Preparation method of porous magnesium-zinc-calcium-silver alloy for bone repair

Abstract

The invention discloses a preparation method of a porous magnesium-zinc-calcium-silver alloy for bone repair, and the porous magnesium alloy is prepared from an Mg-Zn-Ca-Ag alloy by adopting a gas phase dealloying process. Wherein the Ca element is added, so that when the magnesium alloy is used as a bone repair material, the bone growth rate is increased, and bone tissue growth can be promoted; the Zn element has a remarkable inhibiting effect on common pathogenic bacteria such as staphylococcus aureus and escherichia coli by destroying a bacterial membrane structure and inhibiting formation of a biological membrane, and the infection risk is reduced; the unique antibacterial property of the Ag element is more beneficial to the application of the bone repair material; meanwhile, in the dealloying process, the pore size and the porosity can be controlled by controlling the two experimental parameters of the temperature and the vacuum degree, and compared with other methods for preparing the porous magnesium alloy, the method is more efficient, low in cost and beneficial to large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of biomaterial preparation and processing, and in particular to a method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair. Background Art

[0002] As a lightweight alloy material, magnesium alloys offer excellent properties such as low cost and high specific strength, making them widely used in aerospace, electronics, and biomedicine. Because the density of magnesium and its alloys is very similar to that of human bone, they effectively prevent stress shielding and readily degrade without producing harmful substances when implanted in vivo. These properties make magnesium-based materials promising for bone tissue engineering applications. However, conventional magnesium alloys suffer from insufficient antibacterial and anti-infective properties and lack of osteogenesis-promoting activity, limiting their application in bone tissue engineering. Therefore, the development of new magnesium alloys to promote their application in bone repair materials is crucial. Among the many new magnesium alloys, porous magnesium alloys possess a larger specific surface area, providing more osteoconductive surface for bone cells, which is more conducive to bone tissue growth. Furthermore, the pore size and distribution of porous magnesium alloys facilitate the excretion of corrosion products. Furthermore, porous surfaces promote osteoblast adhesion, proliferation, and differentiation (e.g., a 1.5-fold increase in ALP activity) and can be loaded with growth factors (such as BMP-2 and VEGF) to enhance bone regeneration.

[0003] Therefore, the present invention aims to provide a method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair. Summary of the Invention

[0004] To address the above technical problems, the present invention utilizes a vapor-phase dealloying process to prepare a porous magnesium alloy. Other metal elements, such as Zn, Ca, and Ag, are added to the molten magnesium metal and completely dissolved into the alloy. The resulting slurry is then mixed and stirred to achieve a uniform blend, then poured into a mold and cooled. The resulting alloy is then subjected to vapor-phase dealloying to obtain a porous magnesium alloy with a pore size and porosity suitable for bone repair.

[0005] In order to achieve the above technical effects, the present invention is implemented by the following technical solutions: A method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair, characterized in that it comprises the following steps:

[0006] S1. Melting magnesium metal in a melting furnace at a temperature of 740-760°C, then adding Zn, Ca, and Ag elements, and continuing to heat the melting furnace to completely melt Zn, Ca, and Ag in the magnesium metal solution to obtain an alloy slurry;

[0007] S2. The obtained alloy slurry is mixed uniformly, and then cast into a mold at a constant temperature in a furnace, and naturally cooled at room temperature in the furnace to obtain a Mg-Zn-Ca-Ag alloy after solidification;

[0008] S3. Performing vapor phase dealloying treatment on the Mg-Zn-Ca-Ag alloy obtained after cooling to obtain a porous Mg-Zn-Ca-Ag alloy for bone repair.

[0009] Furthermore, in S1, the content of Zn in the alloy slurry is 0.5 wt%, the content of Ca is 0.3 wt%, the content of Ag is 5 wt%, and the balance of Mg in the alloy slurry is 94.2 wt%.

[0010] Furthermore, in S2, the mold is a rectangle of 25 mm × 15 mm × 50 mm.

[0011] Furthermore, in S3, the vapor phase dealloying treatment is specifically as follows:

[0012] S3.1. Place the obtained Mg-Zn-Ca-Ag alloy into a tube furnace;

[0013] S3.2, then evacuate the tube furnace to a vacuum degree of 10 -1 Pa~10 -3 Pa;

[0014] S3.3. Then heat the tube furnace to 550°C-600°C and then keep the temperature for 1 hour to obtain the bone repair porous magnesium-zinc-calcium-silver alloy.

[0015] The beneficial effects of the present invention are:

[0016] 1. The present invention adopts a composite process of alloying and vapor-phase dealloying to prepare porous magnesium alloys. During this process, Zn, Ca, and Ag elements are added, which makes the porous magnesium alloy have better mechanical strength and corrosion resistance when used as a bone repair material. During this process, the slurry composition is homogenized by stirring and mixing, which provides a good foundation for subsequent preparation.

[0017] 2. The present invention adopts a gas phase dealloying method to prepare porous magnesium alloy. After the alloy melt solidifies and cools, the alloy is gas phase dealloyed. The gas phase dealloying temperature is 550℃-600℃ and the vacuum degree is 10 -1 Pa~10 -3 Pa; the pore size and porosity of the obtained alloy are conducive to the growth process of bone tissue and are more suitable for use as bone repair materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a flow chart of the preparation method of the porous magnesium-zinc-calcium-silver alloy for bone repair of the present invention;

[0020] Figure 2 Schematic diagram of the mold structure of the present invention;

[0021] Figure 3 This is a gas phase dealloyed pore size diagram of the bone repair porous Mg-Zn-Ca-Ag alloy prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair comprises the following steps:

[0025] S1. First, magnesium metal is heated to melt in a smelting furnace, and then Zn, Ca, and Ag elements are added. The smelting furnace is further heated to completely melt Zn, Ca, and Ag to obtain an alloy slurry, wherein the added Zn content is 0.5wt%, the Ca content is 0.3wt%, the Ag content is 5wt%, and the balance is Mg;

[0026] S2. The obtained alloy slurry is mixed uniformly, and then the alloy slurry is cast into a mold with a size of 25 mm × 15 mm × 50 mm under a constant temperature condition in a furnace, and naturally cooled at room temperature in the furnace to obtain a Mg-Zn-Ca-Ag alloy after solidification;

[0027] S3, then carry out gas phase dealloying treatment, the dealloying temperature is 600 ℃, the vacuum degree is 10 -3 Pa, and the time is 1h, a porous Mg-Zn-Ca-Ag alloy for bone repair with a pore size of 40μm and a porosity of 80% can be obtained.

[0028] The obtained bone repair porous magnesium-zinc-calcium-silver alloy was immersed in SBF human body simulation fluid for 12 weeks, and subjected to simulated pressure in human bones to observe its degradation rate and structural changes during this period. The obtained alloy was able to maintain a specific three-dimensional structure during this period, and after testing, it can be used as a conduction mechanism for bone cells. At the same time, the degradation rate is equivalent to the rate of new bone formation. However, it is completely degraded at 10 weeks and 2 days, which cannot guarantee the complete healing of the wound.

[0029] Example 2

[0030] A method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair comprises the following steps:

[0031] S1. First, magnesium metal is heated to melt in a smelting furnace, and then Zn, Ca, and Ag elements are added, and the smelting furnace is continued to melt Zn, Ca, and Ag completely to obtain an alloy slurry, wherein the added Zn content is 0.5wt%, the Ca content is 0.3wt%, the Ag content is 5wt%, and the balance is Mg;

[0032] S2. The obtained alloy slurry is mixed uniformly, and then the alloy slurry is cast into a mold with a size of 25 mm × 15 mm × 50 mm under a constant temperature condition in a furnace, and naturally cooled at room temperature in the furnace to obtain a Mg-Zn-Ca-Ag alloy after solidification;

[0033] S3, then carry out gas phase dealloying treatment, the dealloying temperature is 600 ℃, the vacuum degree is 10 -2 Pa, and the time is 1h, a porous Mg-Zn-Ca-Ag alloy for bone repair with a pore size of 20μm and a porosity of 75% can be obtained.

[0034] The obtained bone repair porous magnesium-zinc-calcium-silver alloy was immersed in SBF human simulation fluid for 12 weeks, and subjected to simulated pressure in human bones to observe its degradation rate and structural changes during this period. The obtained alloy was able to maintain a specific three-dimensional structure during this period, and after testing, it can be used as a conduction mechanism for bone cells. At the same time, the degradation rate is equivalent to the rate of new bone formation. However, it was completely degraded at 10 weeks and 5 days, which cannot guarantee the complete healing of the wound.

[0035] Example 3

[0036] A method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair comprises the following steps:

[0037] S1. First, magnesium metal is heated to melt in a smelting furnace, and then Zn, Ca, and Ag elements are added, and the smelting furnace is continued to melt Zn, Ca, and Ag completely to obtain an alloy slurry, wherein the added Zn content is 0.5wt%, the Ca content is 0.3wt%, the Ag content is 5wt%, and the balance is Mg;

[0038] S2. The obtained alloy slurry is mixed uniformly, and then the alloy slurry is cast into a mold with a size of 25 mm × 15 mm × 50 mm under a constant temperature condition in a furnace, and naturally cooled at room temperature in the furnace to obtain a Mg-Zn-Ca-Ag alloy after solidification;

[0039] S3, then carry out gas phase dealloying treatment, the dealloying temperature is 550 ℃, the vacuum degree is 10 -3 Pa, and the time is 1h, a porous Mg-Zn-Ca-Ag alloy for bone repair with a pore size of 25μm and a porosity of 77.5% can be obtained.

[0040] The obtained bone repair porous magnesium-zinc-calcium-silver alloy was immersed in SBF human body simulation fluid for 12 weeks, and was subjected to simulated pressure in human bones to observe its degradation rate and structural changes during this period. The obtained alloy was able to maintain a specific three-dimensional structure during this period, and after testing, it can be used as a conduction mechanism for bone cells. At the same time, the degradation rate is equivalent to the rate of new bone formation. However, it is completely degraded at 11 weeks, and its wound cannot be completely healed.

[0041] Example 4

[0042] A method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair comprises the following steps:

[0043] S1. First, magnesium metal is heated to melt in a smelting furnace, and then Zn, Ca, and Ag elements are added, and the smelting furnace is continued to melt Zn, Ca, and Ag completely to obtain an alloy slurry, wherein the added Zn content is 0.5wt%, the Ca content is 0.3wt%, the Ag content is 5wt%, and the balance is Mg;

[0044] S2. The obtained alloy slurry is mixed uniformly, and then the alloy slurry is cast into a mold with a size of 25 mm × 15 mm × 50 mm under a constant temperature condition in a furnace, and naturally cooled at room temperature in the furnace to obtain a Mg-Zn-Ca-Ag alloy after solidification;

[0045] S3, then carry out gas phase dealloying treatment, the dealloying temperature is 550 ℃, the vacuum degree is 10 -2 Pa, and the time is 1h, a porous Mg-Zn-Ca-Ag alloy for bone repair with a pore size of 6μm and a porosity of 70% can be obtained.

[0046] The obtained bone repair porous magnesium-zinc-calcium-silver alloy was immersed in SBF human body simulation fluid for 12 weeks, and was subjected to simulated pressure in human bones to observe its degradation rate and structural changes during this period. The obtained alloy was able to maintain a specific three-dimensional structure during this period, and after testing, it can be used as a conduction mechanism for bone cells. At the same time, the degradation rate is equivalent to the rate of new bone formation, and it is completely degraded in 12 weeks, ensuring that the wound is completely healed and no residue remains in the human body.

[0047] Example 5

[0048] According to Examples 1-4, when the content of Zn is 0.5wt%, the content of Ca is 0.3wt%, the content of Ag is 5wt%, and the balance is Mg, the dealloying temperature is 550℃, and the vacuum degree is 10 -2 Pa, time is 1h, a bone repair porous Mg-Zn-Ca-Ag alloy with a pore size of 6μm and a porosity of 70% can be obtained; the obtained bone repair porous Mg-Zn-Ca-Ag alloy has better mechanical properties, corrosion resistance and biocompatibility, and is more conducive to the repair of bone tissue.

[0049] In addition, in the present invention, the addition of Zn, Ca, and Ag elements to magnesium metal can change the electrode potential of its alloy, regulate its corrosion rate, and at the same time regulate the changes in its microstructure, effectively improving the load-bearing capacity of bone and promoting the formation of new bone. In addition, Zn has a significant inhibitory effect on common pathogens such as Staphylococcus aureus and Escherichia coli by destroying the bacterial membrane structure and inhibiting biofilm formation, reducing the risk of infection. The addition of Ca element increases the rate of bone growth when magnesium alloy is used as a bone repair material and can promote bone tissue growth. The unique antibacterial properties of Ag element are more conducive to the application of bone repair materials. At the same time, as the implant degrades, accompanied by the reduction of the mechanical properties of the implant material, the load will gradually be transferred from the implant to the human bone and soft tissue, thereby avoiding the stress shielding effect.

[0050] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all details in detail, nor do they limit the invention to only the specific implementation methods described.

Claims

1. A method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair, characterized in that: The following steps are involved: S1. Melting magnesium metal in a melting furnace at a temperature of 740-760°C, then adding Zn, Ca, and Ag elements, and continuing to heat the melting furnace to completely melt Zn, Ca, and Ag in the magnesium metal solution to obtain an alloy slurry; S2. The obtained alloy slurry is mixed uniformly, and then cast into a mold at a constant temperature in a furnace, and naturally cooled at room temperature in the furnace to obtain a Mg-Zn-Ca-Ag alloy after solidification; S3. Performing vapor phase dealloying treatment on the Mg-Zn-Ca-Ag alloy obtained after cooling to obtain a porous Mg-Zn-Ca-Ag alloy for bone repair.

2. The method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair according to claim 1, characterized in that: In S1, the content of Zn in the alloy slurry is 0.5 wt%, the content of Ca is 0.3 wt%, the content of Ag is 5 wt%, and the balance of Mg in the alloy slurry is 94.2 wt%.

3. The method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair according to claim 1, characterized in that: In S2, the mold is a rectangle of 25mm×15mm×50mm.

4. The method for preparing a porous magnesium-zinc-calcium-silver alloy for bone repair according to claim 1, characterized in that: In S3, the vapor phase dealloying treatment is specifically as follows: S3.

1. Place the obtained Mg-Zn-Ca-Ag alloy into a tube furnace; S3.2, then evacuate the tube furnace to a vacuum degree of 10 -1 Pa~10 -3 Pa; S3.

3. Then heat the tube furnace to 550°C-600°C and then keep the temperature for 1 hour to obtain the porous magnesium-zinc-calcium-silver alloy for bone repair.

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