阅读说明：本技术 一种镁合金表面mao-ldh生物复合膜层及制备方法和应用 (Magnesium alloy surface MAO-LDH biological composite membrane layer and preparation method and application thereof ) 是由 王泽鑫 张正一 芦笙 吕伟刚 陈靓瑜 张晋玮 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种镁合金表面MAO-LDH生物复合膜层及制备方法和应用,复合膜层包括镁合金基体、位于镁合金基体表面的MAO膜层以及密集生长于MAO膜层表面的呈六方花瓣状的LDH纳米片层；制备步骤是先将预处理后的镁合金作为阳极浸入到生物电解液中,使用交流脉冲电源和优化的生物电解液进行微弧氧化,制备微弧氧化陶瓷膜层,然后再将微弧氧化陶瓷膜层置于含有配置好的LDH反应液中进行水热处理。本发明制得的生物复合膜层兼具了微弧氧化法和层状双氢氧化物的优点,具有较高耐蚀性和良好生物性能且对环境无污染,同时能够在植入人体的同时释放负载的药物进行治疗,整体制备工艺简单,试剂容易获得,对环境绿色无污染,具有产业化推广前景。(The invention discloses a magnesium alloy surface MAO-LDH biological composite membrane layer and a preparation method and application thereof, wherein the composite membrane layer comprises a magnesium alloy matrix, a MAO membrane layer positioned on the surface of the magnesium alloy matrix and an LDH nano-sheet layer which is densely grown on the surface of the MAO membrane layer and is in a hexagonal petal shape; the preparation steps comprise the steps of immersing the pretreated magnesium alloy serving as an anode into a biological electrolyte, performing micro-arc oxidation by using an alternating current pulse power supply and the optimized biological electrolyte to prepare a micro-arc oxidation ceramic film layer, and then placing the micro-arc oxidation ceramic film layer into a prepared LDH reaction solution for hydrothermal treatment. The prepared biological composite film layer has the advantages of a micro-arc oxidation method and layered double hydroxide, has high corrosion resistance and good biological performance, does not pollute the environment, can be implanted into a human body and release loaded drugs for treatment, has simple integral preparation process, easily obtained reagents, is green and pollution-free to the environment, and has industrial popularization prospect.)

1. A magnesium alloy surface MAO-LDH biological composite membrane layer is characterized in that: the magnesium alloy membrane comprises a magnesium alloy matrix, an MAO membrane layer positioned on the surface of the magnesium alloy matrix and an LDH nano-sheet layer which is densely deposited on the surface of the MAO membrane layer and is in a hexagonal petal shape; the thickness of the MAO membrane layer is 40-50 mu m, the thickness of the LDH nano-sheet layer is 20-70 nm, and the height of the LDH nano-sheet layer deposited on the MAO membrane layer is 600-900 nm.

2. The magnesium alloy surface MAO-LDH biocomposite membrane layer of claim 1, wherein: the porosity of the composite film layer is 5-8%, the surface roughness is 1-1.60 μm, the surface wetting angle is 80-85 DEG, and the impedance value is 7.8 multiplied by 10⁴~8.5×10⁴Ω•cm²The corrosion current density is 1.0 x 10^-6~1.2×10^-6A•cm^-2。

3. The preparation method of the magnesium alloy surface MAO-LDH biological composite membrane layer as claimed in claim 1, which comprises the following steps:

(1) taking a magnesium alloy matrix, and carrying out water grinding, cleaning and drying on the magnesium alloy matrix for later use;

(2) placing a magnesium alloy matrix in a biological electrolyte, and carrying out micro-arc oxidation by taking a magnesium alloy sample as an anode and a stainless steel tank as a cathode to obtain a MAO (nitric oxide) film layer with the surface porosity of 8-10%, the roughness of 2.5-3.5 mu m and the calcium-phosphorus ratio of 0.5-0.7;

(3) preparing LDH reaction liquid, placing the magnesium alloy matrix with the MAO membrane layer in the LDH reaction liquid for hydrothermal reaction, and after the reaction is finished, cleaning the surface and naturally drying to obtain the MAO-LDH biological composite membrane layer.

4. The preparation method of the magnesium alloy surface MAO-LDH biological composite membrane layer as claimed in claim 3, wherein: in the step (2), the biological electrolyte takes deionized water as a solvent and consists of a sodium silicate solution with the concentration of 15-20 g/L, a calcium acetate solution with the concentration of 5-8 g/L, a sodium hexametaphosphate solution with the concentration of 2-4 g/L, a sodium dihydrogen phosphate solution with the concentration of 5-8 g/L, a sodium hydroxide solution with the concentration of 2.5-5 g/L and a sodium metaaluminate solution with the concentration of 10-15 g/L; the biological electrolyte is obtained by dissolving the components in deionized water in sequence.

5. The preparation method of the magnesium alloy surface MAO-LDH biological composite membrane layer as claimed in claim 3, wherein: in the step (2), the micro-arc oxidation conditions are as follows: a constant current mode is adopted, and the current density is 10-20A/dm²The frequency is 500-700 Hz, the duty ratio is 20-40%, the temperature of the biological electrolyte is 30-40 ℃, and the micro-arc oxidation time is 5-10 min.

6. The preparation method of the magnesium alloy surface MAO-LDH biological composite membrane layer as claimed in claim 3, wherein: in the step (3), the LDH reaction solution is specifically prepared as follows: 0.01 to 0.05M of Zn (NO)₃)₂Adding the mixture into a proper amount of deionized water for full dissolution, and adding 9-13M NaOH solution to adjust the pH value of the reaction solution to 12-13.

7. The preparation method of the magnesium alloy surface MAO-LDH biological composite membrane layer as claimed in claim 3, wherein: in the step (3), the temperature of the hydrothermal reaction is 100-150 ℃, and the reaction time is 100-150 min.

8. The use of the magnesium alloy surface MAO-LDH biocomposite membrane layer of claim 1 as a drug carrier in the preparation of a bioimplantation material.

9. The use according to claim 8, wherein the bioimplantation material is prepared by a method comprising: and (2) placing the MAO-LDH biological composite membrane layer in an amino acid reaction solution, performing hydrothermal reaction, keeping the temperature at 60-80 ℃ for 200-250 min, and then cleaning and drying.

10. The use of claim 9, wherein the amino acid reaction solution is specifically formulated as: adding 0.08-0.12M of amino acid into a proper amount of deionized water for fully dissolving, and adding 9-13M of NaOH solution to adjust the pH value of the reaction solution to 9-11.

Technical Field

The invention belongs to a biological composite material and preparation thereof, and particularly relates to a biofilm layer prepared by micro-arc oxidation composite layered double hydroxide and application thereof as a biological implant material.

Background

The magnesium alloy has very wide prospect as a degradable metal applied to a biological implantation material. However, the standard potential of magnesium is low, and the activity of the implanted material is good, so that the magnesium alloy implant has the phenomenon of corrosion in the biological environment too fast, which limits the application of the magnesium alloy implant in clinical medicine. Micro-arc Oxidation (MAO) is a surface treatment method developed based on the traditional anodic Oxidation technology in order to improve the corrosion resistance of the magnesium alloy. It forms ceramic film with matrix oxide as main material on the surface of Mg and other metals in situ through instantaneous high temperature sintering in micro area. The ceramic film and the substrate are metallurgically combined, the inner layer is compact, the corrosion resistance is good, but tiny holes left after current breakdown exist on the surface of the formed film and are accompanied by a small amount of micro cracks, the surface defects provide a large number of corrosion channels for corrosive ions, and the corrosion resistance of the film is seriously reduced. Therefore, it is important to research how to improve the performance of the MAO membrane, which has good corrosion resistance but has defects such as micropores.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a MAO-LDH biological composite membrane which integrates the functions of hole sealing, corrosion inhibition, drug release, self-healing and the like on the surface of a magnesium alloy; the second purpose of the invention is to provide a preparation method of the MAO-LDH biological composite membrane layer; the third purpose of the invention is to provide the application of the MAO-LDH biological composite membrane layer as a biological implant material in the aspect of loading drugs.

The technical scheme is as follows: the invention relates to a magnesium alloy surface MAO-LDH biological composite membrane layer, which comprises a magnesium alloy matrix, a MAO membrane layer positioned on the surface of the magnesium alloy matrix and an LDH nano-sheet layer which is densely grown on the surface of the MAO membrane layer and is in a hexagonal petal shape; the thickness of the MAO membrane layer is 40-50 mu m, the thickness of the LDH nano-sheet layer is 20-70 nm, and the height of the LDH nano-sheet layer deposited on the MAO membrane layer is 600-900 nm.

Furthermore, the porosity of the composite film layer is 5-8%, the surface roughness is 1-1.60 μm, the surface wetting angle is 80-85 DEG, and the impedance value is 7.8 multiplied by 10⁴~8.5×10⁴ Ω•cm²The corrosion current density is 1.0 x 10^-6~1.2×10^-6A•cm^-2。

In the scheme, the micro-arc oxidation ceramic film layer with biocompatibility is prepared on the surface of the magnesium alloy substrate, the micro-arc oxidation ceramic film layer and the micro-arc oxidation ceramic film layer are combined in a metallurgical mode, the corrosion resistance of the magnesium alloy substrate is improved, meanwhile, an LDH nano-sheet layer is further grown and prepared on the surface of the micro-arc oxidation ceramic film layer, the LDH represents double-layer double hydroxide, and the chemical structural formula of the LDH is as follows: [ M ] A²⁺ _1－xM_3+x(OH)₂][A^n－]_x/n·zH₂O, wherein M²⁺And M³⁺Respectively represent divalent and trivalent metal cations, in an octahedral structure constituted by hydroxides, A^n－Is an anion, and the x value of the single-phase LDH is between 0.2 and 0.33. After hydrothermal treatment, the nano-sheet layered structure of the composite membrane layer LDH grows densely and is in a hexagonal petal shape, micro defects on the surface of the MAO membrane layer can be blocked, and Cl which is seriously corroded by magnesium alloy can be captured^－So that the film layer has stronger capability of resisting solution permeation corrosion.

The invention also provides a preparation method of the MAO-LDH biological composite membrane layer on the surface of the magnesium alloy, which comprises the following steps:

(1) taking a magnesium alloy matrix, and carrying out water grinding, cleaning and drying on the magnesium alloy matrix for later use;

(2) placing a magnesium alloy matrix in a biological electrolyte, and carrying out micro-arc oxidation by taking a magnesium alloy sample as an anode and a stainless steel tank as a cathode to obtain a MAO (nitric oxide) film layer with the surface porosity of 8-10%, the roughness of 2.5-3.5 mu m and the calcium-phosphorus ratio of 0.5-0.7;

(3) preparing LDH reaction liquid, placing the magnesium alloy matrix with the MAO membrane layer in the LDH reaction liquid for hydrothermal reaction, and after the reaction is finished, cleaning the surface and naturally drying to obtain the MAO-LDH biological composite membrane layer.

Further, in the step (2), deionized water is used as a solvent for the biological electrolyte, and the biological electrolyte is composed of a sodium silicate solution with a concentration of 15-20 g/L, a calcium acetate solution with a concentration of 5-8 g/L, a sodium hexametaphosphate solution with a concentration of 2-4 g/L, a sodium dihydrogen phosphate solution with a concentration of 5-8 g/L, a sodium hydroxide solution with a concentration of 2.5-5 g/L and a sodium metaaluminate solution with a concentration of 10-15 g/L; the biological electrolyte is obtained by dissolving the components in deionized water in sequence.

Further, in the step (2), the micro-arc oxidation conditions are as follows: a constant current mode is adopted, and the current density is 10-20A/dm²The frequency is 500-700 Hz, the duty ratio is 20-40%, the temperature of the biological electrolyte is 30-40 ℃, and the micro-arc oxidation time is 5-10 min.

Further, in the step (3), the LDH reaction solution is specifically prepared as follows: 0.01 to 0.05M of Zn (NO)₃)₂Adding the mixture into a proper amount of deionized water for full dissolution, and adding 9-13M NaOH solution to adjust the pH value of the reaction solution to 12-13.

Further, in the step (3), the temperature of the hydrothermal reaction is 100-150 ℃, and the reaction time is 100-150 min.

In the scheme, the roughness and the calcium-phosphorus ratio are taken as two important parameters of the micro-arc oxidation film layer, and play an important role in the growth of LDHs. The roughness plays an important role in the subsequent adhesion of LDHs, and the LDHs are difficult to adhere to the surface of the MAO membrane layer due to too small roughness; too large roughness will increase the possibility of film collapse and affect the overall formability of the film, and LDHs can not grow smoothly along cracks and holes on the MAO film. The calcium-phosphorus ratio is used as an evaluation standard of the membrane biological inductivity, the membrane biological inductivity which is closer to the calcium-phosphorus ratio value of human bones is stronger, and the effect of assisting bone repair after being implanted into human bodies is better.

The preparation principle of the invention is as follows: in the preparation process, the generation of the surface of the micro-arc oxidation biofilm layer is controlledThe main factors of the LDH nano-sheet morphology of (A) are the solution ion concentration, the temperature and the time of the hydrothermal process. The LDHs on the surface of the prepared film layer is less in quantity and sparsely distributed under the condition of lower solution concentration, and micropores on the surface of most of the film layer are not effectively covered and plugged; zn (NO) when the concentration of the solution is too high₃)₂And does not provide free ion supply for the growth of the LDHs. LDHs with uneven sizes are distributed on the surface of the MAO/LDHs composite membrane obtained at a lower hydrothermal temperature, the shape of the LDHs is needle-shaped, the LDHs are distributed more densely at the defect positions on the surface of the membrane, and the LDHs are distributed more sparsely on the surface of a flat membrane; the film surface prepared at the overhigh temperature can hardly see the growth of flaky LDHs, and only flocculent LDHs are scattered on the film surface, which is not beneficial to the improvement of the corrosion resistance of the film. The film surface appearance under different hydrothermal time conditions can be different, and due to the irregular distribution of LDHs, the LDHs can realize the plugging of micro defects in parts of micro holes in a mode of cross growth on the surface and growth along the crack wall. Along with the extension of hydrothermal heat preservation time, the LDHs on the surface of the film layer is only distributed in a region with larger local fluctuation of the film layer, the lamellar structure is obviously reduced and distributed in a needle shape, part of holes are exposed, almost no LDHs grow around the holes, the LDHs film layer can not effectively prevent the permeation of solution, and the corrosion resistance of the LDHs film layer can be greatly reduced. Based on the above, in the present invention, LDHs are used in the reaction solution Zn (NO)₃)₂The comprehensive morphology of 0.02M concentration and 2 h heat preservation at 120 ℃ determines that LDH is a hexagonal petal-shaped densely-grown nanosheet layered structure.

Secondly, sodium metaaluminate solution is added in the preparation of the biological electrolyte, mainly because Zn (NO) is adopted₃)₂Preparation of a hydrothermal solution of LDH, Zn (NO)₃)₂Is Zn²⁺Structured LDHs species are combined with screening of main alkaline salt solution of micro-arc oxidation electrolyte, and Al³⁺With Zn²⁺The combination is the most efficient way to synthesize LDH and as such, a certain amount of Al needs to be contained in the MAO membrane layer³⁺Provides a synthetic source, otherwise the LDHs can not grow on the micro-arc oxidation film layer. Therefore, aluminate is preferably selected for additionAnd adding a micro-arc oxidation film layer containing aluminum.

The invention also protects the application of the MAO-LDH biological composite membrane layer on the surface of the magnesium alloy as a drug carrier in the preparation of biological implant materials.

Further, the preparation method of the biological implantation material comprises the following steps: and (2) placing the MAO-LDH biological composite membrane layer in an amino acid reaction solution, performing hydrothermal reaction, keeping the temperature at 60-80 ℃ for 200-250 min, and then cleaning and drying. The amino acid reaction solution is specifically prepared by the following steps: adding 0.08-0.12M of amino acid into a proper amount of deionized water for fully dissolving, and adding 9-13M of NaOH solution to adjust the pH value of the reaction solution to 9-11.

The characteristics of LDH interlayer anion exchange are utilized, and amino acid is adopted to carry out interlayer ion exchange on the MAO-LDH membrane layer, so that on one hand, the amino acid molecule contains S element, and detection is convenient after LDH is inserted and embedded; on the other hand, the amino acid is an ampholyte, contains both an acidic group and a basic group in a molecule, and exists in the form of a zwitterionic or dipolar ion in an aqueous solution or a crystalline form. The charge state of an amino acid depends on the pH of the environment, and changing the pH can make the amino acid positively or negatively charged. In a basic environment, the isoelectric point of amino acids shifts, when the amino acids are predominantly present in the anionic form. Therefore, in an alkaline hydrothermal environment, amino acid is a substance with the function of completing interlayer anion exchange, and is used as a substance for LDH intercalation to prepare a synthetic organic LDH membrane layer. After ion exchange, amino acids having macromolecular chains replace the interlayer NO of LDH₃ ^－Ions and LDH continue to crystallize in the hydrothermal alkaline environment, the interlayer spacing of LDH is shortened in the process, and the agglomerated LDH of the composite membrane layer can effectively block penetration of corrosive ions and delay the corrosion rate of the composite membrane layer due to the slow release effect of amino acid, so that the corrosion resistance of the membrane layer is further improved. By inserting substances or ions with different functions into the interlayer, the purposes of biocompatibility, drug release control, corrosion resistance and the like are achieved.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:

(1) the LDH on the surface of the film layer is distributed in a petal shape, so that the pore defects and the like on the film layer can be densely blocked, the film layer has stronger solution permeation corrosion resistance, the corrosion resistance of the magnesium alloy implant can be effectively prolonged, and the service life of the material implant is prolonged.

(2) Due to the characteristics of in-situ growth and the adjustability of composition and structure of the LDH film layer, the LDH film layer can grow in situ at the defects such as cracks through a chemically synthesized cation framework, the Ca/P of the LDH composite film layer is about 0.8-0.9, the Ca/P of the LDH composite film layer is improved to a certain extent compared with a micro-arc oxidation film layer, and when the LDH film layer is positioned in a corrosive medium, Cl which seriously corrodes magnesium alloy can be captured between layers^－And the nano-container can be used as a nano-container to store some corrosion-inhibiting substances (such as amino acid drugs), and interlayer substances can be released according to needs, so that the nano-container not only can treat the affected part of a patient, but also can protect a film layer.

(3) The invention adopts cysteine to be inserted into LDH interlamination and replaces anion NO between the LDH interlamination₃ ^－The thickness of the LDH-Cys nano-sheet layer is 30-80 nm, the total deposited height is 700-1000 nm, the Ca/P of the surface film layer is about 0.7-0.75, and the resistance value of the film layer is improved to a certain extent compared with that of a micro-arc oxidation film layer, and is 9.00 multiplied by 10⁴~9.20×10⁴ Ω·cm²The corrosion current density is 7.8 multiplied by 10^-7~8.0×10^-7A·cm^-2The corrosion rate of the sample can be reduced while the drug is loaded.

(4) The biological composite film obtained by the invention has the advantages of a micro-arc oxidation method and layered double hydroxide, has higher corrosion resistance and good biological performance, has no pollution to the environment, and can release loaded drugs for treatment while being implanted into a human body. The invention has simple integral preparation process, easily obtained reagents, environmental protection and no pollution, and has industrialized popularization prospect.

Drawings

FIG. 1 is a schematic diagram of the LDH-MAO composite membrane layer obtained by the present invention;

FIG. 2 is a microscopic surface topography of the MAO membrane layer and LDH-MAO composite membrane layer prepared in example 1;

FIG. 3 is a graph of Nyquist impedances for MAO membrane layer, LDH-MAO complex membrane layer, and LDH-Cys complex membrane layer;

FIG. 4 is a schematic XRD analysis of the LDH-MAO composite membrane layer prepared in example 1;

FIG. 5 is a schematic element scan of the LDH-Cys composite membrane layer prepared in the example;

FIG. 6 is a chemical functional group in an LDH-Cys complex membrane layer;

figure 7 is an LDH membrane layer that did not grow successfully.

Detailed Description

The technical solution of the present invention will be described in further detail with reference to examples.

Example 1

(1) Surface pretreatment of a magnesium alloy sample: processing the ZK60 magnesium alloy into a sample of 15mm multiplied by 5mm by wire cutting, water-grinding the surface of the sample by using 600#, 1000# and 1500# sandpaper in sequence, then ultrasonically cleaning the sample by using alcohol and deionized water, and then drying for later use;

(2) micro-arc oxidation treatment: placing the magnesium alloy sample in the step (1) in biological electrolyte, taking the magnesium alloy sample as an anode, a stainless steel tank as a cathode, and keeping the temperature of the electrolyte at 35-40 ℃ and the current density at 10A/dm²The micro-arc oxidation biomembrane layer has the working frequency of 600Hz and the duty ratio of 30 percent, and has the micro-arc oxidation for 5min, the roughness of 2.93 mu m and the calcium-phosphorus ratio of 0.62; the biological electrolyte is prepared by sequentially dissolving components in deionized water, wherein the deionized water is used as a solvent, the biological electrolyte is composed of a sodium silicate solution with the concentration of 17g/L, a calcium acetate solution with the concentration of 6g/L, a sodium hexametaphosphate solution with the concentration of 2g/L, a sodium dihydrogen phosphate solution with the concentration of 5g/L, a sodium hydroxide solution with the concentration of 2.5g/L and a sodium metaaluminate solution with the concentration of 10 g/L;

(3) preparing an LDH reaction solution: 0.02M of Zn (NO)₃)₂Adding the mixture into a proper amount of deionized water for full dissolution, and adding 10M NaOH solution to adjust the pH value of the reaction solution to 12.5;

(4) vertically placing the micro-arc oxidized sample into a polytetrafluoroethylene lining of a hydrothermal reaction kettle, adding the mixed reaction liquid to the position between 1/3 and 2/3 of the volume of the lining, vertically placing the polytetrafluoroethylene lining into a stainless steel reaction kettle shell, screwing a kettle cover by using a lever, and respectively preserving heat for 120 minutes in an electric heating constant-temperature air-blast drying box at the set temperature of 120 ℃. After the hydrothermal treatment is finished, the surface of the sample is cleaned by deionized water, and the sample is vertically placed on a table top to wait for the natural drying of the surface of the sample, so that an LDH-MAO composite membrane layer is obtained, as shown in figure 1, after the hydrothermal treatment, the layered structure of the nano sheets of the LDH composite membrane layer grows densely and is in a hexagonal petal shape, the tiny defects on the surface of the membrane layer can be blocked, the membrane layer has strong capability of resisting the osmotic corrosion of a solution, the corrosion resistance of a magnesium alloy implant can be effectively prolonged, and the service life of the material implant is prolonged. In the embodiment, the surface of the magnesium alloy sample is pretreated, and the magnesium alloy sample is subjected to micro-arc oxidation treatment, so that the corrosion resistance of a magnesium alloy matrix is improved, and the magnesium alloy sample has certain roughness and micropores, a good base layer is provided for subsequent hydrothermal treatment, and the binding force between composite film layers is effectively improved.

In the prepared LDH-MAO composite membrane layer, the thickness of the MAO membrane layer is 45.3 mu m, the thickness of the LDH nano-sheet layer is 68 nm, and the total deposition height is 866 nm; the porosity of the composite film layer is 7.5%, the surface roughness is 1.45 μm, the surface wetting angle is 82.56 °, and the impedance value is 8.20 × 10⁴ Ω•cm². The original magnesium alloy substrate, the MAO membrane layer and the MAO membrane layer are subjected to polarization curve test, and the corrosion current density of the final LDH-MAO composite membrane layer is 1.18 multiplied by 10^-6 A•cm^-2。

Referring to fig. 2, fig. 2(a) shows MAO membrane and fig. 2(b) shows LDH-MAO composite membrane, it can be seen that MAO membrane surface is occupied by molten material, is rugged and forms "crater" morphology, which indicates that MAO membrane surface still has significant defects, and after corrosion medium contacts membrane, it contacts matrix through micropores or holes, resulting in decrease of corrosion resistance. The LDH-MAO composite membrane has the advantages that the defects on the surface of the LDH-MAO composite membrane layer are almost covered by LDHs, a small number of large micropores and microcracks are not completely covered by LDHs, the outline of the LDHs can be seen on the figure, and the growth of LDHs lamella can still be seen in the depths of the defects of the micropores or the microcracks, so that the LDHs on the surface of the LDH-MAO composite membrane layer is uniform and compact in growth, the porosity of the membrane layer can be greatly reduced, and the corrosion resistance of the membrane layer is improved.

Referring to FIG. 5, the Ca/P ratio on the surface of LDH-MAO composite membrane is about 0.83, which is elevated compared to the MAO membrane; referring to FIG. 4, CaMgP with less intense diffraction peaks can be detected in the MAO/LDH diffractogram₂O₇And (4) a crystal phase, which shows that initial hydrothermal reaction conditions do not destroy micro-arc calcium phosphate oxide products with biocompatibility in the film layer.

Example 2

The preparation is the same as example 1, and the difference is that:

the micro-arc oxidation current density in the step (2) is 15A/dm²The frequency is 650Hz, the duty ratio is 20 percent, and the micro-arc oxidation time is 7 min. Other parameters were the same as in example 1.

The composite film obtained in the embodiment has uniform and compact appearance, the surface of the prepared magnesium alloy is provided with a micro-arc oxidation film layer with the thickness of 47 mu m, the thickness of the LDH nano-sheet layer is 55 nm, and the height of the deposition layer is 802 nm. The porosity of the composite film layer is 7.1%, the roughness is 1.16 μm, the surface wetting angle is 83.65 degrees, the Ca/P of the surface film layer is 0.85, and the impedance value of the film layer is 7.92 multiplied by 10⁴ Ω•cm²Compared with the micro-arc oxidation film layer, the micro-arc oxidation film layer shows better calcium-phosphorus ratio, biological activity and osteoinduction.

Example 3

The preparation is the same as example 1, and the difference is that:

the biological electrolyte in the step (2) takes deionized water as a solvent and consists of a sodium silicate solution with the concentration of 15g/L, a calcium acetate solution with the concentration of 5g/L, a sodium hexametaphosphate solution with the concentration of 4g/L, a sodium dihydrogen phosphate solution with the concentration of 8g/L, a sodium hydroxide solution with the concentration of 5g/L and a sodium metaaluminate solution with the concentration of 9 g/L. Other parameters were the same as in example 1. Other parameters were the same as in example 1.

The composite film obtained in the embodiment has uniform and compact appearance, the surface of the prepared magnesium alloy is provided with a micro-arc oxidation film layer with the thickness of 49 mu m, the thickness of the LDH nano-sheet layer is 42 nm, and the height of the deposition layer is 679 nm. The porosity of the composite film layer is 6.4 percent, coarseRoughness of 1.36 μm, surface wetting angle of 84.43 °, surface film layer Ca/P of 0.81, and film layer impedance of 7.95 × 10⁴Ω•cm²Compared with the micro-arc oxidation film layer, the micro-arc oxidation film layer shows better calcium-phosphorus ratio, biological activity and osteoinduction.

Example 4

The preparation is the same as example 1, and the difference is that:

in the step (4), the heat preservation temperature is 110 ℃, and the heat preservation time is 100 minutes. Other parameters were the same as in example 1.

The composite film obtained in the embodiment has uniform and compact appearance, the surface of the prepared magnesium alloy has a micro-arc oxidation film layer with the thickness of 44 microns, the thickness of the LDH nano-sheet layer is 55 nm, and the thickness of the deposition layer is 784 nm. The porosity of the composite film layer is 7.2%, the roughness is 1.10 μm, the Ca/P of the surface film layer is 0.85, the wetting angle is 83.32 degrees, and the impedance value of the film layer is 8.01 multiplied by 10⁴And omega cm2, compared with the micro-arc oxidation film layer, the micro-arc oxidation film layer shows better calcium-phosphorus ratio, biological activity and osteoinduction.

Example 5

The preparation is the same as example 1, and the difference is that:

in the step (3), the preparation of the LDH reaction solution is as follows: 0.05M Zn (NO3)2 was added to an appropriate amount of deionized water to dissolve it sufficiently, and 9M NaOH solution was added to adjust the pH of the reaction solution to 13. Other parameters were the same as in example 1.

The composite film obtained in the embodiment has uniform and compact appearance, the surface of the prepared magnesium alloy is provided with a micro-arc oxidation film layer with the thickness of 43 mu m, the thickness of the LDH nano-sheet layer is 70 nm, and the thickness of the deposition layer is 898 nm. The porosity of the composite film layer is 7.8%, the roughness is 1.58 μm, the Ca/P of the surface film layer is 0.87, the wetting angle is 80.77 degrees, and the impedance value of the film layer is 7.91 multiplied by 10⁴Ω•cm²。

Example 6

A 0.1M cysteine (Cys) solution was prepared with deionized water, then the pH was adjusted to 10 with NaOH solution, the LDH-MAO composite membrane layer prepared in example 1 was vertically placed at the bottom of a teflon liner in a stainless steel reaction vessel, and the mixed reaction solution was added to a volume between 1/3 and 2/3 to assemble the reaction vessel. And (3) preserving the heat for 240 minutes in a constant-temperature blast drying oven, setting the heat preservation temperature to be 60 ℃, and obtaining the LDHs-Met and LDHs-Cys composite membrane layer containing the cysteine (Cys) intercalation by utilizing the interlayer ion exchange effect of LDH.

The composite film obtained by the embodiment has uniform and compact appearance, the surface of the prepared magnesium alloy has a nano-sheet layered structure which is in hexagonal petal-shaped dense growth, the thickness of the LDH nano-sheet layer is 69 nm, and the thickness of the deposition layer is 852 nm. The porosity of the LDHs-Cys composite film layer is 5.6%, the roughness is 1.94 mu m, and the impedance value of the film layer is 9.09 multiplied by 10⁴Omega cm2, compared with the micro-arc oxidation film layer, the coating has better corrosion resistance, biological activity and osteoinduction. See FIG. 6, at 1440 cm^-1And the spectrum of the LDHs-Cys film layer has a C-S stretching vibration peak which is relatively sharp, and the C-S functional group is also derived from cysteine, so that the film layer contains intercalated amino acid. In addition, the spectrum of the film was 1350 cm^-1Can observe NO₃ ^-The absorption vibration peak of (A) shows NO between LDHs layers after hydrothermal treatment at 60 ℃ for 4 h₃ ^－And not completely substituted by cysteine. The characterization analysis of XRD and FT-IR shows that cysteine is successfully inserted into the interlayer structure of LDHs, the protective effect of the film layer on the matrix is stronger, and the biocompatibility is better.

Comparative example 1

(1) Surface pretreatment of a magnesium alloy sample: processing the magnesium alloy into a pattern of 15mm multiplied by 5mm by wire cutting, grinding the surface of a sample with 600#, 1000# and 1500# sandpaper in sequence, then ultrasonically cleaning the sample with alcohol and deionized water in sequence, and then drying for later use;

(2) micro-arc oxidation treatment: placing the magnesium alloy sample in the step (1) in biological electrolyte, taking the magnesium alloy sample as an anode, a stainless steel tank as a cathode, and keeping the temperature of the electrolyte at 35-40 ℃ and the current density at 10A/dm²Micro-arc oxidation is carried out for 5min under the conditions that the working frequency is 500Hz and the duty ratio is 40 percent; the single micro-arc oxidation layer obtained has loose and porous surface, and compared with the LDH-MAO composite membrane layer of example 3, the Ca/P of the surface membrane layer is about 0.43, and referring to FIG. 3, the resistance value of the MAO membrane layer is 6.55 ×10⁴Ω•cm²Impedance value of 8.45X 10, which is smaller than that of example 3⁴Ω•cm²The film prepared by the single micro-arc oxidation method has poor corrosion resistance and low biological activity.

Comparative example 2

(1) Surface pretreatment of a magnesium alloy sample: processing the magnesium alloy into a pattern of 15mm multiplied by 5mm by wire cutting, grinding the surface of a sample with 600#, 1000# and 1500# sandpaper in sequence, then ultrasonically cleaning the sample with alcohol and deionized water in sequence, and then drying for later use;

(2) micro-arc oxidation treatment: placing the magnesium alloy sample in the step (1) in biological electrolyte, taking the magnesium alloy sample as an anode, a stainless steel tank as a cathode, and keeping the temperature of the electrolyte at 35-40 ℃ and the current density at 10A/dm²The working frequency is 500Hz, the micro-arc oxidation is carried out for 5min, two groups of comparison experiments are carried out, and the duty ratios are respectively set to be 20% and 60%; when the duty ratio of the obtained single micro-arc oxidation layer is set to be 20%, the Ca/P of the surface film layer is about 0.43, and the roughness is 2.21 mu m; when the duty ratio is set to 60%, the Ca/P ratio of the surface film layer is about 0.99, and the roughness is 3.65 μm.

(3) Preparing an LDH reaction solution: 0.02M of Zn (NO)₃)₂Adding the mixture into a proper amount of deionized water for full dissolution, and adding 10M NaOH solution to adjust the pH value of the reaction solution to 12.5; the heat preservation temperature is 120 ℃, and the heat preservation time is 120 minutes. Other parameters were the same as in example 1. The duty ratio is 20%, the Ca/P ratio of the surface film layer is about 0.43, and the roughness is 2.21 μm, so that almost no LDHs are attached to the flat area, and only a small amount of LDHs are distributed around the holes. The duty ratio is set to 60%, the Ca/P ratio of the surface membrane layer is about 0.99, and when the roughness is 3.65 mu m, the LDHs nanosheets are hardly seen on the surface of the MAO membrane layer to be attached to the membrane layer.

Comparative example 3

(1) The micro-arc oxidation treatment was the same as in example 1;

(2) preparing an LDH reaction solution: 0.06M of Zn (NO)₃)₂Adding the mixture into a proper amount of deionized water for full dissolution, and adding 10M NaOH solution to adjust the pH value of the reaction solution to 12.5; the heat preservation temperature is 110 ℃, and the heat preservation time is 100 minutes. Other ginsengThe number is the same as in example 1. The obtained membrane layer is shown in fig. 7, and it can be seen from the figure that the number of LDHs on the surface of the membrane layer prepared under the concentration is small and the distribution is sparse, and micropores on the surface of most of the membrane layer are not effectively covered and blocked. Compared with the MAO/LDHs composite membrane layer prepared at 0.02M, the LDHs grown in situ on the surface of the membrane layer basically has no protection effect on the MAO membrane layer. It can be seen that Zn (NO) is present in excessive concentration₃)₂And does not provide free ion supply for the growth of the LDHs. At this time, Ca/P of the surface film layer was about 0.67, and the impedance value of the film layer was 7.42X 10⁴Ω•cm²And the resistance value is smaller than that of the embodiment 3, and the corrosion resistance of the prepared film is poorer and the biological activity is lower when the ion concentration is higher.

Comparative example 4

(1) Surface pretreatment of a magnesium alloy sample: processing the magnesium alloy into a pattern of 15mm multiplied by 5mm by wire cutting, grinding the surface of a sample with 600#, 1000# and 1500# sandpaper in sequence, then ultrasonically cleaning the sample with alcohol and deionized water in sequence, and then drying for later use;

(2) micro-arc oxidation treatment: placing the magnesium alloy sample in the step (1) in a biological electrolyte, wherein the component of the magnesium alloy sample is 0.8 g/L (NaPO)₃)₆、6 g/L Na₂SiO₃·9H₂O、0.5 g/L Ca(CH₃COO)₂·H₂O、0.5 g/L NaH₂PO₄·H₂O and NaOH (adjusting electrolyte pH). Taking a magnesium alloy sample as an anode, a stainless steel tank as a cathode, the temperature of the electrolyte is 35-40 ℃, and the current density is 10A/dm²The working frequency is 500Hz, the duty ratio is 30 percent, and the micro-arc oxidation is carried out for 7 min; the obtained single micro-arc oxidation layer has loose and porous surface, the Ca/P of the film layer is about 0.48, and the impedance value of the MAO film layer is 24731 omega cm²The roughness was 2.19 μm and the wetting angle was 84 °.

(3) Preparing an LDH reaction solution: 0.02M of Zn (NO)₃)₂Adding the mixture into a proper amount of deionized water for full dissolution, and adding 10M NaOH solution to adjust the pH value of the reaction solution to 12.5; the heat preservation temperature is 120 ℃, and the heat preservation time is 120 minutes. Other parameters were the same as in example 1. No growth of LDHs on the MAO membrane layer was observed,indicating that LDHs can not be prepared without using the sodium metaaluminate system electrolyte.