An artificial bone repair body based on 3D printing and its preparation method

Abstract

The present invention discloses an artificial bone repair body based on 3D printing and a preparation method thereof. The preparation method comprises the following steps: (1) uniformly mixing polycaprolactone and a porous tricalcium phosphate powder material; (2) making the uniformly mixed material into a solid printing raw material; (3) melting and printing the solid printing raw material through a 3D printer according to a preset model to obtain the artificial bone repair body; wherein, the porous tricalcium phosphate powder material is formed by drying a precipitate after a salt solution mixture reacts, and the salt solution comprises a calcium salt and a phosphate solution. The artificial bone repair body of the present invention has excellent degradation performance, mechanical strength and biological activity, and avoids the problem of cytotoxicity caused by residual organic solvents.

Description

Technical Field

[0001] The present invention relates to an artificial bone repair body based on 3D printing and a preparation method thereof, in particular to a preparation method of a polycaprolactone / porous tricalcium phosphate composite artificial bone repair body. Background Art

[0002] A series of etiologies such as tumors, traumas, necrosis, and congenital malformations often lead to large-volume bone structure destruction and bone defects, and there is an urgent need to develop new artificial bone materials for bone defect repair. The pore structure of artificial bone materials has a crucial impact on their mechanical properties and biological functions. Generally, too high a porosity results in low mechanical strength, while too low a porosity will prevent the ingrowth of new bone tissue. To ensure the ingrowth of bone tissue, the pore diameter is generally greater than 100 microns, and the pores should be interconnected. The traditional manufacturing process of artificial bone materials has low precision, and special pore structures cannot be obtained using traditional pore-forming agents, which is not conducive to new bone ingrowth and angiogenesis. 3D printing technology constructs objects by layer-by-layer printing, with high product precision, high material utilization rate, and the ability to construct complex pore structures, showing significant advantages in the field of orthopedics.

[0003] At present, the 3D printing materials for biomedical applications mainly include polyetheretherketone and polylactic acid materials. The polyetheretherketone material is processed by laser melting and has the characteristics of high mechanical strength and good chemical inertness, and is widely used in the field of skull printing. However, polyetheretherketone is difficult to degrade in the body and has poor biological activity. See Reference 1: Singh S., Prakash C. and et al. Plasma treatment of polyether-ether-ketone: A means of obtaining desirable biomedical characteristics. Eur. Polym. J. 2019, 118: 561-577. The polylactic acid material is formed by stacking filamentous materials layer by layer through the fused deposition modeling method. This modeling method has high precision, low cost and strong repeatability during the printing process, and the obtained polylactic acid scaffold has relatively high mechanical strength. However, the degradation products of polylactic acid are acidic, which is not conducive to new bone growth, and the toughness is poor. See Reference 2: Lipsa R., Tudorachi N. and et al. Biodegradation of poly(lactic acid) and some of its based systems with Trichoderma viride. Int. J. Biol. Macromol. 2016, 88: 515-526. Researchers have added calcium phosphate materials such as hydroxyapatite to the printing materials to improve the biocompatibility of artificial bone scaffolds, but there are still problems such as non-degradability in the body or mismatch between the degradation rate and the osteogenic cycle, and low biological activity, which are difficult to meet the growing market demand. See Reference 3: Pan Y., Chen Y. and et al. Effect of notch sensitivity on the mechanical properties of HA / PEEK functional gradient biocomposites. J. Polym. Eng. 2016, 36: 933-941. Research shows that the degradation period of hydroxyapatite can reach more than ten years. After the dense hydroxyapatite material is implanted, only new bone tissue is formed on the surface, lacking the ability to induce bone formation.

[0004] Therefore, there is an urgent need to develop 3D printing composite artificial bone materials with higher biological activity and complete degradation in the body. Summary of the Invention

[0005] The object of the present invention is to provide an artificial bone repair body based on 3D printing and a preparation method thereof. The artificial bone repair body has excellent degradation performance, mechanical strength and biological activity, and avoids the cytotoxicity problem caused by residual organic solvents.

[0006] One aspect of the present invention provides a preparation method of an artificial bone repair body based on 3D printing, including the following steps:

[0007] (1) Mix polycaprolactone and porous tricalcium phosphate powder materials evenly;

[0008] (2) Make the mixed material into a solid printing raw material;

[0009] (3) According to a preset model, melt-print the artificial bone repair body from the solid printing raw material through a 3D printer;

[0010] Among them, the porous tricalcium phosphate powder material is formed by drying the precipitate after the reaction of the salt solution mixture, and the salt solution includes a calcium salt and a phosphate solution.

[0011] In a preferred embodiment, in step (1), the polycaprolactone and the porous tricalcium phosphate powder material are mixed evenly by a mechanical method or a solvent dissolution method.

[0012] In a more preferred embodiment, the polycaprolactone and the porous tricalcium phosphate powder material are added to a mixer and heated and mixed. The obtained mixed material is put into a granulator and crushed, and then added to the mixer and mixed evenly again.

[0013] Further, step (1) is specifically implemented as follows: The polycaprolactone and the porous tricalcium phosphate powder material are added to a mixer and heated and mixed. The heating temperature is 30-200 °C, and the mixing time is 0.5-12 hours; the obtained mixed material is put into a granulator and crushed to form particulate materials with a diameter of 0.1-10 mm; then added to the mixer and mixed evenly again. The heating temperature is 50-150 °C, and the mixing time is 0.5-12 hours to obtain a uniformly mixed polycaprolactone / porous tricalcium phosphate powder material composite.

[0014] In a more preferred embodiment, step (1) is specifically implemented as follows: The polycaprolactone and the porous tricalcium phosphate powder material are respectively dissolved in a solvent, stirred evenly and then mixed, and then injected into pure water; the precipitated matter is collected by suction filtration and dried for 6-24 hours to obtain a uniformly mixed polycaprolactone / porous tricalcium phosphate powder material composite fiber.

[0015] Further, the solvent includes one or a combination of more of N,N-dimethylformamide (DMF), chloroform, acetone, toluene, and carbon tetrachloride. The mass ratio of the solid material to the solvent is 0.01 to 0.2, the volume ratio of the mixed solvent to pure water is 0.05 to 0.2, and the drying temperature is 30 to 100 °C.

[0016] In a preferred embodiment, the molecular weight of polycaprolactone is 50,000 to 200,000 Da.

[0017] In a preferred embodiment, in the material after mixing in step (1), the mass content of the porous tricalcium phosphate powder material is less than 50%; more preferably 10 to 50%; further 10 to 40; still further 25 to 40%. Optionally, the mass content of the porous tricalcium phosphate powder material in the mixed material is 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%.

[0018] In a preferred embodiment, in step (2), the solid printing material is a wire, the wire is made by a screw wire extruder, the temperature of the screw wire extruder is set to 60 to 130 °C, and the wire making speed is 0.1 to 5 m / min.

[0019] In a preferred embodiment, in step (3), the parameters of the 3D printer are set as follows: the printing temperature is 120 to 250 °C, the printing speed is 5 to 70 mm / s, the filling rate is 20 to 100%, and the wire diameter width is 0.1 to 0.8 mm.

[0020] In a preferred embodiment, the salt solution further includes a magnesium salt, and the porous tricalcium phosphate powder material contains 1 to 3% by mass of magnesium element. More preferably, the mass percentage of magnesium element is 1.3 to 2%. Optionally, the mass percentage of magnesium element is 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.7%, 1.9%, 2%, 2.2%, 2.5%, 2.8% or 3%.

[0021] In a preferred embodiment, the porous tricalcium phosphate powder material is prepared by the following steps:

[0022] Prepare a first solution containing calcium ions; prepare a phosphate solution and adjust the pH to 9.5 to 10.5 with an alkali solution as the second solution;

[0023] Heat and mix the first solution and the second solution, and react under stirring conditions at 60 to 95 °C;

[0024] Centrifuge the suspension obtained after the reaction to take the precipitate, wash it, and spray-dry the washed precipitate to obtain the porous tricalcium phosphate powder material.

[0025] In a more preferred embodiment, the first solution further contains magnesium ions, and the molar ratio of calcium ions to magnesium ions in the first solution is 6-10; after the first solution and the second solution are mixed, the molar ratio of calcium ions to phosphate ions is 1.1-1.5; the calcium salt is selected from one or a combination of more than one of anhydrous calcium chloride, calcium chloride dihydrate, and calcium nitrate tetrahydrate, the magnesium salt is selected from magnesium chloride hexahydrate and / or magnesium nitrate hexahydrate, the phosphate is selected from one or a combination of more than one of disodium hydrogen phosphate, diammonium hydrogen phosphate, and sodium hydrogen phosphate, and the alkaline solution is ammonia water or sodium hydroxide.

[0026] In a more preferred embodiment, a spray dryer is used to spray-dry the washed precipitate. The inlet air temperature of the spray dryer is 240-300 °C, the outlet air temperature is 120-150 °C, and the feeding rate is 30-200 mL / min.

[0027] According to the second aspect of the present invention, there is provided an artificial bone repair body based on 3D printing, which is prepared by the preparation method described above.

[0028] In a preferred embodiment, the porosity of the artificial bone repair body is 30-70%, the maximum pore diameter is greater than 300 μm, and the mechanical strength is 2-20 MPa.

[0029] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0030] In the artificial bone repair body based on 3D printing and its preparation method of the present invention, a special porous tricalcium phosphate powder material is compounded into a biodegradable polycaprolactone material to obtain a solid printing raw material, and then an artificial bone repair body is melt-printed by a 3D printer. It has better degradation performance, mechanical properties and biological activity. In particular, it can avoid the cytotoxicity problem caused by organic solvents. The internal pores formed are interconnected, which is conducive to the growth of new bone, material transport and vascularization. Description of the Drawings

[0031] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 XRD results of the porous tricalcium phosphate powder material prepared in Example 1.

[0033] Figure 2 SEM micrograph of the porous tricalcium phosphate powder material prepared in Example 1.

[0034] Figure 3 EDS energy spectrum diagram of the porous tricalcium phosphate powder material prepared in Example 1.

[0035] Figure 4 Photo of the artificial bone repair body prepared in Example 1 of the present invention.

[0036] Figure 5 SEM micrograph of the artificial bone repair body prepared in Example 1 of the present invention.

[0037] Figures 6(a) and 6(c) are respectively the microscopic observation results of culturing MC3T3-E1 bone precursor cells in the leaching solution of the artificial bone repair body prepared in Example 1 after 1 day and 3 days; Figures 6(b) and 6(d) are respectively the microscopic observation results of culturing MC3T3-E1 bone precursor cells in the blank control group after 1 day and 3 days. Detailed implementation manners

[0038] The following elaborates on the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] For the 3D printing products of polycaprolactone and tricalcium phosphate, if the tricalcium phosphate raw material obtained by conventional calcination and grinding is used, that is: prepared by calcination at 1200 degrees, and then ground and sieved to obtain a micron-sized hard tricalcium phosphate material. This micron-sized hard tricalcium phosphate material has poor mixing performance in polycaprolactone, so only a low-concentration solution of polycaprolactone and tricalcium phosphate organic solvent can be obtained by the solvent method to get a uniform composite material. However, the solvent method has the problem of solvent residue toxicity, which limits its actual clinical application. Composite hydroxyapatite in 3D printing products, its chemical composition is the same as the inorganic component in human bones, which has a promoting effect on the adhesion and proliferation of osteoblasts, and also shows good biocompatibility after being implanted into the body. However, its degradation in the body is slow. Research shows that the degradation period of hydroxyapatite can reach more than ten years. After the dense hydroxyapatite material is implanted, only new bone tissue is formed on the surface, lacking the ability to induce bone formation.

[0040] Based on this, the inventor uses the low-temperature wet chemical precipitation method to obtain a low-density porous tricalcium phosphate material, and the doped active magnesium element is beneficial to osteogenesis. It can be mixed with polycaprolactone by the solvent method or a uniform composite material can be prepared by the internal mixer mechanical mixing method to solve the following problems:

[0041] (1) Problem of poor degradation performance

[0042] The common materials for 3D printed artificial bone repair bodies are mainly polyetheretherketone and polylactic acid. Among them, polyetheretherketone does not degrade in the body and has poor binding to bone tissue. The degradation products of polylactic acid are acidic and prone to cause inflammatory reactions. In this application, a fully degradable artificial bone repair body product is prepared by compounding polycaprolactone and tricalcium phosphate (preferably containing magnesium element), and the degradation products are neutral, which is beneficial to the formation of new bone.

[0043] (2) Problem of residual organic solvents

[0044] If polycaprolactone is dissolved in an organic solvent and mixed with tricalcium phosphate powder. Although the good fluidity of the solution helps the materials to be mixed more evenly, the solvent cannot be completely removed in subsequent processes such as drying or suction filtration, resulting in greater cytotoxicity. The raw materials of this application can be completed by a kneading mechanical mixing method to avoid solvent residues.

[0045] (3) Problem of insufficient mechanical strength and bioactivity

[0046] Polycaprolactone is dissolved in an organic solvent and mixed with tricalcium phosphate powder. After freeze-drying the solvent components after 3D printing, the mechanical strength of the scaffold material is only 1-2 MPa, which is not conducive to application in bone tissue. In this application, by using a magnesium-containing tricalcium phosphate material, the mixing performance is improved, so that the mixing process can be completed by a kneading mechanical mixing method, significantly improving the mechanical strength and bioactivity of the material.

[0047] The inventors propose a 3D printed magnesium-containing tricalcium phosphate polycaprolactone artificial bone repair body and its preparation method, which specifically include the following steps:

[0048] (1) Weigh the polycaprolactone and tricalcium phosphate powder materials and mix the two materials evenly.

[0049] (2) The mixed materials are made into filaments through a screw extruder to form filaments.

[0050] (3) After importing the digital model and setting the parameters, use a hot melt extrusion type 3D printer to prepare a tricalcium phosphate / polycaprolactone artificial bone repair body.

[0051] In step (1), the molecular weight of the polycaprolactone material used is 50,000-200,000 Da; the tricalcium phosphate powder material used is prepared by a low-temperature wet chemical method, and the particle size is 1-20 μm; the content of the tricalcium phosphate material in the polycaprolactone / tricalcium phosphate composite material is 0-50 wt.%. Further, the tricalcium phosphate powder material contains magnesium, and the magnesium content is 1-3 wt.%, preferably 1.3-2 wt.%. The content of the tricalcium phosphate material in the polycaprolactone / tricalcium phosphate composite material is preferably 10-50 wt.%.

[0052] In step (1), the two materials can be uniformly mixed by mechanical mixing method. The specific process of mixing the two materials by mechanical mixing method is as follows: Add polycaprolactone and magnesium-containing tricalcium phosphate powder materials into a mixer and heat and mix them. The heating temperature is 30-200 °C, and the mixing time is 0.5-12 hours. The obtained mixed material is put into a granulator for crushing to form granular materials with a diameter of 0.1-10 mm. Then add them into the mixer again for uniform mixing. The heating temperature is 50-150 °C, and the mixing time is 0.5-12 hours to obtain a uniformly mixed polycaprolactone / magnesium-containing tricalcium phosphate composite material.

[0053] In step (1), the two materials can also be uniformly mixed by solvent dissolution method. The specific process of mixing the two materials by solvent dissolution method is as follows: Dissolve and stir polycaprolactone and magnesium-containing tricalcium phosphate materials with solvents respectively. After stirring evenly, mix the two materials and then inject them into pure water. The precipitated sediment is collected by suction filtration and dried for 6-24 hours to obtain a uniformly mixed polycaprolactone / magnesium-containing tricalcium phosphate composite fiber. Among them, the solvents used include but are not limited to N,N-dimethylformamide (DMF), chloroform, acetone, toluene, carbon tetrachloride, etc. The mass ratio of the solid material to the solvent is 0.01-0.2, and the volume ratio of the solvent to water after mixing is 0.05-0.2. The solvent dissolution and stirring time is 10-60 minutes, and the drying temperature is 30-100 °C.

[0054] In step (2), the temperature of the screw extruder used is set at 60-130 °C, and the wire-making speed is 0.1-5 m / min. The content of magnesium-containing tricalcium phosphate in the obtained magnesium-containing tricalcium phosphate polycaprolactone composite wire is 10-50 wt.%.

[0055] In step (3), the parameters of the 3D printer are set as follows: the printing temperature is 120-250 °C, the printing speed is 5-70 mm / s, the filling rate is 20-100%, and the wire diameter width is 0.1-0.8 mm.

[0056] The porosity of the prepared 3D-printed polycaprolactone / magnesium-containing tricalcium phosphate artificial bone repair body is 30-70%, the maximum pore diameter is greater than 300 μm, and the mechanical strength is 2-20 MPa.

[0057] Among them, the above-mentioned magnesium-containing tricalcium phosphate powder material is prepared by the following steps:

[0058] (1) Dissolve calcium salt and magnesium salt in water to obtain a first solution, wherein the concentration of the calcium salt is 1-100 g / L and the concentration of the magnesium salt is 0.4-40 g / L. Further, the molar ratio of calcium ions to magnesium ions is 6-10; the concentration of the calcium salt is more preferably 30-100 g / L, further 50-100 g / L, still further 60-90 g / L, especially 80-90 g / L; for example, 80 g / L, 82 g / L, 84 g / L, 86 g / L, 88 g / L or 90 g / L. Optionally, the concentration of the magnesium salt is more preferably 0.4-30 g / L, further 5-30 g / L, still further 15-30 g / L, especially 20-30 g / L; for example, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 27 g / L or 29 g / L.

[0059] (2) Dissolve phosphate in water and adjust the pH to 9.5-10.5, further 9.8-10.0, using an alkali solution (preferably ammonia water or sodium hydroxide) to obtain a second solution, wherein the concentration of the phosphate is 1-100 g / L. The concentration of the phosphate in the second solution is more preferably 30-100 g / L, further 50-90 g / L, still further 70-90 g / L, especially 80-90 g / L; for example, 81 g / L, 83 g / L, 84 g / L, 85 g / L, 87 g / L or 88 g / L. More preferably, adjust it to 9.8-10.2 using ammonia water. The inventors have found through research that this pH value has an important influence on the preparation of porous magnesium-containing tricalcium phosphate powder. According to the X-ray diffraction results, too high or too low pH value will generate more impurity phases, resulting in more calcium hydrogen phosphate impurity phases or hydroxyapatite in the prepared porous magnesium-containing tricalcium phosphate powder.

[0060] (3) Heat equal volumes of the first solution and the second solution to 60-95 °C and then mix them. Carry out a wet chemical reaction at normal pressure under the conditions of a temperature of 60-95 °C and stirring, wherein the stirring rate is 100-500 rpm, and the molar ratio of calcium ions to phosphate ions is 1.1-1.5.

[0061] (4) Centrifuge the suspension after the wet chemical reaction to obtain a precipitate, wash it 4-8 times by centrifugation with water, add the washed precipitate to 5-20 times the mass of water, stir evenly to form a slurry, and use a spray dryer to process the slurry into porous tricalcium phosphate powder, wherein the inlet air temperature of the spray dryer is 240-300 °C, the outlet air temperature is 120-150 °C, and the feeding rate is 30-200 mL / min.

[0062] The calcium salt is selected from one or a combination of more than one of anhydrous calcium chloride, calcium chloride dihydrate, and calcium nitrate tetrahydrate. The magnesium salt is selected from magnesium chloride hexahydrate and / or magnesium nitrate hexahydrate. The phosphate is selected from one or a combination of more than one of disodium hydrogen phosphate, diammonium hydrogen phosphate, and sodium hydrogen phosphate.

[0063] The micropores of the porous tricalcium phosphate powder exhibit a porous structure. A specific content of magnesium element therein shows excellent bioactivity, effectively promoting new bone formation. Compared with hydroxyapatite, the porous tricalcium phosphate powder material has better degradation performance, thus having significant advantages in the application of bone repair materials. Tricalcium phosphate materials usually need to be prepared by high-temperature calcination above 1000 °C or solid-phase reaction, which consumes a large amount of energy and the product particles are in the micron level, with large density and irregular surfaces. Currently, although some manufacturers can stably produce tricalcium phosphate powder raw materials, most of them calcine the raw materials through the solid-phase reaction method and crush the powder through mechanical grinding. The cost is relatively high, the crystal grains are large after sintering, and the shape is an irregular geometric shape, with poor fluidity during the preparation of liquid-phase composite materials. The tricalcium phosphate powder of this application is prepared based on wet chemical reaction. It directly undergoes wet chemical reaction at 60 - 95 °C under normal pressure to generate a magnesium-containing tricalcium phosphate suspension, and through a special forming method of spray drying, a low-density porous magnesium-containing tricalcium phosphate powder is obtained.

[0064] Example 1: Preparation of porous tricalcium phosphate powder material

[0065] Weighing and dissolving: Weigh 900 g of anhydrous calcium chloride and 270 g of magnesium chloride hexahydrate, and dissolve them in 10 L of water to obtain Solution A; weigh 830 g of diammonium hydrogen phosphate, dissolve it in 10 L of water, and adjust the pH value of the solution to 10.0 using ammonia water to obtain Solution B.

[0066] Heating and mixing: Heat both Solution A and Solution B to 70 °C and mix them, and continuously stir at a speed of 100 rpm to form a suspension.

[0067] Wet chemical reaction: Heat and stir the obtained suspension at 70 °C and 100 rpm for 12 hours.

[0068] Centrifugal cleaning: Centrifuge the suspension after the wet chemical reaction at 2000 rpm for 3 minutes to obtain a precipitate, and add water for centrifugal cleaning 5 times.

[0069] Spray drying: Add the cleaned precipitate to 10 L of water, stir well to form a slurry. Set the inlet air temperature of the spray dryer to 250 °C and the outlet air temperature to 120 °C, and spray-dry the slurry at a rate of 50 mL / min to obtain a low-density porous tricalcium phosphate powder.

[0070] Test: The XRD results, SEM micrographs, and EDS spectra of the prepared porous tricalcium phosphate powder are as follows in sequence Figures 1 to 3 , where the magnesium content is 1.9%, and the particle size is distributed in the range of ~5 - 20 μm.

[0071] Example 2: Preparation of artificial bone repair body

[0072] Weighing and mixing: Weigh 180 g of polycaprolactone and 120 g of the porous tricalcium phosphate powder material prepared in Example 1, add them to a mixer, heat at 100 °C for 1 hour. The obtained mixed material is put into a granulator for crushing to form particle materials with a diameter less than 5 mm. Then add them to the mixer again and mix evenly, heat at 100 °C for 1 hour to obtain a uniformly mixed magnesium-containing tricalcium phosphate / polycaprolactone composite material.

[0073] Filament making: Use a screw extruder, set the feeding temperature at 90 °C, and control the process temperature at 100 °C. Add the uniformly mixed magnesium-containing tricalcium phosphate / polycaprolactone composite material to a twin-screw extruder, set the extruded wire diameter at 2.85 mm, and the filament-making speed at 1 m / min to obtain a wire material for 3D printing, where the content of magnesium-containing tricalcium phosphate is 40 wt%.

[0074] 3D printing: Import the digital model, set the printing temperature at 180 °C, the printing speed at 5 mm / s, the filling rate at 80%, and the wire diameter width at 0.4 mm to prepare a 3D-printed polycaprolactone / tricalcium phosphate artificial bone repair body, as shown in Figure 4 shown.

[0075] Detection: The micrograph of the 3D-printed polycaprolactone / tricalcium phosphate artificial bone repair body is as shown in Figure 5 . Figures 6(a) and 6(c) respectively show the microscopic observation results of culturing MC3T3-E1 bone precursor cells for 1 day and 3 days with the leaching solution of this 3D-printed polycaprolactone / tricalcium phosphate artificial bone repair body; Figures 6(b) and 6(d) respectively show the microscopic observation results of culturing MC3T3-E1 bone precursor cells for 1 day and 3 days with the blank control group, where dmem medium is used as the cell culture medium in both groups of leaching experiments. The cell experiment with the leaching solution shows that the cell growth state is good, the obtained artificial bone repair body has no cytotoxicity, and has good biocompatibility.

[0076] Example 3: Preparation of artificial bone repair body

[0077] Weighing and mixing: Weigh 240 g of polycaprolactone and 60 g of magnesium-containing tricalcium phosphate prepared in Example 1 and add them to a mixer. Heat at 100 °C for 1 hour. The obtained mixed material is put into a granulator for crushing to form particulate materials with a diameter less than 5 mm. Then add it to the mixer again and mix evenly. Heat at 80 °C for 1 hour to obtain a uniformly mixed magnesium-containing tricalcium phosphate / polycaprolactone composite material.

[0078] Filament making: Use a screw extruder with the feeding temperature set at 80 °C and the process temperature controlled at 90 °C. Add the uniformly mixed magnesium-containing tricalcium phosphate / polycaprolactone composite material to a twin-screw extruder, set the extruded filament diameter to 1.75 mm, and the filament-making speed to 1 m / min to obtain a filament for 3D printing, in which the content of magnesium-containing tricalcium phosphate is 20 wt%.

[0079] 3D printing: Import a digital model, set the printing temperature at 130 °C, the printing speed at 20 mm / s, the filling rate at 30%, and the filament width at 0.4 mm to prepare a 3D-printed magnesium-containing tricalcium phosphate / polycaprolactone artificial bone. Through cell experiments with the leaching solution, the cells grow well, and it has biocompatibility equivalent to that of the artificial bone repair body in Example 2 and no cytotoxicity.

[0080] Example 4: Preparation of an artificial bone repair body

[0081] Weighing and dissolving: Weigh 200 g of polycaprolactone and dissolve it in 4.0 kg of DMF reagent. Stir with a stirrer paddle at 400 rpm for 30 min until the solution is uniform. Weigh 20 g of the porous magnesium-containing tricalcium phosphate powder material prepared in Example 1 and dissolve it in 4.0 kg of DMF reagent. Stir with a stirrer paddle at 400 rpm for 30 min until the solution is uniform.

[0082] Mixing and preparing: Mix the solutions of magnesium-containing tricalcium phosphate and polycaprolactone, stir with a stirrer paddle at 400 rpm for 30 min until the solution is uniform, and then pour it into 100 L of pure water. White flocculent precipitates appear. Use a vacuum filter to filter to obtain polycaprolactone / magnesium-containing tricalcium phosphate composite fibers, and dry them in an oven at 60 °C for 12 hours.

[0083] Filament making: Use a screw extruder with the feeding temperature set at 90 °C and the process temperature controlled at 100 °C. Add the dried magnesium-containing tricalcium phosphate and polycaprolactone composite to the screw extruder, set the extruded filament diameter to 1.75 mm, and the filament-making speed to 1 m / min to obtain a filament for 3D printing.

[0084] 3D printing: Import the digital model, set the printing temperature at 150 °C, the printing speed at 10 mm / s, the filling rate at 50%, and the wire diameter width at 0.4 mm, and prepare a 3D-printed magnesium-containing tricalcium phosphate polycaprolactone artificial bone. After the cell experiment with the leaching solution, the cells grew well, and it had biocompatibility equivalent to that of the artificial bone repair body in Example 2 and no cytotoxicity.

[0085] The above artificial bone repair body based on 3D printing has the following characteristics:

[0086] (1) Connected pore structure

[0087] Manufacture a complex connected pore structure through the hot melt 3D printing technology. The material is flexible, and the composite material design overcomes the problems of traditional ceramic materials such as high brittleness and difficult processing. Compared with the existing bone filling materials, the artificial bone repair body of the present application can be customized individually, is easy to cut and process, and is convenient for doctors to shape during the operation. The 3D-printed porous artificial bone promotes the adhesion of osteoblasts and bone tissue deposition, and improves osteoconductivity and bioactivity. The interconnected pores inside the 3D-printed porous scaffold are beneficial to the growth of new bone, material transport, and vascularization.

[0088] (2) Degradation performance

[0089] The degradation product of polycaprolactone is neutral and not easily induces an inflammatory reaction. At the same time, when polycaprolactone is directly applied to bone tissue repair, its bioactivity is insufficient, and new bone tissue cannot form a tight osseous bond with the polymer scaffold. The present application uses a tricalcium phosphate material to compound polycaprolactone. Compared with the traditional hydroxyapatite material, tricalcium phosphate (β-TCP) has a similar chemical composition but better degradation performance. It can produce bioactive ions Ca 2+ and PO 4 3- ions through degradation. After tricalcium phosphate ceramic is implanted into the body, it can form a firm chemical bond with bone.

[0090] (3) No solvent residue problem in the internal mixer mechanical mixing method

[0091] The porous magnesium-containing tricalcium phosphate powder material of the present application has better fluidity in molten polycaprolactone. By mixing the porous magnesium-containing tricalcium phosphate powder material and polycaprolactone through the internal mixer mechanical mixing method, the mixing performance is improved, so that the mixing process can be completed by the internal mixer mechanical mixing method without adding organic solvents, avoiding the cytotoxicity caused by organic reagents.

[0092] (4) Problem of insufficient mechanical strength and bioactivity

[0093] By using the porous magnesium-containing tricalcium phosphate powder material, the mixing performance is improved, so that the mixing process can be completed by the internal mixer mechanical mixing method, significantly improving the mechanical strength and bioactivity of the material.

[0094] In addition, using a porous magnesium-containing tricalcium phosphate powder material as the main raw material has better bioactivity compared with traditional calcium phosphate materials. After the magnesium ions doped in the magnesium-containing tricalcium phosphate material are degraded and released in the body, they can induce osteoblast differentiation and osteogenic expression.

[0095] As shown in this specification and the claims, the terms "comprising" and "including" only imply the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements. The term "and / or" used herein includes any combination of one or more of the related listed items.

[0096] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0097] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. If there are contradictions or inconsistencies between the definitions used herein and those contained in other published documents, the definitions used herein shall prevail.

[0098] The above embodiments are only for illustrating the technical concept and features of the present invention, and are a preferred embodiment. The purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of an artificial bone repair body based on 3D printing, characterized in that, it includes the following steps: (1) Mix polycaprolactone and porous tricalcium phosphate powder materials evenly; (2) Make the mixed materials into solid printing raw materials; (3) According to a preset model, melt-print the artificial bone repair body with the solid printing raw materials through a 3D printer; wherein, the porous tricalcium phosphate powder material is formed by drying the precipitate after the reaction of the salt solution mixture, and the salt solution includes a calcium salt and a phosphate solution; The porous tricalcium phosphate powder material is prepared by the following steps: Prepare a first solution containing calcium ions; prepare a phosphate solution and adjust the pH to 9.5 - 10.5 with an alkali solution as the second solution; Heat and mix the first solution and the second solution, and react under the conditions of 60 - 95 °C and stirring; Centrifuge and separate the precipitate from the obtained suspension after the reaction, wash it, and spray-dry the washed precipitate to obtain the porous tricalcium phosphate powder material.

2. The preparation method according to claim 1, characterized in that, in step (1), the polycaprolactone and the porous tricalcium phosphate powder materials are mixed evenly by a mechanical method or a solvent dissolution method.

3. The preparation method according to claim 2, characterized in that, step (1) is specifically implemented as follows: Add polycaprolactone and porous tricalcium phosphate powder materials into a mixer and heat and mix them. The heating temperature is 30 - 200 °C, and the mixing time is 0.5 - 12 hours; put the obtained mixed materials into a granulator to crush them to form granular materials with a diameter of 0.1 - 10 mm; then add them into the mixer again and mix evenly. The heating temperature is 50 - 150 °C, and the mixing time is 0.5 - 12 hours to obtain a uniformly mixed polycaprolactone / porous tricalcium phosphate powder material composite.

4. The preparation method according to claim 2, characterized in that, step (1) is specifically implemented as follows: Dissolve polycaprolactone and porous tricalcium phosphate powder materials respectively with a solvent, stir evenly and then mix them, and then inject them into pure water; collect the precipitated precipitate by suction filtration, and dry it for 6 - 24 hours to obtain a uniformly mixed polycaprolactone / porous tricalcium phosphate powder material composite fiber; wherein, the solvent includes one or a combination of more of N,N-dimethylformamide (DMF), chloroform, acetone, toluene, and carbon tetrachloride. The mass ratio of the solid material to the solvent is 0.01 - 0.2, the volume ratio of the mixed solvent to pure water is 0.05 - 0.2, and the drying temperature is 30 - 100 °C.

5. The preparation method according to claim 1, characterized in that, the molecular weight of polycaprolactone is 50000 - 200000 Da, and the mass content of the porous tricalcium phosphate powder material in the materials mixed evenly in step (1) is less than 50%.

6. The preparation method according to claim 1, characterized in that, in step (2), the solid printing material is a wire material, and the wire material is made by a screw wire extruder. The temperature of the screw wire extruder is set at 60 - 130 °C, and the wire-making speed is 0.1 - 5 m / min.

7. The preparation method according to claim 1, characterized in that, in step (3), the parameters of the 3D printer are set as follows: the printing temperature is 120 - 250 °C, the printing speed is 5 - 70 mm / s, the filling rate is 20 - 100%, and the wire diameter width is 0.1 - 0.8 mm.

8. The preparation method according to claim 1, characterized in that, the porous tricalcium phosphate powder material is formed by spray-drying the precipitate, and its particle size is 1 - 20 μm.

9. The preparation method according to claim 1, characterized in that, the salt solution further includes a magnesium salt, and the porous tricalcium phosphate powder material contains 1 - 3% by mass of magnesium element.

10. The preparation method according to claim 1, characterized in that, the first solution further contains magnesium ions, and the molar ratio of calcium ions to magnesium ions in the first solution is 6 - 10; after the first solution and the second solution are mixed, the molar ratio of calcium ions to phosphate ions is 1.1 - 1.5; the calcium salt is selected from one or more combinations of anhydrous calcium chloride, calcium chloride dihydrate, and calcium nitrate tetrahydrate, the magnesium ions are from magnesium chloride hexahydrate and / or magnesium nitrate hexahydrate, the phosphate is selected from one or more combinations of disodium hydrogen phosphate, diammonium hydrogen phosphate, and sodium hydrogen phosphate, and the alkali solution is ammonia water or sodium hydroxide.

11. The preparation method according to claim 1, characterized in that, the washed precipitate is spray-dried using a spray dryer, and the inlet air temperature of the spray dryer is 240 - 300 °C, the outlet air temperature is 120 - 150 °C, and the feeding rate is 30 - 200 mL / min.

12. An artificial bone repair body based on 3D printing, characterized in that, it is prepared by the preparation method according to any one of claims 1 to 11.

13. The artificial bone repair body according to claim 12, characterized in that, the porosity of the artificial bone repair body is 30 - 70%, the maximum pore diameter is greater than 300 μm, and the mechanical strength is 2 - 20 MPa.

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