WO2022077878A1

WO2022077878A1 - Silk protein nerve conduit and preparation method therefor

Info

Publication number: WO2022077878A1
Application number: PCT/CN2021/086167
Authority: WO
Inventors: 吕强; 路青青; 张锋
Original assignee: 苏州大学
Priority date: 2020-10-15
Filing date: 2021-04-09
Publication date: 2022-04-21
Also published as: CN112263714B; CN112263714A

Abstract

Provided in the present invention is a silk protein nerve conduit, comprising a conduit portion and a filling sponge filled within the conduit portion. The conduit portion comprises a conduit base and a silk protein thin film compounded on the surface of the conduit base. The conduit base is formed by means of weaving silk protein fibers. The filling sponge is formed by means of a silk protein nanofiber gel with an oriented structure. Compared with the prior art, the silk protein nerve conduit of the present invention has an orientation structure consistent with the neuro-axial direction by means of arranging the silk protein nanofiber sponge with the oriented structure inside the conduit, can provide an orientation-inducing signal, promote the migration and proliferation of nerve cells, can also guide the regeneration and extension of nerve fibers and significantly improve the function of the neural conduit. Therefore, the problems of mechanical performance and orientation induction are solved in the present invention by means of the combination of a silk protein tube and the silk protein oriented sponge.

Description

A kind of silk protein nerve conduit and preparation method thereof

This application claims the priority of the Chinese patent application filed on October 15, 2020 with the application number 202011102746.5 and titled "A silk protein nerve conduit and its preparation method", the entire contents of which are incorporated by reference in in this application.

technical field

The invention belongs to the technical field of biomedical materials, and in particular relates to a silk protein nerve conduit and a preparation method thereof.

Background technique

Peripheral nerve injury is a common clinical condition, and autologous transplantation is often used to bridge peripheral nerve defects. However, limited availability and donor site morbidity still exist, so to overcome this limitation, researchers developed biomaterial-based nerve conduits to assist peripheral nerve regeneration. Artificial conduits have been shown to have the ability to fill nerve gaps, synthetic nerve conduits are expected to replace autografts, and improvements in biomaterials hold great potential for promoting nerve regeneration and functional recovery. Therefore, the developed nerve conduit not only has good biological properties, but also should provide a better microenvironment for the regeneration of nerve tissue.

At present, there are many nerve conduits made of different materials, and relatively good results have been achieved in animal experiments and clinical studies. However, compared with autologous nerve conduits, there is still a big gap in their performance. How to introduce different induction signals into the design of the nerve conduit according to the bionic concept is an effective way to further optimize the function of the nerve conduit and improve the repair of peripheral nerve damage.

Silk protein has been widely used in the repair and regeneration of different tissues due to its excellent biocompatibility, degradability, and low inflammatory response, and good early results have also been obtained in the field of neuroreparation. However, how to use silk protein as a matrix? However, there are still large technical obstacles to realize the active introduction of different inducing signals. At present, researchers mainly use electrospinning technology and directional freezing technology to achieve the introduction of orientation signals. There are major problems in the effective combination with nerve conduits and the stability of the technology. New preparation methods need to be considered to obtain better orientation induction. Signaling of silk protein conduits.

In the research of our team, by combining silk protein weaving technology and silk protein film forming technology, a composite catheter with good mechanical properties was successfully obtained and applied to the replacement of small blood vessels. However, due to the instability of silk protein solution , how to stably obtain water-insoluble silk protein fiber-film composite catheters still requires technical improvements and breakthroughs on the basis of understanding the mechanism of silk protein; in addition, we successfully obtained the directional structure of silk protein nanofibers through electric field-induced directional migration. Silk protein gel or sponge has been successfully applied to wound repair and induced migration of nerve cells. However, the above-mentioned gel or sponge has poor mechanical properties and is difficult to meet the requirements of clinical application. Therefore, the present invention is based on the team's deep understanding of silk protein. It is hoped that through the combination and optimization of different technologies, a composite nerve conduit with excellent mechanical properties on the outside and meeting application requirements, and an oriented silk protein sponge on the inside to provide orientation-inducing signals can be prepared to achieve better repair effect. The key of the present invention is not only to solve the problem of stable acquisition of the insolubility of the silk protein braided tube and the silk protein film in the aqueous environment, but also to solve the technical problem of the efficient introduction of the oriented sponge into the catheter.

SUMMARY OF THE INVENTION

In view of this, the technical problem to be solved by the present invention is to provide a silk protein nerve conduit with an orientation-inducing signal and a preparation method thereof.

The invention provides a silk protein nerve conduit, comprising: a conduit part and a filling sponge filled in the conduit part; the conduit part comprises a conduit base and a silk protein film compounded on the surface of the conduit base; the conduit base is made of silk protein The fibers are woven and formed; the filling sponge is formed of a silk protein nanofiber gel with an oriented structure.

The present invention also provides a preparation method of silk protein nerve conduit, comprising:

S1) weaving silk protein fibers to obtain a catheter matrix;

S2) soaking the catheter matrix in the silk protein solution to obtain the catheter part;

S3) combining the silk protein nanofiber gel with an oriented structure with the catheter part, and after freeze-drying, the silk protein nerve catheter is obtained.

Preferably, the fibroin fiber is 80-100 denier degummed silk; the braiding angle is 45°-60°; the braiding speed is 30-60 r/min; the inner diameter of the catheter base is 0.5-15 mm.

Preferably, the concentration of silk protein in the silk protein solution is 2-10 wt%; the silk protein comprises silk protein nanofibers; the mass of the silk protein nanofibers is 0%-40% of the mass of the silk protein.

Preferably, the silk protein nanofibers have a diameter of 10-20 nm and a length of 1-2 μm.

Preferably, described S2) is specifically:

The catheter substrate is soaked in the silk protein solution and evaporated at 10°C to 90°C to obtain the catheter part.

Preferably, the silk protein nanofiber gel is prepared according to the following steps:

Concentrating the silk protein nanofiber aqueous solution at 40°C to 60°C to a first silk protein nanofiber aqueous solution with a concentration of 6 to 12wt%;

Concentrating the first silk protein nanofiber aqueous solution at 20°C to 35°C to a second silk protein nanofiber aqueous solution with a concentration of 18 to 24 wt %;

The second silk protein nanofiber aqueous solution is diluted with water to a third silk protein nanofiber aqueous solution with a concentration of 0.2-4wt%, and then sealed and incubated at 50°C to 70°C to obtain a silk protein nanofiber gel.

Preferably, the step S3) is specifically:

The silk protein nanofiber gel is induced by an electric field to obtain a silk protein nanofiber gel with an oriented structure;

Then the catheter part is inserted into the silk protein nanofiber gel with an oriented structure along the orientation direction, so that the catheter part is filled, and after being taken out, freeze-dried to obtain the silk protein nerve catheter;

Or: the catheter part is immersed in the silk protein nanofiber gel along the direction parallel to the electrode, and then subjected to electric field treatment, and after being taken out, freeze-dried to obtain the silk protein nerve catheter.

Preferably, the electric field strengths of the electric field induction and electric field treatment are each independently 10-120V; and the time is each independently 5-60min.

Preferably, the freeze-drying is specifically: firstly freeze at -20°C to -50°C for 1 to 12 hours, and then freeze-dry at -2°C to -90°C for 24 to 72 hours.

The invention provides a silk protein nerve conduit, comprising: a conduit part and a filling sponge filled in the conduit part; the conduit part comprises a conduit base and a silk protein film compounded on the surface of the conduit base; the conduit base is made of silk protein The fibers are woven and formed; the filling sponge is formed of a silk protein nanofiber gel with an oriented structure. Compared with the prior art, in the present invention, a silk protein nanofiber sponge with an oriented structure is arranged inside the catheter, and has an oriented structure consistent with the direction of the nerve axon, which can provide an orientation inducing signal, promote the migration and increase of nerve cells, and can also provide an orientation-inducing signal. It guides the regeneration and extension of nerve fibers and significantly improves the function of nerve conduits; therefore, the present invention solves the problems of mechanical properties and orientation induction through the combination of silk protein tubes and silk protein orientation sponges.

Description of drawings

Fig. 1 is the scanning electron microscope picture of the braided catheter obtained in the step (1) of the embodiment of the present invention 1;

2 is a scanning electron microscope image of the silk protein fiber-silk protein membrane composite catheter obtained in step (2) of Example 1 of the present invention;

Fig. 3 is the scanning electron microscope picture of the silk protein nerve conduit obtained in the embodiment of the present invention 2;

Fig. 4 is the scanning electron microscope image of the oriented silk protein sponge inside the silk protein nerve conduit obtained in Example 3 of the present invention;

Figure 5 is an electrophysiological waveform diagram of the regenerated nerve and autologous transplantation after the silk protein nerve conduit obtained in Example 3 of the present invention was transplanted into the rat sciatic nerve defect.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The invention improves the mechanical properties of the catheter by compounding the silk protein film on the surface of the catheter matrix formed by weaving the silk protein fibers; the silk protein nanofiber sponge with the orientation structure is arranged inside the catheter, and the orientation structure is consistent with the direction of the nerve axon. It can provide orientation-inducing signals, promote the migration and proliferation of nerve cells, and also guide the regeneration and extension of nerve fibers, significantly improving the function of nerve conduits; therefore, the present invention solves mechanical properties and orientation through the combination of silk protein tubes and silk protein orientation sponges. induced problems.

The present invention also provides a method for preparing the above silk protein nerve conduit, comprising: S1) weaving silk protein fibers to obtain a conduit matrix; S2) soaking the conduit matrix in a silk protein solution to obtain a conduit portion; S3) The silk protein nanofiber gel with oriented structure is combined with the conduit part, and after freeze-drying, the silk protein nerve conduit is obtained.

The present invention does not have any special restrictions on the sources of all raw materials, which can be commercially available.

The fibroin fiber is braided to obtain a catheter matrix; the fibroin fiber is preferably silk, more preferably degummed silk, and more preferably degummed silk of 80-100 deniers; the braiding angle of the braiding is preferably 45°～60°; The speed of the weaving is preferably 30-60r/min, more preferably 40-50r/min, and more preferably 45r/min; the gear ratio during the weaving is preferably (60-100): (20-60), more preferably It is preferably (70-90):(30-50), more preferably 80:40; the woven skeleton structure is preferably a knitted structure or a woven structure; the weaving is preferably performed on a smooth metal mold; the smooth metal The diameter of the mold is preferably 0.5 to 15 mm, so that the inner diameter of the resulting catheter base is preferably 0.5 to 15 mm.

The catheter substrate is soaked in the silk protein solution, preferably the catheter substrate with the mold is soaked in the silk protein solution; the concentration of the silk protein in the silk protein solution is preferably 2-10wt%; In the embodiments, the concentration of the silk protein solution is preferably 2wt%; in some embodiments provided by the present invention, the concentration of the silk protein solution is preferably 5wt%; in other embodiments provided by the present invention, the The concentration of the silk protein solution is preferably 10wt%; the silk protein in the silk protein solution includes silk protein nanofibers; the quality of the silk protein nanofibers is preferably 0% to 40% of the total mass of the silk protein, more preferably 0.5% to 30% of the total mass of silk protein, preferably 0.5% to 10% of the total mass of silk protein, most preferably 0.8% to 4% of the total mass of silk protein; use silk protein nanofibers to induce the conformational transition of ordinary silk protein The diameter of the silk protein nanofibers is preferably 10-20 nm; the length of the silk protein nanofibers is preferably 1-2 μm; the volume ratio of the catheter matrix to the silk protein solution is preferably 1: (1.5-3) , more preferably 1:(2～2.5), more preferably 1:2; soak the catheter matrix in the silk protein solution, preferably evaporate at 10℃～90℃, with the slow evaporation of water in the silk protein solution, it will A layer of insoluble silk protein film is formed on the catheter substrate, and the conformational transition rate of silk protein is regulated by the synergistic effect of nanofiber induction and temperature induction, and finally the film is stabilized in water. The conduit portion of a stable nerve conduit.

The silk protein nanofiber gel with an orientation structure is combined with the catheter part; in the present invention, the combination can be performed according to the following method: the silk protein nanofiber gel is induced by an electric field to obtain a silk protein nanofiber gel with an orientation structure. Then insert the catheter part into the silk protein nanofiber gel with the orientation structure along the orientation direction, so that it fills the catheter part; wherein, the silk protein nanofiber gel is preferably carried out according to the following steps: the silk protein nanofiber The aqueous solution is concentrated at 40°C to 60°C to a first silk protein nanofiber aqueous solution with a concentration of 6-12wt%; the first silk protein nanofiber aqueous solution is concentrated at 20°C to 35°C to a concentration of 18-24wt% of the second silk protein Nanofiber aqueous solution; dilute the second silk protein nanofiber aqueous solution with water to a third silk protein nanofiber aqueous solution with a concentration of 0.2-4wt%, and then seal and incubate at 50°C to 70°C to obtain a silk protein nanofiber gel; The silk protein nanofibers are the same as described above, and will not be repeated here; the electric field strength induced by the electric field is preferably 10-120V, more preferably 10-100V; the electric field-induced time is preferably 5-60min; then use The difference in the mechanical properties of the catheter part and the gel, the catheter part was inserted into the silk protein nanofiber gel with an oriented structure along the gel orientation direction, so that the gel filled the catheter.

Or combined according to the following steps: the catheter part is immersed in the silk protein nanofiber gel along the direction parallel to the electrode, and then electric field treatment is performed; the silk protein nanofiber gel is as described above, and will not be repeated here; The intensity of the electric field treatment is preferably 10-120V; the time of the electric field treatment is preferably 5-60min; the electric field treatment makes the nanofibers inside the conduit move directionally, and forms an orientation gel in the portion near the positive electrode inside the conduit, which occupies The volume is about 1/3, and it is preferable to repeat the above steps of immersion and electric field treatment until the silk protein nanofiber gel with oriented structure fills more than 90% of the catheter part.

After the silk protein nanofiber gel with an oriented structure is combined with the catheter part, freeze-drying is performed to obtain a silk protein nerve catheter; the freeze-drying is preferably specifically: firstly freeze at -20°C to -50°C for 1 to 12 hours, and then freeze at -20°C to -50°C for 1 to 12 hours. -2℃～-90℃ freeze drying for 24～72h. Through freeze-drying, the gel is transformed into a porous sponge with an oriented structure, and finally a composite nerve conduit with a conduit on the outside and an oriented sponge on the inside is obtained.

The silk protein nerve conduit prepared by the invention does not add any toxic substances, all its components are natural proteins, and have good compatibility; and by regulating the conformational transition rate of the silk protein, the water-insoluble silk protein fiber can be directly and stably obtained in an aqueous solution. -The catheter part of the film composite improves the mechanical properties of the catheter and makes it meet the needs of clinical applications. The interior of the catheter is an oriented silk protein nanofiber sponge, which has an oriented structure consistent with the direction of the nerve axon, which can provide orientation-inducing signals and promote neural The migration and proliferation of cells can also guide the regeneration and extension of nerve fibers, and significantly improve the function of nerve conduits; through the combination of silk protein tubes and silk protein orientation sponges, the problems of mechanical properties and orientation induction are solved; All are based on the basic physical treatment process, there is no chemical reaction and harsh preparation conditions, which is conducive to the industrial transformation and functional enrichment of the technology. Although it is a mild physical control, its related parameters and key steps of process integration are all based on silk protein. The in-depth understanding of the essence, especially the in-depth understanding of the silk protein assembly mechanism, the integration of different parameters jointly determines the final performance of the catheter, rather than the list of simple physical methods, so the technology has significant innovation.

In order to further illustrate the present invention, the silk protein nerve conduit provided by the present invention and its preparation method are described in detail below with reference to the examples.

The reagents used in the following examples are all commercially available.

The silk protein nanofibers used in the examples have a diameter of 10 nm and a length of 1 μm;

In the embodiment, the preparation method of the silk protein nanofiber gel is as follows: the silk protein nanofibers (10-20 nm in diameter, 1-2 μm in length) are concentrated into an aqueous solution at 40° C. to 60° C. to a first silk with a concentration of 6-12 wt %. Protein nanofiber aqueous solution; concentrate the first silk protein nanofiber aqueous solution at 20°C to 35°C to a second silk protein nanofiber aqueous solution with a concentration of 18-24 wt %; dilute the second silk protein nanofiber aqueous solution with water to the concentration A 0.2-4wt% aqueous solution of the third silk protein nanofibers, and then sealed and incubated at 50°C to 70°C to obtain a silk protein nanofiber gel;

The silk protein in the described embodiment can be prepared according to Reversible Hydrogel-Solution System of Silk with High Beta-Sheet Content (Biomacromolecules 2014, 15, 3044-3051).

Example 1

(1) Select a smooth first die with a diameter of 3mm, degumming silk with a 100-denier cooked silk thread, and weave a skeleton structure on it by a textile machine, the weaving angle is 45°, the speed is 45r/min, and the gear ratio is 80:40 ; The braided skeleton structure is a braided structure.

(2) The braided catheter is completely immersed in a 2% silk protein aqueous solution (the content of silk protein nanofibers is 0.8% of the total mass of silk protein), and the volume ratio of the catheter to the silk protein aqueous solution is 1:2. Under certain conditions, with the slow evaporation of water in the silk protein solution, an insoluble silk fibroin film will be formed on the skeleton to obtain a silk protein fiber-silk protein film composite conduit.

(3) Preparation of 0.2% oriented silk protein nanofiber gel, the basic parameters of electric field induction are: electric field intensity 10V, treatment time 5 minutes. The fibroin fiber-fibroin membrane composite catheter was then inserted into the gel matrix along the orientation direction, so that the gel filled the interior of the catheter. Put it into a -20°C refrigerator to freeze overnight, and then put it into a freeze dryer at -80°C for 48 hours to freeze-dry it and take out to obtain a silk protein nerve conduit filled with an oriented silk protein sponge.

The braided catheter obtained in step (1) is analyzed with a scanning electron microscope, and its scanning electron microscope image is obtained, as shown in FIG. 1 .

The fibroin fiber-fibroin membrane composite conduit obtained in step (2) is analyzed by scanning electron microscope, and its scanning electron microscope image is obtained, as shown in FIG. 2 .

Example 2

(1) Select a smooth first die with a diameter of 5mm, degummed silk with 100 denier of cooked silk thread, and weave a skeleton structure on it by a textile machine, the weaving angle is 60°, the speed is 45r/min, and the gear ratio is 80:40 ; The braided skeleton structure is a braided structure.

(2) The braided catheter is completely immersed in a 10% silk protein solution (the content of silk protein nanofibers is 4% of the silk protein mass), and the volume ratio of the catheter to the silk protein aqueous solution is 1:2. Under the conditions, along with the slow evaporation of water in the silk fibroin solution, an insoluble silk fibroin film will be formed on the skeleton to obtain a silk protein fiber-silk protein film composite conduit.

(3) The catheter was placed in a direction parallel to the electrodes and immersed in 4% silk protein nanofiber gel, and then the gel was subjected to electric field treatment, the electric field strength was 100V, and the treatment time was 30min, so as to make the nanofibers inside the catheter move directionally , and the oriented gel is formed in the part near the positive electrode inside the catheter, which occupies about 1/3 of the volume, and then continues to be filled with gel in the part of the catheter without oriented gel, and the electric field treatment process is repeated until more than 90% of the space is filled with gel. The orientation gel occupies, the catheter is removed, and the composite catheter is obtained. Put it in a -20°C refrigerator overnight, and then put it in a freeze dryer at -50°C for 48 hours to freeze-dry it out to convert the gel into an orientation sponge, and finally obtain a silk protein nerve conduit with an orientation signal.

The silk protein nerve conduit obtained in Example 2 was analyzed by scanning electron microscope, and its scanning electron microscope image was obtained, as shown in FIG. 3 .

Example 3

(1) Select a smooth first die with a diameter of 10mm, degummed silk with a 100-denier cooked silk thread, and weave a skeleton structure on it by a textile machine. The weaving angle is 60°, the speed is 45r/min, and the gear ratio is 80:40 ; The braided skeleton structure is a braided structure.

(2) The braided catheter is completely immersed in 5% silk protein solution (the content of silk protein nanofibers is 2% of the total mass of silk protein), and the volume ratio of the catheter to the silk protein aqueous solution is 1:2. Under certain conditions, with the slow evaporation of water in the silk fibroin solution, an insoluble silk fibroin film will be formed on the skeleton to obtain a silk protein fiber-silk protein film composite conduit.

(3) Preparation of 4% oriented silk protein nanofiber gel, the basic parameters of electric field induction are: electric field intensity 100V, treatment time 60min. The composite fibroin conduit was then inserted into the gel matrix along the orientation direction so that the gel filled the interior of the conduit. Put it into a -20°C refrigerator to freeze overnight, and then put it into a freeze dryer at -80°C for 48 hours to freeze-dry it and take out to obtain a silk protein nerve conduit filled with an oriented silk protein sponge.

The silk protein nerve conduit obtained in Example 3 was analyzed with a scanning electron microscope, and a scanning electron microscope image of the internally oriented silk protein sponge was obtained, as shown in FIG. 4 .

Figure 5 shows the electrophysiological waveforms of regenerated nerves and autologous transplantation after the silk protein nerve conduit obtained in Example 3 was transplanted into the rat sciatic nerve defect. Electrical signaling was detected 12 weeks after nerve conduit transplantation into the rat defect.

In summary, the present invention discloses an oriented silk fibroin nerve conduit and a preparation method thereof. Starting from the design of materials and biomimetic structures, a nerve conduit which is respectively composed of a silk-based conduit and an oriented silk protein nanofiber scaffold is designed. The silk protein conduit reinforced by silk woven fibers is filled with silk protein gel with an orientation structure, and the gel is transformed into an orientation sponge by freeze-drying technology to obtain a nerve conduit with orientation-inducing signals. The preparation process of the invention has mild conditions, and innovatively combines different silk protein preparation technologies to obtain a nerve conduit with orientation signals and mechanical properties that meet application requirements.

Claims

A silk protein nerve conduit, characterized in that it comprises: a conduit part and a filling sponge filled in the conduit part; the conduit part comprises a conduit base and a silk protein film compounded on the surface of the conduit base; the conduit base is made of silk protein The fibers are woven and formed; the filling sponge is formed of a silk protein nanofiber gel with an oriented structure.
A preparation method of silk protein nerve conduit, is characterized in that, comprises:

S1) weaving silk protein fibers to obtain a catheter matrix;

S2) soaking the catheter matrix in the silk protein solution to obtain the catheter part;

S3) combining the silk protein nanofiber gel with an oriented structure with the catheter part, and after freeze-drying, the silk protein nerve catheter is obtained.
The preparation method according to claim 2, wherein the fibroin fiber is 80-100 denier degummed silk; the weaving angle of the weaving is 45°-60°; the weaving speed is 30-60 r/min; The inner diameter of the catheter base body is 0.5-15 mm.
The preparation method according to claim 2, wherein the concentration of silk protein in the silk protein solution is 2-10 wt%; the silk protein comprises silk protein nanofibers; the quality of the silk protein nanofibers is silk 0% to 40% of the protein content.
The preparation method according to claim 3, wherein the silk protein nanofibers have a diameter of 10-20 nm and a length of 1-2 μm.
preparation method according to claim 2, is characterized in that, described S2) is specially:

The catheter substrate is soaked in the silk protein solution and evaporated at 10°C to 90°C to obtain the catheter part.
The preparation method according to claim 2, wherein the silk protein nanofiber gel is prepared according to the following steps:

Concentrating the silk protein nanofiber aqueous solution at 40°C to 60°C to a first silk protein nanofiber aqueous solution with a concentration of 6 to 12wt%;

Concentrating the first silk protein nanofiber aqueous solution at 20°C to 35°C to a second silk protein nanofiber aqueous solution with a concentration of 18 to 24 wt %;

The second silk protein nanofiber aqueous solution is diluted with water to a third silk protein nanofiber aqueous solution with a concentration of 0.2-4wt%, and then sealed and incubated at 50°C to 70°C to obtain a silk protein nanofiber gel.
The preparation method according to claim 2, wherein the step S3) is specifically:

The silk protein nanofiber gel is induced by an electric field to obtain a silk protein nanofiber gel with an oriented structure;

Then, the catheter part is inserted into the silk protein nanofiber gel with an oriented structure along the orientation direction, so that the catheter part is filled, and after being taken out, freeze-drying is performed to obtain the silk protein nerve catheter;

Or: the catheter part is immersed in the silk protein nanofiber gel along the direction parallel to the electrode, then subjected to electric field treatment, taken out, and freeze-dried to obtain the silk protein nerve catheter.
The preparation method according to claim 8, wherein the electric field strengths of the electric field induction and the electric field treatment are independently 10-120V, and the time is independently 5-60min.
The preparation method according to claim 2, wherein the freeze-drying is specifically: firstly freeze-drying at -20°C～-50°C for 1～12h, and then freeze-drying at -2°C～-90°C for 24～72h .