtained by the above method of the invention not only has a high immediate support force, is not easy to be broken, but also has an effective crystallization system, and the internal stress of the tube is also effectively released, so that the shelf life of the stent is positively improved. The role. Preferably, the biodegradable polymer material in the step 1) is polylactic acid, polyglycolic acid, polycaprolactone, polydioxanone, polyanhydride, tyrosine polycarbonate or a copolymer thereof Or a blend. Depending on the materials selected, the final biodegradable polymer scaffold 4 can be degraded in the human body for one month to three years, and the user can make any choice according to his own needs. Preferably, the original pipe 2 obtained in the step 1) is an amorphous pipe, and the amorphous pipe has a crystallinity of less than 20%. Preferably, the step 2) comprises the following steps:

Step a): placing the original pipe 2 into the tubular mold which is thermally conductive and is not easily deformed

1;

Step b): heating the original pipe 2 and the tubular mold 1 to an orientation temperature T which is higher than the glass transition temperature Tg of the polymer material and lower than the polymer material a melting temperature Tm, and injecting a high-pressure gas into the interior of the original pipe 2 to apply an expansion pressure to the original pipe 2 to inflate the original pipe 2 in a radial direction of the original pipe 2; The pipe is piped along the axial direction of the pipe before inflating the pipe along the radial direction, while inflating the pipe along the radial direction or after inflating the pipe along the radial direction Axial stretching

Step c): for the tube to maintain the expansion pressure in step b), the inflated tube 3 and the tubular mold 1 are rapidly cooled by water cooling or air cooling to cool the glass transition to the polymer material. The temperature Tg is below; then, the expansion pressure is removed, and the inflated tube 3 is taken out. Preferably, the annealing in the step 3) means that the inflated tube 3 is placed at the annealing temperature for a predetermined time, the predetermined time being 5 minutes to 24 hours. Preferably, in the step 3), a suitable size liner is placed inside the inflated tube 3 before annealing the inflated tube 3, and then the lining is completed after the annealing is completed. The core is taken out from the inside of the inflated tubing 3. The use of a core prevents the tubing from shrinking during the annealing process. Preferably, in the step 4), the shaped tube is prepared by laser cutting to prepare the biodegradable polymer holder 4; or the shaped tube is cut into strips and then woven into the living body. Degradable polymer scaffold 4. Preferably, in the step b), the raw pipe 2 is preheated at a preheating temperature T1 before the raw pipe 2 and the tubular die 1 are heated to the orientation temperature T, The preheating temperature T1 is higher than the glass transition temperature Tg of the polymer material. Preferably, the preheating temperature T1 is lower than the glass transition temperature Tg of the polymer material and

The sum of 20 °C. Gp, the preheating temperature T1>Tg, and the specific range of the preheating temperature T1 may be: Tg~Tg+20° C., where Tg is the glass transition temperature of the polymer material. In this temperature range, the growth of crystal nucleus in the polymer is favored, and the size growth of the crystal is disadvantageous, which is advantageous for forming a large number of small-sized crystals, which contributes to the improvement of the strength and toughness of the tube. Preferably, in the step b), a resistance wire is wound around the outer circumference of the tubular mold 1 to form a heater, which is heated by a resistance wire wound on the tubular mold 1; or the original is injected The high-pressure gas inside the pipe 2 has a high temperature, and is heated by a high-pressure gas injected into the inside of the original pipe 2, thereby heating the original pipe 2 and the tubular die 1 to the orientation temperature. Of course, the heating method of the present invention is not limited, and the above is merely illustrative. Preferably, in the step b), the original pipe 2 has a predetermined outer diameter, a predetermined wall thickness and a predetermined length, and the inflated pipe 3 has a corresponding outer diameter, wall thickness and length after inflation. The outer diameter ratio of the original pipe 2 and the inflated pipe 3 is between 1:1.5 and 1:5; the wall thickness ratio of the original pipe 2 and the inflated pipe 3 is 1.5:1 and Between 5:1; and the length ratio of the original tubing 2 and the inflated tubing 3 is between 1:1 and 1:2. Preferably, in the step b), the expansion pressure is maintained for a predetermined time while maintaining the orientation temperature T, the predetermined time being between 2 seconds and 10 minutes. This allows the tubing to be sufficiently oriented at the above temperatures and pressures to improve the mechanical properties of the final stent. Preferably, in said step c), said inflated tubing 3 and said tubular mould 1 are rapidly cooled to a temperature of at least 20 ° C below the glass transition temperature Tg of the polymeric material. Two examples of the preparation method of the present invention are described below using specific parameters. Example 1:

The polymer material of the original pipe 2 selected in the present example is a biodegradable polymer material polylactic acid. The polylactic acid particles were extruded to obtain a raw pipe 2 having an outer diameter of 1.5 mm and a wall thickness of 0.5 mm. The original pipe 2 was placed in a stainless steel tubular mold 1 having an inner diameter of 2.5 mm as shown in FIG. Polylactic acid raw tubing 2 is closed at one end and high pressure gas at the other end The road is connected. First, the original pipe 2 and the tubular mold 1 are heated to raise the temperature to 120 ° C, and then the original pipe 2 is filled with high-pressure nitrogen gas having a pressure of 200 psi, and the original pipe 2 is axially wound. Stretching, the stretching distance is 40mm. The original pipe 2 was prepared into a pipe having an outer diameter of 2.5 mm and a wall thickness of 0.15 mm under high temperature, high pressure and tensile conditions, that is, the inflated pipe 3, as shown in FIG. Thereafter, the entire system was rapidly cooled to room temperature, and then the pressure was released, and the inflated tube 3 was taken out. Finally, the inflated pipe 3 is placed on a metal core with an outer diameter of 2.2 mm, and annealed in an oven at 90 ° C for 5 minutes, and then the annealed formed pipe is laser-cut, and finally obtained as shown in FIG. 3 . The final biodegradable polymer scaffold 4. The prepared stent was crimped onto a suitable balloon, and the outer diameter of the stent after crimping was 1.0 mm. Then, the stent was expanded to an outer diameter of 3.0 mm in physiological saline at 37 ° C, and the stent was not broken during the expansion. After the balloon is withdrawn, the support force of the stent after expansion is measured to be greater than 100 kPa. At the same time, the stent prepared in the same manner was crimped onto a suitable balloon, and then vacuum-filled with an aluminum foil bag and placed at room temperature for 3 months. The stent was then removed, and the stent was expanded to an outer diameter of 3.0 mm in physiological saline at 37 ° C, and the stent was not broken during the expansion. After the balloon was withdrawn, the support force of the stent after expansion was measured, and as a result, the supporting force was greater than 100 kPa. The stent prepared in the same manner is firstly pressed into a suitable balloon, and then the stent that has not been stored and stored at room temperature for 3 months is separately delivered to the stenosis of the blood vessel, and the balloon is filled to expand the stent, thereby expanding the narrow blood vessel. During the distraction, no fracture of the stent was observed. After the balloon was withdrawn, angiography observed that the blood vessels were still stretched by the stent, and no adverse events of stent collapse occurred during the entire procedure. Two years later, the stent was not seen during clinical follow-up by intravascular ultrasound, indicating that the stent body material was completely degraded, and there was no restenosis or inflammatory reaction in the lesion site of the stent. Example two The polymer material of the original pipe 2 selected in the present example is a biodegradable polymer material polylactic acid-polyglycolic acid copolymer (PLGA) with a copolymerization ratio of 85:15. The copolymerized particles were injection-molded to obtain a raw pipe 2 having an outer diameter of 1.2 mm and a wall thickness of 0.3 mm. This raw pipe 2 was placed in a stainless steel tubular mold 1 having an inner diameter of 2.5 mm. The PLGA original pipe 2 is closed at one end and connected to a high pressure gas path at the other end. First, the original pipe 2 and the tubular mold 1 were heated to raise the temperature to 80 ° C, and then the original pipe 2 was charged with a high pressure helium gas having a pressure of 400 psi. The original pipe 2 was prepared into a pipe having an outer diameter of 2.5 mm and a wall thickness of 0.15 mm under conditions of high temperature and high pressure. The entire system was then rapidly cooled to 20 ° C and then depressurized to remove the inflated tubing 3 . Finally, the inflated pipe 3 is placed on a metal core with an outer diameter of 2.2 mm, and annealed in an oven at 80 ° C for 30 minutes, and then the annealed formed pipe is laser-cut into a sheet having a width of 0.2 mm. The sheet is woven to finally obtain a stent that meets the needs. The prepared stent is crimped onto a suitable balloon, and the outer diameter of the stent after pressing is 1. lmm. Then, the stent was expanded to an outer diameter of 2.5 mm in physiological saline at 37 ° C, and the stent was not broken during the expansion. The supporting force of the stent after expansion was measured, and as a result, the supporting force was about 140 kPa. At the same time, the stent prepared in the same manner was crimped onto a suitable balloon, and then vacuum-filled with an aluminum foil bag and placed at room temperature for 3 months. Then, the stent was taken out, and the stent was expanded to an outer diameter of 2.5 mm in physiological saline at 37 ° C, and the stent was not broken during the expansion. After the balloon was withdrawn, the support force of the stent after expansion was measured, and the support force was about 145 kpa. The stent prepared in the same manner is firstly pressed into a suitable balloon, and then the stent that has not been stored and stored at room temperature for 3 months is separately delivered to the stenosis of the blood vessel, and the balloon is filled to expand the stent, thereby expanding the narrow blood vessel. No fracture of the stent was observed during the opening process. After the balloon was withdrawn, angiography observed that the blood vessels were still stretched by the stent, and no adverse events of stent collapse occurred during the entire procedure. After 1.5 years, the stent was not seen during clinical follow-up by intravascular ultrasound, indicating that the stent body material was completely degraded, and the stent lesion was implanted. : There was no restenosis and inflammatory reaction. By the preparation method of the present invention, the tube can be highly oriented in the radial and axial directions before being cut into a stent, so that the strength and toughness of the material in the radial direction and the axial direction are greatly improved. Moreover, through a certain period of annealing, a perfect crystallization system is formed, and the internal stress of the pipe is released, which effectively improves the support force and toughness of the stent immediately and after storage, and reduces the fracture phenomenon during the retraction and expansion of the stent. . The stent prepared according to the technical method of the present invention can achieve the radial support force of the stent after 3 months of storage and can reach 120KPa or more, and the retraction rate after stent expansion can be controlled within 5%, and the stent does not expand during the expansion process. It is prone to breakage. Moreover, the method of the present invention merely involves innovating the method of processing the stent without altering the raw material of the stent and thus has no effect on the biosafety of the stent. The above description is only some specific embodiments of the present application. It should be noted that those skilled in the art can make various combinations or make some improvements and modifications to the above embodiments without departing from the principles and inventive concepts of the present invention. And variations are also considered to fall within the scope of the invention and the inventive concept.

Claims

1. A method for preparing a biodegradable polymer stent, including the following steps: Step 1): Prepare a biodegradable polymer original pipe from a biodegradable polymer material (2);

Step 2): Place the original pipe (2) prepared in step 1) into the tubular mold (1), heat the original pipe (2), and inject high pressure into the original pipe (2) Gas is used to blow the original pipe (2) along the radial direction of the original pipe (2), so that the outer diameter of the blown pipe (3) is equal to the inner diameter of the tubular mold (1), so that The pipe can achieve a high degree of orientation in the radial direction; and, before blowing the pipe along the radial direction, while blowing the pipe along the radial direction, or while blowing the pipe along the radial direction. Afterwards, axially stretching the pipe along the axial direction of the pipe to achieve simultaneous orientation of the pipe in the radial direction and the axial direction;

Step 3): Anneal the blown pipe (3) at an annealing temperature to obtain a shaped pipe, wherein the annealing temperature is higher than the glass transition temperature of the polymer material and lower than the melting temperature of the polymer material ;

Step 4): Prepare the biodegradable polymer scaffold (4) from the shaped pipe obtained in step 3).

2. The method for preparing a biodegradable polymer scaffold according to claim 1, characterized in that:

The biodegradable polymer material in step 1) is polylactic acid, polyglycolic acid, polycaprolactone, polydioxanone, polyanhydride, tyrosine polycarbonate or their copolymers or blends .

3. The preparation method of the biodegradable polymer scaffold according to claim 1, characterized in that:

The original pipe (2) obtained in step 1) is an amorphous pipe, and the crystallinity of the amorphous pipe is less than 20%.

4. The method for preparing a biodegradable polymer scaffold according to claim 1, characterized in that:

Said step 2) includes the following steps:

Step a): Put the original pipe (2) into the tubular mold (1) which has good thermal conductivity and is not easily deformed;

Step b): Heat the original pipe (2) and the tubular mold (1) to an orientation temperature that is higher than the glass transition temperature of the polymer material and lower than the melting temperature of the polymer material, and to High-pressure gas is injected into the interior of the original pipe (2) to apply expansion pressure to the original pipe (2) to inflate the original pipe along the radial direction of the original pipe (2); and, along the before inflating the tube in the radial direction, while inflating the tube in the radial direction, or after inflating the tube in the radial direction, axially conducting the tube along the axial direction of the tube. stretch; stretch

Step c): Maintain the expansion pressure in step b) for the pipe, and quickly cool down the blown pipe (3) and the tubular mold (1) by water cooling or air cooling to allow them to cool down to polymerization below the glass transition temperature of the material; then, remove the expansion pressure and take out the inflated pipe (3).

5. The preparation method of the biodegradable polymer scaffold according to any one of claims 1 to 4, characterized in that:

Annealing in step 3) refers to placing the blown pipe (3) at the annealing temperature for a predetermined period of time, and the predetermined time ranges from 5 minutes to 24 hours.

6. The method for preparing a biodegradable polymer scaffold according to claim 5, characterized in that:

In step 3), a lining core is placed inside the inflated pipe (3) before annealing the inflated pipe (3), and then the lining core is removed from the inflated pipe (3) after the annealing is completed. Take out the inside of the pipe (3) after the above inflation.

7. The preparation method of the biodegradable polymer scaffold according to any one of claims 1 to 4, characterized in that: In the step 4), the shaped pipe is prepared into the biodegradable polymer stent (4) by laser cutting; or the shaped pipe is cut into strip materials and then woven into the biodegradable polymer stent (4). Polymer scaffold (4).

8. The method for preparing a biodegradable polymer scaffold according to claim 4, characterized in that:

In step b), before heating the original pipe (2) and the tubular mold (1) to the orientation temperature, the original pipe (2) is preheated at a preheating temperature, The preheating temperature is higher than the glass transition temperature of the polymer material.

9. The method for preparing a biodegradable polymer stent according to claim 8, characterized in that:

The preheating temperature is lower than the glass transition temperature of the polymer material plus 20°C.

10. The preparation method of the biodegradable polymer scaffold according to claim 4, characterized in that:

In step b), heating is performed using a resistance wire wound around the tubular mold (1), or high-pressure gas injected into the interior of the original pipe (2) is used for heating, thereby heating the original pipe (2). 2) and the tubular mold (1) are heated to the orientation temperature.

11. The preparation method of the biodegradable polymer scaffold according to claim 4, characterized in that:

In step b), the outer diameter ratio of the original pipe (2) and the blown pipe (3) is between 1:1.5 and 1:5; the original pipe (2) and the The wall thickness ratio of the blown pipe (3) is between 1.5:1 and 5:1; and the length ratio of the original pipe (2) and the blown pipe (3) is between 1:1 and 1: between 2.

12. The preparation method of the biodegradable polymer scaffold according to claim 4, characterized in that:

In step b), while maintaining the orientation temperature, the expansion pressure The force is maintained for a predetermined time, the predetermined time being between 2 seconds and 10 minutes.

13. The preparation method of the biodegradable polymer scaffold according to claim 4, characterized in that:

In step c), the blown pipe (3) and the tubular mold (1) are rapidly cooled to at least 20V below the glass transition temperature of the polymer material.