Nerve repair catheter and its preparation method and application

Abstract

The present invention provides a nerve repair catheter and its preparation method and application, which relate to the technical field of nerve repair materials. The nerve repair catheter is mainly composed of an inner oriented fiber layer and an outer oriented fiber layer; wherein: the orientation direction of the oriented fibers in the inner oriented fiber layer is consistent with the axial direction of the nerve repair catheter; the orientation direction of the oriented fibers in the inner oriented fiber layer is different from the orientation direction of the oriented fibers in the outer oriented fiber layer, and is at an angle of 90°±15°. The above-mentioned nerve repair catheter in this application has the technical advantages of good nerve repair effect, good tissue cell affinity, and high mechanical strength compared to the existing nerve repair catheter, and can be widely used in the preparation of nerve defect repair bodies.

Description

Technical Field

[0001] The present invention relates to the technical field of nerve repair materials, and in particular to a nerve repair catheter and a preparation method and application thereof. Background Art

[0002] Surgical treatment of nerve injury is an important means to repair damaged nerves and restore their function. When the nerve defect is not large, nerve suturing is usually used to reconnect the two ends of the broken nerve to restore the continuity of the nerve; when the nerve defect is large and its continuity cannot be restored by direct suturing, nerve transplantation is required. At present, nerve transplantation mostly uses autologous nerve transplantation materials in clinical practice, but the source of autologous nerves is limited, and it will cause secondary damage to the human body. The operation is difficult, and there are problems such as difficulty for patients to fully recover. Therefore, the use of nerve repair catheters to repair peripheral nerve defects has been a hot topic in the field of peripheral nerves in recent years. Nerve repair catheters are a medical device used to promote nerve regeneration and repair. By implanting nerve repair catheters, the broken ends of the nerves can be effectively bridged, nerve regeneration can be promoted, and the patient's nerve function can be restored.

[0003] The material sources of nerve repair catheters at home and abroad are mainly concentrated in animal type I collagen, human allogeneic sources, and artificial synthetic materials. Animal type I collagen and human allogeneic sources have immunogenicity problems, that is, due to the existence of postoperative immune rejection reactions, patients have to take immunosuppressants for a long time, which not only causes damage to other organs of patients, but also greatly increases the risk of patients suffering from malignant tumors. In addition, nerve repair catheters derived from human allogeneic sources still have many problems in clinical use, such as weak cell adsorption and degradation products that easily cause local inflammatory reactions, which may affect nerve regeneration and repair. And because the source of its raw materials is particularly limited and the preparation process is complicated, the cost is high. Existing nerve repair catheters derived from artificial synthetic materials often have problems such as low mechanical strength, uncontrollable degradation, and poor nerve repair effect.

[0004] It is necessary and urgent to research and develop a nerve repair catheter with good nerve repair effect, good tissue cell affinity and high mechanical strength. In view of this, the present invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a nerve repair catheter, which has the technical advantages of good nerve repair effect, good tissue cell affinity and high mechanical strength.

[0006] The second object of the present invention is to provide a method for preparing a nerve repair catheter.

[0007] The third object of the present invention is to provide an application of a nerve repair catheter.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] The present invention provides a nerve repair catheter, which is mainly composed of an inner oriented fiber layer and an outer oriented fiber layer;

[0010] The orientation direction of the oriented fibers in the inner oriented fiber layer is consistent with the axial direction of the nerve repair catheter;

[0011] The orientation direction of the oriented fibers in the inner oriented fiber layer is different from the orientation direction of the oriented fibers in the outer oriented fiber layer, and the orientation direction forms an angle of 90°±15°.

[0012] Furthermore, the diameter of the oriented fibers in the inner oriented fiber layer is 1 nm to 10 μm, and the porosity is 30 to 80%;

[0013] And / or, the diameter of the oriented fibers in the outer oriented fiber layer is 1 nm to 10 μm, and the porosity is 5 to 20%.

[0014] Further, the inner diameter of the nerve repair catheter is 1 to 8 mm, preferably 2 to 6 mm;

[0015] The thickness of the inner oriented fiber layer is 0.02-0.7 mm, the thickness of the outer oriented fiber layer is 0.03-0.8 mm, and the thickness of the nerve repair conduit is 0.05-1.5 mm.

[0016] Furthermore, the oriented fibers are obtained by electrostatic spinning of degradable polyurethane or polylactic acid;

[0017] Preferably, the weight average molecular weight Mw of the degradable polyurethane is 12W to 16W;

[0018] Preferably, the weight average molecular weight Mw of the polylactic acid is 15W to 30W.

[0019] Furthermore, the maximum tensile force of the nerve repair conduit is 50-100N, the elongation at break is 300-650%, the elastic modulus is 120-165Mpa, and the degradation period is 4-8 months.

[0020] Furthermore, the nerve repair catheter also includes an outer coating layer, and the outer coating layer is arranged on the outer oriented fiber layer.

[0021] The present invention provides a method for preparing a nerve repair catheter, the method comprising:

[0022] (A) dissolving a degradable polyurethane in a solvent to obtain a spinning solution, and electrospinning to obtain a fiber orientation sheet A; preparing the fiber orientation sheet A into a tube shape to obtain an intermediate conduit; the orientation direction of the oriented fibers on the inner wall of the intermediate conduit is consistent with the axial direction of the conduit;

[0023] (B) Electrospinning is performed on the intermediate conduit to form an oriented fiber layer, wherein the orientation direction of the oriented fibers in the oriented fiber layer is at an angle of 90°±15° to the orientation direction of the oriented fibers in the intermediate conduit, and the solvent is removed to obtain a nerve repair conduit having inner and outer oriented fiber layers.

[0024] Furthermore, the concentration of the degradable polyurethane in the spinning solution is 5 to 40% (w / v);

[0025] Preferably, the solvent in the spinning solution is a single solvent of N,N-dimethylformamide, a single solvent of N,N-dimethylacetamide, a mixed solvent of N,N-dimethylformamide and any one or more of tetrahydrofuran, dichloroethane or dimethyl ether, or a mixed solvent of N,N-dimethylacetamide and any one or more of tetrahydrofuran, dichloroethane or dimethyl ether;

[0026] More preferably, the solvent in the spinning solution is a mixed solvent of N,N-dimethylformamide and tetrahydrofuran, wherein the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 10:1-3:7, wherein the preferred volume ratio is 10:1-1:1.

[0027] Furthermore, the conditions for electrospinning the inner oriented fiber layer include:

[0028] Negative voltage: -1KV~-4KV, positive voltage: 8KV~10KV, injection speed of the nozzle: 0.08-0.7ml / min; rotation speed of the receiving device: (1000, 2500) rpm / min; distance between the nozzle and the receiving device: 0~50mm; translation speed of the nozzle is (50, 450) mm / min.

[0029] The conditions for electrospinning the outer oriented fiber layer include:

[0030] Negative voltage: -1KV~-4KV, positive voltage: 8KV~10KV, injection speed of the nozzle: 0.08-0.3ml / min; rotation speed of the receiving device: (800, 2000) rpm / min; distance between the nozzle and the receiving device: 0~50mm; translation speed of the nozzle is (0, 250) mm / min.

[0031] The invention provides an application of a nerve repair catheter in preparing a nerve defect repair body.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The nerve repair catheter provided by the present invention is mainly composed of an inner oriented fiber layer and an outer oriented fiber layer; wherein: the orientation direction of the oriented fibers in the inner oriented fiber layer is consistent with the axial direction of the nerve repair catheter; the orientation direction of the oriented fibers in the inner oriented fiber layer is different from the orientation direction of the oriented fibers in the outer oriented fiber layer, and is at an angle of 90°±15°. The structural setting of the above-mentioned nerve repair catheter in this application has the following technical advantages:

[0034] 1. The oriented fiber directions of the inner oriented fiber layer and the outer oriented fiber layer in the nerve repair catheter of the present application are arranged crosswise, and the crossing angle is 90°±15°, thereby greatly enhancing the mechanical strength of the nerve repair catheter of the present application;

[0035] 2. The orientation direction of the oriented fibers in the inner oriented fiber layer of the nerve repair catheter of the present application is consistent with the axial direction of the nerve repair catheter, which is beneficial to guide the repair nerve to grow along the axial direction of the nerve repair catheter, thereby improving the efficiency and accuracy of nerve repair.

[0036] 3. The oriented fiber directions of the inner oriented fiber layer and the outer oriented fiber layer in the nerve repair catheter of the present application are arranged crosswise, and only two layers are needed to achieve high strength, and the inner oriented structural layer has a high porosity, which is conducive to the proliferation of nerve cells and the flow of nutrients, which is conducive to cell growth and tissue regeneration. The porosity of the outer oriented fiber layer is relatively low. Under this porosity, the outer oriented fiber layer of the present application can block fibroblasts, inflammatory cells, muscle and vascular tissue cells from invading the lumen and inner oriented fiber layer of the nerve repair catheter, and prevent other cells from affecting the growth and proliferation of nerve cells; at the same time, the outer layer porosity of 5-20% is also convenient for the flow of nutrients, which is conducive to nerve regeneration.

[0037] The preparation method of the nerve repair catheter provided by the present invention first prepares a fiber orientation sheet A by electrospinning, then prepares the fiber orientation sheet A into a tube shape to obtain an intermediate catheter (inner layer), and then electrospins on the intermediate catheter to form an oriented fiber layer (outer layer); wherein: the orientation direction of the oriented fibers in the oriented fiber layer is at an angle of 90° to the orientation direction of the oriented fibers in the intermediate catheter. The orientation directions of the oriented fibers in the inner and outer layers of the nerve repair catheter obtained by the above-mentioned preparation method of the present application are perpendicularly crossed at 90°, and have good mechanical strength after testing. At the same time, the oriented fiber layer of the two-layer structure has a high porosity, which is convenient for the flow of nutrients, and is beneficial to cell growth and tissue regeneration.

[0038] The nerve repair conduit provided by the present invention can be widely used in the preparation process of nerve defect repair bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 The electrospinning receiving device for preparing a sheet-like oriented fiber sheet provided in Example 1 of the present invention;

[0041] Figure 2 The electrospinning receiving device provided with an intermediate conduit provided in Example 1 of the present invention;

[0042] Figure 3a A scanning electron microscope image of oriented fibers of the electrospun oriented fiber layer 1 provided in Example 1 of the present invention;

[0043] Figure 3b This is a scanning electron microscope image of oriented fibers of the electrospun oriented fiber layer 2 provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] According to one aspect of the present invention, a nerve repair catheter is provided, the nerve repair catheter mainly consisting of an inner oriented fiber layer and an outer oriented fiber layer;

[0046] The orientation direction of the oriented fibers in the inner oriented fiber layer is consistent with the axial direction of the nerve repair catheter;

[0047] The orientation direction of the oriented fibers in the inner oriented fiber layer is different from the orientation direction of the oriented fibers in the outer oriented fiber layer, and the orientation direction forms an angle of 90°±15°.

[0048] The nerve repair catheter provided by the present invention is mainly composed of an inner oriented fiber layer and an outer oriented fiber layer; wherein: the orientation direction of the oriented fibers in the inner oriented fiber layer is consistent with the axial direction of the nerve repair catheter; the orientation direction of the oriented fibers in the inner oriented fiber layer is different from the orientation direction of the oriented fibers in the outer oriented fiber layer, and is at an angle of 90°±15°. The structural setting of the above-mentioned nerve repair catheter in this application has the following technical advantages:

[0049] 1. The oriented fiber directions of the inner oriented fiber layer and the outer oriented fiber layer in the nerve repair catheter of the present application are arranged crosswise, and the crossing angle is 90°±15°, thereby greatly enhancing the mechanical strength of the nerve repair catheter of the present application;

[0050] 2. The orientation direction of the oriented fibers in the inner oriented fiber layer of the nerve repair catheter of the present application is consistent with the axial direction of the nerve repair catheter, which is beneficial to guide the repair nerve to grow along the axial direction of the nerve repair catheter, thereby improving the efficiency and accuracy of nerve repair.

[0051] 3. The oriented fiber directions of the inner oriented fiber layer and the outer oriented fiber layer in the nerve repair catheter of the present application are arranged crosswise, and only two layers are needed to achieve high strength, and the inner oriented structural layer has a high porosity, which is conducive to the proliferation of nerve cells and the flow of nutrients, which is conducive to cell growth and tissue regeneration. The porosity of the outer oriented fiber layer is relatively low. Under this porosity, the outer oriented fiber layer of the present application can block fibroblasts, inflammatory cells, muscle and vascular tissue cells from invading the lumen and inner oriented fiber layer of the nerve repair catheter, and prevent other cells from affecting the growth and proliferation of nerve cells; at the same time, the outer layer porosity of 5-20% is also convenient for the flow of nutrients, which is conducive to nerve regeneration.

[0052] It should be noted that the orientation directions of the oriented fibers in the inner oriented fiber layer of the present invention are consistent, and the orientation directions of the oriented fibers in the outer oriented fiber layer of the present invention are consistent.

[0053] In a preferred embodiment of the present invention, the diameter of the oriented fibers in the inner oriented fiber layer is 1 nm to 10 μm, and the porosity is 30 to 80%;

[0054] It should be noted that the inner layer of the nerve repair catheter is mainly used for the regeneration and repair of nerve cells. The cells involved in nerve regeneration and repair are as follows:

[0055] (1) Schwann cells are the cell type responsible for forming the myelin sheath in the peripheral nervous system. They are generally small in size, with a diameter usually between 10 and 30 microns, and their specific size may vary depending on individual differences and different functional states.

[0056] (2) The size of nerve cells (neurons) varies depending on their type and function. Generally speaking, the diameter of neurons is usually between 10 and 100 microns. The following are the size ranges of some common neuron types. Motor neurons: Usually larger, with a diameter of up to 50 to 100 microns, with longer axons, responsible for transmitting motor signals. Sensory neurons: Generally between 20 and 100 microns in diameter, responsible for receiving signals from the senses. Connecting neurons (interneurons): Relatively small, usually between 10 and 30 microns in diameter, mainly play a role in information transmission and integration in the central nervous system. In addition, the length of the axon of neurons also varies greatly, ranging from a few millimeters to more than a meter (for example, the axons of motor neurons in some parts of the body can extend to the distal ends of the limbs). Overall, the size and shape of nerve cells give them unique functions and characteristics.

[0057] Research has found that nerve cells have better adhesion properties on fibers with a diameter smaller than their own. Therefore, the diameter of the oriented fibers in the inner oriented fiber layer is set to 1nm to 10μm, and the porosity is 30 to 80%, which has been proven to have a better nerve repair effect.

[0058] In a preferred embodiment of the present invention, the diameter of the oriented fibers in the outer oriented fiber layer is 1 nm to 10 μm, and the porosity is 5 to 20%.

[0059] It should be noted that the outer layer of the nerve repair catheter is mainly used for the regeneration and repair of extravascular tissue cells. The cells involved in vascular repair are as follows:

[0060] Endothelial cells: Endothelial cells are the main component of the blood vessel wall and are usually between 10 and 25 microns in diameter. They are involved in the regeneration and repair of blood vessels and promote blood vessel healing by forming a new endothelial layer. Smooth muscle cells: These cells are located in the middle layer of the blood vessels and are responsible for the contraction and relaxation of the blood vessels. They are usually 10 to 20 microns in diameter. They proliferate after blood vessel damage and participate in rebuilding the blood vessel structure. Fibroblasts: These cells play an important role in the blood vessel repair process and are usually 10 to 30 microns in diameter. They are responsible for synthesizing collagen and other matrix components to promote the repair of the blood vessel wall. Macrophages: These immune cells play a role in the removal of dead cells and pathogens and are usually 10 to 30 microns in diameter. They play an important role in the inflammatory response and tissue repair at the site of injury. Platelets: Although they are not cells, platelets are also very important in the blood vessel repair process. They are about 2 to 4 microns in diameter and participate in the clotting process and release growth factors to promote repair.

[0061] As a preferred embodiment, the porosity of the outer oriented fiber layer of the present application is 5-20%. At this porosity, the outer oriented fiber layer of the present application can block fibroblasts, inflammatory cells, muscle and vascular tissue cells, etc. from invading the lumen and inner oriented fiber layer of the nerve repair catheter; at the same time, the outer layer porosity of 5-20% also facilitates the flow of nutrients, which is beneficial to nerve regeneration.

[0062] In a preferred embodiment of the present invention, the inner diameter of the nerve repair catheter is 1 to 8 mm, preferably 2 to 6 mm. The inner diameter of the nerve repair catheter can be, but is not limited to, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm or 8 mm, and can also be any value between 1 mm and 8 mm.

[0063] In a preferred embodiment of the present invention, the thickness of the inner oriented fiber layer is 0.02-0.7 mm, the thickness of the outer oriented fiber layer is 0.03-0.8 mm, and the thickness of the nerve repair conduit is 0.05-1.5 mm.

[0064] The thickness of the inner oriented fiber layer may be, but is not limited to, 0.02 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, or 0.7 mm, or any value between 0.02 and 0.7 mm. The thickness of the outer oriented fiber layer may be, but is not limited to, 0.03 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, or 0.8 mm, or any value between 0.03 and 0.8 mm. The thickness of the nerve repair catheter may be, but is not limited to, 0.05 mm, 0.1 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, or 1.5 mm, or any value between 0.05 and 1.5 mm.

[0065] In a preferred embodiment of the present invention, the oriented fibers are obtained by electrospinning degradable polyurethane or polylactic acid;

[0066] Preferably, the weight average molecular weight Mw of the degradable polyurethane is 12W to 16W;

[0067] Preferably, the weight average molecular weight Mw of the polylactic acid is 15W to 30W.

[0068] The weight average molecular weight of the degradable polyurethane may be, but not limited to, 12W, 13W, 14W, 15W or 16W, or any value between 12W and 16W. The weight average molecular weight of the polylactic acid may be, but not limited to, 15W, 16W, 17W, 18W, 19W, 20W, 21W, 22W, 23W, 24W, 25W, 26W, 27W, 28W, 29W or 30W, or any value between 15W and 30W.

[0069] In a preferred embodiment of the present invention, the maximum tensile force of the nerve repair conduit is 50-100N, the elongation at break is 300-650%, the elastic modulus is 120-165Mpa, and the degradation period is 4-8 months.

[0070] In a preferred embodiment of the present invention, the nerve repair catheter further comprises an outer coating layer, and the outer coating layer is disposed on the outer oriented fiber layer.

[0071] As a preferred embodiment, the nerve repair catheter of the present application may also be optionally provided with an outer coating layer, wherein the outer coating layer is a microporous membrane layer for preventing the growth of non-neural cells such as fibroblasts.

[0072] According to one aspect of the present invention, a method for preparing a nerve repair catheter comprises:

[0073] (A) dissolving a degradable polyurethane in a solvent to obtain a spinning solution, and electrospinning to obtain a fiber orientation sheet A; preparing the fiber orientation sheet A into a tube shape to obtain an intermediate conduit; the orientation direction of the oriented fibers on the inner wall of the intermediate conduit is consistent with the axial direction of the conduit;

[0074] (B) Electrospinning is performed on the intermediate conduit to form an oriented fiber layer, wherein the orientation direction of the oriented fibers in the oriented fiber layer is at a 90° angle to the orientation direction of the oriented fibers in the intermediate conduit, and the solvent is removed to obtain a nerve repair conduit having inner and outer oriented fiber layers.

[0075] The preparation method of the nerve repair conduit provided by the present invention first prepares a fiber orientation sheet A by electrospinning, then prepares the fiber orientation sheet A into a tube shape to obtain an intermediate conduit (inner layer), and then electrospins on the intermediate conduit to form an oriented fiber layer (outer layer); wherein: the orientation direction of the oriented fibers in the oriented fiber layer is at an angle of 90° to the orientation direction of the oriented fibers in the intermediate conduit. The orientation directions of the oriented fibers in the inner and outer layers of the nerve repair conduit obtained by the above-mentioned preparation method of the present application are vertically crossed at 90°, and it has been tested to have better mechanical strength. At the same time, the two-layer structure has a high porosity, which is convenient for the flow of nutrients, and is beneficial to cell growth and tissue regeneration.

[0076] In a preferred embodiment of the present invention, the concentration of the degradable polyurethane in the spinning solution is 5 to 40% (w / v);

[0077] Preferably, the solvent in the spinning solution is a single solvent of N,N-dimethylformamide, a single solvent of N,N-dimethylacetamide, a mixed solvent of N,N-dimethylformamide and any one or more of tetrahydrofuran, dichloroethane or dimethyl ether, or a mixed solvent of N,N-dimethylacetamide and any one or more of tetrahydrofuran, dichloroethane or dimethyl ether;

[0078] More preferably, the solvent in the spinning solution is a mixed solvent of N,N-dimethylformamide and tetrahydrofuran, wherein the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 10:1-3:7, wherein the preferred volume ratio is 10:1-1:1.

[0079] In a preferred embodiment of the present invention, the conditions for electrospinning the inner oriented fiber layer include: negative voltage: -1KV to -4KV, positive voltage: 8KV to 10KV, injection speed of the nozzle: 0.08-0.7ml / min; rotation speed of the receiving device: (1000, 2500) rpm / min; distance between the nozzle and the receiving device: 0 to 50mm; translation speed of the nozzle is (50, 450) mm / min;

[0080] The conditions for electrospinning the outer oriented fiber layer include: negative voltage: -1KV~-4KV, positive voltage: 8KV~10KV, injection speed of the nozzle: 0.08-0.3ml / min; rotation speed of the receiving device: (800, 2000) rpm / min; distance between the nozzle and the receiving device: 0~50mm; translation speed of the nozzle is (0, 250) mm / min.

[0081] As a preferred embodiment, oriented spinning fibers can be produced under the above-mentioned electrospinning conditions, thereby realizing the preparation of fiber oriented sheets with consistent fiber orientation directions.

[0082] According to one aspect of the present invention, a nerve repair catheter is used in preparing a nerve defect repair body.

[0083] The nerve repair conduit provided by the present invention can be widely used in the preparation process of nerve defect repair bodies.

[0084] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0085] Example 1

[0086] A method for preparing a nerve repair catheter, the method comprising:

[0087] (I) Preparation of degradable polyurethane (PU) solution

[0088] A 26% polyurethane solution was prepared using a degradable polyurethane (weight average molecular weight Mw of 12W) as a solute and a mixed solution of tetrahydrofuran (THF):N,N-dimethylformamide (DMF) as a solvent. The ratio of the solvent was: tetrahydrofuran (THF):N,N-dimethylformamide (DMF) = 1:1.

[0089] The specific preparation operation is as follows:

[0090] (1) Add (150 mL) tetrahydrofuran and (150 mL) N,N-dimethylformamide into a three-necked flask, turn on the stirrer, adjust the speed to (200 ± 100) r / min, and stir evenly.

[0091] (2) Weigh (78 g) polyurethane material and add it to a three-necked flask. Different volumes of solution can be prepared according to the amount of solution used, see Table 1 below.

[0092] (3) Stir at room temperature for more than 4 hours to completely dissolve the PU. Let stand for more than 4 hours to remove bubbles and set aside.

[0093] (ii) Electrospinning:

[0094] Figure 1 The invention discloses an electrospinning receiving device for preparing a sheet-like oriented fiber sheet.

[0095] Figure 2 The invention relates to an electrospinning receiving device provided with an intermediate conduit.

[0096] The electrospinning method comprises:

[0097] (1) Wipe the electrospinning machine clean and ensure that the equipment is in a clean state.

[0098] (2) Fix the release paper on the receiving device (large cylindrical receiving device) to ensure that the release paper is not loose.

[0099] (3) Adjust the distance between the spinneret and the receiver to 20 ± 1 cm, determine the position and clamp it.

[0100] (4) The receiver speed is set to (1500±100) rpm / min; the injection speed is set to 0.2±0.05 mm / min.

[0101] (5) The translation speed is set to 150±50 mm / min and the translation distance is set to 300±50 mm.

[0102] (6) Use the prepared (26%) PU solution and slowly draw the PU solution with a disposable syringe to avoid bubbles. If bubbles are generated, they must be removed before subsequent operations. Install a 22G needle and fix the syringe in the buckle of the electrospinning machine push pump.

[0103] The nozzle diameter range can be: 0.15-4.2mm, preferably 18G (inner diameter 0.9mm), 19G (inner diameter 0.84mm), 20G (inner diameter 0.62mm), 21G (inner diameter 0.51mm), 22G (inner diameter 0.41mm), 23G (inner diameter 0.33mm), 24G (inner diameter 0.3mm) needles. In this embodiment, a 22G needle is selected.

[0104] (7) The negative voltage is set to (-3±1) KV, and the positive voltage is set to (9±0.5) KV. Start electrospinning and observe the spinning effect until continuous and uniform yarn is ejected. Set the electrospinning time to 30 min to 4 h. Figure 1 A receiving device is used to obtain an electrospun oriented fiber layer 1.

[0105] (8) According to Figure 2 The length and outer diameter of the thin rod in the receiving device are determined, and the electrospun oriented fiber layer 1 is cut into long strips of matching size, and then bonded and wrapped in the thin rod with the help of medical glue or the solvent of the electrospinning solution. Figure 2 The fiber orientation direction of the electrostatically spun oriented fiber layer 1 is toward the longitudinal direction of the thin rod, and an inner oriented fiber layer is prepared.

[0106] (9) using the above-mentioned layer of electrospun oriented fiber layer 1 Figure 2 The receiving device is used for electrospinning. The injection speed of the nozzle is 0.15±0.05 ml / min; the rotation speed of the receiving device is (1000±100) rpm / min; the translation speed is set to 200±50 mm / min, and the other operation steps are the same as (1)-(7), forming a transversely oriented electrospun oriented fiber layer 2, that is, an outer oriented fiber layer is electrospun outside the inner oriented fiber layer.

[0107] Figure 3a This is a scanning electron microscope image of the oriented fibers of the electrospun oriented fiber layer 1 of this embodiment.

[0108] Figure 3b This is a scanning electron microscope image of the oriented fibers of the electrostatically spun oriented fiber layer 2 of this embodiment.

[0109] 3. Surface coating:

[0110] A 26% (w / v) polyurethane solution 2 (polyurethane dissolved in tetrahydrofuran solution without adding porogen) was cast onto the outer surface of the two layers of electrospun membrane to obtain a non-porous polyurethane membrane coated on the surface, which was then dried to obtain a multi-layer structure catheter.

[0111] 4. Post-processing:

[0112] (1) The rod-shaped tube with a multi-layer structure Figure 2 The receiving device is immersed in water and demoulded.

[0113] The multi-layer structure catheter is immersed in a water tank to remove the solvent until the total amount of residual solvent in the multi-layer structure catheter is ≦0.1%.

[0114] Change the water twice a day. The ratio of the patch surface area to the water volume in each water tank should be ≥900cm2 / L.

[0115] (2) Rinse the multi-layer structure catheter with injection water cooled to 30° C. and lay them flat on the partition rack of the oven.

[0116] The oven temperature is set at 35°C and dried until the moisture content in the multi-layer structure catheter is less than 0.5%. After drying, the appearance is inspected and the patch is cut into the required size.

[0117] Example 2

[0118] The difference from Example 1 is that the nerve conduit of this example is a two-layer structure, and the outer oriented fiber layer is not coated.

[0119] When electrospinning the inner layer: the speed of the receiving device is (1600±100) rpm / min, and the translation speed of the nozzle is (100±50) mm / min.

[0120] When electrospinning the outer layer: the speed of the receiving device is (1100±100) rpm / min, and the translation speed of the nozzle is (200±50) mm / min.

[0121] (The weight average molecular weight Mw of the degradable polyurethane used in Examples 1 and 2 is 12W. The porosity of the outer layer is about 20%, and the porosity of the inner layer is about 60%)

[0122] Example 3

[0123] The difference from Example 2 is that the weight average molecular weight Mw of the degradable polyurethane is 16W.

[0124] When electrospinning the outer layer: the speed of the receiving device is (2000±100) rpm / min, and the translation speed of the nozzle is (400±50) mm / min.

[0125] (The porosity of the outer layer is about 5%, and the porosity of the inner layer is similar to that of Example 2)

[0126] Comparative Example 1

[0127] A method for preparing a nerve repair catheter, the method comprising:

[0128] (I) Preparation of degradable polyurethane (PU) solution: Same as Example 2.

[0129] (ii) Electrospinning:

[0130] When electrospinning the inner layer: the speed of the receiving device is (500±100) rpm / min, and the translation speed of the nozzle is (100±50) mm / min.

[0131] When electrospinning the outer layer: the speed of the receiving device is (500±100) rpm / min, and the translation speed of the nozzle is (200±50) mm / min.

[0132] In this comparative example, when the rotating speed of the receiving device is lower than 800 rpm / min, the spun sheet produced does not have oriented structural fibers.

[0133] 4. Post-processing: same as Example 2.

[0134] The difference between this comparative example and D1 is that the inner layer and the outer layer of the nerve repair catheter of the present application do not have an oriented fiber structure.

[0135] Comparative Example 2

[0136] A method for preparing a nerve repair catheter, the method comprising:

[0137] (I) Preparation of degradable polyurethane (PU) solution: Same as Example 2.

[0138] (ii) Electrospinning:

[0139] (1)~(6): Same as Example 2.

[0140] (7) The negative voltage is set to (-3±1) KV, and the positive voltage is set to (9±0.5) KV. Start electrospinning and observe the spinning effect until continuous and uniform yarn is ejected. Set the electrospinning time to 30 min to 4 h. Figure 1 A receiving device is used to obtain an electrospun oriented fiber layer.

[0141] 4. Post-processing: same as Example 2.

[0142] The difference between this comparative example and D1 is that it does not include an outer oriented fiber layer.

[0143] Comparative Example 3

[0144] A method for preparing a nerve repair catheter, the method comprising:

[0145] (I) Preparation of degradable polyurethane (PU) solution:

[0146] Same as Example 1.

[0147] (ii) Electrospinning:

[0148] (1)~(8): Same as Example 2.

[0149] (9) In this comparative example, when the outer layer is electrospun, the rotation speed of the receiving device is (500±100) rpm / min, and the translation speed of the nozzle is (200±50) mm / min.

[0150] 4. Post-processing: same as Example 2.

[0151] The difference between this comparative example and D1 is that the exceptional layer in this comparative example does not have an oriented fiber structure.

[0152] Test Example 1

[0153] (I) Mechanical properties test:

[0154] Experimental methods:

[0155] (1) Tensile strength: First, cut the dry sample to be tested into multiple specimens with a width of 10 mm, flat edges, parallel sides and no visible defects. Then turn on the tensile testing machine, set the parameters, perform the tensile strength test, and record the maximum force value at break.

[0156] (2) Elongation at break: First, cut the dry sample to be tested into multiple specimens with appropriate width, flat edges, parallel sides and no visible defects. Then turn on the tensile testing machine, set the parameters, perform the elongation at break test, and process the data; elongation at break (%) = (elongation at break of specimen / original length of specimen) × 100%.

[0157] (3) Suture strength: First, cut the dry sample to be tested into multiple specimens with appropriate width, flat edges, parallel sides and no visible defects. Then, use a suture thread of the selected specification to sew one end of the sample to be tested with two needles and tie a knot to fix it. Suture multiple specimens in the same way, and test the thickness of each sample with a thickness gauge. Then, use a tensile testing machine to clamp the sample to be tested and test the suture strength of the suture to obtain the test data.

[0158] Experimental results:

[0159]

[0160] From the above results, it can be seen that the maximum tensile force of the nerve repair catheter of the present invention reaches more than 50N, the elongation at break reaches more than 600%, and the elastic modulus reaches more than 150Mpa. The nerve repair catheter of the present invention has good mechanical properties and can well meet the mechanical property requirements of the catheter for nerve tissue repair.

[0161] (II) Cell proliferation assay:

[0162] Experimental object: Double-layer oriented fiber layer in the catheter.

[0163] Experimental methods:

[0164] 1. Use a puncher to make a circular sample with the size of the bottom area of ​​a 48-well plate with a double-layer oriented fiber layer. After sterilization, put it into a 48-well cell culture plate and soak it in MEM culture medium containing 10% FBS at 37°C and 60rpm for 24 hours, with the outer layer of the sample facing the bottom of the well.

[0165] 2. The whole process was performed in a clean bench to ensure aseptic operation. Mouse fibroblast L-929 cells grown to the logarithmic growth phase were digested with 0.25% trypsin (containing EDTA). After digestion, the cell suspension was centrifuged (1000 rpm, 5 min), the supernatant was discarded, and the cells were resuspended in MEM medium and counted to obtain 2×10 4 The soaked samples were spread in 48-well plates, and 3 samples were processed in parallel in each group.

[0166] 3. 2×10 4 300 μL of a cell suspension of 10 cells / mL was seeded into each well of a 48-well plate and cultured in a cell culture incubator (37° C., 5% CO 2 , >90% humidity).

[0167] 4. After 24h, 3d and 6d, discard the original culture medium in the 48-well plate, add 30μL of MTT solution (concentration of 5mg / mL) to the corresponding wells of the 48-well plate, and culture in a 37°C, 5% carbon dioxide incubator. After 4h, remove the supernatant, add 200μL of isopropanol to each well to dissolve the crystals. After the crystals are completely dissolved, take out the sample, transfer the liquid in the well to a 96-well plate, 100μL per well, measure the absorbance value at a wavelength of 570nm on an enzyme reader, and compare it with the OD value of the blank group to determine whether the cells have a proliferation effect on the surface of the material and calculate its cell proliferation rate.

[0168] Experimental results:

[0169]

[0170] It can be seen from the above results that the inner layers of Examples 1 and 2 and Comparative Examples 2 and 3 are longitudinally oriented fiber layers, and compared with the non-oriented fiber layer of Comparative Example 1, the cell proliferation effect is better.

[0171] (III) Degradation experiment

[0172] Experimental methods:

[0173] (1) Preparation of enzyme buffer:

[0174] Prepare a solution containing potassium dihydrogen phosphate and disodium hydrogen phosphate with sterile double distilled water, containing 1.653g KH2PO4 and 7.744g NaH2PO4 per liter of buffer. The pH value of the buffer solution should be 7.4±0.2, and PBS solution is added after sterilization. The salts used in the preparation are analytically pure and dried to constant weight.

[0175] (2) Degradation test:

[0176] The sample is vacuum dried at room temperature to constant weight, and the weight of the sample is accurately measured. The sample is placed in a glass container, covered with enzyme buffer and the container is sealed. The minimum volume of the buffer should be 10 mL, and the ratio of the volume of the buffer (mL) to the mass of the sample (g) should be greater than or equal to 30:1. The sample is maintained at 37 ± 1 ° C in a constant temperature water bath or oven.

[0177] (3) Determination of degradation cycle:

[0178] For sample degradation testing, samples were taken at 11 weeks, 16 weeks, 18 weeks, 19 weeks, 34 weeks and 35 weeks for mechanical property testing.

[0179] After wiping the liquid on the sample surface with a paper towel, load the sample into the tensile testing machine fixture and test it directly. The test rate is set to 50mm / min. The test is terminated when the sample cannot be tested for mechanical properties, and the time point for stopping the test is the degradation cycle of the sample.

[0180] Experimental results:

[0181] sample Test cycle / week Example 1 19 Example 2 18 Example 3 34 Comparative Example 1 16 Comparative Example 2 11 Comparative Example 3 16

[0182] From the above results, it can be seen that the nerve repair conduit prepared by the present invention completely degrades within 18 to 34 weeks, which can provide sufficient time and strength support for nerve and tissue repair to meet clinical needs, and the existence time in the body is not too long.

[0183] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nerve repair catheter, characterized in that: The nerve repair conduit is mainly composed of an inner oriented fiber layer and an outer oriented fiber layer; The orientation direction of the oriented fibers in the inner oriented fiber layer is consistent with the axial direction of the nerve repair catheter; The orientation direction of the oriented fibers in the inner oriented fiber layer is different from the orientation direction of the oriented fibers in the outer oriented fiber layer, and the orientation direction forms an angle of 90°±15°.

2. The nerve repair catheter according to claim 1, characterized in that: The diameter of the oriented fibers in the inner oriented fiber layer is 1 nm to 10 μm, and the porosity is 30 to 80%; And / or, the diameter of the oriented fibers in the outer oriented fiber layer is 1 nm to 10 μm, and the porosity is 5 to 20%.

3. The nerve repair catheter according to claim 1, characterized in that: The inner diameter of the nerve repair catheter is 1 to 8 mm, preferably 2 to 6 mm; The thickness of the inner oriented fiber layer is 0.02-0.7 mm, the thickness of the outer oriented fiber layer is 0.03-0.8 mm, and the thickness of the nerve repair conduit is 0.05-1.5 mm.

4. The nerve repair catheter according to claim 1, characterized in that: The oriented fibers are obtained by electrostatic spinning of degradable polyurethane or polylactic acid; Preferably, the weight average molecular weight Mw of the degradable polyurethane is 12W to 16W; Preferably, the weight average molecular weight Mw of the polylactic acid is 15W to 30W.

5. The nerve repair catheter according to claim 1, characterized in that: The maximum tensile force of the nerve repair conduit is 50-100N, the elongation at break is 300-650%, the elastic modulus is 120-165Mpa, and the degradation period is 4-8 months.

6. The nerve repair catheter according to claim 1, characterized in that: The nerve repair catheter further comprises an outer covering layer, which is arranged on the outer oriented fiber layer.

7. A method for preparing a nerve repair catheter according to any one of claims 1 to 6, characterized in that: The preparation method comprises: (A) dissolving a degradable polyurethane in a solvent to obtain a spinning solution, and electrospinning to obtain a fiber orientation sheet A; preparing the fiber orientation sheet A into a tube shape to obtain an intermediate conduit; the orientation direction of the oriented fibers on the inner wall of the intermediate conduit is consistent with the axial direction of the conduit; (B) Electrospinning is performed on the intermediate conduit to form an oriented fiber layer, wherein the orientation direction of the oriented fibers in the oriented fiber layer is at an angle of 90°±15° to the orientation direction of the oriented fibers in the intermediate conduit, and the solvent is removed to obtain a nerve repair conduit having inner and outer oriented fiber layers.

8. The method for preparing a nerve repair catheter according to claim 7, characterized in that: The concentration of the degradable polyurethane in the spinning solution is 5 to 40% (w / v); Preferably, the solvent in the spinning solution is a single solvent of N,N-dimethylformamide, a single solvent of N,N-dimethylacetamide, a mixed solvent of N,N-dimethylformamide and any one or more of tetrahydrofuran, dichloroethane or dimethyl ether, or a mixed solvent of N,N-dimethylacetamide and any one or more of tetrahydrofuran, dichloroethane or dimethyl ether; More preferably, the solvent in the spinning solution is a mixed solvent of N,N-dimethylformamide and tetrahydrofuran, wherein the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 10:1-3:7, wherein the preferred volume ratio is 10:1-1:

1.

9. The method for preparing a nerve repair catheter according to claim 7, characterized in that: The conditions for electrospinning the inner oriented fiber layer include: Negative voltage: -1KV~-4KV, positive voltage: 8KV~10KV, injection speed of nozzle: 0.08-0.7ml / min; rotation speed of receiving device: (1000, 2500)rpm / min; distance between nozzle and receiving device: 0~50mm; translation speed of nozzle is (50, 450)mm / min; The conditions for electrospinning the outer oriented fiber layer include: Negative voltage: -1KV~-4KV, positive voltage: 8KV~10KV, injection speed of the nozzle: 0.08-0.3ml / min; rotation speed of the receiving device: (800, 2000) rpm / min; distance between the nozzle and the receiving device: 0~50mm; translation speed of the nozzle is (0, 250) mm / min.

10. Use of the nerve repair catheter according to any one of claims 1 to 6 in preparing a nerve defect repair body.

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