CN113288509B

CN113288509B - Preparation method and device of PTFE (polytetrafluoroethylene) covered stent

Info

Publication number: CN113288509B
Application number: CN202110573807.4A
Authority: CN
Inventors: 陈珊珊; 娄秋凤; 倪振华; 张倩
Original assignee: Yingmai Medical Technology Shanghai Co ltd
Current assignee: Yingmai Medical Technology Shanghai Co ltd
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2023-08-22
Anticipated expiration: 2041-05-25
Also published as: CN113288509A

Abstract

The application relates to the field of preparation of covered stents and discloses a preparation method and device of a PTFE covered stent. The method comprises the steps of: (01) preparing a sacrificial layer on the surface of the basic bracket; (02) Simultaneously electrospinning at the inner and outer surfaces of the base bracket to form an inner PTFE electrospun wire mesh and an outer PTFE electrospun wire mesh respectively; (03) And sintering the electrostatic spinning base bracket, removing the sacrificial layer, so that the electrostatic spinning silk screen of the inner side PTFE and the electrostatic spinning net shape of the outer side PTFE are arranged on the coating film on the inner surface and the outer surface of the base bracket, and finally obtaining the PTFE coated bracket. The preparation method of the PTFE coated stent provided by the application is simple and efficient, and the coated porosity is high and accurate and controllable.

Description

Preparation method and device of PTFE (polytetrafluoroethylene) covered stent

Technical Field

The application relates to a preparation method and a preparation device of a medical instrument, in particular to a preparation method and a preparation device of a PTFE (polytetrafluoroethylene) covered stent.

Background

Cardiovascular diseases are very common diseases in clinic, such as vascular stenosis, hemangiomas, arterial dissection, etc. Stent implantation is an effective means of treating cardiovascular disease. The metal bracket with the reticular structure has good compliance and is widely applied. However, the stent gap is prone to cell proliferation, platelet adhesion, etc., which can easily lead to restenosis. Therefore, it is necessary to add a coating film to the self-expanding stent, thereby accelerating endothelialization of the inner surface of the stent and preventing thrombosis. In another aspect, polytetrafluoroethylene, PTFE, is a desirable coating material. However, the process for producing the PTFE coating is complicated due to the characteristics of chemical inertness, super lubrication and the like of Polytetrafluoroethylene (PTFE).

In the prior art, an inner layer PTFE coating and an outer layer PTFE coating are respectively prepared through 2 times of electrostatic spinning, a connecting layer is added between the two layers of the PTFE coatings, and the process is complex. And the inner layer coating or the outer layer coating is subjected to 2 times of high-temperature sintering, and the pore space in the coating can be partially collapsed, so that the porosity of the coating is reduced and uncontrollable. A method for preparing a double-layer PTFE stent-graft is disclosed in patent CN109806042 a: and (3) electrostatic spinning a PTFE tube on the rotating shaft, sleeving the support on the PTFE tube after sintering, manufacturing a connecting layer outside the PTFE tube and the support, electrostatic spinning a second layer of PTFE tube outside the connecting layer, and finally combining the connecting layer with an inner PTFE film and an outer PTFE film through sintering. Since the connection force between the PTFE particles and the second layer PTFE tube formed by electrospinning is reduced when the PTFE tubes are sintered to form the PTFE tube, it is necessary to add a thermoplastic connection layer to improve the connection force between the PTFE particles and the second layer PTFE tube. However, the bonding effect is still lower than that of PTFE direct bonding, and in addition, the thickness of the stent is increased under the same medical effect after the connecting layer is added, so that the compliance of the covered stent is reduced.

There is a need for a simple and efficient method and apparatus for preparing PTFE coated stents.

Disclosure of Invention

The application aims to provide a preparation method and a device of a PTFE coated stent, and the preparation method of the PTFE coated stent is simple, efficient, high in coated porosity and accurate and controllable.

The application discloses a preparation method of a PTFE covered stent, which comprises the following steps:

(01) Preparing a sacrificial layer on the surface of a basic bracket;

(02) Simultaneously electrospinning at the inner and outer surfaces of the base bracket to form an inner PTFE electrospun wire mesh and an outer PTFE electrospun wire mesh respectively;

(03) Sintering the electrospun basic bracket to remove the sacrificial layer, so that the inner PTFE electrospun silk screen and the outer PTFE electrospun silk screen are arranged on the coating film on the inner surface and the outer surface of the basic bracket, and finally obtaining the PTFE coated bracket.

In a preferred embodiment, the thickness of the sacrificial layer is 0.01mm to 0.05mm.

In a preferred embodiment, the sacrificial layer is prepared from an aqueous solution of a water-soluble polymeric material.

In a preferred embodiment, before the sacrificial layer is prepared in the step (01), a film is laid on the other side of the base bracket opposite to the side on which the sacrificial layer is to be provided, so as to prevent the water-soluble polymer material aqueous solution from entering the surface of the other side of the base bracket.

In a preferred example, the water-soluble polymer material is polyethylene oxide PEO or polyvinyl alcohol PVA, and the weight average molecular weight is 105-107 g/mol.

In a preferred embodiment, the concentration of the aqueous solution of the water-soluble polymer material is 0.1wt% to 2wt%.

In a preferred embodiment, in step (02), the electrospinning is performed using an aqueous PTFE electrospinning solution comprising PTFE nanoparticles having a particle size of 10nm to 100nm.

In a preferred embodiment, the concentration of PTFE nanoparticles in the PTFE electrospun aqueous solution is 10wt% to 40wt%.

In a preferred embodiment, the PTFE electrospun aqueous solution further comprises a blending agent, wherein the concentration of the blending agent is 0.5wt% to 10wt%.

In a preferred example, the blending agent is polyethylene oxide or polyvinyl alcohol, and the weight average molecular weight is 105-107 g/mol.

In a preferred embodiment, in step (02) the inner and outer surfaces of the base scaffold are simultaneously electrospun by a preparation device comprising:

the first spray head (1), the second spray head (5) and a high-voltage power supply,

the positive electrode of the high-voltage power supply is used for being electrically connected with the first spray head 1 and the second spray head 5, the negative electrode of the high-voltage power supply is used for being electrically connected with the basic bracket 4,

the first spray head 1 is used for spraying PTFE electrostatic spinning aqueous solution on the outer surface of the basic bracket under the action of a high-voltage electric field;

the second spray head 5 is used for spraying PTFE electrostatic spinning aqueous solution on the inner surface of the basic bracket under the action of a high-voltage electric field.

In a preferred embodiment, in step (03), the sintering temperature is 300-400 ℃.

The application also discloses a device for preparing the PTFE covered stent, which comprises: a first nozzle 1, a second nozzle 5 and a high-voltage power supply;

In one preferred embodiment of the present application,

the first spray head 1 is arranged perpendicular to the axis of the base bracket;

the second spray head 5 extends away from the inner wall of the foundation bracket perpendicularly to the axis of the foundation bracket, then extends along the axial direction of the foundation bracket, and finally extends towards the inner wall of the foundation bracket perpendicularly to the axis of the foundation bracket.

In a preferred embodiment, the device further comprises a clamping assembly 8, wherein the clamping assembly 8 is used for clamping one end of the base bracket and driving the base bracket to rotate, and is configured to enable PTFE electrostatic spinning aqueous solution to be uniformly sprayed on the inner surface and the outer surface of the base bracket in the circumferential direction.

In a preferred embodiment, the device further comprises a first support 2, a second support 7;

the first supporting piece 2 and the second supporting piece 7 are horizontally arranged, the first spray head 1 is movably arranged on the first supporting piece 2, and the second spray head 5 is movably arranged on the second supporting piece 7.

The embodiment of the present application has the following technical effects.

1. The preparation method of the PTFE coated stent adopts a one-time electrostatic spinning method to directly manufacture the PTFE coated film on the inner surface and the outer surface of the stent, and the double-layer coated film is integrally formed, so that the process is simple and efficient.

2. The PTFE coating film manufactured by the preparation method of the PTFE coating film bracket is sintered at high temperature only once, the porosity of the coating film is as high as more than 85 percent, and the method is accurate and controllable.

3. On the premise of maintaining the medical performance, the thickness of the covered stent is reduced, and the compliance is improved. The numerous technical features described in the description of the present application are distributed among the various technical solutions, which can make the description too lengthy if all possible combinations of technical features of the present application (i.e., technical solutions) are to be listed. In order to avoid this problem, the technical features disclosed in the above summary of the application, the technical features disclosed in the following embodiments and examples, and the technical features disclosed in the drawings may be freely combined with each other to constitute various new technical solutions (which should be regarded as having been described in the present specification) unless such a combination of technical features is technically impossible. For example, in one example, feature a+b+c is disclosed, in another example, feature a+b+d+e is disclosed, and features C and D are equivalent technical means that perform the same function, technically only by alternative use, and may not be adopted simultaneously, feature E may be technically combined with feature C, and then the solution of a+b+c+d should not be considered as already described because of technical impossibility, and the solution of a+b+c+e should be considered as already described.

Drawings

FIG. 1 is a schematic flow chart of a method of making a PTFE coated stent according to one embodiment of the present application;

FIG. 2 is a schematic structural view of an apparatus for preparing a PTFE coated stent according to an embodiment of the present application;

FIG. 3 is a schematic view of a scanning electron microscope of a PTFE coated stent prepared according to one embodiment of the present application;

reference numerals illustrate:

the spray head comprises a first spray head 1, a first supporting piece 2, a first insulating baffle 3, a foundation bracket 4, a second spray head 5, a heating component 6, a clamping component 8, a second supporting piece 7 and a second insulating baffle 9.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be understood by those skilled in the art that the claimed application may be practiced without these specific details and with various changes and modifications from the embodiments that follow.

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

As shown in fig. 1, a first embodiment of the present application relates to a method for preparing a PTFE stent graft, comprising the steps of:

(01) And preparing a sacrificial layer on the surface of the basic bracket.

Alternatively, in one embodiment, the sacrificial layer is prepared by water-soluble polymer material aqueous solution, the water-soluble polymer material is polyethylene oxide PEO and polyvinyl alcohol PVA, the weight average molecular weight is 105-107 g/mol, the concentration of the water-soluble polymer material aqueous solution is 0.1-2 wt%, and the thickness of the prepared sacrificial layer is 0.01-0.05 mm.

Optionally, in one embodiment, before the sacrificial layer is prepared in step (01), a film is laid on the other side of the base bracket opposite to the side to be provided with the sacrificial layer, so as to prevent the water-soluble polymer material aqueous solution from entering the surface on the other side of the base bracket.

(02) And simultaneously carrying out electrostatic spinning on the inner surface and the outer surface of the basic bracket to respectively form an inner PTFE electrostatic spinning silk screen and an outer PTFE electrostatic spinning silk screen.

Optionally, in one embodiment, in step (02), the electrostatic spinning is performed using an aqueous PTFE electrostatic spinning solution, where the aqueous PTFE electrostatic spinning solution includes PTFE nanoparticles having a particle size of 10nm to 100nm, and the concentration of the PTFE nanoparticles in the aqueous PTFE electrostatic spinning solution is 10wt% to 40wt%.

Optionally, in one embodiment, the PTFE electrospun aqueous solution further comprises a blending agent, wherein the concentration of the blending agent is 0.5wt% to 10wt%, the blending agent is polyethylene oxide or polyvinyl alcohol, and the weight average molecular weight is 105 to 107g/mol.

(03) And sintering the electrospun basic stent, removing the sacrificial layer, and placing the inner PTFE electrospun silk screen and the outer PTFE electrospun silk screen on the coating film on the inner surface and the outer surface of the basic stent, thereby finally obtaining the PTFE coated stent.

Optionally, in one embodiment, in step (03), the sintering temperature is 300-400 ℃.

A second embodiment of the present application is directed to an apparatus for preparing a PTFE covered stent, the apparatus comprising: a first nozzle 1, a second nozzle 5 and a high-voltage power supply;

the positive pole of the high-voltage power supply is used for being electrically connected with the first spray head 1 and the second spray head 5, the negative pole of the high-voltage power supply is used for being electrically connected with the basic bracket 4,

Alternatively, in one embodiment, the first spray head 1 is arranged perpendicular to the axis of the base bracket.

The second spray head 5 extends away from the inner wall of the base bracket perpendicularly to the axis of the base bracket, then extends along the axial direction of the base bracket, and finally extends towards the inner wall of the base bracket perpendicularly to the axis of the base bracket.

Optionally, in one embodiment, the apparatus further includes a clamping assembly 8, wherein the clamping assembly 8 is used for clamping one end of the base support and driving the base support to rotate, and is configured to uniformly spray the PTFE electrospun aqueous solution on the inner surface and the outer surface of the base support in a circumferential direction.

Optionally, in one embodiment, the device further comprises a first support 2, a second support 7. The first supporting piece 2 and the second supporting piece 7 are horizontally arranged, the first spray head 1 is movably arranged on the first supporting piece 2, and the second spray head 5 is movably arranged on the second supporting piece 7.

The application aims to solve the problems of complex preparation process, uncontrollable tectorial membrane porosity caused by 2 times of high-temperature sintering and the like of a PTFE double-layer tectorial membrane bracket, and adopts a method of one-time electrostatic spinning and one-time high-temperature sintering to prepare the PTFE tectorial membrane on the inner surface and the outer surface of a basic bracket. In a specific embodiment, a sacrificial layer is firstly prepared on the inner surface of a basic bracket, then the basic bracket is horizontally fixed in an electrostatic spinning device, electrostatic spinning is simultaneously carried out on the inner surface and the outer surface of the basic bracket through two spinning nozzles right above the basic bracket and inside the basic bracket, finally the sacrificial layer and the blending agent in the silk are removed at one time through sintering, and simultaneously PTFE particles in the inner silk and the outer silk are fused and bonded together to form a coating film which is respectively arranged on the inner layer and the outer layer. The method can realize one-step molding of the double-layer coating, the preparation process is simple and efficient, the porosity of the coating is as high as more than 85%, and the coating is accurate and controllable.

A first embodiment of the present application relates to a method of making a PTFE covered stent. The preparation method of the PTFE covered stent comprises the following steps:

step 01, preparing a sacrificial layer on the surface of the basic bracket:

in order to prevent the spinning fiber from penetrating through the holes of the support and being unable to form a film on the surface of the base support during electrostatic spinning on the surface of the base support, an ultrathin sacrificial layer needs to be prepared on the base support, and the sacrificial layer needs to be removed in the subsequent treatment process of the film without affecting the film forming. Preferably, the thickness of the sacrificial layer is between 0.01mm and 0.05mm. Preferably, the sacrificial layer is prepared by an aqueous solution of a water-soluble polymer material. More preferably, the water-soluble polymer material is polyethylene oxide PEO, polyvinyl alcohol PVA, and the weight average molecular weight is 10 ⁵ ～10 ⁷ g/mol. Further, the concentration of the water-soluble polymer material aqueous solution is 0.1wt% to 2wt%.

The sacrificial layer is prepared on the inner surface of the basic bracket. Firstly, a film, such as a polyethylene PE film, a silicon rubber film and the like, is flatly wound on the outer surface of the basic bracket, and is tightly attached to the outer surface of the basic bracket, so that the water solution of the sacrificial layer (namely the water solution of the water-soluble polymer material) is prevented from entering the outer surface of the basic bracket. And horizontally placing the foundation bracket, and adding a sacrificial layer aqueous solution into the foundation bracket. Slowly rotating the basic support to uniformly spread the sacrificial layer solution on the inner surface of the basic support, and then rapidly rotating the basic support until the solvent of the sacrificial layer aqueous solution is completely volatilized. And removing the film wound outside the basic bracket to obtain the basic bracket with the sacrificial layer on the inner surface. In an alternative embodiment, the sacrificial layer is prepared on the outer surface of the base scaffold. Similarly, paving a film on the inner surface of the foundation bracket, uniformly paving the outer surface of the foundation bracket with the water solution of the sacrificial layer, volatilizing the solvent of the water solution of the sacrificial layer, and removing the film to obtain the foundation bracket with the sacrificial layer on the outer surface.

In this embodiment, the "basic stent" refers to a stent covered before no stent covering, and may be a bare stent formed by laser cutting and braiding, or a stent obtained by reprocessing a bare stent formed by laser cutting and braiding. The material of the base stent is not particularly limited, and may be a biocompatible metal, such as nickel-titanium alloy, or stainless steel, or a biocompatible polymer material, such as polylactic acid. The release mode of the base stent is not particularly limited in this embodiment, and may be a self-expanding mode or a balloon-expanding mode.

Step 02, simultaneously carrying out electrostatic spinning on the inner surface and the outer surface of the basic bracket prepared in the step 01 to form an inner PTFE electrostatic spinning silk screen and an outer PTFE electrostatic spinning silk screen:

and simultaneously spraying PTFE electrostatic spinning aqueous solution on the inner surface and the outer surface of the basic bracket in an electrostatic spinning mode to form an inner PTFE electrostatic spinning silk screen and an outer PTFE electrostatic spinning silk screen respectively. Preferably, the PTFE electrostatic spinning aqueous solution comprises PTFE nano-particles, and the particle size of the PTFE nano-particles is 10nm-100nm. Further, the concentration of PTFE nanoparticles in the PTFE electrospun aqueous solution is 10wt% to 40wt%. BetterOptionally, the PTFE electrostatic spinning aqueous solution further comprises a blending agent to increase the solution viscosity of the PTFE electrostatic spinning aqueous solution, so that the PTFE electrostatic spinning aqueous solution is easier to spin. The concentration of the blending agent is 0.5wt% to 10wt%. Further, the blending agent is polyethylene oxide PEO, polyvinyl alcohol PVA, and the weight average molecular weight is 10 ⁵ ～10 ⁷ g/mol。

Preparing PTFE electrostatic spinning aqueous solution: selecting 40-60 wt% PTFE nanometer particle suspension water solution, adding blending agent (such as PEO or PVA with weight average molecular weight of 10) ⁵ ～10 ⁷ g/mol) and water, and uniformly stirring to obtain PTFE electrostatic spinning aqueous solution, wherein the concentration of PTFE nano particles is 10-40 wt%, the concentration of blending agent is 0.5-10 wt%, and the balance is water.

Step 03, sintering the basic bracket obtained in the step 02 to remove the sacrificial layer, placing the electrostatic spinning silk screen of the inner side PTFE and the electrostatic spinning silk screen of the outer side PTFE on the coating film on the inner surface and the outer surface of the basic bracket, and finally obtaining the coated bracket:

specifically, after spinning is completed, the basic bracket is sintered at a high temperature of 300-400 ℃, the sacrificial layer and the blending agent are decomposed and removed in the high temperature process, and simultaneously PTFE nano particles in the inner and outer PTFE electrostatic spinning silk screens can be fused and sintered together to form a PTFE electrostatic spinning film, so that the double-layer film-coated bracket with uniform inner and outer surfaces and firm combination is obtained.

The PTFE electrostatic spinning film prepared by the method has a thickness of 5-50 mu m and a porosity of more than 85%.

The porosity testing method comprises the following steps:

taking PTFE electrostatic spinning film with the size of 1cm x 1cm, measuring the thickness and the mass of the PTFE electrostatic spinning film, and calculating the apparent density rho of a film sample through a formula _{Appearance of the product} =m/(w×l×t), where ρ _{Appearance of the product} Represents the density of the coating film in g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the M represents the mass of the coating film, and the unit is g; w represents the width of the coating film, and the unit is cm; l represents the length of the coating film in cm; t represents the thickness of the coating film in cm.

Density ρ of PTFE raw material _{Raw materials} Is 2.2g/cm ³ Film porosity ε= (ρ) _{Appearance of the product} -ρ _{Raw materials} )/ρ _{Appearance of the product} *100％。

The porosity and thickness of the PTFE electrospun film in this example are shown in table 1.

TABLE 1 PTFE electrospun film porosity and thickness

Thickness μm	Porosity of the porous material
		5-20	>90％
20-50	85％-90％

The application also provides a device for preparing the PTFE tectorial membrane bracket, which is used for arranging the PTFE electrostatic spinning aqueous solution on the inner surface and the outer surface of the basic bracket so as to respectively form an outer PTFE electrostatic spinning silk screen and an inner PTFE electrostatic spinning silk screen. Fig. 2 is a schematic view of a device for preparing a PTFE covered stent according to an embodiment of the present application. In this embodiment, as shown in fig. 2, the electrospinning device includes a first spray head 1 and a second spray head 5. The first spray head 1 is used for spraying PTFE electrostatic spinning aqueous solution on the outer surface of the basic bracket under the action of a high-voltage electric field, and the second spray head 2 is used for spraying PTFE electrostatic spinning aqueous solution on the inner surface of the basic bracket under the action of the high-voltage electric field. Specifically, the first nozzle 1 is arranged perpendicular to the axis of the base bracket and is connected with a push injection device; the second spray head 5 extends away from the base bracket wall perpendicularly to the axis of the base bracket, then extends along the axial direction of the base bracket, and finally extends towards the base bracket wall perpendicularly to the axis of the base bracket. In this way, under the action of the injection device, the PTFE electrospun aqueous solution is sprayed on the inner surface of the base support through the second nozzle 5.

The electrostatic spinning device further comprises a clamping assembly 8, wherein the clamping assembly 8 is used for clamping one end of the basic support and driving the basic support to horizontally rotate, so that PTFE electrostatic spinning aqueous solution is circumferentially and uniformly sprayed on the inner surface and the outer surface of the basic support. Further, the electrospinning device further comprises a first support 2 and a second support 7 arranged horizontally. The first support member 2 is used for supporting the first spray head 1, and the second support member 7 is used for supporting the second spray head 5. Further, the relative distance between the base bracket and the first nozzle 1 and the second nozzle 5 can be changed. In the present embodiment, the first head 1 and the second head 5 are provided to be movable horizontally and vertically. Specifically, the first spray head 1 is movably disposed on the first support 2, and the second spray head 5 is movably disposed on the second support 7. In another embodiment, the first nozzle 1 and the second nozzle 5 are fixed to the first support 2 and the second support 7, respectively, and the base bracket can be horizontally moved by the clamping assembly.

Further, the electrostatic spinning device further comprises a high-voltage power supply, the positive electrode of the high-voltage power supply is electrically connected with the first spray head 1 and the second spray head 5, and the negative electrode of the high-voltage power supply is electrically connected with the base support 4. In this way, the first spray head 1 and the second spray head 5 respectively form a high-voltage electric field with the base support 4, and the PTFE electrostatic spinning aqueous solution overcomes surface tension to form a jet trickle under the action of the high-voltage electric field and falls on the surface of the base support. Further, in order to prevent the two electric fields from interfering with each other, the outside of the two spray heads and the support member is provided with an insulating coating, and the insulating barriers 3 and 9 are installed between the two spray heads and the base frame.

Further, as the diameter of the basic bracket is smaller, if the spinning distance in the basic bracket is not long enough, the heating component 6 in the spinning equipment can be started, the temperature of the spinning environment is improved, the volatilization speed of the water solvent in the PTFE electrostatic spinning aqueous solution is accelerated, and the PTFE electrostatic spinning aqueous solution is prevented from pasting in the spinning and net forming process.

Alternatively, in the first example, 99g purified water was first added to 1g polyethylene oxide (PEO, weight average molecular weight 5 x 10 ⁶ g/mol) powder, stirring for 12h gave a 1wt% aqueous PEO solution. And (3) taking a silicon rubber film, tightly attaching to the outer surface of the basic bracket, and winding the silicon rubber film, wherein the width of the film is equal to the length of the basic bracket. The base scaffold was placed horizontally, 5mL of PEO aqueous solution was added inside the base scaffold, the base scaffold was rotated to fill the solution into the base scaffold, and then the base scaffold was rapidly rotated until the solvent was completely volatilized. And removing the silicon rubber film outside the basic bracket to obtain the ultrathin sacrificial layer. Then 12g of water was added to 0.5g of peo powder (weight average molecular weight 5 x 10 ⁶ g/mol), stirring for 12h, adding 20g of PTFE aqueous solution with 60wt% and stirring for 2h to obtain PTFE electrostatic spinning aqueous solution with 38.5wt% of solute concentration. The foundation bracket is fixed in a special electrostatic spinning device, and an electrostatic spinning nozzle is arranged at the position 20cm above the foundation bracket and at the central position inside the foundation bracket. The speed of the left and right movement of the two spray heads is 20mm/min, and the rotation speed of the basic bracket is 120rpm. The spinning voltage was 12kV and the solution extrusion speed was 1mL/h. After spinning for 6 hours, the basic stent is put into a muffle furnace and sintered for 10 minutes at 400 ℃ to obtain the double-layer coated basic stent with the inner and outer coating thickness of 30 mu m and the porosity of 90 percent, and the specific shape of the PTFE coating is shown in figure 3.

A comparative example of the present application was described below, and an aqueous PEO solution and an aqueous PTFE electrospinning solution were prepared in the same manner as in example 1 described above. Then fixing the basic bracket in an electrostatic spinning device, stretching an electrostatic spinning nozzle into the central position inside the basic bracket, and carrying out electrostatic spinning, wherein the spinning parameters are as follows: the speed of the left and right movement of the spray head is 20mm/min, and the rotating speed of the basic bracket is 120rpm. The spinning voltage was 12kV and the solution extrusion speed was 1mL/h. After spinning for 6 hours, the basic bracket is put into a muffle furnace to be sintered for 10 minutes at 400 ℃ to obtain the film thickness of 30 mu m and the porosity of 90 percent in the basic bracket. Then the basic bracket is put into the electrostatic spinning device again, and an electrostatic spinning nozzle is positioned at a position 20cm above the basic bracket. The spinning parameters are as follows: the speed of the left and right movement of the spray head is 20mm/min, and the rotating speed of the basic bracket is 120rpm. The spinning voltage was 12kV and the solution extrusion speed was 1mL/h. After spinning for 6 hours, the basic bracket is put into a muffle furnace to be sintered for 10 minutes at 400 ℃ to obtain the outer layer coating thickness of the basic bracket with 30 mu m and the porosity of 90 percent. Because the PTFE membrane in the basic bracket is subjected to high temperature of 400 ℃ twice, nanofibers in the membrane collapse to block part of holes, so that the porosity of the inner-layer coating is reduced to below 85%.

It should be noted that in the present patent application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. In the present patent application, if it is mentioned that an action is performed according to an element, it means that the action is performed at least according to the element, and two cases are included: the act is performed solely on the basis of the element and is performed on the basis of the element and other elements. Multiple, etc. expressions include 2, 2 times, 2, and 2 or more, 2 or more times, 2 or more.

This specification includes combinations of the various embodiments described herein. Separate references to "one embodiment" or a particular embodiment, etc., do not necessarily refer to the same embodiment; however, unless indicated as mutually exclusive or as would be apparent to one of skill in the art, the embodiments are not mutually exclusive. It should be noted that the term "or" is used in this specification in a non-exclusive sense unless the context clearly indicates otherwise or requires otherwise.

All references mentioned in this disclosure are to be considered as being included in the disclosure of the application in its entirety so that modifications may be made as necessary. Further, it is understood that various changes or modifications of the present application may be made by those skilled in the art after reading the above disclosure, and such equivalents are intended to fall within the scope of the application as claimed.

Claims

1. A method for preparing a PTFE stent, the method comprising the steps of:

(01) Preparing a sacrificial layer on the surface of a basic bracket;

2. The method of producing a PTFE coated stent of claim 1, wherein the thickness of the sacrificial layer is 0.01mm to 0.05mm.

3. The method of claim 1, wherein the sacrificial layer is prepared from an aqueous solution of a water-soluble polymer material.

4. The method of producing a PTFE membrane-coated stent according to claim 3, wherein a film is laid on the other side of the base stent opposite to the side on which the sacrificial layer is to be provided for preventing an aqueous solution of a water-soluble polymer material from entering the surface on the other side of the base stent, before the sacrificial layer is produced in step (01).

5. A method of preparing a PTFE covered stent of claim 3, whereinThe water-soluble polymer material is polyethylene oxide PEO and polyvinyl alcohol PVA, and the weight average molecular weight is 10 ⁵ ～10 ⁷ g/mol。

6. The method for producing a PTFE coated stent according to claim 3, wherein the concentration of the aqueous solution of the water-soluble polymer material is 0.1wt% to 2wt%.

7. The method of producing a PTFE coated stent according to claim 1, wherein in step (02), the electrospinning is performed using an aqueous PTFE electrospinning solution comprising PTFE nanoparticles having a particle diameter of 10nm to 100nm.

8. The method of producing a PTFE coated stent of claim 7, wherein the concentration of PTFE nanoparticles in the PTFE electrospun aqueous solution is 10wt% to 40wt%.

9. The method of making a PTFE coated stent of claim 7, wherein the PTFE electrospun aqueous solution further comprises a blend, the blend having a concentration of 0.5wt% to 10wt%.

10. The method for preparing a PTFE coated stent according to claim 9, wherein the blending agent is polyethylene oxide or polyvinyl alcohol, and the weight average molecular weight is 10 ⁵ ～10 ⁷ g/mol。

11. The method of producing a PTFE covered stent of claim 1, wherein in step (02), the inner and outer surfaces of the base stent are simultaneously electrospun by a production apparatus comprising:

the positive electrode of the high-voltage power supply is used for being electrically connected with the first spray head (1) and the second spray head (5), the negative electrode of the high-voltage power supply is used for being electrically connected with the basic bracket (4),

the first spray head (1) is used for spraying PTFE electrostatic spinning aqueous solution on the outer surface of the basic bracket under the action of a high-voltage electric field;

and the second spray head (5) is used for spraying PTFE electrostatic spinning aqueous solution on the inner surface of the basic bracket under the action of a high-voltage electric field.

12. The method for producing a PTFE coated stent according to claim 1, wherein in the step (03), the sintering temperature is 300 to 400 ℃.

13. An apparatus for preparing a PTFE covered stent, the apparatus comprising: the spray head comprises a first spray head (1), a second spray head (5) and a high-voltage power supply;

14. The apparatus of claim 13, wherein the device comprises a plurality of sensors,

the first spray head (1) is arranged perpendicular to the axis of the base bracket;

the second spray head (5) is perpendicular to the axis of the foundation support and extends away from the inner wall of the foundation support, then extends along the axial direction of the foundation support, and finally extends towards the inner wall of the foundation support perpendicular to the axis of the foundation support.

15. The apparatus of claim 13, further comprising a clamping assembly (8), wherein the clamping assembly (8) is configured to clamp one end of the base support and drive the base support to rotate, and is configured to uniformly spray the PTFE electrospun aqueous solution circumferentially on the inner and outer surfaces of the base support.

16. The device according to claim 13, further comprising a first support (2), a second support (7);

the first supporting piece (2) and the second supporting piece (7) are horizontally arranged, the first spray head (1) is movably arranged on the first supporting piece (2), and the second spray head (5) is movably arranged on the second supporting piece (7).