CN113151980A

CN113151980A - PTFE (polytetrafluoroethylene) tubular covered stent and preparation method thereof

Info

Publication number: CN113151980A
Application number: CN202110297832.4A
Authority: CN
Inventors: 赵荟菁; 骆宇; 孟凯; 张克勤; 龚霄雁; 薛志恒; 刘浩
Original assignee: Suzhou Innomed Medical Device Co ltd; Suzhou University
Current assignee: Suzhou Innomed Medical Device Co ltd; Suzhou University
Priority date: 2021-03-19
Filing date: 2021-03-19
Publication date: 2021-07-23
Also published as: LU503086B1; WO2022193576A1

Abstract

The invention discloses a preparation method of a Polytetrafluoroethylene (PTFE) tubular covered stent, which comprises the following steps: s1, preparing a PTFE/PEO (polyethylene oxide) tubular fiber membrane by using a metal mandrel outer sleeve braided tube as a receiving device through an electrostatic spinning method; s2, drying the PTFE/PEO tubular fiber membrane, and sintering at 360-400 ℃ for 5-15 min; s3, providing a metal support, coating a polyurethane (TPU) adhesive on the surface of the metal support, then sleeving a tubular PTFE fiber membrane on the metal support, putting the metal support into water to remove N, N-Dimethylformamide (DMF) and solidify TPU; and taking out the metal stent, drying, sleeving a heat-shrinkable tube on the outer sleeve of the tubular PTFE fiber membrane, and heating to ensure that the tubular PTFE fiber membrane is shrunk to be more tightly combined with the metal stent, thereby obtaining the PTFE tubular tectorial membrane stent. The PTFE tubular tectorial membrane stent has good mechanical property, water permeability and blood compatibility, the hemolysis rate is lower than 5 percent, and the PTFE tubular tectorial membrane stent can support the cell adhesion and proliferation of Human Umbilical Vein Endothelial Cells (HUVECs) and has no cytotoxicity.

Description

PTFE (polytetrafluoroethylene) tubular covered stent and preparation method thereof

Technical Field

The invention relates to the technical field of blood vessel covered stents, in particular to a PTFE tubular covered stent and a preparation method thereof.

Background

Dilated arterial diseases such as pseudoaneurysm caused by trauma, infection, operation, immunological diseases, hypertension, atherosclerosis and the like seriously threaten the health of human beings. If the treatment is not performed in time, the gradually thinned blood vessel wall or the tumor wall lacking the muscular layer and the elastic layer is easy to rupture, and the death rate is up to 78-95%. The traditional therapy of the diseases is open surgery, and has the disadvantages of high risk, large wound, complex operation and the like. With the progress of material science, engineering technology and surgical technology, a novel tectorial stent intracavity isolation technology is invented. The technology is that the covered stent is used for completely isolating a parent artery from a false aneurysm cavity, and blood flow flows through the covered stent and cannot enter the aneurysm cavity. The covered stent endoluminal exclusion therapy has the advantages of small wound, quick recovery, few complications and the like, and is widely applied to the treatment of diseases such as aneurysm and the like at present. The covered stent for the endoluminal isolation operation is a combination of a metal stent and a covering membrane, not only retains the function of the metal stent, but also has the characteristics of a covering membrane material, at present, the covering membrane part is mostly made of terylene woven fabrics, ePTFE, polyurethane and the like, and the covering membrane prepared by the materials has defects in the aspects of blood compatibility, structural stability and the like, and easily causes the problems of thrombus, intimal hyperplasia and the like.

The electrostatic spinning technology is a simple and universal process, can prepare fibers with the diameter ranging from a few nanometers to a few micrometers, has high specific surface area and porosity, is easy to imitate the composition and structure of extracellular matrix, and is beneficial to cell growth and proliferation. However, the preparation of vascular stent-grafts using electrospinning techniques has been poorly studied.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a PTFE tubular covered stent prepared by an electrostatic spinning method, the covered stent has good mechanical property and water permeability, the hemolysis rate is lower than 5%, the blood compatibility is good, HUVECs cell adhesion and proliferation can be supported, cytotoxicity is avoided, and reference is provided for the subsequent application in the lumen isolation.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides a preparation method of a PTFE tubular tectorial membrane stent, which comprises the following steps:

s1, preparing a PTFE/PEO tubular fiber membrane by using a metal mandrel outer sleeve braided tube as a receiving device through an electrostatic spinning method;

s2, drying the PTFE/PEO tubular fiber membrane, and sintering at 360-400 ℃;

s3, providing a metal support, brushing a TPU adhesive on the surface of the metal support, then sleeving the sintered tubular PTFE fiber membrane on the metal support, and putting the metal support into water to remove DMF in the adhesive and solidify TPU; then taking out the metal stent, drying, sleeving a heat-shrinkable tube on the outer sleeve of the tubular PTFE fiber membrane, and heating the shrinkable tube to shrink the tubular PTFE fiber membrane so as to be more tightly combined with the metal stent, thereby obtaining the PTFE tubular covered stent;

or taking the metal bracket as a receiving device, and receiving the tubular TPU electrospun membrane on the metal bracket by an electrostatic spinning method; and then sleeving the sintered tubular PTFE fiber membrane outside the TPU electrospun membrane, sleeving a heat-shrinkable tube outside the tubular PTFE fiber membrane, heating the heat-shrinkable tube to melt the TPU electrospun membrane, and bonding the tubular PTFE fiber membrane and the metal stent to obtain the PTFE tubular covered stent.

In PTFE/PEO tubular fiber membranes, PEO acts only as a weak binder to connect PTFE particles and has no effect on the tensile force, so PEO needs to be removed. In the invention, the PTFE/PEO tubular fiber membrane is sintered, which aims to remove PEO in the fiber membrane, simultaneously, the PTFE particles are fused to fill the gaps of PEO, and finally, the complete and continuous PTFE fiber membrane with certain strength is obtained.

Further, in step S1, the spinning solution used is PTFE/PEO electrospinning solution, and the mass ratio of PTFE to PEO in the spinning solution is 99:1 to 97:3, preferably 97: 3.

Further, in step S1, the parameters of the electrostatic spinning are: the voltage is 12-20kV, the injection speed is 6-15 muL/min, the receiving distance is 15-22cm, the rotating speed of the receiving device is 200-600r/min, the relative humidity is (35 +/-5) - (45 +/-5)%, and the temperature is (18 +/-3) - (25 +/-3) ° C.

Further, in step S2, the sintering temperature is 360-400 ℃, preferably 380 ℃, and the sintering time is 5-15min, preferably 10 min.

Further, in step S3, the metal stent is a nitinol stent.

Further, in step S3, the TPU binder is obtained by dissolving TPU powder in DMF at a concentration of 18% to 25%, preferably 20% by weight.

Further, in step S3, the temperature for raising the temperature of the shrink tube is 140 ℃ to 160 ℃, preferably 150 ℃.

In a second aspect, the invention provides a PTFE tubular stent graft prepared by the method of the first aspect.

Further, the thickness of the PTFE tubular tectorial stent is 0.08-0.14mm, and preferably 0.1 mm.

In a third aspect, the invention provides the use of the PTFE tubular stent graft of the second aspect as a vascular stent.

Compared with the prior art, the invention has the beneficial effects that:

the PTFE tubular tectorial membrane stent has good mechanical property and water permeability, the hemolysis rate is lower than 5 percent, and the blood compatibility is better. In vitro cell experiments show that the PTFE tubular covered stent can support HUVECs cell adhesion and proliferation and has no cytotoxicity. The PTFE tubular tectorial membrane stent has potential application value in the field of tissue engineering.

Drawings

FIG. 1 is a flow chart for the preparation of a PTFE tubular stent graft;

FIG. 2 is a topographical view of a PTFE/PEO precursor membrane: (a) PTFF, PEO 99: 1; (b) PTFF, PEO 98: 2; (c) PTFF, PEO 97: 3;

FIG. 3 is a thermogram: (a) DSC curves of PTFE particles; (b) TG curves of PTFE particles, PEO powder, PTFE/PEO precursor film and film coated after sintering at 380 ℃;

FIG. 4 is an infrared spectrum of a PTFE/PEO precursor film before sintering and a PTFE film after sintering at 380 ℃;

FIG. 5 is a graph of (a) stress for PTFE membranes at different sintering temperatures and different sintering times; (b) strain;

FIG. 6 is a graph of the proliferation MTT of HUVECs cultured on each group of materials for 1,3,7 days;

FIG. 7 is a confocal image of HUVECs cultured on each group of materials for 1,3,7 days;

FIG. 8 is an SEM image of HUVECs cultured on each set of materials for 1,3, and 7 days.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The experimental methods used in the following examples are conventional methods unless otherwise specified, and materials, reagents and the like used therein are commercially available without otherwise specified.

In the following examples, the test materials used are as follows:

polytetrafluoroethylene dispersion (PTFE, solid content 60%, Suzhou Ke-Bio-medicine science and technology Co., Ltd.), polyethylene oxide (PEO, M)_w5,000,000Da, Scotch technologies, Inc., elastic polyurethane (TPU, Pasteur, Germany), N, N-dimethylformamide (DMF, Scotch Biomedicine technology, Inc.), glutaraldehyde (C)₅H₈O₂Shanghai pharmaceutical chemicals, Inc.), fetal bovine serum (FBS, Gibco, USA), phosphate buffer solution (PBS, Corning, USA), dimethyl sulfoxide (DMSO, Sigma, USA), trypsin (EDTA, Gibco, USA), fluorescein diacetate (FDA, Sigma, USA), diabase (streptomycin, Gibco, USA), Human Umbilical Vein Endothelial Cells (HUVECs), thiazole blue (MTT, Shanghai such as Gibber scientific and technological development, Inc.), DMEM medium (Corning, USA), 75% ethanol disinfectant (Anhuite food Co., Ltd.).

Example 1

Preparation of PTFE/PEO precursor films

An appropriate amount of PEO powder was weighed into deionized water using an Adventurer type electronic balance (Ohaaus instruments, Van.) and stirred with a 84-1 type magnetic stirrer (Shanghai Mey Yipu instruments manufacturing Co., Ltd.) until completely dissolved to obtain a 4 wt% PEO aqueous solution. And weighing the PTFE dispersion emulsion, mixing the PEO aqueous solution and the deionized water, and continuously stirring until the mixture is uniform to obtain the electrostatic spinning solution of PTFE/PEO in different proportions. Leading in the syringe of 5mL with the spinning solution, will wrap up the dabber (diameter is 4mm) that the stainless steel was woven the sleeve pipe and carry out electrostatic spinning as receiving arrangement (JDS02 type electrostatic spinning machine, Changsha appearance instrument science and technology limited), set up the electrostatic spinning parameter and be: the voltage is 15kV, the injection speed is 8 muL/min, the receiving distance is 20cm, the rotating speed of the receiving device is 400r/min, the relative humidity is (40 +/-5)%, and the temperature is (23 +/-3) ° C.

Preparation of PTFE coating film

After the electrostatic spinning is finished, the stainless steel braided sleeve sample covered with the PTFE/PEO fiber membrane is placed into a vacuum oven (DZF-6020B, Tianjin Industriety laboratory instruments Co., Ltd.) and is dried in vacuum for 10 hours at 60 ℃ to remove the water in the fiber membrane. After the drying is finished, the sample is immediately transferred to a box furnace (MF-1200C, Anhui Beideke apparatus and technology Co., Ltd.) and sintered at different sintering temperatures and different sintering times, so as to explore the influence of different sintering conditions on the preparation of the coating. And after sintering, taking down the coated membrane from the stainless steel braided sleeve to obtain the tubular PTFE coated membrane.

3. Preparation of covered stents

The preparation method of the film-coated bracket by adopting a TPU solution brushing method comprises the following specific operations:

firstly, weighing a proper amount of TPU powder by an electronic balance, adding the TPU powder into DMF, and stirring until the TPU powder is completely dissolved to obtain a 20 wt% TPU solution, namely the TPU adhesive. Then, as shown in FIG. 1, the TPU adhesive was brush-coated on the metal support, the tubular PTFE film was then coated on the TPU adhesive, the adhesive was put into deionized water to remove DMF from the adhesive and cure the TPU, and the resulting product was dried in WGLL-125BE type electrothermal constant temperature forced air drying oven (Tester instruments, Tech, Tianjin) for 10 min. And after taking out the stent graft from the oven, sleeving the PTFE film on a mandrel, sleeving a heat-shrinkable tube on the PTFE film, adjusting a hot air gun (DH-HG2-2000, Deleisi electric Co., Ltd.) to 150 ℃ to heat the shrinkable tube, so that the PTFE film and the metal stent are shrunk more tightly, and thus the PTFE film-coated stent is obtained.

Example 2

Example 2 differs from example 1 in that: the preparation method of the film-coated bracket by adopting the TPU electrospinning method comprises the following specific operations:

weighing a proper amount of TPU powder, dissolving in DMF, stirring until the powder is completely dissolved to obtain 30 wt% of TPU electrostatic spinning solution, and setting electrostatic spinning parameters as follows: the voltage is 16-17kV, a mandrel wrapped with a metal bracket is used as a receiving device, the receiving distance is 15cm, the flow rate is 13.33 mu L/min, and tubular TPU electrospun membrane is obtained after electrospinning for a certain time; and then sleeving the sintered tubular PTFE coated membrane outside the TPU electrospun membrane, adding a heat-shrinkable tube on the outermost layer, increasing the temperature of a hot air gun, heating the heat-shrinkable tube to melt the TPU electrospun membrane, so that the PTFE membrane is bonded with the metal stent, and the heat-shrinkable tube enables the PTFE membrane and the metal stent to be combined more tightly under the action of high temperature to obtain the PTFE coated stent.

Testing and characterization

1. Topography analysis

FIG. 2 is a microscopic view of electrospun precursor membranes of varying PTFE to PEO ratios in the dope with PEO as the binding component to allow PTFE particles to bind together under electrostatic spraying to form continuous fibers. As can be seen from fig. 2, when the PEO content in the spinning dope is small, continuous fibers cannot be formed. Fiber breakage was significant when PTFF: PEO was 99:1 (FIG. 2 a); the fiber breaking point decreased when the PEO content was gradually increased, with a PTFF: PEO of 98:2 (FIG. 2 b); when the ratio of PTFF to PEO was increased to 97:3, a continuous, unbroken fiber was formed, keeping the total solid content of the dope constant (fig. 2 c).

2. Thermal analysis

The PTFE/PEO precursor film prepared by electrostatic spinning is fluffy and has poor mechanical property, contains PEO, and can be sintered and removed to obtain a PTFE coated film with certain mechanical strength. It is therefore necessary to find a suitable sintering temperature by performing DSC and TG tests on the sample.

As can be seen from the DSC curve of FIG. 3(a), the melting point of the PTFE particles is 335.5 ℃; it can be seen in the TG curve of FIG. 3(b) that the PTFE particles start to decompose at 480 ℃; the pure PEO powder starts to decompose at 210 ℃ and is completely decomposed at 400 ℃; the TG curve of the PTFE/PEO precursor film showed a two-step mass loss, corresponding to the decomposition of PEO and PTFE, respectively, where the thermal decomposition temperature of the PEO component was consistent with the thermal decomposition temperature of the pure PEO powder. Therefore, the sintering temperature can be selected to be 335.5-480 ℃, in the temperature range, PEO is thermally decomposed, and PTFE can be melted to fill the gap left after PEO is decomposed, so that the PTFE fiber is connected into a complete PTFE fiber.

3. Fourier transform Infrared Spectroscopy (FTIR) analysis

The substantial removal of water and PEO from the polytetrafluoroethylene film after sintering was demonstrated by fourier transform infrared spectroscopy and the results are shown in figure 4. As can be seen from the figure, the precursor film before sintering has distinct PEO characteristic peaks: at 962cm^-1And 1105cm^-1A spectral band appears, thisAsymmetric CO stretching vibration due to PEO, 1350cm^-1And 1467cm^-1The band appearing here corresponds to CH of PEO₂Vibration, 2880cm^-1The band appearing at (a) corresponds to the CH stretch of PEO. No PEO peak was observed in the sintered film, while both the precursor film and the sintered film were 1201cm^-1And 1145cm^-1The maximum peak was observed, which corresponds to CF in PTFE₂The asymmetric stretching and the symmetric stretching of (a), which indicates that PEO in the precursor film has been removed, at least not detectable by FTIR measurement.

4. Analysis of mechanical Properties

The covered membrane part of the covered membrane stent for the endoluminal isolation operation also has better mechanical property. In the PTFE/PEO precursor membrane, PEO only serves as a connecting component of PTFE particles and has no effect on bearing tension, so that PEO needs to be removed, the PTFE particles are melted and gaps existing in PEO are filled, and finally, the complete, continuous and strong PTFE fiber membrane is obtained. Therefore, after the sintering temperature range is determined according to DSC and TG tests, the influence of the sintering temperature and the sintering time on the mechanical property of the PTFE coating is further researched. Different sintering temperatures are set: 360 ℃, 380 ℃ and 400 ℃; and different sintering times: 5min, 10min and 15 min.

Fig. 5(a) is a stress histogram for materials made at different sintering times and different sintering temperatures, and fig. 5(b) is a strain histogram for materials made at different sintering times and different sintering temperatures. As can be seen from the figure, the stress strain of the PTFE film is smaller when the sintering temperature is 360 ℃ than when the sintering temperature is 380 ℃, the sintering time is shorter (5min) or longer (15min), and the stress strain of the film is smaller than that of the sintering time which is 10min, because the PTFE is incompletely molten due to the lower sintering temperature or the short sintering time, and cannot enter a nano cavity generated after the decomposition of PEO components, so that the fibers are incomplete, and the mechanical property of the fibers is poor; and the long sintering time can cause the fiber to shrink, thereby having poor mechanical properties. When the sintering temperature is 380 ℃, the stress and the strain of the PTFE film are better; when the sintering temperature is increased to 400 ℃, the stress and strain of the PTFE film are obviously reduced, because the mechanical property is reduced due to severe shrinkage fracture of the fiber caused by overhigh sintering temperature. Therefore, in summary, the sintering temperature is 380 ℃, and the sintering time is 10min, so that the composite material has the optimal tensile mechanical property.

5. Water permeability analysis

The water permeability is an important characterization index of the covered stent for the endoluminal isolation, reflects the impermeability of the vessel wall to blood after the stent is implanted into a body, and needs to prepare the covered stent with good permeability. Since the water permeability of the coating film is closely related to the thickness thereof, the larger the thickness is, the higher the degree of pore coverage is, and the less the water permeation amount is. PTFE tubular tectorial membrane stents with different thicknesses are prepared, and the water osmotic pressure and the whole water flux are respectively tested by a self-built water permeability device, and the results are shown in Table 1.

As can be seen from Table 1, when the thickness is about 0.1mm, the water osmotic pressure is about 0.012MPa, slightly less than but close to 0.016 MPa; and the total water flux per unit time in 1, 2, 3, 4, 5, 7 and 10min flowing through the effective length of the blood vessel wall is 0.02-0.03mL cm under 0.016MPa^-2·min^-1In between, all are far less than the standard specified 100mL cm^-2·min^-1Therefore, the covered stent can not leak a large amount of blood under normal blood pressure after being actually implanted into a human body, and simultaneously can have a small amount of blood infiltration to ensure the growth of an inner membrane and the supply of nutrition of an outer membrane; when the thickness is increased to about 0.14mm, the water osmotic pressure is increased to 0.023MPa which is higher than the blood pressure of a human body, so that the osmosis can not occur, and the whole water flux at each time point under 0.016MPa is 0, which is not beneficial to the growth of the intima. Therefore, when the thickness is about 0.1mm, the water permeability is satisfactory.

TABLE 1 osmotic pressure and Total Water Permeability of PTFE tubular Stent covered with a Membrane of different thickness

7. Experimental analysis of hemolysis

The hemolysis of the material is judged by measuring the degree of damage to red blood cells during the extracorporeal contact of the material with blood. If the material is poor in hemocompatibility, it is highly likely that erythrocytes are ruptured, and hemolysis occurs. The hemolysis experiment is an important index for evaluating the blood compatibility of the biological material. According to the standard ISO 10993-4, the hemolysis rate of the material is less than 5%, and the material is considered to meet the requirements of biomedical materials.

As shown in Table 2, the hemolysis rate of the PTFE tubular stent graft is 2.84%, which is less than 5%, indicating that the material is safe and does not cause hemolysis.

TABLE 2 hemolysis test results for PTFE-coated and tubular-shaped stent grafts

Material	Absorbance of the solution	Rate of hemolysis
			PTFE tubular tectorial membrane stent	0.048±0.002	2.84％
Negative control	0.026±0.003	0.00％
			Positive control	0.776±0.007	100％

6. Cytotoxicity assays

The biomaterial should have good cell compatibility, i.e., adaptability between the material and the attachment and growth of cells. The good cell compatibility of the material can promote the adhesion endothelialization of vascular endothelial cells on the surface of the material, and a vascular endothelial layer structure is formed in a short time. HUVECs cells are planted on the surface of the material, and the growth condition of endothelial cells of the material is observed.

FIG. 6 is a graph of MTT proliferation of cells on different materials, and it can be seen that the number of cells on the tubular stent graft and the blank control sample all showed a tendency to increase with the increase of the culture time, and the growth rate of the cells on the tubular stent graft was faster; on day 7, the number of cells on the stent graft was greater than that of the blank control, demonstrating good cell compatibility.

The cell growth on the material was qualitatively characterized by laser confocal and scanning electron microscopy, as shown in fig. 7. It can be seen that on day 1 of cell seeding, the cells were more evenly distributed on the slide (FIG. 7d), while on the tubular stent graft (FIG. 7a), the cells adhered more to the portion near the metal stent than to the stent graft, which also demonstrates that the TPU adhesive used in the present invention is cell compatible. By day 3, similar to the MTT test results, cell proliferation was more clearly seen, and more cells were also adhered to the tubular stent graft at the graft portion. By day 7 (fig. 7c, f), a large number of cells adhered to the surface of each material, exhibiting a sheet-like adhesion phenomenon, indicating the onset of endothelialization.

FIG. 8 is an SEM image of HUVECs cells grown on a tubular stent graft and a glass slide. As can be seen, on day 1 (FIGS. 7a and d), the number of cell adhesions on the surface of each material was small, and it can be seen from the SEM image at 2000 magnification that the cells were not spread. As the culture time increased, by day 3 (fig. 7b, e), the number of cells on the surface of each material increased and many cells began to form cell clumps, fused together, and gradually formed a monolayer of cells adhering to the fiber mesh and the slide. After 7 days of culture (fig. 7c, f), HUVECs cells had spread over the entire fiber mesh and cell slide, and very significantly a monolayer of cells was visible covering the surface of the material. These results demonstrate that the tubular stent-graft is not toxic to HUVECs cells and can support the adhesion and proliferation of endothelial cells.

In conclusion, the PTFE-PEO electrostatic spinning solution is prepared by stirring the PTFE dispersion emulsion and the PEO aqueous solution, and then the PTFE coating film obtained by electrostatic spinning, vacuum drying and sintering can ensure that PEO components in the PTFE coating film are basically removed and has good mechanical properties. And then the tubular PTFE coated membrane directly prepared is bonded and thermally shrunk and reinforced to obtain the tubular coated stent, and tests prove that the tubular coated stent has good water permeability, the hemolysis rate is lower than 5 percent, and the blood compatibility is good. In vitro cell experiments show that the PTFE tubular tectorial membrane stent supports HUVECs cell adhesion and proliferation, and has no cytotoxicity. The PTFE tubular tectorial membrane stent has potential application value in the field of vascular tectorial membrane stents.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.

Claims

1. A preparation method of a PTFE tubular tectorial membrane stent is characterized by comprising the following steps:

s2, drying the PTFE/PEO tubular fiber membrane, and sintering at 360-400 ℃ for 5-15 min;

2. The method for preparing the PTFE tubular stent graft of claim 1, wherein in step S1, the adopted spinning solution is an electrostatic spinning solution of PTFE/PEO, and the mass ratio of PTFE to PEO in the spinning solution is 99:1-97: 3.

3. The method for preparing a PTFE tubular stent-graft according to claim 1, wherein in step S1, the electrospinning parameters are: the voltage is 12-20kV, the injection speed is 6-15 muL/min, the receiving distance is 15-22cm, the rotating speed of the receiving device is 200-600r/min, the relative humidity is (35 +/-5) - (45 +/-5)%, and the temperature is (18 +/-3) - (25 +/-3) ° C.

4. The method for preparing a PTFE tubular stent-graft according to claim 1, wherein in step S2, the sintering temperature is 380 ℃ and the sintering time is 10 min.

5. The method for preparing a PTFE tubular stent-graft according to claim 1, wherein in step S3, the metal stent is a nitinol stent.

6. The method of claim 1, wherein in step S3, the TPU adhesive is prepared by dissolving TPU powder in DMF at a concentration of 18-25%.

7. The method for preparing a PTFE tubular stent graft according to claim 1, wherein the temperature of the contracted tube is raised to 140-160 ℃ in step S3.

8. A PTFE tubular stent graft prepared according to the method of any one of claims 1-7.

9. The PTFE tubular stent graft of claim 8, wherein the PTFE tubular stent graft has a thickness of 0.08-0.14 mm.

10. Use of a PTFE tubular stent graft according to claim 9 as a vascular stent.