A magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating and a preparation method thereof

Abstract

The present invention discloses a magnesium alloy vascular stent material with a nano-water-repellent layer and a bioactive coating and a preparation method thereof, belonging to the field of surface treatment of vascular stent materials. A nano-water-repellent intermediate layer is constructed by introducing thiol-containing hydrophobic molecules on the surface of the pretreated magnesium alloy vascular stent material, which is mainly to solve the problem of fast degradation rate faced by the current magnesium alloy vascular stent. The surface of the nano-water-repellent layer is modified with a bioactive coating to further improve the biological properties of the magnesium alloy vascular stent. The method of the present invention has mild reaction conditions, low cost, and is conducive to post-processing. The developed nano-water-repellent intermediate layer has good hydrophobicity and can significantly delay the penetration of water molecules in the physiological environment, thereby reducing the degradation rate of the magnesium alloy vascular stent material and extending the service time in the body without reducing the biocompatibility of the magnesium alloy vascular stent; the present invention has strong operability and significant effect, and provides a new method for surface modification of magnesium alloy vascular stent materials.

Description

Technical Field

[0001] The invention belongs to the field of surface treatment of magnesium alloy vascular stent materials, and particularly relates to a magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating and a preparation method thereof. Background Art

[0002] Cardiovascular disease has become one of the diseases with the highest morbidity and mortality rates worldwide. In recent decades, metal vascular stent implantation has become the main clinical interventional treatment for stenotic cardiovascular disease due to its advantages of minimal trauma, rapid recovery, and low economic burden. However, the non-degradable stents currently used in clinical practice remain permanently in the body after implantation, which will inevitably cause complications such as inflammation, intimal hyperplasia, and late thrombosis. Magnesium alloys have good biocompatibility and biodegradability, and have great application potential in the field of degradable vascular stent materials. They are currently a research hotspot for cardiovascular stent materials. However, the rapid degradation of magnesium alloys in physiological environments causes many adverse reactions, such as magnesium ion enrichment, local alkalinization, and secondary corrosion products, which lead to the initial loss of radial support of the stent, thereby causing implant failure.

[0003] Surface treatment is an effective strategy to slow down the degradation rate of magnesium alloys. Fluoridation is a technique for preparing a fluoridated film on a magnesium substrate. Sun et al. found that the magnesium fluoride protective layer formed by fluoridation significantly inhibited the degradation rate of magnesium alloy vascular stent materials, but the cell compatibility of the fluoridated layer was poor [Progress in Organic Coatings 187(2024) 108177]. In a previous study, our team induced the formation of a polythioate copper precursor solution in an ethanol solution and then prepared it on the surface of a fluoridated magnesium alloy vascular stent. The corrosion current density of the magnesium fluoride-polythioate copper coating sample was 9.16×10 -8 A / cm 2 , with good adhesion (~603 mN) and biocompatibility, and superior endothelialization compared to drug-eluting coatings [ZL202211508122.2]. In subsequent studies, animal implantation experiments demonstrated that magnesium fluoride-copper polylipoate-coated stents exhibited excellent anti-proliferative and rapid endothelialization effects. However, magnesium fluoride-copper polylipoate coatings still present certain challenges. Firstly, the implantation of the coated stent requires a compression-grip expansion process, and the adhesion of the coating needs to be further improved. Secondly, the volume of the coated stent degraded by approximately 38.5% six months after implantation. Although the magnesium fluoride-copper polylipoate-coated stent provides sufficient radial support during revascularization, the degradation rate still needs to be further slowed to avoid late restenosis. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide a magnesium alloy vascular stent material with a nano-water-repellent layer and a bioactive coating and a preparation method thereof. The preparation cost is low, the intermediate layer has good hydrophobicity, and can significantly reduce the degradation rate of the magnesium alloy vascular stent material, prolonging its service life in the body without reducing the biocompatibility of the magnesium alloy vascular stent, thereby having good biocompatibility. The surface of the nano-water-repellent layer can also be subsequently modified with a lipoic acid-based bioactive coating to further improve the biological performance of the magnesium alloy vascular stent.

[0005] Based on the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating comprises the following steps:

[0007] (1) Take the magnesium alloy vascular stent material, polish it with sandpaper until the surface is flat and smooth, rinse it with deionized water and anhydrous ethanol in sequence, dry it, and set aside;

[0008] (2) fluoriding the magnesium alloy vascular stent material of step (1) to obtain a sample having a magnesium fluoride layer on the surface;

[0009] The specific process is as follows: immerse the magnesium alloy vascular stent material in step (1) in a hydrofluoric acid solution with a concentration of 35-40 wt%, react at room temperature for 12-48 h, clean it, and dry it to obtain a magnesium fluoride coating sample;

[0010] (3) depositing polydopamine on the surface of the sample in step (2);

[0011] The specific process is as follows: prepare a tris(hydroxymethyl)aminomethane aqueous solution with a concentration of 10-20 mmol / L, add hydrochloric acid to adjust the pH to 8.5-9.0, then add dopamine hydrochloride to make the concentration of dopamine hydrochloride 2-4 mg / mL, seal and stir for 20-40 minutes, soak the sample in step (2) in the above solution for 12-48 hours, shake at a speed of 40-100 rpm, and at a reaction temperature of 20°C-40°C, wash with deionized water, and dry to obtain a polydopamine layer sample;

[0012] (4) dissolving the thiol-containing hydrophobic molecule in an alcohol solvent at a concentration of 1.0-5.0‰ (V / V) to obtain a hydrophobic molecule solution, placing the magnesium alloy vascular stent material obtained in step (3) in the hydrophobic molecule solution, reacting for 6-24 hours at a temperature of 40°C-60°C, then rinsing with anhydrous ethanol and drying to obtain the product;

[0013] (5) Dissolve lipoic acid in an organic solvent at a concentration of 0.1 g / mL to 0.5 g / mL, add an inorganic salt, and stir until completely dissolved to obtain a lipoic acid-based precursor solution, which is then prepared on the surface of a vascular stent material containing a nano-water-repellent layer and dried to obtain a bioactive coating on the surface of the nano-water-repellent layer.

[0014] Preferably, the magnesium alloy vascular stent material in step (1) is ZE21B, WE43, AZ31 or AZ91.

[0015] Preferably, the concentration of hydrochloric acid in step (1) is 0.5-2 mol / L.

[0016] Preferably, the thiol-containing hydrophobic molecule in step (4) is perfluorodecyl mercaptan, perfluorooctyl mercaptan, perfluorohexyl mercaptan, n-octadecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan or n-dodecyl mercaptan.

[0017] Preferably, the inorganic salt in step (5) is zinc chloride, zinc sulfate, ferric chloride, ferric sulfate, copper chloride or copper sulfate.

[0018] Preferably, the organic solvent in step (5) is N,N-dimethylformamide, dichloromethane, isopropanol, anhydrous methanol or anhydrous ethanol.

[0019] Preferably, the lipoic acid-based coating in step (5) is prepared by dip coating, spin coating or spray coating.

[0020] Preferably, the drying in steps (1) to (5) is carried out at 40°C to 60°C for 5 to 30 minutes.

[0021] The magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating is prepared by the preparation method.

[0022] The thickness of the magnesium fluoride layer is 0.8 μm~3.0 μm, the thickness of the polydopamine layer is 0.5 μm~2.0 μm, the thickness of the nano-water-repellent layer is 100 nm~150 nm, and the thickness of the bioactive coating is 1.0 μm~6.0 μm.

[0023] The application of the magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating in the preparation of in vivo implants.

[0024] The above technical solution directly benefits from low cost and simple operation. The developed nano-hydrophobic interlayer exhibits excellent hydrophobicity, significantly slowing the penetration of water molecules in physiological environments. This reduces the degradation rate of the magnesium alloy vascular stent material and prolongs its in vivo service life without compromising the biocompatibility of the magnesium alloy vascular stent. The surface of the nano-hydrophobic interlayer can also be subsequently modified with a lipoic acid-based bioactive coating to further improve the biological performance of the magnesium alloy vascular stent. The method of the present invention is highly operational and effective, providing a new approach for surface coating of magnesium alloy vascular stent materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the preparation of the magnesium fluoride / polydopamine / perfluorodecylmercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in Example 1;

[0026] Figure 2 SEM images of the magnesium fluoride layer prepared in the second step of Example 1, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in the fifth step;

[0027] Figure 3 EDS data graphs of the magnesium fluoride layer prepared in the second step of Example 1, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in the fifth step;

[0028] Figure 4 FT-IR images of the magnesium fluoride layer prepared in the second step of Example 1, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in the fifth step;

[0029] Figure 5 Nanoscratch images of the magnesium fluoride layer prepared in the second step of Example 1, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in the fifth step;

[0030] Figure 6These are water contact angle graphs of the magnesium fluoride layer prepared in the second step of Example 1, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in the fifth step;

[0031] Figure 7 Middle: (a) Figure shows the potentiodynamic polarization curves of the magnesium fluoride layer prepared in the second step of Example 1, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / thioctic acid-Cu(II) coating prepared in the fifth step; (b) Figure shows the potentiodynamic polarization curves of the ZE21B magnesium alloy / polydopamine layer and the ZE21B magnesium alloy / thioctic acid-Cu(II) coating;

[0032] Figure 8 This is a graph showing the endothelial cell survival rate of the magnesium alloy prepared in the first step of Example 1, the magnesium fluoride layer prepared in the second step, the magnesium fluoride / polydopamine layer prepared in the third step, the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer prepared in the fourth step, and the magnesium fluoride / polydopamine layer / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating prepared in the fifth step;

[0033] Figure 9 These are water contact angle diagrams of the magnesium fluoride / polydopamine / n-dodecylmercaptan water-repellent layer prepared in the fourth step of Example 2 and the magnesium fluoride / polydopamine / n-dodecylmercaptan water-repellent layer / lipoic acid-Fe(III) coating prepared in the fifth step. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below with reference to examples, but the protection scope of the present invention is not limited thereto.

[0035] The magnesium alloy vascular stent material used in the present invention can be purchased through the Materials Research Center of Zhengzhou University or commercial channels.

[0036] Example 1:

[0037] A method for preparing a magnesium alloy vascular stent material with a perfluorodecyl mercaptan nano-water-repellent layer and a thioctic acid-Cu(II) coating (bioactive coating), such as Figure 1 As shown, the following steps are included:

[0038] The magnesium alloy vascular stent is made of Mg-2.0Zn-0.5Y-0.5Nd magnesium alloy (brand ZE21B, for the specific preparation process, please refer to patent CN201110043303.8).

[0039] Step 1: Pretreatment of magnesium alloy

[0040] The magnesium alloy was cut into cylinders with a diameter of 10 mm and a thickness of 3 mm. The surfaces were polished with 100-mesh, 400-mesh, 800-mesh, and 1000-mesh sandpapers in sequence until the surfaces were smooth and flat. The surfaces were then rinsed with deionized water and anhydrous ethanol in sequence, dried at 50°C for 10 min, and set aside.

[0041] Step 2: Surface fluorination treatment of magnesium alloy

[0042] The polished ZE21B magnesium alloy sheet was placed in a 24-well plate (about 1.5 cm in diameter, about 2 cm in depth, and capable of holding about 3.3 mL of solution).

[0043] Add 2 mL of 40 wt% hydrofluoric acid solution to the wells containing the magnesium alloy sheets, place the 24-well plate in a fume hood, and leave it at room temperature for 12 h;

[0044] The fluorinated ZE21B magnesium alloy sheet was taken out, rinsed with deionized water and anhydrous ethanol in sequence to remove residual hydrofluoric acid, dried at 50°C for 10 min, and set aside.

[0045] Step 3: Polydopamine deposition treatment

[0046] A 10 mM tris(hydroxymethylaminomethane) aqueous solution was prepared, and a 0.5 mol / L dilute hydrochloric acid solution was added dropwise to adjust the pH to 8.5 to obtain a tris(hydroxymethylaminomethane)-hydrochloric acid solution;

[0047] Dissolve dopamine hydrochloride in the above-mentioned tris(hydroxymethylaminomethane)-hydrochloric acid solution to a concentration of 2.0 mg / mL, seal and stir for 30 minutes to obtain a dopamine solution;

[0048] The fluorinated ZE21B magnesium alloy sample was placed in a 24-well plate, 1.5 mL of the above-mentioned dopamine solution was added to each well, and the plate was fixed on a constant temperature shaker at 60 rpm and deposited at 25°C for 12 h.

[0049] The polydopamine-treated sample was taken out, rinsed with deionized water and anhydrous ethanol in sequence, dried at 50°C for 10 min, and set aside.

[0050] Step 4: Preparation of perfluorodecyl mercaptan nano-water repellent layer

[0051] Prepare a 1.5‰ (V / V) perfluorodecyl mercaptan ethanol solution, place the polydopamine coating sample in a 50 mL beaker, add 30 mL of the perfluorodecyl mercaptan ethanol solution, react at 60°C for 12 h, wash with ethanol three times, and dry at 50°C for 10 min.

[0052] Step 5: Preparation of lipoic acid-Cu(Ⅱ) coating

[0053] A 0.15 g / mL lipoic acid solution was prepared using anhydrous ethanol as the solvent, followed by the addition of copper chloride at a molar ratio of copper chloride to lipoic acid of 1:1000 to obtain a lipoic acid-Cu(II) solution.

[0054] The magnesium alloy material containing the perfluorodecyl mercaptan nano-water-repellent layer was immersed in the above-mentioned thioctic acid-Cu(II) solution for 1 s, taken out, and then placed in an oven and dried at 50°C for 30 min to obtain the magnesium alloy material.

[0055] The prepared magnesium alloy sample modified with magnesium fluoride / polydopamine / perfluorodecyl mercaptan water-repellent layer / lipoic acid-Cu(II) coating was placed in a sample bag and sealed for later use.

[0056] Preparation of magnesium alloy / polydopamine layer

[0057] The ZE21B magnesium alloy sample after the first step pretreatment was placed in a 24-well plate, and 1.5 mL of the 2.0 mg / mL dopamine solution prepared in the third step of Example 1 was added to each well. The well plate was fixed on a constant temperature shaker at a speed of 60 rpm and deposited at 25°C for 12 h. The polydopamine-treated sample was removed, rinsed with deionized water and anhydrous ethanol in sequence, and dried at 50°C for 10 min.

[0058] Preparation of Magnesium Alloy / Lipoic Acid-Cu(Ⅱ) Coating

[0059] A 0.15 g / mL lipoic acid solution was prepared using anhydrous ethanol as the solvent, followed by the addition of copper chloride at a molar ratio of copper chloride to lipoic acid of 1:1000 to obtain a lipoic acid-Cu(II) solution.

[0060] The magnesium alloy sample after the first step pretreatment was immersed in the above-mentioned thioctic acid-Cu (II) solution for 1 s, taken out, and then placed in an oven and dried at 50°C for 30 min.

[0061] The thioctic acid-Cu(II) coating sample with a perfluorodecylmercaptan water-repellent layer embedded on the surface of the ZE21B magnesium alloy prepared in Example 1 was subjected to scanning electron microscopy (SEM) observation, energy dispersive spectroscopy (EDS) analysis, Fourier transform infrared spectroscopy (FT-IR) analysis, nanoscratch test, water contact angle test, AC impedance spectroscopy analysis, and endothelial cell AO / EB test. The preparation process is as follows Figure 1 The experimental results are shown in Figure 2-Figure 8 shown.

[0062] Figure 1This is a diagram of the preparation mechanism of the magnesium fluoride / polydopamine / perfluorodecyl mercaptan water-repellent layer / thioctic acid-Cu(II) coating prepared in Example 1. Perfluorodecyl mercaptan can be grafted onto the surface of polydopamine molecules by Michael addition to form a nano-water-repellent layer, and then the thioctic acid-Cu(II) coating is prepared by the immersion and pulling method.

[0063] Figure 2 The SEM images of each layer prepared in Example 1 are gold-sprayed before observing the morphology. Figure 2 The surface of the magnesium fluoride-coated sample is flat and smooth. After polydopamine treatment, the surface displays a dense nanoscale particle morphology. After surface grafting with perfluorodecylmercaptan, the perfluorodecylmercaptan water-repellent layer exhibits a morphology similar to that of the polydopamine-coated sample. The surface nanoscale water-repellent layer is very thin and does not alter the polydopamine coating morphology. After coating with lipoic acid-Cu(II) coating, the surface morphology of the magnesium alloy vascular stent material is uniform.

[0064] Figure 3 The EDS data of each layer prepared in Example 1 are shown. The elemental composition of the magnesium fluoride coating sample is mainly Mg and F, corresponding to magnesium fluoride. After the polydopamine layer is deposited, the main elements are C, N and O. After the surface is grafted with perfluorodecyl mercaptan, the proportion of F and C elements increases significantly, indicating that the perfluorodecyl mercaptan molecules are successfully fixed to the surface of the polydopamine layer. The elemental composition of the lipoic acid-Cu(Ⅱ) coating is mainly S, O and C. Due to the low content of Cu, the presence of Cu was not detected.

[0065] Figure 4 FT-IR spectra of each layer prepared in Example 1. Figure 4 As shown. No chemical bonds were detected on the surface of the magnesium fluoride layer sample. After the polydopamine layer was deposited, the -1 and 1410 cm -1 The absorption peak at 1490 cm is attributed to the stretching vibration peak of the C=C bond in the aromatic ring. -1 The peak at 1100-1300 cm corresponds to the shear vibration peak of the NH bond in the polydopamine molecule. -1 The lipoic acid-Cu(Ⅱ) coating showed some obvious absorption peaks in the range of 1706 cm-1, which was attributed to the vibration of the CF bond in the perfluorodecyl mercaptan molecule. -1 ) is due to the C=O stretching vibration peak of a part of -COOH coordinated with Cu(Ⅱ), which enhances the C=O stretching, 1615 cm -1 The peak at confirms the formation of a coordination bond between Cu (II) and -COOH.

[0066] Figure 5The nanoscratch test of each layer prepared in Example 1 was performed at a constant moving rate (2 mm / min) by increasing the linear load to 5 N at a loading rate of 5 N / min until the scratch distance reached 2 mm. Figure 5 As shown, the critical load of the perfluorodecylthiol water-repellent layer sample was 570 mN, indicating good adhesion. After further modification, the adhesion of the lipoic acid-Cu(II) coating reached 860 mN. This is attributed to the fact that the perfluorodecylthiol water-repellent layer can provide abundant F elements, which can form tight hydrogen bonds with -COOH, thereby improving the adhesion of the outer lipoic acid-Cu(II) coating. This is significantly better than the adhesion of the previously reported magnesium fluoride-polythioate copper coating sample (~603 mN) [ZL202211508122.2]. Furthermore, nanoscratch testing can also reflect the thickness of the coating to a certain extent. It was found that the thicknesses of the magnesium fluoride layer, polydopamine layer, perfluorodecylthiol water-repellent layer, and lipoic acid-Cu(II) coating were approximately 910 nm, 740 nm, 130 nm, and 5360 nm, respectively.

[0067] Figure 6 This is a water contact angle experiment of each layer prepared in Example 1. The water contact angle of the magnesium fluoride layer sample is 10.3°. This is because the presence of the dense and hydrophilic fluorinated layer significantly improves the hydrophilicity of the sample. The hydrophilicity of the polydopamine layer surface decreases, and its contact angle increases to 57.7°. After perfluorodecyl mercaptan is fixed on the surface, the water contact angle of the nano-water-repellent layer is 90.2°, which significantly delays the diffusion and penetration of water molecules. After further modification of the lipoic acid-Cu(Ⅱ) coating, the surface contact angle drops to 84.8°. The surface of the biomaterial with moderate hydrophilicity can promote cell growth and improve biocompatibility.

[0068] The electrochemical corrosion behavior of the magnesium fluoride / polydopamine / perfluorodecylmercaptan water-repellent layer / lipoic acid-Cu(II) coating sample was studied using an electrochemical workstation. The specific test steps are as follows: The relevant electrochemical tests were performed using an electrochemical workstation. The electrolyte was Hank's balanced salt solution at 37°C. All electrochemical measurements were performed in a traditional three-electrode system, in which a platinum sheet was used as the counter electrode, a saturated calomel electrode was used as the reference electrode, and an exposed area of ​​0.78 cm was used. 2 The sample was used as the working electrode. The sample was immersed in Hanks' solution and allowed to stand for 1200 s to allow the open circuit potential to reach a stable state. −1 The potentiodynamic polarization curve of the sample from -2.0 V to 0.0 V was recorded at a constant scan rate, and the corresponding corrosion current density was obtained by Tafel extrapolation. Generally speaking, the lower the corrosion current density, the slower the degradation rate. Figure 7The potentiodynamic polarization curves of each sample are shown. The corrosion current density of the magnesium fluoride / polydopamine / perfluorodecylmercaptan water-repellent layer / lipoic acid-Cu(Ⅱ) coating is 2.56 × 10 -8 A / cm 2 , indicating a lower degradation rate, significantly delaying the diffusion and penetration of water molecules. The degradation rate is significantly lower than that of previous studies: the corrosion current density of the magnesium fluoride-polythioate copper coating sample is 9.16×10 -8 A / cm 2 [ZL202211508122.2]. In addition, with ZE21B magnesium alloy / polydopamine layer (6.28×10 -6 A / cm 2 ) and ZE21B magnesium alloy / thioctic acid-Cu(Ⅱ) coating (4.20 ×10 -5 A / cm 2 ), the corrosion current density of the current magnesium fluoride / polydopamine / perfluorodecylmercaptan water-repellent layer / lipoic acid-Cu(Ⅱ) coating system is about 2 to 3 orders of magnitude lower.

[0069] Endothelial cells were cultured at 4 × 10 3 The cells were seeded at a concentration of 5 μL cells / well onto the bottom of a 24-well plate adhered to the substrate. 400 μL of endothelial cell culture medium was added to each well and cultured in a constant temperature incubator at 37°C and 5% CO2 for 24 h. The waste liquid was then removed, and 200 μL of culture medium and sample extract were added to each well at a ratio of 1:1. 20 μL of fetal bovine serum and 2 μL of penicillin-streptomycin solution were added. This step was repeated every 24 h to replace the fresh culture medium. 5 μL of acridine orange (AO) and ethidium bromide (EB) stains were added to the sample in sequence and stained for 5 min in the dark. The samples were observed and photographed under an inverted fluorescence microscope. Five images were selected for each group of samples, and the number of living cells and apoptotic cells in each image was calculated. The survival rate of endothelial cells was calculated according to Formula 1:

[0070] Survival rate (%) = surviving cells / (surviving cells + apoptotic cells) × 100% (1)

[0071] like Figure 8As shown, throughout the culture period, the ZE21B magnesium alloy sample group had the lowest endothelial cell survival rate, at 93.8 ± 0.87% (1 day) and 94.5 ± 1.98% (3 days), indicating that the magnesium alloy promotes endothelial cell apoptosis. The MgF layer group showed a slight increase in endothelial cell survival rate, reaching 95.5 ± 0.49% (1 day) and 97.3 ± 0.16% (3 days), but still caused endothelial cell apoptosis. After modification with a polydopamine layer, the endothelial cell survival rate of the sample group was significantly improved, reaching 97.7 ± 0.44% (1 day) and 98.1 ± 0.38% (3 days), significantly promoting endothelial cell survival. After surface modification with a perfluorodecylthiol nano-water-repellent layer, endothelial cell survival rates were 97.8 ± 0.28% (1 day) and 98.1 ± 0.60% (3 days), without compromising the biocompatibility of the polydopamine layer. For the lipoic acid-Cu(Ⅱ) coating, without the addition of an NO donor, endothelial cell survival rates were 98.08 ± 0.99% (1 day) and 99.14 ± 0.02% (3 days), demonstrating good endothelial cell compatibility. The introduction of an NO donor further increased the endothelial cell survival rates of the lipoic acid-Cu(Ⅱ) coating to 99.09 ± 0.14% (1 day) and 99.83 ± 0.01% (3 days), significantly promoting endothelial cell proliferation.

[0072] Example 2:

[0073] A method for preparing a magnesium alloy vascular stent material with a n-dodecyl mercaptan nano-water-repellent layer and a thioctic acid-Fe(II) coating (bioactive coating), comprising the following steps:

[0074] The material of magnesium alloy vascular stent is ZE21B magnesium alloy.

[0075] Step 1: Pretreatment of magnesium alloy

[0076] The magnesium alloy was cut into cylinders with a diameter of 10 mm and a thickness of 3 mm. The surfaces were polished with 100-mesh, 400-mesh, 800-mesh, and 1000-mesh sandpapers in sequence until the surfaces were smooth and flat. The surfaces were then rinsed with deionized water and anhydrous ethanol in sequence, dried at 50°C for 10 min, and set aside.

[0077] Step 2: Surface fluorination treatment of magnesium alloy

[0078] The polished ZE21B magnesium alloy sheet was placed in a 24-well plate (about 1.5 cm in diameter, about 2 cm in depth, and capable of holding about 3.3 mL of solution).

[0079] Add 2 mL of 40 wt% hydrofluoric acid solution to the wells containing the magnesium alloy sheets, and place the 24-well plate in a fume hood at room temperature for 24 h;

[0080] The fluorinated ZE21B magnesium alloy sheet was taken out, rinsed with deionized water and anhydrous ethanol in sequence to remove residual hydrofluoric acid, dried at 50°C for 10 min, and set aside.

[0081] Step 3: Polydopamine deposition treatment

[0082] Prepare a 20 mM tris(hydroxymethyl)aminomethane aqueous solution and add 0.5 mol / L dilute hydrochloric acid solution dropwise to adjust the pH to 8.5;

[0083] Dissolve dopamine hydrochloride in the above-mentioned tris(hydroxymethylaminomethane)-hydrochloric acid solution to a concentration of 3.0 mg / mL, seal and stir for 30 minutes to obtain a dopamine solution;

[0084] The fluorinated ZE21B magnesium alloy sample was placed in a 24-well plate, 1.5 mL of the above-mentioned dopamine solution was added to each well, and the plate was fixed on a constant temperature shaker at 80 rpm and deposited at 30°C for 24 h.

[0085] The polydopamine-treated sample was taken out, rinsed with deionized water and anhydrous ethanol in sequence, dried at 50°C for 10 min, and set aside.

[0086] Step 4: Preparation of n-dodecylmercaptan nano-water-repellent layer

[0087] Prepare a 5.0‰ (V / V) n-dodecyl mercaptan ethanol solution, place the polydopamine sample in a 50 mL beaker, add 30 mL of n-dodecyl mercaptan solution, react at 40°C for 18 h, wash with ethanol three times, and dry at 50°C for 10 min to obtain the product.

[0088] Step 5: Preparation of lipoic acid-Fe(III) coating

[0089] A 0.3 g / mL lipoic acid solution was prepared using anhydrous ethanol as the solvent, followed by the addition of ferric chloride with a molar ratio of ferric chloride to lipoic acid of 1:500.

[0090] The magnesium alloy material containing the perfluorodecyl mercaptan nano-water-repellent layer was immersed in the above solution for 5 seconds, taken out, and then placed in an oven and dried at 50°C for 30 minutes to obtain the product.

[0091] The prepared magnesium alloy vascular stent material modified with magnesium fluoride / polydopamine / n-dodecylmercaptan water-repellent layer / lipoic acid-Fe(III) coating is placed in a sample bag and sealed for later use.

[0092] The water contact angle test was conducted on the ZE21B magnesium alloy sample with n-dodecyl mercaptan water repellent layer on the surface prepared in Example 2. The experimental results are as follows: Figure 9shown.

[0093] Figure 9 Water contact angle test of the magnesium fluoride / polydopamine / n-dodecylmercaptan water-repellent layer / lipoic acid-Fe(III) coating prepared in Example 2. After immobilizing n-dodecylmercaptan on the surface, the nano-water-repellent layer exhibited a water contact angle of 91.6°, demonstrating excellent water repellency. After modification with the lipoic acid-Fe(III) coating, the contact angle dropped to 89.8°.

[0094] The above description is only part of the embodiments of the present invention. For ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the principles of the present invention. These improvements and substitutions should also be considered as the scope of protection of the present invention.

Claims

1. A method for preparing a magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating, characterized in that: The following steps are involved: (1) Take the magnesium alloy vascular stent material, use sandpaper to polish it until the surface is flat and smooth, and then clean it, dry it, and set aside; (2) fluoriding the magnesium alloy vascular stent material of step (1) to obtain a sample having a magnesium fluoride layer on the surface; (3) depositing polydopamine on the surface of the sample in step (2); (4) dissolving a thiol-containing hydrophobic molecule in anhydrous ethanol at a concentration of 1.0-5.0‰ V / V to obtain a hydrophobic molecule solution, placing the magnesium alloy vascular stent material obtained in step (3) in the hydrophobic molecule solution, reacting for 6-24 hours at a temperature of 40°C-60°C, then rinsing with anhydrous ethanol and drying to obtain a magnesium alloy vascular stent material containing a nano-water-repellent layer; the thiol-containing hydrophobic molecule is perfluorodecyl mercaptan, perfluorooctyl mercaptan or perfluorohexyl mercaptan; (5) Dissolve lipoic acid in an organic solvent at a concentration of 0.1 g / mL to 0.5 g / mL, add an inorganic salt, and stir until completely dissolved to obtain a lipoic acid-based precursor solution, which is then prepared on the surface of a vascular stent material containing a nano-water-repellent layer and dried to obtain a bioactive coating on the surface of the nano-water-repellent layer.

2. The preparation method according to claim 1, wherein The magnesium alloy vascular stent material described in step (1) is ZE21B, WE43, AZ31 or AZ91.

3. The preparation method according to claim 1, wherein The inorganic salt described in step (5) is zinc chloride, ferric chloride, ferric sulfate, copper chloride or copper sulfate.

4. The preparation method according to claim 1, wherein The organic solvent described in step (5) is N,N-dimethylformamide, dichloromethane, isopropanol, anhydrous methanol or anhydrous ethanol.

5. The preparation method according to claim 1, wherein The bioactive coating described in step (5) is prepared by dip coating, spin coating or spray coating.

6. A magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating, prepared by the preparation method according to any one of claims 1 to 5.

7. The magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating according to claim 6, characterized in that: The thickness of the magnesium fluoride layer is 0.8 μm~3.0 μm, the thickness of the polydopamine layer is 0.5 μm~2.0 μm, the thickness of the nano-water-repellent layer is 100 nm~150 nm, and the thickness of the bioactive coating is 1.0 μm~6.0 μm.

8. Use of the magnesium alloy vascular stent material with a nano water-repellent layer and a bioactive coating according to claim 6 or 7 in the preparation of an in vivo implant.

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