Photosensitive ceramic slurry, photocuring 3D printing biological ceramic material and preparation method and application of photocuring 3D printing biological ceramic material

Abstract

The invention provides photosensitive ceramic slurry and a photocuring 3D printing biological ceramic material as well as a preparation method and application thereof, and belongs to the technical field of medical biological materials. The photosensitive ceramic slurry provided by the invention is prepared from the following components in parts by mass: 50 to 55 parts of aluminum dihydrogen phosphate sol, 20 to 25 parts of ceramic powder, 10 to 15 parts of monomer, 0.05 to 0.10 part of photoinitiator, 0.01 to 0.05 part of stabilizer, 0.01 to 0.05 part of dye and 5 to 10 parts of water. A precursor obtained after 3D printing of the photosensitive ceramic slurry provided by the invention has the characteristics of free compression recovery, cutting and individualized filling of bone defect parts, flaws appearing in the printing process can be trimmed, and the precursor structure obtained after printing can be automatically recovered when slightly deformed; the problems that after 3D printing, the photosensitive resin is fixed in structure and cannot be freely compressed and cut are solved.

Description

Technical Field

[0001] This invention relates to the field of medical biomaterials technology, and in particular to photosensitive ceramic slurry and photocurable 3D printed bioceramic materials, their preparation methods and applications. Background Technology

[0002] With the increasing incidence of traffic accidents and bone tumors, large bone defects have become a challenging clinical problem, severely impacting patients' quality of life. Treatment strategies for large bone defects include autologous bone grafting and allogeneic bone grafting. Autologous bone has good biocompatibility and no risk of disease metastasis, but its application is limited due to insufficient availability and donor site-related complications. Allogeneic bone is relatively easy to obtain, but faces challenges such as immune rejection, infection, and ethical issues. Therefore, developing suitable artificial bone to replace autologous and allogeneic bone is urgently needed.

[0003] 3D-printed medical bioceramics have been widely explored as alternative materials for artificial bone engineering. Traditional photopolymer 3D-printed bioceramic materials are based on the manufacture of three-dimensional ceramic materials using photosensitive resin. However, after 3D printing photosensitive resin, the resulting precursor has high hardness and a fixed structure, which cannot be freely compressed or cut. Once printing defects or structural deformation occur, the printing process must be repeated. Therefore, the application of photosensitive resin 3D-printed bioceramic materials as alternatives to autologous and allogeneic bone has been limited. Summary of the Invention

[0004] The purpose of this invention is to provide a photosensitive ceramic slurry and a photocurable 3D printing bioceramic material, as well as their preparation method and application. The precursor obtained by 3D printing the photosensitive ceramic slurry provided by this invention is a flexible material that can be restored after compression and can be cut.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a photosensitive ceramic slurry, comprising the following components by mass parts: 50-55 parts aluminum dihydrogen phosphate sol, 20-25 parts ceramic powder, 10-15 parts monomer, 0.05-0.10 parts photoinitiator, 0.01-0.05 parts stabilizer, 0.01-0.05 parts dye, and 5-10 parts water.

[0006] Preferably, the preparation method of the aluminum dihydrogen phosphate sol includes the following steps: mixing phosphoric acid with Al(OH)3 powder and reacting to obtain the aluminum dihydrogen phosphate sol; the concentration of the phosphoric acid is 55~65wt%; the mass ratio of the phosphoric acid to the Al(OH)3 powder is 196:30~35; the reaction temperature is 95~105℃ and the time is 2~4h.

[0007] Preferably, the ceramic powder comprises one or more of hydroxyapatite, β-tricalcium phosphate, and calcium silicate; the particle size of the ceramic powder is 60-80 nm.

[0008] Preferably, the monomers include acrylic acid, acrylamide, and polyvinyl alcohol diacrylate; the mass ratio of acrylic acid, acrylamide, and polyvinyl alcohol diacrylate is 12~13:138~139:1~2.

[0009] Preferably, the photoinitiator is lithium phenyl-2,4,6-trimethylbenzoylphosphinic acid; the stabilizer is an acrylic acid polymerization inhibitor; and the dye is lemon yellow.

[0010] This invention provides a photopolymerizable 3D printing bioceramic material, the raw material of which is the photosensitive ceramic slurry described in the above technical solution.

[0011] This invention provides a method for preparing the photopolymerizable 3D printed bioceramic material described above, comprising the following steps: The photosensitive ceramic slurry was sequentially subjected to photocuring 3D printing, drying, and sintering to obtain the photocuring 3D printed bioceramic material.

[0012] Preferably, the conditions for photopolymerization 3D printing include: using an ultraviolet light source; and an initial exposure intensity of 38~42 mW / cm². 2 The exposure time is 10-20 seconds; the exposure intensity for the remaining layers is 18-22 mW / cm². 2 The exposure time is 5-10 seconds; The drying process includes sequentially performing a first drying, a second drying, and a third drying; the temperature of the first drying is 20~30℃, and the time is 6~8 days; the temperature of the second drying is 50~60℃, and the time is 6~8 days; the temperature of the third drying is 95~105℃, and the time is 6~8 days. The sintering process includes a first sintering and a second sintering in sequence; the temperature of the first sintering is 450~550℃ and the holding time is 4~6h; the temperature of the second sintering is 1100~1300℃ and the holding time is 2~4h.

[0013] This invention provides the application of the photocurable 3D printed bioceramic material described in the above technical solution or the photocurable 3D printed bioceramic material prepared by the preparation method described in the above technical solution in the preparation of materials that promote bone regeneration.

[0014] This invention provides the application of the photocurable 3D printed bioceramic material described in the above technical solution or the photocurable 3D printed bioceramic material prepared by the preparation method described in the above technical solution in the preparation of cranial repair scaffolds.

[0015] This invention provides a photosensitive ceramic slurry, comprising the following components by weight: 50-55 parts aluminum dihydrogen phosphate sol, 20-25 parts ceramic powder, 10-15 parts monomer, 0.05-0.10 parts photoinitiator, 0.01-0.05 parts stabilizer, 0.01-0.05 parts dye, and 5-10 parts water. The precursor obtained by 3D printing using the photosensitive ceramic slurry provided by this invention features free compression recovery, trimming, and individualized filling of bone defects. Imperfections occurring during the printing process can be trimmed, and slight deformations in the resulting precursor structure can self-recover, avoiding the problems of fixed structure, inability to freely compress, and trimming inherent in photosensitive resins after 3D printing.

[0016] Furthermore, photosensitive resin 3D printing of bioceramics suffers from high shrinkage rates (>20%) and the generation of greenhouse gases and harmful gases during sintering. The photocurable 3D printing bioceramic material prepared using the photosensitive ceramic slurry described in this invention has a shrinkage rate of 8-12%, significantly lower than that of photosensitive resin 3D printing bioceramics, making it more suitable for bone defect sites after sintering. Moreover, the aluminum dihydrogen phosphate sol in this invention only emits water vapor during sintering, reducing greenhouse gas and harmful gas emissions from the decomposition of photosensitive resin, making it more environmentally friendly.

[0017] The photopolymerizable 3D printing bioceramic material prepared using the photosensitive ceramic slurry described in this invention has good cell adhesion ability, can promote osteogenic differentiation of pre-osteoblasts MC3T3-E1 and repair of skull defects, and can be used to prepare skull repair scaffolds, with excellent prospects for promotion and application. Attached Figure Description

[0018] Figure 1 This is a flowchart and feature illustration of the fabrication process of the porous bioceramic scaffold in this embodiment of the invention; Figure 2 The images show actual photos of the porous bioceramic scaffold obtained after greening and sintering in Example 1, as well as scanning electron microscope images of the surface and cross-sectional pores of the porous bioceramic scaffold. Figure 3 The image shows the nanoindentation test results of the bioceramic scaffold prepared in Test Example 3; Figure 4 SEM images of cell adhesion on the surface of the porous bioceramic scaffold after 3 and 7 days of culture in Test Example 4; Figure 5 The experimental results and statistical results of alkaline phosphatase staining and alizarin red S staining in the material group and control group of test example 5 are shown in the figure. Figure 6 Morphological observation and micro-CT scan images of the healing of skull defects in SD rats in the material group and control group of test case 6; Figure 7H&E and Masson staining images of tissue sections from the material group and control group of SD rats in test case 6, showing the repair of skull defects. Figure 8 The images show the freshly prepared photosensitive ceramic slurry (0 min) and the photos taken after 30 min of standing in the experimental and control groups in Test Example 7. Figure 9 The images show the bioceramic scaffolds prepared for the experimental and control groups in Test Example 7. Detailed Implementation

[0019] This invention provides a photosensitive ceramic slurry, comprising the following components by mass parts: 50-55 parts aluminum dihydrogen phosphate sol, 20-25 parts ceramic powder, 10-15 parts monomer, 0.05-0.10 parts photoinitiator, 0.01-0.05 parts stabilizer, 0.01-0.05 parts dye, and 5-10 parts water.

[0020] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0021] The photosensitive ceramic slurry of the present invention comprises 50-55 parts by weight of aluminum dihydrogen phosphate sol, specifically 50, 51, 52, 53, 53.69, 54, or 55 parts. As one embodiment of the present invention, the preparation method of the aluminum dihydrogen phosphate sol includes the following steps: mixing phosphoric acid with Al(OH)3 powder and reacting to obtain the aluminum dihydrogen phosphate sol. As one embodiment of the present invention, the concentration of phosphoric acid can be 55-65 wt%, specifically 60 wt%; the mass ratio of phosphoric acid to Al(OH)3 powder can be 196:30-35, specifically 196:31.84; the reaction temperature can be 95-105℃, specifically 100℃; the reaction time can be 2-4 hours, specifically 3 hours; the reaction is preferably carried out under stirring conditions. The aluminum dihydrogen phosphate sol described in this invention serves as an inorganic binder. After sintering, it can act as a skeleton to fill the structure of ceramic materials, which helps to improve the hardness and mechanical properties of ceramic materials, thereby reducing the cracking problem of ceramic materials during sintering. Without the addition of aluminum dihydrogen phosphate sol, the sintered ceramic materials are brittle and prone to cracking.

[0022] Based on the mass fraction of the aluminum dihydrogen phosphate sol, the photosensitive ceramic slurry of this invention comprises 20-25 parts of ceramic powder, specifically 20, 21, 22, 23, 23.27, 24, or 25 parts. In one embodiment of this invention, the ceramic powder may include one or more of hydroxyapatite, β-tricalcium phosphate, and calcium silicate, specifically hydroxyapatite; the particle size of the ceramic powder may be 60-80 nm. The ceramic powder of this invention can release calcium ions, which is beneficial for promoting osteogenic differentiation and new bone formation.

[0023] Based on the mass fraction of the aluminum dihydrogen phosphate sol, the photosensitive ceramic slurry of this invention comprises 10-15 parts of monomer, specifically 10, 11, 12, 13, 13.64, 14, or 15 parts. In one embodiment of this invention, the monomer comprises acrylic acid, acrylamide, and polyvinyl alcohol diacrylate; the polyvinyl alcohol diacrylate (PEGDA) specifically may be PEGDA750; the mass ratio of acrylic acid, acrylamide, and polyvinyl alcohol diacrylate may be 12-13:138-139:1-2, specifically 12.48:138.60:1.36. The monomer of this invention forms a polymer compound with a cross-linked network through a polymerization reaction, and this cross-linked network plays a skeletal role in the precursor formed by photopolymerization 3D printing.

[0024] Based on the mass fraction of the aluminum dihydrogen phosphate sol, the photosensitive ceramic slurry of the present invention includes 0.05 to 0.10 parts of photoinitiator, specifically 0.05, 0.06, 0.07, 0.08, 0.09, or 0.10 parts. In one embodiment of the present invention, the photoinitiator may be lithium phenyl-2,4,6-trimethylbenzoylphosphinic acid (LAP). The present invention uses lithium phenyl-2,4,6-trimethylbenzoylphosphinic acid as a photoinitiator, which can absorb energy of a certain wavelength in the range of 365 to 405 nm, generating free radicals, cations, etc., thereby initiating the polymerization reaction of monomers to form a polymer compound with a cross-linked network.

[0025] Based on the mass fraction of the aluminum dihydrogen phosphate sol, the photosensitive ceramic slurry of this invention includes 0.01 to 0.05 parts of stabilizer, specifically 0.01, 0.02, 0.03, 0.04, or 0.05 parts. In one embodiment of this invention, the stabilizer can be an acrylic acid polymerization inhibitor, specifically 4-methoxyphenol. The stabilizer of this invention can slow down the polymerization reaction of monomers, increase the stability of the photosensitive ceramic slurry, and thus help ensure that the prepared photocurable 3D printed bioceramic material has a smooth surface.

[0026] Based on the mass fraction of the aluminum dihydrogen phosphate sol, the photosensitive ceramic slurry of this invention includes 0.01 to 0.05 parts of dye, specifically 0.01, 0.02, 0.03, 0.04, or 0.05 parts. In one embodiment of this invention, the dye can be lemon yellow. The use of lemon yellow as a dye in this invention can effectively improve the precision of photopolymer 3D printing, thereby facilitating the preparation of photopolymer 3D printed bioceramic materials with complex structures.

[0027] Based on the mass fraction of the aluminum dihydrogen phosphate sol, the photosensitive ceramic slurry of the present invention comprises 5 to 10 parts of water, specifically 5, 6, 7, 8, 9.31, or 10 parts. As one embodiment of the present invention, the solid content of the photosensitive ceramic slurry can be 20 to 30 wt%.

[0028] As one embodiment of the present invention, the preparation method of the photosensitive ceramic slurry may include the following steps: first mixing aluminum dihydrogen phosphate sol, ceramic powder and a portion of monomers to obtain a first mixture; second mixing the first mixture with a mixed aqueous solution of photoinitiator and the remaining monomers to obtain a second mixture; and third mixing the second mixture, an aqueous solution of stabilizer and an aqueous solution of dye to obtain the photosensitive ceramic slurry.

[0029] In one embodiment of the present invention, the monomers are specifically acrylic acid and acrylamide; the remaining monomers are specifically polyvinyl alcohol diacrylate.

[0030] In one embodiment of the present invention, the first mixing is specifically ball milling mixing, wherein the rotation speed of the ball milling mixing can be 2500~3500 rpm, specifically 3000 rpm; the time can be 2~5 min, specifically 3 min; and the ball milling mixing is specifically carried out in a planetary ball mill.

[0031] In one embodiment of the present invention, the concentration of the photoinitiator in the mixed aqueous solution of the photoinitiator and the remaining monomer can be 8~9 mg / mL, specifically 8.5 mg / mL, and the concentration of the remaining monomer can be 15~20 mg / mL, specifically 17 mg / mL. The present invention does not have any special limitation on the second mixing method, and any method known to those skilled in the art can be used to achieve sufficient mixing of the components.

[0032] In one embodiment of the present invention, the concentration of the stabilizer aqueous solution can be 8~12 mg / mL, specifically 10 mg / mL; the concentration of the dye aqueous solution can be 0.03~0.07 g / mL, specifically 0.05 g / mL; the present invention does not have a special limitation on the third mixing method, as long as a method known to those skilled in the art can be used to achieve sufficient mixing of the components.

[0033] This invention provides a photopolymerizable 3D printing bioceramic material, the raw material of which is the photosensitive ceramic slurry described in the above technical solution.

[0034] In one embodiment of the present invention, the photopolymerizable 3D printed bioceramic material has a porous structure, which may include a first-order porous structure and a second-order porous structure. In another embodiment, the photopolymerizable 3D printed bioceramic material macroscopically possesses a first-order porous structure, preferably arranged in an array, with a pore size of 400-600 μm; the spacing between adjacent pores, with the center of the pore as a reference, can be 800-1000 μm; the first-order porous structure of the present invention can be designed according to actual needs. In yet another embodiment, the support structure of the photopolymerizable 3D printed bioceramic material has a second-order porous structure with a pore size <400 μm; the second-order porous structure of the present invention is spontaneously formed during the preparation of the photopolymerizable 3D printed bioceramic material.

[0035] As one embodiment of the present invention, the photocurable 3D printing bioceramic material includes calcium, phosphorus, aluminum, oxygen, and carbon. In this embodiment of the present invention, the mass content of each element in the photocurable 3D printing bioceramic material is as follows: Ca 15.383%, P 28.698%, Al 12.079%, O 41.279%, and C 2.561%.

[0036] This invention provides a method for preparing the photopolymerizable 3D printed bioceramic material described above, comprising the following steps: The photosensitive ceramic slurry was sequentially subjected to photocuring 3D printing, drying, and sintering to obtain the photocuring 3D printed bioceramic material.

[0037] This invention involves photopolymerizing the photosensitive ceramic slurry into a precursor using 3D printing. In one embodiment, the photopolymerization 3D printing can specifically be Digital Light Processing (DLP) 3D printing. Preferably, 3D design software (including Shapr3D or Solidworks) is used to design a 3D model of the bioceramic material for photopolymerization 3D printing according to actual needs. The 3D model is then converted to STL format and imported into CeraMatrix slicing software to generate slice files. The thickness of the first slice can be 75-125 μm, specifically 100 μm, and the thickness of other layers can be 25-75 μm, specifically 50 μm. The photosensitive ceramic slurry is then poured into the feed tank of the photopolymerization 3D printer, and the slice files are imported into the printer for photopolymerization 3D printing. In one embodiment of the present invention, the dimensions of the three-dimensional model can be designed according to the required photopolymerizable 3D printing bioceramic material. For example, the photopolymerizable 3D printing bioceramic material can be a cuboid bioceramic scaffold or a cylindrical bioceramic scaffold. When the photopolymerizable 3D printing bioceramic material has a primary porous structure, the photopolymerizable 3D printing bioceramic material can specifically be a cuboid porous bioceramic scaffold or a cylindrical porous bioceramic scaffold. In this embodiment of the present invention, when the photopolymerizable 3D printing bioceramic material is a cuboid porous bioceramic scaffold, the bottom surface of its three-dimensional model is a square with a side length of 9 mm and a height of 2.2 mm. The pore diameter of the primary porous structure can be 805.26 μm, and the spacing between adjacent pores can be 1089.47 μm. When the photopolymerizable 3D printing bioceramic material is a cylindrical porous bioceramic scaffold, the diameter of its three-dimensional model can be 5.5 mm, the height can be 1.2 mm, the pore diameter of the primary porous structure can be 500 μm, and the spacing between adjacent pores can be 1000 μm.

[0038] In one embodiment of the present invention, the conditions for photopolymerization 3D printing include: using an ultraviolet light source, wherein the wavelength of the ultraviolet light source can be 405nm; and the initial layer exposure intensity can be 38~42mW / cm². 2 Specifically, it can be 40mW / cm 2 The exposure time can be 10~20s, specifically 15s; the exposure intensity for the remaining layers can be 18~22mW / cm². 2 Specifically, it can be 20mW / cm 2 The exposure time can be 5-10 seconds, specifically 7 seconds; the platform temperature can be maintained at room temperature (25°C). The precursor obtained by photopolymerization 3D printing using the photosensitive ceramic slurry described in this invention is a flexible material that can be freely compressed and restored, cut, and individually filled to fill bone defects.

[0039] After obtaining the precursor, the present invention dries the precursor to obtain a green body. In one embodiment of the present invention, the drying process preferably includes washing, where the washing reagent is water, specifically tap water; the washing method is rinsing. The present invention removes uncured photosensitive ceramic slurry adhering to the surface and internal pores of the precursor through washing. In one embodiment of the present invention, the drying process includes sequentially performing a first drying, a second drying, and a third drying; the temperature of the first drying can be 20~30℃, specifically room temperature, and the time can be 6~8 days, specifically 7 days; the temperature of the second drying can be 50~60℃, specifically 55℃, and the time can be 6~8 days, specifically 7 days; the temperature of the third drying can be 95~105℃, specifically 100℃, and the time can be 6~8 days, specifically 7 days. In the present invention, the first drying serves to fix the shape of the precursor, the second drying serves to remove free water from the material, and the third drying serves to further remove residual free water from the material.

[0040] After obtaining the green body, the present invention sintersects the green body to obtain the photopolymerizable 3D printed bioceramic material. In one embodiment of the present invention, the sintering is carried out in an air atmosphere; the sintering includes sequentially performing a first sintering and a second sintering; the temperature of the first sintering can be 450~550℃, specifically 500℃; the heating rate from room temperature to the first sintering temperature can be 0.8~1.2℃ / min, specifically 1℃ / min; the holding time of the first sintering can be 4~6h, specifically 5h; the temperature of the second sintering can be 1100~1300℃, specifically 1200℃; the heating rate from the first sintering temperature to the second sintering temperature can be 0.8~1.2℃ / min, specifically 1℃ / min; the holding time of the second sintering can be 2~4h, specifically 3h. In the present invention, the function of the first sintering is to remove most of the organic components and residual moisture from the green body; the function of the second sintering is to improve the density of the photopolymerizable 3D printed bioceramic material. In this embodiment of the invention, the green body is placed in a ceramic crucible, and then the ceramic crucible containing the green body is placed in a heating furnace for sintering. As one embodiment of the invention, the sintering process preferably includes natural cooling to room temperature, followed by packaging and sterilization. The sterilization can be high-pressure steam sterilization. The invention does not specifically limit the specific conditions for high-pressure steam sterilization; conditions well known to those skilled in the art can be used.

[0041] As one embodiment of the present invention, compared with the three-dimensional model of the photocurable 3D printed bioceramic material, the shrinkage rate of the photocurable 3D printed bioceramic material during the preparation process can be 8~12%, that is, only about 10%, which is much lower than that of the photosensitive resin 3D printed bioceramic material (the shrinkage rate is usually >20%).

[0042] The photopolymerizable 3D-printed bioceramic material provided by this invention exhibits good cell compatibility and can promote osteogenic differentiation of pre-osteoblasts MC3T3-E1, thus promoting bone regeneration. The photopolymerizable 3D-printed bioceramic material of this invention has a porous structure and can be used as a medical porous bioceramic scaffold.

[0043] This invention provides the application of the photocurable 3D printed bioceramic material described in the above technical solution or the photocurable 3D printed bioceramic material prepared by the preparation method described in the above technical solution in the preparation of materials that promote bone regeneration.

[0044] This invention provides the application of the photocurable 3D printed bioceramic material described in the above technical solution or the photocurable 3D printed bioceramic material prepared by the preparation method described in the above technical solution in the preparation of cranial repair scaffolds.

[0045] Figure 1 This is a flowchart and feature illustration of the fabrication process of the porous bioceramic scaffold in an embodiment of the present invention. Figure 1 As can be seen, the precursor of the photopolymer 3D printing bioceramic material provided by this invention can be freely compressed and restored, trimmed and individually filled in bone defects. If printing defects occur, they can be trimmed at will. Even if the precursor structure is deformed by external force after printing, it can still restore its original shape.

[0046] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0047] Example 1 The preparation of bioceramic materials (specifically porous bioceramic scaffolds) using digital light processing 3D printing technology includes the following steps: S1: Design the support model A three-dimensional model of a porous bioceramic scaffold was designed using Shapr3D 3D design software. The porous bioceramic scaffold is specifically a cuboid porous bioceramic scaffold with a square base, a side length of 9 mm, and a height of 2.2 mm. The pore size of the first-level pore structure can be 805.26 μm, and the spacing between adjacent pores can be 1089.47 μm. The 3D model was converted into STL format and imported into CeraMatrix slicing software to generate slice files. The thickness of the first slice was set to 100 μm, and the thickness of other slices was set to 50 μm.

[0048] S2: Preparation of photosensitive ceramic slurry The 85wt% H3PO4 solution was diluted to 60wt% with deionized water to obtain a diluted H3PO4 solution; 31.84g of Al(OH)3 powder was added to 196g of the diluted H3PO4 solution and the mixture was stirred at 100℃ for 3h to obtain aluminum dihydrogen phosphate sol (AP sol). 13g of hydroxyapatite (particle size 60-80nm), 6.93g of acrylamide, and 0.624g of acrylic acid were added to 30g of the AP sol. The resulting mixture was ball-milled in a planetary ball mill at 3000 rpm for 3 min. 4mL of a mixed aqueous solution of phenyl-2,4,6-trimethylbenzoyl lithium phosphinate (LAP) and polyvinyl alcohol diacrylate (PEGDA750) was added to the ball-milled material. The concentration of LAP in the mixed aqueous solution was 8.5mg / mL, and the concentration of PEGDA750 was 17mg / mL. Then, 1mL of a 10mg / mL aqueous solution of 4-methoxyphenol was added. Finally, 0.2mL of a 0.05g / mL aqueous solution of lemon yellow was added to obtain the photosensitive ceramic slurry.

[0049] S3: Preparation of precursors The photosensitive ceramic slurry is poured into the feed tank of a photopolymer 3D printer, the slice file is imported into the photopolymer 3D printer, and 3D printing is performed to obtain the precursor. The 3D printing conditions include: using a 405nm ultraviolet light source and setting the first layer exposure intensity to 40mW / cm². 2 The exposure time was 15 seconds, and the exposure intensity for the remaining layers was 20 mW / cm². 2 The exposure time was 7 seconds, and the platform temperature was room temperature (25℃). S4: Preparation of green body The precursor is rinsed with tap water to remove uncured photosensitive ceramic slurry adhering to the surface and internal channels, and then dried at room temperature for one week to fix its shape. The dried material is placed in an oven and dried at 55°C for one week, and then dried at 100°C for one week to remove free water, thus obtaining a green body.

[0050] S5: Sintered green body The green body is placed in a ceramic crucible, and the ceramic crucible containing the green body is transferred to a heating furnace. In an air atmosphere, the temperature is increased from room temperature to 500°C at a rate of 1°C / min and held for 5 hours to remove most of the organic components and residual moisture from the green body. Then, the temperature is increased from 500°C to 1200°C at a rate of 1°C / min and held for 3 hours to increase the density. Finally, the temperature is allowed to cool naturally to room temperature to obtain a porous bioceramic scaffold.

[0051] S6: Sterilization treatment The porous bioceramic scaffold was packaged and then sterilized using high-pressure steam sterilization.

[0052] Example 2 The procedure is the same as in Example 1, except that the porous bioceramic scaffold prepared in this example is a cylindrical porous bioceramic scaffold with a diameter of 5.5 mm and a height of 1.2 mm in its three-dimensional model. The pore size of the first-level pore structure can be 500 μm, and the spacing between adjacent pores can be 1000 μm.

[0053] Test Example 1 Figure 2 The images show physical images of the porous bioceramic scaffold obtained after greening and sintering in Example 1, as well as scanning electron microscope images of the porous bioceramic scaffold and its cross-sectional pores. The results show that the porous bioceramic scaffold obtained after sintering has a designed first-order pore structure with a pore size of approximately 400-600 μm and a pore spacing of approximately 800-1000 μm. This first-order pore structure is suitable for bone repair, promotes osteogenic differentiation of stem cells, and facilitates bone tissue angiogenesis. In addition, a second-order pore structure spontaneously forms inside the struts of the porous bioceramic scaffold obtained after sintering, with a pore size of <400 μm. This second-order pore structure facilitates the transport of nutrients and metabolites, and also facilitates the ingrowth of new bone tissue and material degradation.

[0054] Table 1 shows the elemental analysis results of the porous bioceramic scaffold prepared in Example 1. As can be seen from Table 1, the porous bioceramic scaffold contains calcium and phosphorus. With the degradation of the porous bioceramic scaffold and the release of the above elements, it can play a certain role in promoting osteogenic formation.

[0055] Table 1. Elemental analysis results of the porous bioceramic scaffolds prepared in Example 1

[0056] Test Example 2 Table 2 shows the shrinkage rate test results of the porous bioceramic scaffolds prepared in Examples 1 and 2. As can be seen from Table 2, the shrinkage rate of the porous bioceramic scaffolds prepared in this invention is about 10%, which is lower than that of photosensitive resin 3D printed bioceramic materials (the shrinkage rate is usually >20%), making it more suitable for bone defect sites.

[0057] Table 2. Shrinkage rate test results of the porous bioceramic scaffolds prepared in Example 1 and Example 2

[0058] Test Example 3 To facilitate performance testing, the photosensitive ceramic slurry was prepared in this test example according to the method of Example 1, and the photosensitive ceramic slurry was further used to prepare a bioceramic scaffold without the first pore structure. The bioceramic scaffold in this test example is specifically a cylindrical bioceramic scaffold with a diameter of 6 mm and a height of 9 mm (without the first pore structure).

[0059] Figure 3 The images show the nanoindentation test results of the bioceramic scaffold prepared in Test Example 3, specifically the load-indentation depth curve, modulus-indentation depth curve, and hardness-indentation depth curve of the bioceramic scaffold, as well as a comparison of the modulus-hardness of the bioceramic scaffold, cortical bone, cancellous bone, and calcium phosphate bone cement; Figure 3 As can be seen, the hardness and modulus of the bioceramic scaffold prepared using the photosensitive ceramic slurry of the present invention are approximately 3.85 GPa and 56.41 GPa, respectively. Compared with cortical bone, cancellous bone and calcium phosphate bone cement, the bioceramic scaffold prepared using the photosensitive ceramic slurry of the present invention exhibits higher hardness and modulus.

[0060] Test Example 4 The sterilized porous bioceramic scaffold from Example 1 was used in in vitro cell experiments to evaluate its effect on the adhesion of pre-osteoblast MC3T3-E1 cells. The specific steps are as follows: In a clean bench, T25 flask cultured cells with a monolayer fusion rate of 80-90% were digested with trypsin solution at a concentration of 2.5 g / mL. When the cells were observed to become rounder and brighter under a microscope, the trypsin solution was discarded. Then, 1 mL of α-MEM medium (complete medium) containing 10 vol% fetal bovine serum and 1 vol% penicillin and streptomycin was added to stop the digestion. The cells were then mixed by pipetting to obtain a cell suspension.

[0061] The sterilized porous bioceramic scaffolds were transferred to 24-well plates, with one scaffold placed in each well. 100 μL of cell suspension was slowly added dropwise to the porous bioceramic scaffolds. The 24-well plates were then transferred to a cell culture incubator and incubated for 1 hour at 37°C with 95% oxygen and 5% carbon dioxide to ensure cell adhesion to or deposition around the scaffolds. The 24-well plates were then removed and, in a clean bench, 1.5 mL of complete culture medium was added to the wells containing the porous bioceramic scaffolds, ensuring the medium level completely submerged the scaffold surface. Finally, the 24-well plates were returned to the cell culture incubator and cultured for 3 and 7 days, respectively, before harvesting the samples. All handling should be gentle to avoid scratching the cells at the base of the porous bioceramic scaffolds.

[0062] After culture, the porous bioceramic scaffold containing cells was washed with PBS, and then the washed porous bioceramic scaffold was immersed in a 2.5 wt% glutaraldehyde solution and fixed at 4°C for 2 h. Then, the porous bioceramic scaffold was rinsed with PBS solution at 4°C for 1 h, with the medium changed twice in between to remove excess glutaraldehyde solution. Subsequently, it was dehydrated with a gradient of alcohol (50 vol%, 70 vol%, 80 vol%, 90 vol%, 100 vol%) for 15 min each time. Finally, the porous bioceramic scaffold was sputter-coated with gold and the surface cells of the porous bioceramic scaffold were imaged using a scanning electron microscope.

[0063] Figure 4 The SEM images show cell adhesion on the surface of the porous bioceramic scaffold after 3 and 7 days of culture in Test Example 4. It can be seen that after 3 and 7 days of co-culture with the porous bioceramic scaffold, the cells were able to adhere to the surface of the porous bioceramic scaffold, indicating that the porous bioceramic scaffold has good cell compatibility.

[0064] Test Example 5 (1) Place the sterilized porous bioceramic scaffold from Example 1 into a 50mL centrifuge tube in a clean bench, add complete culture medium to make the concentration of the porous bioceramic scaffold reach 0.12g / mL (where the mass of each porous bioceramic scaffold is 0.1g), and then transfer the centrifuge tube to a cell culture incubator for 3 days; transfer the material extract obtained after the culture to a new 50mL centrifuge tube. The material extract does not require any additional treatment and is ready for use.

[0065] (2) Material group: When the cell monolayer fusion of T25 flask reaches 80-90%, the cells are seeded into 6-well plates and 3.5cm dishes respectively, then 1.5mL of complete culture medium is added, shaken evenly and placed in a cell culture incubator for 1 day to ensure uniform cell adhesion; then the culture medium is discarded, 2.5mL of the material extract is added, and placed in a cell culture incubator for culture, and the material extract is replaced every 3 days; alkaline phosphatase cell staining is collected on days 7 and 14, and alizarin red blood cell staining is collected on days 21 and 28.

[0066] (3) Control group: Refer to step (2) for operation, the only difference is the culture medium used for cell culture. The control group uses complete culture medium to culture cells (i.e., does not use porous bioceramic scaffold), while the material group in step (2) uses material extract to culture cells.

[0067] Figure 5 The figures show the experimental results and statistical results of alkaline phosphatase (ALP) staining and Alizarin Red S (ARS) staining in the material group and control group of Example 5. Figure a shows the results of the alkaline phosphatase cell staining experiment, figure b shows the statistical results, figure c shows the results of the Alizarin Red S staining experiment, and figure d shows the statistical results. Figure 5 As can be seen, after 7 and 14 days of indirect co-culture between the porous bioceramic scaffold and cells, ALP staining showed that the alkaline phosphatase staining in the material group was deeper than that in the control group; after 21 and 28 days of indirect co-culture between the porous bioceramic scaffold and cells, ARS staining showed that the calcium nodule staining in the material group was deeper than that in the control group. Statistical results further showed that in both ALP and ARS staining experiments, the levels of alkaline phosphatase and calcium nodules in the cells of the material group were significantly higher than those in the control group. Alkaline phosphatase and calcium nodules are both markers related to osteogenic differentiation, and the above results indicate that the porous bioceramic scaffold described in this invention promotes osteogenic differentiation of pre-osteoblasts MC3T3-E1.

[0068] Test Example 6 The porous bioceramic scaffold, sterilized in Example 2, was used in a skull defect repair experiment to evaluate its impact on skull defect repair. The specific steps are as follows: (1) Materials group: 12 SD rats were used to drill holes to create 5mm skull defects. Porous bioceramic scaffolds were implanted into the defect sites. Samples were taken at 8 and 12 weeks, with 6 rats at each time point. Samples missing due to postoperative infection or implant displacement were excluded to ensure that the number of effective samples at each time point was ≥3.

[0069] (2) Control group: Follow the procedure in step (1), except that no porous bioceramic scaffold was implanted in the control group.

[0070] Figure 6Morphological observation images and micro-CT scan images of the healing of skull defects in SD rats in the material group and control group of Test Example 6 are shown. Figure 6 As can be seen, after 8 and 12 weeks of healing, the skull defects in both the control group and the material group were not completely repaired. However, the new bone tissue in the material group was able to grow along the surface of the porous bioceramic scaffold.

[0071] Figure 7 The images show H&E and Masson staining of tissue sections from SD rats in the material group and control group for skull defect repair in Test Example 6; where Ft represents fibrous tissue and NB represents newly formed bone tissue. Figure 7 As can be seen, the newly formed tissue in the control group was fibrous tissue; while in the material group, in addition to the fibrous tissue growing along the surface and internal pores of the porous bioceramic scaffold, new bone tissue appeared at the implantation site.

[0072] The above animal experimental results demonstrate that the porous bioceramic scaffold of the present invention has a significant effect on promoting the repair of skull defects.

[0073] Test Example 7 Experimental group: Photosensitive ceramic slurry was prepared according to the method of Example 1, and a bioceramic scaffold without the first pore structure was further prepared using the photosensitive ceramic slurry. The bioceramic scaffold was specifically a cylindrical bioceramic scaffold with a diameter of 18 mm and a height of 3.5 mm (without the first pore structure).

[0074] Control group: The procedure was the same as the experimental group, except that aluminum dihydrogen phosphate sol (AP sol) was omitted. Instead, a photosensitive ceramic slurry was prepared directly using a mixed aqueous solution of hydroxyapatite, acrylic acid, acrylamide, lithium phenyl-2,4,6-trimethylbenzoylphosphinate and polyvinyl alcohol diacrylate, an aqueous solution of 4-methoxyphenol and an aqueous solution of lemon yellow. The bioceramic scaffold was then prepared by 3D printing, drying and sintering.

[0075] Figure 8 The images show the newly prepared photosensitive ceramic slurry (0 min) and the control group in Test Example 7, as well as the images after 30 min. The results show that, compared with the photosensitive ceramic slurry with added AP sol, the photosensitive ceramic slurry without added AP sol exhibits obvious sedimentation and stratification after 30 min, which is not conducive to 3D printing.

[0076] Figure 9 The images show the bioceramic scaffolds prepared in the experimental and control groups in Test Example 7. The results show that the photosensitive ceramic slurry without AP sol is prone to cracking during sintering after 3D printing and drying.

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photosensitive ceramic paste, comprising the following components by mass parts: 50-55 parts aluminum dihydrogen phosphate sol, 20-25 parts ceramic powder, 10-15 parts monomer, 0.05-0.10 parts photoinitiator, 0.01-0.05 parts stabilizer, 0.01-0.05 parts dye, and 5-10 parts water.

2. The photosensitive ceramic slurry according to claim 1, characterized in that, The preparation method of the aluminum dihydrogen phosphate sol includes the following steps: mixing phosphoric acid with Al(OH)3 powder to carry out a neutralization reaction to obtain the aluminum dihydrogen phosphate sol; the concentration of the phosphoric acid is 55~65wt%; the mass ratio of the phosphoric acid to the Al(OH)3 powder is 196:30~35; the reaction temperature is 95~105℃ and the time is 2~4h.

3. The photosensitive ceramic slurry according to claim 1 or 2, characterized in that, The ceramic powder includes one or more of hydroxyapatite, β-tricalcium phosphate, and calcium silicate; the particle size of the ceramic powder is 60~80 nm.

4. The photosensitive ceramic slurry according to claim 1 or 2, characterized in that, The monomers include acrylic acid, acrylamide, and polyvinyl alcohol diacrylate; the mass ratio of acrylic acid, acrylamide, and polyvinyl alcohol diacrylate is 12~13:138~139:1~2.

5. The photosensitive ceramic slurry according to claim 1 or 2, characterized in that, The photoinitiator is lithium phenyl-2,4,6-trimethylbenzoylphosphinic acid; the stabilizer is an acrylic acid polymerization inhibitor; and the dye is lemon yellow.

6. A photopolymerizable 3D printing bioceramic material, wherein the raw material is the photosensitive ceramic slurry described in any one of claims 1 to 5.

7. The method for preparing the photopolymerizable 3D printed bioceramic material according to claim 6, comprising the following steps: The photosensitive ceramic slurry was sequentially subjected to photocuring 3D printing, drying, and sintering to obtain the photocuring 3D printed bioceramic material.

8. The preparation method according to claim 7, characterized in that, The conditions for photopolymerization 3D printing include: using an ultraviolet light source; and an initial exposure intensity of 38~42mW / cm². 2 The exposure time is 10-20 seconds; the exposure intensity for the remaining layers is 18-22 mW / cm². 2 The exposure time is 5-10 seconds; The drying process includes sequentially performing a first drying, a second drying, and a third drying; the temperature of the first drying is 20~30℃, and the time is 6~8 days; the temperature of the second drying is 50~60℃, and the time is 6~8 days; the temperature of the third drying is 95~105℃, and the time is 6~8 days. The sintering process includes a first sintering and a second sintering in sequence; the temperature of the first sintering is 450~550℃ and the holding time is 4~6h; the temperature of the second sintering is 1100~1300℃ and the holding time is 2~4h.

9. The application of the photocurable 3D printed bioceramic material of claim 6 or the photocurable 3D printed bioceramic material prepared by the preparation method of claim 7 or 8 in the preparation of materials that promote bone regeneration.

10. The application of the photocurable 3D printed bioceramic material of claim 6 or the photocurable 3D printed bioceramic material prepared by the preparation method of claim 7 or 8 in the preparation of cranial repair scaffolds.

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