A pre-stretched hydrogel nerve conduit for promoting directional nerve growth and a preparation method thereof

Abstract

The present invention discloses a pre-stretched hydrogel nerve conduit that promotes directional nerve growth and a preparation method thereof, belonging to the field of preparation of multifunctional hydrogel biomedical materials. The nerve conduit preparation method comprises the following preparation steps: preparing a polyvinyl alcohol solution, adding gelatin to the polyvinyl alcohol solution, stirring to completely dissolve the gelatin in the polyvinyl alcohol solution to prepare a mixed solution, placing the mixed solution in a mold for gelation for a certain period of time, performing cyclic freeze-thaw cross-linking, and then soaking the hydrogel in a sodium chloride / borax solution, and cyclically stretching the hydrogel to obtain a pre-stretched hydrogel nerve conduit. The interior of the pre-stretched hydrogel nerve conduit has a three-dimensional network porous structure, and its interior is a porous structure, which is conducive to the transfer of nutrients and the discharge of metabolic products during the nerve repair process. The surface of the pre-stretched hydrogel nerve conduit has a topological structure that promotes the growth of nerve cells, guiding the directional growth of nerve cells during the repair process. In addition, the pre-stretched hydrogel nerve conduit has excellent biocompatibility and adjustable mechanical properties, and can be used for bridging surgery after peripheral nerve injury. At the same time, it is gradually degraded and absorbed by the body during the nerve regeneration process. The nerve conduit provided by the present invention shows broad application potential in the biomedical field and can effectively promote the repair and regeneration of human tissues such as nerves and blood vessels.

Description

Technical Field

[0001] The present invention relates to the field of preparation of multifunctional hydrogel biomedical materials, and in particular to a pre-stretched hydrogel nerve conduit for promoting directional nerve growth and a preparation method thereof. Background Art

[0002] Peripheral nerve injury (PNI) refers to damage to the structure and function of peripheral nerves caused by trauma, disease, or surgery. Clinical manifestations include paresthesia, muscle weakness, and even paralysis, severely impacting patients' quality of life. PNI is a common and highly prevalent condition, particularly in traffic accidents, work-related injuries, and sports injuries. Although peripheral nerves possess a certain regenerative capacity, post-injury repair still faces numerous obstacles, such as slow nerve fiber regeneration, poor regenerative directionality, and atrophy of the target nerve area.

[0003] Although autologous nerve transplantation is currently the "gold standard" treatment, it is limited by problems such as insufficient donor nerves and loss of donor site function. Alternative technologies such as artificial nerve conduits can act as a bridging chamber between the two stumped nerves, but their clinical effectiveness has not yet met expectations. Therefore, the development of new nerve repair materials with strong biomimetic properties, good biocompatibility, and precise axon guidance functions has become a hot topic and difficulty in peripheral nerve regeneration research. Existing nerve guidance conduits have problems with mechanical properties, biocompatibility, and lack of biomimetic structure.

[0004] When preparing nerve conduits, the topology of their surfaces can be designed through techniques such as 3D printing, electrospinning, or template-based methods to create biomimetic structures that support the directional growth of nerve fibers. However, this method is complex and costly for large-scale production, and requires high standards for both equipment and operators. For clinical applications, a synthetic material that is simple to manufacture, easy to operate, and possesses excellent safety, mechanical properties, and biodegradability, while also possessing the biomimetic structural characteristics of nerve fibers, is desired. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a pre-stretched hydrogel nerve conduit that promotes the directional growth of nerve cells and a preparation method thereof, which can make the neuronal cells grow in a directional manner along the hydrogel topological structure and have both excellent biocompatibility and adjustable mechanical properties. The present invention prepares a hydrogel conduit with suitable mechanical strength, good biocompatibility, and a biomimetic oriented topological structure. The oriented fiber structure is a natural feature inherent in neural tissue, so the hydrogel of the present invention effectively guides the neuronal cells to grow in a directional manner on the surface of the hydrogel nerve conduit. Its adjustable mechanical properties solve the strain problem caused by impact during nerve repair, and conductive polymers such as polypyrrole and graphene can be added to increase conductivity to promote nerve repair.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions.

[0007] The present invention discloses a method for preparing a pre-stretched hydrogel nerve conduit for promoting directional nerve growth, which is characterized by comprising the following steps:

[0008] Prepare a polyvinyl alcohol solution: add polyvinyl alcohol to deionized water according to the mass ratio, stir in a 90°C water bath for 2-4 hours at a stirring speed of 250 rpm / min to completely dissolve the polyvinyl alcohol to obtain a polyvinyl alcohol solution;

[0009] Prepare a mixed solution: add gelatin powder to the above polyvinyl alcohol solution according to the mass ratio, stir in a water bath at 50-60°C for 1-3 hours at a stirring speed of 200-250 rpm / min to completely dissolve the gelatin powder to obtain a mixed solution;

[0010] Preparation of hydrogel: The mixture was poured into a mold and gelled for 1.5 hours, then subjected to three freeze-thaw cycles, with a freezing temperature of -80°C for 8 hours and a melting temperature of 20°C for 2 hours. The mixture was then immersed in a mixed solution of 25 wt% sodium chloride and 0.8 wt% borax for 6 hours.

[0011] Preparation of pre-stretched hydrogel: The hydrogel is subjected to cyclic stretching, with the number of cyclic stretching being 200-500 times, to obtain a pre-stretched hydrogel nerve conduit.

[0012] Furthermore, the mass ratio of the polyvinyl alcohol to deionized water is 10 parts:90 parts, and the mass ratio of the gelatin powder to the polyvinyl alcohol solution is 5 parts:95 parts.

[0013] Furthermore, in the cyclic stretching step, the size of the hydrogel is 10×2×0.1 cm in length, width and height.

[0014] The present invention also discloses a pre-stretched hydrogel nerve conduit for promoting directional nerve growth, characterized in that the nerve conduit is prepared by any of the preparation methods described above.

[0015] Furthermore, the surface of the nerve conduit has a topological structure that promotes the growth of nerve cells, and the diameter of the topological structure is 5 μm-30 μm.

[0016] Furthermore, the nerve conduit has a three-dimensional network porous structure inside, and the pore size of the porous structure is 2 μm-20 μm.

[0017] Furthermore, the pre-stretched hydrogel nerve conduit has no obvious residual strain after 500 cycles of stretching.

[0018] Furthermore, any of the above-mentioned pre-stretched hydrogel nerve conduits for promoting directional nerve growth is used in the preparation of products for repairing peripheral nerve damage.

[0019] Compared with the prior art, the present invention has the following beneficial effects.

[0020] First, the present invention discloses a pre-stretched hydrogel nerve conduit that promotes directional nerve growth. It is prepared using specific raw materials and preparation processes. Due to the mechanical action of pre-stretching, the hydrogel surface forms a unique topological structure with a diameter of 5μm~30μm, which conforms to the bionic characteristics of nerve fibers and helps the adaptive growth of nerve cells.

[0021] The hydrogel has a three-dimensional network porous structure inside, and the pore size of the porous structure is 2μm~20μm, which promotes the transport and exchange of nutrients and metabolic substances.

[0022] The pre-stretched hydrogel has excellent mechanical properties, especially high tensile strength and tensile strain, and can better stretch and deform to adapt to the strain stress at the nerve repair site. When subjected to mechanical force (such as when a mouse is pressed or collided), the hydrogel will not break and can still maintain its original mechanical properties.

[0023] Moreover, due to the addition of borax, [B(OH)4]− ions react with hydroxyl groups on the PVA chains to generate borate groups, forming dynamically reversible ionic crosslinks with excellent fatigue resistance and no obvious residual strain after 500 cycles of stretching.

[0024] While maintaining the good mechanical properties of the hydrogel, the hydrogel has excellent ionic conductivity of 4.6mS / cm, which can conduct electrical signals during the sciatic nerve repair process, further promoting its repair efficiency.

[0025] The present invention provides a pre-stretched hydrogel nerve conduit for promoting directional nerve growth, which has the advantages of simple operation, strong controllability, easy regulation, large-scale preparation and low cost, and can be widely promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a scanning electron microscope photograph of the surface topology of the pre-stretched hydrogel prepared in Example 1 after freeze-drying.

[0027] Figure 2 This is a scanning electron microscope photograph of the cross section of the pre-stretched hydrogel prepared in Example 1 after freeze-drying.

[0028] Figure 3 This is a comparison of the mechanical properties of the pre-stretched hydrogels prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0029] Figure 4 This is a comparison of the ionic conductivity of the pre-stretched hydrogels prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0030] Figure 5 The live / dead cell identification was performed after culturing the RSC96 cell line in the pre-stretched hydrogel extract prepared in Example 1.

[0031] Figure 6 Cytoskeleton immunofluorescence image of PC-12 cells cultured on the surface of the pre-stretched hydrogel with oriented structure prepared in Example 1.

[0032] Figure 7 This is a scanning electron microscope photograph of the surface topology of the pre-stretched hydrogel prepared in Example 2 after freeze-drying.

[0033] Figure 8 This is a scanning electron microscope photograph of the surface topology of the pre-stretched hydrogel prepared in Example 3 after freeze-drying. DETAILED DESCRIPTION

[0034] In order to make the technical solutions, purposes and advantages of the present invention clearer, the present invention will be described in detail below with reference to specific embodiments. It should be noted that the embodiments are only exemplary contents of the present invention and are not restrictive descriptions. Any other implementation methods that can be obtained by those skilled in the art based on the embodiments of the present invention without the need for creative work should be regarded as the scope of protection of the present invention.

[0035] Example 1.

[0036] This embodiment provides a method for preparing a pre-stretched hydrogel, which includes the following steps.

[0037] S1. Preparation of stock solution: Weigh polyvinyl alcohol (G108396 polyvinyl alcohol, pharmaceutical grade, adhesive strength ~240gBloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and deionized water according to the mass ratio of polyvinyl alcohol to deionized water (10 parts by mass:90 parts by mass). Add polyvinyl alcohol to deionized water and stir in a 90°C water bath for 2 h to completely dissolve the polyvinyl alcohol in the deionized water. Stir at 250 rpm / min to prepare a stock solution.

[0038] S2. Preparation of a mixed solution: Weigh gelatin powder according to a mass ratio. The gelatin powder of this example (G776063, gel strength ~240g Bloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and the above-mentioned stock solution are weighed in a ratio of 5 parts by mass to 95 parts by mass. Add the gelatin powder to the above-mentioned stock solution and stir in a 60°C water bath for 1 h to completely dissolve the gelatin powder in the stock solution. The stirring speed is 200 rpm / min to prepare a mixed solution.

[0039] S3. Preparation of hydrogel: The mixed solution was poured into a mold and gelled for 1.5 hours. After three freeze-thaw cycles, the mixture was frozen at -80°C (freezing time was 8 hours) and melted at 20°C (thawing time was 2 hours). The mixture was then immersed in the sodium chloride / borax solution for 6 hours. The concentration of the sodium chloride solution was 25wt%, and the concentration of the borax solution was 0.8wt%.

[0040] S4. Preparation of pre-stretched hydrogel: The hydrogel prepared in S3 was subjected to cyclic stretching with dimensions of 10*2*0.1 cm in length, width and height, and the cyclic stretching was repeated 500 times.

[0041] Microstructure testing:

[0042] Scanning electron microscopy (SEM) was used to characterize the microstructure of the pre-stretched hydrogels. Figure 1 This is a scanning electron microscope image of the surface of the pre-stretched hydrogel after freeze-drying, obtained in step S4 of Example 1. Figure 1 It can be seen from the figure that the surface of the pre-stretched hydrogel has a topological structure that promotes the growth of nerve cells, and the diameter of the topological structure is 5μm~30μm. Figure 2 As shown, the hydrogel has a three-dimensional network porous structure inside, and the pore size of the porous structure is 2μm~20μm.

[0043] Mechanical properties test:

[0044] The pre-stretched hydrogel was subjected to a tensile test using a universal mechanical testing machine. The pre-stretched hydrogel obtained in step S4 of Example 1 was cut to prepare a tensile sample (length and width of 12*4 mm). The thickness before freeze-drying was 1-10 mm and after freeze-drying was 0.1-1 mm. The tensile rate was 100 mm / min. The tensile stress and strain were calculated based on the initial cross-sectional area and initial length of the test sample. The tensile stress-strain curve of the pre-stretched hydrogel of Example 1 was measured as follows: Figure 3 As shown, the tensile strength of the pre-stretched hydrogel of Example 1 was measured to be 3.3 MPa, and the tensile strain was 654.8%. It can be seen that the pre-stretched hydrogel prepared in Example 1 has excellent mechanical properties.

[0045] Ionic conductivity test:

[0046] The conductivity of the pre-stretched hydrogel was tested using an electrochemical workstation. The pre-stretched hydrogel obtained in step S3 of Example 1 was cut to prepare a conductivity test sample (the sample size was 12*4*2 mm in length, width and height). The test sample was connected to the test port of the electrochemical workstation. The transmitted electrical signal can be used to calculate the ionic conductivity of the test sample. The calculation formula is: 𝛿=𝐿 / RS, δ is the ionic conductivity; L is the length of the test sample, S is the cross-sectional area of the test sample; R is the resistance. Figure 4 As shown, the ionic conductivity of the pre-stretched hydrogel of Example 1 was measured to be 4.6 mS / cm. It can be seen that the pre-stretched hydrogel prepared in Example 1 has excellent conductive properties.

[0047] Biocompatibility testing:

[0048] Cell viability was assessed using live / dead cell staining dye (LIVE / DEAD ® Viability / Cytotoxicity Kit, L3224, Invitrogen). Viable cells convert calceinAM into strongly green fluorescent calcein (excitation / emission approximately 495 nm / 515 nm) through esterase activity. EthD-1 only enters cells with damaged membranes and emits red fluorescence (excitation / emission approximately 495 nm / 635 nm) after binding to nucleic acids. This method assesses the life and death status of cells based on these characteristics. The hydrogel prepared in Example 1 was soaked in a 75% ethanol solution for 2 hours, then washed with sterile PBS and sterilized under ultraviolet light for 2 hours. The sterilized hydrogel was added to DMEM complete culture medium at a concentration of 0.1 g / mL and incubated in an incubator at 37°C, 100% relative humidity, and 5% carbon dioxide for 24 hours. RSC96 cells were cultured in the hydrogel extract for 24 hours and then subjected to live / dead cell staining, as shown in FIG. Figure 5 As shown, cells cultured in the gel extract adhered well to the hydrogel surface, most of them were stained green, and the proportion of dead cells was low.

[0049] Cytoskeleton immunofluorescence detection:

[0050] PC12 cells were cultured on the hydrogel surface obtained in Example 1 above under the above cell culture conditions for 24 hours. The cells were fixed and stained with Tuj1 marker (green), and the nuclei were stained with DAPI (blue). The distribution of cells was observed under a confocal microscope. Figure 6 As shown, PC12 grows in an orderly manner along the ultrastructure.

[0051] Example 2 Effect of different stretching times on the material.

[0052] This embodiment provides a method for preparing a pre-stretched hydrogel, which includes the following steps.

[0053] S1. Preparation of stock solution: Weigh polyvinyl alcohol (G108396 polyvinyl alcohol, pharmaceutical grade, adhesive strength ~240g Bloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and deionized water in a mass ratio of 10 parts polyvinyl alcohol to deionized water (90 parts by mass). Add the polyvinyl alcohol to the deionized water and stir in a 90°C water bath for 4 h to completely dissolve the polyvinyl alcohol in the deionized water. Stir at 250 rpm / min to prepare a stock solution.

[0054] S2. Preparation of a mixed solution: Weigh gelatin powder according to a mass ratio. The gelatin powder of this example (G776063, gel strength ~240G BLOOM, Shanghai Aladdin Biochemical Technology Co., Ltd.) and the above-mentioned stock solution are weighed in a ratio of 5 parts by mass to 90 parts by mass. Add the gelatin powder to the above-mentioned stock solution and stir in a 50°C water bath for 3 h to completely dissolve the gelatin powder in the stock solution. The stirring speed is 250 rpm / min to prepare a mixed solution.

[0055] S3. Preparation of hydrogel: The mixed solution was poured into a mold and gelled for 1.5 hours. After three freeze-thaw cycles, the mixture was frozen at -80°C (freezing time was 8 hours) and melted at 20°C (thawing time was 2 hours). The mixture was then immersed in the sodium chloride / borax solution for 6 hours. The concentration of the sodium chloride solution was 25wt%, and the concentration of the borax solution was 0.8wt%.

[0056] S4. Preparation of pre-stretched hydrogel: The hydrogel prepared in S3 was subjected to cyclic stretching with dimensions of 10*2*0.1 cm in length, width and height, and the cyclic stretching was repeated 200 times.

[0057] The pre-stretched hydrogel finally prepared in step S4 of Example 2 was tested using the same testing method as in Example 1. Figure 7 As shown, the surface of the pre-stretched hydrogel finally prepared in step S4 of Example 2 was measured to be a topological structure, but due to insufficient stretching, only a preliminary topological structure was displayed. The tensile strength of the pre-stretched hydrogel of Example 2 was measured to be 3.21 MPa, the tensile strain was 651.4%, and the ion transmission efficiency was 4.3 mS / cm. It can be seen that the pre-stretched hydrogel prepared in Example 2 has adjustable mechanical properties and ion conductivity. However, due to the limitation of the number of stretching cycles, it is difficult to form a parallel topological structure on the surface.

[0058] Example 3 Effect of different stretching times on the material.

[0059] This embodiment provides a method for preparing a pre-stretched hydrogel, which includes the following steps.

[0060] S1. Preparation of stock solution: Weigh polyvinyl alcohol (G108396 polyvinyl alcohol, pharmaceutical grade, adhesive strength ~240gBloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and deionized water according to the mass ratio of polyvinyl alcohol to deionized water (10 parts by mass:90 parts by mass). Add polyvinyl alcohol to deionized water and stir in a 90°C water bath for 4 h to completely dissolve the polyvinyl alcohol in the deionized water. Stir at 250 rpm / min to prepare a stock solution.

[0061] S2. Preparation of a mixed solution: Weigh gelatin powder according to a mass ratio. The gelatin powder of this example (G776063, gel strength ~240G BLOOM, Shanghai Aladdin Biochemical Technology Co., Ltd.) and the above-mentioned stock solution are weighed in a ratio of 5 parts by mass to 90 parts by mass. Add the gelatin powder to the above-mentioned stock solution and stir in a 50°C water bath for 3 h to completely dissolve the gelatin powder in the stock solution. The stirring speed is 250 rpm / min to prepare a mixed solution.

[0062] S3. Preparation of hydrogel: The mixed solution was poured into a mold and gelled for 1.5 hours. After three freeze-thaw cycles, the mixture was frozen at -80°C (freezing time was 8 hours) and melted at 20°C (thawing time was 2 hours). The mixture was then immersed in the sodium chloride / borax solution for 6 hours. The concentration of the sodium chloride solution was 25wt%, and the concentration of the borax solution was 0.8wt%.

[0063] S4. Preparation of pre-stretched hydrogel: The hydrogel prepared in S3 was subjected to cyclic stretching, with dimensions of 10*2*0.1 cm in length, width and height, and 0 cyclic stretching times.

[0064] The pre-stretched hydrogel finally prepared in step S4 of Example 3 was tested using the same testing method as in Example 1. Figure 8 The hydrogel prepared in step S4 of Example 3 was found to have a substantially smooth surface. The pre-stretched hydrogel of Example 3 exhibited a tensile strength of 3.33 MPa, a tensile strain of 654.9%, and an ion transmission efficiency of 4.1 mS / cm. This indicates that the pre-stretched hydrogel prepared in Example 3 exhibits adjustable mechanical properties and ionic conductivity. Similarly, due to the limited number of stretching cycles, it was difficult to form a parallel topological structure on the surface.

[0065] Comparative Example 1.

[0066] S1. Preparation of stock solution: Weigh polyvinyl alcohol (G108396 polyvinyl alcohol, pharmaceutical grade, adhesive strength ~240g Bloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and deionized water in a mass ratio of 10 parts polyvinyl alcohol to deionized water (90 parts by mass). Add the polyvinyl alcohol to the deionized water and stir in a 90°C water bath for 4 h to completely dissolve the polyvinyl alcohol in the deionized water. Stir at 250 rpm / min to prepare a stock solution.

[0067] S2. Preparation of a mixed solution: Weigh the collagen powder according to the mass ratio. The collagen powder of this comparative example (C835547, Shanghai Aladdin Biochemical Technology Co., Ltd.) and the above-mentioned stock solution are in a mass ratio of 5 parts:90 parts. Add the collagen powder to the above-mentioned stock solution and stir in a 50°C water bath for 3 h to completely dissolve the collagen powder in the stock solution. The stirring speed is 250 rpm / min to prepare a mixed solution.

[0068] S3. Preparation of hydrogel: The mixed solution was poured into a mold and gelled for 1.5 hours. After three freeze-thaw cycles, the mixture was frozen at -80°C (freezing time was 8 hours) and melted at 20°C (thawing time was 2 hours). The mixture was then immersed in the sodium chloride / borax solution for 6 hours. The concentration of the sodium chloride solution was 10wt%, and the concentration of the borax solution was 0.8wt%.

[0069] S4. Preparation of pre-stretched hydrogel: The hydrogel prepared in S3 was subjected to cyclic stretching with dimensions of 10*2*0.1 cm in length, width and height, and the cyclic stretching was repeated 5 times.

[0070] The pre-stretched hydrogel prepared in step S4 of Comparative Example 1 was tested using the same testing method as in Example 1. The pre-stretched hydrogel prepared in step S4 of Comparative Example 1 was found to have a substantially smooth surface. The pre-stretched hydrogel of Comparative Example 1 had a tensile strength of 1.49 MPa, a tensile strain of 818.9%, an ion transmission efficiency of 2.5 mS / cm, and no apparent topological structure was observed on the surface.

[0071] Comparative Example 2.

[0072] S1. Stock Solution Preparation: Weigh polyvinyl alcohol (G108396 polyvinyl alcohol, pharmaceutical grade, adhesive strength ~240g Bloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and deionized water in a mass ratio of 10 parts polyvinyl alcohol to 90 parts deionized water. Add the polyvinyl alcohol to the deionized water and stir in a 90°C water bath for 4 h to completely dissolve the polyvinyl alcohol in the deionized water. Stir at 250 rpm / min to prepare a stock solution.

[0073] S2. Preparation of a mixed solution: Weigh gelatin powder, sodium alginate powder (S817374, Shanghai Aladdin Biochemical Technology Co., Ltd.) of this comparative example, and the above-mentioned stock solution in a mass ratio of 5 parts:90 parts. Add the sodium alginate powder to the above-mentioned stock solution and stir in a 50°C water bath for 3 h to completely dissolve the sodium alginate powder in the stock solution. Stir at a speed of 250 rpm / min to prepare a mixed solution.

[0074] S3. Preparation of hydrogel: The mixed solution was poured into a mold and gelled for 1.5 hours. After three freeze-thaw cycles, the mixture was frozen at -80°C (freezing time was 8 hours) and melted at 20°C (thawing time was 2 hours). The mixture was then immersed in the sodium chloride / borax solution for 6 hours. The concentration of the sodium chloride solution was 8wt%, and the concentration of the borax solution was 0.6wt%.

[0075] S4. Preparation of pre-stretched hydrogel: The hydrogel prepared in S3 was subjected to cyclic stretching with dimensions of 10*2*0.1 cm in length, width and height, and the cyclic stretching was repeated 500 times.

[0076] The pre-stretched hydrogel prepared in step S4 of Comparative Example 2 was tested using the same testing method as in Example 1. The pre-stretched hydrogel prepared in step S4 of Comparative Example 2 exhibited a topological surface structure with a diameter ranging from 5 μm to 30 μm. The tensile strength of the pre-stretched hydrogel in Comparative Example 2 was measured to be 1.17 MPa, the tensile strain was 856.4%, and the ion transmission efficiency was 2.3 mS / cm. Under sufficient stretching conditions, Comparative Example 2 formed a unique surface topography that facilitated the oriented growth of cells.

[0077] Comparative Example 3.

[0078] S1. Stock Solution Preparation: Weigh polyvinyl alcohol (G108396 polyvinyl alcohol, pharmaceutical grade, adhesive strength ~240g Bloom, Shanghai Aladdin Biochemical Technology Co., Ltd.) and deionized water in a mass ratio of 10 parts polyvinyl alcohol to 90 parts deionized water. Add the polyvinyl alcohol to the deionized water and stir in a 90°C water bath for 4 h to completely dissolve the polyvinyl alcohol in the deionized water. Stir at 250 rpm / min to prepare a stock solution.

[0079] S2. Preparation of a mixed solution: Weigh xanthan gum powder, the xanthan gum powder of this comparative example (G810381, Shanghai Aladdin Biochemical Technology Co., Ltd.), and the above-mentioned stock solution in a mass ratio of 1 part:100 parts. Add the xanthan gum powder to the above-mentioned stock solution and stir in a 60°C water bath for 4 h to completely dissolve the xanthan gum powder in the stock solution at 250 rpm / min to prepare a mixed solution.

[0080] S3. Preparation of hydrogel: The mixed solution was poured into a mold and gelled for 1.5 hours. After three freeze-thaw cycles, the mixture was frozen at -60°C (freezing time was 8 hours) and melted at 30°C (thawing time was 1.5 hours). The mixture was then immersed in the sodium chloride / borax solution for 2.5 hours. The concentration of the sodium chloride solution was 6wt%, and the concentration of the borax solution was 0.4wt%.

[0081] S4. Preparation of pre-stretched hydrogel: The hydrogel prepared in S3 was subjected to cyclic stretching with dimensions of 10*2*0.1 cm in length, width and height, and the cyclic stretching was repeated 400 times.

[0082] The pre-stretched hydrogel prepared in step S4 of Comparative Example 3 was tested using the same testing method as in Example 1. The pre-stretched hydrogel prepared in step S4 of Comparative Example 3 exhibited a topological surface structure with a diameter ranging from 2 μm to 30 μm. The tensile strength of the pre-stretched hydrogel in Comparative Example 3 was measured to be 0.91 MPa, the tensile strain was 528.2%, and the ion transmission efficiency was 1.6 mS / cm. Under sufficient stretching conditions, Comparative Example 3 formed a unique surface morphology that facilitated the oriented growth of cells.

[0083] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, they can make improvements or changes based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to this application.

[0084] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a pre-stretched hydrogel nerve conduit for promoting directional nerve growth, characterized in that: The following steps are involved: Prepare a polyvinyl alcohol solution: add polyvinyl alcohol to deionized water according to the mass ratio, stir in a 90°C water bath for 2-4 hours at a stirring speed of 250 rpm to completely dissolve the polyvinyl alcohol to obtain a polyvinyl alcohol solution; Prepare a mixed solution: add gelatin powder to the above polyvinyl alcohol solution according to the mass ratio, stir in a water bath at 50-60°C for 1-3 hours at a stirring speed of 200-250 rpm to completely dissolve the gelatin powder to obtain a mixed solution; Preparation of hydrogel: The mixture was poured into a mold and gelled for 1.5 hours, then subjected to three freeze-thaw cycles, with a freezing temperature of -80°C for 8 hours and a melting temperature of 20°C for 2 hours. The mixture was then immersed in a mixed solution of 25 wt% sodium chloride and 0.8 wt% borax for 6 hours. Preparation of pre-stretched hydrogel: The hydrogel is subjected to cyclic stretching for 200-500 times to obtain a pre-stretched hydrogel nerve conduit; The mass ratio of polyvinyl alcohol to deionized water in the polyvinyl alcohol solution is 10 parts:90 parts, and the mass ratio of gelatin powder to polyvinyl alcohol solution in the mixed solution is 5 parts:95 parts; The surface of the pre-stretched hydrogel nerve conduit has a topological structure that promotes the growth of nerve cells, and the diameter of the topological structure is 5 μm-30 μm.

2. The method for preparing a pre-stretched hydrogel nerve conduit for promoting directional nerve growth according to claim 1, characterized in that: During the cyclic stretching step described in the preparation of pre-stretched hydrogels, the dimensions of the hydrogels were 10×2×0.1 cm in length, width, and height.

3. A pre-stretched hydrogel nerve conduit for promoting directional nerve growth, characterized in that: The nerve conduit is prepared by the preparation method according to any one of claims 1-2.

4. The pre-stretched hydrogel nerve conduit for promoting directional nerve growth according to claim 3, characterized in that: The pre-stretched hydrogel nerve conduit has a three-dimensional network porous structure inside, and the pore size of the porous structure is 2 μm-20 μm.

5. The pre-stretched hydrogel nerve conduit for promoting directional nerve growth according to claim 3, characterized in that: The pre-stretched hydrogel nerve conduit has no obvious residual strain after 500 cycles of stretching.

6. Use of the pre-stretched hydrogel nerve conduit for promoting directional nerve growth according to any one of claims 3 to 5 in the preparation of a product for repairing peripheral nerve damage.

Images