3D-printed antioxidant rare earth oxide-doped bone repair scaffold and method of making the same

Abstract

The application belongs to the field of bone repair, and particularly relates to a 3D printing antioxidant rare earth oxide doped bone repair scaffold and a preparation method thereof. The method comprises the following steps: taking PVA aqueous solution as a base, adding a dispersing agent ammonium polyacrylate to obtain an adhesive solution for nano powder; mixing nHAp, nβ-TCP and nREO through ball milling, and uniformly mixing the adhesive solution to prepare a 3D printable paste-like slurry; introducing a scaffold three-dimensional model, setting printing parameters, and using a pneumatic extrusion type 3D printing to obtain a scaffold blank; drying the scaffold blank at room temperature, and sintering at high temperature in an air atmosphere to obtain an organic component-free bone repair scaffold. The preparation method has few types of raw materials, and the preparation process is less affected by the environment. After adding rare earth oxides, the scaffold has good compressive strength, biocompatibility and antioxidant capacity, and can be used as a cell-carrying scaffold and a drug-carrying scaffold for biological 3D printing on the basis of being used for bone repair implantation, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of bone repair, specifically relating to a 3D-printed bone repair scaffold doped with antioxidant rare earth oxides, using hydroxyapatite, β-tricalcium phosphate and antioxidant rare earth metal nano-oxides as the main materials, and its preparation method. Background Technology

[0002] Nano-β-tricalcium phosphate (nβ-TCP) possesses excellent biodegradability, biocompatibility, and non-toxicity. When implanted in the human body, the degraded Ca and P can enter the circulatory system to form new bone, fusing directly with the bone without any local inflammatory reactions or systemic toxicity. Nano-hydroxyapatite (nHAp) is an inorganic ceramic material with the chemical formula Ca5(OH)(PO4)3, possessing an ultrastructure similar to human bone tissue. The particle size of nano-hydroxyapatite is typically between 1-100 nm, offering advantages such as easy slurry formation, easy solidification, and convenient processing. Literature indicates that because nHAp shares the same chemical composition as natural bone minerals, it can promote osteoblast adhesion and proliferation, making it the most widely used biomaterial in this field. Data shows that the compressive strength of human cancellous bone is approximately 2-20 MPa; therefore, artificial bone scaffolds mimicking human cancellous bone should possess similar mechanical properties. However, existing bone repair scaffolds still have significant technical limitations and application constraints. Bone repair materials with nβ-TCP or nHAp as the main components often struggle to simultaneously achieve optimal mechanical properties, degradation behavior, and bioactivity. While nβ-TCP exhibits good biodegradability, its compressive strength tends to decrease after constructing porous scaffolds, making it difficult to provide long-term, stable mechanical support that matches human cancellous bone. Although nHAp possesses good biocompatibility and osteoconductivity, it suffers from high brittleness and a slow degradation rate, hindering the dynamic matching between material degradation and new bone formation. Furthermore, existing techniques for improving the bone defect microenvironment by adding organic antioxidants or common inorganic functional components generally suffer from short-lasting antioxidant effects, insufficient stability, easy burst release, increased cytotoxicity risk, and limited promotion of osteogenic differentiation. Especially in the early stages of bone defect repair when inflammation and oxidative stress levels are high, existing bone repair scaffolds typically cannot simultaneously meet the four core requirements of mechanical matching with human cancellous bone, long-lasting antioxidant effects, low cytotoxicity, and high osteogenic differentiation, thus limiting their application in complex bone defect repair.

[0003] When bone tissue is damaged, excessive levels of reactive oxygen species (ROS) lead to oxidative stress, which promotes osteoclast formation, restricts osteoblast differentiation, and induces apoptosis. Considering that acute inflammation occurs in the first stage of fracture healing, and that the implant itself may also induce excessive inflammation, it is necessary to introduce bioactive materials with antioxidant capabilities that can eliminate excessive ROS, reduce adverse damage, and accelerate the bone repair process. Among rare earth metal oxides, several have antioxidant properties. Nano-cerium dioxide (nCeO2) is a rare earth oxide with unique redox properties, and its fluorite-type crystal structure contains variable-valence cerium ions (Ce... 4+ / Ce 3+ The presence of oxygen vacancies and other defects endows cerium dioxide with exceptional reactive oxygen species (ROS) scavenging capabilities and long-lasting antioxidant properties, making it a research hotspot in materials science and biomedicine. Nano-cerium dioxide (nCeO2) benefits from its larger surface area and higher CeO2 content. 4+ / Ce 3+ The ratio of [specific components] demonstrates a stronger ROS scavenging efficiency. nCeO2 nanoparticles can also promote osteoblast proliferation and osteogenic differentiation by promoting mineral deposition, alkaline phosphatase, and osteogenic gene expression in osteoblasts. Furthermore, nano-yttrium oxide (nY2O3) and nano-lanthanum oxide (nLa2O3) also possess bio-antioxidant functions and good biocompatibility. When combined with bioceramic materials, they can be used in bone repair, exhibiting good mechanical properties and osteogenic characteristics.

[0004] Three-dimensional (3D) structures with porous properties are well-suited for mimicking the characteristics of the extracellular matrix (ECM) and the porosity and interconnectivity of natural bone. These structures are more conducive to cell attachment and proliferation, and promote the continuous inward growth of new tissue. 3D printing technology can not only achieve porous 3D structures but also ensure that the scaffold possesses mechanical properties similar to human cancellous bone, simultaneously providing mechanical support and promoting new tissue growth, resulting in excellent bone regeneration. This invention integrates rare-earth oxide nanoparticles with antioxidant activity into a biphasic calcium phosphate nanoparticle powder composed of nano-hydroxyapatite (nHAp) and nano-β-tricalcium phosphate (nβ-TCP), and prepares a bone repair scaffold with good compressive strength, cell compatibility, and antioxidant properties through room temperature extrusion 3D printing. The incorporation of rare-earth oxide nanoparticles enhances both the mechanical properties and biocompatibility of the calcium phosphate scaffold. Because rare earth oxides such as nCeO2 have antioxidant activity, their antioxidant activity is much higher under alkaline conditions than under acidic conditions, and biphasic calcium phosphate makes the surrounding environment slightly alkaline during degradation in body fluids, which further enhances the repair capacity of the stent. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a 3D-printed bone repair scaffold doped with antioxidant rare earth oxides and its preparation method, achieving: uniform slurry dispersion, stable extrusion, and good formability; scaffold porosity of 38%–85% and compressive strength of 10–25 MPa, matching human cancellous bone; introduction of rare earth oxides to achieve long-term antioxidant effect, high biocompatibility, and promotion of osteogenic differentiation; simple process, environmentally friendly, and suitable for large-scale preparation.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for preparing a 3D-printed bone repair scaffold doped with antioxidant rare earth oxides includes the following steps:

[0008] Preparation of adhesive solution: Using polyvinyl alcohol (PVA) aqueous solution as the matrix, add ammonium polyacrylate dispersant to obtain an adhesive solution for nanopowders;

[0009] Preparation of printing paste: Nano-hydroxyapatite (nHAp), nano-β-tricalcium phosphate (nβ-TCP) and antioxidant rare earth oxide nanomaterials (nREO) are ball-milled and mixed with the binder solution to obtain a paste-like paste suitable for 3D printing;

[0010] 3D printing molding: Import the 3D model of the bracket, set the printing parameters, and use pneumatic extrusion 3D printing to obtain the bracket blank;

[0011] Drying and sintering: After the scaffold blank is dried at room temperature, it is sintered at high temperature in air to obtain a bone repair scaffold without organic components.

[0012] Furthermore, in the adhesive solution, the mass fraction of PVA is 10.0-15.0 wt%, and the mass fraction of ammonium polyacrylate is 0.5-2.0 wt%.

[0013] Furthermore, the antioxidant rare earth oxide nanomaterial is selected from one or more of nCeO2, nY2O3, and nLa2O3.

[0014] Furthermore, the mixed powder composition satisfies the following: the mass ratio of nHAp to nβ-TCP is 20.0–80.0 wt% : 80.0–20.0 wt%; nREO accounts for 5.0–20.0 wt% of the total mass of nHAp and nβ-TCP; and the mass fraction of the mixed nanoparticles in the final printing paste is 37.5–50.0 wt%.

[0015] Furthermore, the ball milling is a planetary ball mill with a ball-to-material ratio of 20:1–30:1, a rotation speed of 300–450 rpm, and a milling time of 4–12 h; the milling media is zirconium oxide.

[0016] Furthermore, the 3D printing parameters are as follows: printing needle diameter 0.5 mm; printing layer height 0.4–1.0 mm, line spacing 1.0–2.0 mm; interlayer routing angle 90°; extrusion pressure 0.2–0.6 MPa, platform temperature 25°C.

[0017] Furthermore, the drying process involves standing at 25°C and 40%–60% humidity for 12–48 hours.

[0018] Furthermore, the sintering conditions are as follows: heating / cooling rate 1.0–3.0℃ / min; maximum sintering temperature 1000–1200℃; holding time 3–5 h; and sintering atmosphere is air.

[0019] A 3D-printed bone repair scaffold doped with antioxidant rare earth oxides is prepared by the above method. The scaffold has a porous interconnected structure with a porosity of 38%–85% and a compressive strength of 10–25 MPa. It possesses antioxidant, cell compatibility and osteogenic differentiation promotion properties.

[0020] Furthermore, the nREO is one or more of nCeO2, nY2O3, and nLa2O3, and the amount added is 5.0–20.0 wt%; the scaffold has a porous interconnected structure and can be used for bone defect repair, cell printing, or drug-loaded scaffolds.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides a method for preparing a 3D-printed antioxidant rare-earth oxide-doped bone repair scaffold for bone repair, using nHAp, nβ-TCP, and nREO as the main materials. PVA aqueous solution is used as a binder for the nanoparticles, and an artificial bone cement slurry is prepared by ball milling. A cylindrical model with a porous structure is designed and imported into the 3D printer software. After printing using room temperature 3D printing technology, the scaffold is dried and sintered to obtain an artificial bone scaffold free of organic components. This preparation method requires fewer types of raw materials and the preparation process is less affected by the environment. With the addition of rare-earth oxides, the scaffold exhibits good compressive strength, biocompatibility, and antioxidant capacity. In addition to its use in bone repair implantation, it can also be used as a cell-carrying scaffold and drug-carrying scaffold for bio-3D printing, showing broad application prospects. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the fabrication process of the 3D-printed antioxidant nREO-doped nBCP scaffold of the present invention.

[0024] Figure 2Scanning electron microscope image of the bone scaffold (nCeO2 10wt%) prepared in Example 2 of the present invention;

[0025] Figure 3 EDS mapping results (elemental distribution of Ca, P, and Ce) of the bone scaffold (nCeO2 10wt%) prepared in Example 2 of the present invention.

[0026] Figure 4 The results of the compressive strength test of the stent (force-deformation curve);

[0027] Figure 5 The results of the stent's ROS removal capability test;

[0028] Figure 6 Results of live / dead staining test;

[0029] Figure 7-1 and Figure 7-2 Microscopic images and quantitative statistical graphs of alkaline phosphatase (ALP) staining results of MC3T3-E1 cells co-cultured with scaffolds for 14 days;

[0030] Figure 8-1 and Figure 8-2 Microscopic images and quantitative statistical graphs of Alizarin Red (ARS) staining results of MC3T3-E1 cells co-cultured with scaffolds for 28 days. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments:

[0032] This invention discloses a method for preparing a 3D-printed bone repair scaffold doped with antioxidant rare earth oxides, such as... Figure 1 As shown, it includes the following steps:

[0033] Preparation of the adhesive solution: Using polyvinyl alcohol (PVA) aqueous solution as the matrix, ammonium polyacrylate dispersant is added to obtain an adhesive solution for nanoparticles. In this invention, PVA powder (10.0-15.0 wt%) and deionized water are weighed and placed in a beaker, sealed with plastic wrap, and the oil bath temperature is set to 80-90℃. The mixture is then magnetically stirred for 1-2 hours. The oil bath temperature is then lowered to 60℃, while maintaining the stirring speed, until the solution is homogeneous and transparent. After returning to room temperature, ammonium polyacrylate dispersant solution (0.5-2.0 wt%) is added and stirred, ultimately yielding a colorless, homogeneous, and transparent solution.

[0034] Preparation of printing paste: Nano-hydroxyapatite (nHAp), nano-β-tricalcium phosphate (nβ-TCP), and antioxidant rare earth oxide nanomaterials (nREO) are ball-milled and mixed with a binder solution to obtain a paste-like paste suitable for 3D printing. The nREO is selected from one or more of nano-cerium dioxide (nCeO2), nano-yttrium oxide (nY2O3), and nano-lanthanum oxide (nLa2O3).

[0035] Specifically, nHAp and nβ-TCP are mixed using a planetary ball mill to form nBCP powder, with the mass fractions of the two nanoparticles being 20.0-80.0 wt% nHAp and 80.0-20.0 wt% nβ-TCP. The nHAp and nβ-TCP are then mixed to form a pre-dispersed powder, and nREO powder is added and mixed evenly using a planetary ball mill, with the nREO powder accounting for 5.0-20.0 wt% of the mixed powder. The mixed powder is slowly added to the binder solution and stirred until the slurry is homogeneous. Ultrasonic degassing is then performed to obtain a uniform, extrudable, and formable paste-like printing slurry. The ultrasonic power is 80W, the time is 5-10 minutes, and the temperature is maintained at 25-30℃. The mass fraction of the mixed nanoparticles in the final printing slurry is 37.5-50.0 wt%.

[0036] 3D Printing: Import the 3D model of the support frame, set the printing parameters, and use pneumatic extrusion 3D printing to obtain the support frame blank. Specifically, import the printing model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.4-0.6mm, the line spacing to 1.0-1.5mm, and the printing structure to a line angle of 90°. Adjust the output speed to continuously and uniformly extrude the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the final model is printed. The printer extrusion air pressure can be set to 0.2-0.6MPa, the platform temperature to 25℃, and the printed model to be a cylinder with a base diameter of 4mm and a height of 8mm.

[0037] Sample drying and sintering: After drying the scaffold blank at room temperature, it was sintered at high temperature in air to obtain a bone repair scaffold without organic components. The drying process involved placing the printed samples in a room temperature environment (25℃, 40%-60%) for 12-48 hours.

[0038] Sintering conditions: The completely dried scaffold is placed in a corundum crucible. The sintering atmosphere is air. During the sintering process, the heating and cooling rates are 1.0-3.0℃ / h. The maximum sintering temperature is 1000℃-1200℃. The holding time is 3-5h. Then, the temperature is lowered to room temperature at the same rate. After sintering, the final bone scaffold is obtained.

[0039] Example 1:

[0040] Preparation of adhesive solution: Weigh 1g of PVA powder (10% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 80℃, and stir magnetically for 1h; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 0.5wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0041] Preparation of printing paste: Weigh 1.71g nHAp, 3.99g nβ-TCP, and 0.3g nCeO2 (total 6g, nHAp to nβ-TCP mass ratio of 3:7, nCeO2 mass fraction of 5%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0042] 3D Printing: Import the model into the printing software, select a suitable print head, set the layer height to 0.4mm, the line spacing to 1.0mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the print head moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.2MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0043] Sample drying: Place the printed sample in a room temperature environment for 12 hours (25°C, 40% humidity).

[0044] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1000℃ at a rate of 2.5℃ / h and held for 3 hours. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0045] Example 2:

[0046] Preparation of adhesive solution: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 85℃, and stir magnetically for 2 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 1.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0047] Preparation of printing paste: Weigh 4.32g nHAp, 2.88g nβ-TCP, and 0.8g nCeO2 (total 8g, nHAp to nβ-TCP mass ratio of 6:4, nCeO2 mass fraction 10%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0048] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.5mm, the line spacing to 1.2mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.4MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0049] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0050] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0051] Example 3:

[0052] Preparation of adhesive solution: Weigh 1.5g of PVA powder (15% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 90℃, and stir magnetically for 3h; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 2.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0053] Preparation of printing paste: Weigh 5.6g nHAp, 2.4g nβ-TCP, and 2g nCeO2 (total 10g, nHAp to nβ-TCP mass ratio of 7:3, nCeO2 mass fraction 20%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0054] 3D Printing: Import the model into the printing software, select a suitable print head, set the layer height to 0.6mm, the line spacing to 1.5mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the print head moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.6MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0055] Sample drying: Place the printed sample in a room temperature environment for 48 hours (25°C, 60% humidity).

[0056] Sample sintering: The completely dried scaffold was placed in a corundum crucible and sintered in air. The temperature was increased to 1200℃ at a rate of 3℃ / h and held for 5h. Then, the temperature was reduced to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0057] Example 4:

[0058] Preparation of adhesive solution: Weigh 1g of PVA powder (10% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 80℃, and stir magnetically for 1h; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 0.5wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0059] Preparation of printing paste: Weigh 1.17g nHAp, 3.99g nβ-TCP, and 0.3g nY2O3 (total 6g, nHAp to nβ-TCP mass ratio of 3:7, nY2O3 mass fraction of 5%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0060] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.4mm, the line spacing to 1.0mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.2MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0061] Sample drying: Place the printed sample in a room temperature environment for 12 hours (25°C, 40% humidity).

[0062] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1000℃ at a rate of 2.5℃ / h and held for 3 hours. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0063] Example 5:

[0064] Preparation of adhesive solution: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 85℃, and stir magnetically for 2 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 1.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0065] Preparation of printing paste: Weigh 4.32g nHAp, 2.88g nβ-TCP, and 0.8g nY2O3 (total 8g, nHAp to nβ-TCP mass ratio of 6:4, nY2O3 mass fraction 10%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0066] 3D Printing: Import the model into the printing software, select a suitable print head, set the layer height to 0.5mm, the line spacing to 1.2mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the print head moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.4MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0067] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0068] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0069] Example 6:

[0070] Preparation of adhesive solution: Weigh 1.5g of PVA powder (15% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 90℃, and stir magnetically for 3 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 2.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0071] Preparation of printing paste: Weigh 5.6g nHAp, 2.4g nβ-TCP, and 2g nY2O3 (total 10g, nHAp to nβ-TCP mass ratio of 7:3, nY2O3 mass fraction 20%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0072] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.6mm, the line spacing to 1.5mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.6MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0073] Sample drying: Place the printed sample in a room temperature environment for 48 hours (25°C, 60% humidity).

[0074] Sample sintering: The completely dried scaffold was placed in a corundum crucible and sintered in air. The temperature was increased to 1200℃ at a rate of 3℃ / h and held for 5h. Then, the temperature was reduced to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0075] Example 7:

[0076] Preparation of adhesive solution: Weigh 1g of PVA powder (10% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 80℃, and stir magnetically for 1h; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 0.5wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0077] Preparation of printing paste: Weigh 1.17g nHAp, 3.99g nβ-TCP, and 0.3g nLa2O3 (total 6g, nHAp to nβ-TCP mass ratio 3:7, nLa2O3 mass fraction 5%), and mix them evenly using a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing to obtain a uniform printing paste with good extrudability and formability. The printer extrusion pressure is set to 0.2MPa, the platform temperature is 25℃, and the printing model is a cylinder with a bottom diameter of 4mm and a height of 8mm.

[0078] 3D Printing Process: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.4mm, the line spacing to 1.0mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the final model is printed.

[0079] Sample drying: Place the printed sample in a room temperature environment for 12 hours (25°C, 40% humidity).

[0080] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1000℃ at a rate of 2.5℃ / h and held for 3 hours. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0081] Example 8:

[0082] Preparation of adhesive solution: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 85℃, and stir magnetically for 2 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 1.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0083] Preparation of printing paste: Weigh 4.32g nHAp, 2.88g nβ-TCP, and 0.8g nLa2O3 (total 8g, nHAp to nβ-TCP mass ratio of 6:4, nLa2O3 mass fraction 10%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0084] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.5mm, the line spacing to 1.2mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.4MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0085] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0086] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0087] Example 9:

[0088] Preparation of adhesive solution: Weigh 1.5g of PVA powder (15% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 90℃, and stir magnetically for 3 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 2.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0089] Preparation of printing paste: Weigh 5.6g nHAp, 2.4g nβ-TCP, and 2g nLa2O3 (total 10g, nHAp to nβ-TCP mass ratio of 7:3, nLa2O3 mass fraction 20%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0090] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.6mm, the line spacing to 1.5mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.6MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0091] Sample drying: Place the printed sample in a room temperature environment for 48 hours (25°C, 60% humidity).

[0092] Sample sintering: The completely dried scaffold was placed in a corundum crucible and sintered in air. The temperature was increased to 1200℃ at a rate of 3℃ / h and held for 5h. Then, the temperature was reduced to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0093] Example 10:

[0094] Preparation of adhesive solution: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 85℃, and stir magnetically for 2 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 1.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0095] Preparation of printing paste: Weigh 1.71g nHAp, 3.99g nβ-TCP, and 0.3g nREO (total 8g, nHAp to nβ-TCP mass ratio of 6:4, nREO mass fraction of 10%, including 0.15g nCeO2, 0.075g nY2O3, and 0.075g nLa2O3), mix them evenly with a planetary ball mill, and gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0096] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.5mm, the line spacing to 1.2mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.4MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0097] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0098] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0099] Example 11:

[0100] Preparation of adhesive solution: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 85℃, and stir magnetically for 2 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 1.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0101] Preparation of printing paste: Weigh 4.32g nHAp, 2.88g nβ-TCP, and 0.8g nREO (total 8g, nHAp to nβ-TCP mass ratio is 6:4, nCeO2 mass fraction is 10%, including 0.4g nCeO2, 0.2g nY2O3, and 0.2g nLa2O3), mix them evenly with a planetary ball mill, and gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0102] 3D Printing: Import the model into the printing software, select a 0.5mm diameter printing nozzle, set the layer height to 0.5mm, the line spacing to 1.2mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the printing nozzle moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.4MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0103] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0104] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0105] Example 12:

[0106] Preparation of adhesive solution: Weigh 1.5g of PVA powder (15% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 90℃, and stir magnetically for 3h; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 2.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0107] Preparation of printing paste: Weigh 5.6g nHAp, 2.4g nβ-TCP, and 2g nREO (total 10g, nHAp to nβ-TCP mass ratio of 7:3, nCeO2 mass fraction of 20%, including 1g nCeO2, 0.5g nY2O3, and 0.5g nLa2O3) of three nanoparticles, mix them evenly with a planetary ball mill, and gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0108] 3D Printing: Import the model into the printing software, select a suitable print head, set the layer height to 0.6mm, the line spacing to 1.5mm, and the line angle to 90°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the print head moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion pressure is set to 0.6MPa, the platform temperature to 25℃, and the printed model is a cylinder with a base diameter of 4mm and a height of 8mm.

[0109] Sample drying: Place the printed sample in a room temperature environment for 48 hours (25°C, 60% humidity).

[0110] Sample sintering: The completely dried scaffold was placed in a corundum crucible and sintered in air. The temperature was increased to 1200℃ at a rate of 3℃ / h and held for 5h. Then, the temperature was reduced to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0111] Comparative Example 1 (Pure nBCP stent):

[0112] Adhesive preparation: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 90℃, and stir magnetically for 3 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 2.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0113] 3D printing paste preparation: Weigh 7g of nHAp and 3g of nβ-TCP (total 10g, nHAp to nβ-TCP mass ratio 7:3), mix them evenly using a planetary ball mill, and gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing to obtain a uniform printing paste with good extrudability and formability. The printer extrusion pressure is set to 0.4MPa, the platform temperature is 25℃, and the printed model is a cylinder with a bottom diameter of 4mm and a height of 8mm.

[0114] Set printing parameters: Import the print model into the printing software, select a 0.5mm diameter print head, set the layer height to 0.5mm, the line spacing to 1.2mm, and the print structure to a line angle of 90°. Adjust the output speed to ensure continuous and uniform extrusion of the print material. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the print head moves along the z axis, printing layer by layer until the specified model is completed.

[0115] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0116] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0117] Comparative Example 2 (printed structure with a line angle of 60°):

[0118] Adhesive preparation: Weigh 1.3g of PVA powder (13% PVA by mass) and 10mL of deionized water into a beaker, seal with plastic wrap, set the oil bath temperature to 85℃, and stir magnetically for 2 hours; then lower the oil bath temperature to 60℃, keep the speed constant, and stir until the solution is homogeneous and transparent. After returning to room temperature, add 1.0wt% dispersant ammonium polyacrylate solution and stir to finally obtain a colorless, homogeneous, and transparent solution.

[0119] 3D printing paste preparation: Weigh 4.32g nHAp, 2.88g nβ-TCP, and 0.8g nCeO2 (total 8g, nHAp to nβ-TCP mass ratio of 6:4, nCeO2 mass fraction 10%) and mix them evenly with a planetary ball mill. Gradually and slowly add the mixed powder to the binder solution while stirring. After stirring evenly, perform ultrasonic degassing treatment to obtain a uniform printing paste with good extrudability and formability.

[0120] Set printing parameters: Import the print model into the printing software, select a 0.5mm diameter print head, set the print layer height to 0.5mm, the line spacing to 1.2mm, and the print structure to a line angle of 60°. Adjust the output speed to ensure continuous and uniform extrusion of the slurry. The printer uses pneumatic extrusion; the worktable moves along the x and y axes, while the print head moves along the z axis, printing layer by layer until the specified model is completed. The printer extrusion air pressure is set to 0.4MPa, the platform temperature to 25℃, and the print model to be a cylinder with a base diameter of 4mm and a height of 8mm.

[0121] Sample drying: Place the printed sample in a room temperature environment for 24 hours (25°C, 50% humidity).

[0122] Sample sintering: The completely dried scaffold was placed in a corundum crucible, and the sintering atmosphere was air. The temperature was raised to 1150℃ at a rate of 2℃ / h and held for 4h. Then, the temperature was lowered to room temperature at the same rate. After sintering, the final artificial bone scaffold was obtained.

[0123] Characterization and performance testing of the finished stent in the embodiments:

[0124] The scaffold sample prepared in Example 2 was used to characterize its microstructure and elemental distribution using scanning electron microscopy (e.g., Figure 2 The SEM image (as shown) reveals micropores on the scaffold surface, which are more conducive to cell adhesion and growth. EDS mapping results (as shown) Figure 3 As shown, the support exhibits a uniform elemental distribution. Its porosity, compressive strength, and dimensional shrinkage before and after sintering were tested using the following methods: Porosity was tested using the liquid-phase displacement method. Anhydrous ethanol of volume V1 was injected into a graduated cylinder. The sample was slowly immersed for 10 minutes, and the ethanol volume V2 was recorded at this point. The sample was then removed and the ethanol volume V3 was recorded. The porosity was calculated using the following formula:

[0125]

[0126] Calculations showed that the average porosity of samples in Examples 1-12 was between 38% and 85%, a range conducive to the transport of blood and nutrients. Compressive strength was tested using a universal testing machine (e.g., Figure 4 As shown in the figure, the compressive strength of the pure nBCP sample scaffold from Comparative Example 1 and the sample scaffolds with 5wt%, 10wt%, and 20wt% nCeO2 added in Examples 1-3 were tested. The average maximum compressive strengths were 5.635 MPa, 13.406 MPa, 24.830 MPa, and 15.568 MPa, respectively. This indicates that the scaffold samples prepared by this process with the addition of rare earth oxides have stable structures and sufficient mechanical properties, which are significantly better than those of pure nBCP scaffolds. They have compressive strength similar to that of human cancellous bone, which can ensure stability during implantation. The addition of rare earth oxides can improve the mechanical properties of the scaffold. Within a certain range, the compressive strength of the scaffold increases with the increase of cerium dioxide content. However, excessive addition of rare earth oxides will lead to a decrease in the mechanical properties of the scaffold, but overall, they can meet the compressive strength range of human cancellous bone. It is worth noting that porosity and maximum compressive strength tests were performed on the scaffold samples in Comparative Example 2. The test results showed that the average porosity of the scaffold sample with a 60° line angle was 15%-31%, and the average maximum compressive strength was 25.935 MPa. Although the maximum compressive strength was slightly higher than that of the 90° line angle structure, the scaffold porosity was too small, which is beneficial for the transport of blood and nutrients. The shrinkage rate of the samples before and after sintering was tested. After sintering, the shrinkage rate of the bottom diameter of the sample was approximately 27.7%, and the shrinkage rate of the height was approximately 20.6%. The pure nBCP sample scaffold from Comparative Example 1 and the sample scaffolds with 5 wt%, 10 wt%, and 20 wt% nREO added in Examples 10-12 were selected for ROS scavenging experiments and live / dead cell staining experiments (e.g., Figure 5 , Figure 6As shown in the figure), the ROS scavenging assay results showed that the scaffold samples with added rare earth oxides had good antioxidant capacity. The live / dead cell staining assay indicated that the scaffold samples generally had good biocompatibility. The antioxidant capacity and cell compatibility of the scaffold with 10 wt% rare earth oxides were significantly better than those of the pure nBCP scaffold. However, cell compatibility decreased when the addition amount was 20 wt%, indicating that excessive addition of rare earth oxides would enhance the cytotoxicity of the scaffold. MC3T3-E1 cells were co-cultured with the pure nBCP scaffold sample from Comparative Example 1 and the scaffold samples with 5 wt% and 10 wt% nREO added in Examples 10-12, respectively. Alkaline phosphatase (ALP) staining and Alizarin Red (ARS) staining were performed at 14 and 28 days (e.g., ...). Figure 7-1 , Figure 7-2 , Figure 8-1 and Figure 8-2 As shown in the figure, both qualitative and quantitative results indicate that the scaffold with a rare earth oxide content of 10 wt% significantly enhances the ability to promote osteogenic differentiation compared to the pure nBCP scaffold. The above experimental characterization results demonstrate that the bone repair scaffold prepared according to the method of this invention exhibits significantly improved performance compared to the traditional nBCP bone repair scaffold, providing a novel and effective solution for achieving better bone repair results.

[0127] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing 3D-printed bone repair scaffolds doped with antioxidant rare earth oxides, characterized in that, Includes the following steps: Preparation of adhesive solution: Using PVA aqueous solution as the base, add dispersant ammonium polyacrylate to obtain an adhesive solution for nanopowders; Preparation of printing paste: nHAp, nβ-TCP and nREO are ball-milled and mixed, and then mixed with the binder solution to obtain a paste-like paste suitable for 3D printing; 3D printing molding: Import the 3D model of the bracket, set the printing parameters, and use pneumatic extrusion 3D printing to obtain the bracket blank; Drying and sintering: After the scaffold blank is dried at room temperature, it is sintered at high temperature in air to obtain a bone repair scaffold without organic components.

2. The preparation method according to claim 1, characterized in that, The adhesive solution contains 10.0-15.0 wt% PVA and 0.5-2.0 wt% ammonium polyacrylate.

3. The preparation method according to claim 1, characterized in that, The nREO is selected from one or more of nCeO2, nY2O3, and nLa2O3.

4. The preparation method according to claim 1, characterized in that, The mixed powder composition satisfies the following: the mass ratio of nHAp to nβ-TCP is 20.0–80.0 wt% : 80.0–20.0 wt%; nREO accounts for 5.0–20.0 wt% of the total mass of nHAp and nβ-TCP; and the mass fraction of the mixed nanoparticles in the final printing paste is 37.5–50.0 wt%.

5. The preparation method according to claim 1, characterized in that, The ball milling is a planetary ball mill with a ball-to-material ratio of 20:1–30:1, a rotation speed of 300–450 rpm, and a milling time of 4–12 h; the milling media is zirconium oxide.

6. The preparation method according to claim 1, characterized in that, The 3D printing parameters are as follows: printing needle diameter 0.5 mm; layer height 0.4–1.0 mm, line spacing 1.0–2.0 mm; interlayer line angle 90°; extrusion pressure 0.2–0.6 MPa, platform temperature 25°C.

7. The preparation method according to claim 1, characterized in that, The drying process is as follows: let it stand for 12–48 hours at 25℃ and 40%–60% humidity.

8. The preparation method according to claim 1, characterized in that, The sintering conditions are as follows: heating / cooling rate 1.0–3.0℃ / min; maximum sintering temperature 1000–1200℃; holding time 3–5 h; sintering atmosphere is air.

9. A 3D-printed bone repair scaffold doped with antioxidant rare earth oxides, characterized in that... The scaffold is prepared by the method described in any one of claims 1–8; the scaffold has a porosity of 38%–85%, a compressive strength of 10–25 MPa, and possesses antioxidant, cell compatibility, and osteogenic differentiation promotion properties.

10. The bone repair scaffold according to claim 9, characterized in that, The nREO is one or more of nCeO2, nY2O3, and nLa2O3, and the amount added is 5.0–20.0 wt%; the scaffold has a porous interconnected structure and can be used for bone defect repair, cell printing, or drug-loaded scaffolds.

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