BIOCOMPATIBLE Mg-P COATING ON SURFACE OF ZINC-BASED BIOMEDICAL MATERIAL, AND PREPARATION METHOD AND USE THEREOF

Abstract

A biocompatible Mg—P coating on the surface of a zinc-based biomedical material, and a preparation method and use thereof are disclosed. In the method, zinc and a zinc alloy are first subjected to surface pretreatment and then soaked in a phosphate solution at a constant temperature to form the Mg—P coating through chemical liquid deposition (CLD). The control on the composition, thickness and surface morphology of the coating is realized by using the CLD method. The biocompatible Mg—P coating has a thickness of 0.5 μm to 50 μm, is dense and uniform, and comprises a main component of zinc-magnesium-phosphate and a small amount of zinc phosphate.

Claims

1. A method for preparing a biocompatible Mg—P coating on a surface of a zinc-based biomedical material, comprising the following steps: S1. performing a pretreatment on the surface of the zinc-based biomedical material to obtain a pretreated medical zinc alloy, wherein, the pretreatment comprises a polishing, an ultrasonic cleaning, and an ultraviolet (UV)-ozone cleaning; and S2. soaking the pretreated medical zinc alloy obtained in step S1 in a slightly-acidic magnesium salt- and phosphate-containing solution at a constant temperature, and conducting chemical liquid deposition (CLD) to obtain the biocompatible Mg—P coating.

2. The method for preparing the biocompatible Mg—P coating according to claim 1, wherein, in step S2, a magnesium salt of the slightly-acidic magnesium salt- and phosphate-containing solution is at least one selected from the group consisting of magnesium sulfate, magnesium nitrate, and magnesium phosphate, and a phosphate of the slightly-acidic magnesium salt- and phosphate-containing solution is at least one selected from the group consisting of sodium phosphate, disodium phosphate (DSP), monosodium phosphate (MSP), potassium phosphate, dipotassium phosphate (DKP), and monopotassium phosphate (MKP).

3. The method for preparing the biocompatible Mg—P coating according to claim 1, wherein the slightly-acidic magnesium salt- and phosphate-containing solution in step S2 further comprises a solubilizing salt; and the solubilizing salt comprises ethylene diamine tetraacetic acid (EDTA).

4. The method for preparing the biocompatible Mg—P coating according to claim 1, wherein the magnesium salt has a concentration of 0.1 mol/L to 1 mol/L; the phosphate has a concentration of 0.15 mol/L to 1.5 mol/L; and the magnesium salt and the phosphate have a molar ratio of 0.5:5.

5. The method for preparing the biocompatible Mg—P coating according to claim 1, wherein, in step S2, the soaking is conducted at 10° C. to 80° C. for 0.5 h to 24 h, and the slightly-acidic magnesium salt- and phosphate-containing solution has a pH of 4.0 to 6.2.

6. The method for preparing the biocompatible Mg—P coating according to claim 1, wherein the ultrasonic cleaning in step S1 comprises the ultrasonic cleaning successively with absolute ethanol, acetone, and absolute ethanol.

7. The method for preparing the biocompatible Mg—P coating according to claim 1, wherein the zinc-based biomedical material is one selected from the group consisting of pure Zn, Zn—Cu binary alloy, Zn—Mg binary alloy, Zn—Sr binary alloy, Zn—Mn binary alloy, Zn—Li binary alloy, Zn—Ag binary alloy, Zn—Fe binary alloy, Zn—Re binary alloy, and a multi-element zinc alloy.

8. A biocompatible Mg—P coating on the surface of the zinc-based biomedical material prepared by the method according to claim 1, wherein the biocompatible Mg—P coating has a thickness of 0.5 μm to 50 μm, the biocompatible Mg—P coating is dense and uniform, and the biocompatible Mg—P coating comprises a main component of zinc-magnesium-phosphate and a predetermined amount of zinc phosphate.

9. The biocompatible Mg—P coating according to claim 8, wherein an outer surface of the biocompatible Mg—P coating further comprises submicro-sized to micro-sized magnesium hydrogen phosphate crystal grains.

10. A method of using a degradable zinc-based biomedical material with the biocompatible Mg—P coating according to claim 8 in a preparation of a biodegradable and absorbable medical device, wherein the biodegradable and absorbable medical device comprises a tissue engineering scaffold, a cardiovascular stent, a medical catheter, and an intraosseous implant device.

11. The method for preparing the biocompatible Mg—P coating according to claim 2, wherein the magnesium salt has a concentration of 0.1 mol/L to 1 mol/L; the phosphate has a concentration of 0.15 mol/L to 1.5 mol/L; and the magnesium salt and the phosphate have a molar ratio of 0.5:5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Other features, objectives, and advantages of the present invention will become more apparent by reading the detailed description of non-limiting examples with reference to the following accompanying drawings.

[0037] FIG. 1 is a scanning electron microscopy (SEM) image of the biocompatible Mg—P coating on the surface of a zinc alloy prepared in Example 1, with an enlarged image at the upper right corner. It can be seen from the figure that the surface of the coating has a micro-sized cluster-like morphology combined with a nano-sized rod-like structure and does not include micro-sized magnesium hydrogen phosphate particles;

[0038] FIG. 2 shows an X-ray diffraction (XRD) pattern of the biocompatible Mg—P coating on the surface of a zinc alloy prepared in example 1, which verifies the main components of the coating;

[0039] FIG. 3 is an SEM image of the biocompatible Mg—P coating on the surface of pure zinc prepared in Example 6, with an enlarged image at the upper right corner. It can be seen from the figure that the surface of the coating has a micro-sized cluster-like morphology combined with a nano-sized rod-like structure and includes micro-sized magnesium hydrogen phosphate particles;

[0040] FIG. 4 shows an XRD pattern of the biocompatible Mg—P coating on the surface of pure zinc prepared in example 6, which verifies the main components of the coating;

[0041] FIG. 5 shows the release curves of zinc and magnesium ions of the pure zinc with the biocompatible Mg—P coating prepared in Example 6 and the uncoated bare pure zinc in a cell culture medium. It can be seen that, within one week, the pure zinc with the biocompatible Mg—P coating prepared in Example 6 releases zinc ions at a significantly-reduced amount during degradation and can release an appropriate amount of magnesium ions at the same time, which is beneficial to improving the biocompatibility and biological activity of a zinc-based material surface;

[0042] FIG. 6A is the fluorescence microscopy image of live cells of osteoblasts adhered to the biocompatible Mg—P coating on the surface of the zinc alloy prepared in Example 1;

[0043] FIG. 6B is the fluorescence microscopy image of dead cells of osteoblasts adhered to the biocompatible Mg—P coating on the surface of the zinc alloy prepared in Example 1;

[0044] FIG. 6C is the fluorescence microscopy image of live cells on the bare zinc alloy in the control group;

[0045] FIG. 6D is the fluorescence microscopy image of dead cells of the bare zinc alloy in the control group; it can be seen that the cells adhered to the modified Mg—P coating show a significantly-improved survival rate; and

[0046] FIG. 7 is an SEM image of the biocompatible Mg—P coating on the surface of a zinc alloy prepared in Comparative Example 1, with an enlarged image at the upper right corner. It can be seen that the coating is not uniform and cannot completely cover the surface of the zinc substrate, and the bare part of the zinc substrate is corroded.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The present invention is described in detail below with reference to specific examples. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those of ordinary skill in the art can further make several variations and improvements without departing from the idea of the present invention. These all fall within the protection scope of the present invention.

Example 1

[0048] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. Specific steps were as follows:

[0049] 4) The extruded Zn-3 wt % Cu alloy was made into a Φ10×3 mm sample, polished successively with 320# and 1,200# waterproof abrasive papers, then subjected to ultrasonic cleaning for 10 min successively with absolute ethanol, acetone, and absolute ethanol, and blow-dried, and then both sides of the sample were each treated for 10 min with a UV-ozone cleaner.

[0050] 5) A phosphate reaction solution was prepared as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.2 mol/L and 0.3 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0051] 6) The treated Zn-3Cu alloy sample was statically soaked in the above phosphate reaction solution for 6 h at room temperature (25° C.).

[0052] As shown in the SEM image (as shown in FIG. 1), the surface of the coating had a micro-sized cluster-like morphology combined with a nano-sized rod-like structure and did not include micro-sized magnesium hydrogen phosphate particles. It was also observed that the Mg—P coating had a thickness of about 10 μm, a Mg/Zn/P atomic ratio of about 1:2:2, and a bonding force as high as 10 MPa with the Zn-3Cu alloy matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 10% of that of a bare Zn-3Cu alloy, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the zinc alloy surface. An XRD pattern of the biocompatible Mg—P coating on the surface of the zinc alloy prepared in this example is shown in FIG. 2. Fluorescence microscopy images for the live/dead staining of osteoblasts adhered to the biocompatible Mg—P coating on the surface of the zinc alloy are shown in FIGS. 6A-B, and compared with fluorescence microscopy images for the live/dead staining of cells adhered to the bare zinc alloy in the control group (as shown in FIGS. 6C-D), it can be seen that adhered cells have a significantly-improved survival rate after modification with the Mg—P coating. The coating process in this example is suitable for the preparation of a surface coating for vascular stents manufactured from the Zn-3Cu alloy.

Example 2

[0053] A biocompatible Mg—P coating was prepared on the surface of a Zn—Mg alloy porous bone tissue engineering scaffold for tissue engineering. Specific steps were as follows:

[0054] 4) The Zn—Mg alloy porous bone tissue engineering scaffold for tissue engineering was made into a Φ10×3 mm sample, then the porous surface was polished by electrolytic polishing, and a resulting sample was subjected to ultrasonic cleaning for 10 min successively with absolute ethanol, acetone, and absolute ethanol, blow-dried, and then treated for 10 min with a UV-ozone cleaner.

[0055] 5) A phosphate reaction solution was prepared as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.2 mol/L and 0.3 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 5.0 with a 1 mol/L NaOH solution.

[0056] 6) The treated Zn—Mg alloy porous bone tissue engineering scaffold sample was put in the above phosphate reaction solution, and static soaking was conducted for 12 h in a water bath at a constant temperature (50° C.).

[0057] It was observed from SEM that the Mg—P coating had a total thickness of about 30 μm and a Mg/Zn/P atomic ratio of about 1:2:2; the micro-sized crystal grains on the coating surface had a Mg/P atomic ratio of about 1:1 and basically included no Zn atoms; and there was a bonding force as high as 8 MPa between the coating and the Zn—Mg alloy porous bone tissue engineering scaffold matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 11% of that of a bare Zn—Mg alloy porous bone tissue engineering scaffold, and could release an appropriate amount of magnesium ions at the same time. The MC3T3-E1 osteoblasts were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading osteoblasts were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of osteoblasts and significantly improves the cell compatibility of the zinc alloy tissue engineering scaffold surface.

Example 3

[0058] A biocompatible Mg—P coating was prepared on the surface of a cardiovascular stent manufactured from a Zn—Mn alloy. Specific steps were as follows:

[0059] 4) The Zn—Mn alloy was made into a Φ3×15 mm sample, then the surface was polished by electrolytic polishing, and a resulting sample was subjected to ultrasonic cleaning for 10 min successively with absolute ethanol, acetone, and absolute ethanol, blow-dried, and then treated for 10 min with a UV-ozone cleaner.

[0060] 5) A phosphate reaction solution was prepared as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.3 mol/L and 0.45 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0061] 6) The treated Zn—Mn alloy cardiovascular stent sample was statically soaked in the above phosphate reaction solution for 1 h at room temperature (25° C.).

[0062] It was observed from SEM that the Mg—P coating had a thickness of about 1.5 μm and a Mg/Zn/P atomic ratio of about 1:2:2; and there was a bonding force as high as 10 MPa between the coating and the Zn—Mn alloy cardiovascular stent matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 12% of that of a bare Zn—Mn alloy stent, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the zinc alloy stent surface.

Example 4

[0063] A biocompatible Mg—P coating was prepared on the surface of a Zn—Cu—Fe alloy bone nail. Specific steps were as follows:

[0064] 4) The Zn—Cu—Fe alloy was made into a Φ4×10 mm bone nail sample, then the surface was polished by sand blasting, and a resulting sample was subjected to ultrasonic cleaning for 10 min successively with absolute ethanol, acetone, and absolute ethanol, blow-dried, and then treated for 10 min with a UV-ozone cleaner.

[0065] 5) A phosphate reaction solution was prepared as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.2 mol/L and 0.3 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 6.0 with a 1 mol/L NaOH solution.

[0066] 6) The treated Zn—Cu—Fe alloy sample was put in the above phosphate reaction solution, and static soaking was conducted for 2.5 h in a water bath at a constant temperature (35° C.).

[0067] It was observed from SEM that the Mg—P coating had a total thickness of about 15 μm and a Mg/Zn/P atomic ratio of about 1:2:2; the micro-sized crystal grains on the coating surface had a Mg/P atomic ratio of about 1:1 and basically included no Zn atoms; and there was a bonding force as high as 8 MPa between the coating and the Zn—Cu—Fe alloy matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 11% of that of a bare Zn—Cu—Fe alloy, and could release an appropriate amount of magnesium ions at the same time. The MC3T3-E1 osteoblasts were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading osteoblasts were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of osteoblasts and significantly improves the cell compatibility of the zinc alloy bone nail surface.

Example 5

[0068] A biocompatible Mg—P coating was prepared on the surface of an intramedullary pin sample (Φ2×100 mm) manufactured from an extruded Zn-1Ag (Zn—Ag) alloy. Specific steps were as follows:

[0069] 4) The extruded Zn-1Ag alloy was made into a 02×100 mm sample, polished successively with 320# and 1,200# waterproof abrasive papers, then subjected to ultrasonic cleaning for 10 min successively with absolute ethanol, acetone, and absolute ethanol, blow-dried, and then treated for 10 min with a UV-ozone cleaner.

[0070] 5) A phosphate reaction solution was prepared as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.3 mol/L and 0.45 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.9 with a 1 mol/L NaOH solution.

[0071] 6) The treated Zn-1Ag alloy sample was put in the above phosphate reaction solution, and static soaking was conducted for 6 h in a water bath at a constant temperature (50° C.).

[0072] It was observed from SEM that the Mg—P coating had a total thickness of about 8 μm and a Mg/Zn/P atomic ratio of about 1:2:2; the micro-sized crystal grains on the coating surface had a Mg/P atomic ratio of about 1:1 and basically included no Zn atoms; and there was a bonding force as high as 8 MPa between the coating and the Zn-1Ag alloy matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 10% of that of a bare Zn-1Ag alloy, and could release an appropriate amount of magnesium ions at the same time. The MC3T3-E1 osteoblasts were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading osteoblasts were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of osteoblasts and significantly improves the cell compatibility of the zinc alloy intramedullary pin surface.

Example 6

[0073] A biocompatible Mg—P coating was prepared on the surface of a bone plate manufactured from pure zinc. Specific steps were as follows:

[0074] 4) The pure zinc was made into a Φ10×3 mm sample, polished successively with 320# and 1,200# waterproof abrasive papers, then subjected to ultrasonic cleaning for 10 min successively with absolute ethanol, acetone, and absolute ethanol, and blow-dried, and then both sides of the sample were each treated for 10 min with a UV-ozone cleaner.

[0075] 5) A phosphate reaction solution was prepared as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.2 mol/L and 0.3 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0076] 6) The treated pure zinc sample was statically soaked in the above phosphate reaction solution for 20 h at room temperature (25° C.).

[0077] It was observed from SEM (FIG. 3) that the surface of the coating had a micro-sized cluster-like morphology combined with a nano-sized rod-like structure and included micro-sized magnesium hydrogen phosphate particles. The Mg—P coating had a thickness of about 45 μm and a Mg/Zn/P atomic ratio of about 1:2:2; and there was a bonding force as high as 10 MPa between the coating and the pure zinc matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 10% of that of bare pure zinc, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the pure zinc bone plate surface. An XRD pattern of the biocompatible Mg—P coating on the surface of pure zinc prepared in this example is shown in FIG. 4. The release curves of zinc and magnesium ions of the pure zinc with the biocompatible Mg—P coating prepared in this example in a cell culture medium are shown in FIG. 5. It can be seen that, within one week, compared with bare pure zinc without coating, the pure zinc with the biocompatible Mg—P coating prepared in Example 6 releases zinc ions at a significantly-reduced amount during degradation and can release an appropriate amount of magnesium ions at the same time, which is beneficial to improving the biocompatibility and biological activity of a zinc-based material surface.

Example 7

[0078] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. The specific steps in this example were basically the same as Example 1 except that:

[0079] In step 2), a phosphate reaction solution in this example was prepared specifically as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 0.5:1 (a ratio of the amounts of the substances, 0.1 mol/L and 0.2 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 6.2 with a 1 mol/L NaOH solution.

[0080] In step 3), the treated Zn-3Cu alloy sample was statically soaked in the above phosphate reaction solution for 24 h at 10° C. in this example.

[0081] It was observed from SEM that the Mg—P coating had a thickness of about 20 μm and a Mg/Zn/P atomic ratio of about 1:2:2; and there was a bonding force as high as 8 MPa between the coating and the Zn-3Cu alloy matrix. The Mg—P coating prepared in this example, after soaked in a DMEM medium for one week, showed a zinc release rate reduced to 12% of that of a bare Zn-3Cu alloy, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the zinc alloy surface.

Example 8

[0082] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. The specific steps in this example were basically the same as Example 1 except that:

[0083] In step 2), a phosphate reaction solution in this example was prepared specifically as follows: MgSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 5:1 (a ratio of the amounts of the substances, 1 mol/L and 0.2 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0084] In step 3), the treated Zn-3Cu alloy sample was statically soaked in the above phosphate reaction solution for 0.5 h at 80° C. in this example.

[0085] It was observed from SEM that the Mg—P coating had a thickness of about 40 μm and a Mg/Zn/P atomic ratio of about 1:2:2. The micro-sized crystal grains on the coating surface had a Mg/P atomic ratio of about 1:1 and basically included no Zn atoms; and there was a bonding force as high as 8 MPa between the coating and the Zn-3Cu alloy matrix. The Mg—P coating prepared in this example, after soaked in a DMEM medium for one week, showed a zinc release rate reduced to 11% of that of a bare Zn-3Cu alloy, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the zinc alloy surface.

Example 9

[0086] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. The specific steps in this example were basically the same as Example 1 except that:

[0087] In step 2), a phosphate reaction solution in this example was prepared specifically as follows: Mg(NO.sub.3).sub.2 and Na.sub.2HPO.sub.4 were taken at a ratio of 7:3 (a ratio of the amounts of the substances, 0.35 mol/L and 0.15 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0088] It was observed from SEM that the Mg—P coating had a thickness of about 20 μm and a Mg/Zn/P atomic ratio of about 1:2:2; the micro-sized crystal grains on the coating surface had a Mg/P atomic ratio of about 1:1 and basically included no Zn atoms; and there was a bonding force as high as 8 MPa between the coating and the Zn-3Cu alloy matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 12% of that of a bare Zn-3Cu alloy, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the zinc alloy surface.

Example 10

[0089] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. The specific steps in this example were basically the same as Example 1 except that:

[0090] In step 2), a phosphate reaction solution in this example was prepared specifically as follows: Mg.sub.3(PO.sub.4).sub.2 and KH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.2 mol/L and 0.3 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0091] It was observed from SEM that the Mg—P coating had a thickness of about 10 μm and a Mg/Zn/P atomic ratio of about 1:2:2; and there was a bonding force as high as 10 MPa between the coating and the Zn-3Cu alloy matrix. The Mg—P coating prepared in this example, after soaked in a α-MEM medium for one week, showed a zinc release rate reduced to 10% of that of a bare Zn-3Cu alloy, and could release an appropriate amount of magnesium ions at the same time. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of spreading ECs were adhered to the surface of the Mg—P coating and the coating exhibited cytotoxicity reduced from level 2 to level 0, indicating that the Mg—P coating can promote the spreading, adhesion, and proliferation of ECs and significantly improves the cell compatibility of the zinc alloy surface.

Comparative Example 1

[0092] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. The specific steps in this example were basically the same as Example 1 except that:

[0093] In step 2), a phosphate reaction solution in this example was prepared specifically as follows: KH.sub.2PO.sub.4 was taken (0.5 mol/L) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0094] It was observed from SEM (as shown in FIG. 7) that the surface of the substrate was covered with a non-uniform and non-dense coating at a thickness of about 20 μm; the uncovered surface was corroded; a Zn/P atomic ratio was about 3:2 and there was no Mg atoms; and there was a bonding force of 6 MPa between the coating and the Zn-3Cu alloy matrix. The coating prepared in this comparative example, after soaked in a α-MEM medium for one week, showed a zinc release rate basically the same as that of a bare Zn-3Cu alloy. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of dead ECs were adhered to the coating surface and the coating exhibited cytotoxicity still at levels 1 to 2, without significant improvement.

Comparative Example 2

[0095] A biocompatible Mg—P coating was prepared on the surface of an extruded Zn-3 wt % Cu (Zn—Cu) alloy material. The specific steps in this example were basically the same as Example 1 except that:

[0096] In step 2), a phosphate reaction solution in this example was prepared specifically as follows: ZnSO.sub.4 and NaH.sub.2PO.sub.4 were taken at a ratio of 1:1.5 (a ratio of the amounts of the substances, 0.2 mol/L and 0.3 mol/L, respectively) and dissolved with deionized water, and a pH was adjusted to 4.0 with a 1 mol/L NaOH solution.

[0097] It was observed from SEM that the surface of the substrate was covered with a non-uniform and non-dense coating at a thickness of about 25 μm. The uncovered surface was corroded; a Zn/P atomic ratio was about 3:2 and there was no Mg atoms; and there was a bonding force of 6 MPa between the coating and the Zn-3Cu alloy matrix. The coating prepared in this comparative example, after soaked in a α-MEM medium for one week, showed a zinc release rate basically the same as that of a bare Zn-3Cu alloy. The EA. Hy926 ECs were used to evaluate the biocompatibility of the Mg—P coating prepared in this example, and results showed that a large number of dead ECs were adhered to the coating surface and the coating exhibited cytotoxicity still at levels 1 to 2, without significant improvement.

[0098] There are many ways to specifically apply the present invention, and the above are merely preferred implementations of the present invention. It should be noted that the foregoing examples are provided only for illustrating the present invention and are not intended to limit the protection scope of the present invention. For a person of ordinary skill in the art, several improvements may further be made without departing from the principle of the present invention, and these improvements should also be considered as falling within the protection scope of the present invention.