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Process for preparing compact magnesium oxide/hydroxyapatite nano fiber double-layer coating on surface of magnesium base

A hydroxyapatite and nanofiber technology is applied in the field of preparation of biomedical materials, which can solve the problems of difficulty in blocking body fluid infiltration, low matrix bonding strength and low capacity, and achieves high bonding strength, low price, and early fixation. Effect

Inactive Publication Date: 2012-09-19
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It is known that both magnesium oxide and hydroxyapatite can be slowly degraded in the body fluid environment, but the former has low ability to promote new bone formation, and its coating only plays a role in improving the corrosion resistance of magnesium and magnesium alloy substrates, while the latter promotes new bone formation. The ability of bone formation is higher; on the other hand, the shape of hydroxyapatite has a greater impact on bone formation ability, such as nanorod or fiber shape, which promotes new bone formation more than compact shape
The surface modification methods of magnesium and magnesium alloys reported in the existing literature mainly include micro-arc oxidation, anodic oxidation, electrochemical deposition and hydrothermal treatment, and a composite process of micro-arc oxidation (or anodic oxidation) and electrochemical deposition. The magnesia coating, hydroxyapatite coating, and magnesia / hydroxyapatite double-layer coating formed on the surface of the alloy may have a porous and loose structure that is difficult to block the infiltration of body fluids, or the crystalline form is different from that of the inorganic mineral apatite in bone. The crystalline morphology (nanofibrous) is far apart so that its ability to promote new bone formation is low, or the bonding strength with the matrix is ​​low, and it is easy to peel off during the implantation process, which limits its application

Method used

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  • Process for preparing compact magnesium oxide/hydroxyapatite nano fiber double-layer coating on surface of magnesium base
  • Process for preparing compact magnesium oxide/hydroxyapatite nano fiber double-layer coating on surface of magnesium base
  • Process for preparing compact magnesium oxide/hydroxyapatite nano fiber double-layer coating on surface of magnesium base

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Experimental program
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Effect test

Embodiment 1

[0025] Configured with 0.0137M Ca(OH) 2 , 0.02M β-GP and 0.125M NaOH aqueous solution as electrolyte, magnesium or magnesium alloy as anode, stainless steel as cathode, pulse power supply, constant voltage of 450 volts, initial current density of 2.6 mA / mm2, Micro-arc oxidation treatment was performed for 10 minutes under the condition of frequency of 100 Hz, duty ratio of 26%, and distance between cathode and anode plates of 8 cm to obtain a phosphorus- and calcium-containing porous magnesium oxide coating with a thickness of 15 microns. The SEM photos of its surface and cross-sectional microscopic morphology refer to figure 1 and figure 2 .

Embodiment 2

[0027] The porous magnesium oxide coating containing phosphorus and calcium was prepared by the method in Example 1.

[0028] Add a mixed aqueous solution of 0.05M Ca-EDTA and 0.5M NaOH into the autoclave, and place the phosphorus- and calcium-containing porous magnesium oxide coating formed by micro-arc oxidation in it, and hydrothermally treat it at 90°C for 24 hours . A nanofibrous hydroxyapatite layer grows on the surface of the porous magnesium oxide, and the nanofibers are in the shape of a hexagonal column with a length of about 330.4 nanometers and a diameter of about 193 nanometers. After the combined process of micro-arc oxidation and hydrothermal treatment, the phase composition of the double-layer structure coating is magnesium oxide, magnesium hydroxide and hydroxyapatite.

Embodiment 3

[0030] The porous magnesium oxide coating containing phosphorus and calcium was prepared by the method in Example 1.

[0031] Add a mixed aqueous solution of 0.1M Ca-EDTA and 0.5M NaOH into the autoclave, and place the phosphorus- and calcium-containing porous magnesium oxide coating formed by micro-arc oxidation in it, and hydrothermally treat it at 90°C for 2 hours . The surface layer of the porous magnesium oxide forms a layer of flaky magnesium hydroxide, and the magnesium hydroxide has a sealing effect on the conductive through-holes formed by the micro-arc oxidation treatment. After the combined process of micro-arc oxidation and hydrothermal treatment, the phase composition of the double-layer structure coating is magnesium oxide and magnesium hydroxide. Its surface microscopic morphology and phase composition refer to image 3 and Figure 4 .

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Abstract

The invention discloses a process for preparing compact magnesium oxide / hydroxyapatite nano fiber double-layer coating on the surface of a magnesium base. The process includes firstly preparing porous magnesium oxide coating containing phosphorus and calcium on the surface of magnesium or magnesium alloy by the microarc oxidation technique, namely utilizing phosphorus and calcium containing water solution as electrolyte, subjecting the magnesium or magnesium alloy to microarc oxidation treatment under high voltage by means of a direct-current pulse power source, and then subjecting the porous magnesium oxide coating containing phosphorus and calcium to hydro-thermal treatment in the specific hydro-thermal environment to obtain the magnesium oxide / hydroxyapatite nano fiber double-layer coating. The magnesium oxide / hydroxyapatite nano fiber double-layer coating obtained has the structure of an inner layer (adjacent to a basal body) composed of magnesium oxide and a small amount of magnesium hydrate and being compact and a surface layer formed by nano fiber hydroxyapatite layer, and has the advantages of high bonding strength, fine biological activity and capability of improving corrosion resistance of the magnesium and magnesium alloy in body fluid evidently. Besides, no discontinuous surfaces exist between the double-layer coating and the basal body.

Description

technical field [0001] The invention belongs to the technical field of preparation of biomedical materials, and relates to a preparation technology of a magnesium-based medical implant surface bioactive coating, especially a double-layer structure coating composed of hydroxyapatite nanofibers and dense magnesium oxide micro-arc oxidation and hydrothermal preparation techniques. Background technique [0002] Magnesium and magnesium alloys, as degradable implant materials, have higher specific strength than traditional non-degradable orthopedic implant metal materials (such as titanium alloy, stainless steel, etc.), and their elastic modulus is closer to that of natural bone (3-20GPa). It can avoid the stress shielding effect caused by high elastic modulus metals, especially degradable in the internal environment, and avoids the harm caused by secondary surgery to patients. However, the biggest problem of magnesium alloys as orthopedic implant materials is that their corrosio...

Claims

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Application Information

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IPC IPC(8): C25D11/30A61L27/30A61L27/32
Inventor 憨勇李博
Owner XI AN JIAOTONG UNIV
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