CN114921831B

CN114921831B - Method for preparing micro-arc oxidation coating

Info

Publication number: CN114921831B
Application number: CN202210574345.2A
Authority: CN
Inventors: 唐金成; 严明; 骆小平
Original assignee: Southwest University of Science and Technology
Current assignee: Southwest University of Science and Technology
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2023-10-03
Anticipated expiration: 2042-05-25
Also published as: CN114921831A

Abstract

The invention belongs to the technical field of surface modification, and discloses a method for preparing a micro-arc oxidation coating. The method specifically comprises the following steps: placing a titanium sample in a calcium-phosphorus-sodium-silver electrolyte, and performing micro-arc oxidation to obtain a double-layer porous graded micro-arc oxidation coating; the calcium-phosphorus-sodium-silver electrolyte comprises sodium hexametaphosphate, silver nitrate, calcium acetate and monocalcium phosphate. The invention adopts a one-step micro-arc oxidation method to prepare the double-layer porous graded coating, the operation steps are simple and easy, silver nitrate is contained in the electrolyte, silver ions can be oxidized to form nano silver particles in the micro-arc oxidation process, so that the titanium-based implant plays a long-term antibacterial role in the initial stage of implantation, and calcium, phosphorus and sodium elements in the electrolyte can improve the bioactivity of the surface of the implant, thereby accelerating the ingrowth and mineralization maturation of bones.

Description

Method for preparing micro-arc oxidation coating

Technical Field

The invention belongs to the technical field of surface modification, and particularly relates to a method for preparing a micro-arc oxidation coating.

Background

In current clinical practice, bone and tooth implantation is still challenged with both aseptic loosening and infectious bone defects. A key factor leading to aseptic loosening is the formation of fibrous capsules at the interface between the implant and bone tissue rather than the newly formed bone. Studies have shown that 22% of orthopaedic implant revision surgery failures are due to implant infection. Thus, the preparation of multifunctional bone regeneration materials with antibacterial properties and high bone-promoting properties for bone defect repair is probably one of the most promising strategies.

Titanium (Ti) and its alloys are widely used in the preparation of orthopedic implants due to their excellent mechanical strength and good biocompatibility. However, one of the main problems of medical titanium-based implants is their bio-inertness, which greatly reduces the clinically expected performance of the implant. To address this problem, researchers have employed various surface modification strategies such as grit blasting, plasma spraying, and micro-arc oxidation (MAO). MAO is an electrochemical surface treatment technique that uses plasma discharge to grow a ceramic film in situ on the surface of metals such as titanium, aluminum, magnesium and vanadium. This process can create a large number of micro-scale volcanic pore structures in the implant surface to promote bone tissue regeneration.

In addition, bioactive elements such as silver, calcium, and phosphate may be incorporated simultaneously into the coating from the electrolyte to achieve the desired biological function. Nano silver particles (AgNPs) deposited on the surface of the MAO coating were reported to significantly promote the antimicrobial effect of the implant. There have been studies on the use of a two-step or three-step MAO process to prepare a hierarchical dual pore structure coating which is effective in promoting bone integration but lacking in its long-term effective antibacterial properties, and in order to improve its antibacterial properties, a large number of researchers have constructed a layer of drug-carrying platform of Polydopamine (PDA) on the implant surface to achieve more loading and slow release of AgNPs. However, to achieve both antimicrobial and osteogenic properties of titanium implants, multiple surface modifications are often required, which is cumbersome and not efficient.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems in the prior art described above. Therefore, the invention provides a method for preparing the micro-arc oxidation coating, and the multifunctional titanium micro-arc oxidation coating with bacteriostasis and bone promotion can be prepared by using one-step micro-arc oxidation.

According to one aspect of the present invention, a method of preparing a micro-arc oxidation coating is presented, comprising the steps of:

placing a titanium sample in a calcium-phosphorus-sodium-silver electrolyte, and performing micro-arc oxidation to obtain a double-layer porous graded micro-arc oxidation coating; the calcium-phosphorus-sodium-silver electrolyte comprises sodium hexametaphosphate ((NaPO) ₃ ) ₆ ) Silver nitrate (AgNO) ₃ ) Calcium acetate (Ca (CH) ₃ COO) ₂ ·H ₂ O), calcium biphosphate (Ca (H) ₂ PO ₄ ) ₂ ·H ₂ O)。

According to a preferred embodiment of the invention, there is at least the following advantageous effect:

the double-layer porous graded coating is prepared by adopting a one-step micro-arc oxidation method, and the operation steps are simple and feasible; the electrolyte contains silver nitrate, silver ions can be oxidized to form nano silver particles in the micro-arc oxidation process, so that the titanium-based implant plays a long-term antibacterial role in the initial stage of implantation, and calcium, phosphorus and sodium elements introduced into the electrolyte can also improve the bioactivity of the implant surface, so that bone ingrowth and mineralization maturation are accelerated. The micro-arc oxidation coating prepared by the method has wide application prospect in the treatment of infectious bone defects and bone plastic surgery.

In some embodiments of the invention, the titanium sample comprises either pure titanium or a titanium alloy.

In some preferred embodiments of the invention, the titanium sample comprises any one of TA1, TA2, TA3, TA4 or TC4 titanium alloy.

In some embodiments of the present invention, the surface of the titanium sample is polished and cleaned, and then placed in the calcium-phosphorus-sodium-silver electrolyte.

In some embodiments of the present invention, the polishing process specifically includes: sequentially polishing with 600 mesh, 800 mesh, 1000 mesh and 2000 mesh silicon carbide sand paper.

In some embodiments of the present invention, the cleaning specifically includes the following steps: sequentially ultrasonically cleaning the polished titanium sample for 8-10 min by using acetone, alcohol and distilled water.

In some preferred embodiments of the present invention, the cleaning specifically comprises the steps of: and sequentially ultrasonically cleaning the polished titanium sample for 10min by using acetone, alcohol and distilled water.

In some embodiments of the invention, the sodium hexametaphosphate concentration is 8 to 10g/L.

In some preferred embodiments of the invention, the sodium hexametaphosphate concentration is 10g/L.

In some embodiments of the invention, the silver nitrate is present at a concentration of 1 to 1.5g/L.

In some preferred embodiments of the invention, the concentration of silver nitrate is 1g/L.

Silver ions in the silver nitrate are oxidized into silver atoms in the micro-arc oxidation process, nano silver particles are further formed, after the titanium-based implant containing the micro-arc oxidation coating is implanted into a required position, the silver atoms are slowly oxidized by oxygen to release free silver ions, and the silver ions are combined with mercapto groups on bacterial walls to block respiratory chains of bacteria, so that bacteria attached to the surface of the titanium-based implant are finally killed.

In some embodiments of the invention, the calcium acetate is present at a concentration of 6.5 to 8.5g/L.

In some preferred embodiments of the invention, the calcium acetate is at a concentration of 8.5g/L.

In some embodiments of the invention, the concentration of the monocalcium phosphate is 6.5 to 7.5g/L.

In some preferred embodiments of the invention, the concentration of the monocalcium phosphate is 6.5g/L.

In some embodiments of the invention, the calcium-phosphorus-sodium-silver-based electrolyte is maintained in a stirred state as the micro-arc oxidation is performed.

In some embodiments of the invention, the calcium-phosphorus-sodium-silver-based electrolyte has a temperature of 40 ℃ or less when the micro-arc oxidation is performed.

In some embodiments of the invention, the micro-arc oxidation takes the titanium sample as an anode and an electrolytic cell as a cathode; the material of the electrolytic tank comprises any one of stainless steel, carbon steel or nickel.

In some embodiments of the invention, the micro-arc oxidized power supply is set to a constant voltage mode.

In some embodiments of the invention, the conditions of the microarc oxidation are: the forward voltage is 350-400V, the frequency is 450-500 Hz, and the duty ratio is 10-15%.

In some preferred embodiments of the invention, the conditions of the micro-arc oxidation are: the forward voltage was 400v, the frequency was 500Hz, and the duty cycle was 10%.

In some embodiments of the invention, the time of the micro-arc oxidation is 10 to 15 minutes.

In some preferred embodiments of the invention, the time of the micro-arc oxidation is 10 minutes.

O in electrolyte during micro-arc oxidation ^2- And PO (PO) ₄ ^3- TiO on the surface of the titanium sample and making directional movement under the action of electric field ₂ And continuously depositing an oxide layer and a formed discharge channel. While Ca ²⁺ And Ag ⁺ With constant electrolyte agitation, the grown TiO can be deposited by diffusion and electrophoresis ₂ On the oxide layer, with PO ₄ ^3- Reacting and forming an outer apatite-like layer; the formation of disordered micro-scale pores of the outer layer of the phosphor-like soot layer is due to the destruction and exfoliation of the coating by the plasma discharge at a voltage of 350-400V. With the increase of time, the micro-arc oxidation coating grows continuously, and finally the double-layer porous graded coating is formed. In addition, during the micro-arc oxidation, the frequency should be kept between 450 and 500Hz, and a proper frequency helps to construct a distinct double-layer porous graded coating. The frequency is too low, so that the discharge time is too long, the energy is too high, the formation of an outer layer is easy to damage, and the aperture of an inner layer is increased; conversely, the frequency is too high, so that the discharge time is too short, the energy is too low, the pore diameters of the outer layer pores and the inner layer pores are smaller, and the construction of the double-layer porous graded coating is not facilitated.

In some embodiments of the invention, in the double-layer porous graded micro-arc oxidation coating, the pores of the outer layer are larger and unevenly distributed, and the pore diameter of the pores of the outer layer is 5-10 μm; the pores of the inner layer show a volcanic pore morphology, and the pore diameter of the pores of the inner layer is 200-1000 nm.

In some preferred embodiments of the invention, in the bilayer porous hierarchical structure, the outer layer pores have a pore size of about 10 μm and the inner layer pores have a pore size of about 400nm.

In some embodiments of the present invention, after the double-layer porous graded micro-arc oxidation coating is prepared, the micro-arc oxidation coating needs to be cleaned and dried, and specifically includes the following steps: and (3) flushing the micro-arc oxidation coating by distilled water, and drying in an electrothermal blowing drying oven.

Drawings

The invention is further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a scanning electron microscope image of a micro-arc oxidation coating prepared in example 1 of the present invention; the right is a partial enlarged view of the left; the left scale is 50 μm and the right scale is 5 μm;

FIG. 2 is an energy spectrum analysis (EDS) chart of a micro-arc oxidation coating prepared in example 1 of the present invention; the scale is 5 μm;

FIG. 3 is a schematic diagram of a double-layer porous hierarchical structure of a micro-arc oxidation coating prepared in example 1 of the present invention;

FIG. 4 is an in vitro silver ion release profile of MTi/Ag/Cap samples immersed in SBF solution for 336h (14 days) in the test example of the present invention;

FIG. 5 is a graph showing the antibacterial effect of CP-Ti and MTi/Ag/Cap samples on E.coli and Staphylococcus aureus in the test examples of the present invention; wherein E represents Escherichia coli, and S represents Staphylococcus aureus;

FIG. 6 is a graph showing the effect of CP-Ti and MTi/Ag/Cap samples on osteosarcoma cell proliferation in the test example of the present invention;

FIG. 7 is a graph showing alizarin red staining of ECM on the surface of samples of CP-Ti and MTi/Ag/Cap and a graph showing quantitative results of mineralization in the test example of the present invention; the upper part is an alizarin red staining chart, the scale is 100 μm, and the lower part is a quantitative result chart;

FIG. 8 is a graph of the quantitative results of three-dimensional reconstructed images of implant and surrounding new bone tissue and Bone Mineralization Density (BMD) and bone volume fraction (BV/TV) of new bone tissue 8 weeks after surgery in a test example of the present invention; wherein the scale in the three-dimensional reconstructed image is 500 μm.

Detailed Description

The following detailed description of embodiments of the invention is exemplary, and is provided merely to illustrate the invention and should not be construed as limiting the invention.

In the description of the present invention, unless explicitly defined otherwise, terms such as polishing, incubation, etc. should be construed broadly, and those skilled in the art can reasonably ascertain the specific meaning of the terms in the present invention by combining the specific details of the technical scheme.

In the description of the present invention, reference to the term "one embodiment," "some embodiments," etc., means that a particular feature, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment. Furthermore, the particular features, materials, or characteristics may be combined in any suitable manner in any one or more embodiments.

The test methods used in the examples are conventional methods unless otherwise specified; the materials, reagents and the like used, unless otherwise specified, are those commercially available.

Example 1

The micro-arc oxidation coating is prepared by the embodiment, and the specific process is as follows:

the titanium sample was selected from 10mm 2mm commercial pure titanium (TA 2) and was processed as follows:

(1) Sequentially polishing the titanium sample by using 600-mesh, 800-mesh, 1000-mesh and 2000-mesh silicon carbide sand paper, and then sequentially ultrasonically cleaning the polished titanium sample by using acetone, alcohol and distilled water for 10min to remove surface impurities;

(2) Taking the cleaned titanium sample as an anode, placing the anode in a calcium-phosphorus-sodium-silver electrolyte (comprising 10g/L of sodium hexametaphosphate, 1g/L of silver nitrate, 8.5g/L of calcium acetate, 6.5g/L of monocalcium phosphate and distilled water), setting a power supply in a constant voltage mode, carrying out micro-arc oxidation under the conditions of 400V forward voltage, 500Hz frequency and 10% duty ratio, stirring the whole oxidation process, keeping the temperature of the electrolyte below 40 ℃, and carrying out micro-arc oxidation for 10min to obtain a double-layer porous graded micro-arc oxidation coating after the micro-arc oxidation is finished;

(3) Washing the micro-arc oxidation coating with distilled water, and drying in an electrothermal blowing drying oven to obtain the titanium sample (MTi/Ag/Cap) coated with the micro-arc oxidation coating.

The surface morphology of the above titanium sample containing the micro-arc oxidation coating, i.e., the morphology of the micro-arc oxidation coating, was observed using a scanning electron microscope (SEM, SU8230, hitachi, japan) at an accelerating voltage of 5kV, and was determined by an energy chromatograph X-ray fluorescence spectrometer (EDX, oxford X-max 50,Oxford Instruments,UK) attached to the SEM, and the results are shown in fig. 1, 2, and 3. Fig. 1 is an SEM image of a micro-arc oxidation coating, fig. 3 is a schematic diagram of a double-layer porous hierarchical structure of the micro-arc oxidation coating, and fig. 1 and 3 show that the pores of the outer layer of the coating are larger, are micro-pores and are unevenly distributed, and the pore diameter of the pores of the outer layer is 10 μm; the pores of the inner layer are in classical 'volcanic pore' morphology and are nano-pores, the pore diameter of the pores of the inner layer is 400nm, and in addition, the enrichment of nano-silver particles can be observed on the surface of the coating. FIG. 2 is an energy spectrum analysis (EDS) of a micro-arc oxidized coating, showing that Ag, ca and P elements are successfully introduced into the coating, and it can be judged that the outer layer of the implant is a porous apatite-like coating and the inner layer is TiO ₂ A layer.

This structure of the micro-arc oxidation coating is mainly due to the difference of electrolyte and electrolysis parameters: o in electrolyte during micro-arc oxidation ^2- And PO (PO) ₄ ^3- TiO on the surface of the titanium sample and making directional movement under the action of electric field ₂ And continuously depositing an oxide layer and a formed discharge channel. While Ca ²⁺ And Ag ⁺ With constant electrolyte agitation, the grown TiO can be deposited by diffusion and electrophoresis ₂ On the oxide layer, with PO ₄ ^3- An apatite-like layer (see fig. 3) that reacts and forms an outer layer; the formation of disordered micro-scale pores of the outer layer of the phosphor-like soot layer is due to the destruction and exfoliation of the coating by the plasma discharge at a voltage of 350-400V. And as time increases, the micro-arc oxidation coating grows continuously, and finally a double-layer porous graded coating is formed. In addition, during the micro-arc oxidation, the frequency should be maintainedAt 450-500 Hz, a suitable frequency aids in the construction of a distinct bilayer porous graded coating. The frequency is too low, so that the discharge time is too long, the energy is too high, the formation of an outer layer is easy to damage, and the aperture of an inner layer is increased; conversely, the frequency is too high, so that the discharge time is too short, the energy is too low, the pore diameters of the outer layer pores and the inner layer pores are smaller, and the construction of the double-layer porous graded coating is not facilitated.

Example 2

the titanium sample was selected from 10mm 2mm commercial pure titanium (TA 4) and was processed as follows:

(2) Taking the cleaned titanium sample as an anode, placing the anode in a calcium-phosphorus-sodium-silver electrolyte (comprising 9g/L of sodium hexametaphosphate, 1.3g/L of silver nitrate, 7.5g/L of calcium acetate, 7g/L of monocalcium phosphate and distilled water), setting a power supply in a constant voltage mode, carrying out micro-arc oxidation under the conditions of 350V forward voltage, 480Hz frequency and 12% duty ratio, stirring the whole oxidation process, keeping the temperature of the electrolyte below 40 ℃, and carrying out micro-arc oxidation for 10min to obtain a double-layer porous graded micro-arc oxidation coating after the micro-arc oxidation is finished;

(3) Washing the micro-arc oxidation coating with distilled water, and drying in an electrothermal blowing drying oven to obtain the titanium sample with the micro-arc oxidation coating on the surface.

Test examples

This test example tests the performance of the micro-arc oxidized coating prepared in example 1 and titanium samples containing the micro-arc oxidized coating. Wherein:

1. ion release of micro-arc oxidized coatings

Placing the MTi/Ag/Cap sample into a centrifuge tube containing 5mL of simulated body fluid (SBF, including sodium chloride, potassium chloride, dipotassium hydrogen phosphate, magnesium chloride, calcium chloride, tris, sodium bicarbonate and pH=7.4), placing the centrifuge tube into a 37 ℃ incubator, continuously shaking (80 rpm) for culture, taking out 1mL of SBF solution at specific time points (1, 3, 6, 24, 48, 72, 120, 168, 240 and 336 h), and simultaneously supplementing 1mL of fresh SBF solution into the centrifuge tube, so as to ensure that the total volume in the centrifuge tube is always 5 mL. The measurement of 1mL of the SBF solution taken out was performed by an inductively coupled plasma mass spectrometer (ICP-MS, model EXPEC 7000), and the result was obtained by repeating the measurement three times, and the result is shown in FIG. 4. In fig. 4, the release rate is faster within 24 hours, and then the release rate is slower. Thus, the use of the titanium sample in implantation surgery, the abrupt release of nano-silver particles on the MTi/Ag/CaP sample coating, is very beneficial for the initial implantation of surgery, and it avoids the occurrence of infection as much as possible; and then slowly released for a long time, the method can also help to reduce the risk of recurrence of infection so as to reduce the pain of patients caused by secondary operation.

2. Evaluation of antibacterial Properties

The same immersing process was also carried out on an untreated titanium sample (CP-Ti) as in test example 1, and on the basis of the ion release test, the immersed CP-Ti and MTi/Ag/Cap samples for 1, 120 and 336 hours were taken out, respectively, for the test of antibacterial properties. The antibacterial property is detected by a coating dilution method, namely 2 multiplied by 10 ⁵ cfu bacterial suspensions (two bacterial suspensions: E.coli and S.aureus were used) 1mL was placed in a 24-well tissue culture polystyrene dish (titanium sample after having been placed out), incubated for 24h at 37℃in an incubator with a relative humidity of 90, and then gently rinsed 3 times with 1mL of Phosphate Buffer (PBS) to remove unattached bacteria. Then placing the titanium sample into a centrifuge tube containing 5mL of PBS, and carrying out vortex for 1min to separate adhered bacteria and prepare bacterial suspension; after 1mL of the bacterial suspension was diluted 1000-fold, 100. Mu.L of the diluted solution was removed and spread evenly on a plate containing LB medium (1% w/v tryptone, 0.5% w/v beef extract, 0.5% w/v sodium chloride and 2% w/v agar), and after incubation at 37℃for 24 hours, the colony count was calculated and the average was repeated three times, and the result was shown in FIG. 5. FIG. 5 shows that MTi/Ag/Cap samples have sustained and effective antibacterial performance compared to CP-Ti samples, showing a antibacterial rate of 95.5% on day 1, and a antibacterial effect of approximately 70% on day 14This lays a good foundation for bacteriostasis and treatment of infectious bone defects. And the sustained effective bacteriostatic rate is mainly attributed to the sustained slow release behavior of silver ions in the coating.

3. Osteoblast cytotoxicity evaluation

Osteosarcoma cells (MG-63) were cultured at a ratio of 4X 10 ⁴ Cell/well density was inoculated onto the surface of CP-Ti and MTi/Ag/Cap samples (placed in culture plates) and cultured with 500. Mu.L MEM medium (10% fetal bovine serum, 100U/mL penicillin G, 100mg/mL streptomycin sulfate, 0.25mg/mL amphotericin B) per well. The cytotoxicity was measured by CCK-8 method after 1, 3, 5d with replacement of fresh medium every 2d, i.e., 50. Mu.L of CCK-8 solution was added dropwise to the original medium, incubated at 37℃for 1h, then yellow formamide reaction product was transferred to 96-well plates, and absorbance of each well was measured at 450nm wavelength using an enzyme-labeled instrument (IMink, BIO-RAD, china) to characterize cell proliferation, and the results were averaged three times in FIG. 6. FIG. 6 shows that the proliferation rate of cells on the MTi/Ag/Cap samples is obviously higher than that on the CP-Ti samples in the 1 st, 3 rd and 5d (especially 5 d), which shows that the micro-arc oxidation coating prepared by the invention can obviously promote the proliferation of cells and shows stronger bioactivity.

4. In vitro evaluation of extracellular matrix (ECM) mineralization

In vitro matrix mineralization is an advanced indicator of osteogenic differentiation in osteoinduction medium, where ECM mineralization was observed using alizarin red (ARS, solarbio, china) staining. MG-63 cells were grown at 4X 10 ⁴ Cell/well density was seeded on the surface of CP-Ti and MTi/Ag/Cap samples (placed in culture plates) in osteoinductive medium containing 10mM beta-glycerophosphate, 0.3mM ascorbic acid and 100nM dexamethasone (Sigma, USA) and incubated for 21d at 37 ℃. After the incubation, the samples were washed 3 times with PBS, then fixed with 4% paraformaldehyde for 15min, stained with alizarin red (2%, ph=4.3, 400 μl) at room temperature for 15min, rinsed with deionized water and free dye removed, and the mineralization of the cell ECM was observed with an optical microscope (DM 2700M, leica, germany). Finally, 10% cetylpyridinium chloride is used for extraction and Ca 2h is combined, and the absorbance of the obtained solution is measured at 562nm wavelength toMineralization of ECM was characterized and the average was repeated three times and the results are shown in figure 7. In fig. 7, alizarin red mainly stains mineralized nodules, and the staining result shows that the surface of the MTi/Ag/Cap sample is deeper in staining, the mineral deposition is thicker, and the quantitative result is consistent with the staining result, so that the micro-arc oxidation coating on the surface of the MTi/Ag/CaP sample can obviously promote the differentiation of osteoblasts and the mineralization of matrixes.

5. In vivo implant trial evaluation

SPF-grade healthy SD male rats (8 weeks old, average weight 350-400 g) are selected for constructing the model for repairing the distal metaphyseal bone defect of femur. The whole operation process is performed under a sterile environment, and rats are anesthetized by inhalation of isoflurane (the concentration is maintained to be 3%), and meloxicam (10 mu L/10g body weight) is subcutaneously injected into the rats after anesthesia to perform postoperative analgesia. Shaving and disinfecting the right hind limb of the rat, and cutting the skin and muscle above the femur by 10X 5mm to expose the distal metaphyseal of the femur; a1.5 mm drill was used to drill a cylindrical bone defect of 1.5mm diameter and 2mm depth, and the fractured bone pieces were washed with physiological saline. Sterile CP-Ti and MTi/Ag/Cap implants (1.5X1.5X12 mm) were implanted into the bone defect, and incisions were sutured layer by layer. Wherein, the dosages of intramuscular injection penicillin and oral carprofen during operation and after operation are 6000U/kg and 4mg/kg respectively, which last for 3 days. After 8 weeks, rats were euthanized and the implants and surrounding new bone tissue were harvested for further Micro-CT analysis and the average was repeated three times, as shown in fig. 8. FIG. 8 shows that a small amount of new bone tissue appears around the CP-Ti implant, while there is more new bone tissue production and thicker bone trabecular structure around the MTi/Ag/Cap implant; in addition, in the quantitative analysis result of Micro-CT, the Bone Mineralization Density (BMD) and the bone volume fraction (BV/TV) of bone tissue around the MTi/Ag/Cap implant are significantly higher than those of bone tissue around the CP-Ti implant, which indicates that the MTi/Ag/CaP implant has excellent osteogenic performance in vivo.

Therefore, the method for preparing the multifunctional titanium micro-arc oxidation coating with bacteriostasis and bone promotion by the one-step method is a simple, quick and efficient environment-friendly surface treatment method, and has wide application prospect in the future of treating infectious bone defect and bone plastic surgery.

While the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. Furthermore, embodiments of the invention and features of the embodiments may be combined with each other without conflict.

Claims

1. A method of preparing a micro-arc oxidation coating comprising the steps of:

placing a titanium sample in a calcium-phosphorus-sodium-silver electrolyte, and performing micro-arc oxidation to obtain a double-layer porous graded micro-arc oxidation coating; the calcium-phosphorus-sodium-silver electrolyte comprises sodium hexametaphosphate, silver nitrate, calcium acetate, calcium dihydrogen phosphate and distilled water;

in the calcium-phosphorus-sodium-silver electrolyte, the concentration of the sodium hexametaphosphate is 8-10 g/L, the concentration of the silver nitrate is 1-1.5 g/L, the concentration of the calcium acetate is 6.5-8.5 g/L, and the concentration of the calcium dihydrogen phosphate is 6.5-7.5 g/L;

the conditions of the micro-arc oxidation are as follows: the power supply is in a constant voltage mode, the forward voltage is 350-400V, the frequency is 450-500 Hz, and the duty ratio is 10-15%;

the time of the micro-arc oxidation is 10-15 min.

2. The method according to claim 1, wherein in the calcium-phosphorus-sodium-silver-based electrolyte, the concentration of sodium hexametaphosphate is 10g/L, the concentration of silver nitrate is 1g/L, the concentration of calcium acetate is 8.5g/L, and the concentration of calcium dihydrogen phosphate is 6.5g/L.

3. The method of claim 1, wherein the micro-arc oxidation takes the titanium sample as an anode and an electrolytic cell as a cathode; the material of the electrolytic tank comprises any one of stainless steel, carbon steel or nickel.

4. The method according to claim 1, wherein in the double-layer porous graded micro-arc oxidation coating, the pore diameter of the outer layer pores is 5 to 10 μm; the aperture of the inner layer hole is 200-1000 nm.

5. The method of claim 4, wherein in the double layer porous graded micro-arc oxidation coating, the outer layer pores have a pore size of 10 μm and the inner layer pores have a pore size of 400nm.

6. The method according to claim 1, wherein the surface of the titanium sample is polished and cleaned and then placed in the calcium-phosphorus-sodium-silver electrolyte.

7. The method of any one of claims 1-6, wherein the titanium sample comprises any one of pure titanium or a titanium alloy.

8. The method according to claim 1, wherein after the double-layer porous graded micro-arc oxidation coating is prepared, the micro-arc oxidation coating is cleaned and dried, and specifically comprises the following steps: and (3) flushing the micro-arc oxidation coating by distilled water, and drying in an electrothermal blowing drying oven.