CN113622053A

CN113622053A - Fiber and preparation method thereof, film, covered stent and preparation method thereof

Info

Publication number: CN113622053A
Application number: CN202010383654.2A
Authority: CN
Inventors: 徐海燕; 周奇; 李俊菲; 罗七一
Original assignee: Shanghai Microport Medical Group Co Ltd
Current assignee: Shanghai Microport Medical Group Co Ltd
Priority date: 2020-05-08
Filing date: 2020-05-08
Publication date: 2021-11-09

Abstract

The invention relates to a fiber and a preparation method thereof, a film, a covered stent and a preparation method thereof, the prepared fiber has developing property, and a developer is wrapped inside the fiber, so that the harm of the developer to a human body is reduced, the developing stability is good, and the long-term development can be realized.

Description

Fiber and preparation method thereof, film, covered stent and preparation method thereof

Technical Field

The invention relates to the technical field of medical instruments, in particular to a developable fiber, a tectorial membrane and a tectorial membrane stent.

Background

Coronary perforation is a very serious complication in Percutaneous Coronary Intervention (PCI) and can be life-threatening if not handled in time. Coronary perforation refers to the situation that in PCI surgery, blood vessels are torn, so that contrast medium or blood leaks out of the blood vessels from the torn part of the blood vessels, and the patients suffer from cardiac tamponade, coronary ventricular fistula, myocardial infarction, emergency CABG (coronary artery bypass graft) and the like in a short time, which can often endanger the lives of the patients. Recent summary analysis has shown that the mortality rate for severe coronary perforation can be as high as 20%, and even as high as 40% for coronary perforation in emergency surgery. In particular, with the increase in the number of PCI procedures in recent years, the development and application of new PCI techniques (chronic occlusive lesion interventional techniques, drug eluting stents, degradable stents, etc.), and the trend toward aging population, the incidence of coronary perforation tends to increase.

In comparison, the tectorial membrane stent has higher safety in the aspect of clinically treating perforation and is widely used. The covered stent is a stent covered with a special membranous material on the surface of a metal stent, not only retains the function of the metal stent, but also has the characteristics of the membranous material, and can treat complex lesions such as perforation, aneurysm and the like. At present, the coating in the covered stent is mainly prepared from high polymer materials such as polytetrafluoroethylene (PTFE for short) and polyurethane (PU for short), and most of the materials only contain elements with low specific gravity such as C, H, O, F (carbon, hydrogen, oxygen and fluorine) and cannot be detected by X-rays, so the high polymer covered materials generally have no developing property. Therefore, in the processes of conveying, expanding and later-stage use, whether the film is curled, displaced and other adverse events are difficult to detect, and great difficulty is brought to follow-up and observation in the later stage.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide a fiber, a method for preparing the same, a coating, a stent graft, and a method for preparing the same, wherein the prepared fiber is developable, and a developer is dispersed in the fiber and does not dissociate from the surface of the material, thereby reducing the toxicity of the developer to human body, and the developer has good stability and longer development performance.

To achieve the above object, according to a first aspect of the present invention, there is provided a method for producing a fiber for producing a multilayer fiber, comprising:

and (3) carrying out electrostatic spinning to obtain the fiber with the inner layer containing the developer, and the outer layer of the fiber containing no developer.

Optionally, the step of electrospinning to obtain fibers with inner layers containing the developer comprises:

obtaining a shell layer spinning raw material, wherein the shell layer spinning raw material comprises a high polymer material;

obtaining a nuclear layer spinning raw material, wherein the nuclear layer spinning raw material comprises a high polymer material and a developer;

adding a shell layer spinning raw material into an outer layer cavity of an injector, and adding a core layer spinning raw material into an inner layer cavity of the injector, wherein the outer layer cavity covers the inner layer cavity;

and respectively extruding a shell layer spinning raw material and a core layer spinning raw material at a certain speed, and carrying out electrostatic spinning to obtain the multilayer fiber.

adding a shell spinning raw material into an outer layer cavity of the injector;

extruding a shell layer spinning raw material at a certain speed, and simultaneously introducing gas carrying a developer into the inner layer cavity coated by the outer layer cavity at a certain speed to carry out electrostatic spinning to obtain the multilayer fiber.

Optionally, the inner diameter of the inner layer cavity is 1/10-1/2 of the inner diameter of the outer layer cavity.

Optionally, the inner diameter of the inner layer cavity is 1/4-1/2 of the inner diameter of the outer layer cavity.

Optionally, the gas is an inert gas.

Optionally, the inner diameter of the inner layer cavity is 1/10-1/3 of the inner diameter of the outer layer cavity.

Optionally, before the gas carrying the developer is introduced into the inner cavity, the method further includes: the developer is processed into powder, dried and milled.

Optionally, the electrospinning is solution electrospinning, and the process conditions include: the spinning voltage is 18 kv-23 kv; the receiving distance is 15 cm-25 cm; the extrusion speed of the core layer spinning raw material is 0.4 ml/h-1.5 ml/h; the extrusion speed of the shell layer spinning raw material is 0.7 ml/h-1.5 ml/h; the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45% +/-5%; or the electrostatic spinning is melt electrostatic spinning, and the execution process conditions comprise: the spinning voltage is 20 kv-30 kv; the receiving distance is 10 cm-20 cm; the extrusion speed of the core layer spinning raw material is 0.5 cm/min-1.5 cm/min; the extrusion speed of the shell layer spinning raw material is 1 cm/min-2 cm/min, the spinning environment temperature is not lower than the melting point temperature of the high polymer material, and the relative humidity is 20% +/-5%.

Optionally, the electrospinning is solution electrospinning, and the process conditions include: the spinning voltage is 15 kv-25 kv; the receiving distance is 15 cm-25 cm; the extrusion speed of the shell layer spinning raw material is 0.4 ml/h-1.5 ml/h; the flow rate of the developer introduced into the inner layer cavity is 1 mg/h-5 mg/h; the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45% +/-5%; or the electrostatic spinning is melt electrostatic spinning, and the execution process conditions comprise: the spinning voltage is 25 kv-35 kv, the receiving distance is 15 cm-25 cm, and the extrusion speed of the shell layer spinning raw material is 0.5 cm/min-1.5 cm/min; the flow of the developer introduced into the inner layer cavity is 1 mg/min-10 mg/min; the spinning environment temperature is not lower than the melting temperature of the high polymer material, and the relative humidity is 20 +/-5%.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a fiber prepared by the method for preparing a fiber according to any one of the above.

In order to achieve the above object, according to a third aspect of the present invention, there is provided a coating film made of a fiber or a fabric made of the fiber, and the fiber is prepared by the fiber preparation method according to any one of the above.

To achieve the above object, according to a fourth aspect of the present invention, there is provided a method of manufacturing a stent graft, comprising:

a developable coating is prepared by using the fiber or the fabric made of the fiber, and the developable coating is covered on the surface of the stent body.

Optionally, the step of covering the stent body with the developable coating comprises:

and depositing the fibers on the surface of the stent body for collection to obtain the stent with the surface covered with the developable tectorial membrane.

depositing fibers on the surface of a fiber receiving device for collection to obtain a tubular or sheet-shaped original coating;

covering the surface of the stent body with a tubular or sheet-shaped original covering film to obtain the stent with the surface covered with the developable covering film.

Optionally, before depositing the fiber on the stent body, the method further comprises: covering a portion of the stent body with a cover;

and after the fiber is collected, the method also comprises the following steps: cutting along the edge of the covering to obtain a spiral or ring-shaped developable coating.

Optionally, the stent body is a bare stent or a covered stent covered with an elastic covering film; when the stent body is a covered stent, the developable covering film is combined with the elastic covering film through physical acting force.

Alternatively, the developable film and the elastic film are bonded by a thermal compression process, or the developable film and the elastic film are bonded by an adhesive.

To achieve the above object, according to a fifth aspect of the present invention, there is provided a stent graft comprising a stent body and a developable coating covering a surface of the stent body; the developable coating is prepared from fibers, the fibers comprise an outer layer and at least one inner layer, the outer layer is composed of a high polymer material, and the inner layer contains a developer or contains a developer and a high polymer material.

Optionally, the stent body is a bare stent, or the stent body is a covered stent covered with an elastic covering membrane.

Optionally, when the stent body is a stent graft, the developable coating at least partially covers the elastic coating.

Optionally, the developable coating is spiral-shaped or ring-shaped.

The fiber and the preparation method thereof, the film, the covered stent and the preparation method thereof provided by the invention have at least one of the following advantages:

the prepared fiber contains the developer, so that the fiber can be used for preparing the developable coating, and the developable coating is applied to the covered stent, so that the state of the coating in the body can be monitored conveniently in the processes of conveying, expanding and later use of the covered stent, the accuracy of the operation is improved, the operation difficulty is reduced, and the treatment effect is improved.

The developer in the prepared fiber is dispersed in the fiber and does not dissociate on the surface of the fiber, on one hand, the mode is favorable for coating some developers with higher activity, such as nano-scale developers, in the fiber, so that the selectable range of the developer is large, the preparation is more flexible, on the other hand, the harm of the developer to a human body can be reduced, the safety of instruments is improved, on the other hand, the stability of the developer is high, the development is more durable and reliable, the developer can be uniformly dispersed in the fiber, the development effect is good, meanwhile, the performance of a high polymer material cannot be influenced, the original function of the covered stent cannot be influenced, and the normal use of the covered stent is ensured.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. In the drawings:

FIG. 1 is a general flow chart of a preferred embodiment of the present invention for preparing fibers;

FIGS. 2 and 3 are flow charts of fiber production in accordance with a preferred embodiment of the present invention;

FIG. 4a is a schematic overall view of a stent graft according to a preferred embodiment of the present invention, showing a bare stent inside in perspective;

FIG. 4b is a cross-sectional view of the stent graft of FIG. 4a taken along line A-A;

FIG. 5 is a schematic illustration of the preparation of a developable coating in a preferred embodiment of the present invention, showing the bare stent inside in perspective;

FIGS. 6 a-6 b are schematic axial cross-sectional views of the injector of FIG. 5;

FIGS. 7 a-7 b are schematic axial cross-sectional views of fibers prepared using the injector of FIGS. 6 a-6 b, respectively;

FIG. 8 is a schematic illustration of a preferred embodiment of the present invention in which the developable coating is helically distributed over the stent graft, with the bare stent inside shown in perspective;

FIG. 9 is a schematic illustration of a preferred embodiment of the present invention showing a developable coating in a ring-like distribution over the stent graft, with the bare stent inside shown in perspective.

The reference numerals are explained below:

a stent graft 10; a bare stent 101; an elastic coating film 102; a developable coating film 103;

a molding device 20; a spinning needle 201; a fiber 202; a mandrel 203; a syringe 204; double layer capillary 201b, arrow 301; an outer layer 202 a; an inner layer 202 b.

The same or similar reference numbers in the drawings identify the same or similar elements.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

Furthermore, each of the embodiments described below has one or more technical features, and thus, the use of the technical features of any one embodiment does not necessarily mean that all of the technical features of any one embodiment are implemented at the same time or that only some or all of the technical features of different embodiments are implemented separately. In other words, those skilled in the art can selectively implement some or all of the features of any embodiment or combinations of some or all of the features of multiple embodiments according to the disclosure of the present invention and according to design specifications or implementation requirements, thereby increasing the flexibility in implementing the invention.

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to the appended drawings. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. As used in this specification, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the meaning of "a plurality" generally includes two or more unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. The term "axial" generally refers to a direction parallel to the axis of the stent graft, and "radial" generally refers to a direction perpendicular to the axial direction and directed toward the axis. It is also to be understood that the present invention repeats reference numerals and/or letters in the various embodiments. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It will also be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present.

The inventors found that in the prior art, the methods for developing the polymer material are mainly divided into physical blending, chemical synthesis and surface coating. Although these methods can prepare a developable polymer coating material, they all have some problems, for example, the chemical synthesis method has a great difficulty in operation, the surface coating method does not have long-term developability, and the physical blending method can control the loading amount of the developer, so that it is most convenient. However, the developer existing in the conventional physical blending mode has the problems of uneven dispersion and influence on the physical properties of the material. Therefore, if these methods are used to prepare a developable coating, there are problems that the operation is difficult, long-term development cannot be performed, the development effect is not good, and the physical properties of the coating are affected.

Furthermore, the inventor finds that electrostatic spinning is a simple, convenient, cheap and environment-friendly spinning technology, the diameter of the prepared fiber is between micron and nanometer, the surface has higher porosity and good biocompatibility, the prepared fiber can play a role in uniform dispersion, the physical performance of a high polymer material cannot be influenced, and the flexibility of the high polymer film material can be well maintained. Therefore, by utilizing the electrostatic spinning technology, a developable coating can be prepared relatively simply and conveniently, and then the coating is applied to a covered stent, so that the coating of the covered stent also has developability, the covered stent has the functions of supporting blood vessels and isolating blood flow, and the coating can also be developed, the state of the coating is detected through development under X-rays conveniently in the processes of conveying, expanding and later use of the covered stent, and therefore, the accuracy of the operation is improved, the treatment effect is improved, and the difficulty of later follow-up visit and observation is reduced.

Therefore, the invention mainly takes the polymer material as the object, utilizes the electrostatic spinning technology to prepare the developable superfine fiber, and combines the fiber or the fabric made of the fiber with the surface of the stent, thus obtaining the covered stent with the developable covering film covered on the surface. It is understood that a fiber refers to a substance consisting of continuous or discontinuous filaments; by fabric is meant a flat film mass made up of fibers by crossing, intertwining, or connecting structures.

Specifically, as shown in fig. 1, the present invention provides a method for preparing a fiber, including step S1 and step S2. That is, step S1 is performed to perform electrospinning, and finally the fiber in step S2 is obtained in which the inner layer contains the developer and the outer layer does not contain the developer. Therefore, the prepared fiber has at least two layers, the outer layer of the fiber is composed of a high polymer material, the inner layer of the fiber can be composed of a pure developer, the inner layer of the fiber can also be composed of the high polymer material and the developer together, and the developer is dispersed in the high polymer material in the form of extremely tiny particles.

It should be known that the surface of the fiber prepared by the preparation method does not contain the developer, and the developer is wrapped in the fiber, so that the developer cannot be separated out, the toxicity to a human body is avoided, the use safety of instruments is ensured, and meanwhile, the developer is good in stability and can achieve the effect of long-term development. It should also be understood that the fibers are not limited to one inner layer, but may be provided with a plurality of inner layers inside the outer layer, and at least a part of the inner layers contain a developer. Herein, the outer layer is an outermost layer, and the inner layer is a portion surrounded by the outer layer.

In order to obtain a fiber with an inner layer containing developer and an outer layer containing no developer, in a preferred mode of manufacture, as shown in FIG. 2, the following steps are included:

step S11, including: step S111, obtaining a shell layer spinning raw material, wherein the shell layer spinning raw material comprises a high polymer material; step S112, obtaining a nuclear layer spinning raw material, wherein the nuclear layer spinning raw material comprises a high molecular material and a developer;

step S12, including: adding the shell layer spinning raw material into an outer layer cavity of the injector in the step S121; and in step S122, adding the core layer spinning raw material into an inner layer cavity of the injector, the outer layer cavity covering the inner layer cavity;

thereafter, step S13 includes: and extruding the shell layer spinning raw material and the core layer spinning raw material at certain speeds respectively, and performing electrostatic spinning to obtain the fiber in the step S2 finally.

In more detail, electrospinning includes two processes, solution electrospinning and melt electrospinning, respectively. If the solution electrostatic spinning is adopted, the shell layer spinning raw materials comprise a high polymer material and a solvent, the high polymer material is dissolved in the solvent to form a shell layer solution, meanwhile, the core layer spinning raw materials comprise the high polymer material, a developing agent and the solvent, and the high polymer material and the developing agent are dissolved in the solvent to form a mixed solution. In the case of melt electrospinning, the shell layer spinning raw material comprises a polymer material, the polymer material is heated to be in a molten state, the polymer material in the core layer spinning raw material is also heated to be in a molten state, and the developer can be heated (not molten) or selected from high-temperature-resistant developing materials, and is dispersed in the polymer material.

In the manufacturing method shown in fig. 2, the fiber has a double-layer structure, the inner layer is composed of a polymer material and a developer, the developer is dispersed in the polymer material of the inner layer, and the outer layer is composed of only the polymer material without any developer. The mode can coat the developer in the fiber, reduces the poison of the developer on human body, and has more durable developing performance.

In another preferred preparation, as shown in fig. 3, the method comprises the following steps:

step S11' includes: step S111', obtaining a shell layer spinning raw material, wherein the shell layer spinning raw material comprises a high polymer material; and providing a developer carrying gas, preferably an inert gas, at step S112';

step S12' includes: in the step 121', adding a shell layer spinning raw material into an outer layer cavity of a syringe; and in step S122', introducing gas carrying the developer into the inner cavity of the injector;

thereafter, step S13' includes: extruding a shell spinning raw material at a certain speed, introducing gas carrying a developer into the inner layer cavity at a certain speed, and carrying out electrostatic spinning to finally obtain the fiber in the step S2.

In the preparation shown in fig. 3, the fiber is also of a two-layer structure, the inner layer of the fiber is composed of only the developer, and the outer layer is composed of only the polymer material without any developer. The mode can coat some developers with higher activity, such as nano-scale developers, in the fibers, improve the stability of the developers and reduce the precipitation of the developers.

No matter which preparation method is adopted, the operation is simple and convenient, the developer can be uniformly dispersed in the fiber, the developing effect is good, the physical property of the high polymer material cannot be influenced, and the flexibility of the high polymer film material can be well maintained.

In addition, the invention also provides a coating prepared by adopting the fiber or the fabric, so that the coating has developability, the developing effect of the coating is good, and the development is stable and durable. In addition, the invention also provides a covered stent, which comprises a stent body and a developable covering film, wherein the developable covering film covers the surface of the stent body, and the developable covering film is also prepared by adopting the fiber or fabric made of the fiber, so that the covering film on the covered stent has developability.

Further, the preparation process of the covered stent specifically comprises the following steps:

and preparing a developable coating by using the prepared fiber or fabric, and covering the developable coating on the surface of the stent body to obtain the stent graft with the developable surface coating.

Further, the developable coating can be covered on the surface of the stent body in a mode of: the method comprises the steps of directly depositing fibers on the surface of a stent body for collection, or depositing the fibers on the surface of a fiber receiving device for collection to obtain a tubular or sheet-shaped original covering film, and then covering the tubular or sheet-shaped original covering film on the surface of the stent body.

In addition, the stent graft prepared may be a single-layer stent graft or a double-layer stent graft. When the covered stent is a single-layer covered stent, the fibers are directly deposited on the bare stent so as to directly cover the developable covered membrane on the surface of the bare stent, and the covered stent is obtained. When the covered stent is a double-layer covered stent, an elastic covered membrane already exists on the surface of the original bare stent, so that fibers are directly deposited on the surface of the elastic covered membrane, and the covered stent with the double-layer covered membrane is finally obtained.

The bare stent is of conventional construction and the present invention will not be described in detail. For example, the bare stent is a hollow reticular structure, which can be a braided stent or a laser cutting stent, and has the function of supporting blood vessels through the expansion of the bare stent. The bare stent can be formed by laser cutting of a metal pipe or a non-metal pipe. Alternatively, the bare stent may be woven from metal or non-metal woven wires. The material of the bare stent can be a known degradable material or a non-degradable material. The method is not limited to laser cutting, weaving, or the like, and may be 3D printing, or die casting.

The elastic coating covers the outer surface of the bare stent, which is also of conventional construction, and is not described in detail herein. It should be understood that the material of the elastic coating is mainly an elastic polymer material, and the elastic polymer material can be one of polyurethane, poly (1, 3-propylene terephthalate), polyolefin elastomer, polysaccharide, natural rubber, collagen, polycaprolactone, polylactic acid, polyglycolic acid, polyethylene glycol, polyglycolide, polydioxanone, or the like, or a copolymer or a blend of these materials. It is also known that the elastic coating film cannot be detected by X-rays and therefore, does not have developability. In the present invention, the elastic coating can be prepared by conventional techniques, such as injection molding extrusion, spraying, etc., and the specific manner is not limited. Generally, the surface of the elastic coating has pores, which can promote the migration of cells on the surface and at the same time, can isolate the blood flow. The elastic covering film has elasticity and can expand along with the expansion of the bare stent. The position of the elastic covering film is set according to the position of actual use, and the length of the elastic covering film does not exceed the length of the bare stent. The elastic covering film can be provided with a space or a window in the middle of the covering film according to requirements so as to prevent the branch blood vessel from being blocked. Here, the elastic coating is provided with a space in the middle of the coating, which means that the elastic coating is divided into two parts that are provided with a space such that the bare stent between the two parts is not covered by the elastic coating. The window is a hole that allows blood flow through the window into the branch vessel.

In the preferred embodiment of the invention, the developable coating is mainly covered on the outer surface of the elastic coating, so that the flexibility of the whole coated stent is ensured through the good elasticity of the elastic coating, and the developable coating is favorable for ensuring the capability of the coated stent passing through complex lesions and can better isolate blood flow. The elastic polymer material in the developable coating can also be selected from one of polyurethane, poly (1, 3-propylene terephthalate), polyolefin elastomer, polysaccharide, natural rubber, collagen, polycaprolactone, polylactic acid, polyglycolic acid, polyethylene glycol, polyglycolide, polydioxanone and the like, or a copolymer or a blend of the materials. Therefore, the developable coating also has elasticity and can expand along with the expansion of the bare stent, the flexibility of the covered stent is not influenced by the arrangement of the developable coating, and the effectiveness of the covered stent in isolating blood flow can be ensured.

The developable tectorial membrane is preferably combined with the elastic tectorial membrane through physical acting force, so that the influence on the physical property of the tectorial membrane can be avoided, and the effectiveness of the tectorial membrane stent is ensured. The physical force is, for example, van der waals force, so that the elastic coating film and the developable coating film are firmly bonded together by the van der waals force. More preferably, the means of achieving van der waals forces may be thermal or adhesive bonding. The elastic coating film may be completely covered with the developable coating film, or a part of the elastic coating film may be covered with the developable coating film and the other part may be exposed to the outside. The mode that can develop tectorial membrane cover part elasticity tectorial membrane can be the spiral and distribute, or link form distributes, can clearly discern the boundary of can developing the tectorial membrane under the X-ray, and the design like this can improve the bending property of covered stent, promotes covered stent's ability through complicated pathological change.

The developer may be selected from a heavy metal-containing developer, an ionic developer or a non-ionic developer. The heavy metal-containing developer may be barium sulfate or nano-metal particles, such as nano-gold. The ionic developer may be one or more combinations of iodipamide, diatrizoic acid, iothalamate, and iophthalate. The non-ionic developer may be one or more of iohexol, iomeprol, iosetidol, ioversol, iopromide, iopamidol, ioversol, iotrolan and iodixanol. It is understood that these conventional developers can be dispersed in the polymer material in a blending manner, or developing groups can be grafted on the polymer material by chemical means, so as to obtain the polymer fiber containing the developers, and these blending manner or chemical means do not have any influence on the physical properties of the elastic polymer material, so that the use effect of the coating film can be ensured.

The stent graft and the method for making the same according to the present invention will be further described with reference to the drawings and the preferred embodiments, so as to further highlight the features and characteristics of the above embodiments.

FIGS. 4a and 4b are a schematic overall appearance and a transverse cross-sectional view, respectively, of a stent graft 10 in accordance with a preferred embodiment of the present invention. As shown in FIGS. 4a and 4b, the embodiment of the invention relates to a covered stent 10, which specifically comprises a bare stent 101, an elastic covering film 102 and a developable covering film 103 which are arranged in sequence from inside to outside. That is, the elastic coating 102 covers the outer surface of the bare stent 101, and the developable coating 103 covers the outer surface of the elastic coating 102.

As previously described, the developable coating 103 may be prepared by a solution electrospinning process or a melt electrospinning process. In the following description, the process of preparing the stent graft will be described by using the solution electrospinning process and the melt electrospinning process to prepare the developable coating 103 as an illustration.

Fig. 5 is a schematic structural view of a molding apparatus in a preferred embodiment of the present invention. As shown in fig. 5, the embodiment of the present invention also relates to a molding apparatus 20 for producing the developable coating film 103. The molding apparatus 20 includes a fiber generating device including a fiber generator (not shown), a fiber collecting device, and a high voltage generator (not shown). The fiber collection device includes a rotatable mandrel 203. The fiber generator includes an injector 204, the injector 204 having a spinning needle 201. A cavity is formed inside the spinning needle 201 and is used for filling spinning raw materials. The mandrel 203 is arranged at a position below the spinning needle 201. The high voltage generator has a high voltage terminal and a ground terminal, the high voltage terminal is disposed inside the spinning needle 201, and the ground terminal is connected to the mandrel 203.

In one embodiment, the bare stent 101 is placed directly over the mandrel 203 and rotated with the mandrel 203. The spinning raw material is added into the cavity of the spinning needle 201, and under the action of a booster (such as a micro injection pump), the spinning raw material is continuously, quantitatively and uniformly extruded from the spinneret orifice of the spinning needle 201, nano-sized or micron-sized fibers 202 are generated under the action of an electric field, the generated fibers 202 are uniformly deposited on the surface of the stent covered with the elastic coating 102 for collection, and finally the circumferentially oriented developable coating 103 is formed.

In another embodiment, the developable coating 103 is spun directly onto the mandrel 203, and the developable coating 103 is then placed over the stent. In a similar principle, the spinning raw material is added into the cavity of the spinning needle 201, and is continuously, quantitatively and uniformly extruded from the spinneret orifice of the spinning needle 201 under the action of the booster, nano-sized or micron-sized fibers 202 are generated under the action of an electric field, the generated fibers 202 are uniformly deposited on the surface of the mandrel 203 for collection, and finally the tubular developable coating 103 is formed, and then the tubular developable coating 103 is sleeved on the stent.

In other embodiments, the fiber collecting device may also include a flat plate, and the fiber 202 is collected by the flat plate to obtain the sheet-shaped developable coating 103, and then the sheet-shaped developable coating 103 is coated on the stent.

The spinning needle 201 may have various structures. As shown in fig. 6a, the spinning needle 201 is configured as a double-layer capillary 201b, that is, the spinning needle 201 provides an outer layer cavity and an inner layer cavity surrounded by the outer layer cavity, at this time, the inner layer cavity can be filled with core layer spinning raw materials (the core layer spinning raw materials include a polymer material and a developer), and the outer layer cavity can be filled with shell layer spinning raw materials (the shell layer spinning raw materials include a polymer material), at this time, under the action of a booster, the core layer spinning raw materials and the shell layer spinning raw materials are respectively extruded from a spinneret of the spinning needle 201 continuously, quantitatively and uniformly at a certain speed, and the extruded core layer spinning raw materials and shell layer spinning raw materials are mixed at the spinneret and generate a nano-sized or micron-sized double-layer fiber 202 under the action of an electric field. The axial cross section of the fiber 202 produced in this manner is shown in fig. 7a, in which the developer is uniformly dispersed in the inner layer 202b of the fiber 202, and the outer layer 202a of the fiber 202 does not contain any developer. Taking solution electrostatic spinning as an indication, the core layer spinning raw material comprises a high polymer material, a developer and a solvent, the developer and the high polymer material are dissolved in the solvent to obtain a core layer solution, the mass fraction of the core layer solution can be selected to be 10 wt% -15 wt%, and the mass ratio of the developer to the high polymer material in the core layer solution can be selected to be 1: 1-1: 9; meanwhile, the shell spinning raw material comprises a high polymer material and a developing agent, the high polymer material is dissolved in a solvent to obtain a shell solution, and the mass fraction of the shell solution can be selected to be 8 wt% -12 wt%. Further, the solution electrospinning process is preferably performed under the following conditions: the spinning voltage is 18-23 kv, the receiving distance is 15-25 cm, the extrusion speed of the nuclear layer spinning raw material is 0.4-1.5 ml/h, the extrusion speed of the shell layer spinning raw material is 0.7-1.5 ml/h, the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45% +/-5%. In an alternative embodiment, when performing melt electrospinning, the process conditions are preferably: the spinning voltage is 20-30 kv, the receiving distance is 10-20 cm, the extrusion speed of the core layer spinning raw material is 0.5-1.5 cm/min, the extrusion speed of the shell layer spinning raw material is 1-2 cm/min, the spinning environment temperature is not lower than the melting point temperature of the high polymer material, and the relative humidity is 20% +/-5%.

Or, as shown in fig. 6b, the spinning needle 201 is also configured as a double-layer capillary 201b, at this time, as shown by an arrow 301, the core layer solution can be eliminated, the gas carrying the developer is directly introduced into the inner layer cavity of the spinning needle 201, the shell layer spinning raw material is also added into the outer layer cavity of the spinning needle 201, during the spinning process, the shell layer spinning raw material is continuously, quantitatively and uniformly extruded from the spinneret orifice of the spinning needle 201 by the outer layer cavity under the action of the booster, meanwhile, the gas carrying the developer is continuously introduced into the inner layer cavity and is sprayed from the spinneret orifice, the gas and the shell layer spinning raw material are mixed at the spinneret orifice, and finally, the nano-sized or micron-sized double-layer fiber 202 can be produced under the action of the electric field. The axial cross section of the fiber 202 produced in this manner is shown in fig. 7b, the developer is distributed in powder form in the inner layer 202b of the hollow fiber, the outer layer 202a of the fiber does not contain the developer, and at this time, the inner layer 202b is entirely composed of the developer. Taking solution electrostatic spinning as an indication, the shell spinning raw materials comprise a high polymer material and a developer, the high polymer material is dissolved in a solvent to obtain a shell solution, and the mass fraction of the shell solution can be selected to be 8 wt% -12 wt%. Further, the solution electrospinning process is preferably performed under the following conditions: the spinning voltage is 15-25 kv, the receiving distance is 15-25 cm, the extrusion speed of the shell spinning raw material is 0.4-1.5 ml/h, the flow of the developing agent introduced into the inner layer cavity is 1-5 mg/h, the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45% +/-5%. In an alternative embodiment, the process conditions under which melt electrospinning is performed are preferably such that the spinning voltage is: 25 kv-35 kv, the receiving distance is 15 cm-25 cm, the extrusion speed of the shell layer spinning raw material is 0.5 cm/min-1.5 cm/min, the flow of the developing agent introduced into the inner layer cavity is 1 mg/min-10 mg/min, the spinning environment temperature is not lower than the melting point temperature of the high polymer material, and the relative humidity is 20% +/-5%. Furthermore, it is preferable that before the gas carrying the developer is introduced into the inner chamber, the developer is processed into powder, and dried and milled to prevent agglomeration.

By adopting the electrostatic spinning method, the developer can be solidified in the fiber, so that the fiber internally filled with the developer is prepared. More preferably, when the preparation method shown in fig. 2 is adopted, the inner diameter of the inner layer cavity is preferably 1/10-1/2 of the inner diameter of the outer layer cavity, and more preferably 1/4-1/2 of the inner diameter of the inner layer cavity, so that the size of the inner layer cavity is limited, the developer is better wrapped inside the fibers, and the developer is prevented from being precipitated. Or when the preparation method shown in fig. 3 is adopted, the inner diameter of the inner layer cavity is preferably 1/10-1/2 of the inner diameter of the outer layer cavity, more preferably 1/10-1/3 of the inner diameter of the inner layer cavity, and similarly, the size of the inner layer cavity is limited, so that the developer is better wrapped inside the fibers, and the developer is prevented from being precipitated.

In other embodiments, the spinning needle 201 may be configured to have three or more layers, wherein the outer layer cavity is a shell spinning raw material, and one or more inner layer cavities inside the outer layer cavity may be filled with a developing agent, so as to prepare three or more layers of fibers in the same manner. It will be appreciated that the wall thickness of the inner cavity of the double layer capillary is very small and essentially negligible.

Further, the developable film 103 may be distributed as shown in fig. 4a, that is, the developable film 103 covers the elastic film 102 entirely. Alternatively, as shown in fig. 8, the developable coating 103 covers the elastic coating 102 in a spiral winding manner to partially cover the elastic coating 102, and in this case, the developable coating 103 may have a spiral shape, a continuous strip, or a plurality of strips spaced apart from each other. Specifically, the original film may be prepared by cutting the original film into a spiral shape and then winding the cut film around the stent, or the original film may be covered with the elastic film and then cut into a spiral shape. As shown in fig. 9, the developable film 103 may be covered on the elastic film 102 in a ring-like winding manner, so as to partially cover the elastic film 102. Further, at least the developable coating 103 is provided at both ends of the stent to facilitate the determination of the boundary of the elastic coating 102. Similarly, if the developable coating 103 is distributed on the elastic coating 102 in a ring-segment manner, a sheet-shaped or tubular developable original coating can be prepared first, then the sheet-shaped or tubular original coating is cut into a ring-segment shape and then wound on the stent, or the sheet-shaped or tubular original coating can be covered on the elastic coating and then cut into a ring-segment shape. Preferably, the elastic coating 102 and the developable coating 103 are bonded by thermocompression bonding, or they may be bonded by a biocompatible adhesive, which does not affect the physical properties of the coating itself and prevents the coating from being damaged.

To understand the manufacturing process of the stent graft of the present invention in more detail, the following examples of the first to the fourth embodiments are further described, and the following description assumes that solution electrospinning and melt electrospinning are used for illustration, but should not be taken as a limitation of the present invention.

Example one

The embodiment provides a preparation method of a covered stent, which comprises the following steps:

first, a bare stent was prepared: and cutting the Co-Cr alloy L605 pipe into a tubular hollow structure to obtain the bare stent.

Then, a layer of PU film (namely, the material is polyurethane and does not contain a developer) is prepared on the outer side of the bare stent, and the thickness of the PU film can be 50-100 mu m.

Secondly, a layer of PU film containing a developer is prepared on the outer side of the PU film.

The preparation process of the PU film containing the developer comprises the following steps:

obtaining a shell layer solution: the shell solution comprises polyurethane and a solvent, wherein the solvent comprises acetone and N, N-dimethylformamide (DMF for short). And dissolving the polyurethane in a solvent to obtain a mixed solution, namely a shell solution, wherein the mass fraction of the shell solution is 8-12 wt%.

Obtaining a nuclear layer solution at the same time: the core layer solution comprises iohexol, polyurethane and a solvent, the solvent is acetone and N, N-dimethylformamide (DMF for short), the mass fraction of the core layer solution is 10 wt% -15 wt%, and the mass ratio of the iohexol to the polyurethane in the core layer solution is 1: 1-1: 9, for example, the mass ratio of the selected iohexol to the polyurethane is 1: 3 or 1:9, wherein the mass ratio of acetone to DMF is 1: 1-1: 19, such as the mass ratio of acetone to N, N-dimethylformamide is 1: 10. specifically, polyurethane is dissolved in a solvent to obtain a mixed solution, and iohexol is added to the mixed solution, and ultrasonic dispersion is performed to uniformly disperse the developer.

After obtaining the shell layer solution and the core layer solution, forming the fiber: the solution electrostatic spinning is carried out by using the forming device 20 shown in fig. 5, and the spinning solution is extruded through the spinning needle 201b shown in fig. 6a, and finally the double-layer fiber is formed, the structure of the double-layer fiber is shown in fig. 7a, the average diameter of the fiber is 600 nm-1200 nm, and the average diameter of the developer contained in the inner layer is 200 nm-400 nm.

Then, the developer-containing PU film was molded: continuously depositing the fibers obtained by the step on a stent rotating along with a mandrel 203, wherein the part of the stent which does not need to develop the PU film can be covered by a covering material (such as a sleeve), and the PU film containing the developing agent is finally obtained along with the continuous enrichment of the fibers on the stent covered with the film, and the average thickness of the PU film containing the developing agent is 25 mu m;

finally, the PU film containing the developer and the PU film without the developer are tightly adhered by a hot pressing method or an adhesive, wherein the hot pressing temperature is at least higher than the glass transition temperature of the high polymer material, for example, the temperature is controlled between 60 ℃ and 100 ℃, and finally the covered stent shown in the figure 4a and the figure 4b is obtained.

It is known that, in the electrospinning process, the main process parameters affecting the properties of the fibers are: polymer concentration, spinning voltage, take-up distance (nozzle to take-up distance), solvent properties, extrusion speed, etc., by optimizing these process parameters, the properties of the fiber can be improved.

In this embodiment, the process conditions for performing solution electrospinning are as follows: the spinning voltage is 20kv, the receiving distance is 18cm, the extrusion speed of the shell layer solution is 0.7ml/h, the extrusion speed of the core layer solution is 0.4ml/h, the ambient temperature is 25 ℃ +/-3 ℃, and the relative humidity is 45%. Here, the receiving distance is the distance between the spinning needle 201 and the mandrel 203, and the extruding speed is the flow rate of the spinning solution. In the spinning process, the environmental temperature is kept at 25 +/-3 ℃, the relative humidity is 45%, and the uniform volatilization of the solvent in the spinning process can be ensured, so that the formed fiber is more uniform and stable.

Further, in the first embodiment, the helical cover shown in FIG. 8 can be obtained by covering the portion of the stent graft where no cover is needed and cutting the edges of the cover and the developable cover.

Example two

Unlike the first embodiment, the process for preparing the developer-containing PU film includes:

prefabricating a bar: the PU is prefabricated into a rod-shaped material with the diameter of 1 mm-2 mm to be used as a shell material of the fiber, and 10-30 wt% of developer is added into the PU to prepare the rod-shaped material with the diameter of 1 mm-2 mm to be used as a core layer material of the fiber.

Forming fibers: melt electrospinning was carried out using the molding apparatus 20 shown in FIG. 5, and the molten polymer was extruded through the spinning needle 201b shown in FIG. 6a, to finally mold a double-layered fiber having a structure shown in FIG. 7a, the fiber having an average diameter of 800nm to 1500nm, wherein the developer-containing average diameter of the inner layer was 300nm to 500 nm.

It should be appreciated that in the melt electrospinning process, the molding apparatus 20 adds a heating device to the solution electrospinning and modifies the injection device so that it can inject the inner and outer rods. And the main process parameters influencing the fiber performance are as follows: heating temperature, spinning voltage, take-up distance (nozzle to take-up distance), extrusion speed, etc., by optimizing these process parameters, the properties of the fiber can be improved.

In this embodiment, the process conditions for performing melt electrospinning are as follows: the spinning voltage is 30kv, the receiving distance is 18cm, the extrusion speed of the shell layer polymer is 1.2cm/min, the extrusion speed of the core layer material is 0.8cm/min, the spinning environment temperature is 180 ℃, and the relative humidity is 20%. Here, the receiving distance is the distance between the spinning needle 201 and the mandrel 203, and the extruding speed is the advancing speed of the bar.

EXAMPLE III

The preparation method of the stent graft of the embodiment comprises the following steps:

firstly, preparing a naked stent: cutting a PLLA (L-polylactic acid) pipe into a tubular hollow structure to obtain a bare stent, and adding a developing point on the bare stent to mark the position of the stent.

Then, a degradable polylactic acid film with a thickness of 60 μm was prepared on the outer side of the bare stent.

And secondly, preparing a layer of polylactic acid film containing the developer on the outer side of the polylactic acid film.

Wherein the preparation process of the developer-containing polylactic acid film comprises the following steps:

firstly, obtaining a shell layer solution: the shell solution comprises polylactic acid and a solvent, and the solvent comprises acetone and chloroform. Specifically, polylactic acid is dissolved in a solvent to obtain a shell solution, and the volume ratio of acetone to chloroform is 1: 2. also provided is the ionic developer diatrizoate.

Then forming the fiber: the solution electrospinning is performed using the molding apparatus 20 shown in fig. 5, and the spinning solution is extruded through the spinning needle 201b shown in fig. 6 b. Specifically, inert gas carrying the developer is blown into the inner layer cavity at a certain speed, meanwhile, the shell layer solution in the outer layer cavity is extruded at a certain speed, finally, the inert gas is mixed with the polylactic acid solution at the spinneret orifice to obtain the double-layer fiber, the structure of the double-layer fiber is shown in fig. 7b, and the average diameter of the double-layer fiber is 450 nm.

Then, the developer-containing polylactic acid film is molded: the fibers obtained by the molding in the above steps are continuously deposited on the rotating mandrel 203, and as the fibers are continuously enriched on the mandrel 203, a tubular polylactic acid film containing the developer is finally obtained, wherein the average thickness of the polylactic acid film containing the developer is 18 μm.

Then cutting the tubular polylactic acid film containing the developer into a ring-shaped ring, and sleeving the ring-shaped polylactic acid film on the degradable polylactic acid film.

And finally, bonding and fixing the degradable polylactic acid film and the polylactic acid film containing the developer by using a biocompatible adhesive to obtain the covered stent shown in figure 9.

In example three, the developer powder was pre-dried and milled to prevent agglomeration. Further, the process conditions for performing the solution electrospinning are preferably: the flow rate of the developing agent introduced into the inner layer cavity is preferably 1 mg/h-5 mg/h, the spinning voltage is 15kv, the receiving distance is 15cm, the extrusion speed of the shell layer solution is 1.2ml/h, the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45%.

Example four

Unlike in example three, the process for producing a developer-containing polylactic acid film comprises:

prefabricating a bar: PU is prefabricated into a rod-shaped material with the diameter of 1 mm-2 mm to be used as a shell material of the fiber.

Forming fibers: melt electrospinning is carried out by using the molding apparatus 20 shown in FIG. 5, and the molten polymer is extruded through the spinning needle 201b shown in FIG. 6b, and finally molded to obtain a double-layer fiber having a structure shown in FIG. 7b, wherein the average diameter of the fiber is 800nm to 1500 nm.

It should be appreciated that the forming apparatus 20 also adds a heating device and improves a pushing device to uniformly push the rod material based on the solution electrospinning in the melt electrospinning process. The main process parameters affecting the fiber properties are: heating temperature, spinning voltage, take-up distance (nozzle to take-up distance), extrusion speed, etc., by optimizing these process parameters, the properties of the fiber can be improved.

In this embodiment, the process conditions for performing melt electrospinning are as follows: the spinning voltage is 30kv, the receiving distance is 18cm, the extrusion speed of the shell layer macromolecule is 1.2cm/min, the flow of the developer is 2mg/min, the spinning environment temperature is 180 ℃, and the relative humidity is 20%. Here, the receiving distance is the distance between the spinning needle 201 and the mandrel 203, and the extruding speed is the advancing speed of the bar.

Further, the stent graft prepared in the above example was simulated in vitro, and the durability and stability of the development were confirmed. Specifically, the stent graft of the above example was implanted into an animal, a puncture of about 1mm was made in the coronary artery of a pig, and the stent graft was implanted at the position of the puncture. Furthermore, under X-ray, the blood does not leak to the surrounding tissue due to the occlusion of the coating at the hole, and the coating can be clearly observed. The follow-up at 3, 6 and 12 months after the operation, except that the development performance of the covered stent of the embodiment 3 is reduced at 6 months after the operation due to degradation, the development performance of the covered stent of the embodiment 1 and the embodiment 2 is not obviously changed, and no animal adverse reaction is seen in the covered stent in the test period. Therefore, the stent graft prepared by the embodiment of the invention has lasting developability and good development stability, and effective developing components (including developers with high activity) are distributed in the fiber and do not dissociate on the surface of the fiber, so that the harm to human bodies caused by the precipitation of the developers is reduced, the safety is good, and certain developers with higher activity, such as nano-scale developers, can be coated in the fiber to ensure the stability of the developers, therefore, the scope of the selectable developers is wide, and the preparation cost can be further reduced.

It should be understood that the stent graft of the present invention is not only suitable for treating coronary artery perforation and aneurysm, but also can be used in all body lumens, such as veins, main abdominal arteries, etc., which need isolation, drainage, support, etc.

It should be understood that the above-described embodiments specifically disclose features of preferred embodiments of the present invention so that those skilled in the art may better understand the present invention. Those skilled in the art will appreciate that the present invention is susceptible to considerable modification based on the disclosure herein, to achieve the same objects and/or achieve the same advantages as the disclosed embodiments of the present invention. Those skilled in the art should also realize that such similar constructions do not depart from the scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the scope of the present disclosure.

Claims

1. A method of making a fiber for making a multilayer fiber, comprising:

2. The method of claim 1, wherein the step of electrospinning to obtain a fiber having an inner layer containing a developer comprises:

3. The method of claim 1, wherein the step of electrospinning to obtain a fiber having an inner layer containing a developer comprises:

4. The method for preparing the fiber according to claim 2, wherein the inner diameter of the inner layer cavity is 1/10-1/2 of the inner diameter of the outer layer cavity.

5. The method for preparing the fiber according to claim 4, wherein the inner diameter of the inner layer cavity is 1/4-1/2 of the inner diameter of the outer layer cavity.

6. A method of producing a fibre according to claim 3 wherein the gas is an inert gas.

7. The method for preparing the fiber according to claim 3, wherein the inner diameter of the inner layer cavity is 1/10-1/2 of the inner diameter of the outer layer cavity.

8. The method for preparing the fiber according to claim 7, wherein the inner diameter of the inner layer cavity is 1/10-1/3 of the inner diameter of the outer layer cavity.

9. The method of claim 3, wherein before the step of introducing the developer-carrying gas into the inner cavity, the method further comprises: the developer is processed into powder, dried and milled.

10. The method of claim 2, wherein the electrospinning is solution electrospinning and the process conditions include: the spinning voltage is 18 kv-23 kv; the receiving distance is 15 cm-25 cm; the extrusion speed of the core layer spinning raw material is 0.4 ml/h-1.5 ml/h; the extrusion speed of the shell layer spinning raw material is 0.7 ml/h-1.5 ml/h; the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45% +/-5%; or the electrostatic spinning is melt electrostatic spinning, and the execution process conditions comprise: the spinning voltage is 20 kv-30 kv; the receiving distance is 10 cm-20 cm; the extrusion speed of the core layer spinning raw material is 0.5 cm/min-1.5 cm/min; the extrusion speed of the shell layer spinning raw material is 1 cm/min-2 cm/min, the spinning environment temperature is not lower than the melting point temperature of the high polymer material, and the relative humidity is 20% +/-5%.

11. The method of claim 3, wherein the electrospinning is solution electrospinning and the process conditions include: the spinning voltage is 15 kv-25 kv; the receiving distance is 15 cm-25 cm; the extrusion speed of the shell layer spinning raw material is 0.4 ml/h-1.5 ml/h; the flow rate of the developer introduced into the inner layer cavity is 1 mg/h-5 mg/h; the spinning environment temperature is 25 +/-3 ℃, and the relative humidity is 45% +/-5%; or the electrostatic spinning is melt electrostatic spinning, and the execution process conditions comprise: the spinning voltage is 25 kv-35 kv; the receiving distance is 15 cm-25 cm; the extrusion speed of the shell layer spinning raw material is 0.5 cm/min-1.5 cm/min; the flow of the developer introduced into the inner layer cavity is 1 mg/min-10 mg/min; the temperature of the spinning environment is not lower than the melting point temperature of the high polymer material, and the relative humidity is 20 +/-5%.

12. A fiber produced by the method of producing a fiber according to any one of claims 1 to 11.

13. A coating film, characterized by being prepared from a fiber prepared by the method for preparing the fiber according to any one of claims 1 to 11 or a fabric made of the fiber.

14. A preparation method of a covered stent is characterized by comprising the following steps:

preparing a developable coating by using the fiber or the fabric made of the fiber according to claim 12, and covering the surface of the stent body with the developable coating.

15. The method of preparing a stent graft as recited in claim 14, wherein the step of covering the stent body with the developable coating includes:

16. The method of preparing a stent graft as recited in claim 14, wherein the step of covering the stent body with the developable coating includes:

17. The method of preparing a stent graft of claim 15, further comprising, prior to depositing the fibers onto the stent body: covering a portion of the stent body with a cover;

18. The method for preparing a stent graft according to claim 14, wherein the stent body is a bare stent or a stent graft covered with an elastic covering film; when the stent body is a covered stent, the developable covering film is combined with the elastic covering film through physical acting force.

19. The method of claim 18, wherein the developable coating is bonded to the elastic coating using a thermal compression process or bonded to the elastic coating with an adhesive.

20. The covered stent is characterized by comprising a stent body and a developable covering film, wherein the developable covering film covers the surface of the stent body; the developable coating is prepared from fibers, the fibers comprise an outer layer and at least one inner layer, the outer layer is composed of a high polymer material, and the inner layer contains a developer or contains a developer and a high polymer material.

21. The stent graft of claim 20, wherein the stent body is a bare stent or the stent body is a stent graft covered with an elastic covering membrane.

22. The stent graft of claim 21, wherein the developable coating at least partially covers the elastic coating when the stent body is a stent graft.

23. The stent graft of claim 22, wherein the developable coating is in the shape of a helix or a ring.

24. The stent graft of claim 20, wherein the developer is a heavy metal-containing developer, an ionic developer or a non-ionic developer.

25. The stent graft of claim 24, wherein the heavy metal-containing imaging agent is selected from barium sulfate or nano-metal particles; the ionic developer is selected from one or more of iodic acid, diatrizoate, diatrizoic acid, iothalamate and iophthalate; the non-ionic developer is one or more of iohexol, iomeprol, ioseptitol, ioversol, iopromide, iopamidol, ioversol, iotrolan and iodixanol.