Composite coating modified medical magnesium matrix as well as preparation method and application thereof

Abstract

The invention discloses a composite coating modified medical magnesium matrix and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a silane hydrolysis solution with a nano calcium carbonate suspension to obtain a mixed solution; soaking the medical magnesium matrix pretreated by the layered double hydroxide coating in the mixed solution for 1-5 minutes, and then quickly taking out; and heating the impregnated medical magnesium matrix at the temperature of 80-150 DEG C to 45-80 DEG C to obtain the modified medical magnesium matrix. Firstly, a layered double hydroxide coating is generated on the surface of medical magnesium or magnesium alloy through a hydrothermal method, and then a nano calcium carbonate composite silane coating is prepared on the layered double hydroxide coating, so that the corrosion resistance of a matrix is improved, and meanwhile, due to compounding of nano calcium carbonate, the biocompatibility and osteogenesis performance of the matrix are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface modification of biomedical metal materials, and relates to a composite coating-modified medical magnesium substrate, a preparation method and application thereof, and specifically to a nano-calcium carbonate composite silane coating-layered double hydroxide coating synergistically modified medical magnesium substrate, a preparation method and application thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Medical magnesium and its alloys, with their mechanical properties similar to those of human bone and excellent biodegradability, are expected to become a new generation of orthopedic implant materials, eliminating the need for secondary surgical removal. However, their rapid degradation rate can lead to premature implant failure during the recovery period. Furthermore, hydrogen generated during magnesium alloy corrosion, elevated local pH, and excessive magnesium ion concentrations can hinder tissue healing, hindering their clinical application.

[0004] Layered double hydroxide (LDH) is used as a pretreatment coating for magnesium-based implants due to its corrosion resistance, controlled biodegradability, and biocompatibility. LDH's unique ion exchange capacity enables it to capture aggressive anions from the environment, effectively slowing the corrosion process of the substrate. However, LDH's inherent layered porous structure also provides pathways for the penetration of corrosive media.

[0005] In addition, as an orthopedic implant material, it is required to have good biocompatibility and osteogenic properties, but the relevant properties of the layered double hydroxide coating are still difficult to meet the application requirements. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a composite coating modified medical magnesium substrate and its preparation method and application.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a method for preparing a composite coating-modified medical magnesium substrate, comprising the following steps: mixing the silane hydrolysis solution with the nano-calcium carbonate suspension to obtain a mixed solution; Soaking the medical magnesium substrate pretreated with the layered double hydroxide coating in the mixed solution for 1-5 minutes and then quickly taking it out; The impregnated medical magnesium matrix is ​​heated at 80-150° C. for 45-80 minutes to obtain a modified medical magnesium matrix.

[0008] The silane film obtained by hydrolysis has a loose structure and contains a large amount of water, resulting in the uncured silane film having almost no corrosion resistance. Appropriate temperature can accelerate the dehydration condensation between internal molecules to form a stable three-dimensional spatial structure.

[0009] The inherent layered porous structure of the LDH coating is a channel for the penetration of corrosive media. The nano-scale calcium carbonate particles have a small particle size and can effectively penetrate and fill the pores and microcracks of the LDH coating, significantly increasing the tortuosity of the path for the corrosive media to reach the magnesium substrate, forming a denser physical barrier, hindering the diffusion and transmission of corrosive ions, and thus slowing down the corrosion rate of the substrate.

[0010] Calcium ions are the main inorganic component of bones. Nano-calcium carbonate will slowly release calcium ions in a physiological environment or slightly acidic conditions. The released calcium ions can activate calcium-sensing receptors on the cell membrane and promote the adhesion, spreading and proliferation of osteoblasts.

[0011] Calcium ions are an important regulatory factor in the key signaling pathway of osteogenic differentiation. They can upregulate the expression of osteogenic-related genes and promote bone matrix mineralization. Nano-calcium carbonate can also provide essential biomineral ions and create a microenvironment that is more conducive to cell survival and function.

[0012] After silane is hydrolyzed, silanols are generated. These silanols can undergo condensation reactions with the -OH groups on the substrate surface, or condense between silanol molecules to form a three-dimensional cross-linked Si-O-Si network structure; forming a continuous and dense film that covers the surface of LDH and nano-calcium carbonate particles, providing excellent physical barriers to prevent water molecules, oxygen and corrosive substances from directly contacting the coating interior and the magnesium matrix.

[0013] Silane molecules usually carry hydrophobic groups such as alkyl chains. These hydrophobic groups are arranged outward, which significantly improves the hydrophobicity of the coating surface, greatly hinders the wetting and penetration of aqueous solutions, and further improves corrosion resistance.

[0014] Silane is bonded to the LDH substrate through chemical bonds or strong hydrogen bonds, forming a dense Si-O-Si network inside the silane molecules. The silane molecules can also wrap and infiltrate nano-sodium carbonate particles, significantly improving the interfacial bonding strength between the composite coating and the LDH substrate, as well as the cohesive force of the coating itself, reducing the risk of peeling of the coating under stress or environmental conditions, and ensuring long-term protection.

[0015] Silane acts as a binder and film-forming agent, tightly wrapping and bonding the dispersed nano-calcium carbide particles together and firmly anchoring them on the LDH substrate, forming a dense organic-inorganic hybrid network structure, effectively reducing the penetrating pores and defects in the coating, and forming a highly dense, low-porosity composite barrier.

[0016] Nano-calcium carbonate, a rigid filler dispersed within the silane matrix, enhances and toughens the coating, improving its hardness, wear resistance, and impact resistance. Silane, a flexible binder, firmly binds the nano-calcium carbonate particles through chemical bonds and physical entanglement, tightly adhering them to the LDH substrate. The resulting composite coating significantly improves its mechanical strength, toughness, adhesion to the substrate, and wear resistance, reducing the risk of coating failure due to physical damage and extending its protective lifespan.

[0017] The dense silane network hinders the rapid penetration of body fluids, making the dissolution of nano-calcium carbonate and the release of calcium ions a slow and controllable process, continuously providing biological signals that promote osteogenic differentiation while maintaining the long-term stability of the coating as a whole.

[0018] In some embodiments, the silane hydrolysis solution is prepared by mixing water, anhydrous ethanol, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and ethyl orthosilicate in proportion, adjusting the pH value to 4-6.5 with glacial acetic acid, and hydrolyzing for 24-72 hours to obtain a silane hydrolysis solution.

[0019] Preferably, the volume ratio of water, anhydrous ethanol, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and ethyl orthosilicate is 8-16:8-16:15-25:15-25.

[0020] Preferably, during the hydrolysis process, magnetic stirring is continuously performed at a speed of 300-600 r / min.

[0021] In some embodiments, the dispersion liquid of the nano-calcium carbonate suspension is anhydrous ethanol.

[0022] Preferably, the dispersion method of the nano-calcium carbonate suspension is: continuous magnetic stirring at a speed of 300-600 r / min for 1-5 hours, and then ultrasonic dispersion for 10-60 minutes.

[0023] In some embodiments, the volume ratio of the silane hydrolysis solution to the nano-calcium carbonate suspension is 20-30:1.

[0024] In some embodiments, the method for pretreating the medical magnesium substrate with the layered double hydroxide coating is as follows: polishing the medical magnesium substrate with 600#, 1000#, and 2000# sandpaper in sequence; After polishing, ultrasonic cleaning was performed with acetone, anhydrous ethanol, and deionized water in sequence; The cleaned medical magnesium substrate is immersed in an aluminum nitrate solution and subjected to a hydrothermal reaction for a set time. After the reaction is completed, the substrate is rinsed and dried to obtain the medical magnesium substrate.

[0025] Preferably, the temperature of the hydrothermal reaction is 110-130° C., and the time of the hydrothermal reaction is 10-15 h.

[0026] Preferably, the medical magnesium matrix is ​​medical magnesium or a magnesium alloy.

[0027] In a second aspect, the present invention provides a composite coating-modified medical magnesium substrate prepared by the preparation method.

[0028] In a third aspect, the present invention provides the use of the composite coating-modified medical magnesium substrate in the preparation of orthopedic implants.

[0029] The beneficial effects achieved by one or more embodiments of the present invention are as follows: A layered double hydroxide coating is generated on the surface of medical magnesium or magnesium alloy by a hydrothermal method, and then a nano-calcium carbonate composite silane coating is prepared thereon, thereby improving the corrosion resistance of the substrate. At the same time, the biocompatibility and osteogenic properties of the substrate are improved due to the composite of nano-calcium carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 Scanning electron micrograph (a) and energy spectrum (b) of the nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with the layered double hydroxide coating prepared in Example 1; Figure 2 In the figure, (a) is a scanning electron micrograph of a medical magnesium substrate after immersion in simulated body fluid for 14 days; (b) is a scanning electron micrograph of a medical magnesium substrate pretreated with a layered double hydroxide coating after immersion in simulated body fluid for 14 days; (c) is a scanning electron micrograph of a nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with a layered double hydroxide coating prepared in Example 1 after immersion in simulated body fluid for 14 days; Figure 3 In the figure, (a) is the adhesion test result of the medical magnesium substrate to mouse bone marrow mesenchymal stem cells after culturing for 24 hours; (b) is the adhesion test result of the medical magnesium substrate pretreated with the layered double hydroxide coating to mouse bone marrow mesenchymal stem cells after culturing for 24 hours; (c) is the adhesion test result of the nano-calcium carbonate composite silane coating on the surface of the medical magnesium substrate pretreated with the layered double hydroxide coating prepared in Example 1 to mouse bone marrow mesenchymal stem cells after culturing for 24 hours.

[0032] Figure 4In the figure, (a) is the alizarin red staining result of mouse bone marrow mesenchymal stem cells cultured on the medical magnesium substrate for 14 days; (b) is the alizarin red staining result of mouse bone marrow mesenchymal stem cells cultured on the medical magnesium substrate pretreated with the layered double hydroxide coating for 14 days; (c) is the alizarin red staining result of mouse bone marrow mesenchymal stem cells cultured on the medical magnesium or magnesium alloy surface pretreated with the layered double hydroxide coating prepared in Example 1 for 14 days. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0034] The present invention will be further described below with reference to the embodiments.

[0035] Example 1 A method for preparing a nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with a layered double hydroxide coating, the specific steps of which are as follows: 1) The preparation process of the substrate material is as follows: The medical magnesium substrate was polished with 600#, 1000#, and 2000# sandpaper in sequence; Ultrasonic cleaning was performed with acetone, anhydrous ethanol, and deionized water for 5 min, respectively; The cleaned medical magnesium substrate was immersed in 50 mL of 0.02 mol / L Al(NO3)3 solution and hydrothermally reacted at 120 ℃ for 12 h. It was then rinsed with deionized water and dried to obtain a medical magnesium substrate pretreated with a layered double hydroxide coating.

[0036] 2) Mix 12 ml of deionized water, 12 ml of anhydrous ethanol, 20 ml of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 20 ml of ethyl orthosilicate, adjust the pH to 5.50 with glacial acetic acid, and hydrolyze for 48 hours to prepare a silane hydrolysis solution; 3) Disperse 0.5 g of nanohydroxyapatite particles in 10 ml of anhydrous ethanol to obtain a nano-calcium carbonate suspension; 4) Mix 48 ml of the hydrolyzed silane solution with 2 ml of the nano-calcium carbonate suspension; 5) The LDH-pretreated medical magnesium substrate was immersed in a nano-calcium carbonate-silane solution for 2 min, then pulled out at a uniform speed and heated at 120 °C for 60 min to obtain a nano-calcium carbonate composite silane coating on the surface of the medical magnesium substrate pretreated with the layered double hydroxide coating.

[0037] Figure 1 Scanning electron micrograph and energy spectrum of the nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with the prepared layered double hydroxide coating. As shown in (a) and (b), the nano-calcium carbonate composite silane coating has been successfully prepared.

[0038] Figure 2 In the figure, (a) is a scanning electron micrograph of a medical magnesium substrate after immersion in simulated body fluid for 14 days; (b) is a scanning electron micrograph of a medical magnesium substrate pretreated with a layered double hydroxide coating after immersion in simulated body fluid for 14 days; (c) is a scanning electron micrograph of a nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with a layered double hydroxide coating prepared in Example 1 after immersion in simulated body fluid (the composition of the simulated body fluid is: 8.035 g / L NaCl, 0.335 g / L NaHCO3, 0.225 g / L KCl, 0.231 g / L K2HPO4·3H2O, 0.311 g / L MgCl2·6H2O, 0.292 g / L CaCl2, 0.072 g / L Na2SO4, and 6.118 g / L (CH2OH)3CNH2) for 14 days. Figure 2 It can be seen that after 14 days of immersion in simulated body fluid, the medical magnesium substrate and the medical magnesium substrate pretreated with layered double hydroxide coating have been severely corroded; in comparison, the medical magnesium substrate protected by the nano-calcium carbonate composite silane coating is relatively less corroded, and apatite particles are generated on the surface, indicating that the nano-calcium carbonate composite silane coating enhances the corrosion resistance and bioactivity of the medical magnesium substrate.

[0039] The samples sterilized by UV for 12 h were placed in a 24-well culture plate, and 1×10 4 pieces / cm 2 The cell suspension was prepared by placing the cell culture plate in a cell culture incubator at 37°C and 5% CO2. After 24 hours of culture, the culture medium was removed and the cells were washed with PBS. The cells were then fixed with 4% paraformaldehyde for 20 minutes and rinsed with PBS. A rhodamine-phalloidin solution was added to the sample surface to stain the cells. The cells were incubated at room temperature in the dark for 30 minutes. After rinsing with PBS, the cells were stained with DAPI for 30 seconds. Finally, the samples were washed with PBS to remove nonspecifically bound dyes and observed under a laser confocal scanning microscope to visualize the adherent cytoskeleton.

[0040] Figure 3In the figure, (a) is the adhesion test result of the medical magnesium substrate to mouse bone marrow mesenchymal stem cells after culturing for 24 hours; (b) is the adhesion test result of the medical magnesium substrate pretreated with the layered double hydroxide coating to mouse bone marrow mesenchymal stem cells after culturing for 24 hours; (c) is the adhesion test result of the nano-calcium carbonate composite silane coating on the surface of the medical magnesium substrate pretreated with the layered double hydroxide coating prepared in Example 1 to mouse bone marrow mesenchymal stem cells after culturing for 24 hours.

[0041] The samples sterilized by UV for 12 h were placed in a 24-well culture plate, and 1×10 4 pieces / cm 2 The cell suspension was cultured for 14 days after osteogenic induction, and the samples were removed and washed with PBS; 4% paraformaldehyde was added, fixed at 4°C for 10 minutes, and washed with PBS; 1% alizarin red stain was added, stained at room temperature for 5-10 minutes, and the excess dye was washed with PBS to remove it. After drying, the samples were observed using a fluorescence microscope.

[0042] Figure 4 In the figure, (a) is the alizarin red staining result of mouse bone marrow mesenchymal stem cells cultured on the medical magnesium substrate for 14 days; (b) is the alizarin red staining result of mouse bone marrow mesenchymal stem cells cultured on the medical magnesium substrate pretreated with the layered double hydroxide coating for 14 days; (c) is the alizarin red staining result of mouse bone marrow mesenchymal stem cells cultured on the medical magnesium or magnesium alloy surface pretreated with the layered double hydroxide coating prepared in Example 1 for 14 days.

[0043] Figure 3 and Figure 4 It was demonstrated that the nano-calcium carbonate composite silane coating had the best biocompatibility and osteogenic properties.

[0044] Example 2 A method for preparing a nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with a layered double hydroxide coating, the specific steps of which are as follows: 1) The preparation process of the substrate material is as follows: The medical magnesium alloy substrate was polished with 600#, 1000#, and 2000# sandpaper in sequence; Ultrasonic cleaning was performed with acetone, anhydrous ethanol, and deionized water for 5 min, respectively; The cleaned medical magnesium alloy substrate was immersed in 50 mL of 0.02 mol / L Al(NO3)3 solution and hydrothermally reacted at 120 ℃ for 10 h. It was then rinsed with deionized water and dried to obtain a medical magnesium alloy substrate pretreated with a layered double hydroxide coating.

[0045] 2) Mix 10 ml of deionized water, 16 ml of anhydrous ethanol, 18 ml of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 13 ml of ethyl orthosilicate, adjust the pH to 5.30 with glacial acetic acid, and hydrolyze for 50 h to prepare a silane hydrolysis solution; 3) Disperse 0.3 g of nanohydroxyapatite particles in 10 ml of anhydrous ethanol to obtain a nano-calcium carbonate suspension; 4) Mix 48 ml of the hydrolyzed silane solution with 2 ml of the nano-calcium carbonate suspension; 5) The LDH-pretreated medical magnesium alloy substrate was immersed in a nano-calcium carbonate-silane solution for 3 min, then pulled out at a constant speed and heated at 110 °C for 45 min to obtain a nano-calcium carbonate composite silane coating on the surface of the medical magnesium alloy substrate pretreated with the layered double hydroxide coating.

[0046] Example 3 A method for preparing a nano-calcium carbonate composite silane coating on the surface of a medical magnesium substrate pretreated with a layered double hydroxide coating, the specific steps of which are as follows: 1) The preparation process of the substrate material is as follows: The medical magnesium substrate was polished with 600#, 1000#, and 2000# sandpaper in sequence; and ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 5 min respectively; The cleaned medical magnesium substrate was immersed in 50 mL of 0.02 mol / L Al(NO3)3 solution and hydrothermally reacted at 120 ℃ for 12 h. It was then rinsed with deionized water and dried to obtain a medical magnesium substrate pretreated with a layered double hydroxide coating.

[0047] 2) Mix 15 ml of deionized water, 15 ml of anhydrous ethanol, 20 ml of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 17 ml of ethyl orthosilicate, adjust the pH to 6.00 with glacial acetic acid, and hydrolyze for 60 h to prepare a silane hydrolysis solution; 3) Disperse 0.2 g of nanohydroxyapatite particles in 10 ml of anhydrous ethanol to obtain a nano-calcium carbonate suspension; 4) Mix 48 ml of the hydrolyzed silane solution with 2 ml of the nano-calcium carbonate suspension; 5) The LDH-pretreated medical magnesium substrate was immersed in a nano-calcium carbonate-silane solution for 4 min, then pulled out at a uniform speed and heated at 115 °C for 50 min to obtain a nano-calcium carbonate composite silane coating on the surface of the medical magnesium substrate pretreated with the layered double hydroxide coating.

[0048] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a composite coating-modified medical magnesium substrate, characterized in that: The steps include: mixing the silane hydrolysis solution with the nano-calcium carbonate suspension to obtain a mixed solution; Soaking the medical magnesium substrate pretreated with the layered double hydroxide coating in the mixed solution for 1-5 minutes and then quickly taking it out; The impregnated medical magnesium matrix is ​​heated at 80-150° C. for 45-80 minutes to obtain a modified medical magnesium matrix.

2. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, characterized in that: The preparation method of the silane hydrolysis solution is as follows: water, anhydrous ethanol, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and ethyl orthosilicate are mixed in proportion, the pH value is adjusted to 4-6.5 with glacial acetic acid, and hydrolyzed for 24-72 hours to obtain a silane hydrolysis solution; Preferably, the volume ratio of water, anhydrous ethanol, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and ethyl orthosilicate is 8-16:8-16:15-25:15-25; Preferably, during the hydrolysis process, magnetic stirring is continuously performed at a speed of 300-600 r / min.

3. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, characterized in that: The dispersing liquid of the nano calcium carbonate suspension is anhydrous ethanol.

4. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, wherein: The dispersion method of the nano calcium carbonate suspension is: continuous magnetic stirring at a speed of 300-600 r / min for 1-5 hours, and then ultrasonic dispersion for 10-60 minutes.

5. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, characterized in that: The volume ratio of the silane hydrolysis solution to the nano-calcium carbonate suspension is 20-30:

1.

6. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, wherein: The method for pretreating the medical magnesium substrate with the layered double hydroxide coating is as follows: the medical magnesium substrate is polished with 600#, 1000# and 2000# sandpaper in sequence; After polishing, ultrasonic cleaning was performed with acetone, anhydrous ethanol, and deionized water in sequence; The cleaned medical magnesium substrate is immersed in an aluminum nitrate solution and subjected to a hydrothermal reaction for a set time. After the reaction is completed, the substrate is rinsed and dried to obtain the medical magnesium substrate.

7. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 110-130° C., and the time of the hydrothermal reaction is 10-15 hours.

8. The method for preparing a composite coating-modified medical magnesium substrate according to claim 1, characterized in that: The medical magnesium matrix is ​​medical magnesium or magnesium alloy.

9. A composite coating modified medical magnesium substrate, characterized by: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the composite coating-modified medical magnesium substrate according to claim 9 in the preparation of orthopedic implants.

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