Porous zinc-based composite doped with magnesium oxide and method for preparing same

Abstract

The application discloses a porous zinc-based composite material doped with magnesium oxide and a preparation method thereof. The preparation method comprises the following steps: uniformly mixing a pore-forming agent and nano-MgO to obtain a composite template material; placing the composite template material in a mold, pre-pressing the composite template material under the condition of inert gas and 0.04-0.05 MPa for 30-40 s, preheating the composite template material at 395-400 DEG C for 37-40 min to obtain a preheated template material; pouring an alloy liquid at 560-570 DEG C into the preheated template material so that the liquid surface of the alloy liquid is higher than that of the preheated template material, pressurizing the alloy liquid under the condition of inert gas and 0.15-0.3 MPa for 1-1.5 min, cooling to room temperature, demolding, and obtaining a blank, wherein the part of the blank containing the pore-forming agent is a porous zinc-based composite material blank; and the porous zinc-based composite material blank after the removal of the pore-forming agent is the porous zinc-based composite material doped with magnesium oxide.

Description

Technical Field

[0001] This invention belongs to the field of zinc alloy manufacturing technology, specifically relating to a porous zinc-based composite material doped with magnesium oxide and its preparation method. Background Technology

[0002] Trauma, tumors, infections, and congenital malformations can all cause bone defects, severely affecting limb function. Current mainstream clinical bone defect repair methods all have significant shortcomings: autologous bone transplantation has limited donors and can cause secondary trauma; allogeneic bone transplantation carries the risks of immune rejection and disease transmission; traditional metal implants are prone to stress shielding and bone atrophy, requiring secondary surgery for removal, and the release of metal ions can easily induce long-term inflammation, failing to meet clinical repair needs.

[0003] Biodegradable metal scaffolds have become a key research focus in the field of bone repair due to their excellent biocompatibility, adaptable mechanical properties to bone, and in vivo degradability. Compared to magnesium-based alloys, zinc-based alloys have advantages such as mild corrosion behavior, no risk of hydrogen evolution, and high biocompatibility. The bone healing cycle is adapted to the degradation process of biodegradable metal scaffolds, which can effectively overcome the problems of tissue alkalization and local necrosis caused by the rapid degradation (rapid corrosion) of magnesium-based alloys, showing good prospects for clinical application.

[0004] However, low-alloy Zn-Li-Ca porous scaffolds have inherent drawbacks: the porous structure significantly weakens their mechanical strength, leading to scaffold deformation and fracture, and insufficient support; the zinc matrix has a low corrosion rate, with bone healing preceding scaffold degradation, and scaffold residues easily causing local inflammation; furthermore, low-alloy Zn-Li-Ca porous scaffolds themselves have weak osteogenic and angiogenic capabilities, resulting in unsatisfactory osseointegration. Existing modification techniques struggle to simultaneously achieve synergistic optimization of mechanical properties, corrosion behavior, and biological properties.

[0005] Nano-MgO particles possess excellent biocompatibility and high surface activity, making them an ideal modifying and reinforcing phase for zinc-based scaffolds. However, direct incorporation into the alloy matrix can easily lead to agglomeration and uneven dispersion, resulting in large fluctuations in scaffold performance and unstable modification effects. Existing technologies often employ alloying strategies to improve mechanical properties, but these struggle to simultaneously achieve the desired synergistic optimization of mechanical properties, corrosion rate, and biocompatibility. Currently, there are few systematic studies and mature solutions for achieving this synergistic optimization of performance through pore-forming agent-loaded nano-MgO. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a porous zinc-based composite material doped with magnesium oxide. This method introduces nano-MgO into a Zn-Li-Ca alloy system to obtain a porous zinc-based composite material that possesses excellent mechanical properties, controllable corrosion rate, and good biocompatibility.

[0007] Another object of the present invention is to provide a porous zinc-based composite material doped with magnesium oxide obtained by the above preparation method.

[0008] Another object of the present invention is to provide a bone defect scaffold.

[0009] The objective of this invention is achieved through the following technical solution.

[0010] A method for preparing a porous zinc-based composite material doped with magnesium oxide includes the following steps:

[0011] Step 1: Mix the pore-forming agent and nano-MgO evenly to obtain a composite template material. The ratio of pore-forming agent to nano-MgO by mass is (130~140):3.6. The pore-forming agent is sodium chloride (NaCl).

[0012] In step 1, the particle size of the pore-forming agent is 450~600μm, and the particle size of the nano-MgO is 35~75nm.

[0013] Step 2: Place the composite template material in a mold, pre-press the composite template material under inert gas and 0.04~0.05MPa conditions for 30~40s, then preheat it at 395~400℃ for 37~40min to obtain the preheated template material; pour alloy liquid at 560~570℃ into the preheated template material so that the liquid level of the alloy liquid is higher than the preheated template material, then hold it under inert gas and 0.15~0.3MPa for 1~1.5min, cool it to room temperature, demold it to obtain a blank. The blank containing the pore-forming agent is a porous zinc-based composite material blank. The alloy liquid includes Ca, Zn and Li. By mass, the ratio of Ca, Zn and Li in the alloy liquid is (0.1~0.2):(98~99.2):(0.7~0.8).

[0014] In step 2, the ratio of MgO to alloy liquid in the composite template material is (0.3~0.5):(99.5~99.7) by mass.

[0015] In step 2, the inert gas includes nitrogen and / or argon.

[0016] In step 2, the temperature is increased to 395-400°C at a rate of 8-10°C / min.

[0017] In step 2, the method for preparing the alloy liquid includes: melting pure zinc at 420~450℃ under a protective atmosphere, then adding pure calcium and Zn-Li master alloy, and stirring and smelting at 510~520℃ to obtain the alloy liquid.

[0018] In the above technical solution, the protective atmosphere includes sulfur hexafluoride and nitrogen, and the ratio of sulfur hexafluoride to nitrogen in the protective atmosphere is (1~1.2):3 by volume.

[0019] In the above technical solution, the temperature is increased to 420-450℃ at a rate of 10-12℃ / min, and to 510-520℃ at a rate of 12-15℃ / min.

[0020] Step 3: Remove the pore-forming agent from the porous zinc-based composite material preform. The porous zinc-based composite material preform after removing the pore-forming agent is a porous zinc-based composite material doped with magnesium oxide.

[0021] In step 3, the pore-forming agent is removed by washing, which includes ultrasonic cleaning with acetone, ethanol and water in sequence.

[0022] In step 3, the product is washed and then dried at 27-30°C for 1-1.5 hours.

[0023] The porous zinc-based composite material doped with magnesium oxide obtained by the above preparation method.

[0024] In the above technical solution, the pore size of the porous zinc-based composite material is 120~575 micrometers.

[0025] A bone defect scaffold made of porous zinc-based composite material.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. This invention uses a percolation casting process to uniformly disperse nano-MgO particles on the surface of a pore-forming agent, which is then further mixed with a liquid alloy to obtain a porous zinc-based composite material with nano-MgO adhering to the pore edges. The porous zinc-based composite material of this invention exhibits excellent mechanical properties, corrosion resistance, and biocompatibility.

[0028] 2. The porous zinc-based composite material obtained in this invention has MgO doped at the pore edges. Magnesium oxide not only improves the yield strength but also enhances the surface effect and Mg... 2⁺ Ion release optimizes degradation behavior and biocompatibility. The porous zinc-based composite material exhibits a yield strength of 19.827 MPa and an average annual corrosion rate of 0.1556 mm / year. This invention provides a balanced fabrication method for bone defect scaffolds. Attached Figure Description

[0029] Figure 1 The images show the morphology of the composite template material (pore-forming agent loaded with nano-MgO) in Example 1, where (a) is a morphology image and (b) is a mixed SEM-EDS surface scan image.

[0030] Figure 2 The elemental distribution diagram is shown for the composite template material (pore-forming agent loaded with nano-MgO) in Example 1.

[0031] Figure 3 The morphology and elemental distribution results of the porous zinc-based composite material obtained in Example 1 are shown in (a), (b) is a morphology of nano-MgO at the pore edge, (c) is an enlarged view of the selected part in (b), and (d) is a point scan result of the position indicated by the arrow in (c).

[0032] Figure 4 The pore structure and pore size distribution diagrams of the porous zinc-based composite material obtained in Example 1 are shown in the figure. (a) shows the pore structure in the morphology diagram, and (b) and (c) show the pore size distribution diagrams of the main pores and the connecting pores, respectively.

[0033] Figure 5 The stress-strain curves of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 are shown.

[0034] Figure 6 The stress-strain curves of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 are partially enlarged.

[0035] Figure 7 The average annual corrosion rate of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 is the average value of the average annual corrosion rate.

[0036] Figure 8 The results of in vitro cytotoxicity tests (cell survival rate) of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 are shown. Detailed Implementation

[0037] This invention utilizes a percolation casting process to uniformly disperse nano-MgO particles on the surface of a pore-forming agent, which is then further mixed with a liquid alloy to obtain a porous zinc-based composite material with nano-MgO adhering to the pore edges. The technical solution of this invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0038] In the following examples, the sources of the raw materials are as follows:

[0039] Pure Zn (99.95% purity) and pure Ca (99.95% purity) were both purchased from Shanghai Qichen Industrial Co., Ltd.

[0040] The Zn-3Li master alloy was purchased from Suzhou Chuanmao Metal Materials Co., Ltd. The composition of the Zn-3Li master alloy by mass percentage is: 97% Zn and 3% Li.

[0041] Sodium chloride (99.99% purity, granules) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0042] Sulfur hexafluoride (purity 99.99 wt%) was purchased from Tianjin Saimet Special Gases Co., Ltd.

[0043] Nitrogen (99.99 wt% purity) was purchased from Tianjin Huanyu Gas Co., Ltd.

[0044] Chromium trioxide (purity ≥99%), silver nitrate (purity ≥99%), and barium nitrate (purity ≥99%) were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0045] Preparation method of nano-MgO (particles): 0.1 g of hexadecyltrimethylammonium bromide (CTAB) and 10 mL of deionized water were mixed evenly to obtain a hexadecyltrimethylammonium bromide solution. 250 mL of deionized water was heated to 40 °C in a water bath, and then 73.26 g of MgCl2 was added and dissolved completely to obtain a MgCl2 solution. The hexadecyltrimethylammonium bromide solution was added dropwise to the MgCl2 solution, and the mixture was stirred at 600 r / min for 20 minutes. Then, 23.64 g of oxalic acid was added, and the mixture was stirred at 600 r / min for 20 minutes to allow the reaction to proceed. The mixture was then vacuum filtered to obtain a precipitate. The process of adding anhydrous ethanol, stirring thoroughly, and then filtering was repeated three times to obtain a solid. The solid was dried in a drying oven to obtain a blocky solid (magnesium oxalate). The blocky solid was sintered in a muffle furnace at 600 °C for 8 hours, sieved through a 400-mesh sieve, and ground to obtain nano-MgO. The nano-MgO has a particle size range of 35~75nm and an average particle size of 50nm. For details on the preparation method of nano-MgO, please refer to section 2.1.1 of: Preparation and In Vitro Degradation Behavior of Biomedical Mg-Zn-Ca-xMgO Composite Materials and Their Coatings [D]. Tianjin University of Technology, 2020.D01:10.27360 / d.cnki.gtlgy.2020.000363.

[0046] Example 1

[0047] A method for preparing a porous zinc-based composite material doped with magnesium oxide includes the following steps:

[0048] Step 1: Mix the pore-forming agent and nano-MgO, and sonicate in an ultrasonic machine (ultrasonic frequency 70Hz) for 10 minutes to uniformly load the nano-MgO onto the surface of the pore-forming agent, thus obtaining a composite template material (pore-forming agent loaded with nano-MgO). The ratio of pore-forming agent to nano-MgO by mass is 140:3.6, and the pore-forming agent is sodium chloride (the particle size of the pore-forming agent is 450~600μm, and the average particle size of the pore-forming agent is 550μm).

[0049] Step 2: Pour the composite template material into a mold with an open top (the mold contains a cylindrical cavity, with the composite template material filling approximately 10% of the cavity; the mold is made of steel). Pre-press the composite template material for 35 seconds under inert gas (argon) at 0.05 MPa. Then, heat the material to 400°C at a rate of 10°C / min and preheat it at 400°C for 40 minutes to obtain the preheated template material in the mold. Quickly pour molten alloy at 560°C into the preheated template material, ensuring the alloy liquid level is higher than the preheated template material. Immediately afterward, introduce argon gas and maintain the pressure at 0.15 MPa for 1.5 minutes. The molten metal in the alloy liquid is fully penetrated into the gaps of the pore-forming agent under gas pressure to form a continuous metal matrix. After the alloy liquid cools naturally to room temperature, it is demolded to obtain a billet. The lower part of the billet contains the pore-forming agent, while the upper part does not. The billet containing the pore-forming agent and the billet without the pore-forming agent are cut and separated. The billet containing the pore-forming agent is a porous zinc-based composite material billet. The ratio of MgO to alloy liquid in the composite template material is 0.3:99.7 by mass. The alloy liquid includes Ca, Zn, and Li, and the ratio of Ca, Zn, and Li in the alloy liquid is 0.1:99.1:0.8 by mass.

[0050] The method for preparing the alloy liquid includes: placing pure zinc (matrix) in a graphite crucible, then placing the graphite crucible in a vacuum atmosphere melting furnace (model MTC-5EA, purchased from Tianjin Magnesium Technology Co., Ltd.), introducing a protective atmosphere, heating to 430℃ at a rate of 12℃ / min to melt the pure zinc, then adding pure calcium and Zn-Li master alloy, heating to 510℃ at a rate of 13℃ / min and stirring and melting at 510℃ for 5min to uniformly disperse the pure calcium and Zn-Li master alloy in the pure zinc, thus obtaining the alloy liquid (Zn-Li-Ca alloy system). The protective atmosphere is a mixture of sulfur hexafluoride and nitrogen, and the ratio of sulfur hexafluoride to nitrogen in the protective atmosphere is 1:3 by volume (the flow rates of sulfur hexafluoride and nitrogen are 0.1MPa / min and 0.3MPa / min, respectively).

[0051] Step 3: The porous zinc-based composite material preform is ultrasonically treated with acetone, ethanol and water for 30 min in sequence to remove the pore-forming agent, and then dried at 27℃ for 1 h to obtain a cylindrical porous zinc-based composite material (Zn-0.8Li-0.1Ca / 0.3MgO) doped with magnesium oxide.

[0052] The composite template material (pore-forming agent loaded with nano-MgO) of Example 1 was subjected to SEM and EDS tests, and the resulting morphology images are shown below. Figure 1 As shown in (a), Figure 1 (b) is a hybrid SEM-EDS area scan image, with element distribution as follows: Figure 2 As shown, Figure 2The image shows the elemental distribution of Mg, O, Cl, and Na. As can be seen from the morphology diagram, the composite template material of Example 1 is generally ellipsoidal, with fine particles uniformly dispersed on its surface. Based on the elemental distribution diagram, the fine particles are nano-MgO, and these nano-MgO particles are relatively uniformly attached to the surface of NaCl.

[0053] The porous zinc-based composite material obtained in Example 1 was subjected to ultra-high resolution field emission scanning electron microscopy (UHEM) testing, and the obtained UHEM images are shown below. Figure 3 As shown in the figure, (a) is a morphology image of nano-MgO at the pore edge, (b) is an enlarged view of the area selected in (a), (c) is an enlarged view of the area selected in (b), and (d) is the spot scan result at the location indicated by the arrow in (c). From the morphology images, it can be seen that the magnesium oxide in the porous zinc-based composite material obtained in Example 1 is uniformly distributed at the edge of the porous structure. According to... Figure 3 As shown in (d), the ratio of Mg to O in the porous zinc-based composite material obtained in Example 1 is close to 1:1, and the source of Mg is only nano-MgO, indicating that nano-MgO was successfully doped into the alloy liquid. This shows that magnesium oxide was successfully doped into the porous zinc-based composite material obtained in Example 1.

[0054] Figure 4 The diagram shows the pore structure and pore size distribution of the porous zinc-based composite material obtained in Example 1. In (a), the pore structure is shown in the morphology diagram, with the larger frame representing the main pores of the porous zinc-based composite material and the smaller frame representing the connecting pores (connecting channels between the main pores); (b) and (c) are the pore size distribution diagrams of the main pores and connecting pores, respectively. According to the pore size distribution diagrams of the porous zinc-based composite material, the average pore size of the main pores in the porous zinc-based composite material obtained in Example 1 is 510.21 ± 61.10 μm, and the average pore size of the connecting pores is 156.21 ± 28.07 μm. The pore size distribution is relatively concentrated, indicating good mechanical properties.

[0055] The porosity of the porous zinc-based composite material obtained in Example 1 was 64% by weighing, indicating that the porous zinc-based composite material of the present invention has a porous structure.

[0056] Comparative Example 1

[0057] A method for preparing a porous zinc-based composite material (Zn-0.8Li-0.1Ca) is basically the same as that in Example 1, except that the composite template material in step 1 does not contain nano-MgO. The ratio of the composite template material to the alloy liquid is 13:120 by mass.

[0058] Comparative Example 2

[0059] A method for preparing a porous zinc-based composite material is basically the same as the method for preparing a magnesium oxide-doped porous zinc-based composite material in Example 1, with the only difference being the alloy liquid and the composite template material. The alloy liquid includes Ca, Zn, Li, and MgO, and the mass ratio of Ca, Zn, Li, and MgO in the alloy liquid is 0.1:98.8:0.8:0.3. The composite template material contains only a pore-forming agent (sodium chloride). The mass ratio of the composite template material to the alloy liquid is 13:120.

[0060] The method for obtaining the alloy liquid includes: placing pure zinc in a graphite crucible, then placing the graphite crucible in a vacuum atmosphere melting furnace, introducing a protective atmosphere, heating to 430°C at a rate of 12°C / min to melt the pure zinc, then adding pure calcium, Zn-Li master alloy and nano MgO, heating to 510°C at a rate of 13°C / min and stirring and melting at 510°C for 5 min, so that the pure calcium, Zn-Li master alloy and nano MgO are uniformly dispersed in the pure zinc, and an alloy liquid containing MgO is obtained.

[0061] In Comparative Example 2, nano-MgO was first mixed with a matrix (pure zinc), pure calcium, and a Zn-Li master alloy, and then smelted to obtain an alloy liquid.

[0062] Example 2

[0063] Mechanical Properties: To evaluate the mechanical properties of the porous zinc-based composite material, a cylindrical (10mm diameter × 15mm height) porous zinc-based composite material was placed on a DDL10 universal testing machine (purchased from Changchun Mechanical Science Research Institute Co., Ltd.). A compression test was conducted at room temperature along the height direction at a rate of 0.5mm / min. The test was stopped when the strain reached 40%, and data were collected to output the stress-strain curve. The porous zinc-based composite material used was one of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2. The stress-strain curve of the porous zinc-based composite material is shown below. Figure 5 As shown.

[0064] Based on the stress-strain curve from the compression experiment, the 0.2 offset method (such as...) is used. Figure 6 As shown, a point with a strain of 0.2% is selected, and a straight line parallel to the elastic deformation stage is drawn. The ordinate value corresponding to the intersection of this line and the stress-strain curve is the yield strength. The elastic modulus is obtained by fitting the linear portion of the initial elastic segment of the stress-strain curve, and the slope of this straight line is taken as the elastic modulus. The yield strength and elastic modulus of the porous zinc-based composite material were measured. Figure 5 and Figure 6It can be seen that the coordinates of the intersection points of the stress-strain curves of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 with the straight line parallel to the elastic deformation stage are (2.997, 19.827), (2.169, 9.182), and (2.508, 11.610), respectively. The yield strength of the porous zinc-based composite material obtained in Example 1 is 19.827 MPa, and the elastic modulus is 0.71 GPa; the yield strength of the porous zinc-based composite material obtained in Comparative Example 1 is 9.182 MPa, and the elastic modulus is 0.466 GPa; the yield strength of the porous zinc-based composite material obtained in Comparative Example 2 is 11.610 MPa, and the elastic modulus is 0.503 GPa. The yield strength of the porous zinc-based composite material obtained in Example 1 is greater than that of Comparative Example 1 and Comparative Example 2, which may be attributed to the formation of a second phase (mainly β-LiZn4 phase and CaZn) in the porous zinc-based composite material obtained in Example 1. 13 The addition of nano-MgO refines the β-LiZn4 phase in the second phase, thereby inducing the strengthening of the second phase and significantly improving the mechanical properties.

[0065] Example 3

[0066] Corrosion performance: First, weigh the sample to be tested and record it as the initial weight (m0). Immerse the sample in a centrifuge tube containing 110 mL of SBF solution (the composition of SBF solution is detailed in Table 1). Then place the centrifuge tube in a constant temperature shaker at 37℃ (speed 70 r / min) and soak the sample in SBF solution for 28 days. On day T of soaking (T=7, 14 and 28), take out the sample, clean the surface with anhydrous ethanol, dry it at 27℃ for 0.5 h, and then soak it in 5 mL of chromic acid solution for 1.5 min to remove the corrosion products on the surface. The corroded sample is obtained by rinsing the surface of the corroded sample with anhydrous ethanol, drying it with a hair dryer, weighing it, and recording it as the post-corrosion weight (m1). Calculate the average annual corrosion rate using the formula. The chromic acid solution is a mixture obtained by dissolving 18g of chromium trioxide, 1g of silver nitrate and 1g of barium nitrate in 100mL of deionized water and stirring in the dark for 25min; the sample to be tested is one of the porous zinc-based composite materials (circular discs with a diameter of 10mm and a thickness of 2mm) obtained in Example 1, Comparative Example 1 and Comparative Example 2.

[0067] formula:

[0068]

[0069] Where m0 is the initial weight (g), m1 is the weight after corrosion (g); ρ is the density of the sample; A is the surface area of ​​the sample (550 mm²). 2 T represents the soaking time (year).

[0070] Each sample was tested in triplicate, and the average annual corrosion rate was calculated.

[0071] Preparation method of SBF solution: Under 37°C, the materials in Table 1 were mixed with 1L of distilled water until homogeneous to obtain a mixed system. The pH of the mixed system was adjusted to 7.4 using hydrochloric acid (HCl concentration of 36~38wt%) to obtain SBF solution. All materials in Table 1 are of analytical grade. The materials used to prepare SBF solution and their mass are detailed in Table 1.

[0072] Table 1

[0073]

[0074] The curves showing the average annual corrosion rate of the porous zinc-based composite materials obtained in Examples 1, 1, and 2 as a function of time are as follows: Figure 7 As shown. By Figure 7 It can be seen that on the 7th day of soaking ( Figure 7 During the first week of immersion, the average annual corrosion rates of the porous zinc-based composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 were 0.1556 mm / year, 0.0801 mm / year, and 0.1153 mm / year, respectively. Furthermore, the average annual corrosion rate of the porous zinc-based composite material obtained in Example 1 was greater than that of Comparative Example 1 and Comparative Example 2 after 28 days of immersion. This may be because the porous zinc-based composite material of Example 1, doped with nano-MgO, induces CaZn corrosion due to the incorporation of nano-MgO. 13 Phase separation and coarsening. The separated CaZn... 13 The phase forms extensive electrochemical couples with the Zn matrix, generating a potential difference that drives electrochemical corrosion. Compared to the porous zinc-based composite material in Comparative Example 2, which disperses nano-MgO in the matrix, the method for preparing the porous zinc-based composite material of this invention increases the number of corrosion sites by uniformly distributing nano-MgO at the pore edges, and since corrosion mostly starts from the pore edges, the corrosion rate is improved.

[0075] For biodegradable metallic materials used in large bone defects, the degradation rate of magnesium-based materials typically ranges from 0.15 to 0.5 mm / year. However, most zinc-based alloys in current technologies have an average annual corrosion rate below 0.15 mm / year. Large bone defects involve long repair cycles and slow bone regeneration. If the zinc matrix corrodes too slowly, it can occupy the bone defect space for an extended period, hindering new bone growth. Appropriately increasing the corrosion rate can simultaneously match the space requirements for new bone formation, avoiding stress shielding caused by scaffold residue. Therefore, it is necessary to appropriately increase the average annual corrosion rate of zinc-based alloys to achieve better clinical application results.

[0076] Example 4

[0077] To investigate the effect of porous zinc-based composite materials on the survival of mouse osteoblast precursor cells, mouse osteoblast precursor cells MC3T3-E1 (ATCC CRL-2594™, purchased from Wuhan Pronosai Life Science Technology Co., Ltd.) were selected as model cells for in vitro cytotoxicity evaluation.

[0078] Preparation of the cell stock solution: 1 mL of frozen cells was placed in 7 mL of liquid culture medium and then cultured in a humidified incubator at 37°C and 5% CO2 for one week to obtain the cell stock solution. The frozen cells were mouse osteoblast precursor cells MC3T3-E1. The liquid culture medium was a mixture of fetal bovine serum (Gibco, purchased from Thermo Fisher Scientific, Inc.), penicillin-streptomycin (Gibco, purchased from Thermo Fisher Scientific, Inc.), and α-MEM medium (Genview, purchased from Beijing Dingguo Changsheng Biotechnology Co., Ltd.). By volume, the ratio of fetal bovine serum, penicillin-streptomycin, and α-MEM medium in the liquid culture medium was 10:1:89.

[0079] Preparation of the extract: The porous zinc-based composite material was sterilized with ultraviolet light for 3 hours, then immersed in 7 mL of liquid culture medium, and transferred to a humidified incubator at 37°C and 5% CO2 for constant temperature extraction for 3 days to obtain the extract. The porous zinc-based composite material is one of the porous zinc-based composite materials (circular discs with a diameter of 10 mm × a thickness of 2 mm) obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0080] Take 8 mL of the cell stock solution and place it in a centrifuge tube. Centrifuge at 1500 rpm for 5 min, discard the supernatant, and obtain the first cell cluster. Add liquid culture medium to the first cell cluster to dilute to a viable cell concentration of (8 ± 0.5) × 10⁻⁶. 4 The cell density was measured at 100 μL / mL to obtain the first liquid. 100 μL of the first liquid was added to each well of a 96-well plate for seeding. The 96-well plate was then transferred to a humidified incubator at 37°C and 5% CO2 for 24 h to obtain the second liquid containing adherent cells. The liquid culture medium in the second liquid was removed using a pipette. 100 μL of PBS (pH=7.3±0.1) was added to each well of the 96-well plate containing adherent cells for washing. After removing the PBS, the second cell cluster was obtained.

[0081] Blank control group: 100 μL of liquid culture medium was added to each well of a 96-well plate containing the second cell cluster. The 96-well plates were then incubated at 37°C and 5% CO2 for 1, 3, or 5 days to obtain the first system. 10 μL of CCK-8 reagent (Biosharp, purchased from Beijing Lanjieke Technology Co., Ltd.) was added to the first system, and the plate was incubated at 37°C and 5% CO2 for 1 hour to obtain the blank test solution. The blank test solution obtained after 1 day of incubation was designated as Blank Test Solution-1; the blank test solution obtained after 3 days of incubation was designated as Blank Test Solution-3; and the blank test solution obtained after 5 days of incubation was designated as Blank Test Solution-5.

[0082] Experimental group: 100 μL of the diluted extract (a mixture of extract and liquid culture medium, with a volume ratio of 1:2) was added to each well of a 96-well plate containing the second cell cluster. The plate was then incubated at 37°C and 5% CO2 for 1, 3, or 5 days to obtain the second system. 10 μL of CCK-8 reagent was added to the second system, and the plate was incubated at 37°C and 5% CO2 for 1 hour to obtain the test solution. The test solution obtained after 1 day of incubation was designated as Test Solution-1; the test solution obtained after 3 days of incubation was designated as Test Solution-3; and the test solution obtained after 5 days of incubation was designated as Test Solution-5.

[0083] The absorbance of the blank and experimental test solutions at 450 nm was measured using a Bio-RAD 680 microplate reader to obtain the absorbance (OD) of the blank group. B ) and the absorbance of the experimental group (OD) E ), and then through RGR=OD E / OD B Calculate cell viability (RGR, %). The blank test solution is blank test solution-1, blank test solution-3 or blank test solution-5, and the corresponding experimental test solutions are experimental test solution-1, experimental test solution-3 or experimental test solution-5 respectively.

[0084] The in vitro cytotoxicity test results of the porous zinc-based composite materials obtained in Examples 1, 1, and 2 against mouse osteoblast progenitor cells MC3T3-E1 are as follows: Figure 8 As shown. By Figure 8It can be seen that the cell survival rate increases with the increase of culture days. After 1 day of culture, the cell survival rate in the experimental group constructed with the extract obtained from the porous zinc-based composite material of Example 1 was 104.8%, which is higher than the cell survival rates in the experimental groups constructed with the extract obtained from the porous zinc-based composite material of Comparative Examples 1 and 2 (98.2% and 102.5%, respectively). After 5 days of culture, the cell survival rate in the experimental group constructed with the extract obtained from the porous zinc-based composite material of Example 1 reached as high as 135.7%, while the cell survival rates in the experimental groups constructed with the extract obtained from the porous zinc-based composite material of Comparative Examples 1 and 2 were 118.4% and 126.4%, respectively. Therefore, within 5 days of culture, the cell survival rate in the experimental group obtained in Example 1 is better than that in Comparative Examples 1 and 2. This may be attributed to the addition of nano-MgO promoting cell proliferation, resulting in a cell survival rate greater than 1 and higher than that in Comparative Examples 1 and 2. This indicates that the preparation method of the present invention improves the biocompatibility of the obtained porous zinc-based composite material by combining nano-MgO with a pore-forming agent and further introducing it into the alloy liquid.

[0085] This suggests that in a physiological fluid environment, the preferential corrosion of the microenvironment created by nano-MgO particles is more favorable for cell adsorption, proliferation, and growth within the porous zinc-based composite material and its pores. Furthermore, the Mg released during the degradation of MgO... 2 ⁺ ions further promote cell migration, proliferation, and angiogenesis. The preparation method of this invention ensures that MgO is uniformly distributed on the surface of the pores, further increasing Mg content. 2+ The amount increases biocompatibility.

[0086] This invention successfully introduces a porous structure by attaching nano-MgO particles to a pore-forming agent, allowing the MgO particles to be precisely distributed at the pore edges, thus avoiding the defects of uneven aggregation caused by direct doping. The nano-MgO distributed at the pore edges can refine grain size, improve mechanical properties, release magnesium ions to promote bone regeneration and angiogenesis, and optimize degradation rate, simultaneously improving problems such as insufficient mechanical strength, degradation mismatch, and weak bioactivity. This has significant value in overcoming existing technological bottlenecks and promoting the clinical translation of materials.

[0087] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a porous zinc-based composite material doped with magnesium oxide, characterized in that, Includes the following steps: Step 1: Mix the pore-forming agent and nano-MgO evenly to obtain a composite template material. The ratio of pore-forming agent to nano-MgO by mass is (130~140):3.

6. The pore-forming agent is sodium chloride. Step 2: Place the composite template material in a mold, pre-press the composite template material under inert gas and 0.04~0.05MPa conditions for 30~40s, then preheat it at 395~400℃ for 37~40min to obtain the preheated template material; pour alloy liquid at 560~570℃ into the preheated template material so that the liquid level of the alloy liquid is higher than the preheated template material, then hold it under inert gas and 0.15~0.3MPa for 1~1.5min, cool it to room temperature, demold it to obtain a blank. The blank containing the pore-forming agent is a porous zinc-based composite material blank. The alloy liquid includes Ca, Zn and Li. By mass, the ratio of Ca, Zn and Li in the alloy liquid is (0.1~0.2):(98~99.2):(0.7~0.8). Step 3: Remove the pore-forming agent from the porous zinc-based composite material preform. The porous zinc-based composite material preform after removing the pore-forming agent is a porous zinc-based composite material doped with magnesium oxide.

2. The preparation method according to claim 1, characterized in that, In step 1, the particle size of the pore-forming agent is 450~600μm, and the particle size of the nano-MgO is 35~75nm.

3. The preparation method according to claim 1, characterized in that, In step 2, the ratio of MgO to alloy liquid in the composite template material is (0.3~0.5):(99.5~99.7) by mass.

4. The preparation method according to claim 1, characterized in that, In step 2, the inert gas includes nitrogen and / or argon. The temperature is increased to 395-400℃ at a rate of 8-10℃ / min.

5. The preparation method according to claim 1, characterized in that, In step 2, the method for preparing the alloy liquid includes: melting pure zinc at 420~450℃ under a protective atmosphere, then adding pure calcium and Zn-Li master alloy, and stirring and smelting at 510~520℃ to obtain the alloy liquid.

6. The preparation method according to claim 5, characterized in that, The protective atmosphere consists of sulfur hexafluoride and nitrogen, with the ratio of sulfur hexafluoride to nitrogen in the protective atmosphere being (1~1.2):3 by volume. The temperature is increased to 420-450°C at a rate of 10-12°C / min, and then increased to 510-520°C at a rate of 12-15°C / min.

7. The preparation method according to claim 1, characterized in that, In step 3, the pore-forming agent is removed by washing, which includes ultrasonic cleaning with acetone, ethanol and water in sequence. After washing, dry at 27~30℃ for 1~1.5 hours.

8. The porous zinc-based composite material doped with magnesium oxide obtained by the preparation method according to any one of claims 1 to 7.

9. The pore size of the porous zinc-based composite material as described in claim 8 is 120~575 micrometers.

10. A bone defect scaffold, characterized in that, The bone defect scaffold is made of the porous zinc-based composite material as described in claim 8.

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