Paper fiber-based bone repair scaffold as well as preparation method and application thereof

Abstract

The invention relates to a paper fiber-based bone repair scaffold which is made of hydroxyapatite, polyvinyl alcohol and paper fibers, and the paper fibers are wide in source and low in cost; hydroxyapatite has good biocompatibility and osteoconductivity, polyvinyl alcohol serving as an adhesive has good biocompatibility and degradability, and the mechanical supporting capacity of the bone repair scaffold can be improved; the invention relates to a preparation method of a paper fiber-based bone repair scaffold. The preparation method is convenient to operate. The invention also relates to application of the paper fiber-based bone repair scaffold in preparation of a bone repair material, and tests prove that the paper fiber-based bone repair scaffold prepared by the preparation method disclosed by the invention is good in swelling property and free of structural collapse and damage, and the mechanical property meets the requirements; the paper fiber-based bone repair scaffold has no cytotoxicity and good biocompatibility, and can promote proliferation, adhesion and migration of BMSC cells; animal experiments prove that the paper fiber based bone repair scaffold has a better bone repair effect and a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of bone repair scaffold technology, and particularly relates to a paper fiber-based bone repair scaffold, its preparation method, and its application. Background Technology

[0002] Bone defects refer to structural gaps or interruptions in bone structure caused by various factors. Their formation is complex and diverse, potentially stemming from direct external trauma that disrupts bone integrity, or from the progressive erosion of bone tissue by disease, infection, or metabolic abnormalities. From a traumatic perspective, comminuted fractures or open fractures caused by high-energy injuries are often accompanied by bone fragment loss or displacement. Infections, insufficient blood supply, or improper fixation during fracture healing can also lead to bone defects. Infectious diseases such as osteomyelitis or bone tuberculosis continuously destroy bone, forming necrotic cavities; bone tumors or metabolic bone diseases (such as severe osteoporosis) indirectly cause pathological defects through abnormal proliferation or decreased bone density. Furthermore, iatrogenic factors such as tumor resection surgery or radiation-induced osteonecrosis, as well as congenital skeletal developmental abnormalities, can all contribute to bone defects. These causes share the commonality of disrupting the physiological structure and mechanical support function of the bone, thereby affecting normal bodily functions and even threatening life and health.

[0003] The necessity of repairing bone defects stems from their profound impact on bodily function and overall health. The core goal of bone defect repair is to restore the continuity, mechanical stability, and physiological function of the skeleton. Reconstructing defects through bone grafting, bone transport techniques, or biomaterial filling not only prevents the worsening of deformities but also provides mechanical protection for surrounding tissues and promotes the functional recovery of muscles, nerves, and blood vessels. For example, repairing spinal bone defects can prevent the risk of paralysis caused by spinal cord compression, while repairing periarticular defects helps restore motor function. Simultaneously, the repair process stimulates local osteogenic activity, restores blood circulation, and creates a favorable environment for bone self-repair. From a quality-of-life perspective, timely repair can significantly reduce the psychological burden caused by functional impairment, helping patients return to a normal life. Therefore, developing personalized repair plans based on different causes and defect characteristics is not only a reflection of medical technology but also a practical guarantee of patients' dignity and health rights.

[0004] In the field of bone defect repair scaffolds, hydroxyapatite (HAp) is one of the most widely used materials. Firstly, because the chemical composition of HAp is highly similar to the inorganic components of human bone (containing calcium and phosphorus), it can directly promote osteocyte adhesion, proliferation, and new bone formation, giving the bone defect repair scaffold good biocompatibility and osteoconductivity. Secondly, the surface of HAp is rich in hydroxyl and phosphate groups, which can adsorb calcium and phosphorus ions in the blood, inducing bone-like apatite deposition, thereby enhancing the integration of the scaffold with the host bone and thus enhancing the mechanical stability of the scaffold. Finally, HAp is often combined with other materials (such as PLGA, chitosan, and conductive polymers) to compensate for the shortcomings of single materials and achieve synergistic repair through osteogenic and vascularization processes. However, current methods for preparing bone defect repair scaffolds are cumbersome and use a wide variety of raw materials, leading to increased costs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a paper fiber-based bone repair scaffold, its preparation method, and its application.

[0006] The technical solution of this invention is as follows: A paper fiber-based bone repair scaffold comprises, by weight: 7-14 parts hydroxyapatite, 20-30 parts polyvinyl alcohol, and 1-3 parts paper fiber.

[0007] Furthermore, the paper fiber is prepared by pretreating paper scraps with sodium hydroxide solution and sodium hypochlorite solution to obtain paper fiber.

[0008] Further, the specific steps of the pretreatment are as follows: paper scraps are added to a 3-8 wt% sodium hydroxide solution and mixed and stirred for 3-5 hours to obtain a mixture A; then 2-4 wt% hypochlorous acid solution is added to mixture A, the pH is adjusted to 4-5 with 1M nitric acid solution, and the mixture is mixed and stirred for 2-4 hours. After filtration, rinsing and drying, paper fibers are obtained.

[0009] Furthermore, the hydroxyapatite has a particle size of 50-70 nm.

[0010] A method for preparing a paper fiber-based bone repair scaffold includes the following steps: dispersing paper fibers in a polyvinyl alcohol solution to obtain a viscous mixture of paper fibers; adding hydroxyapatite to the viscous mixture of paper fibers and stirring to obtain a viscoelastic gel; and freeze-drying the viscoelastic gel to obtain a paper fiber-based bone repair scaffold.

[0011] Furthermore, the process parameters for dispersing the paper fibers in a polyvinyl alcohol solution to obtain a viscous paper fiber mixture are as follows: stirring at 2000-3000 r / min at 80-95℃ for 20-30 h to obtain the viscous paper fiber mixture.

[0012] Furthermore, the process parameters for adding hydroxyapatite to the viscous mixture of paper fibers and stirring to obtain a viscoelastic gel are as follows: stirring at 2000-3000 r / min at 80-95℃ for 3-5 hours to obtain a viscoelastic gel.

[0013] The application of the paper fiber-based bone repair scaffold in the preparation of bone repair materials.

[0014] Compared with the prior art, the present invention has at least the following advantages: 1. This invention relates to a paper fiber-based bone repair scaffold, wherein the scaffold is made of hydroxyapatite, polyvinyl alcohol, and paper fiber. Paper fiber is widely available, low in cost, and has the advantages of being modifiable and having a controllable structure. Hydroxyapatite has good biocompatibility and osteoconductivity, and polyvinyl alcohol, as a binder, has good biocompatibility and biodegradability, and can improve the mechanical support capacity of the bone repair scaffold. The combination of the three materials improves the mechanical strength of the bone repair scaffold.

[0015] 2. This invention relates to a method for preparing a paper fiber-based bone repair scaffold. The method first disperses paper fibers in a polyvinyl alcohol solution to obtain a viscous mixture of paper fibers. Hydroxyapatite is added to the viscous mixture of paper fibers and stirred to obtain a viscoelastic gel. The viscoelastic gel is then freeze-dried to obtain the paper fiber-based bone repair scaffold. The steps are simple and the operation is convenient.

[0016] 3. This invention relates to the application of paper fiber-based bone repair scaffolds in the preparation of bone repair materials. Experiments have shown that the paper fiber-based bone repair scaffolds prepared by the method described in this invention exhibit good swelling properties, without structural collapse or damage; and the mechanical properties of the bone repair scaffolds meet the requirements. Cell adhesion and viability experiments have demonstrated that the paper fiber-based bone repair scaffolds prepared by this invention are non-cytotoxic, have good biocompatibility, and can promote the proliferation, adhesion, and migration of BMSC cells, with the migration direction of BMSC cells consistent with the orientation of the paper fibers. Animal experiments have confirmed that the paper fiber-based bone repair scaffolds have good bone repair effects and broad application prospects. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0018] Figure 1 This is a test diagram of the swelling performance of the freeze-dried stent in Test Example 1 of the present invention; Figure 2 The image and stress-strain curve of the freeze-dried support after 50% compression are shown in Test Example 2 of this invention. Figure 3 This is an optical photograph of paper fibers and mesenchymal stem cells co-cultured for 24 hours in Test Example 3 of this invention. Figure 4 This is Example 3 of the test for the co-culture of mesenchymal stem cells and freeze-dried scaffolds in the present invention, showing cell adhesion and viability. Figure 5 Optical photographs and Micro-CT images of a rat femoral lateral bone defect model after 8 weeks, as an application example of this invention. Detailed Implementation

[0019] The present invention will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0020] This invention provides a general and / or specific description of the materials and experimental methods used in the experiments. Unless otherwise specified, all experimental or testing methods are conventional methods; all reagents or instruments used, unless otherwise specified, are commercially available conventional products prepared or used using conventional methods.

[0021] Source of materials: Paper fiber: Purchased from Tianzhang Paper Products A4 printing paper; Hydroxyapatite: Particle size 50-70 nm; All other reagents were of analytical grade.

[0022] Experimental methods 1. Mechanical property testing: Mechanical testing shall be conducted in accordance with the compression method specified in GB / T 7314-2017.

[0023] 2. Cytotoxicity test: Cytotoxicity of the samples was observed using an inverted fluorescence microscope in accordance with standard cell culture methods.

[0024] 3. Cell adhesion and cell viability test: Using a confocal microscope, the viability and adhesion of cells on the scaffold and cells were observed according to the standard cell viability staining method.

[0025] 4. Evaluation of the effect of scaffold material on repair of femoral end defects in rats: The repair effect of scaffold material on femoral end bone defects in rats was observed using optical cameras and Micro-CT.

[0026] Example 1 This embodiment describes a method for preparing a paper fiber-based bone repair scaffold, comprising the following steps: S1. Tear the printing paper into small paper scraps. Put 5g of paper scraps into 2L of pure water, stir and wash at 1200r / min for 1h, vacuum filter (500mL sand core filter), rinse and dry at 80℃ for 20h to obtain dried initial paper scraps. Disperse 2g of dried paper scraps in 40mL of 5% sodium hydroxide solution, stir at 1200r / min at 80℃ for 3h, then add 100mL of 2wt% hypochlorous acid solution, adjust the pH to 4 with 1M nitric acid solution, heat to 100℃, stir continuously at 800r / min for 2h, vacuum filter (500mL sand core filter), filter and dry at 80℃ for 10h to obtain paper fibers. S2. Take 1g of the paper fiber obtained in step S1 and disperse it in 100mL of 20% polyvinyl alcohol solution. Stir continuously at 2500r / min at 90℃ for 24h to obtain a viscous paper fiber mixed solution. Then add 7g of nano hydroxyapatite and continue stirring at 2500r / min for 4h. After stirring, a viscoelastic mixture is obtained. S3. The viscoelastic mixture obtained in step S2 is injected into the desired mold and frozen in a -20°C freezer for 12 hours. Then, it is freeze-dried in a freeze dryer (-86°C, 0.16mba) for 10 hours to obtain a freeze-dried support. The freeze-dried support prepared by the method of this embodiment has a hydroxyapatite content of 25%.

[0027] Example 2 This embodiment describes a method for preparing a paper fiber-based bone repair scaffold, comprising the following steps: S1. Tear the printing paper into small paper scraps. Put 5g of paper scraps into 2L of pure water, stir and wash for 1h at 1200r / min, vacuum filter (500mL sand core filter), rinse and dry at 80℃ for 20h to obtain dried initial paper scraps. Disperse 2g of dried paper scraps in 40mL of 3% sodium hydroxide solution, stir at 1200r / min for 3h at 80℃, then add 100mL of 3wt% hypochlorous acid solution, adjust the pH to 4 with 1M nitric acid solution, heat to 100℃, stir continuously at 800r / min for 3h, vacuum filter (500mL sand core filter) and dry at 80℃ for 10h to obtain paper fibers. S2. Take 2g of the paper fiber obtained in step S1 and disperse it in 100mL of 25% polyvinyl alcohol solution. Stir continuously at 2000r / min at 90℃ for 24h to obtain a viscous paper fiber mixed solution. Then add 10g of nano hydroxyapatite and continue stirring at 3000r / min for 4h. After stirring, a viscoelastic mixture is obtained. S3. The viscoelastic mixture obtained in step S2 is injected into the desired mold and frozen in a -20°C freezer for 12 hours. Then, it is freeze-dried in a freeze dryer (-86°C, 0.16 mba) for 10 hours to obtain a freeze-dried support. The freeze-dried support prepared by the method of this embodiment has a hydroxyapatite content of 27%.

[0028] Example 3 This embodiment describes a method for preparing a paper fiber-based bone repair scaffold, comprising the following steps: S1. Tear the printing paper into small paper scraps. Put 5g of paper scraps into 2L of pure water, stir and wash for 1h at 1200r / min, vacuum filter (500mL sand core filter), rinse and dry at 80℃ for 20h to obtain dried initial paper scraps. Disperse 2g of dried paper scraps in 40mL of 6% sodium hydroxide solution, stir at 1200r / min for 3h at 80℃, then add 100mL of 4wt% hypochlorous acid solution, adjust the pH to 4.5 with 1M nitric acid solution, heat to 100℃, stir continuously at 800r / min for 2.5h, vacuum filter (500mL sand core filter) and dry at 80℃ for 10h to obtain paper fibers. S2. Take 1g of the paper fiber obtained in step S1 and disperse it in 100mL of 30% polyvinyl alcohol solution. Stir continuously at 2800r / min at 85℃ for 24h to obtain a viscous paper fiber mixed solution. Then add 14g of nano hydroxyapatite and continue stirring at 3000r / min for 4h. After stirring, a viscoelastic mixture is obtained. S3. The viscoelastic mixture obtained in step S2 is injected into the desired mold and frozen in a -20°C freezer for 12 hours. Then, it is freeze-dried in a freeze dryer (-86°C, 0.16 mba) for 10 hours to obtain a freeze-dried support. The freeze-dried support prepared by the method of this embodiment has a hydroxyapatite content of 31%.

[0029] Test Example 1: Swelling Performance Test This test example uses the freeze-dried stent prepared in Example 1 to test its swelling performance and stability in solution.

[0030] The obtained scaffolds were cut into cylinders with a height of 10 mm and placed into 12-well cell culture plates. 1.5 ml of PBS buffer was added to each well, and the plates were incubated at 37°C with shaking for 24 hours. The swelling properties of the bone repair scaffolds were observed. Figure 1 A, Figure 1 B represents the freeze-dried scaffold before and after soaking. The figure shows that the bone scaffold after soaking did not have obvious structural collapse or damage, and the solution became turbid, indicating that hydroxyapatite leached out, which can promote bone repair.

[0031] Test Example 2: Mechanical Property Testing This test example uses the freeze-dried support obtained in Example 1 to test its mechanical properties.

[0032] The obtained support was cut into cylinders with a height of 10 mm. Compression tests were conducted using a materials mechanics testing machine according to the national standard GB / T 7314-2017. The compression rate was 10 cm / min, and the test was stopped when the compressive strain reached 50%. Three parallel samples were tested for each group. The image of the support after 50% compression strain is shown in the figure. Figure 2 As shown in A, Figure 2 B is the stress-strain curve, showing that the compressive stress of the lyophilized scaffold with 25% hydroxyapatite at 50% strain is 1.72 MPa, indicating that the lyophilized scaffold prepared by the method of this invention can induce BMSC cell migration and proliferation and promote bone repair.

[0033] Test Example 3: Cytotoxicity Test 1. Taking the paper fibers prepared in step S1 of Example 1 as an example, cytotoxicity was tested. The paper fibers were sterilized at 120°C under high temperature and pressure for 30 min, then cooled to room temperature and pressure and dried. Under aseptic conditions, 0.5*0.5 cm of sterilized paper fibers were seeded into 24-well plates, with three replicates. 200 μL of rat BMSC cell suspension was added to each well, with a cell density of 1×10⁻⁶ cells / well. 5 / well, in which rat BMSC cells were P1 generation cells, were co-cultured at 37℃ and 5% CO2 concentration for 24 h, and cell growth was observed and photographed using an inverted microscope. The results are as follows: Figure 3 As shown in the figure, the cells have normal morphology and adhere to the wall without obvious dead cells floating, indicating that the paper fibers have no obvious cytotoxicity.

[0034] 2. Taking the lyophilized scaffold prepared in Example 1 as an example, cell adhesion and cell viability were tested. The lyophilized scaffold and rat BMSC cells were co-cultured at 37°C and 5% carbon dioxide for 24 hours. After co-culturing, the scaffold was stained with a cell viability staining agent for 30 minutes, followed by confocal fluorescence imaging. The results are as follows: Figure 4 As shown in the figure, BMSCs adhere to the fibrous scaffold and are aligned with the paper fibers, with no obvious dead cells. This further indicates that the scaffold has good cell compatibility and can promote the proliferation, adhesion, and migration of BMSCs.

[0035] Application examples This application example uses the freeze-dried stent prepared in Example 1 to test its repair effect.

[0036] A paper fiber composite scaffold was implanted into an 8-week-old anesthetized rat model of lateral femoral bone defect. After 8 weeks of unrestrained rearing, the rats were sacrificed, and the femur was harvested to observe bone healing. Figure 5As shown. After Micro-CT testing and 3D reconstruction, the repair effect and new bone growth were observed. Figure 5 The results show that the scaffold has a good repair effect in a rat bone defect model and can be used as a new bone defect repair material.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions 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, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A paper fiber-based bone repair scaffold, characterized in that, By weight, it includes: 7-14 parts hydroxyapatite, 20-30 parts polyvinyl alcohol, and 1-3 parts paper fiber.

2. The paper fiber-based bone repair scaffold according to claim 1, characterized in that, The paper fiber is prepared by pretreating paper scraps with sodium hydroxide solution and sodium hypochlorite solution to obtain paper fiber.

3. The paper fiber-based bone repair scaffold according to claim 2, characterized in that, The specific steps of the pretreatment are as follows: add paper scraps to a 3-8 wt% sodium hydroxide solution, mix and stir for 3-5 hours to obtain mixture A; then add 2-4 wt% hypochlorous acid solution to mixture A, adjust the pH to 4-5 with 1M nitric acid solution, mix and stir for 2-4 hours, then filter, rinse and dry to obtain paper fibers.

4. The paper fiber-based bone repair scaffold according to claim 3, characterized in that, The hydroxyapatite has a particle size of 50-70 nm.

5. A method for preparing a paper fiber-based bone repair scaffold according to any one of claims 1-4, characterized in that, The process includes the following steps: dispersing paper fibers in a polyvinyl alcohol solution to obtain a viscous mixture of paper fibers; adding hydroxyapatite to the viscous mixture of paper fibers and stirring to obtain a viscoelastic gel; and freeze-drying the viscoelastic gel to obtain a paper fiber-based bone repair scaffold.

6. The preparation method according to claim 5, characterized in that, The process parameters for dispersing paper fibers in a polyvinyl alcohol solution to obtain a viscous paper fiber mixture are as follows: stirring at 2000-3000 r / min for 20-30 h at 80-95℃ to obtain the viscous paper fiber mixture.

7. The preparation method according to claim 6, characterized in that, The process parameters for adding hydroxyapatite to the viscous mixture of paper fibers and stirring to obtain a viscoelastic gel are as follows: stirring at 2000-3000 r / min at 80-95℃ for 3-5 hours to obtain a viscoelastic gel.

8. The use of the paper fiber-based bone repair scaffold according to any one of claims 1-4 in the preparation of bone repair materials.

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