阅读说明：本技术 一种具有抗细菌粘附的超疏水羟基磷灰石/硬脂酸复合涂层的制备方法 (Preparation method of super-hydrophobic hydroxyapatite/stearic acid composite coating with antibacterial adhesion ) 是由 蔡舒 李倩倩 解瑶 刘远 左佑 田梦 王重言 刘鹏博 于 2020-02-28 设计创作，主要内容包括：本发明涉及一种具有抗细菌粘附性的超疏水羟基磷灰石/硬脂酸复合涂层的制备方法。将镁合金表面在SiC砂纸上打磨,然后依次在丙酮、去离子水、无水乙醇中超声清洗后进行烘干；浸泡在NaOH溶液中进行碱热处理；将碱热处理后的样品放入盛有Ca<Sup>2+</Sup>、P<Sup>5+</Sup>混合溶液反应釜中,将反应釜放入110～130℃的烘箱中反应12～36h,反应后降温取出,依次用去离子水、无水乙醇超声清洗并烘干；再放入盛有硬脂酸乙醇溶液的回流容器中,于60～120℃采用回流法进行疏水处理1～3h,依次用去离子水、无水乙醇清洗并烘干后即得到超疏水羟基磷灰石/硬脂酸复合涂层包覆的镁合金。涂层是由纳米棒状组成的微米花状结构,制备工艺简单。(The invention relates to a preparation method of a super-hydrophobic hydroxyapatite/stearic acid composite coating with antibacterial adhesion. Polishing the surface of the magnesium alloy on SiC abrasive paper, then sequentially ultrasonically cleaning in acetone, deionized water and absolute ethyl alcohol, and then drying; soaking in NaOH solution for alkali heat treatment; putting the sample subjected to alkali heat treatment into the solution containing Ca 2+ 、P 5+ Putting the reaction kettle into a drying oven at 110-130 ℃ for reaction for 12-36 h in a mixed solution reaction kettle, cooling and taking out after the reaction, and carrying out ultrasonic cleaning and drying by using deionized water and absolute ethyl alcohol in sequence; then putting the mixture into a reflux container filled with stearic acid ethanol solution, and performing reflux at the temperature of between 60 and 120 ℃ by adopting a reflux methodAnd (3) carrying out hydrophobic treatment for 1-3 h, sequentially washing with deionized water and absolute ethyl alcohol, and drying to obtain the magnesium alloy coated with the super-hydrophobic hydroxyapatite/stearic acid composite coating. The coating is a micro flower-like structure consisting of nano rods, and the preparation process is simple.)

1. A preparation method of a super-hydrophobic hydroxyapatite/stearic acid composite coating with antibacterial adhesion is characterized by comprising the following steps:

(1) magnesium alloy surface polishing treatment: polishing the surface of the magnesium alloy on SiC abrasive paper, then sequentially ultrasonically cleaning in acetone, deionized water and absolute ethyl alcohol, and then drying;

(2) alkali heat treatment of the surface of the magnesium alloy: soaking the sample treated in the step (1) in a NaOH solution, carrying out water bath at 70-90 ℃ for 1-3 h, then washing with deionized water and absolute ethyl alcohol, and drying;

(3) preparing a micro/nano hydroxyapatite coating by a hydrothermal method: putting the sample subjected to alkali heat treatment in the step (2) into Ca^{2 +}、P⁵⁺Putting the reaction kettle into a drying oven with the temperature of 110-130 ℃ for reaction for 12-36 h in the reaction kettle for mixing the solution, cooling and taking out after the reaction, and carrying out ultrasonic cleaning and drying by using deionized water and absolute ethyl alcohol in sequence;

(4) hydrophobization treatment: and (4) putting the sample treated in the step (3) into a reflux container filled with a stearic acid ethanol solution, performing hydrophobic treatment for 1-3 h at the temperature of 60-120 ℃ by adopting a reflux method, sequentially cleaning with deionized water and absolute ethyl alcohol, and drying to obtain the magnesium alloy coated with the super-hydrophobic hydroxyapatite/stearic acid composite coating.

2. The method of claim 1, wherein the sandpaper roughness in step (1) is sequentially 800 mm^#，1200^#，1500^#，2000^#。

3. The method as set forth in claim 1, wherein the concentration of NaOH solution in the step (2) is 0.5 to 2 mol/L.

4. The method as set forth in claim 1, wherein Ca is selected in said step (3)²⁺、P⁵⁺The mixed solution is: EDTA2NaCa is used as Ca source, KH is used₂PO₄、(NH₄)₂HPO₄Or NaH₂PO₄Adding Ca source into deionized water for magnetic stirring as P source, completely dissolving, and adding P sourceStirring by magnetic force until the solution is completely dissolved; and then adjusting the pH value of the mixed solution to 7-10 by using an alkaline NaOH solution, and magnetically stirring for 1-3 h.

5. The method as set forth in claim 4, wherein Ca is contained in the mixed solution²⁺The concentration of (A) is 0.1-0.3 mol/L, P⁵⁺The concentration of the NaOH solution is 0.1-0.3 mol/L, wherein the concentration of the NaOH solution for adjusting the pH value is 1-4 mol/L.

6. The method as set forth in claim 1, wherein the reaction in the step (3) is carried out in an oven at 110-130 ℃ for 12-36 hours.

7. The method as set forth in claim 1, wherein the material of the inner liner of the reaction vessel in the step (3) is polytetrafluoroethylene.

8. The method as set forth in claim 1, wherein the concentration of the ethanol stearate in the step (4) is 0.05-0.2 mol/L, and the reflux is carried out at 60-120 ℃ for 1-3 h.

Technical Field

The invention relates to a preparation method of a super-hydrophobic hydroxyapatite/stearic acid composite coating with antibacterial adhesion on the surface of a magnesium alloy, belonging to the technical field of surface modification of degradable magnesium alloy implants.

Background

The magnesium alloy has smaller specific strength, the elastic modulus and the yield strength of the magnesium alloy are closest to those of human bones, and the magnesium alloy has good biocompatibility and mechanical compatibility; magnesium is used as an essential element of human body, has no toxicity to human body, plays an important role in regulating bone mineral metabolism and protein synthesis, and has rich magnesium resource reserves and low cost. Magnesium alloy becomes a new generation biomedical implant material by virtue of good comprehensive mechanical property, biocompatibility and biodegradability, but magnesium alloy is easy to corrode in body fluid, and the development of the magnesium alloy in the field is greatly restricted.

The hydroxyapatite has excellent biocompatibility and good chemical stability and becomes a preferred material for surface modification of medical implanted magnesium alloy. The hydroxyapatite is coated on the surface of the magnesium alloy, thereby not only relieving the degradation of the magnesium alloy, but also enhancing the osseointegration capability of the implant and ensuring the early stability of the implant. Chinese patent (CN 109758605A) reports that a micro-nano needle-shaped hydroxyapatite coating is prepared on the surface of a magnesium alloy through electrochemical deposition, and the coating is uniform and compact and is beneficial to the adhesion and growth of cells on the surface of the coating. Chinese patent (CN 108004527A) reports that a zinc-doped modified hydroxyapatite coating is prepared on the surface of a magnesium alloy by a hydrothermal method, and the coating has a nano flower-like structure, is uniform and compact, and effectively improves the corrosion resistance and biocompatibility of the magnesium alloy. However, in addition to the need for good osseointegration of the implant with the surrounding tissue, potential bacterial infection is considered to be one of the most serious postoperative complications. Infection may lead to delayed healing and failure of the implant. In the early stages of implantation (4-6h), bacteria may adhere to the implant surface through physicochemical interactions, and the host's immune response does not completely eliminate the bacteria adhering at the bone-implant interface, and after 6h, the bacteria will irreversibly adhere to the implant and rapidly grow and multiply to form a biofilm, enabling the bacteria to resist host defense and antimicrobial therapy, resulting in continued infection of the implant. Therefore, the development of an antibacterial implant that can inhibit bacterial adhesion at an early stage is crucial to its long-term survival. Related patents include: in Chinese patent (CN110115777A), a hydroxyapatite coating is prepared on the surface of a titanium alloy by a hydrothermal method, and then bacteriostatic treatment is carried out in an antibiotic solution to obtain a titanium alloy material with a coating with good biocompatibility and bacteriostatic function; the silver-doped hydroxyapatite composite coating is prepared on the surface of the titanium alloy by a vacuum plasma spraying process in Chinese patent (CN 101070441A), and the coating has excellent antibacterial effect. The above reported antibacterial coatings all have significant antibacterial effects, but still have disadvantages, such as: excessive use of antibiotics can cause bacteria to develop drug resistance, resulting in antibiotic failure; the doping of silver in the antibacterial coating complicates the operation, and the sterilization mechanism of nano silver still remains a big debate.

Due to the good moisture resistance, the super-hydrophobic material has a plurality of special functions, such as: corrosion resistance, self-cleaning, anti-bacterial adhesion and freeze resistance. Due to the micro-nano hierarchical rough structure and the low surface energy of the surface of the super-hydrophobic coating, an air layer is formed between the hydrophobic surface and the corrosive solution, so that the bacterium adhesion of the super-hydrophobic surface is effectively reduced, the surface bacteria are easily removed, and the leather is preventedThe adhesion of gram-negative bacteria and gram-positive bacteria can avoid the formation of a biological film on the surface of the material in a certain period of time, and the super-hydrophobic coating can also obviously improve the corrosion resistance of the matrix. Zhongwei Wang et al (research a high purity refractory reinforced onAZ91D magnesium alloy and its anti-bacterial additive effect. materials characterization. criteria. characteristics. characterization.2015.1) reported that a sheet-like structure magnesium hydroxide coating was prepared on a magnesium alloy substrate by a one-step hydrothermal method, and a superhydrophobic coating was formed after a hydrophobic treatment, which prevents adhesion of bacteria on the magnesium alloy and significantly improves corrosion resistance of the magnesium alloy. The invention utilizes the good biocompatibility of hydroxyapatite and the antibacterial adhesion performance of a super-hydrophobic material to prepare the super-hydrophobic hydroxyapatite/stearic acid composite coating with a micro/nano hierarchical coarse structure on the magnesium alloy by a hydrothermal method. The coating is formed by physically combining hydroxyapatite with stearic acid, and the stearic acid is a saturated acid in a human body and has no biotoxicity. The coating utilizes the micro/nano hierarchical coarse structure of the hydroxyapatite coating and the low surface functional group-CH in stearic acid molecules₂-and-CH₃(31 mJ/m, respectively)²And 24mJ/m²) The super-hydrophobic coating suitable for a Cassie-Baxter wetting model is formed, the solid-liquid contact area is reduced, and the antibacterial adhesion and corrosion resistance of the magnesium alloy at the initial implantation stage are improved. On the other hand, as the stearic acid on the surface of the coating is degraded, the micro/nano graded hydroxyapatite coating is exposed in body fluid, and the larger specific surface area rapidly induces the deposition of mineralized substances, thereby promoting the cell adhesion, proliferation and differentiation. Until now, few researches and patents are provided for preparing a superhydrophobic hydroxyapatite/stearic acid composite coating with a micro-nano structure by a hydrothermal method, and particularly, no report is provided for researches on the application of the superhydrophobic hydroxyapatite/stearic acid composite coating with the micro-nano structure to the antibacterial adhesion of a medical implant.

Disclosure of Invention

In view of the above-mentioned problems with medical implant materials, it is an object of the present invention to provide a bioactive coating having good corrosion resistance and anti-bacterial adhesion properties. The invention adopts a simple hydrothermal method to prepare the hydroxyapatite coating with micro/nano grading flower-shaped structure on the magnesium alloy, and then reduces the surface energy of the hydroxyapatite coating by stearic acid treatment to form the super-hydrophobic hydroxyapatite/stearic acid composite coating (the preparation process is shown in figure 1). The surface appearance is observed through scanning of an electron microscope, and the coating is found to be composed of a uniform and compact micro/nano hierarchical flower-shaped structure, and the surface appearance is not changed before and after hydrophobic treatment. An air layer can be stored between the micro/nano rough flower-shaped structures, the contact area between the surface of the material and body fluid is reduced, the corrosion of the inside of the coating by solution is effectively inhibited, the adhesion of bacteria on the surface of the magnesium alloy is reduced, and the corrosion resistance of the magnesium alloy is improved. Compared with the prior preparation technology of the antibacterial adhesion surface, the preparation method provided by the invention has the advantages that the antibacterial adhesion performance of the magnesium alloy is enhanced, and the corrosion resistance and the biological activity of the magnesium alloy are improved. And the implementation process has simple conditions and convenient and easy operation.

The purpose can be realized by the following technical scheme:

a preparation method of a super-hydrophobic hydroxyapatite/stearic acid composite coating with antibacterial adhesion performance comprises the following steps:

(1) magnesium alloy surface polishing treatment: polishing the surface of the magnesium alloy on SiC abrasive paper, then sequentially ultrasonically cleaning in acetone, deionized water and absolute ethyl alcohol, and then drying;

(2) alkali heat treatment of the surface of the magnesium alloy: soaking the sample treated in the step (1) in a NaOH solution, carrying out water bath at 70-90 ℃ for 1-3 h, then washing with deionized water and absolute ethyl alcohol, and drying;

(3) preparing a micro/nano hydroxyapatite coating by a hydrothermal method: putting the sample subjected to alkali heat treatment in the step (2) into Ca²⁺、P⁵⁺Putting the reaction kettle into a drying oven with the temperature of 110-130 ℃ for reaction for 12-36 h in the reaction kettle for mixing the solution, cooling and taking out after the reaction, and carrying out ultrasonic cleaning and drying by using deionized water and absolute ethyl alcohol in sequence;

(4) hydrophobization treatment: and (4) putting the sample treated in the step (3) into a reflux container filled with a stearic acid ethanol solution, performing hydrophobic treatment for 1-3 h at the temperature of 60-120 ℃ by adopting a reflux method, sequentially cleaning with deionized water and absolute ethyl alcohol, and drying to obtain the magnesium alloy coated with the super-hydrophobic hydroxyapatite/stearic acid composite coating.

The roughness of the sand paper in the step (1) is 800 in sequence^#，1200^#，1500^#，2000^#。

The concentration of the NaOH solution in the step (2) is 0.5-2 mol/L.

Ca is preferable in the step (3)²⁺、P⁵⁺The mixed solution is: EDTA2NaCa is used as Ca source, KH is used₂PO₄、(NH₄)₂HPO₄Or NaH₂PO₄Adding a Ca source into deionized water for magnetic stirring to serve as a P source, and adding the P source for magnetic stirring after complete dissolution until complete dissolution; then, adjusting the pH value of the mixed solution to 7-10 by using an alkaline NaOH solution, and magnetically stirring for 1-3 h; wherein, Ca is contained in the mixed solution²⁺The concentration of (A) is 0.1-0.3 mol/L, P⁵⁺The concentration of the NaOH solution is 0.1-0.3 mol/L, wherein the concentration of the NaOH solution for adjusting the pH value is 1-4 mol/L.

In the step (3), the reaction is preferably carried out in an oven at 110-130 ℃ for 12-36 h.

And (4) the lining of the reaction kettle in the step (3) is made of polytetrafluoroethylene.

In the step (4), the concentration of the stearic acid ethanol is 0.05-0.2 mol/L, and the stearic acid ethanol is subjected to heat preservation and reflux for 1-3 hours at the temperature of 60-120 ℃.

Compared with the prior art, the invention has the following beneficial effects:

1. when the antibacterial adhesive super-hydrophobic hydroxyapatite/stearic acid composite coating prepared on the magnesium alloy by adopting the method is observed under the scanning of an electron microscope, the surface appearance of the coating is uniform and compact, and the coating is a micrometer flower-shaped coarse structure consisting of nano rods. Therefore, the coating has a micro-nano hierarchical coarse structure and low surface energy, provides necessary conditions for preparing the super-hydrophobic coating, and utilizes a contact angle measuring instrument to measure that the static contact angle reaches 152 degrees and the rolling angle is 2 degrees.

2. Compared with the existing antibacterial material, the magnesium alloy coated by the antibacterial super-hydrophobic hydroxyapatite/stearic acid composite coating can resist the adhesion of gram-negative bacteria and gram-positive bacteria simultaneously through bacterial experiments, can prevent the bacteria from generating drug resistance, and ensures the stable existence of the implant in the organism due to good biocompatibility.

3. The super-hydrophobic hydroxyapatite/stearic acid composite coating prepared by the invention enables an air layer to exist between the matrix and the solution, and the air layer effectively shields the invasion of corrosive ions. The alternating current impedance of the material reaches 301kohm cm by electrochemical test²The corrosion current density reaches 1.64 × 10^-7A/cm²And has good corrosion resistance.

4. The method has high repeatability and simple experimental process equipment, and can prepare the super-hydrophobic hydroxyapatite/stearic acid composite coating on the surface of the magnesium alloy sample with any shape and size.

Drawings

FIG. 1 is an experimental flow chart of preparing a superhydrophobic hydroxyapatite/stearic acid composite coating on a magnesium alloy;

FIG. 2 is a SEM photograph of the surface morphology of the super-hydrophobic hydroxyapatite/stearic acid composite coating prepared in example 1 of the present invention;

fig. 3 is a contact angle photograph of the superhydrophobic hydroxyapatite/stearic acid composite coating prepared in example 1 of the present invention;

FIG. 4 is a photograph of the contact angle of the hydroxyapatite coating layer prepared in example 1 of the present invention;

FIG. 5 is a photograph showing the contact angle of bare magnesium alloy in example 1 of the present invention;

fig. 6 is an alternating current impedance spectrum of the magnesium alloy coated with the superhydrophobic hydroxyapatite/stearic acid composite coating, the magnesium alloy coated with the hydroxyapatite coating, and the bare magnesium alloy in a simulated body fluid, which are prepared in example 1 of the present invention;

FIG. 7 is an electron microscope scanning image of the magnesium alloy coated with the superhydrophobic hydroxyapatite/stearic acid composite coating prepared in example 1 of the present invention cultured in Escherichia coli for 8 h;

FIG. 8 is an electron microscope scanning image of the magnesium alloy coated with hydroxyapatite coating prepared in example 1 of the present invention cultured in Escherichia coli for 8 h;

FIG. 9 is an electron microscope scan of the naked magnesium alloy cultured in Escherichia coli for 8h according to example 1 of the present invention;

fig. 10 shows fourier infrared (FT-IR) spectra of the superhydrophobic hydroxyapatite/stearic acid composite coating, the hydroxyapatite coating, and the bare magnesium alloy prepared in example 2 of the present invention.

Detailed Description

The invention is further illustrated and described with reference to the following examples, which are not intended to limit the invention in any way. The starting materials used in the following examples are all commercially available analytical pure materials.