Fabric reinforced electroactive nerve conduit and preparation method and application thereof

Abstract

The invention provides a fabric-reinforced electroactive nerve conduit and a preparation method and application thereof, and belongs to the field of biomedical materials.The fabric-reinforced electroactive nerve conduit comprises a nerve conduit inner layer and a nerve conduit outer layer, the nerve conduit inner layer is a woven skeleton formed by magnesium wires serving as parallel yarns and degummed silk through a three-dimensional weaving process, the pore diameter of the nerve conduit inner layer is 1.5-2 mm, and the thickness of the nerve conduit inner layer is 0.5-1 mm; the outer layer of the nerve conduit is a composite layer with a radial finger-shaped porous structure, which is formed by directionally freezing and casting a hydrogel cross-linked network formed by mixing potassium sodium niobate nanorods modified by polydopamine and a biopolymer material, and the thickness of the outer layer of the nerve conduit is 1-2mm. A three-dimensional weaving technology, a piezoelectric nano material and a biopolymer material are combined, a novel multifunctional nerve conduit is developed to repair nerve injury, a better solution is provided for nerve repair, and the fabric enhanced electric activity nerve conduit has important practical guiding significance in application of future clinical nerve injury repair.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, and in particular to a fabric-reinforced electrically active nerve conduit and a preparation method and application thereof. Background Art

[0002] Traumatic peripheral nerve injury is one of the common clinical diseases, and the repair of long-segment peripheral nerve injuries remains a global problem. A large number of new cases of peripheral nerve injury are reported in my country every year. The existing nerve graft repair effect is not ideal, and the loss of nerve function has a significant impact on their daily activities and careers. The repair of peripheral nerve defects requires "bridge guidance" rather than simple "patching". Artificial nerve conduits (NGCs) are an effective strategy for treating long-distance peripheral nerve injuries. Artificial nerve conduits can provide a favorable microenvironment for nerve regeneration, prevent fibroblast invasion, prevent inflammatory cell infiltration and scar formation, and guide and promote axonal growth.

[0003] However, the current use of nerve conduits to repair nerve defects faces some problems: (1) It is difficult to adapt the mechanical properties to the three-dimensional space required for nerve regeneration. The ideal nerve conduit should have appropriate strength, hardness and plasticity to create a relatively closed and stable microenvironment to ensure the smooth flow of nerve regeneration channels. The current mold-molded or 3D-printed conduits can achieve the required mechanical support strength, but it is difficult to achieve sufficient plasticity and cannot meet the flexibility requirements of free bending of nerves of different shapes. (2) It is difficult to reconstruct the blood supply of long-distance peripheral nerve grafts. Before the new blood circulation of the graft itself is established, tissue fluid infiltrates through the epineurium to supply nutrients. If the bridging material cannot obtain nutrients in time, it is not conducive to the survival of Schwann cells and the growth of regenerated axons, resulting in central necrosis of the graft and affecting nerve regeneration. (3) It is difficult for nerve fibers to regenerate over long distances and difficult to form a precise docking with the target organ. The regeneration rate of peripheral nerves is limited, so when there is a long defect, the time required for nerve regeneration is significantly extended. When the distal Schwann cells cannot contact the regenerated axons within about 8 weeks, the secretion of neurotrophic factors and cytokines will decrease. In addition, the proliferation and migration abilities of proximal nerve regeneration-related cells will gradually decline, which is not conducive to the effective regeneration of axons.

[0004] In view of this, it is necessary to design an improved fabric-reinforced electroactive nerve conduit and its preparation method and application to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides a fabric-reinforced electroactive nerve conduit and its preparation method and application, aiming to solve the technical problems of poor mechanical performance adaptation, difficult blood supply reconstruction and long nerve regeneration time of existing artificial nerve conduits.

[0006] In the first aspect, the present application provides a fabric-reinforced electroactive nerve conduit, comprising a nerve conduit inner layer and a nerve conduit outer layer, wherein the nerve conduit inner layer is a woven skeleton formed by a three-dimensional weaving process of magnesium wire as parallel yarn and degummed silk, and the pore size of the nerve conduit inner layer is 1.5 to 2 mm and the thickness is 0.5 to 1 mm; the nerve conduit outer layer is a composite layer having a radial finger-like porous structure formed by mixing polydopamine-modified potassium sodium niobate nanorods and biopolymer materials to form a hydrogel cross-linked network through directional freeze casting, and the thickness of the nerve conduit outer layer is 1 to 2 mm.

[0007] As a further improvement of the present application, the magnesium wires are evenly distributed circumferentially in four groups of two to form a conductive topological structure; the diameter of the magnesium wires is 0.05 to 0.1 mm, and the distance between the two magnesium wires in each group is 80 to 120 μm; the linear density of the degummed silk is 10 to 20D.

[0008] As a further improvement of the present application, the braiding angle of the three-dimensional braiding process is 45 to 60 degrees, and the braiding structure is one or more of a diamond braiding structure, a regular braiding structure, and a Hergless braiding structure.

[0009] As a further improvement of the present application, the biopolymer material is one or more of methacrylated hyaluronic acid, methacrylated chitosan, methacrylated gelatin, methacrylated sodium alginate, polyethylene glycol diacrylate, pluronic acrylate, and polyvinyl alcohol.

[0010] In a second aspect, the present application provides a method for preparing the fabric-reinforced electrically active nerve conduit according to the first aspect, comprising the following steps:

[0011] S1. Using magnesium filaments as parallel yarns and degummed silk as braiding yarns, a 3D braided skeleton was formed to serve as the inner layer of the nerve conduit.

[0012] S2. Mix polydopamine-modified potassium sodium niobate nanorods with biopolymer materials to prepare a hydrogel precursor solution, sleeve the inner layer of the nerve conduit on a metal rod and fix it in a mold, inject the hydrogel precursor solution onto the outer side of the inner layer of the nerve conduit, perform a cross-linking treatment, and then perform a directional freezing treatment to obtain a fabric-reinforced electroactive nerve conduit.

[0013] As a further improvement of the present application, the directional freezing treatment includes: inserting one end of the metal rod into liquid nitrogen and freezing it for 4.5 to 5.5 hours, and then placing the mold into a freeze dryer and freeze-drying it at -55 to 65°C for 24 to 48 hours to form a radial finger-shaped porous structure.

[0014] As a further improvement of the present application, the addition amount of the polydopamine-modified potassium sodium niobate nanorods is 0.5% to 5% of the mass of the biopolymer material; and the concentration of the biopolymer material is 0.01 to 0.2 g / mL.

[0015] As a further improvement of the present application, the cross-linking treatment is photoinitiator cross-linking or physical cross-linking; the photoinitiator is one or more of α-ketoglutaric acid, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, and phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt; the concentration of the photoinitiator is 0.01 to 0.05 g / mL.

[0016] As a further improvement of the present application, the preparation method of the polydopamine-modified potassium sodium niobate nanorods comprises the following steps:

[0017] KCl, K2CO3, and Nb2O5 are mixed and ground uniformly in a molar ratio of 0.4-0.6:0.02-0.03:0.04-0.06, calcined at 900-1100°C for 3-5 hours, washed, and dried to obtain a potassium sodium niobate precursor;

[0018] The potassium sodium niobate precursor is mixed with Na2CO3, NaCl, K2CO3 and KCl in a mass ratio of 1-5:3-3.5:0.2-0.4:0.3-0.4:3-3.5, and ground uniformly, calcined at 800-900°C for 5-20 minutes, washed and dried to obtain potassium sodium niobate nanorods;

[0019] The potassium sodium niobate nanorods are dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 2 to 10 mg / mL, and dopamine hydrochloride is added and mixed evenly. The mass ratio of the potassium sodium niobate nanorods to the dopamine hydrochloride is 1:(2 to 5). The pH value of the solution is adjusted to 7.5 to 8.5, and the reaction is stirred for 5 to 12 hours. After washing and centrifugation, polydopamine-modified potassium sodium niobate nanorods are obtained.

[0020] In a third aspect, the present application provides a use of the fabric-reinforced electroactive nerve conduit described in the first aspect or the fabric-reinforced electroactive nerve conduit prepared by the preparation method described in the second aspect in the preparation of nerve repair materials.

[0021] The beneficial effects of this application are:

[0022] The present application provides a fabric-reinforced electroactive nerve conduit and its preparation method and application. The fabric-reinforced electroactive nerve conduit comprises an inner nerve conduit layer and an outer nerve conduit layer. The inner nerve conduit layer comprises a braided skeleton formed by a three-dimensional weaving process using magnesium filaments as parallel yarns and degummed silk. The inner nerve conduit layer has a pore size of 1.5 to 2 mm and a thickness of 0.5 to 1 mm. The outer nerve conduit layer comprises a composite layer having a radially finger-shaped porous structure formed by directional freeze casting, formed by mixing polydopamine-modified potassium sodium niobate nanorods with biopolymer materials to form a hydrogel cross-linked network. The outer nerve conduit layer has a thickness of 1 to 2 mm. This application combines three-dimensional weaving technology, piezoelectric nanomaterials, and biopolymer materials to develop a new multifunctional nerve conduit for repairing nerve damage, providing a better solution for nerve repair. The fabric-reinforced electroactive nerve conduit has important practical guiding significance for future clinical applications in nerve damage repair.

[0023] The fabric-reinforced electroactive nerve conduit provided in this application promotes nerve regeneration through the following synergistic mechanisms: the magnesium wire conductive topology provides a conductive microenvironment that promotes the migration and growth of nerve axons; the piezoelectric hydrogel composited with polydopamine-modified potassium sodium niobate nanorods produces a piezoelectric effect under ultrasonic excitation, and electrical stimulation activates the regeneration of nerve axons; and the radially porous structure enables tissue fluid penetration and the transport of nutrients from the outside to the conduit. The potassium sodium niobate nanorods prepared in this application have a high aspect ratio, reaching 15:1. Nanorods with a high aspect ratio are more likely to deform under ultrasonic actuation, which is beneficial for improving piezoelectric performance.

[0024] The braided tubular fabric provided in this application has advantages such as biomimetic surface morphology, flexible forming methods, good mechanical properties, and elasticity. It can maintain its shape during surgical operations and resist the compression of in vivo tissue during nerve regeneration, providing ample space for nerve regeneration. Furthermore, the fiber-braided nerve conduit provided in this application has a porous structure and high permeability, which facilitates the penetration of tissue fluid into the conduit through the epineurium during the early stages of transplantation, thus providing the necessary nutritional support for nerve regeneration.

[0025] The conductive microenvironment promotes axon regeneration. Conductive scaffolds can support nerve signal conduction, facilitate communication and signal transmission between neurons, and promote nerve function recovery. In the process of peripheral nerve repair, the topological structure can provide directional signals to cells, guiding them to migrate in a specific direction, thereby promoting the growth of neurons along the direction of the topological structure, and helping to form correct neural connections. The present application combines the conductive properties and topological structure to design a nerve conduit with a conductive topological structure, and uses degradable magnesium wire conductive fibers to provide a conductive topological structure for nerve axon regeneration. By utilizing the sensitivity of neurons to conductive materials, neurons are recruited to enter the conductive topological structure for rapid migration and growth.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0028] Figure 1 This is a scanning electron micrograph of polydopamine-modified sodium potassium niobate nanorods in Example 1 of the present application;

[0029] Figure 2 This is a photo of the fabric-reinforced electroactive nerve conduit in Example 1 of the present application;

[0030] Figure 3 This is a diagram of the radial finger-shaped porous structure of the outer layer of the nerve conduit in Example 1 of the present application;

[0031] Figure 4 This is a graph showing the mechanical properties of the fabric-reinforced electroactive nerve conduit in Example 1 of the present application;

[0032] Figure 5 This is a section diagram of nerve regeneration and repair tissue in Example 8 and Comparative Examples 3-4 of the present application;

[0033] Figure 6 This is a structural diagram of the self-made mold and its components in the embodiment of this application;

[0034] Explanation of the accompanying drawings: 1. upper cover; 2. lower cover; 3. support column. DETAILED DESCRIPTION

[0035] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0037] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0038] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0039] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0040] Traumatic peripheral nerve injury is one of the most common diseases in clinical practice. Artificial nerve conduits are considered to be an effective strategy for treating long-distance peripheral nerve injury, but they still face problems such as the difficulty in adapting mechanical properties to the three-dimensional space required for nerve regeneration, difficulty in revascularizing long-distance peripheral nerve grafts, and difficulty in regenerating nerve fibers across long distances.

[0041] In order to solve the technical problems of artificial nerve conduits in which the mechanical properties do not match the requirements of nerve regeneration, blood supply reconstruction is difficult, and the nerve regeneration efficiency is low, the present application provides a fabric-reinforced electroactive nerve conduit and its preparation method and application. Specifically, by combining three-dimensional weaving technology, piezoelectric nanomaterials and biopolymer materials, a new multifunctional nerve conduit is developed to repair nerve damage, providing a better solution for nerve repair.

[0042] In a first aspect, an embodiment of the present application provides a fabric-reinforced electroactive nerve conduit, comprising a nerve conduit inner layer and a nerve conduit outer layer, wherein the inner layer of the nerve conduit is a woven skeleton formed by a three-dimensional weaving process of magnesium wire as parallel yarn and degummed silk, the pore size of the inner layer of the nerve conduit is 1.5 to 2 mm, and the thickness is 0.5 to 1 mm; the outer layer of the nerve conduit is a composite layer having a radial finger-like porous structure formed by mixing polydopamine-modified potassium sodium niobate nanorods and biopolymer materials to form a hydrogel cross-linked network through directional freeze casting, and the thickness of the outer layer of the nerve conduit is 1 to 2 mm.

[0043] In the technical solution of the embodiment of the present application, the nerve conduit is composed of an inner braided skeleton and an outer piezoelectric hydrogel composite structure. The braided skeleton formed by the three-dimensional weaving process of magnesium wire and degummed silk not only provides sufficient mechanical strength, but also gives the conduit good flexibility, so that it can adapt to the free bending requirements of nerves of different shapes, thereby solving the problem that the mechanical properties of existing nerve conduits are difficult to adapt to the three-dimensional space required for nerve regeneration. The pore size and thickness design of the braided skeleton ensure that the conduit does not cause excessive physical obstruction to nerve regeneration while providing the necessary mechanical support. The radial finger-like porous structure of the outer layer of the nerve conduit helps to promote the penetration and growth of new blood vessels, improves the nutrient supply problem of the transplant before the establishment of new blood circulation, and thus avoids the risk of central necrosis. The hydrogel cross-linked network formed by polydopamine-modified potassium sodium niobate nanorods (KNN@PDA) and biopolymer materials has good biocompatibility and can also release pro-angiogenic factors through a sustained-release mechanism to further promote blood supply reconstruction. As an electroactive material, potassium sodium niobate nanorods can promote the activation of Schwann cells and the secretion of neurotrophic factors through the piezoelectric effect, thereby accelerating axonal growth and nerve regeneration. The woven skeleton and the hydrogel cross-linked network jointly construct a microenvironment that is conducive to nerve regeneration, preventing the invasion of fibroblasts and the infiltration of inflammatory cells, reducing scar formation, and ensuring the smooth flow of nerve regeneration channels. The radial finger-like porous structure formed by the directional freeze-casting technology in this application not only contributes to angiogenesis, but also guides the directional growth of nerve fibers, thereby increasing the possibility of precise docking of nerve regeneration with target organs.

[0044] Furthermore, in some embodiments, the magnesium wires are evenly distributed circumferentially in four groups of two to form a conductive topological structure; the diameter of the magnesium wires is 0.05-0.1 mm, and the distance between the two magnesium wires in each group is 80-120 μm; the linear density of the degummed silk is 10-20D.

[0045] In the technical solution of the embodiment of the present application, the inner skeleton is formed by a three-dimensional weaving process with 8 magnesium wires as the axial yarn and degummed silk. The magnesium wires are evenly distributed circumferentially in four groups of two, forming a specific conductive topological structure, which enhances the conductivity of the catheter. It can also promote the directional growth of nerve cells and the conduction of electrical signals through a specific electric field distribution. The circumferential uniform distribution enhances the overall mechanical properties of the catheter, so that it can provide uniform support and flexibility in all directions, and better adapt to nerve defects of different shapes and sizes. Appropriate spacing and diameter can avoid excessive compression of nerve cells while providing necessary electrical stimulation. The linear density of the degummed silk ensures the flexibility and biocompatibility of the braided skeleton, while providing sufficient mechanical strength to prevent excessive deformation or rupture of the catheter.

[0046] Furthermore, in some embodiments, the braiding angle of the three-dimensional braiding process is 45 to 60 degrees, and the braiding structure is one or more of a diamond braiding structure, a regular braiding structure, and a Hergless braiding structure.

[0047] In the technical solutions of the embodiments of this application, a suitable braiding angle helps optimize the stress distribution of the braided skeleton, enabling it to provide uniform mechanical support in all directions. The specific braiding structure can provide better structural stability, preventing deformation or collapse of the braided skeleton after implantation, and ensuring the long-term unobstructed flow of nerve regeneration pathways.

[0048] Furthermore, in some embodiments, the biopolymer material is one or more of methacrylated hyaluronic acid (HAMA), methacrylated chitosan (CSMA), methacrylated gelatin (GelMA), methacrylated sodium alginate (AlgMA), polyethylene glycol diacrylate (PEGDA), pluronic acrylate (F127DA), and polyvinyl alcohol (PVA).

[0049] In the technical solutions of the embodiments of this application, the biopolymer material is a cross-linked biopolymer material. By adding a photoinitiator for cross-linking or physical cross-linking, it forms a hydrogel cross-linked network, which provides a matrix for cell attachment and growth, promoting the attachment, proliferation, and differentiation of nerve cells and Schwann cells, thereby accelerating the nerve regeneration process. By selecting different biopolymer materials and adjusting their proportions, the mechanical properties of the hydrogel can be adjusted to better match the mechanical properties of neural tissue, providing appropriate support and protection.

[0050] In a second aspect, an embodiment of the present application provides a method for preparing a fabric-reinforced electrically active nerve conduit, comprising the following steps:

[0051] S1. Using magnesium filaments as parallel yarns and degummed silk as braiding yarns, a 3D braided skeleton was formed to serve as the inner layer of the nerve conduit.

[0052] S2. Mix polydopamine-modified potassium sodium niobate nanorods with biopolymer materials to prepare a hydrogel precursor solution. The inner layer of the nerve conduit is placed on a metal rod and fixed in a mold. The hydrogel precursor solution is injected onto the outer side of the inner layer of the nerve conduit. After cross-linking treatment, a directional freezing treatment is performed to obtain a fabric-reinforced electroactive nerve conduit.

[0053] In the technical solution of the embodiment of the present application, the inner skeleton formed by the three-dimensional weaving process provides excellent mechanical strength and flexibility, can withstand the complex mechanical environment in the body, and adapt to the bending and stretching of nerves. Polydopamine-modified potassium sodium niobate nanorods have good biocompatibility and bioactivity, and can promote the adhesion, proliferation and differentiation of nerve cells. The hydrogel network formed by biopolymer materials provides a matrix for cell growth, which contributes to the directional growth and angiogenesis of nerve fibers. The radial finger-like porous structure formed by the directional freeze-casting technology not only contributes to the transmission of nutrients, but also guides the directional growth of nerve fibers, thereby increasing the possibility of precise docking between nerve regeneration and target organs. This method realizes the preparation of complex structures through simple steps and is suitable for large-scale production and clinical applications.

[0054] Furthermore, in some embodiments, the directional freezing treatment includes: inserting one end of the metal rod into liquid nitrogen and freezing it for 4.5 to 5.5 hours, and then placing the mold into a freeze dryer at -55 to 65°C and freeze-drying it for 24 to 48 hours to form a radial finger-shaped porous structure.

[0055] In the technical solution of the present embodiment, a custom mold is used for directional freezing. The inner layer of the nerve conduit skeleton is placed over a metal rod and secured in the mold. A hydrogel precursor solution is then poured into the mold. The metal rod at one end of the mold is then plunged into liquid nitrogen for freezing, forming a radially oriented ice crystal structure. The material is then freeze-dried in a freeze dryer to form the outer layer of the nerve conduit with a directional, finger-like porous structure. During the liquid nitrogen freezing process, water in the hydrogel rapidly forms ice crystals. Due to the directional growth characteristics of the ice crystals, a finger-like structure with a specific orientation is formed. During the freeze-drying stage, the ice crystals directly sublime into water vapor, leaving behind a porous structure. These pores are radially distributed in a finger-like pattern, providing an ideal microenvironment for cell attachment, migration, and nerve regeneration. Specifically, the liquid nitrogen temperature of approximately -196°C rapidly freezes the material, forming a uniform ice crystal structure. This ice crystal structure forms the foundation for the subsequent porous structure. The liquid nitrogen freezing time is sufficient to form a uniform ice crystal structure while avoiding damage to the material caused by overfreezing. The freeze-drying temperature and time ensure complete water removal while preserving the porous structure.

[0056] Furthermore, in some embodiments, the amount of polydopamine-modified potassium sodium niobate nanorods added is 0.5-5% of the mass of the biopolymer material; and the concentration of the biopolymer material is 0.01-0.2 g / mL.

[0057] In the technical solution of the embodiment of the present application, polydopamine-modified potassium sodium niobate nanorods are added to the biopolymer material in a predetermined proportion to form a uniformly dispersed hydrogel precursor solution. The polydopamine-modified potassium sodium niobate nanorods have excellent piezoelectric properties and can generate electrical signals under the action of external force, thereby promoting the electrophysiological activity of nerve cells. The concentration of the biopolymer material in the hydrogel precursor solution is 0.01-0.2 g / mL. The appropriate concentration of the biopolymer material can form a stable and uniform hydrogel cross-linked network, providing good mechanical properties and structural stability for the nerve conduit. The addition amount of polydopamine-modified potassium sodium niobate nanorods exceeds 5% of the mass of the biopolymer material. Although it can further increase the mechanical properties of the nerve conduit, it can cause cytotoxicity. Due to the inherent nano-effect of nanomaterials, excessive nanomaterials are taken up by cells and cause certain cytotoxicity. Therefore, the addition amount of polydopamine-modified potassium sodium niobate nanorods is 0.5-5% of the mass of the biopolymer material. It can balance the piezoelectric properties and biocompatibility of the nerve conduit, and obtain a nerve conduit with excellent comprehensive performance.

[0058] Furthermore, in some embodiments, the crosslinking treatment is photoinitiator crosslinking or physical crosslinking; the photoinitiator is one or more of α-ketoglutaric acid, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, and phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt; the concentration of the photoinitiator is 0.01 to 0.05 g / mL.

[0059] In the technical solution of the embodiment of the present application, the hydrogel precursor solution can be cross-linked by photoinitiator by selecting a suitable photoinitiator, or cross-linked by freeze-thaw method to form a stable and uniform hydrogel cross-linked network, thereby improving the mechanical strength, toughness and tensile strength of the hydrogel. At the same time, the cross-linked hydrogel can provide a better cell adhesion matrix, promote the adhesion, proliferation, differentiation and directional growth of nerve cells, thereby accelerating nerve regeneration and functional recovery. The concentration of the photoinitiator directly affects the number of active species produced, thereby affecting the density of cross-linking points. The higher the concentration of the photoinitiator, the faster the polymerization reaction rate, but too high a concentration may cause uneven cross-linking or generate excessive heat, affecting the performance of the material.

[0060] Furthermore, in some embodiments, the preparation method of polydopamine-modified potassium sodium niobate nanorods comprises the following steps:

[0061] S21. KCl, K2CO3, and Nb2O5 are mixed in a molar ratio of 0.4-0.6:0.02-0.03:0.04-0.06, ground uniformly with ethanol, and calcined at 900-1100°C for 3-5 hours. The KCl is washed off with hot deionized water, and the mixture is titrated with silver nitrate until no white precipitate is present. The nitric acid is washed off with hot deionized water until the pH reaches 7-7.5, and the mixture is oven-dried to obtain a potassium sodium niobate precursor.

[0062] S22. A potassium sodium niobate precursor is mixed with Na2CO3, NaCl, K2CO3, and KCl in a mass ratio of 1-5:3-3.5:0.2-0.4:0.3-0.4:3-3.5, ground uniformly with ethanol, calcined at 800-900°C for 5-20 min, immersed in a 10-12 mol / L hydrochloric acid solution with stirring for 4-5 h, centrifuged, and dried; and filtered with hot deionized water 3-5 times to remove NaCl and KCl to obtain potassium sodium niobate (KNN) nanorods;

[0063] S23. Disperse potassium sodium niobate nanorods in anhydrous ethanol to prepare a dispersion with a concentration of 2 to 10 mg / mL, add dopamine hydrochloride and mix evenly, the mass ratio of potassium sodium niobate nanorods to dopamine hydrochloride is 1:(2 to 5), add sodium hydroxide solution to adjust the pH value of the solution to 7.5 to 8.5, mix evenly, and stir the mixture at room temperature for 5 to 12 hours. After washing and centrifugation, polydopamine-modified potassium sodium niobate nanorods are obtained.

[0064] In the technical solutions of the present application, polydopamine (PDA) exhibits excellent biocompatibility and adhesion, improving the compatibility of KNN nanorods with biological tissues and facilitating their biomedical applications. PDA modification can also enhance the dispersibility of KNN nanorods in aqueous solutions, facilitating their application in various biological environments.

[0065] In a third aspect, embodiments of the present application provide a use of the fabric-reinforced electroactive nerve conduit described in the first aspect or the fabric-reinforced electroactive nerve conduit prepared by the preparation method described in the second aspect in the preparation of nerve repair materials.

[0066] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0067] Example 1

[0068] This embodiment provides a method for preparing a fabric-reinforced electrically active nerve conduit, comprising the following steps:

[0069] S1. Preparation of a braided framework for the inner layer of a nerve conduit: A three-dimensional braiding process was used to form a braided framework, serving as the inner layer of the nerve conduit, using magnesium filaments as parallel yarns and degummed silk as braiding yarns. The braided yarns consisted of two strands of degummed silk, each strand having a fineness of 15D. To improve the dimensional stability and mechanical properties of the nerve conduit, a three-way braided structure was used with a core braid. The silicone core maintained a constant inner diameter for easier molding. Eight magnesium wires were added along the braiding direction in a vertical spindle braiding machine (16 spindles), with four groups of two magnesium wires in total. The spacing between the two magnesium wires in each group was 100 μm, and the four groups of magnesium wires were evenly distributed around the conduit framework. The diameter of the magnesium wires was 0.08 mm.

[0070] S2. Preparation of polydopamine-modified potassium sodium niobate nanorods: Mix 0.5 mol KCl, 0.025 mol K2CO3, and 0.05 mol Nb2O5, grind with ethanol for 30 min until uniformly mixed, dry, and calcine at 1000°C for 3 h; wash away the KCl with hot deionized water, check with silver nitrate titration, and wash until there is no white precipitate; wash away the nitric acid with hot deionized water until the pH is 7, and dry in an oven to obtain a KNN precursor.

[0071] 1 g of KNN precursor, 3.35 g of Na2CO3, 0.3 g of NaCl, 0.34 g of K2CO3, and 3.35 g of KCl were mixed and ground with ethanol for 2 h. The mixture was calcined at 850°C for 10 min at a heating rate of 5°C / min. The mixture was soaked and stirred in 10 mol / L hydrochloric acid for 4 h, centrifuged, and dried. The mixture was filtered three times with hot deionized water to remove NaCl and KCl to obtain KNN.

[0072] Preparation of polydopamine-modified potassium sodium niobate nanorods: KNN was dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 5 mg / mL, dopamine hydrochloride was added and mixed evenly, the mass ratio of KNN to dopamine hydrochloride was 1:3, sodium hydroxide solution was added to adjust the pH value to 7.5, mixed evenly and stirred at room temperature for 5 hours, then the reaction solution was washed and centrifuged, and the precipitate was collected to obtain polydopamine-modified potassium sodium niobate. The scanning electron microscopy image of polydopamine-modified potassium sodium niobate nanorods is shown below. Figure 1 shown.

[0073] Preparation of fabric-reinforced electrically active nerve conduits: Fabric-reinforced electrically active nerve conduits were prepared using homemade molds, such as Figure 6As shown, the mold comprises an upper cover 1, a lower cover 2, and a central support column 3. The upper and lower covers 1 and 2 have identical structures and dimensions, with a central circular hole through which the ends of the fabric-covered metal rod can pass. The support column 3 is a hollow structure made of transparent material, with an inner diameter larger than the circular holes in the upper and lower covers 1 and 2. The polydopamine-modified potassium sodium niobate nanorods were mixed with PVA, and the addition amount of the polydopamine-modified potassium sodium niobate nanorods was 2.5% of the mass of the biopolymer material. A hydrogel precursor solution was prepared, and the concentration of PVA was 0.1 g / mL. The inner braided skeleton of the nerve conduit prepared in Example 1 was put on a metal rod with a diameter of 2 mm and fixed together in a mold. The hydrogel precursor solution was then poured into the mold and cross-linked by the freeze-thaw method to form a stable and uniform hydrogel cross-linked network. The freezing temperature was -80°C, the thawing temperature was 25°C, and the number of cycles was 3. Thereafter, the metal rod at one end of the mold was inserted into liquid nitrogen and frozen for 5 hours to form a radial ice crystal structure. The rod was then placed in a freeze dryer and freeze-dried at -55°C for 24 hours and then taken out to obtain a nerve conduit with a directional finger-like porous structure. The actual picture of the nerve conduit observed under an optical microscope is shown in the following figure. Figure 2 As shown in the figure, it can be seen that the outer wall of the catheter is smooth, the inner layer is made of fabric, and the middle part is a tubular lumen structure. Figure 3 As shown in Figure 2, electron microscope photography shows that the outer wall of the catheter presents a finger-like directional pore structure. Figure 4 As shown, the mechanical strength of the freeze-dried hydrogel is not high, and the mechanical strength of the double-layer catheter after being composited with degummed silk fabric is significantly improved.

[0074] Example 2

[0075] This embodiment provides a method for preparing a fabric-reinforced electrically active nerve conduit. Compared with Example 1, the only difference is that the diameter of the magnesium wire is 0.05 mm.

[0076] Example 3

[0077] This embodiment provides a method for preparing a fabric-reinforced electrically active nerve conduit. Compared with Example 1, the only difference is that the diameter of the magnesium wire is 0.1 mm.

[0078] Example 4

[0079] This embodiment provides a method for preparing a fabric-reinforced electrically active nerve conduit. Compared with Example 1, the only difference is that the amount of polydopamine-modified potassium sodium niobate nanorods added is 0.5% of the mass of PVA.

[0080] Example 5

[0081] This embodiment provides a method for preparing a fabric-reinforced electrically active nerve conduit. Compared with Example 1, the only difference is that the amount of polydopamine-modified potassium sodium niobate nanorods added is 5% of the mass of PVA.

[0082] Example 6

[0083] This embodiment provides a method for preparing a fabric-reinforced electroactive nerve conduit. Compared with Example 1, the only difference is that the biopolymer material is F127DA, the cross-linking treatment is photoinitiator cross-linking, the photoinitiator is α-ketoglutaric acid with a concentration of 0.02 g / mL, a 405 nm ultraviolet light source is used, and the illumination time is 1 min.

[0084] Example 7

[0085] This embodiment provides a method for preparing a fabric-reinforced electrically active nerve conduit. Compared with Example 6, the only difference is that the biopolymer material is PEGDA.

[0086] Comparative Example 1

[0087] Comparative Example 1 provides a method for preparing a fabric-reinforced electroactive nerve conduit. Compared with Example 1, the only difference is that polydopamine-modified potassium sodium niobate nanorods are not added.

[0088] Comparative Example 2

[0089] Comparative Example 2 provides a method for preparing a fabric-reinforced electrically active nerve conduit. Compared with Example 1, the only difference is that magnesium wire is not used in the inner braided skeleton of the nerve conduit.

[0090] The performance test results of the fabric-reinforced electroactive nerve conduits prepared in various examples and comparative examples are shown in Table 1.

[0091] Table 1 Performance test results

[0092]

[0093]

[0094] As can be seen from Table 1, increasing the amount of potassium sodium niobate nanorods added improves the piezoelectric properties of the nerve conduit. Although the mechanical properties are reduced, they still meet the requirements of use. The type of biopolymer material also has a certain impact on the mechanical properties of the nerve conduit. The gel strength of the biopolymer material in Examples 6-7 is weaker than that of the PVA in Example 1, resulting in a decrease in mechanical properties, but it still meets the requirements of use.

[0095] Example 8

[0096] This embodiment provides a method for treating peripheral nerve damage by nerve conduit implantation, using the fabric-reinforced electrically active nerve conduit prepared in Example 1, and specifically comprising the following steps:

[0097] S1. Construction of a sciatic nerve injury model: Healthy 250g Sprague-Dawley rats were anesthetized with an intraperitoneal injection of 3% sodium pentobarbital. The rats were secured to the operating table, and the skin of the right thigh was shaved and disinfected with iodine. An incision was made in the posterior midline depression, and the skin was opened. A surgical incision of approximately 1.5 cm was made. The right sciatic nerve was carefully dissected along the intermuscular space to expose the nerve. The nerve was fixed at both ends and the midsection was resected, creating a 12mm nerve defect.

[0098] S2. Sciatic nerve repair surgery: A 14mm nerve conduit was implanted to connect the distal and proximal ends of the nerve. The nerve stumps on both sides were inserted approximately 1mm into the conduit, leaving 1mm of suture at each end. The joint was closed with 8-0 surgical suture. In the autologous group, the excised sciatic nerve was sutured in situ at an angle of 180°. The incision was closed layer by layer, with 5-0 surgical suture for muscle sutures and 3-0 surgical suture for epidermal sutures. Ultrasound stimulation was applied to the nerve conduit implantation site for 20 minutes daily for 2 weeks.

[0099] S3. Postoperative Functional Assessment: Gait analysis was performed 8 weeks after surgery. The rat's hind limbs were dipped in red ink and guided to walk autonomously within a 10 cm × 40 cm wooden passage covered with white paper. Two valid gait trajectories were recorded. The animals were then sacrificed, and the gastrocnemius muscles on both sides were completely dissected. After rinsing with saline and drying, the surface moisture was blotted out. The wet weights of the muscles on the surgical and uninjured sides were accurately weighed, and the ratio was calculated. The gross morphology of the regenerated sciatic nerve was recorded using microphotography.

[0100] S4. Histological and Morphological Analysis: Gastrocnemius muscle specimens from the normal, autologous, conduit, and defect groups were fixed with 4% paraformaldehyde for 24 hours and then embedded in paraffin. Sections were stained with Masson's trichrome, and six randomly selected fields at 100x magnification were examined under a light microscope. Image J software was used to quantitatively analyze the percentage of muscle fiber area, and the average diameter of 100 muscle fibers was measured. Regenerated nerve specimens were fixed with 2.5% glutaraldehyde at 4°C for 24 hours, embedded in epoxy resin, and ultrathin sections were prepared. After double staining with lead citrate and uranyl acetate, myelin sheath thickness and axon diameter were observed by transmission electron microscopy. Image J software was used to quantitatively analyze the number of regenerated nerve fibers and morphological parameters (experimental group: MSF / PVA@KNN+US).

[0101] Comparative Example 3

[0102] Comparative Example 3 provides a method for treating peripheral nerve injury by nerve conduit transplantation. Compared with Example 8, the only difference is that the nerve conduit used is the nerve conduit without magnesium wire prepared in Comparative Example 2 (experimental grouping: SF / PVA@KNN).

[0103] Comparative Example 4

[0104] Comparative Example 4 provides a method for treating peripheral nerve injury by nerve conduit implantation. Compared with Example 8, the only difference is that no ultrasonic excitation stimulation is performed (experimental grouping: MSF / PVA@KNN).

[0105] like Figure 5 As shown in the results, 3 months after the composite scaffold was implanted in the sciatic nerve defect of rats, the regenerated nerve site was sectioned and stained with H&E. The regenerated nerve effect was more obvious after the ultrasound-excited piezoelectric nerve conduit was implanted, and the nerve tissue repair status was better than that of SF / PVA@KNN and MSF / PVA@KNN, and was comparable to that of the autologous nerve transplantation group.

[0106] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A fabric-reinforced electrically active nerve conduit, characterized in that: The invention comprises an inner layer of a nerve conduit and an outer layer of a nerve conduit. The inner layer of the nerve conduit is a woven skeleton formed by a three-dimensional weaving process of magnesium wire as parallel yarn and degummed silk. The pore size of the inner layer of the nerve conduit is 1.5 to 2 mm and the thickness is 0.5 to 1 mm. The outer layer of the nerve conduit is a composite layer with a radial finger-shaped porous structure formed by directional freeze casting by mixing polydopamine-modified potassium sodium niobate nanorods and biopolymer materials to form a hydrogel cross-linked network. The thickness of the outer layer of the nerve conduit is 1 to 2 mm.

2. The fabric-reinforced electrically active nerve conduit according to claim 1, characterized in that: The magnesium wires are evenly distributed circumferentially in four groups of two to form a conductive topological structure; the diameter of the magnesium wires is 0.05-0.1 mm, and the distance between the two magnesium wires in each group is 80-120 μm; the linear density of the degummed silk is 10-20D.

3. The fabric-reinforced electrically active nerve conduit according to claim 1, characterized in that: The braiding angle of the three-dimensional braiding process is 45 to 60 degrees, and the braiding structure is one or more of a diamond braiding structure, a regular braiding structure, and a Hergless braiding structure.

4. The fabric-reinforced electrically active nerve conduit according to claim 1, wherein: The biopolymer material is one or more of methacrylated hyaluronic acid, methacrylated chitosan, methacrylated gelatin, methacrylated sodium alginate, polyethylene glycol diacrylate, pluronic acrylate, and polyvinyl alcohol.

5. A method for preparing a fabric-reinforced electrically active nerve conduit according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Using magnesium filaments as parallel yarns and degummed silk as braiding yarns, a 3D braided skeleton was formed to serve as the inner layer of the nerve conduit. S2. Mix polydopamine-modified potassium sodium niobate nanorods with biopolymer materials to prepare a hydrogel precursor solution, sleeve the inner layer of the nerve conduit on a metal rod and fix it in a mold, inject the hydrogel precursor solution onto the outer side of the inner layer of the nerve conduit, perform a cross-linking treatment, and then perform a directional freezing treatment to obtain a fabric-reinforced electroactive nerve conduit.

6. The method for preparing a fabric-reinforced electrically active nerve conduit according to claim 5, characterized in that: The directional freezing treatment includes: inserting one end of the metal rod into liquid nitrogen and freezing for 4.5 to 5.5 hours, and then placing the mold into a freeze dryer at -55 to 65° C. and freeze drying for 24 to 48 hours to form a radial finger-shaped porous structure.

7. The method for preparing a fabric-reinforced electrically active nerve conduit according to claim 5, characterized in that: The addition amount of the polydopamine-modified potassium sodium niobate nanorods is 0.5-5% of the mass of the biopolymer material; and the concentration of the biopolymer material is 0.01-0.2 g / mL.

8. The method for preparing a fabric-reinforced electrically active nerve conduit according to claim 7, characterized in that: The crosslinking treatment is photoinitiator crosslinking or physical crosslinking; the photoinitiator is one or more of α-ketoglutaric acid, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, and phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt; the concentration of the photoinitiator is 0.01 to 0.05 g / mL.

9. The method for preparing a fabric-reinforced electrically active nerve conduit according to claim 5, characterized in that: The preparation method of the polydopamine-modified potassium sodium niobate nanorods comprises the following steps: KCl, K2CO3, and Nb2O5 are mixed and ground uniformly in a molar ratio of 0.4-0.6:0.02-0.03:0.04-0.06, calcined at 900-1100°C for 3-5 hours, washed, and dried to obtain a potassium sodium niobate precursor; The potassium sodium niobate precursor is mixed with Na2CO3, NaCl, K2CO3 and KCl in a mass ratio of 1-5:3-3.5:0.2-0.4:0.3-0.4:3-3.5, and ground uniformly, calcined at 800-900°C for 5-20 minutes, washed and dried to obtain potassium sodium niobate nanorods; The potassium sodium niobate nanorods are dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 2 to 10 mg / mL, and dopamine hydrochloride is added and mixed evenly. The mass ratio of the potassium sodium niobate nanorods to the dopamine hydrochloride is 1:(2 to 5). The pH value of the solution is adjusted to 7.5 to 8.5, and the reaction is stirred for 5 to 12 hours. After washing and centrifugation, polydopamine-modified potassium sodium niobate nanorods are obtained.

10. Use of the fabric-reinforced electrically active nerve conduit according to any one of claims 1 to 4 or the fabric-reinforced electrically active nerve conduit prepared by the preparation method according to any one of claims 5 to 9 in the preparation of nerve repair materials.

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