A 3D printed piezoelectric bone repair scaffold based on shape memory polymer and its preparation method

Abstract

The present invention discloses a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer and a preparation method thereof, comprising the following steps: adding barium titanate to a dopamine hydrochloride solution, stirring, and then adding a silane coupling agent; after the reaction is complete, adding the barium titanate to a silver ammonia solution to prepare modified barium titanate nanoparticles; adding the modified barium titanate nanoparticles to epoxy soybean oil acrylate, adding a diluent and a photoinitiator to obtain a photocurable slurry; and using the obtained photocurable slurry through a photocurable 3D printer to prepare a bone repair scaffold having piezoelectric effect and shape memory function. The present invention can stimulate the piezoelectric material through ultrasonic stimulation or the autogenous movement of the implant site, thereby generating microcurrent to promote bone regeneration; at the same time, due to the advantages of the shape memory material such as small size and variable shape, it can achieve more miniaturized implantation and reduce surgical trauma.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and specifically relates to a 3D-printed piezoelectric bone repair scaffold based on shape memory polymer, and a preparation method and application thereof. Background Art

[0002] Piezoelectric materials have unique physical properties that allow them to generate tiny electric currents when subjected to external mechanical stimulation. Many biomaterials, such as bone, exhibit piezoelectric properties, and mechanical stress can cause tiny changes in their electric fields and currents. This electrical signal generated by physiological mechanical stimulation can serve as an important physiological regulatory signal, affecting cell surface receptors, intracellular pathways, and gene expression. Therefore, by applying external mechanical loads to stimulate the inherent piezoelectric effect of piezoelectric materials and bone tissue, physiologically compatible microcurrents can be generated. This microcurrent can enhance bone cell activity and promote bone repair and regeneration. Among them, barium titanate (BT) has a high piezoelectric coefficient and good biocompatibility, which is conducive to generating sufficient physiological stimulation to promote cell activity without causing immune or toxic reactions, making it suitable as an implant material.

[0003] Shape memory polymers (SMPs) can maintain a temporary shape at low temperatures and return to their preset shape at body temperature or in response to external stimuli. This allows for smaller implants, avoiding excessive wounds. The process also generates stress, keeping the scaffold in close contact with the bone surface, effectively improving fixation strength and long-term stability. Epoxidized soybean oil acrylate (AESO), derived from soybean oil, exhibits excellent biocompatibility and processability, making it an ideal material for bone repair.

[0004] Combining piezoelectric materials and SMPs not only enables the materials to promote bone repair by regulating the current microenvironment and bone integration, but also improves the problem that piezoelectric ceramic materials are difficult to process and customize. Although the advantages of piezoelectric materials and SMPs in the field of bone repair have been discovered, there are few studies that combine these two materials for bone repair. The main reason is that there is a significant difference in the dielectric constant between piezoelectric materials and SMPs. This difference makes it difficult for the material to be polarized, and thus it cannot exhibit macroscopic piezoelectricity. Therefore, how to develop a bone repair scaffold with customizable shape, piezoelectric effect and shape memory function based on SMP is of great significance in the development of biomedicine. Summary of the Invention

[0005] In response to the problems and shortcomings of the existing technology, one of the objectives of the present invention is to develop a bone repair scaffold based on SMP with customizable shape, piezoelectric effect and shape memory function, which can restore its original shape at body temperature or infrared stimulation and fit tightly with bone tissue; at the same time, it can generate microcurrent under the autologous movement of the implantation site or the application of ultrasonic stimulation, and promote bone regeneration by regulating the current microenvironment in the body; and the scaffold can be used to quickly prepare highly customized, porous bone repair scaffolds using a light-curing 3D printer, which is suitable for promotion and application.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned 3D-printed piezoelectric bone repair scaffold based on shape memory polymer.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer, comprising the following steps:

[0009] 1) adding barium titanate to a deionized aqueous solution of dopamine hydrochloride and stirring at room temperature to obtain barium titanate nanoparticles coated with polydopamine;

[0010] 2) Add the silane coupling agent to the suspension in step 1), increase the temperature and continue stirring;

[0011] 3) centrifuging the suspension obtained in step 2), washing and drying the precipitate to obtain barium titanate nanoparticles coated with polydopamine and silane coupling agent;

[0012] 4) adding the barium titanate nanoparticles coated with polydopamine and grafted with silane obtained in step 3) to a silver ammonia solution, stirring in the dark, centrifuging the suspension, washing and drying the precipitate to obtain barium titanate nanoparticles coated with polydopamine and a silane coupling agent;

[0013] 5) adding the silver nanoparticles deposited in step 4) and the barium titanate nanoparticles coated with polydopamine and a silane coupling agent to epoxy soybean oil acrylate, adding a diluent and a photoinitiator, stirring, and then homogenizing by ultrasonication to obtain a UV-curable slurry;

[0014] 6) The UV-curable slurry obtained in step 5) is added to a light-curing 3D printer, and after printing using the light-curing 3D printer, it is washed with anhydrous ethanol and dried to obtain a bone repair scaffold with piezoelectric effect and shape memory function.

[0015] Preferably, in step 1), the mass / volume ratio of the barium titanate to deionized water is (60-120) g / L, and the mass / volume ratio of the dopamine hydrochloride to deionized water is (1-2) g / L.

[0016] Preferably, in step 1), the solution pH is controlled at 8 to 9, and the stirring time is 20 to 30 hours. Furthermore, the solution pH is controlled at 8.5, as the pH required for dopamine polymerization is approximately 8.5, and at this pH, dopamine is better able to polymerize to form polydopamine.

[0017] Preferably, in step 2), the silane coupling agent is selected from γ-methacryloxypropyltrimethoxysilane, and its added concentration is 3 to 5 ml / L. γ-methacryloxypropyltrimethoxysilane has a silylmethoxy group at one end, which can graft onto polydopamine; and a methacryloxy group at the other end, which can polymerize with the photocurable resin under ultraviolet light to form a covalent bond.

[0018] Preferably, in step 2), after adding the silane coupling agent, the reaction temperature is 50 to 70 ° C, and the reaction time is 4 to 8 hours.

[0019] Preferably, in step 3), the concentration of the silver ammonia solution added is 0.01 to 0.04 mol / L, and the mass / volume ratio of the barium titanate nanoparticles encapsulating polydopamine and grafted with silane to the silver ammonia solution is (15 to 20) g / L.

[0020] Preferably, in step 4), the mass ratio of the barium titanate nanoparticles deposited with silver nanoparticles and coated with polydopamine and silane coupling agent to the epoxy soybean oil acrylate is 5 to 20%.

[0021] Preferably, in step 4), the mass ratio of the diluent to the epoxy soybean oil acrylate is 5 to 20%, and the mass ratio of the photoinitiator to the epoxy soybean oil acrylate is 0.5 to 2%.

[0022] Preferably, in step 4), the reaction time is 2 to 8 hours.

[0023] Preferably, the diluent is selected from polyethylene glycol diacrylate, and the photoinitiator is selected from phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0024] On the other hand, the present invention provides a 3D-printed piezoelectric bone repair scaffold based on shape memory polymer, and the bone repair scaffold is prepared by the preparation method in the above scheme.

[0025] The above-mentioned piezoelectric bone repair scaffold based on shape memory polymer can be quickly prepared using a light-curing 3D printer and can be highly customized according to the irregular shape of the bone defect site; the piezoelectricity of the bone repair scaffold matches the bone tissue and can regulate the current microenvironment of the bone defect tissue, promote cell proliferation and differentiation, and thus promote bone regeneration; in addition, the bone repair scaffold also has good shape memory function and can quickly recover to its original shape under near-infrared light, reducing additional damage during implantation, and stress will be generated during the shape recovery process to make the scaffold close to the bone surface, effectively improving the fixation strength and long-term stability.

[0026] The present invention can stimulate piezoelectric materials through ultrasonic stimulation or autonomic movement of the implant site, thereby generating microcurrents to promote bone regeneration; at the same time, due to the advantages of shape memory materials such as small size and variable shape, more miniaturized implants can be achieved, reducing surgical trauma.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) This invention proposes for the first time to combine shape memory polymers with piezoelectric materials, which not only improves the processing and molding problems of piezoelectric materials, but also combines the advantages of both, and can promote bone repair at the bone defect site through an improved current microenvironment and close bone adhesion.

[0029] 2) The bone repair scaffold of the present invention has mechanical properties and shape memory functions close to those of bone tissue, which can meet the needs of bone repair. In addition, the scaffold can be irradiated with near-infrared light both in vitro and in vivo to enable the scaffold to quickly restore its shape.

[0030] 3) The present invention uses a modified method of loading a conductive phase and covalently functionalizing barium titanate nanoparticles, so that when added to a matrix material with a large difference in dielectric constant, the entire stent can be effectively polarized, exhibiting macroscopic piezoelectricity.

[0031] 4) The bone repair scaffold of the present invention has good biocompatibility and can provide a continuous electrical microenvironment after implantation. The stable surface potential promotes rapid and extensive healing of bone defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a picture of the microscopic surface structure of a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2, obtained by scanning electron microscopy;

[0033] Figure 2 This is a bar graph of the compressive strength, compression modulus, and maximum compression deformation of a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2;

[0034] Figure 3This is a diagram of the shape memory recovery process of a sample of a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2, recorded by a digital camera under infrared drive;

[0035] Figure 4 The d33 quasi-static piezoelectric constant histogram of the bone repair scaffolds obtained in Examples 1 to 3;

[0036] Figure 5 This is a graph showing an in vitro current output test of a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2;

[0037] Figure 6 This is a graph showing the proliferation ability of MC3T3-E1 cells tested using a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2;

[0038] Figure 7 This is a test diagram of the differentiation-promoting effect of a bone repair scaffold with piezoelectric effect and shape memory function on rat bone mesenchymal stem cells (rBMSC) obtained in Example 2;

[0039] Figure 8 This is a bar graph showing the effect of a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2 on promoting bone regeneration in a rat skull defect model. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, these examples are not to be construed as limiting the present invention and are merely examples.

[0041] Unless otherwise specified, the experimental methods or test methods described in the following examples are all conventional methods; the reagents and materials described are all obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0042] Example 1

[0043] A method for preparing a 3D-printed piezoelectric bone repair scaffold based on shape memory polymer comprises the following steps:

[0044] 1) Add 60 g of barium titanate to a deionized aqueous solution of dopamine hydrochloride (concentration: 2 g / L) and stir at room temperature for 24 hours to obtain barium titanate nanoparticles coated with polydopamine;

[0045] 2) Add 3.6 g of silane coupling agent (γ-methacryloxypropyltrimethoxysilane) to the suspension from step 1), heat to 60 °C and continue stirring for 6 hours;

[0046] 3) centrifuging the suspension obtained in step 2), washing and drying the precipitate to obtain barium titanate nanoparticles coated with polydopamine and silane coupling agent;

[0047] 4) 17.5 g of the polydopamine-coated and silane-grafted barium titanate nanoparticles obtained in step 3) was added to 1 L of a 0.02 mol / L silver ammonia solution. The suspension was stirred in the dark and centrifuged. The precipitate was washed and dried to obtain barium titanate nanoparticles coated with polydopamine and a silane coupling agent and deposited silver nanoparticles.

[0048] 5) The barium titanate nanoparticles deposited with silver nanoparticles obtained in step 4) and coated with polydopamine and a silane coupling agent were added to epoxy soybean oil acrylate (added in an amount of 5 wt%), polyethylene glycol diacrylate (added in an amount of 10 wt%) as a diluent, and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (added in an amount of 1 wt%) as a photoinitiator. After stirring, a UV-curable slurry was obtained by ultrasonic homogenization.

[0049] 6) The UV-curable slurry obtained in step 5) is added to a light-curing 3D printer, and after printing using the light-curing 3D printer, it is washed with anhydrous ethanol and dried to obtain a bone repair scaffold with piezoelectric effect and shape memory function.

[0050] Example 2

[0051] A preparation method for a 3D-printed bone repair scaffold based on a shape memory polymer is substantially the same as that in Example 1, except that the specific steps of step 5) include: adding the barium titanate nanoparticles deposited with silver nanoparticles obtained in step 4) and coated with polydopamine and a silane coupling agent to epoxy soybean oil acrylate (added in an amount of 10 wt%), adding polyethylene glycol diacrylate (added in an amount of 10 wt%) as a diluent, and adding phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (added in an amount of 1 wt%) as a photoinitiator, stirring, and then ultrasonically homogenizing to obtain a UV-curable slurry.

[0052] Example 3

[0053] A 3D-printed bone repair scaffold based on a shape memory polymer, the preparation method of which is substantially the same as that of Example 1, except that the specific steps of step 5) include: adding the barium titanate nanoparticles deposited with silver nanoparticles obtained in step 4) and coated with polydopamine and a silane coupling agent to epoxy soybean oil acrylate (added in an amount of 20 wt%), adding polyethylene glycol diacrylate (added in an amount of 10 wt%) as a diluent, adding phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (added in an amount of 1 wt%) as a photoinitiator, stirring, and then ultrasonically homogenizing to obtain a UV-curable slurry.

[0054] Comparative Example

[0055] 1) Polyethylene glycol diacrylate (10 wt%) as a diluent and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (1 wt%) as a photoinitiator were added to epoxy soybean oil acrylate. The mixture was stirred and homogenized by ultrasonication to obtain a UV-curable slurry.

[0056] 2) adding the UV-curable slurry obtained in step 1) into a light-curing 3D printer, printing with the light-curing 3D printer, and then washing and drying with anhydrous ethanol to obtain a bone repair scaffold with shape memory function.

[0057] Application Examples

[0058] The present invention takes the product of Example 2 as an example to illustrate the structure and material properties of a bone repair scaffold with piezoelectric effect and shape memory function:

[0059] Figure 1 This image shows the microscopic surface structure of a bone repair scaffold with piezoelectric effect and shape memory functions, obtained in Example 2, obtained using a scanning electron microscope. The resulting bone repair scaffold exhibits no significant defects and exhibits a highly porous structure. The bone repair scaffold was prepared using a stereolithography 3D printer. The model was drawn using 3D modeling software. The high-porosity model used is characterized by the high precision of stereolithography printing, which preserves the model's highly porous structure.

[0060] Figure 2 This is a bar graph showing the compressive strength, compression modulus, and maximum compressive deformation of a bone repair scaffold with piezoelectric effect and shape memory functions obtained in Example 2. It can be seen that the resulting bone repair scaffold has excellent mechanical properties. The epoxy soybean oil acrylate used exhibits high strength, good toughness, and a maximum deformation greater than 20% after curing. The addition of nanoparticles, which occupies covalent bonds, reduces the strength somewhat, but remains within the mechanical strength range of cancellous bone.

[0061] Figure 3This is a bone repair scaffold with piezoelectric effect and shape memory function obtained in Example 2. The shape memory recovery process of the sample under infrared drive was recorded by a digital camera. It can be seen that after the load is removed at 0 ° C, the sample can maintain the temporary shape unchanged. At 45 ° C or under near-infrared light stimulation, the sample can quickly recover its original shape. Epoxidized soybean oil acrylate is a shape memory polymer that can undergo a reversible transition between a glassy state and a rubbery state. Its glass transition point temperature (Tg) is between 0-45 ° C. Shape memory polymers can fix their shape above Tg, and then when the temperature drops below Tg, they can still retain the temporary shape when the load is removed, and recover their original shape when the temperature rises above Tg. 45 ° C is set here because it has a good recovery speed at this temperature, which facilitates rapid fitting.

[0062] Figure 4 The d33 quasi-static piezoelectric constant bar graph of the bone repair scaffold obtained in Examples 1 to 3 is measured by a quasi-static piezoelectric constant tester. Figure 4 As can be seen from the figure, the d33 piezoelectric constant increases with the addition of silver nanoparticles, coated with polydopamine and a silane coupling agent, resulting in piezoelectric properties similar to those of bone tissue in Examples 2 (~0.9 pC / N) and 3 (~1.4 pC / N). Based on the microcapacitor model, each pair of adjacent Ag nanoparticles can locally act as two electrodes between the BT nanoparticles and the polymer matrix, increasing the dielectric constant of the matrix material and making it more susceptible to polarization. Furthermore, the piezoelectric output is highly dependent on the interface between the polymer matrix and the piezoelectric phase. Silane coupling agents can form direct covalent bonds between the nanoparticles and the polymer chains, facilitating the transfer of mechanical stress from the deforming polymer matrix to the piezoelectric nanoparticles. Taking these two points into account, increasing the nanoparticle addition increases both the microcapacitor content and the covalent bond content of the material, leading to improvements in the d33 piezoelectric constant and current output performance (the first factor primarily affects the piezoelectric constant, while the second factor primarily affects the current output performance).

[0063] Figure 5 This is a graph showing the in vitro current output of a bone repair scaffold with piezoelectric effect and shape memory functions, obtained in Example 2. Copper electrodes were attached to both sides of the scaffold and connected to a nanoammeter. Covered with insulating tape, a 2 Hz external load was applied, and the current output was measured using the nanoammeter. The resulting bone repair scaffold exhibited excellent current output performance (maximum current 146.4 nA).

[0064] The 3D printed piezoelectric bone repair scaffold based on shape memory polymer obtained in Example 2 was applied to the proliferation ability test of MC3T3-E1 cells, specifically including:

[0065] After incubating the MC3T3-E1 cell-scaffold complex for 1, 3, and 5 days, the cell-scaffold complex was washed three times with PBS for 5 minutes each time to remove non-attached cells and cell debris. A mixed culture medium containing 100 μL of α-MEM medium and 10 μL of Cell Counting Kit-8 (CCK-8) reagent was added to each well. For the ultrasonic treatment group, the sample was stimulated with low-intensity pulsed ultrasound (0.7 W / cm2, 1 MHz) for 30 seconds three times a day. The 96-well plate was placed at 37 °C and incubated for 2 hours to allow the enzyme in the cells to completely react and produce color. The culture medium was transferred to a 96-well plate, and the absorbance value of each well was read at 450 nm using a microplate reader to calculate the cell viability and proliferation, as shown in Figure 2. Figure 6 Cell viability and proliferation can be reflected by calculating the difference in absorbance values ​​at different time points. Generally, the absorbance value is proportional to the cell number, so the difference in absorbance value can be used to indirectly reflect the increase in cell number. The results show that the bone repair scaffold with piezoelectric effect and shape memory function can promote the proliferation of MC3T3-E1 cells.

[0066] The 3D-printed piezoelectric bone repair scaffold based on shape memory polymer obtained in Example 2 was applied to a differentiation-promoting test of rat bone mesenchymal stem cells (rBMSCs), specifically including:

[0067] The scaffold was 3D printed into a cylindrical shape with a diameter of 12 mm and a thickness of 1 mm, and placed in a 24-well culture plate after high-pressure sterilization, and 2×104 rBMSCs were added to each well. After 24 hours of co-culture, α-MEM was replaced with osteogenic induction medium, and culture was continued, and the medium was replaced every two days. For the ultrasonic treatment group, the sample was stimulated with low-intensity pulsed ultrasound (0.7 W / cm2, 1 MHz) for 30 seconds three times a day. After culturing rat bone marrow stromal cells (rBMSC) for 7 days, the cell-scaffold complex was removed from the culture medium and washed three times with PBS. Next, 4% paraformaldehyde was added to the fixative, and the cell-scaffold complex was immersed in the fixative for 15 minutes. Finally, the value of alkaline phosphatase activity was measured by the corresponding ALP detection kit, as shown in Figure 7 As shown, it is shown that the bone repair scaffold of the present invention can promote osteoblast differentiation.

[0068] The ability of the shape memory polymer-based 3D printed piezoelectric bone repair scaffold obtained in Example 2 to promote bone regeneration was tested using a rat skull defect model, specifically including:

[0069] Twenty-four female and 24 male Sprague-Dawley rats (4 weeks old, 200-220 g) were randomly divided into four groups. Rats were anesthetized intraperitoneally with sodium phenobarbital (100 mg / kg). A circular defect (d = 5 mm) was created unilaterally in the sagittal suture of the skull using a round drill. The burr hole was continuously irrigated with saline to remove blood and bone debris, and the burr hole was cooled to prevent excessive heat damage to the rats. The treatments for each group were as follows: 1) left empty (control); 2) filled with an AESO scaffold; 3) filled with a non-polarized AESO-10ATP scaffold; and 4) filled with a polarized AESO-10ATP scaffold. The scaffolds had a diameter of 5 mm and a thickness of 1 mm. Four and eight weeks after implantation, the calvarial defects with surrounding normal bone were imaged using micro-CT. The samples were then stored in 4% neutral buffered formalin for 2 days. The skull defect with the scaffold was decalcified in 10% EDTA / HCl for 30 days, dehydrated through graded ethanol, and embedded in paraffin. The area covered by the regenerated bone tissue was measured by ImageJ software 8 weeks after implantation. Figure 8 As shown, the results show that the bone repair scaffold obtained by the present invention can effectively promote the regeneration of bone tissue.

[0070] It should be noted that the embodiments described above are only preferred embodiments of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in any other specific form without departing from the spirit or basic features of the present invention. Therefore, this embodiment is merely an exemplary case and is non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and is intended to encompass all changes within the meaning and scope of the equivalent elements of the claims. Any reference numerals in the claims should not be construed as limiting the claims to which they relate.

Claims

1. A method for preparing a 3D printed piezoelectric bone repair scaffold based on shape memory polymer, characterized in that: The steps include: 1) adding barium titanate to a deionized aqueous solution of dopamine hydrochloride and stirring at room temperature to obtain barium titanate nanoparticles coated with polydopamine; 2) adding a silane coupling agent to the suspension of step 1), heating and continuing stirring; 3) centrifuging the suspension obtained in step 2), washing and drying the precipitate to obtain barium titanate nanoparticles encapsulating polydopamine and a silane coupling agent; 4) adding the barium titanate nanoparticles coated with polydopamine and grafted with silane obtained in step 3) to a silver ammonia solution, stirring in the dark, centrifuging the suspension, washing and drying the precipitate to obtain barium titanate nanoparticles coated with polydopamine and a silane coupling agent; 5) adding the deposited silver nanoparticles obtained in step 4) and the barium titanate nanoparticles coated with polydopamine and a silane coupling agent to epoxy soybean oil acrylate, adding a diluent and a photoinitiator, stirring, and then homogenizing by ultrasonication to obtain a UV-curable slurry; 6) adding the UV-curable slurry obtained in step 5) to a light-curing 3D printer, printing with the light-curing 3D printer, and then washing and drying with anhydrous ethanol to obtain a bone repair scaffold with piezoelectric effect and shape memory function; In step 2), the silane coupling agent is selected from γ-methacryloxypropyltrimethoxysilane. In step 3), the mass / volume ratio of the barium titanate nanoparticles wrapped with polydopamine and grafted with silane to the silver ammonia solution is (15-20) g / L; in step 4), the mass ratio of the barium titanate nanoparticles deposited with silver nanoparticles and wrapped with polydopamine and the silane coupling agent to epoxy soybean oil acrylate is 5-20%.

2. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: In step 1), the mass / volume ratio of the barium titanate to deionized water is (60-120) g / L, and the mass / volume ratio of the dopamine hydrochloride to deionized water is (1-2) g / L.

3. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: In step 1), the pH of the solution is controlled at 8 to 9, and the stirring time is 20 to 30 hours.

4. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: In step 2), the silane coupling agent is added at a concentration of 3 to 5 ml / L.

5. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: In step 2), after adding the silane coupling agent, the reaction temperature is 50 to 70° C. and the reaction time is 4 to 8 hours.

6. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: In step 3), the concentration of the silver ammonia solution added is 0.01 to 0.04 mol / L.

7. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: In step 4), the mass ratio of the diluent to the epoxy soybean oil acrylate is 5-20%, and the mass ratio of the photoinitiator to the epoxy soybean oil acrylate is 0.5-2%.

8. The method for preparing a 3D-printed piezoelectric bone repair scaffold based on a shape memory polymer according to claim 1, characterized in that: The diluent is selected from polyethylene glycol diacrylate, and the photoinitiator is selected from phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide.

9. A 3D printed piezoelectric bone repair scaffold based on shape memory polymer, characterized by: The bone repair scaffold is prepared by the preparation method according to any one of claims 1 to 8.

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