Nerve conduit with composite conductive ink modified coating and methods of making and use

Abstract

The present application relates to a nerve conduit with a composite conductive ink modified coating, the nerve conduit comprising a nerve conduit body, and a dopamine coating and a conductive coating provided on the nerve conduit body, the conductive coating being a conductive coating prepared by coating and drying of a PEDOT:PSS solution with carbon nanotubes added.The present application also provides a preparation method and application of the nerve conduit.The nerve conduit of the present application is modified by CNT / PEDOT composite conductive ink, which not only improves the conductivity of the conduit material and accelerates the conduction of nerve electrical signals, but also promotes the adhesion, orientation and growth of nerve cells on the surface of the conduit, is conducive to promoting the alignment healing of the damaged nerve stumps, and has a hardness matching the interface of the nerve tissue; at the same time, the preparation method of the present application is simple and easy to operate, low in cost, and convenient for industrialized production and clinical application.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to a nerve conduit with a composite conductive ink-modified coating, as well as the method for preparing the nerve conduit and its applications. Background Technology

[0002] Peripheral nerve injury is a common condition that leads to varying degrees of sensory and motor dysfunction, including paresthesia at the site of injury, intractable neuralgia, or denervation paralysis of the limbs, placing a significant burden on patients and society. Currently, the gold standard for treating nerve injuries longer than 2mm is autologous nerve transplantation. However, this method has drawbacks such as donor nerve shortage, size mismatch between donor and recipient nerves, donor site damage, and time-consuming secondary surgeries. Therefore, the use of artificial nerve conduits has become the most likely alternative to autologous nerve transplantation for repair.

[0003] Given the complex electrophysiological environment of peripheral nerves, biomimetic construction of bioelectric fields to simulate natural nerve electrophysiological characteristics and regulate nerve cell behavior has gradually become a hot topic in peripheral nerve repair research. When nerve cells are exposed to an electric field, one side of the cell becomes hyperpolarized while the other side depolarizes. When this potential difference across the nerve cell membrane reaches a threshold, it leads to the formation of action potentials, thereby promoting nerve cell survival, migration, and axonal elongation. Increasing research shows that the introduction of electroactive materials can modulate nerve cell behavior by altering the bioelectric field to transmit biochemical signals and activate signaling pathways related to nerve regeneration, thus promoting the healing of injured peripheral nerves. Simultaneously, electroactive materials can also connect damaged nerves in the form of scaffolds, providing mechanical support, and provide physical guidance cues for regenerating nerves through the design of surface microtopomorphology.

[0004] Melted near-field direct writing (MEW) is an emerging 3D printing technology that uses accelerated voltage-stabilized polymer melt jets to directly write pre-designed submicron fiber patterns into a collector. MEW creates precisely aligned and oriented fiber structures that can guide nerve cells. We previously used MEW to fabricate a polycaprolactone (PCL) nerve conduit with ring and strip structures and demonstrated its effectiveness in regulating the directional alignment of nerve cells. Building on this, integrating electroactive functions into MEW nerve conduits has been shown to aid in the repair of peripheral nerve injuries in vivo and abroad. However, electroactive materials often suffer from significant drawbacks, such as difficulty in functionalization, lack of biodegradability, poor solubility and processability, and insufficient mechanical properties, preventing their direct application as substrates for MEW.

[0005] Therefore, there is a need to find a nerve conduit that simultaneously possesses low impedance, high charge transfer capability, good conductivity stability, and can match the stiffness of the nerve tissue interface, as well as its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a nerve conduit with low impedance, high charge transfer capability, good conductivity stability, and the ability to match the interface stiffness of nerve tissue. This invention also provides a method for preparing the nerve conduit and its applications.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] A nerve conduit with a composite conductive ink-modified coating, the nerve conduit comprising a nerve conduit body, and a dopamine coating and a conductive coating disposed on the nerve conduit body, the conductive coating being a conductive coating obtained by coating and drying a PEDOT:PSS solution containing carbon nanotubes.

[0009] In a further preferred embodiment of the present invention, the conductive coating is further provided with a crosslinking agent layer.

[0010] In this invention, a further preferred embodiment is that the conductive coating has at least two layers.

[0011] In a further preferred embodiment of the present invention, the nerve conduit body includes a guiding structure and a supporting structure; the guiding structure includes multiple guiding fibers arranged along the axial direction of the conduit; the supporting structure includes multiple spaced supporting ring ribs; each guiding rib is spaced around the circumference of the supporting ring rib and connected to each supporting ring rib, and each supporting ring rib and each guiding rib integrally form the nerve conduit.

[0012] The method for preparing the nerve conduit with a composite conductive ink-modified coating according to the present invention includes the following steps:

[0013] S1. Preparation of dopamine coating: Take the nerve conduit body, immerse it in dopamine hydrochloride buffer solution for 8-24 hours, then wash it with deionized water and vacuum dry it to obtain dopamine coating.

[0014] S2. Preparation of conductive coating: The nerve conduit body treated in step S1 is immersed in a PEDOT:PSS solution containing carbon nanotubes for 8-15 minutes, and then dried under vacuum to obtain a conductive coating.

[0015] In this invention, a further preferred embodiment is that the dopamine hydrochloride buffer solution in step S1 has a dopamine concentration of 2 mg / mL and a pH value of 8.5.

[0016] In a further preferred embodiment of the present invention, the PEDOT:PSS solution with added carbon nanotubes in step S2 is prepared by the following steps: 2,4-ethylenedioxythiophene:polystyrene sulfonic acid solution is dissolved in deionized water and stirred evenly to obtain a dispersion solution; then carbon nanotubes are added to the dispersion solution and stirred again to disperse the carbon nanotubes evenly to obtain a carbon nanotube solution; the carbon nanotube solution is ultrasonically treated in an ultrasonic machine and then centrifuged in a centrifuge to separate the undispersed carbon nanotubes, thus obtaining the PEDOT:PSS solution with added carbon nanotubes.

[0017] In this invention, a further preferred embodiment is that the mass concentration of PEDOT:PSS in the dispersion solution is 0.2-20 mg / mL; and the mass concentration of carbon nanotubes in the PEDOT:PSS solution with added carbon nanotubes is 2 mg / mL.

[0018] In a further preferred embodiment of the present invention, step S3 is included after step S2: preparation of the crosslinking agent layer: the nerve conduit body treated in step S2 is immersed in the crosslinking agent for 1-4 minutes and dried to obtain the crosslinking agent layer; the crosslinking agent is a silane coupling agent alcohol solution.

[0019] The nerve conduit described in this invention can be used in medical devices and other products.

[0020] Compared with the prior art, the present invention has the following advantages: The nerve conduit of the present invention has a composite conductive ink modified coating (i.e., conductive coating) on ​​the nerve conduit body. The conductive coating is prepared by coating and drying a PEDOT:PSS solution with added carbon nanotubes. This can greatly reduce the impedance of the scaffold material, improve the charge transfer capability, promote biochemical signal transmission and activate signal pathways related to nerve regeneration by changing the bioelectric field, thereby regulating nerve cell behavior and promoting the healing of peripheral nerves after injury. At the same time, it overcomes the prominent problems faced by using electroactive materials alone, such as functionalization difficulties, lack of biodegradability, poor solubility and processability, and insufficient mechanical properties.

[0021] Furthermore, compared to the traditional method of using cellulose as the dispersant for CNTs, the CNT / PEDOT composite bio-conductive ink of the present invention uses PEDOT:PSS solution as the dispersant for CNTs, which not only further enhances the conductivity of the coating, but also improves the stability of the conductive coating and makes the coating exhibit a hardness that is more compatible with the nerve tissue interface.

[0022] In addition, the modification with a conductive coating further improves the hydrophilicity and cell compatibility of the PCL catheter scaffold surface, which is conducive to the attachment, spreading and growth of nerve cells on the catheter surface, thereby promoting the regeneration of damaged peripheral nerves. At the same time, it can also generate directional currents in the same direction as the topological microstructure of the catheter surface, which enhances the guiding effect on the directional arrangement of nerve cells, thereby promoting the regeneration of peripheral nerves after injury.

[0023] The preparation method of this invention is simple and environmentally friendly, with low technical threshold, strong operability, non-toxic preparation process, and low economic cost, making it suitable for industrial production. The nerve conduit of this invention has a wide range of applications due to its excellent performance, such as in medical devices (for the preparation of medical device products), laboratory supplies, and other products.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0025] Figure 1 This is a photograph of a nerve conduit with a composite conductive ink-modified coating according to Embodiment 1 of the present invention.

[0026] Figure 2 This is an image of a transverse section of mouse regenerated nerve tissue from Experiment Example 1 of the present invention, stained with TB, under a 10x microscope.

[0027] Figure 3 This is an image of a transverse section of mouse regenerated nerve tissue from Experiment Example 1 of this invention, stained with TB, under a 40x microscope.

[0028] Figure 4 This is an image of a longitudinal section of mouse regenerated nerve tissue from Experiment Example 1 of the present invention, stained with hematoxylin and eosin (HE), under a 10x microscope.

[0029] Figure 5 This is an image of a longitudinal section of mouse regenerated nerve tissue from Experiment Example 1 of the present invention, stained with hematoxylin and eosin (HE), under a 40x microscope. Detailed Implementation

[0030] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Unless otherwise specified, the equipment and reagents used in the embodiments and experimental examples in the specific embodiments are all obtained from commercial sources. The specific embodiments are exemplary and are only used to explain this application, and should not be construed as limiting the scope of protection of this application.

[0031] A nerve conduit with a composite conductive ink-modified coating, the nerve conduit comprising a nerve conduit body and a dopamine coating and a conductive coating disposed on the nerve conduit body, the conductive coating being a conductive coating obtained by coating and drying a PEDOT (i.e., 3,4-ethylenedioxythiophene):PSS (i.e., polystyrene sulfonic acid) solution with added carbon nanotubes.

[0032] The present invention relates to a nerve conduit with a composite conductive ink-modified coating (i.e., a conductive coating) on ​​the nerve conduit body. This conductive coating is prepared by coating and drying a PEDOT:PSS solution containing carbon nanotubes. It can significantly reduce the impedance of the scaffold material, improve the charge transfer capability, and promote biochemical signal transmission and activate signal pathways related to nerve regeneration by changing the bioelectric field, thereby regulating nerve cell behavior and promoting the healing of peripheral nerves after injury. At the same time, it overcomes the prominent problems faced by using electroactive materials alone, such as functionalization difficulties, lack of biodegradability, poor solubility and processability, and insufficient mechanical properties.

[0033] Furthermore, compared to the traditional method of using cellulose as the dispersant for CNTs, the CNT / pedot composite bio-conductive ink of the present invention uses PEDOT:PSS solution as the dispersant for CNTs, which not only further enhances the conductivity of the coating, but also improves the stability of the conductive coating and makes the coating exhibit a harderness that is more compatible with the nerve tissue interface.

[0034] In addition, the modification with a conductive coating further improves the hydrophilicity and cell compatibility of the PCL catheter scaffold surface, which is conducive to the attachment, spreading and growth of nerve cells on the catheter surface, thereby promoting the regeneration of damaged peripheral nerves. At the same time, it can also generate directional currents in the same direction as the topological microstructure of the catheter surface, enhancing the guiding effect on the directional alignment of nerve cells, thereby promoting the regeneration of damaged peripheral nerves.

[0035] To further improve the performance of the nerve conduit of the present invention, a crosslinking agent layer can be provided on the conductive coating. By providing the crosslinking agent layer, the stability of the nerve conduit and its conductivity can be further improved. For the selection of the crosslinking agent, a silane coupling agent can be used. For example, a silane coupling agent can be dissolved in alcohol to obtain the crosslinking agent. The nerve conduit body is then immersed in the crosslinking agent, removed, and dried to obtain the crosslinking agent layer. The crosslinking agent can be obtained by mixing a silane coupling agent and alcohol at a volume ratio of 1:10, with 75% alcohol being a suitable choice.

[0036] For the conductive layer, it is preferred to set two or more layers. In order to increase the conductivity of the nerve conduit while ensuring the hardness of the interface with the nerve tissue, the number of conductive layers (or the thickness of the conductive layer) can be determined by the conductivity. The preferred conductivity is 3-25s / m.

[0037] To enhance the guiding and stability performance of the nerve conduit body, it can be configured as follows: the nerve conduit body includes a guiding structure and a supporting structure. The guiding structure comprises multiple guiding fibers extending along the axis of the conduit. The supporting structure includes multiple spaced-apart supporting rings. Each guiding rib is spaced around the circumference of the supporting rings and connects to each supporting ring, with the supporting rings and guiding ribs forming the nerve conduit as a whole. This configuration, with its guiding structure consisting of multiple guiding ribs, can directionally regulate the arrangement and growth of nerve cells. Simultaneously, the multiple supporting rings, connected to the guiding ribs, significantly improve the overall strength of the nerve conduit, enabling it to simultaneously possess both high strength and the ability to directionally regulate the arrangement of nerve cells.

[0038] To achieve more uniform guidance and control of nerve cells, the guide ribs can be evenly distributed around the circumference of the supporting ring ribs; this ensures that the spacing between the guide ribs is the same, resulting in better guidance and control.

[0039] For the artificial nerve conduit body of the present invention, in order to further enhance the directional arrangement and regulation of nerve cells, strip fibers can be selected as guide ribs. The diameter of the strip fibers can be further selected as 50-150μm. Strip fibers of this size are close to the diameter of nerve cells, which can play a directional role. In order to avoid the influence of nerve cells on adjacent guide ribs, the distance between any two guide ribs can be set. The distance between the guide ribs can be set to 1-10 times the diameter of the strip fiber, and a more preferred ratio is 1.3-6 times. This setting can not only avoid the interference of cells on adjacent guide ribs affecting their arrangement, but also prevent external fibrous tissue from invading the nerve conduit, thereby further improving the directional arrangement and regulation and safety.

[0040] For the guide ribs and support ring ribs, polycaprolactone (PCL) can be selected, as it has good biocompatibility and is safer to use. For the molecular weight of PCL, a polycaprolactone polymer with a molecular weight of 60,000-80,000 can be selected.

[0041] The spacing between supporting ring ribs, guide ribs, and the spacing between guide ribs can be selected according to actual needs. To better improve the overall strength and directional alignment performance of the nerve conduit, the following settings can be made:

[0042] The supporting ring is a ring structure formed by connecting the ends of strip-shaped fibers (e.g., strip-shaped spun fibers). The diameter of the strip-shaped fibers is d1, the diameter of the supporting ring is d2, and the distance between any two adjacent supporting rings is d3, where d1:d2 = 1:1.0-2.0, d1:d3 = 1:0.62-1.6; for example, the interval between any two adjacent supporting rings is 280-320μm, the inner diameter of the supporting ring is 2.0-2.7mm, and the supporting ring is a ring structure formed by connecting the ends of fibers with a diameter of 200-450μm.

[0043] Furthermore, the guide ribs are strip fibers with a diameter of d4, and the distance between any two adjacent guide ribs is d5, wherein d1:d4 = 1:0.11-0.5, d1:d5 = 1:0.44-1.5; if strip fibers with a diameter of 50-150μm are selected, the distance between any two adjacent guide ribs is 200-300μm.

[0044] The selection of the dimensions and spacing of the aforementioned guide ribs and support rings ensures good overall strength of the artificial conduit. The axial stiffness, radial stiffness, maximum yield, and maximum load tests all show excellent data, meeting the application requirements in neural tissue engineering. Furthermore, it effectively avoids interference between cells in different rows of guide ribs and also prevents external cells or fibers from affecting the nerve cells on the conduit.

[0045] To make the strength of the nerve conduit body more uniform, the guide ribs and each supporting ring rib are connected perpendicularly.

[0046] Each guide bar can be distributed on the inner circumferential side of the supporting ring bar; in this way, the external supporting ring bar can provide better support and protection.

[0047] The present invention also provides a method for preparing the above-mentioned nerve conduit body, comprising the following steps:

[0048] A1: Preparation of guide structure: Take a metal shaft, use a nozzle to spray molten guide rib material axially onto the surface of the metal shaft, and after cooling, form guide ribs. Repeat the above axial spraying method at intervals to form multiple guide ribs.

[0049] A2: Preparation of support structure: The molten support ring material is radially sprayed onto the surface of the metal shaft using a nozzle. The materials to be sprayed are connected end to end to form a ring and cooled to form a support ring. Multiple support rings are formed by spraying the material at intervals in the radial spraying method described above. Each support ring is connected with each guide rib to form the nerve conduit body as a whole.

[0050] The above method can be achieved through 3D printing near-field direct writing technology, which enables more controllable fabrication of personalized neural conduit bodies with high-precision micro-directional structures. Furthermore, the raw materials are simple to prepare, the manufacturing process is environmentally friendly, and the cost is low, making it suitable for industrial production applications. In this invention, near-field direct writing technology can be used to fabricate the guiding and supporting structures. For example, using a 3D printing device of model EFL-BP6601, polycaprolactone material is melted, and fabrication is carried out using a molten high-voltage electrostatic field-assisted direct writing method.

[0051] Furthermore, step A1 specifically involves: loading the guide ring material (such as PCL) into the barrel and melting it; lowering the nozzle to a position 1.5-2mm from the metal shaft; controlling the nozzle to perform axial spraying on the surface of the metal shaft; and cooling to form the first guide rib. Then, the metal shaft is rotated by a preset angle, and the nozzle is controlled to perform axial spraying on the surface of the metal shaft to obtain the second guide rib. This process is repeated multiple times to form multiple guide ribs.

[0052] In this invention, a further preferred embodiment is that step A1 specifically involves: loading and melting the support ring material (such as PCL) into a barrel; lowering the nozzle until it is in close contact with the metal shaft; rotating the metal shaft one revolution so that the PCL material sprayed from the nozzle completes radial spraying on the surface of the metal shaft and forms the first support ring; then moving the nozzle along the axial direction of the metal shaft a predetermined distance; and continuing radial spraying to form the second support ring. This process is repeated multiple times to form multiple spaced support rings. The support rings are connected together with each guide rib to form the nerve conduit body as a whole.

[0053] For specific preparation methods, the following examples can be given:

[0054] 1. Preparation of the guiding structure, including the following steps:

[0055] (1) The material was prepared by direct writing with high voltage electrostatic field assistance. The equipment was EFL-BP6601. The PCL was no more than 2 / 3 of the barrel volume. The heating temperature of the nozzle was set to 120℃. The material was left to melt.

[0056] (2) The receiving device is still a metal rotating shaft (or metal shaft), driven by a motor, which lowers the nozzle to a position 1.7mm away from the upper end of the metal rotating shaft 22;

[0057] (3) Control the nozzle to move a preset distance along the long axis of the metal shaft. During the movement, the molten material is extruded into fine filaments and adhered to the surface of the metal shaft along the long axis to prepare the guide ribs. After one strip structure is prepared, control the metal shaft to rotate a preset angle, and then control the nozzle to move in the opposite direction along the long axis of the shaft at the same speed, and adhere the extruded fine filaments to the surface of the metal shaft to prepare the next guide rib. Repeat this procedure until the shaft rotates 360° and then stops to complete the preparation of all guide ribs (i.e., guide structures).

[0058] (4) After preparation, first turn off the electrostatic field, then turn off the gas valve, and wait for the support structure to be prepared.

[0059] 2. Fabrication of the support structure, including the following steps:

[0060] (1) The material is prepared by direct melt extrusion. The equipment is EFL-BP6601. Polycaprolactone (PCL) is loaded into the barrel, not exceeding 2 / 3 of its volume. The heating temperature of the nozzle is set to 90°C. Wait for the material to melt.

[0061] (2) The receiving device is a metal rotating shaft, driven by a motor, which lowers the nozzle to the upper end of the metal rotating shaft and keeps it close to the metal rotating shaft;

[0062] (3) The stationary nozzle extrudes the molten material into filaments and attaches them to the uniformly rotating metal shaft with guide ribs to prepare the support ring ribs. After the preparation of one support ring rib is completed, the nozzle is controlled to move a certain distance along the long axis of the metal shaft and then extrudes the filaments again to deposit them on the uniformly rotating shaft to prepare the next support ring rib. This process is repeated to complete the preparation of all support ring ribs (i.e. support structures).

[0063] (4) After preparation, close the gas valve, remove the nerve conduit stent, package and sterilize it, and it can be used for nerve repair.

[0064] The different dimensions and spacing of the guide ribs and support ring ribs can be controlled by preset and adjusted melt direct writing process parameters such as nozzle diameter, shaft diameter, nozzle moving speed, nozzle moving distance, extrusion air pressure, receiving voltage, and metal shaft rotation speed, so as to adjust the various structural parameters of the nerve conduit body to be prepared.

[0065] To improve the safety of subsequent use of nerve conduits, sterilization can be performed after preparation and before packaging. A disinfectant can be prepared by combining 75% ethanol and 0.5% povidone-iodine, and then sterilization can be performed.

[0066] The method for preparing the nerve conduit with a composite conductive ink modified coating according to the present invention includes the following steps:

[0067] S1. Preparation of dopamine coating: Take the nerve conduit body, immerse it in dopamine hydrochloride buffer solution for 8-24 hours, then wash it with deionized water and vacuum dry it to obtain dopamine coating.

[0068] S2. Preparation of conductive coating: The nerve conduit body treated in step S1 is immersed in a PEDOT:PSS solution containing carbon nanotubes for 8-15 minutes, and then dried under vacuum to obtain a conductive coating.

[0069] In this invention, the preferred dopamine hydrochloride buffer solution in step S1 has a dopamine concentration of 2 mg / mL and a preferred pH of 8.5. The dopamine hydrochloride buffer solution can be prepared by dissolving dopamine in a Tris-HCl buffer solution, mixing and stirring until homogeneous, to obtain the dopamine hydrochloride buffer solution. Dopamine contains catechol groups, which can form semiquinone radicals, facilitating intramolecular charge transfer and intermolecular aggregation between the PEDOT backbone and semiquinone radicals, thereby further improving the conductivity of the nerve conduit of this invention.

[0070] In this invention, the PEDOT:PSS solution with added carbon nanotubes in step S2 is prepared by the following steps: 2,4-ethylenedioxythiophene:polystyrene sulfonic acid solution is dissolved in deionized water and stirred until homogeneous to obtain a dispersion solution; then, carbon nanotubes are added to the dispersion solution, and the mixture is stirred again to ensure uniform dispersion of the carbon nanotubes, resulting in a carbon nanotube solution; the carbon nanotube solution is ultrasonically treated and then centrifuged to separate the undispersed carbon nanotubes, thus obtaining the PEDOT:PSS solution with added carbon nanotubes. The centrifugation conditions can be set to 3000 rpm for 10 min, with 1-3 centrifugations, preferably 2; the stirring time can be set to 30-100 min.

[0071] In this invention, the mass concentration of PEDOT:PSS in the dispersion solution is 0.2-20 mg / mL; the mass concentration of carbon nanotubes in the PEDOT:PSS solution with added carbon nanotubes is 2 mg / mL.

[0072] In this invention, after step S2, step S3 is also included: preparation of the crosslinking agent layer: the nerve conduit body treated in step S2 is immersed in the crosslinking agent for 1-4 minutes and dried to obtain the crosslinking agent layer; the crosslinking agent is a silane coupling agent alcohol solution.

[0073] In step S1, the nerve conduit body can be soaked in dopamine hydrochloride buffer solution on a shaker and placed on the shaker for 3-24 hours, preferably 12 hours.

[0074] For vacuum drying, the preferred temperature is 40±3℃ and the preferred time is 12-18 min.

[0075] For step S2, after drying, step S2 can be repeated to obtain at least two layers of conductive coating.

[0076] The nerve conduit described in this invention can be used in medical devices and other products.

[0077] Example 1

[0078] A nerve conduit with a composite conductive ink modified coating, the nerve conduit comprising a nerve conduit body and a dopamine coating and a conductive coating disposed on the nerve conduit body, the conductive coating being a conductive coating obtained by coating and drying a PEDOT (i.e., 3,4-ethylenedioxythiophene):PSS (i.e., polystyrene sulfonic acid) solution with added carbon nanotubes.

[0079] The nerve conduit body includes a guide structure and a support structure; the guide structure includes multiple guide ribs arranged along the axial direction of the conduit; the support structure includes multiple spaced support ring ribs; each guide rib is spaced around the circumference of the support ring rib and connected to each support ring rib, and each support ring rib and each guide rib integrally form the nerve conduit;

[0080] The nerve conduit body is 10 mm long and 2.5 mm in inner diameter. The guide ribs are strip fibers with a diameter of 50-100 μm. The distance between any two adjacent guide ribs is 300 μm. The diameter of the support environment is 200 μm and the distance between any two adjacent support environments is 300 μm.

[0081] The nerve conduit body is manufactured through the following steps:

[0082] A1: The preparation of the guide structure includes the following steps: It is prepared using a direct writing method assisted by a high-voltage electrostatic field in a molten state. The equipment is an EFL-BP6601, the PCL does not exceed 2 / 3 of the barrel volume, the nozzle diameter is 200μm, and the nozzle heating temperature is set to 120℃. The material is then allowed to melt. The receiving device is still a metal rotating shaft with a diameter of 2.5mm, driven by a motor, which lowers the nozzle to a position 1.7mm from the upper end of the metal rotating shaft. The extrusion pressure is controlled at 300kPa, and the voltage of the high-voltage electrostatic field between the nozzle and the metal rotating shaft is 4-5kV. The nozzle moves uniformly along the long axis of the rotating shaft at a speed of 200mm / min for 15mm. During this movement, the molten material is extruded and adheres to the metal rotating shaft to form guide ribs. After one guide rib is prepared, the rotating shaft rotates 13.75° at a speed of 30-35r / min, and then the nozzle moves uniformly in the opposite direction along the long axis of the rotating shaft at the same speed for 15mm to form the next guide rib. Repeat this procedure until the shaft has rotated 360° and then stops, to complete the preparation of the guided rib (i.e., the guide structure);

[0083] After the guide structure is prepared, the electrostatic field is turned off first, then the gas valve is turned off, and wait for the support structure to be prepared.

[0084] A2: The support structure is prepared using direct melt extrusion on an EFL-BP6601 machine. Polycaprolactone (PCL) is loaded into the barrel, filling it to no more than 2 / 3 of its volume. The nozzle diameter is 200 μm, and the nozzle heating temperature is set to 90°C. The material is then allowed to melt. A receiving device, a metal shaft driven by a motor, lowers the nozzle to the top of the shaft, ensuring it is tightly against the shaft. The extrusion pressure is controlled at 200 kPa. The stationary nozzle then presses the melt... The material is extruded into filaments and adhered to a metal shaft with a strip structure that rotates at a constant speed of 4-6 r / min to prepare the support ring ribs. After the preparation of one support ring rib is completed, the nozzle is controlled to move 300 μm along the long axis of the metal shaft at a speed of 30 mm / min and then extruded into filaments again to deposit them on the rotating shaft at a constant speed to prepare the next support ring rib. This process is repeated until the total distance the nozzle moves is 15 mm to complete the preparation of all support ring ribs (i.e. support structures).

[0085] After the ring structure is prepared, the gas valve is closed to complete the preparation of the nerve conduit body.

[0086] The nerve conduit is prepared through the following steps:

[0087] S1. Preparation of dopamine coating: Take the nerve conduit body and immerse it in dopamine hydrochloride buffer solution for 12 hours (the dopamine hydrochloride buffer solution is placed on a shaker). Then wash with deionized water and vacuum dry (vacuum dry at 40℃ for 15 minutes) to obtain dopamine coating. The preparation of dopamine hydrochloride buffer solution is as follows: Dissolve dopamine in tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer solution with a pH of 8.5 and mix. Stir evenly to prepare a dopamine hydrochloride buffer solution with a mass concentration of 2 mg / mL.

[0088] S2. Preparation of the conductive coating: The nerve conduit body treated in step S1 is immersed in a PEDOT:PSS solution containing carbon nanotubes for 10 min, and then vacuum dried (vacuum dried at 40℃ for 15 min) to obtain the conductive coating; the PEDOT:PSS solution containing carbon nanotubes is prepared as follows: 2,4-ethylenedioxythiophene:polystyrene sulfonic acid solution is dissolved in deionized water and stirred evenly (stirred with a magnetic stirrer for 1 h) to obtain a dispersion solution; then carbon nanotubes are added to the dispersion solution and stirred again (using a magnetic stirrer). The carbon nanotubes were stirred for 1 hour to disperse them evenly, resulting in a carbon nanotube solution. The carbon nanotube solution was then sonicated for 30 minutes and centrifuged twice (3000 rpm for 10 minutes) to separate the undispersed carbon nanotubes, yielding a PEDOT:PSS solution with added carbon nanotubes. The mass concentration of PEDOT:PSS in the dispersed solution was 2 mg / mL. The mass concentration of carbon nanotubes in the PEDOT:PSS solution with added carbon nanotubes was also 2 mg / mL.

[0089] Repeat step S2 9 times to obtain the nerve conduit; then perform cross-linking treatment, i.e., step S3, specifically: S3, preparation of cross-linking agent layer: immerse the nerve conduit body treated in step S2 in the cross-linking agent for 2 minutes, and dry it to obtain the cross-linking agent layer; the cross-linking agent is a silane coupling agent alcohol solution.

[0090] Under the above conditions, five nerve conduits were prepared for testing. Before cross-linking treatment, the conductivity of the conduits was measured to be 14.4771±11.7671 S / m, and the resistance was 1.32±1.284 KΩ. After cross-linking treatment, the conductivity decreased slightly, and the resistance increased slightly, but the impact on the overall conductivity of the conduits was not significant. The physical properties of the above nerve conduits were tested, and the radial stiffness was 0.2306±0.0507%, the axial stiffness was 92.1404±44.7677 KPa, the maximum stress was 499.2128±248.6686 MPa, and the maximum load was 1.5594±0.7742 N.

[0091] Example 2

[0092] Same as Example 1, except that step S2 is repeated 6 times, and the resulting catheter length, inner diameter, structural spacing, etc. are the same as in Example 1.

[0093] Under the same conditions, five nerve conduits were prepared for testing. Before crosslinking treatment, the conductivity of the conduits was measured to be 4.7029±3.8829 S / m, and the resistance was 4.048±4.1056 KΩ. After crosslinking treatment, the conductivity decreased slightly, and the resistance increased slightly. The mechanical properties, such as radial stiffness, axial stiffness, maximum stress, and maximum load, were basically the same as those in Example 1.

[0094] Example 3

[0095] Same as Example 1, except that the mass concentration of PEDOT:PSS solution in S2 is changed to 4 mg / mL, and the length, inner diameter, and structural spacing of the resulting catheter are the same as in Example 1.

[0096] Under the same conditions, five nerve conduits were prepared for testing. Before cross-linking treatment, the conductivity of the conduits was measured to be 10.1029±6.6121 S / m, and the resistance was 1.9575±1.415 KΩ. After cross-linking treatment, the conductivity decreased slightly, and the resistance increased slightly, but the impact on the overall conductivity of the conduits was not significant. The mechanical properties, such as radial stiffness, axial stiffness, maximum stress, and maximum load, were basically the same as those in Example 1.

[0097] Experiment Example 1 (In vivo animal experiment)

[0098] Experimental animals: Six healthy adult male SD rats, weighing 180-220g.

[0099] Animal surgical procedure: Sevoflurane inhalation anesthesia was performed. A midline incision was made in the posterior thigh to expose the sciatic nerve in the middle segment of the right hind limb. 13 mm of the sciatic nerve was removed, and the peripheral nerve composite conduit manufactured in Example 1 was transplanted to the sciatic nerve defect site. After conduit transplantation, the anastomosis was sutured with surgical sutures, and the muscles and skin were sutured. On the day of surgery, 100 mV 50 Hz AC stimulation was applied using an external power source for 30 minutes. On the second day after surgery, 100 mV DC stimulation was applied for 30 minutes. On the seventh day after surgery, 200 mV DC stimulation was applied for 30 minutes. On the 21st day after surgery, 300 mV DC stimulation was applied for 30 minutes. After surgery, the rats were fed routinely. At 12 weeks post-surgery, the regenerated nerve tissue from 6 rats was harvested, with a length of approximately 2 cm. The tissue was fixed, dehydrated, cleared, paraffin-embedded, and embedded. Three of the tissue samples were transversely stained with toluidine blue (TB staining), and the other three were longitudinally stained with hematoxylin and eosin (HE).

[0100] TB staining image after tissue transverse section is shown in Figure 1. Figure 2 (X10), Figure 3 (X40). HE staining image after longitudinal section of tissue is shown below. Figure 4 (X10), Figure 5 (X40)

[0101] Depend on Figure 2 , Figure 3 , Figure 4 , Figure 5 As can be seen, at 12 weeks post-implantation, the conduit was completely degraded, the regenerated nerve structure was continuous, the myelin sheath thickness was uniform, regeneration was good, there were no signs of neuroma formation, inflammatory cell infiltration was minimal, there was no obvious adhesion to surrounding tissues, and no scar formation, forming an anatomical structure similar to normal nerve tissue. This demonstrates that the highly conductive nerve conduit modified with CNT / PEDOT composite conductive bio-ink produced in this invention, combined with exogenous electrical stimulation, can effectively promote regeneration of peripheral nerves after injury.

[0102] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A nerve conduit with a composite conductive ink-modified coating, characterized in that, The nerve conduit includes a nerve conduit body, and a dopamine coating and a conductive coating disposed on the nerve conduit body. The conductive coating is prepared by coating and drying a PEDOT:PSS solution containing carbon nanotubes. A crosslinking agent layer is also disposed on the conductive coating. The preparation method of the nerve conduit includes the following steps: S1. Preparation of dopamine coating: Take the nerve conduit body, immerse it in dopamine hydrochloride buffer solution for 8-24 hours, then wash it with deionized water and vacuum dry it to obtain dopamine coating. S2. Preparation of conductive coating: The nerve conduit body treated in step S1 is immersed in a PEDOT:PSS solution containing carbon nanotubes for 8-15 minutes, and then dried under vacuum to obtain a conductive coating. The process includes step S3 after step S2: preparation of the crosslinking agent layer: the nerve conduit body treated in step S2 is immersed in the crosslinking agent for 1-4 minutes and then dried to obtain the crosslinking agent layer; the crosslinking agent is a silane coupling agent alcohol solution.

2. The nerve conduit according to claim 1, characterized in that, The conductive coating consists of at least two layers.

3. The nerve conduit according to claim 1, characterized in that, The nerve conduit body includes a guide structure and a support structure; the guide structure includes multiple guide fibers arranged along the axial direction of the conduit; the support structure includes multiple spaced support rings; each guide rib is spaced around the circumference of the support ring and connected to each support ring, and each support ring and each guide rib integrally form the nerve conduit.

4. The method for preparing a nerve conduit with a composite conductive ink-modified coating according to claim 1, characterized in that, Includes the following steps: S1. Preparation of dopamine coating: Take the nerve conduit body, immerse it in dopamine hydrochloride buffer solution for 8-24 hours, then wash it with deionized water and vacuum dry it to obtain dopamine coating. S2. Preparation of conductive coating: The nerve conduit body treated in step S1 is immersed in a PEDOT:PSS solution containing carbon nanotubes for 8-15 minutes, and then dried under vacuum to obtain a conductive coating. The process includes step S3 after step S2: preparation of the crosslinking agent layer: the nerve conduit body treated in step S2 is immersed in the crosslinking agent for 1-4 minutes and then dried to obtain the crosslinking agent layer; the crosslinking agent is a silane coupling agent alcohol solution.

5. The preparation method according to claim 4, characterized in that, In step S1, the dopamine hydrochloride buffer solution has a dopamine concentration of 2 mg / mL and a pH of 8.

5.

6. The preparation method according to claim 4, characterized in that, The PEDOT:PSS solution with added carbon nanotubes in step S2 is prepared by the following steps: 2,4-ethylenedioxythiophene:polystyrene sulfonic acid solution is dissolved in deionized water and stirred evenly to obtain a dispersion solution; then carbon nanotubes are added to the dispersion solution and stirred again to disperse the carbon nanotubes evenly to obtain a carbon nanotube solution; the carbon nanotube solution is ultrasonicated in an ultrasonic machine and then centrifuged in a centrifuge to separate the undispersed carbon nanotubes, thus obtaining the PEDOT:PSS solution with added carbon nanotubes.

7. The preparation method according to claim 6, characterized in that, The mass concentration of PEDOT:PSS in the dispersion solution is 0.2-20 mg / mL; the mass concentration of carbon nanotubes in the PEDOT:PSS solution with added carbon nanotubes is 2 mg / mL.

8. The use of a nerve conduit as described in any one of claims 1-3 in the manufacture of a medical device product.

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