Titanium alloy implant surface bionic coating and preparation method thereof

Abstract

The invention belongs to the technical field of biomimetic materials, and discloses a titanium alloy implant surface biomimetic coating and a preparation method thereof.The biomimetic coating comprises a porous titanium support layer, a micron-sized porous titanium layer is prepared through plasma spraying, and then nano-hydroxyapatite is doped to improve osteoinductivity; the graphene enhancement layer is modified, a graphene oxide film is electrochemically deposited, the graphene oxide film and the titanium substrate are covalently bonded through a silane coupling agent, and strontium ions are loaded to promote osteogenic differentiation; an antibacterial active layer and in-situ reduced graphene oxide form a three-dimensional network conductive structure, tantalum-doped carbon nitride quantum dots are loaded through ultrasonic dispersion and embedded between graphene layers to form an antibacterial phase, and then magnesium silicate nanowires are subjected to hydrothermal growth to form a bioactive phase. Through triple bionic design of porous titanium, ion release / photo-thermal response and PDA adhesion, the bone bonding strength, antibacterial property, wear resistance and corrosion resistance of a coating interface are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bionic materials, and particularly relates to a bionic coating on the surface of a titanium alloy implant and a preparation method thereof. Background Art

[0002] Natural bone tissue has a micro / nano multi-level composite structural feature, and a large number of studies also show that artificial bionic micro / nano composite structures can better promote bone integration compared with single structures. In addition, considering the complexity of the process of the implant acting, it is particularly important to make it have functions such as antibacterial, promoting angiogenesis, osteogenesis, and immunomodulation through appropriate surface modification treatment. Therefore, developing an implant with a micro-nano bionic multi-functional composite coating is considered to be one of the potential ways to improve the success rate of implants.

[0003] Titanium and its alloys (such as Ti-6Al-4V) have become the preferred materials for implants due to their unique biocompatibility. And hydroxyapatite (HA) coating, as a bioactive ceramic coating, after the implant is implanted into the human body, the HA coating will interact with human bone tissue to form osseointegration. Because the composition of the HA coating is similar to that of human bone, and it has excellent bioactivity and the advantages of being non-toxic, harmless, and non-carcinogenic, and at the same time has a good inductive growth effect on bone tissue, it has become the main material for orthopedic implants.

[0004] Currently, hydroxyapatite (HA) coating is mainly prepared directly on medical nickel-titanium alloy by micro-arc oxidation and hydrothermal treatment. Since all the calcium and phosphorus for synthesizing hydroxyapatite in the hydrothermal treatment come from the micro-arc oxidation film layer, the source of calcium and phosphorus is very limited, and the thickness of the formed hydroxyapatite layer is very limited. Secondly, the growth efficiency of hydroxyapatite under hydrothermal treatment is low, and the overall bonding strength of the coating is not high. Therefore, there is an urgent need for an excellent bionic coating to improve the comprehensive performance of implants. Summary of the Invention

[0005] To solve the deficiencies mentioned in the above background art, the purpose of the present invention is to provide a bionic coating on the surface of a titanium alloy implant and a preparation method thereof. The bionic coating includes an interface strengthening layer, a porous titanium scaffold layer, a modified graphene reinforcement layer, and an antibacterial active layer. Through the triple bionic design of porous titanium, ion release / photothermal response, and PDA adhesion, the bone-bonding strength, antibacterial property, wear resistance, and corrosion resistance of the coating interface are improved, and the comprehensive performance exceeds that of the existing HA coating.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A bionic coating on the surface of a titanium alloy implant, comprising: A porous titanium scaffold layer, which prepares a micron-level porous titanium layer by plasma spraying and then dopes nano-hydroxyapatite to enhance osteogenic induction; A modified graphene enhanced layer, an electrochemically deposited graphene oxide film, is covalently bonded to a titanium substrate through a silane coupling agent and loaded with strontium ions to promote osteogenic differentiation; An antibacterial active layer, in-situ reduction of graphene oxide to form a three-dimensional network conductive structure, loading tantalum-doped carbon nitride quantum dots into the graphene layers by ultrasonic dispersion to form an antibacterial phase, and then hydrothermally growing magnesium silicate nanowires to form a bioactive phase; The porous titanium scaffold layer, the modified graphene enhanced layer, and the antibacterial active layer are sequentially arranged on the surface of the titanium alloy implant.

[0007] Preferably, it further includes an interface strengthening layer, which is arranged between the titanium alloy implant and the porous titanium scaffold layer. The interface bonding force is enhanced by pre-depositing a 450-550 nm polydopamine film on the surface of the titanium alloy implant, and at the same time, active sites are provided to anchor graphene.

[0008] Preferably, the porosity of the porous titanium layer is 40-50%, the pore diameter is 100-300 μm, and the doping rate of nano-hydroxyapatite is 8-10 wt%.

[0009] Preferably, the thickness of the graphene oxide film in the modified graphene enhanced layer is 2-3 μm, and the loading rate of strontium ions is 8.5-8.8 wt%.

[0010] Preferably, the particle size of the tantalum-doped carbon nitride quantum dots in the antibacterial active layer is less than 10 nm, the diameter of the magnesium silicate nanowires is 45-55 nm, and the length is 1-2 μm.

[0011] A preparation method of a biomimetic coating on the surface of a titanium alloy implant, comprising the following steps: S1. First, pretreat the titanium alloy implant, then dissolve hydrochloric acid dopamine in a Tris buffer solution, and finally immerse the pretreated titanium alloy implant in the hydrochloric acid dopamine solution, shake it at a constant temperature of 50 °C for 3-5 h, blow it with nitrogen and then dry it in vacuum to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1 and ball mill for 2-4 h. Using argon and hydrogen as carrier gases, feed the powder at a rate of 25 g / min, and perform plasma spraying on the titanium alloy implant obtained in step S1, with a spray coating thickness of 140-160 μm, to form a porous titanium scaffold layer; S3. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat for 3-5 h to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S2 in the dispersion, and deposit a graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S4. Immerse the titanium alloy implant obtained in step S3 into a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 4 - 6 h, take it out and dry it under vacuum to form a modified graphene enhanced layer; S5. Disperse tantalum-doped carbon nitride quantum dots with deionized water, and then evenly drop the dispersion on the surface of the titanium alloy implant obtained in step S4, and perform vacuum-assisted infiltration at -0.08 MPa for 20 - 40 min; S6. Dissolve magnesium nitrate, sodium silicate and urea with deionized water to prepare a precursor solution, and then immerse the titanium alloy implant obtained in step S5 into the precursor solution, react at 180 °C for 8 - 12 h, and apply a 10 mT static magnetic field at the same time to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the bionic coating on the surface of the titanium alloy implant.

[0012] Preferably, the pretreatment in step S1 includes sandblasting, acid etching activation and anodic oxidation treatment, which specifically includes the following steps: A. Sandblasting: Use Al2O3 particles with a particle size of 150 - 200 μm to spray the surface of the titanium alloy implant at a pressure of 0.5 MPa for 20 - 40 s, and the surface roughness Sa of the titanium alloy implant reaches 3.1 - 3.3 μm; B. Acid etching activation: Immerse the sandblasted titanium alloy implant into the mixed acid solution, soak it at 60 °C for 8 - 10 min to obtain a pit structure with a depth of 5 - 8 μm and increase the specific surface area; C. Anodic oxidation: Immerse the acid-etched and activated titanium alloy implant into the electrolyte, perform anodic oxidation at 25 °C and a DC voltage of 20 V for 20 - 40 min to form a regular titanium dioxide nanotube array on the surface of the titanium alloy implant.

[0013] Preferably, the mixed acid solution is an aqueous solution of sulfuric acid and hydrogen peroxide, the mass concentration of sulfuric acid is 18 wt%, and the mass concentration of hydrogen peroxide is 5 wt%; the electrolyte is an ethylene glycol solution of ammonium fluoride and water, the mass concentration of ammonium fluoride is 0.5 wt%, and the mass concentration of water is 3 wt%.

[0014] Preferably, the preparation method of tantalum-doped carbon nitride quantum dots includes the following steps: (1) Mix melamine, tantalum pentachloride and sodium citrate, ball mill for 1 - 3 h, and add it to ethanol for ultrasonic dispersion to form a uniform slurry; (2) Place the slurry in a muffle furnace, heat it to 350 °C at a rate of 5 °C / min and keep it for 1 - 3 h to generate a light yellow intermediate, and then place it in a nitrogen atmosphere, heat it to 550 °C at a rate of 2 °C / min and calcine for 3 - 5 h to obtain a dark yellow tantalum-doped carbon nitride block; (3) Place the tantalum-doped carbon nitride bulk material in concentrated sulfuric acid, stir at 80 °C for 8 - 12 h, centrifuge to remove undissociated large particles, filter the supernatant through a nylon membrane, dialyze to remove free Ta ions, pre-freeze at -80 °C, and then vacuum freeze-dry to obtain pale green tantalum-doped carbon nitride quantum dot powder.

[0015] Preferably, melamine, tantalum pentachloride, and sodium citrate are mixed in a mass ratio of 20:3:1.

[0016] Advantages of the present invention: The biomimetic coating on the surface of the titanium alloy implant of the present invention includes an interface strengthening layer, a porous titanium scaffold layer, a modified graphene reinforcement layer, and an antibacterial active layer. A multi-level biomimetic structure is formed through micron pores (osseointegration) + nanotubes / nanowires (cell adhesion) + graphene network (mechanical conduction). Osteogenesis is regulated by the gradient release of Sr 2+ / Mg 2+ ions, and on-demand antibacterial is achieved by photothermal triggering of Ta-g-C3N4 QDs. Interface durability is ensured through PDA chemical adhesion + graphene mechanical interlocking. Through triple designs of structural bionics (porous titanium), functional bionics (ion release / photothermal response), and interface bionics (PDA adhesion), the comprehensive performance exceeds that of the existing HA coating. Specific embodiments

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0018] A biomimetic coating on the surface of a titanium alloy implant, comprising: A porous titanium scaffold layer, prepared by plasma spraying a micron-scale porous titanium layer, and then doping with nano-hydroxyapatite to enhance osteogenicity. The porosity of the porous titanium layer is 40 - 50%, the pore diameter is 100 - 300 μm, and the doping rate of nano-hydroxyapatite is 8 - 10 wt%. A modified graphene reinforcement layer, electrochemically depositing a graphene oxide film, covalently bonding with the titanium substrate through a silane coupling agent, and loading strontium ions to promote osteogenic differentiation. The thickness of the graphene oxide film in the modified graphene reinforcement layer is 2 - 5 nm, and the loading rate of strontium ions is 8.5 - 8.8 wt%. An antibacterial active layer, in-situ reducing graphene oxide to form a three-dimensional network conductive structure, loading tantalum-doped carbon nitride quantum dots through ultrasonic dispersion and embedding them between graphene layers to form an antibacterial phase, and then hydrothermally growing magnesium silicate nanowires to form a bioactive phase. The particle size of the tantalum-doped carbon nitride quantum dots in the antibacterial active layer is less than 10 nm, and the diameter of the magnesium silicate nanowires is 45 - 55 nm, with a length of 1 - 2 μm; The porous titanium scaffold layer, the modified graphene reinforcement layer, and the antibacterial active layer are sequentially arranged on the surface of the titanium alloy implant.

[0019] In some embodiments, it further includes an interface strengthening layer. The interface strengthening layer is arranged between the titanium alloy implant and the porous titanium scaffold layer, enhancing the interface bonding force by pre-depositing a 450 - 550 nm polydopamine film on the surface of the titanium alloy implant, and simultaneously providing active sites to anchor graphene.

[0020] Example 1: A method for surface pretreatment of a titanium alloy implant, including sandblasting, acid etching activation, and anodic oxidation treatment, specifically including the following steps: A. Sandblasting treatment: Using Al2O3 particles with a particle size of 150 - 200 μm to spray the surface of the titanium alloy implant at a pressure of 0.5 MPa for 30 s, and the surface roughness Sa of the titanium alloy implant reaches 3.2 μm; B. Acid etching activation: Immersing the sandblasted titanium alloy implant in a mixed acid solution, where the mixed acid solution includes sulfuric acid with a mass concentration of 18 wt% and hydrogen peroxide with a mass concentration of 5 wt%, soaking at 60 °C for 10 min to obtain a pit structure with a depth of 5 - 8 μm and increase the specific surface area; C. Anodic oxidation: Immersing the acid-etched and activated titanium alloy implant in an electrolyte solution, where the electrolyte is an ethylene glycol solution of ammonium fluoride and water, the mass concentration of ammonium fluoride is 0.5 wt%, and the mass concentration of water is 3 wt%. Anodize at 25 °C and a DC voltage of 20 V for 30 min to form a regular titanium dioxide nanotube array on the surface of the titanium alloy implant.

[0021] Example 2: A method for preparing tantalum-doped carbon nitride quantum dots includes the following steps: (1) Mix melamine, tantalum pentachloride, and sodium citrate in a mass ratio of 20:3:1, then ball mill for 2 h, and add to ethanol for ultrasonic dispersion to form a uniform slurry; (2) Place the slurry in a muffle furnace, heat it to 350 °C at a rate of 5 °C / min and hold for 2 h to generate a pale yellow intermediate, then place it in a nitrogen atmosphere and heat it to 550 °C at a rate of 2 °C / min for calcination for 4 h to obtain a dark yellow tantalum-doped carbon nitride bulk; (3) Place the tantalum-doped carbon nitride bulk material in concentrated sulfuric acid, stir at 80 °C for 10 h, centrifuge to remove undissociated large particles, filter the supernatant through a nylon membrane, dialyze to remove free tantalum ions, pre-freeze at -80 °C, and then vacuum freeze-dry to obtain light green tantalum-doped carbon nitride quantum dot powder.

[0022] Example 3: A biomimetic coating on the surface of a titanium alloy implant, comprising a porous titanium scaffold layer, a modified graphene reinforcement layer, and an antibacterial active layer sequentially arranged on the surface of the implant titanium alloy. The preparation method includes the following steps: S1. First, perform the pretreatment on the titanium alloy implant as described in Example 1. Then, mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1 and ball mill for 3 h. Using argon and hydrogen as carrier gases, feed the powder at a rate of 25 g / min, and perform plasma spraying on the titanium alloy implant obtained in step S1. The sprayed coating thickness is 150 μm to form a porous titanium scaffold layer; S2. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat for 4 h to obtain a stable dispersion liquid. Then, immerse the titanium alloy implant obtained in step S1 in the dispersion liquid, and deposit a 2.5-μm graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S3. Immerse the titanium alloy implant obtained in step S2 in a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 5 h, take it out and vacuum dry to form a modified graphene reinforcement layer; S4. Disperse the tantalum-doped carbon nitride quantum dots with deionized water, and then evenly drop the dispersion liquid on the surface of the titanium alloy implant obtained in step S3, and perform vacuum-assisted infiltration at -0.08 MPa for 30 min; S5. Dissolve magnesium nitrate, sodium silicate, and urea in deionized water to prepare a precursor solution. Then, immerse the titanium alloy implant obtained in step S4 in the precursor solution, react at 180 °C for 10 h, and simultaneously apply a 10 mT static magnetic field to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the biomimetic coating on the surface of the titanium alloy implant.

[0023] Example 4: A biomimetic coating on the surface of a titanium alloy implant, comprising an interface strengthening layer, a porous titanium scaffold layer, a modified graphene reinforcement layer, and an antibacterial active layer sequentially arranged on the surface of the implant titanium alloy. The preparation method includes the following steps: S1. First, perform pretreatment on the titanium alloy implant, then dissolve dopamine hydrochloride in a Tris buffer solution, and finally immerse the pretreated titanium alloy implant in the dopamine hydrochloride solution, keep it at a constant temperature of 50 °C and shake for 3 h, purge with nitrogen and then vacuum dry to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1, then ball mill for 4 h. Using argon and hydrogen as carrier gases, feed the powder at a rate of 25 g / min, and perform plasma spraying on the titanium alloy implant obtained in step S1. The sprayed coating thickness is 140 μm to form a porous titanium scaffold layer; S3. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat for 5 h to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S2 into the dispersion, and deposit a 2.2-μm graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S4. Immerse the titanium alloy implant obtained in step S3 into a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 6 h, take it out and dry it in vacuum to form a modified graphene reinforcement layer; S5. Disperse tantalum-doped carbon nitride quantum dots with deionized water, and then evenly drop the dispersion on the surface of the titanium alloy implant obtained in step S4, and perform vacuum-assisted infiltration at -0.08 MPa for 20 min; S6. Dissolve magnesium nitrate, sodium silicate and urea with deionized water to prepare a precursor solution, and then immerse the titanium alloy implant obtained in step S5 into the precursor solution, react at 180 °C for 12 h, and apply a 10 mT static magnetic field at the same time to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the biomimetic coating on the surface of the titanium alloy implant.

[0024] Example 5: A biomimetic coating on the surface of a titanium alloy implant, including an interface strengthening layer, a porous titanium scaffold layer, a modified graphene reinforcement layer and an antibacterial active layer sequentially arranged on the surface of the titanium alloy of the implant. Its preparation method includes the following steps: S1. First, pre-treat the titanium alloy implant, then dissolve dopamine hydrochloride in a Tris buffer solution, and finally immerse the pre-treated titanium alloy implant into the dopamine hydrochloride solution, oscillate at a constant temperature of 50 °C for 5 h, purge with nitrogen and then dry it in vacuum to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1, then ball mill for 2 h. Using argon and hydrogen as carrier gases, feed the powder at a rate of 25 g / min, and perform plasma spraying on the titanium alloy implant obtained in step S1. The sprayed coating thickness is 160 μm to form a porous titanium scaffold layer; S3. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat for 3 h to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S2 into the dispersion, and deposit a 2.8-μm graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S4. Immerse the titanium alloy implant obtained in step S3 into a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 4 h, take it out and dry it in vacuum to form a modified graphene reinforcement layer; S5. Disperse the tantalum-doped carbon nitride quantum dots in deionized water, and then evenly drop and coat the dispersion on the surface of the titanium alloy implant obtained in step S4, and perform vacuum-assisted infiltration at -0.08 MPa for 40 min; S6. Dissolve magnesium nitrate, sodium silicate and urea in deionized water to prepare a precursor solution, and then immerse the titanium alloy implant obtained in step S5 into the precursor solution, react at 180 °C for 8 h, and apply a 10 mT static magnetic field at the same time to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the bionic coating on the surface of the titanium alloy implant.

[0025] Example 6: A bionic coating on the surface of a titanium alloy implant, comprising an interface strengthening layer, a porous titanium scaffold layer, a modified graphene reinforcement layer and an antibacterial active layer sequentially arranged on the surface of the titanium alloy implant. The preparation method comprises the following steps: S1. First pre-treat the titanium alloy implant, then dissolve dopamine hydrochloride in a Tris buffer solution, and finally immerse the pre-treated titanium alloy implant into the dopamine hydrochloride solution, oscillate at a constant temperature of 50 °C for 4 h, perform nitrogen purging and then vacuum drying to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1 and ball mill for 3 h. Use argon and hydrogen as carrier gases and feed powder at a rate of 25 g / min to perform plasma spraying on the titanium alloy implant obtained in step S1, with a spray coating thickness of 150 μm to form a porous titanium scaffold layer; S3. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, perform ultrasonic treatment for 4 h to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S2 into the dispersion, and deposit a 2.5 μm graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S4. Immerse the titanium alloy implant obtained in step S3 into a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 5 h, take it out and perform vacuum drying to form a modified graphene reinforcement layer; S5. Disperse the tantalum-doped carbon nitride quantum dots in deionized water, and then evenly drop and coat the dispersion on the surface of the titanium alloy implant obtained in step S4, and perform vacuum-assisted infiltration at -0.08 MPa for 30 min; S6. Dissolve magnesium nitrate, sodium silicate and urea in deionized water to prepare a precursor solution, and then immerse the titanium alloy implant obtained in step S5 into the precursor solution, react at 180 °C for 10 h, and apply a 10 mT static magnetic field at the same time to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the bionic coating on the surface of the titanium alloy implant.

[0026] Comparative Example 1: A biomimetic coating on the surface of a titanium alloy implant, including an interface strengthening layer, a modified graphene reinforcement layer, and an antibacterial active layer sequentially arranged on the surface of the implant titanium alloy. The preparation method includes the following steps: S1. First, pre-treat the titanium alloy implant, then dissolve dopamine hydrochloride in Tris buffer solution, and finally immerse the pre-treated titanium alloy implant in the dopamine hydrochloride solution, shake it at a constant temperature of 50°C for 4 hours, purge it with nitrogen, and then dry it in vacuum to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat it for 4 hours to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S1 in the dispersion, and deposit a 2.5-μm graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S3. Immerse the titanium alloy implant obtained in step S2 in a mixed solution of strontium chloride and ascorbic acid, react at 60°C for 5 hours, take it out and dry it in vacuum to form a modified graphene reinforcement layer; S4. Disperse tantalum-doped carbon nitride quantum dots with deionized water, and then evenly drip the dispersion on the surface of the titanium alloy implant obtained in step S3, and perform vacuum-assisted penetration at -0.08 MPa for 30 minutes; S5. Dissolve magnesium nitrate, sodium silicate, and urea in deionized water to prepare a precursor solution, and then immerse the titanium alloy implant obtained in step S4 in the precursor solution, react at 180°C for 10 hours, and simultaneously apply a 10-mT static magnetic field to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the biomimetic coating on the surface of the titanium alloy implant.

[0027] Comparative Example 2: A biomimetic coating on the surface of a titanium alloy implant, including an interface strengthening layer, a porous titanium scaffold layer, and an antibacterial active layer sequentially arranged on the surface of the implant titanium alloy. The preparation method includes the following steps: S1. First, pre-treat the titanium alloy implant, then dissolve dopamine hydrochloride in Tris buffer solution, and finally immerse the pre-treated titanium alloy implant in the dopamine hydrochloride solution, shake it at a constant temperature of 50°C for 4 hours, purge it with nitrogen, and then dry it in vacuum to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1, ball-mill them for 3 hours, use argon and hydrogen as carrier gases, and feed the powder at a rate of 25 g / min to perform plasma spraying on the titanium alloy implant obtained in step S1, with a spray coating thickness of 150 μm to form a porous titanium scaffold layer; S3. Disperse tantalum-doped carbon nitride quantum dots with deionized water, and then evenly drip the dispersion on the surface of the titanium alloy implant obtained in step S2, and perform vacuum-assisted penetration at -0.08 MPa for 30 minutes; S4. Dissolve magnesium nitrate, sodium silicate and urea in deionized water to prepare a precursor solution. Then immerse the titanium alloy implant obtained in step S3 into the precursor solution, react at 180 °C for 10 h, and apply a 10 mT static magnetic field simultaneously to induce the vertical growth of nanowires to form an antibacterial active layer, thus completing the preparation of the bionic coating on the surface of the titanium alloy implant.

[0028] Comparative Example 3: A bionic coating on the surface of a titanium alloy implant, including an interface strengthening layer, a porous titanium scaffold layer and a modified graphene reinforcement layer sequentially arranged on the surface of the implant titanium alloy. Its preparation method includes the following steps: S1. First, pre-treat the titanium alloy implant, then dissolve dopamine hydrochloride in Tris buffer solution, and finally immerse the pre-treated titanium alloy implant into the dopamine hydrochloride solution, oscillate at a constant temperature of 50 °C for 4 h, blow with nitrogen and then dry in vacuum to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1 and ball mill for 3 h. Use argon and hydrogen as carrier gases and feed powder at a rate of 25 g / min to perform plasma spraying on the titanium alloy implant obtained in step S1, with a spray coating thickness of 150 μm to form a porous titanium scaffold layer; S3. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat for 4 h to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S2 into the dispersion, and deposit a 2.5 μm graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S4. Immerse the titanium alloy implant obtained in step S3 into a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 5 h, take it out and dry in vacuum to form a modified graphene reinforcement layer, thus completing the preparation of the bionic coating on the surface of the titanium alloy implant.

[0029] Performance detection 1. Bone-bonding strength detection Make the titanium alloy implant material into a cylinder with a size of diameter 4 mm * length 10 mm, and then prepare a bionic coating on the surface of the titanium alloy implant material according to the methods in Example 3, 6 and Comparative Examples 1-3. Then implant it into the femoral condyle of New Zealand white rabbits (drill a hole with a diameter of 4.2 mm). Take samples 8 weeks after the operation. Keep the bone-implant interface moist with physiological saline, and perform bone-bonding strength testing according to the method in ISO-13779-2 standard. Use a universal material testing machine for testing, with a loading rate of 1 mm / min, and record the maximum shear force F max , repeat 3 - 5 times, calculate the bone-bonding strength, and the calculation formula is C = F max / π*d*h, where C is the bone-bonding strength (MPa), d is the diameter (mm), and h is the implant length (mm). The obtained data is shown in Table 1 below.

[0030] Table 1 Test Results of Osteointegration Strength of Titanium Alloy Implants

[0031] It can be seen from the data in Table 1 that the absence of the porous titanium scaffold layer in Comparative Example 1 has the greatest impact on the osteointegration strength of the titanium alloy implant material. In the present invention, the porous titanium scaffold layer is prepared by plasma spraying to form a micron-level porous titanium layer, imitating the trabecular bone structure, promoting the migration of osteoblasts and vascularization, and doping with nano-hydroxyapatite to enhance osteogenic induction, which can effectively improve the osteointegration strength of the titanium alloy implant.

[0032] 2. Antibacterial Rate Test The titanium alloy implant material was made into a square piece of 10mm * 10mm * 1mm, and then a biomimetic coating was prepared on the surface of the titanium alloy implant material according to the methods in Examples 3, 6 and Comparative Examples 1-3. Then, a bacterial suspension of 10 5 CFU / mL Staphylococcus aureus (ATCC 6538) was inoculated on the surface of the sample coating. One group was irradiated with 808nm NIR (near-infrared light) at a intensity of 1W / cm 2 for 10 min, and the other group was not irradiated with NIR (near-infrared light). Then, a polyethylene film was covered and cultured at 37 °C for 24 h. After rinsing with PBS, the bacterial suspension was collected by ultrasonic oscillation (40 kHz, 5 min). The number of surviving bacteria was measured by the plate dilution coating method, and the colony numbers before and after treatment were compared. The antibacterial rate was calculated by repeating 3-5 times, and the data are shown in Table 2 below.

[0033] Table 2 Test Results of Antibacterial Properties of Biomimetic Coatings on the Surface of Titanium Alloy Implants

[0034] It can be seen from the data in Table 2 that in Comparative Example 3, the antibacterial activity layer is missing, and the antibacterial property of the coating decreases significantly. In the present invention, the antibacterial activity layer, the near-infrared responsive photothermal effect of Ta-QDs triggers instantaneous sterilization, and Mg2SiO4 nanowires continuously release Mg 2+ which can up-regulate the gene expression of a series of osteogenic-related cytokines, such as CCL5, IL-1ra, IL-8, TGF-β1, BMP2, VEGFA and IL-10. In addition, in Comparative Example 2, the antibacterial property of the coating decreased slightly because the broadband light absorption of rGO in the modified graphene enhancement layer enhanced the photothermal conversion efficiency of Ta-QDs, which can improve its antibacterial effect.

[0035] 3. Abrasion Resistance Test The titanium alloy implant material was made into a circular sheet with a diameter of 10 mm and a thickness of 3 mm. Then, according to the methods in Examples 3 and 6 and Comparative Examples 1 to 3, a biomimetic coating was prepared on the surface of the titanium alloy implant material. The wear resistance test of the coating was carried out according to the ASTM F1978-18 standard. The counterbody was an Al2O3 ball with a diameter of 6 mm, lubricated with SBF (simulated body fluid) at 25°C, with a load of 5 N and a rotation speed of 60 rpm. The total number of cycles was 1 million times. The wear scar volume was measured by a white light interferometer, and the friction coefficient was recorded. The data obtained are shown in Table 3 below. The formula of SBF (simulated body fluid) is: 8.035 g / L of NaCl, 0.355 g / L of NaHCO3, 0.225 g / L of KCl, 0.292 g / L of CaCl2·2H2O, 0.311 g / L of MgCl2·6H2O, and the balance is deionized water.

[0036] Table 3 Wear resistance test results of the biomimetic coating on the surface of the titanium alloy implant

[0037] It can be seen from the data in Table 3 that the missing porous titanium scaffold layer in Comparative Example 1 and the missing interface strengthening layer in Example 3 significantly affect the wear resistance. Among them, the porous structure of the porous titanium scaffold layer absorbs frictional energy through plastic deformation, reducing coating spalling. The catechol groups of PDA in the interface strengthening layer form chelation bonds with the titanium substrate and anchor graphene through π-π stacking, thereby improving the bonding strength of the coating.

[0038] 4. Corrosion resistance test The titanium alloy implant material was made into a cylinder with a diameter of 10 mm and a length of 15 mm. Then, according to the methods in Examples 3 and 6 and Comparative Examples 1 to 3, a biomimetic coating was prepared on the surface of the titanium alloy implant material. After ultrasonic cleaning with ethanol / acetone and drying with nitrogen, it was used as the working electrode. A saturated calomel electrode (SCE) was used as the reference electrode, and SBF (simulated body fluid) was used as the electrolyte. Maintaining at 37°C, the stable potential when the electrolyte reached dynamic equilibrium was measured, that is, the self-corrosion potential E corr , of the material. A polarization curve scan was carried out using an electrochemical workstation Gamry Reference 3000. The scan range was: -0.5 V ~ +1.5 V (vs OCP), the scan rate was: 1 mV / s, and the current value was recorded every 0.1 mV. The data was processed using Gamry Echem Analyst software. The ±250 mV linear region was selected, and the cathode slope ( β a ) / anode slope ( β c ) was fitted to calculate the corrosion current density i corr = β a β c / 2.303( β a + β c )·( di / dE ) E＝Ecorr , the data obtained is shown in Table 4 below.

[0039] Table 4 Corrosion Resistance Test Results of the Biomimetic Coating on the Surface of Titanium Alloy Implants

[0040] It can be seen from the data in Table 4 that the modified graphene reinforcement layer and the interface strengthening layer contribute significantly to corrosion prevention. Among them, the dense lamellar structure of rGO in the modified graphene reinforcement layer blocks the penetration path of Cl⁻, and the high electron mobility of graphene promotes the repair of the passive film. While the interface strengthening layer PDA fills the microcracks in the coating, which can inhibit the penetration of the electrolyte.

[0041] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0042] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A biomimetic coating on the surface of a titanium alloy implant, characterized in that, Comprising: A porous titanium scaffold layer, where a micron-scale porous titanium layer is prepared by plasma spraying and then doped with nano-hydroxyapatite to enhance osteoinductivity; A modified graphene reinforcement layer, where a graphene oxide film is electrochemically deposited, covalently bonded to the titanium substrate through a silane coupling agent, and loaded with strontium ions to promote osteogenic differentiation; An antibacterial active layer, where graphene oxide is in-situ reduced to form a three-dimensional network conductive structure, and tantalum-doped carbon nitride quantum dots are loaded through ultrasonic dispersion and embedded between graphene layers to form an antibacterial phase, and then magnesium silicate nanowires are hydrothermally grown to form a bioactive phase; The porous titanium scaffold layer, the modified graphene reinforcement layer, and the antibacterial active layer are sequentially arranged on the surface of the titanium alloy implant.

2. The biomimetic coating on the surface of the titanium alloy implant according to claim 1, wherein, It further includes an interface strengthening layer, which is arranged between the titanium alloy implant and the porous titanium scaffold layer. The interface bonding force is enhanced by pre-depositing a 450 - 550 nm polydopamine film on the surface of the titanium alloy implant, and at the same time, active sites are provided to anchor graphene.

3. The biomimetic coating on the surface of the titanium alloy implant according to claim 1, wherein The porosity of the porous titanium layer is 40 - 50%, the pore diameter is 100 - 300 μm, and the doping rate of nano-hydroxyapatite is 8 - 10 wt%.

4. The biomimetic coating on the surface of the titanium alloy implant according to claim 1, wherein, The thickness of the graphene oxide film in the modified graphene reinforcement layer is 2 - 3 μm, and the loading rate of strontium ions is 8.5 - 8.8 wt%.

5. The biomimetic coating on the surface of the titanium alloy implant according to claim 1, characterized in that, The particle size of the tantalum-doped carbon nitride quantum dots in the antibacterial active layer is less than 10 nm, the diameter of the magnesium silicate nanowires is 45 - 55 nm, and the length is 1 - 2 μm.

6. The preparation method of the bionic coating on the surface of the titanium alloy implant according to any one of claims 1 to 5, characterized in that, Including the following steps: S1. First, pre-treat the titanium alloy implant, then dissolve dopamine hydrochloride in a Tris buffer solution, and finally immerse the pre-treated titanium alloy implant in the dopamine hydrochloride solution, shake it at a constant temperature of 50 °C for 3 - 5 h, purge it with nitrogen and then dry it in vacuum to form an interface strengthening layer on the surface of the titanium alloy implant; S2. Mix titanium powder and nano-hydroxyapatite in a mass ratio of 9:1 and then ball mill for 2 - 4 h. Using argon and hydrogen as carrier gases, feed the powder at a rate of 25 g / min, and perform plasma spraying on the titanium alloy implant obtained in step S1. The spray coating thickness is 140 - 160 μm to form a porous titanium scaffold layer; S3. Add graphene oxide and γ-aminopropyltriethoxysilane to an ethanol solution, ultrasonically treat for 3 - 5 h to obtain a stable dispersion, and then immerse the titanium alloy implant obtained in step S2 in the dispersion to deposit a graphene oxide film on the surface of the titanium alloy implant by electrophoretic deposition; S4. Immerse the titanium alloy implant obtained in step S3 in a mixed solution of strontium chloride and ascorbic acid, react at 60 °C for 4 - 6 h, take it out and dry it in vacuum to form a modified graphene reinforcement layer; S5. Disperse the tantalum-doped carbon nitride quantum dots with deionized water, and then evenly drop the dispersion on the surface of the titanium alloy implant obtained in step S4, and perform vacuum-assisted infiltration at -0.08 MPa for 20 - 40 min; S6. Dissolve magnesium nitrate, sodium silicate, and urea with deionized water to prepare a precursor solution, and then immerse the titanium alloy implant obtained in step S5 in the precursor solution, react at 180 °C for 8 - 12 h, and at the same time apply a 10 mT static magnetic field to induce the vertical growth of nanowires to form an antibacterial active layer, completing the preparation of the bionic coating on the surface of the titanium alloy implant.

7. The preparation method of the bionic coating on the surface of the titanium alloy implant according to claim 6, characterized in that, The pretreatment in step S1 includes sandblasting, acid etching activation, and anodic oxidation treatment, and specifically includes the following steps: A. Sandblasting treatment: Spraying the surface of the titanium alloy implant with Al2O3 particles with a particle size of 150 - 200 μm at a pressure of 0.5 MPa for 20 - 40 s, so that the surface roughness Sa of the titanium alloy implant reaches 3.1 - 3.3 μm; B. Acid etching activation: Immersing the sandblasted titanium alloy implant in the mixed acid solution and soaking it at 60 °C for 8 - 10 min to obtain a pit structure with a depth of 5 - 8 μm and increase the specific surface area; C. Anodic oxidation: Immersing the acid-etched and activated titanium alloy implant in the electrolyte and performing anodic oxidation at 25 °C and a DC voltage of 20 V for 20 - 40 min to form a regular titanium dioxide nanotube array on the surface of the titanium alloy implant.

8. The biomimetic coating on the surface of the titanium alloy implant according to claim 7, characterized in that, The mixed acid solution is an aqueous solution of sulfuric acid and hydrogen peroxide. The mass concentration of sulfuric acid is 18 wt%, and the mass concentration of hydrogen peroxide is 5 wt%. The electrolyte is an ethylene glycol solution of ammonium fluoride and water. The mass concentration of ammonium fluoride is 0.5 wt%, and the mass concentration of water is 3 wt%.

9. The preparation method of the bionic coating on the surface of the titanium alloy implant according to claim 6, characterized in that, The preparation method of the tantalum-doped carbon nitride quantum dots includes the following steps: (1) Mixing melamine, tantalum pentachloride, and sodium citrate and ball-milling for 1 - 3 h, then adding to ethanol and ultrasonically dispersing to form a uniform slurry; (2) Placing the slurry in a muffle furnace, heating it to 350 °C at a rate of 5 °C / min and holding for 1 - 3 h to generate a light yellow intermediate, then placing it in a nitrogen atmosphere and heating to 550 °C at a rate of 2 °C / min and calcining for 3 - 5 h to obtain a dark yellow tantalum-doped carbon nitride block; (3) Placing the tantalum-doped carbon nitride block material in concentrated sulfuric acid, stirring at 80 °C for 8 - 12 h, centrifuging to remove undissociated large particles, filtering the supernatant through a nylon membrane, dialyzing to remove free Ta ions, pre-freezing at -80 °C, and then vacuum freeze-drying to obtain a light green tantalum-doped carbon nitride quantum dot powder.

10. The preparation method of the bionic coating on the surface of the titanium alloy implant according to claim 9, characterized in that, The melamine, tantalum pentachloride, and sodium citrate are mixed in a mass ratio of 20:3:1.

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