Magnesium-based bone implant material surface modification composite coating and preparation method thereof

Abstract

The invention discloses a magnesium-based bone implant material surface modified composite coating and a preparation method thereof, and relates to the technical field of biomedical materials. The modified composite coating comprises a micro-arc oxidation ceramic layer, a bone healing promoting functional layer and an antibacterial functional layer, wherein the micro-arc oxidation ceramic layer covers the surface of the magnesium-based bone implant material; the bone healing promoting functional layer and the antibacterial functional layer are sequentially loaded on the micro-arc oxidation ceramic layer; the bone healing promoting functional layer comprises a sustained-release material and icariin wrapped in the sustained-release material; the antibacterial functional layer comprises antibacterial peptide, and the antibacterial peptide is grafted on the bone healing promoting functional layer. The composite coating effectively regulates and controls release behaviors of bone healing promoting components and antibacterial components, and realizes dynamic regulation of a microenvironment of a bone repair part; moreover, the magnesium-based bone implant material also has excellent biocompatibility, can provide a good cell basis for bone regeneration, and is beneficial to large-scale application of the magnesium-based bone implant material in bone wound healing.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, mainly to the field of bone implant materials technology, and specifically to a magnesium-based bone implant material surface-modified composite coating and its preparation method. Background Technology

[0002] Bone defects are a common clinical condition in orthopedics, with the number of patients worldwide increasing due to factors such as population aging, traffic accidents, and sports injuries, making the demand for efficient bone repair materials increasingly urgent. Among various bone implant materials, biodegradable magnesium alloys have become a hot topic in current research and clinical applications due to their advantages such as elastic modulus close to that of human bone, good biocompatibility, and gradual degradation in vivo. However, the degradation rate of magnesium alloys in the complex physiological environment of the body is too rapid, making it difficult to maintain sufficient mechanical strength during the critical period of bone healing, thus limiting their long-term application effectiveness. To overcome this deficiency, surface modification technology has been widely used in magnesium-based bone implant materials, aiming to delay the degradation of the magnesium matrix and endow it with specific biological functions by constructing functional coatings. At the same time, the ideal bone repair process has a clear temporal characteristic: early prevention of bacterial infection is necessary to create conditions for mid-to-late-stage bone regeneration; while mid-to-late-stage bone repair requires continuous promotion of osteogenic differentiation to achieve complete reconstruction of bone structure. Therefore, developing surface coatings with both early antibacterial and mid-to-late-stage osteogenic induction functions is of great significance for improving bone repair efficacy.

[0003] Currently, among the existing surface modification technologies for magnesium-based bone implants, there is a technique that constructs a functional gradient composite coating on the surface of magnesium alloys consisting of a "micro-arc oxidation (MAO) ceramic layer + a pure calcium phosphate transition layer and a calcium phosphate doped with zinc oxide". For example, patent publication number CN117888167 discloses a functional gradient coating for magnesium and magnesium alloy bone implants, its preparation method, and its uses. This patented technology first constructs a porous substrate that facilitates the bonding of the calcium phosphate coating through micro-arc oxidation, and then prepares a pure calcium phosphate transition layer and a calcium phosphate functional gradient composite coating doped with zinc oxide through two-step electrodeposition. Through the above functional gradient design, pure magnesium or magnesium alloys can be endowed with excellent antibacterial properties and bone healing properties, and the controllable degradation of magnesium and magnesium alloys can be achieved. It has broad application prospects in the field of surface coating preparation and surface modification materials for magnesium and magnesium alloy bone implants. However, the above technology still has significant drawbacks: First, it utilizes the antibacterial and bone-healing properties of traditional zinc oxide to achieve both antibacterial and healing-promoting functions, which has the problems of limited antibacterial spectrum and potential cytotoxicity. Second, the coating only loads a single drug (zinc oxide), and its dual functions of antibacterial and bone-healing do not match the static functional design in the bone repair process and the complex requirements of "anti-infection first, then bone-promoting" in the dynamic process of bone healing, and cannot achieve efficient synergistic cooperation in the bone healing process.

[0004] Therefore, developing a magnesium-based bone implant material with a modified composite coating to address the problems of early postoperative infection and slow bone healing in the middle and late stages of bone tissue implantation is more conducive to promoting vascularization and bone healing during the bone repair process, and also plays an important role in the large-scale promotion and application of magnesium-based bone implant materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing magnesium-based bone implant material surface modification technology, which is inconsistent with the static functional design in the bone repair process and the complex requirements of "anti-infection first, then bone promotion" in the dynamic process of bone healing, and cannot achieve efficient synergy in the bone healing process. The invention proposes a magnesium-based bone implant material surface modification composite coating and its preparation method.

[0006] To achieve the above-mentioned objectives, the present invention also proposes a modified composite coating for the surface of magnesium-based bone implant materials. The modified composite coating includes a micro-arc oxidation ceramic layer (PEO) covering the surface of the magnesium-based bone implant material and a bone healing promoting functional layer and an antibacterial functional layer sequentially loaded on the micro-arc oxidation ceramic layer. The bone healing promoting functional layer includes a sustained-release material and icariin (ICA) encapsulated in the sustained-release material. The antimicrobial functional layer includes antimicrobial peptides (AMPs); the antimicrobial peptides are grafted onto the bone healing promoting functional layer.

[0007] This invention discloses a modified composite coating on the surface of a magnesium-based bone implant material. It not only utilizes the encapsulation effect of sustained-release materials, the physical grafting of dopamine and polyphenols, and the adjustment of the functional layer structure sequence to effectively regulate the release behavior of bone-healing components (icariin) and antibacterial components (antimicrobial peptides), meeting the complex requirement of "anti-infection first, then bone-promoting" in the dynamic process of bone healing, but also achieves dynamic regulation of the microenvironment at the bone repair site. This leads to the efficient activation of intracellular antibacterial and osteogenic pathways and proteins, more effectively synergistically promoting angiogenesis and bone regeneration, and significantly improving the promoting effect on bone healing. Furthermore, through targeted screening of relevant material types, the modified composite coating maintains excellent biocompatibility, effectively maintaining the activity of bone marrow mesenchymal stem cells (BMSCs), providing a good cellular basis for bone regeneration, and facilitating the large-scale application of magnesium-based bone implant materials in bone trauma healing.

[0008] Preferably, the magnesium-based implant material includes one or more of AZ31 magnesium alloy, WE43 magnesium alloy, Mg-Mn-Zn magnesium alloy, and JDBM magnesium alloy.

[0009] Preferably, in the modified composite coating, the thickness of the micro-arc oxidation ceramic layer is 5-10 μm; preferably, the thickness of the bone healing promoting functional layer is 30-40 μm; preferably, the thickness of the antibacterial functional layer is 0.2-0.6 μm.

[0010] Preferably, the content of icariin in the bone healing promoting functional layer is 2-6 mg / cm³. 2 .

[0011] Preferably, the content of antimicrobial peptides in the antimicrobial functional layer is 2-8 mg / cm³. 2 .

[0012] Under preferred conditions, the modified composite coating exhibits superior antibacterial and bone-healing effects.

[0013] Preferably, the sustained-release material is a biodegradable medical polymer material, such as polylactic acid (PLA) or polytrimethylene carbonate (PTMC).

[0014] Preferably, the antimicrobial peptide is grafted onto the bone healing functional layer via dopamine (DA) and polyphenol (EGCG); the preferred grafting material has the advantages of good grafting effect, no impact on biocompatibility, and no impact on the efficacy and release effect of the antimicrobial peptide.

[0015] To achieve the above-mentioned objectives, this invention further proposes a method for preparing a modified composite coating on the surface of a magnesium-based bone implant material, comprising the following steps: S1: The magnesium-based bone implant material is subjected to micro-arc oxidation treatment to obtain a micro-arc oxidized ceramic layer covering the surface of the magnesium-based bone implant material; S2: A mixture of icariin was coated onto the surface of a magnesium-based bone implant material covered with a micro-arc oxidized ceramic layer and then dried to obtain a micro-arc oxidized ceramic layer and a bone healing promoting functional layer sequentially covering the surface of the magnesium-based bone implant material. S3: The magnesium-based bone implant material covered with a micro-arc oxidation ceramic layer and a bone healing promoting functional layer is immersed and deposited in a solution containing icariin, and then surface grafted with an antimicrobial peptide solution to obtain a modified composite coating covering the surface of the magnesium-based bone implant material with a micro-arc oxidation ceramic layer, a bone healing promoting functional layer and an antimicrobial functional layer in sequence.

[0016] This invention discloses a method for preparing a modified composite coating on the surface of magnesium-based bone implant materials. First, a micro-arc oxidation ceramic layer is prepared as a carrier using a micro-arc oxidation process. Then, a bone-healing functional layer (containing icariin) and an antibacterial functional layer (containing antimicrobial peptides) are prepared sequentially. This yields a modified composite coating that meets the complex requirements of "anti-infection first, then bone-healing" in the dynamic process of bone healing. The preparation method of this modified composite coating has mild preparation conditions, good controllability, and stable quality. It can stably prepare a composite coating that can sequentially release corresponding effective components, making it suitable for large-scale production of modified composite coatings on the surface of magnesium-based bone implant materials.

[0017] Preferably, in step S1, before performing the micro-arc oxidation treatment, a pretreatment of the magnesium-based bone implant material is also included; the pretreatment can remove impurities and oxide layers on the surface of the magnesium-based bone implant material, improve its surface activity, and facilitate the formation of the micro-arc oxidation ceramic layer.

[0018] More preferably, the pretreatment method includes: polishing the magnesium-based bone implant material with water-based sandpaper, placing it in anhydrous ethanol solution, cleaning it at least twice with an ultrasonic cleaner, and drying it at 35-45°C.

[0019] Preferably, the micro-arc oxidation treatment method includes: using a magnesium-based bone implant material as the anode and a Ti-6Al-4V or graphite material as the cathode, and passing a micro-arc oxidation pulsed direct current through the micro-arc oxidation electrolyte.

[0020] More preferably, the micro-arc oxidation electrolyte is a mixed aqueous solution consisting of a phosphate, silicate, chlorate or borate solution with a concentration of 0.02-0.04 mol / mL and an alkaline solution with a concentration of 0.03-0.05 mol / mL.

[0021] More preferably, the power supply mode of the micro-arc oxidation pulsed DC power supply is constant current mode, with an operating voltage of 600V and a positive and negative current density of 3-10A / dm². 2 The frequency is 400-500Hz, the pulse width is 300μs, and the duty cycle is 30-50%.

[0022] More preferably, the micro-arc oxidation treatment takes 5-10 minutes and the temperature is 10-30°C.

[0023] In S2, preferably, the icariin mixed solution includes a solvent, icariin, and polytrimethylene carbonate; more preferably, the solvent is N,N-dimethylformamide (DMF) or chloroform, the concentration of icariin is 0.5-5.0 mg / mL (most preferably 1.5 mg / mL), and the concentration of polytrimethylene carbonate (PTMC) is 8.5-9.5 mg / mL; the preferred mixed solution composition enables better release of icariin during the bone repair period, thereby promoting bone healing.

[0024] Preferably, the drying process is carried out at a temperature of 55-65°C for 5-7 hours. These preferred drying conditions enable rapid drying and curing to form an icariin functional coating without causing denaturation of the icariin.

[0025] In S3, preferably, the concentration of dopamine in the solution containing dopamine and polyphenol is 0.8-2.2 mg / mL, and the concentration of polyphenol is 0.15-0.25 mg / mL.

[0026] More preferably, the soaking and deposition treatment is carried out sequentially using a first dopamine solution and a second dopamine solution containing polyphenols; the multi-stage soaking and deposition treatment can increase the grafting amount of antimicrobial peptides and enhance the antimicrobial effect.

[0027] More preferably, the first dopamine solution is a mixed solution of dopamine and Tris-HCl buffer, wherein the concentration of dopamine is 1.8-2.2 mg / mL; the second dopamine solution is a mixed solution of dopamine, polyphenol and Tris-HCl buffer, wherein the concentration of dopamine is 0.9-1.1 mg / mL and the concentration of polyphenol is 0.15-0.25 mg / mL.

[0028] Preferably, the soaking and sedimentation treatment is a static soaking treatment for 1.5-2.5 hours at room temperature.

[0029] Preferably, the antimicrobial peptide solution is a mixed solution of antimicrobial peptide and Tris-HCl buffer, wherein the concentration of the antimicrobial peptide is 0.5-5.0 mg / mL (most preferably 2.0 mg / mL).

[0030] Preferably, the surface grafting treatment is performed at a temperature of 3-5°C for 20-28 hours.

[0031] Preferably, the solute concentration in the Tris-HCl buffer solution is 0.01 mol / L and the pH value is 8.5.

[0032] The beneficial effects of the technical solution of this invention are as follows: 1. The magnesium-based bone implant material of this invention features a modified composite coating on its surface. By utilizing the encapsulation effect of sustained-release materials, the physical grafting of dopamine and polyphenols, and the adjustment of the functional layer structure sequence, the release behavior of bone-healing components (icariin) and antibacterial components (antimicrobial peptides) is effectively regulated. This satisfies the complex requirement of "anti-infection first, then bone-promoting" in the dynamic process of bone healing, and achieves dynamic regulation of the microenvironment at the bone repair site. This leads to the efficient activation of intracellular antibacterial and osteogenic pathways and proteins, more effectively promoting vascularization and bone regeneration, and significantly improving the effect on promoting bone healing.

[0033] 2. The magnesium-based bone implant material of this invention has a modified composite coating on its surface. Through targeted screening of relevant material types, the modified composite coating still has excellent biocompatibility, thereby effectively maintaining the activity of bone marrow mesenchymal stem cells (BMSCs) and providing a good cellular basis for bone regeneration.

[0034] 3. The preparation method of the magnesium-based bone implant material surface modified composite coating of the present invention has mild preparation conditions, good controllability, and stable quality. It can stably prepare a composite coating that can sequentially release the corresponding effective components, and is suitable for large-scale production of magnesium-based bone implant material surface modified composite coating. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the process of preparing a modified composite coating on the surface of AZ31 magnesium alloy sheet in Embodiment 1 of the present invention.

[0036] Figure 2 The image shows the detection results of the surface morphology and chemical elements of the composite coating in Example 1 of the present invention (where A is the SEM and EDS image of the composite coating; B is the cross-sectional SEM and EDS image of the composite coating; C is the XPS full spectrum image; D is the FITIR image; E is the XPS image and atomic ratio; F is the static water contact angle; mean ± standard deviation, n = 3).

[0037] Figure 3 This is a diagram showing the test results of the corrosion resistance of the composite coating in Example 1 of the present invention.

[0038] Figure 4 This is a diagram showing the ion release test results of the composite coating in Example 1 of the present invention.

[0039] Figure 5 This is a graph showing the test results of the drug release experiment of the composite coating (ICR) in Example 1 of the present invention.

[0040] Figure 6The figure shows the results of the osteogenic activity verification experiment of the composite coating in vitro stem cells in Example 1 of the present invention (where A and C are the cell activity of bone marrow mesenchymal stem cells; B and D are the cell activity of CCK-8 cells; E is cell phalloidin staining; F is ALP and alizarin red staining and quantitative results; G is cell qPCR; (mean ± standard deviation, n = 3).

[0041] Figure 7 The following figures show the results of the in vitro antibacterial verification experiment of the composite coating in Example 1 of the present invention (A and B are plate counts of Staphylococcus aureus and Escherichia coli after co-culturing for 6, 12, and 24 hours with different magnesium alloys; C is the bacterial viability and mortality of Staphylococcus aureus and Escherichia coli after co-culturing for 24 hours with different magnesium alloys; D and E are plate counts of Staphylococcus aureus and Escherichia coli after soaking in PBS for 3, 5, and 7 days with different magnesium alloys).

[0042] Figure 8 The following figures show the results of the in vivo antibacterial and osteogenic verification experiment of the composite coating in Example 1 of the present invention (A is the surgical infection image at 1 week post-operation; B is the Micro-CT staining image at 8 weeks; C is the H&E staining image at 8 weeks).

[0043] Figure 9 This is a verification result diagram of whether the composite coating in Example 1 of the present invention has systemic side effects (H&E staining diagram of heart, liver, spleen, lung, kidney and brain tissue sections 8 weeks after surgery). Detailed Implementation

[0044] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the embodiments described herein. Example 1

[0045] A modified composite coating was prepared on the surface of AZ31 magnesium alloy sheet (marked as AZ31). The specific method (process diagram is shown in the figure) is as follows. Figure 1 (As shown) includes: S1: The magnesium-based bone implant material (AZ31 magnesium alloy sheet) is pretreated (the AZ31 magnesium alloy sheet is polished with water-based sandpaper, placed in anhydrous ethanol solution, and cleaned in an ultrasonic cleaner (90%) for 5 min, cleaned three times, and dried at 40℃ for later use). Then, micro-arc oxidation treatment is performed (the pretreated AZ31 is used as the anode, Ti-6Al-4V (TC4) is used as the cathode, and a micro-arc oxidation electrolyte is prepared (the electrolyte is a mixed aqueous solution composed of a 0.03 mol / mL Na3PO4·12H2O solution and a 0.04 mol / mL KOH solution). The micro-arc oxidation pulsed DC power supply is connected, the power supply mode is constant current mode, and the main parameters are set as follows: working voltage 600V, positive and negative electrode current density 10A / dm³.2 (Frequency 500Hz, pulse width 300μs, duty cycle 30%, working time 6min, working temperature 20℃) to obtain magnesium-based bone implant material (AZ31-PEO sample, labeled MAO or PEO) with a surface covered by a micro-arc oxide ceramic layer. S2: A certain amount of polytrimethylene carbonate (PTMC) was added to N,N-dimethylformamide (DMF) (179.4 mg: 20 mL), and magnetically stirred at room temperature until the PTMC dissolved. An appropriate amount of icariin (ICA) was added to a test tube, resulting in an icariin mixed solution with a concentration of 1.5 mg / mL. Subsequently, icariin was coated onto the surface of a magnesium-based bone implant material covered with a micro-arc oxide ceramic layer (an AZ31-PEO sample was placed in the center of the mold hole, and icariin solution was dropped onto the sample surface, controlling the icariin content on the magnesium-based bone implant material surface to be approximately 2.5 mg / cm³). 2 The material was dried (placed in an oven at 60°C for 6 hours) to obtain a magnesium-based bone implant material (AZ31-PEO–I@P, labeled MAO-P@I or PEO-P@I) loaded with a micro-arc oxide ceramic layer and a bone healing-promoting functional layer. S3: Magnesium-based bone implant material coated with a micro-arc oxidation ceramic functional coating was sequentially treated with dopamine solution A (50 mg of dopamine (DA) dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a 2 mg / ml dopamine solution) and dopamine solution B (50 mg of dopamine (DA) dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a dopamine concentration of 2 mg / ml); 10 mg of polyphenol (epigallocatechin gallate, EGCG) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a dopamine concentration of 0.4 mg / ml. Solution A and solution B were then mixed to obtain a final concentration of 0.2 mg / mL EGCG and 1.0 mg / mL PDA. After soaking and deposition treatment with a 2 mg / mL dopamine second solution (after standing at room temperature for 2 h, the sample was taken out and washed with ultrapure water, then placed in ultrapure water for ultrasonic cleaning (40%) for 5 s, and dried for later use), the sample was then surface grafted with an antimicrobial peptide solution (60 mg of antimicrobial peptide (WRWRWR-NH2) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain an antimicrobial peptide solution with a concentration of 2 mg / mL). (The sample was placed in a petri dish, an appropriate amount of AMPs solution was added, and static physical grafting was performed at 4℃ for 24 h. The sample was taken out, placed in ultrapure water for shaking and washing twice, and then air-dried at room temperature). The resulting magnesium-based bone implant material (AZ31-PEO–ICA / PDA-AMPs; labeled MAO-P@IA or PEO-P@IA) was obtained with a micro-arc oxide ceramic layer, a bone healing promoting functional layer, and an antimicrobial functional layer sequentially coated on the surface.

[0046] In this modified composite coating, the average thickness of the micro-arc oxidation ceramic layer is approximately 5.1 μm; the average thickness of the bone healing promoting functional layer is approximately 38.6 μm; the average thickness of the antibacterial functional layer is approximately 0.4 μm; and the content of antimicrobial peptides in the antibacterial functional layer is approximately 7.5 mg / cm³. 2 . Example 2

[0047] A modified composite coating was prepared on the surface of WE43 magnesium alloy material. Specific methods included: S1: The magnesium-based bone implant material (WE43 magnesium alloy sheet) is pretreated (WE43 magnesium alloy sheet is polished with water-based sandpaper, placed in anhydrous ethanol solution and cleaned in an ultrasonic cleaner (90%) for 6 min, cleaned twice, and dried at 40℃ for later use). Then, micro-arc oxidation treatment is performed (pretreated WE43 is used as the anode and graphite as the cathode, and a micro-arc oxidation electrolyte is prepared (the electrolyte is 15 g / L Na2SiO3 and 30 g / L Na2B4O3).7、 A mixed aqueous solution of 30 g / L NaOH and 15 mL / L triethanolamine was used. The solution was connected to a micro-arc oxidation pulsed DC power supply in constant current mode. The main parameters were set as follows: operating voltage 600 V, positive and negative current density 3 A / dm³. 2 (Frequency 400Hz, pulse width 300μs, duty cycle 50%, working time 570s, working temperature 25℃), resulting in a magnesium-based bone implant material with a surface covered by a micro-arc oxide ceramic layer. S2: A certain amount of polytrimethylene carbonate (PTMC) was added to N,N-dimethylformamide (DMF) to obtain 9.0 mg / mL PTMC. The mixture was magnetically stirred at room temperature until the PTMC dissolved. An appropriate amount of icariin (ICA) was added to a test tube, resulting in an icariin mixed solution with a concentration of 1.2 mg / mL. Subsequently, the icariin mixed solution was coated onto the surface of a magnesium-based bone implant material covered with a micro-arc oxide ceramic layer, controlling the icariin content on the surface of the magnesium-based bone implant material to be approximately 3.5 mg / cm³. 2 The material was dried (placed in an oven at 60°C for 9 hours) to obtain a magnesium-based bone implant material loaded with a micro-arc oxide ceramic layer and a bone healing-promoting functional layer. S3: Magnesium-based bone implant material coated with a micro-arc oxidation ceramic functional coating was immersed and deposited in a solution containing dopamine and polyphenols (0.02 mg / mL epigallocatechin gallate, EGCG; 2 mg / mL dopamine; Tris-HCl buffer (0.01 M, pH 8.5)). After standing at room temperature for 2 hours, the sample was removed, washed with ultrapure water, removed, and ultrasonically cleaned in ultrapure water (40%) for 5 seconds, then dried for later use. Next, an antimicrobial peptide solution was used (60 mg of antimicrobial peptide (WRWRWR-NH2) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a concentration of 2... The sample was treated with an antimicrobial peptide solution of mg / mL for surface grafting (the sample was placed in a petri dish, an appropriate amount of AMPs solution was added, and static physical grafting was performed at 4℃ for 24 hours. The sample was then removed, placed in ultrapure water and shaken twice, and air-dried at room temperature) to obtain a magnesium-based bone implant material with a micro-arc oxide ceramic layer, a bone healing promoting functional layer and an antimicrobial functional layer sequentially coated on the surface.

[0048] In this modified composite coating, the average thickness of the micro-arc oxidation ceramic layer is approximately 6.2 μm; the average thickness of the bone healing promoting functional layer is approximately 35.2 μm; the average thickness of the antibacterial functional layer is approximately 0.5 μm; and the content of antimicrobial peptides in the antibacterial functional layer is approximately 7.2 mg / cm³. 2 . Example 3

[0049] The method for preparing a modified composite coating on the surface of Mg-Mn-Zn magnesium alloy materials includes: S1: The magnesium-based bone implant material (Mg-Mn-Zn magnesium alloy sheet) is pretreated (the Mg-Mn-Zn magnesium alloy sheet is polished with water-based sandpaper, placed in anhydrous ethanol solution, and cleaned in an ultrasonic cleaner (90%) for 4 minutes, repeated 3 times, and dried at 45℃ for later use). Then, micro-arc oxidation treatment is performed (the pretreated Mg-Mn-Zn is used as the anode, graphite as the cathode, and a micro-arc oxidation electrolyte (a mixed aqueous solution of 40 g / L NaOH and 4 g / L KF) is prepared). The micro-arc oxidation pulsed DC power supply is connected in constant current mode. The main parameters are set as follows: working voltage 600V, positive and negative electrode current density 3A / dm³. 2 (Frequency 500Hz, pulse width 300μs, duty cycle 3%, working time 3min, working temperature 20℃), resulting in a magnesium-based bone implant material with a surface covered by a micro-arc oxide ceramic layer; S2: Prepare an icariin solution (dissolve icariin and polylactic acid separately in chloroform solvent, and stir in a sealed container at room temperature until dissolved to obtain a 2 mg / mL icariin mixed solution; the polylactic acid concentration is 10%). Add the icariin mixed solution dropwise to the surface of the magnesium-based bone implant material coated with a micro-arc oxide ceramic layer, controlling the icariin content on the surface of the magnesium-based bone implant material to be approximately 4.5 mg / mL. 2 The material was then dried (placed in an oven at 40°C for 24 hours) to obtain a magnesium-based bone implant material loaded with a micro-arc oxide ceramic layer and a bone healing-promoting functional layer. S3: Magnesium-based bone implant material coated with a micro-arc oxidation ceramic functional coating was immersed and deposited in a solution containing dopamine and polyphenols (0.02 mg / mL epigallocatechin gallate, EGCG; 1 mg / mL dopamine; Tris-HCl buffer (0.01 M, pH 8.5)). After standing at room temperature for 2 hours, the sample was removed, washed with ultrapure water, removed, and ultrasonically cleaned in ultrapure water (40%) for 5 seconds, then dried for later use. Next, an antimicrobial peptide solution was used (60 mg of antimicrobial peptide (WRWRWR-NH2) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a concentration of 2.5%. The sample was treated with an antimicrobial peptide solution of mg / mL for surface grafting (the sample was placed in a petri dish, an appropriate amount of AMPs solution was added, and static physical grafting was performed at 4℃ for 24 hours. The sample was then removed, placed in ultrapure water and shaken twice, and air-dried at room temperature) to obtain a magnesium-based bone implant material with a micro-arc oxide ceramic layer, a bone healing promoting functional layer and an antimicrobial functional layer sequentially coated on the surface.

[0050] In this modified composite coating, the average thickness of the micro-arc oxidation ceramic layer is approximately 9.5 μm; the average thickness of the bone healing promoting functional layer is approximately 30.5 μm; the average thickness of the antibacterial functional layer is approximately 0.2 μm; and the content of antimicrobial peptides in the antibacterial functional layer is approximately 2.3 mg / cm³. 2 . Example 4

[0051] The method for preparing a modified composite coating on the surface of JDBM magnesium alloy material includes: S1: The magnesium-based bone implant material (JDBM magnesium alloy sheet) is pretreated (JDBM magnesium alloy sheet is polished with water-based sandpaper, placed in anhydrous ethanol solution and cleaned in an ultrasonic cleaner (90%) for 4 minutes, cleaned 3 times, and dried at 45℃ for later use). Then, micro-arc oxidation treatment is performed (pretreated JDBM is used as the anode and graphite as the cathode. A micro-arc oxidation electrolyte solution (a mixed aqueous solution composed of 0.03mol / L sodium phosphate, 0.04mol / L sodium hydroxide, and 0.04mol / L calcium fluoride) is prepared. The micro-arc oxidation pulsed DC power supply is connected. The power supply mode is constant current mode. The main parameters are set as follows: working voltage 600V, positive and negative electrode current density 10A / dm³. 2 (Frequency 400Hz, pulse width 300μs, duty cycle 30%, working time 6min, working temperature 20℃), resulting in a magnesium-based bone implant material with a surface covered by a micro-arc oxide ceramic layer; S2: Prepare a mixed solution of icariin (1.8 mg / mL icariin and 12 mg / mL polytrimethylene carbonate dissolved in chloroform). Place the sample on the surface of a magnesium-based bone implant material with a micro-arc oxide ceramic layer (in the center of the mold hole), coat the sample surface with the icariin solution, and control the icariin content on the magnesium-based bone implant material surface to be approximately 2.1 mg / cm³. 2 The material was then dried (placed in an oven at 60°C for 20 hours) to obtain a magnesium-based bone implant material loaded with a micro-arc oxide ceramic layer and a bone healing-promoting functional layer. S3: Magnesium-based bone implant material coated with a micro-arc oxidation ceramic functional coating was immersed and deposited in a solution containing dopamine and polyphenols (0.02 mg / mL epigallocatechin gallate, EGCG; 1 mg / mL dopamine; Tris-HCl buffer (0.01 M, pH 8.5)). After standing at room temperature for 2 hours, the sample was removed, washed with ultrapure water, removed, and ultrasonically cleaned in ultrapure water (40%) for 5 seconds, then dried for later use. Next, an antimicrobial peptide solution was used (60 mg of antimicrobial peptide (WRWRWR-NH2) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a concentration of 1.5%. The sample was treated with an antimicrobial peptide solution of mg / mL for surface grafting (the sample was placed in a petri dish, an appropriate amount of AMPs solution was added, and static physical grafting was performed at 4℃ for 24 hours. The sample was then removed, placed in ultrapure water and shaken twice, and air-dried at room temperature) to obtain a magnesium-based bone implant material with a micro-arc oxide ceramic layer, a bone healing promoting functional layer and an antimicrobial functional layer sequentially coated on the surface.

[0052] In this modified composite coating, the average thickness of the micro-arc oxidation ceramic layer is approximately 7.5 μm; the average thickness of the bone healing promoting functional layer is approximately 35.8 μm; the average thickness of the antibacterial functional layer is approximately 0.35 μm; and the content of antimicrobial peptides in the antibacterial functional layer is approximately 4.2 mg / cm³. 2 . Example 5

[0053] A modified composite coating was prepared on the surface of WE43 magnesium alloy material. Specific methods included: S1: The magnesium-based bone implant material (WE43 magnesium alloy sheet) is pretreated (WE43 magnesium alloy sheet is polished with water-based sandpaper, placed in anhydrous ethanol solution and cleaned in an ultrasonic cleaner (90%) for 4 minutes, cleaned 3 times, and dried at 45℃ for later use). Then, micro-arc oxidation treatment is performed (pretreated WE43 is used as the anode and TC4 is used as the cathode. A micro-arc oxidation electrolyte (a mixed aqueous solution of 0.03mol / L sodium phosphate and 0.04mol / L sodium hydroxide) is prepared. The micro-arc oxidation pulsed DC power supply is connected. The power supply mode is constant current mode. The main parameters are set as follows: working voltage 600V, positive and negative electrode current density 10A / dm³. 2 (Frequency 400Hz, pulse width 300μs, duty cycle 30%, working time 6min, working temperature 20℃), resulting in a magnesium-based bone implant material with a surface covered by a micro-arc oxide ceramic layer; S2: Prepare a mixed solution of icariin (2.0 mg / mL ICA and 11 mg / mL PTMC, dissolved in N,N-dimethylformamide solvent, stirred under sealed conditions at room temperature until dissolved). Coat the surface of the magnesium-based bone implant material covered with a micro-arc oxide ceramic layer (place the implant in the center of the mold hole, coat the sample surface with the icariin solution, and control the icariin content on the magnesium-based bone implant material surface to be approximately 8.0 mg / cm³). 2 The material was then dried (placed in an oven at 60°C for 10 hours) to obtain a magnesium-based bone implant material loaded with a micro-arc oxide ceramic layer and a bone healing-promoting functional layer. S3: Magnesium-based bone implant material coated with a micro-arc oxidation ceramic functional coating was sequentially treated with dopamine solution A (50 mg of dopamine (DA) dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a 2 mg / mL dopamine solution) and dopamine solution B (50 mg of dopamine (DA) dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a dopamine concentration of 2 mg / mL); 10 mg of polyphenol (epigallocatechin gallate, EGCG) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain a dopamine concentration of 0.4 mg / mL. Solution A and solution B were then mixed to obtain a final solution with an EGCG concentration of 0.2 mg / mL and a PDA concentration of 1.0 mg / mL. After soaking and deposition treatment with a 2 mg / mL dopamine second solution (after standing at room temperature for 2 h, the sample was taken out and washed with ultrapure water, then placed in ultrapure water for ultrasonic cleaning (40%) for 5 s, and dried for later use), the sample was then treated with an antimicrobial peptide solution (60 mg of antimicrobial peptide (WRWRWR-NH2) was dissolved in Tris-HCl buffer (0.01 M, pH 8.5) to obtain an antimicrobial peptide solution with a concentration of 2 mg / mL) for surface grafting treatment (the sample was placed in a petri dish, an appropriate amount of AMPs solution was added, and static physical grafting was performed at 4℃ for 24 h. The sample was taken out, placed in ultrapure water for shaking and washing twice, and then air-dried at room temperature) to obtain a magnesium-based bone implant material with a micro-arc oxide ceramic layer, a bone healing promoting functional layer, and an antimicrobial functional layer sequentially coated on the surface.

[0054] In this modified composite coating, the average thickness of the micro-arc oxidation ceramic layer is approximately 8.5 μm; the average thickness of the bone healing promoting functional layer is approximately 40 μm; the average thickness of the antibacterial functional layer is approximately 0.4 μm; and the content of antimicrobial peptides in the antibacterial functional layer is approximately 7.5 mg / cm³. 2 .

[0055] Experimental example: 1. Detection experiment of surface morphology and chemical elements of the composite coating in Example 1 The surface and cross-sectional morphology of the composite coating of icariin and antimicrobial peptide were observed by scanning electron microscopy (SEM, FEI Quanta FEG250, FEI, USA). The surface chemical elements of the composite layer were analyzed by energy-dispersive X-ray spectroscopy (EDS, EDAX Element, USA). Further analysis of the surface chemical elements of the composite layer was performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS, ThermoSCIENTIFIC ESCALAB 250Xi, USA). The results are shown below. Figure 2 As shown.

[0056] Figure 2 Results A show that after modification with the composite coating, a microporous structure was constructed on the surface of the magnesium alloy after micro-arc oxidation. EDS spectra indicated that the main elements were O, Mg, and P. However, after loading ICA, the micropores disappeared, resulting in a wrinkled surface, which was attributed to the evaporation of organic solvents during the PTMC encapsulation process. EDS spectra showed that C and O elements were predominantly present, indicating successful PTMC-ICA loading. Finally, after chemical grafting AMPs, SEM images showed a reduction in wrinkles in the organic coating, and EDS spectra confirmed the presence of N elements in MAO-P@IA, indicating successful AMP loading. Simultaneously, SEM analysis of the coating cross-sectional structure was performed. Figure 2 (B) The results show that the average thickness of the constructed MAO layer is 5.1 μm, the average thickness of the P@I layer is 43.7 μm, and the average thickness of the P@IA layer is 44.1 μm. Furthermore, its EDS spectra are identical to those of the surface EDS. FT-IR results ( Figure 2 C) Each coating exhibits its infrared absorption peak, with the MAO coating showing a peak at 424 cm⁻¹. −1 The Mg-O stretching vibration is a typical characteristic band primarily exhibited by the MgO component. The same 988 cm⁻¹ band... −1 PO3 - The stretching vibration of the P=O double bond is a typical characteristic band exhibited by Mg(PO3)2. A band at 1653 cm⁻¹ appears in the FT-IR spectrum of the MAO-P@I coating. -1 The absorption peak of the ketone hydroxyl group is at 1606 cm⁻¹. -1 The absorption peak of the aromatic ring and the bending vibration of the phenolic hydroxyl group are observed at 1260 cm⁻¹. -1 The tensile vibration of OH is at 3370 cm. -1 and 3304 cm -1 The location is obvious, at 2969 cm. -1 Tensile vibrations of CH were observed, which are typical characteristic bands of ICA in the ICA coating. MAO-P@IA exhibits a strong characteristic absorption peak of amide I at 16303 3 cm⁻¹. Further analysis of the composite coating loading was performed using XPS analysis. Figure 2 The results (F) showed that NH and CN antimicrobial peptide characteristic bonds appeared at 399.4 eV and 400.3 eV, confirming the successful loading of AMPs. Static water contact angle tests were conducted to verify the changes in hydrophilicity and hydrophobicity during surface modification. Figure 2 D), the test results showed that AZ31 (102.6°), MAO (43.7°), MAO-P@I (64.8°), and MAO-P@IA (47.1°) exhibited an overall change in hydrophilicity and hydrophobicity, which first decreased, then slightly increased, and then decreased again. The composite coating ultimately exhibited a hydrophilic surface, providing a good attachment site for cell adhesion.

[0057] 2. Corrosion resistance test of the composite coating in Example 1 Magnesium-based bone implant materials from different stages were fabricated into circular pieces with a diameter of 10 mm and a height of 1 mm. The corrosion resistance of the composite coating was evaluated using a three-electrode electrochemical workstation (CHI660E, Shanghai Junzhuo Technology Co., Ltd., China) with amalgam as the reference electrode. The test results are as follows: Figure 3 As shown.

[0058] analyze Figure 3 The polarization curves and impedance results of the magnesium alloy samples show that MAO-P@I and MAO-P@IA have significantly better corrosion resistance, with MAO-P@IA exhibiting the best corrosion resistance.

[0059] Ion release detection experiment To characterize the effect of the composite coating in Example 1 on Mg 2+ The release behavior was regulated by incubating each sample in 1 mL SBF at 37°C for 21 days. The soaking solution was collected and replaced at specific time points. Subsequently, the Mg content in the collected sample solutions was analyzed using inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7700, USA). 2+ The concentration, the results are as follows Figure 4 As shown.

[0060] analyze Figure 4 It can be seen that the Mg in the composite coating (MAO-P@IA) of this invention... 2+ The total release is approximately 35 mg / L, which is released slowly over 21 days, with the release amount fluctuating around 5 mg / L every 3 days.

[0061] Drug release detection experiment The release of icariin from the composite coating was measured using a UV spectrophotometer (JPSJ-606L, Shanghai Rex Instrument Factory, China). The composite coating was prepared using a cylindrical sample with a diameter of 10 mm and a height of 2 mm. The sample was then immersed in 5 mL of SBF for 14 days. The release of ICA was monitored at a wavelength of 270 nm using a UV spectrophotometer. The results are as follows: Figure 5 As shown.

[0062] analyze Figure 5 It can be seen that, compared with ICA concentrations of 1.0, 1.5, and 2.0 mg / mL, the optimal concentration of ICA is 1.5 mg / mL.

[0063] 5. Validation experiment on osteogenic activity of surface-modified coating stem cells in vitro Verification experiment results as follows Figure 6 As shown The results of the composite coating cytotoxicity experiment on BMSCs showed that ( Figure 6 C and Figure 6 (D) When the extract concentration was 25%, the relative viability of BMSCS cells reached over 75%. Notably, the ICA group and the ICA-AMPs composite group showed good cell compatibility at all tested concentrations, with cell viability consistently maintained above 75%. To further evaluate the biocompatibility of the composite coating, we observed the growth of MC3T3-E1 cells using live / dead cell staining. The results showed that a small number of dead cells were observed in all experimental groups after 3 and 5 days of culture, while the cell density in the control group was relatively low at these two time points, indicating that the composite coating exhibited good biocompatibility with the cells.

[0064] The in vitro osteogenic properties of the composite coating were studied, and the results are as follows: Figure 6 As shown in E(2). From the ALP staining results, after 7 days of culture, the staining showed a deeper dark brown color compared to the control group, and quantitative analysis was performed. Figure 6 E(4), MAO-P@I and MAO-P@IA showed an increase of 35-40% in the area of ​​dark brown nodules compared to the control group, and an increase of 25-30% in the area of ​​dark brown nodules compared to the AZ31 group. Further investigation into the in vitro biomineralization properties of the composite coating was conducted. Alizarin Red (ARS) staining of MC3T3-E1 cells cultured in 25% sample extract for 21 days showed that ( Figure 6 E(1)), compared with the AZ31 group, MAO group and control group, the composite coating groups showed a deeper reddish-brown color. ARS quantitative analysis results are as follows: Figure 6E(2), compared with the control group, the area of ​​reddish-brown mineralized calcium nodules in MAO-P@I and MAO-P@IA increased by 40-50%, and the area of ​​reddish-brown mineralized calcium nodules in MAO-P@I and MAO-P@IA increased significantly by 65-70% compared with MAO group. At the same time, quantitative analysis by ALP and ARS staining showed that the staining area of ​​the composite coating after AMP loading decreased by 2-5%, proving that AMP loading had little effect on ICA-induced osteogenic and mineralization.

[0065] To further investigate the in vitro osteogenic properties of the composite coating, mRNA was extracted from cultured BMSCs for qPCR analysis, primarily focusing on its impact on the expression levels of key osteoblast differentiation genes (ALP, RUNX2, OPN, COL-I), such as... Figure 6 F. The results showed that the ALP mRNA expression levels of MAO-P@I and MAO-P@IA were significantly upregulated by 2.5 ± 0.3 times compared with the control group (p < 0.05), indicating that ICA can promote early osteogenic differentiation, enhance alkaline phosphatase activity, and facilitate the initiation of extracellular matrix mineralization. RUNX2 expression reached 4.8 ± 0.5 times that of the control group (p < 0.01), and ICA may drive osteogenic differentiation by activating RUNX2 transcriptional activity. The expression of the mid-to-late stage marker OPN was upregulated by 1.9 ± 0.2 times (p = 0.06), which may be related to extracellular matrix maturation and mineralization. ICA significantly promoted COL-I synthesis (4.1 ± 0.6 times, p < 0.001), indicating that it can effectively stimulate collagen deposition and provide structural support for bone matrix formation. ICA significantly upregulated the expression of osteogenic-related genes, especially the promoting effect on RUNX2 and COL-I, indicating that it has a potential role in promoting osteogenic differentiation.

[0066] 6. In vitro antibacterial verification experiment of composite coating The verification results are as follows Figure 7 As shown.

[0067] The antibacterial properties of the composite coating were analyzed through in vitro antibacterial experiments against Staphylococcus aureus and Escherichia coli. Figure 7 After co-culturing *E. coil* and *S. aureus* with different samples for 6, 12, and 24 hours, bacteria were isolated using standard plate colony isolation techniques to assess the antibacterial activity of the samples. Figure 7A(1). It can be seen that the AZ31 group exhibits certain antibacterial properties, with an antibacterial rate of approximately 85% against both *S. aureus* and *E. coil*. This is presumably due to the corrosion of AZ31 upon contact with the bacterial solution, leading to a local pH increase and the release of metal ions, all of which inhibit bacterial growth. The antibacterial rate of the MAO group decreased to approximately 60%, possibly because the modification of MAO alleviated the rapid corrosion of the magnesium substrate, and MAO itself does not possess antibacterial properties, thus reducing its antibacterial ability. The antibacterial rate of MAO-P@I increased to approximately 95%, attributed to the antibacterial effect of ICA loaded in the coating. After surface grafting with AMPs, the antibacterial ability of MAO-P@IA further increased to approximately 99%. Further verification was performed by performing live / dead fluorescence staining on *S. aureus* and *E. coil* after 24 hours of co-cultivation, as shown in the results... Figure 7 A(2). The results showed that green represented all bacteria and yellow represented dead bacteria. The number of dead bacteria in the MAO-P@I group was significantly higher than that in the AZ31 and MAO groups, further verifying the antibacterial rate of MAO-P@I.

[0068] To evaluate the antibacterial stability of the coating, samples were immersed in PBS simulated body fluid for 3, 5, and 7 days, respectively, and then co-cultured with *S. aureus* and *E. coil* for 24 hours. Characterization was then performed using the plate method. Figure 5 During the immersion process, the antibacterial ability of AZ31 gradually decreased. This may be because corrosion products gradually covered the substrate surface as corrosion occurred, weakening the inhibitory effect on bacteria. The antibacterial rate of the MAO group remained at 50-62%. The antibacterial abilities of MAO-P@I and MAO-P@IA showed a slight decrease, which may be due to drug release during immersion. However, overall, the antibacterial rate of both groups of samples reached over 85%.

[0069] 8. In vivo antibacterial and osteogenic verification experiments of composite coatings A circular bone defect with a diameter of 1.5 mm and a depth of 5 mm was created in the femoral condyle of SD rats using a drill. 10 μL of *S. aureus* at a concentration of 1×10⁻⁶ was injected into the bone defect. 6 CFU bacterial suspension was placed in the defect, then magnesium alloy was placed, and sealed with bone wax. Short-term infection assessment: 3 and 7 days (acute inflammatory phase). Long-term bone regeneration assessment: 8 weeks (osteogenic induction phase). Micro-CT was performed before and after sampling to assess the bone defect area, new bone volume, and bone density. Finally, the specimen was decalcified in 10% EDTA solution for 40 days. After sectioning, the sample was stained with hematoxylin and eosin (H&E). Macroscopic observation of the implantation site was performed on postoperative days 3 and 7 to verify the results. Figure 8 As shown.

[0070] analyze Figure 8 It was found that the group implanted with micro-arc magnesium oxide alloy (PEO) alone showed obvious signs of acute infection, including significant erythema, subcutaneous purulent accumulation, and yellowish-white purulent exudate. In stark contrast, the PEO-P@IA group showed only mild erythema and minimal serous exudate, with no obvious evidence of purulent infection. Quantitative bacteriological analysis of wound exudate collected on postoperative day 7 showed that the number of colony-forming units (CFU) in the PEO-P@IA group was significantly lower than that in the untreated control group and the PEO group (p<0.01), strongly confirming the durable antibacterial efficacy of this composite coating in vivo.

[0071] Micro-CT scan 8 weeks after implantation Figure 8 B) and subsequent analyses of bone mineral density (BMD), bone volume / tissue volume (BV / TV), trabecular separation (Tb.Sp), and bone surface area / bone volume ratio (BS / BV). Results showed significant bone ingrowth into the defect area, with newly formed trabeculae connecting to the host bone. Specifically, at 8 weeks, the BMD of regenerated bone around the PEO-P@IA implant was higher than that of the AZ31 group and the control group. Similarly, the BV / TV ratio showed the same trend. Furthermore, Tb.Sp and BV / BV analyses indicated that the PEO-P@IA group was more conducive to trabecular bone formation around the implant, effectively promoting new bone tissue regeneration. These findings confirm the osteoconductive and / or osteoinductive properties of the coating and its degradation products.

[0072] Histological analysis was performed using hematoxylin-eosin (H&E) and Masson staining to assess peri-implant bone regeneration at 8 weeks post-implantation. Figure 8 C). H&E staining revealed significant new bone formation in the defect area of ​​the PEO-P@IA group, while little or no new bone formation was observed in the AZ31 group and the control group. Masson staining at 4 weeks post-surgery showed blue-stained collagen fiber deposition in the PEO-P@IA group—a fundamental precursor and component of the mature bone matrix—confirming an active and high-quality osteogenesis process. In contrast, no significant collagen fiber proliferation was observed in the AZ31 group and the control group in the early stages.

[0073] 9. Verification experiment to determine whether the composite coating has systemic side effects. Hematoxylin and eosin (H&E) staining was performed on tissue sections of the heart, liver, spleen, lungs, kidneys, and brain from all animal groups in Experiment 8 to assess whether the composite coating had any systemic side effects. The results are as follows: Figure 9 As shown.

[0074] analyze Figure 9The results showed that none of the observed tissues exhibited significant histopathological abnormalities, cell necrosis, or damage. This clearly indicates that the material does not produce systemic toxicity to the receptor.

[0075] The above tests and experimental verifications demonstrate that the surface-modified AZ31 magnesium alloy implant in Example 1 of this invention establishes a novel "sequential" treatment strategy for infected bone defects. The drug-loaded coating based on micro-arc oxidation successfully achieves a triple function: acting as an antibacterial barrier in the critical early stages, transforming into an osteogenic scaffold in the mid-to-late stages of repair, and serving as a protective layer throughout the process to ensure controlled degradation and biocompatibility. This multifunctional, phased-stage characteristic makes this material highly promising for complex orthopedic applications requiring both infection control and robust bone regeneration.

Claims

1. A modified composite coating on the surface of a magnesium-based bone implant material, characterized in that, It includes a micro-arc oxidation ceramic layer covering the surface of the magnesium-based bone implant material, and a bone healing promoting functional layer and an antibacterial functional layer sequentially loaded on the micro-arc oxidation ceramic layer; The bone healing promoting functional layer includes a sustained-release material and icariin encapsulated in the sustained-release material; The antimicrobial functional layer includes antimicrobial peptides; the antimicrobial peptides are grafted onto the bone healing promoting functional layer.

2. The surface-modified composite coating of the magnesium-based bone implant material according to claim 1, characterized in that, In the modified composite coating, the thickness of the micro-arc oxidation ceramic layer is 5-10 μm; the thickness of the bone healing promoting functional layer is 30-40 μm; and the thickness of the antibacterial functional layer is 0.2-0.6 μm.

3. The surface-modified composite coating of the magnesium-based bone implant material according to claim 1, characterized in that, The bone-healing functional layer contains 2-6 mg / cm³ of icariin. 2 .

4. The surface-modified composite coating of the magnesium-based bone implant material according to claim 1, characterized in that, The antibacterial functional layer contains 2-8 mg / cm³ of antibacterial peptides. 2 .

5. A method for preparing a surface-modified composite coating of the magnesium-based bone implant material according to any one of claims 1-4, characterized in that, Includes the following steps: S1: The magnesium-based bone implant material is subjected to micro-arc oxidation treatment to obtain a micro-arc oxidized ceramic layer covering the surface of the magnesium-based bone implant material; S2: A mixture of icariin was coated onto the surface of a magnesium-based bone implant material covered with a micro-arc oxidized ceramic layer and then dried to obtain a micro-arc oxidized ceramic layer and a bone healing promoting functional layer sequentially covering the surface of the magnesium-based bone implant material. S3: The magnesium-based bone implant material covered with a micro-arc oxidation ceramic layer and a bone healing promoting functional layer is immersed and deposited in a solution containing dopamine and polyphenols, and then surface grafted with an antimicrobial peptide solution to obtain a modified composite coating covering the surface of the magnesium-based bone implant material with a micro-arc oxidation ceramic layer, a bone healing promoting functional layer and an antimicrobial functional layer in sequence.

6. The method for preparing the surface-modified composite coating of the magnesium-based bone implant material according to claim 5, characterized in that, In S1, before performing micro-arc oxidation treatment, a pretreatment of the magnesium-based bone implant material is also included; preferably, the pretreatment method includes: polishing the magnesium-based bone implant material with water-based sandpaper, placing it in anhydrous ethanol solution, cleaning it at least twice with an ultrasonic cleaner, and drying it at 35-45°C.

7. The method for preparing the surface-modified composite coating of magnesium-based bone implant material according to claim 5, characterized in that, In S2, the icariin mixed solution includes a solvent, icariin, and a sustained-release material; preferably, the solvent is N,N-dimethylformamide, and the sustained-release material is polylactic acid or polytrimethylene carbonate; the concentration of icariin is 0.5-5.0 mg / mL, and the concentration of polytrimethylene carbonate is 8.5-9.5 mg / mL.

8. The method for preparing the surface-modified composite coating of magnesium-based bone implant material according to claim 5, characterized in that, In S2, the drying process is carried out at a temperature of 55-65°C for 5-7 hours.

9. The method for preparing the surface-modified composite coating of magnesium-based bone implant material according to claim 5, characterized in that, In S3, the concentration of dopamine in the solution containing dopamine and polyphenol is 0.8-2.2 mg / mL, and the concentration of polyphenol is 0.15-0.25 mg / mL.

10. The method for preparing the surface-modified composite coating of the magnesium-based bone implant material according to claim 5, characterized in that, In S3, the antimicrobial peptide solution is a mixed solution of antimicrobial peptide and Tris-HCl buffer, wherein the concentration of the antimicrobial peptide is 0.5-5.0 mg / mL.

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