A 3D printed bone repair material and preparation method thereof

Abstract

The present invention belongs to the technical field of medical materials, and specifically provides a 3D printed bone repair material and a preparation method thereof. The 3D printed bone repair material is prepared from PCL / MnO2 composite microspheres and SiN. PCL has good biocompatibility and biodegradability. The addition of SiN enhances the mechanical properties and osteoinductive properties of the 3D printed bone repair material, improves the overall degradation rate, provides necessary space for new bone formation, and is beneficial to calcium deposition. And MnO2 can release oxygen and manganese ions, and the manganese ions can promote calcium deposition, jointly promoting cell infiltration, osteogenic differentiation and matrix mineralization, promoting the proliferation of bone precursor cells, accelerating bone defect repair, promoting bone regeneration. The 3D printed bone repair material prepared by the present invention has good mechanical properties, biocompatibility, antibacterial property and biodegradability, promotes cell proliferation, and accelerates bone repair and bone regeneration.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical materials, and specifically provides a 3D printed bone repair material and a preparation method thereof. Background Art

[0002] Bone defect is a common disease caused by a variety of factors, including impact trauma, tumors, and inflammatory infections. Bone transplant materials include autologous transplants, allogeneic transplants, and xenografts. As the "gold standard" for treating bone defects, autologous bone transplants can be divided into vascularized bone transplants and non-vascularized bone transplants. Autologous bone transplants have the advantages of biocompatibility, good osteogenesis, and no risk of disease transmission. However, due to unfavorable conditions such as limited material sources, long treatment cycles, and secondary injuries, autologous bone transplants are often used to treat short-segment bone defects and the treatment effect may be unsatisfactory. Although allogeneic bone transplants have many sources, they often have defects such as immune rejection, potential disease transmission, and structural property damage. Therefore, a substance that can replace bone transplants is needed, which has the characteristics of superior source, safety, stability, and osteoinductivity to traditional transplanted bones, and is gradually used as a substitute for bone transplants.

[0003] The maturity of 3D printing technology provides more advanced technical means for the construction of material scaffolds in bone tissue engineering. The three-dimensional motion platform with precise three-axis or even multi-axis control makes it a layer-by-layer additive manufacturing process. Through the selection of different equipment and the adjustment of process parameters, multiple physical and chemical properties and spatial configurations of material scaffolds can be controlled.

[0004] At present, some metal materials, bioceramics, and inorganic composite materials have entered the clinic. These materials often focus on the strength and durability of the finished stent and can only meet the most basic biocompatibility. There are still many problems: it is difficult for the prosthesis to take into account both mechanical properties and porosity; the degradation rate is uncontrollable; the precision is poor and lacks personalization; the antibacterial properties are insufficient and the infection rate is high. In addition, the preparation of bone tissue prostheses involves multiple interdisciplinary disciplines and is technically difficult, so breakthroughs are needed. Summary of the invention

[0005] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a 3D printed bone repair material and a preparation method thereof. The 3D printed bone repair material prepared by the present invention includes PCL / MnO2 composite microspheres and SiN. PCL has good biocompatibility and biodegradability, SiN has good mechanical properties, and exhibits enhanced osteogenicity, hardness and antibacterial properties. PCL and SiN are combined to form a dense structure, which improves the mechanical properties of the composite material and meets the mechanical strength requirements of bone implant substitute materials. SiN is conducive to calcium deposition and promotes the expression of osteogenic proteins. PCL is compounded with MnO2, and MnO2 releases oxygen and Mn 2+, together with SiN, promotes calcium deposition, promotes bone regeneration, and accelerates bone healing. The 3D printed bone repair material prepared by the present invention has good mechanical properties, biocompatibility, antibacterial properties, and biodegradability, promotes cell proliferation, and accelerates bone repair and bone regeneration.

[0006] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0007] The present invention provides a 3D printing bone repair material, which is prepared from the following raw materials in parts by weight: 60-90 parts of PCL (polycaprolactone) / MnO2 composite microspheres and 26-40 parts of SiN.

[0008] The present invention also provides a method for preparing a 3D printed bone repair material, which specifically comprises the following steps:

[0009] S1: Take 60-90 parts of PCL / MnO2 composite microspheres to prepare printing ink, dissolve the PCL / MnO2 composite microspheres in a mixed organic solvent, and stir continuously at a speed of 800-1000 rpm for 1-2.5 h until a uniform, transparent, bubble-free printing ink is obtained;

[0010] S2: adding 26-40 parts of SiN to the printing ink prepared in step S1, stirring evenly to obtain a mixed ink, the stirring speed is 400-700 rpm, the stirring time is 15-30 min, the printing model is pre-designed using Auto CAD software, the mixed ink is extruded, and 3D printing is performed to form a 3D printing model;

[0011] S3: The 3D printed model was immersed in 1 mol / L sodium hydroxide solution, hydrolyzed for 10 min, then washed with deionized water until neutral, vacuum dried for 1-3 h, thoroughly washed with anhydrous ethanol to remove the mixed organic solvent, and vacuum dried for 6-12 h to obtain the 3D printed bone repair material.

[0012] Furthermore, the mixed organic solvent in step S1 is prepared by mixing dichloromethane, 2-butylethanol and dibutyl phthalate in a volume ratio of 5:2:1, and the amount ratio of the PCL / MnO2 composite microspheres to the mixed organic solvent is 1 mg:5 mL.

[0013] Furthermore, the printing speed of the 3D printing in step S2 is 10-30 mm / s, the printing layer thickness is 0.03-0.45 mm, and the needle diameter used for printing is 0.02-0.3 mm.

[0014] Furthermore, the preparation of the PCL / MnO2 composite microspheres comprises the following steps:

[0015] (1) Dissolve PCL and MnO2 in a 2.5 wt% dichloromethane solution (oil phase), place in an ice bath, and use a high-speed homogenizer to perform high-speed shear at 5000-20000 rpm to form a uniform colostrum without stratification (W1 / O);

[0016] (2) slowly and evenly injecting the colostrum obtained in step (1) into a 0.5 wt% polyvinyl alcohol (PVA) solution (external aqueous phase, W2 phase), and evenly dispersing the colostrum at a speed of 5000-20000 rpm using a high-speed homogenizer under ice bath conditions to obtain double emulsions;

[0017] (3) The mixture was stirred at 500 rpm for 4 h using a magnetic stirrer to completely evaporate the dichloromethane. Subsequently, the mixture was centrifuged at 800 rpm for 6 min to obtain a precipitate. The precipitate was washed three times with deionized water and freeze-dried for 48 h to obtain PCL / MnO2 composite microspheres.

[0018] Furthermore, the amount ratio of PCL, MnO2 and dichloromethane solution in step (1) is 3 mg:2 mg:10 mL, and the volume ratio of colostrum and 0.5 wt% polyvinyl alcohol (PVA) solution in step (2) is 1:30.

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

[0020] The 3D printed bone repair material prepared by the present invention has good mechanical properties, biocompatibility, antibacterial properties and biodegradability, promotes cell proliferation, and accelerates bone repair and bone regeneration. PCL / MnO2 composite microspheres are combined with SiN, PCL has good biocompatibility and biodegradability, but the degradation rate is slow, the initial mechanical properties are insufficient, and the products during the degradation process will lead to an acidic environment, which is easy to cause inflammation and bone absorption at the implant site. The introduction of SiN, on the one hand, SiN can be used as a reinforcing phase to improve the mechanical properties of the composite microspheres, meet the mechanical strength requirements of bone implant substitute materials, and solve the problem of insufficient initial mechanical strength of pure PCL materials in the bone repair process; on the other hand, the addition of SiN can alleviate the influence of PCL degradation acid products, improve the biocompatibility of the material, thereby reducing the occurrence of aseptic inflammation and providing a favorable environment for the growth of bone tissue. SiN exhibits enhanced osteogenicity, hardness and antibacterial properties. When it is compounded with PCL, the two are in a dense form. SiN particles are evenly distributed in PCL / MnO2. The SiN particles are nanoscale and show a ꞵ phase of SiN, which can improve fracture toughness and enhance cell antibacterial and osteogenic properties. At the same time, the addition of SiN increases the degradation rate of PCL to a certain extent, so that the mechanical properties of the material are prolonged and protected, which is beneficial to bone repair and healing, and avoids the problem of secondary surgery. SiN can promote the formation of alkaline phosphatase and calcium nodule deposition in adipose stem cells, and can promote the expression of a series of osteogenic proteins, thereby accelerating osteogenesis. Moreover, the compounding of PCL and MnO2 can deliver manganese ions for tissue engineering, and the reaction can release oxygen, enter the tissue and improve the microenvironment of the wound site. Oxygen has the ability to enhance the secretion of osteoblasts into osteogenic genes. In the damaged microenvironment, the increase in dissolved oxygen levels can improve the hypoxia caused by tissue damage. This regulation helps to maintain the oxygen concentration required for normal cell metabolism and accelerate the bone repair process. The manganese ions released by MnO2 and SiN can promote calcium deposition, which is beneficial to promote bone growth and promote bone defect repair and bone regeneration together with SiN. The prepared 3D printed bone repair material promotes the deposition of fibrous tissue, especially collagen fibers, and provides a scaffold attachment effect for inorganic matter at the defect site. Over time, the amount of fibrous tissue generated is also increasing, indicating that the prepared 3D printed bone repair material continuously releases SiN at the defect site, thereby continuously promoting fiber formation, and the prepared 3D printed bone repair material itself is also degrading over time, providing the necessary space for new bone formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The water contact angle diagrams of the materials prepared in Example 2 of the present invention and Comparative Examples 1-3;

[0023] Figure 2 The bone volume fraction diagram of the materials prepared in Example 2 of the present invention and Comparative Examples 1-3;

[0024] Figure 3 The pH value variation diagram of the materials prepared in Example 2 and Comparative Examples 1-3 during the degradation process of the present invention;

[0025] Figure 4 This is a graph of dissolved oxygen concentration of materials prepared in Example 2 of the present invention and Comparative Examples 1-3;

[0026] Figure 5 This is a graph showing the amount of calcium deposition in the materials prepared in Example 2 of the present invention and Comparative Examples 1-3. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0028] Example 1: This example proposes a 3D printed bone repair material, which is prepared from the following raw materials in parts by weight: 60 parts of PCL (polycaprolactone) / MnO2 composite microspheres and 40 parts of SiN.

[0029] This embodiment also provides a method for preparing a 3D printed bone repair material, which specifically includes the following steps:

[0030] S1: Take 60 parts of modified PCL / MnO2 composite microspheres to prepare printing ink, dissolve the PCL / MnO2 composite microspheres in a mixed organic solvent, wherein the mixed organic solvent is a mixture of dichloromethane, 2-butyl ethanol and dibutyl phthalate in a volume ratio of 5:2:1, and the amount ratio of PCL / MnO2 composite microspheres to the mixed organic solvent is 1 mg:5 mL, and stir continuously at a speed of 800 rpm for 1 h until a uniform, transparent, bubble-free printing ink is obtained;

[0031] S2: Take 40 parts of SiN and add it to the printing ink prepared in step S1, stir evenly to obtain a mixed ink, the stirring speed is 400 rpm, the stirring time is 15 min, the printing model is pre-designed using Auto CAD software, the mixed ink is extruded, 3D printing is performed to form a 3D printing model, the printing speed is 5 mm / s, the printing layer thickness is 0.03 mm, and the needle diameter used for printing is 0.02 mm;

[0032] S3: The 3D printed model was immersed in 1 mol / L sodium hydroxide solution, hydrolyzed for 10 min, then washed with deionized water until neutral, vacuum dried for 1 h, thoroughly washed with anhydrous ethanol to remove the mixed organic solvent, and vacuum dried for 6 h to obtain the 3D printed bone repair material.

[0033] The preparation of the PCL / MnO2 composite microspheres comprises the following steps:

[0034] (1) PCL and MnO2 were dissolved in a 2.5 wt% dichloromethane solution (oil phase). The amount ratio of PCL, MnO2 and dichloromethane solution was 3 mg:2 mg:10 mL. In an ice bath, a high-speed homogenizer was used for high-speed shearing at 3000 rpm to form a uniform colostrum without stratification (W1 / O).

[0035] (2) slowly and evenly injecting the colostrum obtained in step (1) into a 0.5 wt% polyvinyl alcohol (PVA) solution (external aqueous phase, W2 phase), wherein the volume ratio of colostrum to 0.5 wt% polyvinyl alcohol (PVA) solution is 1:30, and uniformly dispersing the colostrum at a speed of 4000 rpm using a high-speed homogenizer under ice bath conditions to obtain double emulsions;

[0036] (3) The mixture was stirred at 500 rpm for 2 h using a magnetic stirrer to completely evaporate the dichloromethane. Subsequently, the mixture was centrifuged at 800 rpm for 6 min to obtain a precipitate. The precipitate was washed three times with deionized water and freeze-dried for 48 h to obtain PCL / MnO2 composite microspheres.

[0037] Example 2: This example proposes a 3D printed bone repair material, which is prepared from the following raw materials in parts by weight: 70 parts of PCL (polycaprolactone) / MnO2 composite microspheres and 30 parts of SiN.

[0038] This embodiment also provides a method for preparing a 3D printed bone repair material, which specifically includes the following steps:

[0039] S1: Take 70 parts of PCL / MnO2 composite microspheres to prepare printing ink, dissolve the PCL / MnO2 composite microspheres in a mixed organic solvent, wherein the mixed organic solvent is a mixture of dichloromethane, 2-butyl ethanol and dibutyl phthalate in a volume ratio of 5:2:1, and the amount ratio of PCL / MnO2 composite microspheres to the mixed organic solvent is 1 mg:5 mL, and stir continuously at a speed of 850 rpm for 1.5 h until a uniform, transparent, bubble-free printing ink is obtained;

[0040] S2: 30 parts of SiN are added to the printing ink prepared in step S1, and stirred evenly to obtain a mixed ink. The stirring speed is 500 rpm, and the stirring time is 20 min. The printing model is pre-designed using Auto CAD software, and the mixed ink is extruded and 3D printed to form a 3D printed model. The printing speed is 10 mm / s, the printing layer thickness is 0.2 mm, and the needle diameter used for printing is 0.1 mm;

[0041] S3: The 3D printed model was immersed in 1 mol / L sodium hydroxide solution, hydrolyzed for 10 min, then washed with deionized water until neutral, vacuum dried for 1.5 h, thoroughly washed with anhydrous ethanol to remove the mixed organic solvent, and vacuum dried for 8 h to obtain the 3D printed bone repair material.

[0042] The preparation of the PCL / MnO2 composite microspheres comprises the following steps:

[0043] (1) PCL and MnO2 were dissolved in a 2.5 wt% dichloromethane solution (oil phase), with the amount ratio of PCL, MnO2 and dichloromethane solution being 3 mg:2 mg:10 mL. In an ice bath, a high-speed homogenizer was used for high-speed shearing at 8000 rpm to form a uniform colostrum without stratification (W1 / O).

[0044] (2) slowly and evenly injecting the colostrum obtained in step (1) into a 0.5 wt% polyvinyl alcohol (PVA) solution (external aqueous phase, W2 phase), wherein the volume ratio of colostrum to 0.5 wt% polyvinyl alcohol (PVA) solution is 1:30, and uniformly dispersing the colostrum at a speed of 8000 rpm using a high-speed homogenizer under ice bath conditions to obtain double emulsions;

[0045] (3) The mixture was stirred at 500 rpm for 3 h using a magnetic stirrer to completely evaporate the dichloromethane. Subsequently, the mixture was centrifuged at 800 rpm for 6 min to obtain a precipitate. The precipitate was washed three times with deionized water and freeze-dried for 48 h to obtain PCL / MnO2 composite microspheres.

[0046] Example 3: This example proposes a 3D printed bone repair material, which is prepared from the following raw materials in parts by weight: 80 parts of PCL (polycaprolactone) / MnO2 composite microspheres and 29 parts of SiN.

[0047] This embodiment also provides a method for preparing a 3D printed bone repair material, which specifically includes the following steps:

[0048] S1: Take 80 parts of PCL / MnO2 composite microspheres to prepare printing ink, dissolve the PCL / MnO2 composite microspheres in a mixed organic solvent, wherein the mixed organic solvent is a mixture of dichloromethane, 2-butyl ethanol and dibutyl phthalate in a volume ratio of 5:2:1, and the amount ratio of PCL / MnO2 composite microspheres to the mixed organic solvent is 1 mg:5 mL, and stir continuously at a speed of 900 rpm for 2 h until a uniform, transparent, bubble-free printing ink is obtained;

[0049] S2: Take 29 parts of SiN and add it to the printing ink prepared in step S1, stir evenly to obtain a mixed ink, the stirring speed is 600 rpm, the stirring time is 25 min, the printing model is pre-designed using Auto CAD software, the mixed ink is extruded, 3D printing is performed to form a 3D printing model, the printing speed is 25 mm / s, the printing layer thickness is 0.3 mm, and the needle diameter used for printing is 0.2 mm;

[0050] S3: The 3D printed model was immersed in 1 mol / L sodium hydroxide solution, hydrolyzed for 10 min, then washed with deionized water until neutral, vacuum dried for 1-3 h, thoroughly washed with anhydrous ethanol to remove the mixed organic solvent, and vacuum dried for 10 h to obtain the 3D printed bone repair material.

[0051] The preparation of the PCL / MnO2 composite microspheres comprises the following steps:

[0052] (1) PCL and MnO2 were dissolved in a 2.5 wt% dichloromethane solution (oil phase), with the amount ratio of PCL, MnO2 and dichloromethane solution being 3 mg:2 mg:10 mL. In an ice bath, a high-speed homogenizer was used for high-speed shearing at 12,000 rpm to form a uniform colostrum without stratification (W1 / O).

[0053] (2) slowly and evenly injecting the colostrum obtained in step (1) into a 0.5 wt% polyvinyl alcohol (PVA) solution (external aqueous phase, W2 phase), wherein the volume ratio of colostrum to 0.5 wt% polyvinyl alcohol (PVA) solution is 1:30, and uniformly dispersing the colostrum at a speed of 14,000 rpm using a high-speed homogenizer under ice bath conditions to obtain double emulsions;

[0054] (3) The mixture was stirred at 500 rpm for 4 h using a magnetic stirrer to completely evaporate the dichloromethane. Subsequently, the mixture was centrifuged at 800 rpm for 6 min to obtain a precipitate. The precipitate was washed three times with deionized water and freeze-dried for 48 h to obtain PCL / MnO2 composite microspheres.

[0055] Example 4: This example proposes a 3D printed bone repair material, which is prepared from the following raw materials in parts by weight: 90 parts of PCL (polycaprolactone) / MnO2 composite microspheres and 26 parts of SiN.

[0056] This embodiment also provides a method for preparing a 3D printed bone repair material, which specifically includes the following steps:

[0057] S1: Take 90 parts of PCL / MnO2 composite microspheres to prepare printing ink, dissolve the PCL / MnO2 composite microspheres in a mixed organic solvent, wherein the mixed organic solvent is a mixture of dichloromethane, 2-butyl ethanol and dibutyl phthalate in a volume ratio of 5:2:1, and the amount ratio of PCL / MnO2 composite microspheres to the mixed organic solvent is 1 mg:5 mL, and stir continuously at a speed of 1000 rpm for 2.5 h until a uniform, transparent, bubble-free printing ink is obtained;

[0058] S2: Take 26 parts of SiN and add it to the printing ink prepared in step S1, stir evenly to obtain a mixed ink, the stirring speed is 400-500 rpm, the stirring time is 15-30 min, the printing model is pre-designed using Auto CAD software, the mixed ink is extruded, 3D printing is performed to form a 3D printing model, the printing speed is 30 mm / s, the printing layer thickness is 0.45 mm, and the needle diameter used for printing is 0.3 mm;

[0059] S3: The 3D printed model was immersed in 1 mol / L sodium hydroxide solution, hydrolyzed for 10 min, then washed with deionized water until neutral, vacuum dried for 3 h, thoroughly washed with anhydrous ethanol to remove the mixed organic solvent, and vacuum dried for 12 h to obtain the 3D printed bone repair material.

[0060] The preparation of the PCL / MnO2 composite microspheres comprises the following steps:

[0061] (1) PCL and MnO2 were dissolved in a 2.5 wt% dichloromethane solution (oil phase). The amount ratio of PCL, MnO2 and dichloromethane solution was 3 mg:2 mg:10 mL. In an ice bath, a high-speed homogenizer was used for high-speed shearing at 20,000 rpm to form a uniform colostrum without stratification (W1 / O).

[0062] (2) slowly and evenly injecting the colostrum obtained in step (1) into a 0.5 wt% polyvinyl alcohol (PVA) solution (external aqueous phase, W2 phase), wherein the volume ratio of colostrum to 0.5 wt% polyvinyl alcohol (PVA) solution is 1:30, and uniformly dispersing the colostrum at a speed of 20,000 rpm using a high-speed homogenizer under ice bath conditions to obtain double emulsions;

[0063] (3) The mixture was stirred at 500 rpm for 6 h using a magnetic stirrer to completely evaporate the dichloromethane. Subsequently, the mixture was centrifuged at 800 rpm for 6 min to obtain a precipitate. The precipitate was washed three times with deionized water and freeze-dried for 48 h to obtain PCL / MnO2 composite microspheres.

[0064] The difference between Comparative Example 1 and Example 2 is that the incorporation of PCL is eliminated, and the rest is the same as Example 2.

[0065] The difference between Comparative Example 2 and Example 2 is that the addition of MnO2 is eliminated, and the rest is the same as Example 2.

[0066] Compared with Example 2, Comparative Example 3 eliminates the doping of SiN, and the rest is the same as Example 2.

[0067] Experimental Example 1: Mechanical Properties

[0068] Bending performance test: The bending performance of the composite material was experimentally determined according to GB / T1449. According to the method in 3.3.2, the 3D printed bone repair materials prepared by Examples 1-4 and Comparative Examples 1-3 were 3D printed respectively. Standard bending parts of 80 mm×10 mm×4 mm were 3D printed for three-point bending test. The test speed was 2 mm / min. Three parallel samples were set for each group in the experiment. The test data records are shown in Table 1.

[0069] Compressive performance test: The compressive performance of the composite material was experimentally determined according to GB / T1448. According to the method in 3.3.2, the 3D printed bone repair materials prepared by Examples 1-4 and Comparative Examples 1-3 were 3D printed respectively, and 10 mm×10 mm×5 mm porous scaffolds were 3D printed for compressive performance test. The test speed was 2 mm / min. Three parallel samples were set for each group in the experiment. The test data are recorded in Table 1.

[0070] Experimental Example 2: Antibacterial Properties

[0071] The antibacterial method was used to determine the antibacterial property of the material. Staphylococcus aureus was used as the strain, and the 3D printed bone repair materials of Examples 1-4 and Comparative Examples 1-3 were used to 3D print scaffolds. The liquid culture medium was configured as follows: 10 g of peptone, 5 g of sodium chloride and 4 g of beef extract were dissolved in 1000 mL of deionized water, and sterilized at high temperature and high pressure. The Staphylococcus aureus solution stored in a refrigerator at 4 °C was taken out and revived in a 37 °C warm water bath for standby use. The above-mentioned standby materials were moved to an ultra-clean workbench, and 40 mL of liquid culture medium was taken out and added to a conical flask using a pipette, and 100 μL of the bacterial solution was mixed with the liquid culture medium, and the mixed bacterial solution was cultured at 37 °C and 140 r / min for 18 hours. At the same time, a solid culture medium was prepared by selecting 7 g agar, 10 g peptone, 5 g sodium chloride and 4 g beef extract and completely dissolving them in 1000 mL of deionized water. After high temperature and high pressure sterilization, the mixture was poured into a sterile culture dish and stored for later use.

[0072] Before the antibacterial zone experiment, the prepared scaffold was first placed in a 24-well plate and irradiated under ultraviolet light for 12 hours for sterilization pretreatment. 100 μL of activated bacterial solution was transferred to the solid culture medium by a pipette, and the bacterial solution was evenly spread on the surface of the solid culture medium using a spreader. The experimental materials were soaked in water for 1 second and then placed in the solid culture medium coated with bacterial solution. One drop of PBS buffer was added for drug release. After the above operations were completed, the solid culture medium carrying the bacterial solution and experimental materials was placed in a 37 ℃ constant temperature biological incubator, and sterilized water was poured in. After 24 hours of incubation, observation was made. The antibacterial rate results are recorded in Table 1.

[0073] Table 1

[0074]

[0075] Experimental Example 3: Cell Viability and Proliferation

[0076] By replicating the rat skull defect model, the bone repair effect of the membrane material was evaluated using the defect model. 36 SPF-grade male SD rats were used as experimental animals, weighing about 200g. The animal quality license number was SCXK (Shanghai) 2018-0006. The experimental process followed the requirements of animal ethics. The 3D printed bone repair material prepared in Example 2 and Comparative Examples 1-3 was tested, and a control group was set up. The control group did not add any bone repair material, and the rats were grouped. After the rats were anesthetized by intraperitoneal anesthesia, a 2 cm linear incision was made in the center of the rat skull, and a diameter osteotomy drill was used to drill a hole with a diameter of 8 mm at the bone defect above the lambdoid suture. The material was implanted into the skull defect of each group of rats, and the periosteum, subcutaneous tissue and skin were sutured layer by layer. The incision was disinfected, 1 ml of normal saline was injected intraperitoneally for fluid replacement, and antibiotics were injected intramuscularly after surgery to prevent infection. The defect was observed at the 4th and 12th weeks, respectively.

[0077] At 4 and 12 weeks after surgery, the rats were killed by cervical dislocation after intraperitoneal anesthesia, and skull specimens were collected. Excess muscle tissue was trimmed to fully expose bone tissue. After fixation with 4% paraformaldehyde for 72 hours, the skull specimens were scanned at 80 kV using a Micro-CT scanner with an 18-μm pixel size (MCT-Sharp, ZKKS) to reconstruct three-dimensional skull images. The scanning parameters were 70 kV and 100 μA. The images of the defect were reconstructed three-dimensionally and quantitatively analyzed, and the bone volume fraction (BV / TV, %) was used to analyze the new bone formation, such as Figure 2 As shown, an increase in bone volume fraction indicates increased new bone formation.

[0078] Figure 1 The water contact angle diagram of the materials prepared in Example 2 of the present invention and Comparative Examples 1-3 shows that the hydrophobicity is higher without adding SiN, and the hydrophilicity is significantly enhanced after adding SiN. The introduction of SiN significantly improves the hydrophilicity of the material and enhances the biocompatibility. Figure 2 is a graph of bone volume fractions of Example 2 of the present invention, Comparative Examples 1-3 and a control group, showing that the introduced MnO2 and SiN promote bone regeneration; Figure 3 This is a graph showing the pH value changes of the prepared 3D printed bone repair material during the degradation process. Figure 3 It can be concluded that the addition of SiN significantly improved the acidic environment of the degradation products and avoided inflammation caused by the acidic environment. Figure 4 It can be seen that the composite material PCL / MnO2 can continuously release oxygen, thereby promoting bone growth; Figure 5 It can be seen that the calcium accumulation of the 3D bone repair material introduced with MnO2 and SiN reached 12.6 mg, which significantly increased the concentration of calcium ions and promoted bone synthesis.

[0079] In summary, by introducing SiN into the composite material, the hydrophilicity of the material is significantly improved, which is conducive to the normal progress of bone transplantation, and the acidic environment of the material during the degradation process is improved, inflammation and bone resorption are avoided, SiN can promote the expression of bone protein, which is conducive to the deposition of calcium ions, thereby accelerating the proliferation of bone precursor cells and improving the repair speed of bone defects, MnO2 can release oxygen and manganese ions, and manganese ions are conducive to calcium deposition. The presence of oxygen avoids inflammation caused by local hypoxia, and PCL is combined with SiN to improve the degradation rate, so that the regeneration of bone is not affected too slowly or too quickly, and sufficient space is provided for new bone. Due to the good antibacterial property of SiN, bacterial infection is avoided in the bone transplantation process. The 3D printed bone repair material prepared by the present invention has good mechanical properties, biocompatibility, antibacterial property and biodegradability, promotes cell proliferation, and accelerates bone repair and bone regeneration.

[0080] 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 3D printed bone repair material, characterized in that: Prepared from the following raw materials in parts by weight: 60-90 parts of PCL / MnO2 composite microspheres, 26-40 parts of SiN; The preparation method of the 3D printed bone repair material specifically comprises the following steps: S1: Take 60-90 parts of PCL / MnO2 composite microspheres to prepare printing ink, dissolve the PCL / MnO2 composite microspheres in a mixed organic solvent, and stir continuously until a uniform, transparent, bubble-free printing ink is obtained; S2: adding 26-40 parts of SiN to the printing ink prepared in step S1, stirring evenly to obtain a mixed ink, extruding the mixed ink, and performing 3D printing to form a 3D printed model; S3: soaking the 3D printed model in a sodium hydroxide solution, hydrolyzing it, washing it with deionized water until it is neutral, vacuum drying it, and thoroughly washing it with anhydrous ethanol to remove the organic solvent, and then vacuum drying it for the second time to obtain the 3D printed bone repair material; The PCL / MnO2 composite microspheres are prepared from the following raw materials: PCL and MnO2; The preparation method of the PCL / MnO2 composite microspheres specifically comprises the following steps: (1) Dissolve PCL and MnO2 in a 2.5 wt% dichloromethane solution, place in an ice bath, and use a high-speed homogenizer to perform high-speed shearing at 5000-20000 rpm to form a uniform colostrum without stratification; (2) slowly and evenly injecting the colostrum obtained in step (1) into a 0.5 wt% polyvinyl alcohol solution, and evenly dispersing the colostrum at a speed of 5000-20000 rpm using a high-speed homogenizer under ice bath conditions to obtain double emulsions; (3) The double emulsion obtained in step (2) is subjected to magnetic stirring to completely evaporate the dichloromethane, and then stirred and centrifuged to obtain a precipitate, which is washed and freeze-dried to obtain PCL / MnO2 composite microspheres.

2. A 3D printed bone repair material according to claim 1, characterized in that: The mixed organic solvent in step S1 is prepared by mixing dichloromethane, 2-butylethanol and dibutyl phthalate in a volume ratio of 5:2:1, the amount ratio of PCL / MnO2 composite microspheres to the mixed organic solvent is 1 mg:5 mL, the stirring speed is 1000 rpm, and the time is 2.5 h.

3. A 3D printed bone repair material according to claim 1, characterized in that: In step S2, the stirring speed is 400-700 rpm, the stirring time is 15-30 min, the 3D printing speed is 10-30 mm / s, the printing layer thickness is 0.03-0.45 mm, and the inner diameter of the needle used for printing is 0.02-0.3 mm.

4. A 3D printed bone repair material according to claim 1, characterized in that: The vacuum drying time in step S3 is 1-3 h, and the second vacuum drying time is 6-12 h.

5. A 3D printed bone repair material according to claim 1, characterized in that: The amount ratio of PCL, MnO2 and dichloromethane solution in step (1) is 3 mg:2 mg:10 mL, and the volume ratio of colostrum to 0.5 wt% polyvinyl alcohol solution in step (2) is 1:

30.

6. A 3D printed bone repair material according to claim 1, characterized in that: The magnetic stirring in step (3) is performed using a magnetic stirrer, with a stirring speed of 500 rpm and a stirring time of 4 h. The stirring is centrifuged, with a stirring speed of 800 rpm and a centrifugal time of 6 min.

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