A method for modifying the surface of a biomedical titanium alloy

Abstract

The present application relates to a kind of biological medical titanium alloy surface modification method, belong to laser application technical field.The method first utilizes femtosecond laser to process groove-micro ripple composite structure on the surface of clean polished nickel titanium alloy material;Then, rich nanometer sheet is formed on the basis of the structure by alkali heat treatment, and groove-micro ripple-nanometer sheet multistage micro-nano composite structure is obtained;Subsequently, the multistage micro-nano composite structure is placed in the alkaline Tris buffer solution containing hydrochloric acid dopamine to coat polydopamine coating;Finally, the multistage micro-nano composite structure with polydopamine coating is placed in silver nitrate solution to load silver ion, complete titanium alloy surface modification, realize the promotion of titanium alloy bioactivity, bone integration ability and anti-bacterial infection ability.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for surface modification of biomedical titanium alloy, belonging to the technical field of laser application. BACKGROUND

[0002] Titanium alloy, especially nickel-titanium alloy, has been widely used in biomedical field, especially as bone implant material, due to its good mechanical properties, corrosion resistance and biocompatibility. However, traditional titanium alloy materials still face key problems such as insufficient bioactivity, poor bone integration and easy bacterial infection in bone implant applications.

[0003] In order to solve these problems, researchers are constantly exploring new surface modification techniques to enhance the performance of titanium alloy materials. Among them, femtosecond laser processing technology shows great potential in material surface modification due to its high precision, high energy density and non-contact processing characteristics. Femtosecond laser can create complex micro-nano structures on the material surface, which can significantly increase the specific surface area of the material, promote the interaction between cells and the material surface, and thus improve the bioactivity and bone integration ability of the material. On the other hand, alkali heat treatment as another effective surface modification method is also widely studied and applied to improve the biocompatibility of titanium alloy materials. Alkali heat treatment can improve the surface chemical properties of the material by treating the material in a high-temperature alkaline environment, increase the hydrophilicity of the material, and help to further promote cell adhesion and proliferation on the material surface. In addition, alkali heat treatment can also introduce more functional groups on the material surface, providing favorable conditions for subsequent coating or loading treatment.

[0004] In existing research, for example, Liang Chunying proposed a method of combining femtosecond laser with alkali treatment to improve the bioactivity of titanium surface, but it focuses on the bone integration ability of the material and does not specifically focus on the antibacterial function of the material. Guan Yingchun et al. proposed a method for preparing an antibacterial surface on an implanted medical device, which creates a hydrophobic antibacterial adhesion surface by using ultrafast laser-induced micro-nano structures. Then, a copper or other metal nanoparticle film is deposited by plating process to prepare a bactericidal film, and finally an antibacterial surface is obtained. However, this method is not conducive to cell adhesion, and does not specifically focus on the osteogenic ability of bone implant applications and the bioactivity of the material. At present, there is still a lack of a titanium alloy surface modification method with excellent comprehensive performance, simple process and easy control. In particular, for the application of biomedical titanium alloy in bone implants, there is a need for a surface modification technology that can not only improve bioactivity and significantly improve the integration ability with bone tissue, but also effectively prevent bacterial infection.

[0005] Therefore, the application proposes a titanium alloy surface modification method combining femtosecond laser processing, alkali heat treatment, polydopamine layer coating and silver ion loading, aiming to prepare a biomedical titanium alloy material with excellent bioactivity and antibacterial ability through a multi-step synergistic treatment, so as to solve the problems of low bioactivity, poor bone integration and bacterial infection of the current titanium alloy in the application of bone implants. SUMMARY

[0006] The purpose of the application is to solve the problems of low bioactivity, poor bone integration and bacterial infection of biomedical titanium alloy in the application of bone implants, and to provide a biomedical titanium alloy surface modification method. The implementation of the method includes four core steps of femtosecond laser processing, alkali heat treatment, polydopamine layer coating and silver ion loading. The application first uses femtosecond laser to process a groove-micro-ripple composite structure on the surface of a clean and polished nickel-titanium alloy material. Then, rich nanosheets are formed on the basis of the structure through alkali heat treatment, obtaining a groove-micro-ripple-nanosheet multi-level micro-nano composite structure. Subsequently, the multi-level micro-nano composite structure is placed in an alkaline Tris buffer solution containing hydrochloric acid dopamine to coat a polydopamine coating. Finally, the multi-level micro-nano composite structure with the polydopamine coating is placed in a silver nitrate solution to load silver ions. Femtosecond laser and alkali heat treatment improve the biological inertness of titanium alloy, enhance the hydrophilicity of the material, promote the adhesion of osteoblasts on the material, and improve the integration ability of the biomedical titanium alloy material and bone tissue. The polydopamine layer coating and silver ion loading treatment improve the antibacterial infection ability of the biomedical titanium alloy material, so that it can be applied to the performance improvement of bone implants.

[0007] To achieve the above application purposes, the application provides the following technical solutions:

[0008] A biomedical titanium alloy surface modification method, comprising the following steps:

[0009] Step one: ultrasonic cleaning and drying of polished nickel-titanium alloy material.

[0010] Step two: using multiple mirrors to direct femtosecond laser to the surface of the nickel-titanium alloy material to be processed, and vertically focusing through an optical lens to the surface of the nickel-titanium alloy material.

[0011] Step three: selecting a sapphire femtosecond laser processing system, setting the parameters of femtosecond laser processing frequency, power, scanning speed and scanning interval, processing at the focal point, and then ultrasonic cleaning and drying after processing.

[0012] Step four: placing the nickel-titanium alloy sample with micro-nano surface structure prepared in step three into a high-temperature reaction kettle, adding an appropriate amount of alkali solution for alkali heat treatment, and then ultrasonic cleaning and drying after the treatment is completed.

[0013] Step five: Put the sample prepared in step four into the alkaline Tris buffer solution containing dopamine hydrochloride to form a polydopamine coating on it.

[0014] Step six: Put the sample prepared in step five into the silver nitrate solution to generate nano-silver on it.

[0015] The specific implementation steps of step three are as follows:

[0016] (1) Load the glass slide fixed with clean nickel-titanium alloy material onto the high-precision six-degree-of-freedom translation table.

[0017] (2) Select a sapphire femtosecond laser processing system, the femtosecond laser wavelength is 800nm, select a 5 times processing objective lens, set the femtosecond laser repetition frequency to 1000Hz, set the femtosecond laser processing power to 8-30mW, the scanning speed is 500-2000um / s, the scanning interval is 8-20um, and the focus is processed.

[0018] The specific implementation steps of step four are as follows:

[0019] An alkali solution with a concentration of 1-5M is configured by sodium hydroxide and deionized water, the alkali solution and the sample prepared in step three are placed in a high-pressure reaction kettle with polytetrafluoroethylene, and then the high-pressure reaction kettle is placed in a muffle furnace, the reaction temperature is set to 80°, and the reaction is carried out for 12-24h.

[0020] The specific implementation steps of step five are as follows:

[0021] An alkaline Tris buffer solution with a pH value of 8-10 is selected as the solvent, and a dopamine hydrochloride solution with a concentration of 1mg / ml-3mg / ml is configured.

[0022] The specific implementation steps of step six are as follows:

[0023] A silver nitrate solution with a concentration of 10mM-50mM is configured, the sample prepared in step five is placed in the silver nitrate solution, and the reaction is carried out for 1h-12h under light shielding conditions.

[0024] Advantages:

[0025] 1. The biological medical titanium alloy surface modification method can improve the integration ability of biological medical titanium alloy material (such as nickel-titanium alloy) and bone tissue and the antibacterial infection ability.

[0026] 2. The biological titanium alloy surface modification method of the present application can realize the machining of titanium alloy materials with different shapes and sizes by combining the ability of high-precision six-degree-of-freedom translation table to realize patterned machining.

[0027] 3. The biological titanium alloy surface modification method of the present application can prepare biological titanium alloy materials with good hydrophilicity, excellent cell compatibility in vitro, no cytotoxicity, and can promote cell adhesion and proliferation.

[0028] 4. The biological titanium alloy surface modification method of the present application can effectively inhibit the formation of biofilm by preparing a groove-micro-ridge-nanosheet multi-level micro-nano composite structure, and the prepared material surface has excellent antibacterial infection ability by combining the bactericidal ability of the nano-silver attached to the structure surface.

[0029] 5. The biological titanium alloy surface modification method of the present application can provide abundant drug loading space and has excellent drug loading capacity by preparing a groove-micro-ridge-nanosheet multi-level micro-nano composite structure with high specific surface area.

[0030] 6. The biological titanium alloy surface modification method of the present application, the groove-micro-ridge-nanosheet multi-level micro-nano composite structure biological titanium alloy material preparation method is flexible and simple, the process parameters are easy to control, and the laser technology field application is easy to realize. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the optical path diagram of the femtosecond laser machining of the present application.

[0032] Figure 2 is the SEM image of the material prepared in the embodiment of the present application. Wherein (a) is the SEM image of the nickel-titanium alloy sample after femtosecond laser machining; (b) is the SEM image of the nickel-titanium alloy sample after femtosecond laser machining and alkali heat treatment; (c) is the SEM image of the nickel-titanium alloy sample after femtosecond laser machining, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver.

[0033] Figure 3 is the contact angle test result of the embodiment of the present application. Wherein (a) is the original polished nickel-titanium alloy surface, (b) is the surface of the nickel-titanium alloy sample after femtosecond laser machining, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver.

[0034] Figure 4Figure 1 is a fluorescence microscopic image of the osteoblast (MC3T3-E1, after co-culturing for 24 hours) viability of the modified biomedical titanium alloy material prepared in an embodiment of the present application. Among them, (a) is the survival of osteoblasts on the surface of the original polished nickel-titanium alloy; (b) is the survival of osteoblasts on the surface of the nickel-titanium alloy sample after femtosecond laser processing; (c) is the survival of osteoblasts on the surface of the nickel-titanium alloy sample after femtosecond laser processing and alkali heat treatment; (d) is the survival of osteoblasts on the surface of the nickel-titanium alloy sample after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver.

[0035] Figure 5 Figure 2 is a fluorescence microscopic image of the osteoblast (MC3T3-E1, after co-culturing for 24 hours) adhesion of the modified biomedical titanium alloy material prepared in an embodiment of the present application. Among them, (a) is the adhesion of osteoblasts on the surface of the original polished nickel-titanium alloy; (b) is the adhesion of osteoblasts on the surface of the nickel-titanium alloy sample after femtosecond laser processing; (c) is the adhesion of osteoblasts on the surface of the nickel-titanium alloy sample after femtosecond laser processing and alkali heat treatment; (d) is the adhesion of osteoblasts on the surface of the nickel-titanium alloy sample after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver.

[0036] Figure 6 Figure 3 is a fluorescence microscopic image of the S. aureus colonization on the modified biomedical titanium alloy material prepared in an embodiment of the present application. (a) is the S. aureus colonization on the surface of the original polished nickel-titanium alloy; (b) is the S. aureus colonization on the surface of the nickel-titanium alloy sample after femtosecond laser processing; (c) is the S. aureus colonization on the surface of the nickel-titanium alloy sample after femtosecond laser processing and alkali heat treatment; (d) is the S. aureus colonization on the surface of the nickel-titanium alloy sample after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver.

[0037] Figure 7 Figure 4 is a fluorescence microscopic image of the E. coli colonization on the modified biomedical titanium alloy material prepared in an embodiment of the present application. Among them, (a) is the E. coli colonization on the surface of the original polished nickel-titanium alloy; (b) is the E. coli colonization on the surface of the nickel-titanium alloy sample after femtosecond laser processing; (c) is the E. coli colonization on the surface of the nickel-titanium alloy sample after femtosecond laser processing and alkali heat treatment; (d) is the E. coli colonization on the surface of the nickel-titanium alloy sample after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver.

[0038] Wherein, 1 represents femtosecond laser; 2 represents continuous attenuation piece; 3 represents first mirror; 4 represents second mirror; 5 represents light shutter; 6 represents third mirror; 7 represents focusing lens; 8 represents nickel-titanium alloy material to be processed; 9 represents six-degree-of-freedom translation stage; 10 represents dichroic mirror; 11 represents white light source; 12 represents CCD camera; 13 represents computer. DETAILED DESCRIPTION

[0039] The application will be described in detail below with reference to the drawings and examples.

[0040] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0041] Example 1

[0042] The surface modification method of the biological titanium alloy in this example comprises the following specific steps:

[0043] Step one: the polished nickel-titanium alloy sample with a surface roughness less than 5 angstroms is ultrasonically cleaned with deionized water and anhydrous ethanol solution at room temperature for 5 minutes.

[0044] Step two: the cleaned sample in step one is blown dry with an ear cleaning ball to obtain a clean nickel-titanium alloy sample.

[0045] Step three: the nickel-titanium alloy is processed by using the femtosecond laser processing system as shown in Figure 1 Wherein, 1 represents femtosecond laser; 2 represents continuous attenuation piece; 3 represents first mirror; 4 represents second mirror; 5 represents light shutter; 6 represents third mirror; 7 represents focusing lens; 8 represents nickel-titanium alloy material to be processed; 9 represents six-degree-of-freedom translation stage; 10 represents dichroic mirror; 11 represents white light source; 12 represents CCD camera; 13 represents computer. The laser generated by the femtosecond laser passes through the continuous attenuation piece, the first mirror, the second mirror, the light shutter, the third mirror and the focusing lens in sequence and is focused on the surface of the nickel-titanium alloy material to be processed. The computer controls the opening and closing of the light shutter and the movement of the six-degree-of-freedom translation stage. The white light generated by the white light source passes through the dichroic mirror, the third mirror and the focusing lens in sequence, is irradiated onto the surface of the nickel-titanium alloy material to be processed and is reflected to the CCD camera in sequence along the focusing lens, the third mirror and the dichroic mirror to generate real-time imaging of the processing area. The laser processing parameters are specifically set as follows: the wavelength of the femtosecond laser is 800 nm, the repetition frequency is 1000 Hz, the processing objective lens is selected to be 5 times, the light stop makes the diameter of the light spot before the focusing of the objective lens to be 5 mm, the laser power is 10 mW, the scanning speed is 600 μm / s, the scanning interval is 10 um, the focus is processed and the whole processing process is blown with high-pressure nitrogen to remove the chips, so as to process large-area and consistent micro-nano structures.

[0046] Step four: configure the alkali liquor with a concentration of 5M which is composed of sodium hydroxide and deionized water, put the alkali liquor and the sample prepared in step three into a high-pressure reaction kettle with a lining of polytetrafluoroethylene, tightly cover the high-pressure reaction kettle, then put the high-pressure reaction kettle into a muffle furnace, keep the reaction temperature at 80 DEG by setting the temperature rising program of the muffle furnace, and react for 24h, after the treatment, clean and dry.

[0047] Step five: select Tris buffer with a pH value of 8.5 as a solvent, configure a dopamine hydrochloride solution with a concentration of 2mg / mL, then immerse the sample prepared in step four in the dopamine hydrochloride solution and stand for 24h, after the treatment, clean and dry.

[0048] Step six: configure a silver nitrate solution with a concentration of 50mM with deionized water as a solvent, and put the sample prepared in step five into the silver nitrate solution, react for 6h at room temperature in the dark, and utilize the reducing property of polydopamine to reduce silver ions into nano-silver particles combined on the sample.

[0049] Step seven: rinse the sample prepared in step six with deionized water, and vacuum dry (37 DEG, 4h) through a vacuum drying box, to obtain the modified biomedical titanium alloy material.

[0050] The modified surface of the biomedical titanium alloy prepared by the method has good hydrophilicity, excellent antibacterial infection capacity and excellent bone tissue integration capacity, and can be used for bone implants and other medical devices to repair bone defects and treat postoperative bacterial infections.

[0051] As shown in Figure 1 The optical path diagram of the processing method of the application is shown.

[0052] As shown in Figure 2 The SEM diagram of the material surface prepared in the embodiment of the application is shown, from (a) figure, it can be seen that after femtosecond laser processing, the surface of the nickel-titanium alloy sample forms a groove structure which is combined with periodic corrugation; from (b) figure, it can be seen that after alkali heat treatment, the alkali heat treatment does not damage the groove structure which is combined with periodic corrugation formed by femtosecond laser processing, and rich nanosheet structure is also formed on the substrate, so that a groove-micro corrugation-nanosheet multi-level micro-nano composite structure is obtained; from (c), it can be seen that the polydopamine layer coating and the antibacterial nano-silver loading also do not damage the previous groove-micro corrugation-nanosheet multi-level micro-nano composite structure substrate, and form relatively uniform distribution of nano-particles on it.

[0053] As shown in Figure 3The surface static contact angle of the material prepared in the embodiment of the application is shown. It can be seen from the figure that the contact angle of the original polished nickel-titanium alloy surface is 74.6°, and the contact angle of the nickel-titanium alloy sample surface after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver is 12.3°, which has a strong ability to absorb water molecules and good hydrophilicity, and can provide a good interface for cell adhesion.

[0054] As shown in Figure 4 The fluorescence microscopic images of in-vitro cell live and dead tests of the modified biomedical titanium alloy material prepared in the embodiment of the application are shown, wherein (a) is the original polished nickel-titanium alloy surface; (b) is the nickel-titanium alloy sample surface after femtosecond laser processing; (c) is the nickel-titanium alloy sample surface after femtosecond laser processing and alkali heat treatment; and (d) is the nickel-titanium alloy sample surface after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver. It can be seen from the figure that the surfaces of the samples in each group are large areas of green fluorescence, and no strong red fluorescence appears, and the cells on each group of materials are basically alive, which indicates that each group of materials prepared basically has no cytotoxicity.

[0055] As shown in Figure 5 The fluorescence microscopic images of the adhesion properties of the modified biomedical titanium alloy material prepared in the embodiment of the application are shown. It can be seen from the figure that, compared with the original polished surface (a), the osteoblasts with rich pseudopods almost completely cover the nickel-titanium alloy sample surface (c) after femtosecond laser processing and alkali heat treatment and the nickel-titanium alloy sample surface (d) after femtosecond laser processing, alkali heat treatment, polydopamine layer coating and loading of antibacterial nano-silver, and the number of cells is also greatly increased compared with the original polished surface, which indicates that the modified biomedical titanium alloy material prepared in the embodiment of the application has good biological activity, can promote the adhesion and proliferation of osteoblasts, has excellent osteogenic properties and the ability to integrate with bone tissue.

[0056] As shown in Figure 6The images shown are fluorescence micrographs of Staphylococcus aureus colonization on modified biomedical titanium alloy materials prepared according to embodiments of the present invention. On the original polished surface (a), the coverage rate of live bacteria (green) was 41.6%, and the coverage rate of dead bacteria (red) was 1.9%. Live Staphylococcus aureus colonized almost the entire sample surface, with only a small number inactivated. On the surface of the nickel-titanium alloy sample after femtosecond laser processing (b), the coverage rate of live bacteria was 36.0%, and the coverage rate of dead bacteria was 1.4%. The number of Staphylococcus aureus decreased slightly. On the surface of the nickel-titanium alloy sample after femtosecond laser processing and alkaline heat treatment (c), the coverage rate of live bacteria was 24.1%, and the coverage rate of dead bacteria was 6.9%. It was observed that the number of Staphylococcus aureus was significantly reduced compared to the original surface, while the proportion of dead bacteria increased. This indicates that the multi-level micro / nano composite structure of grooves, microwave textures, and nanosheets can significantly reduce the colonization sites of Staphylococcus aureus and has a certain bactericidal ability. The surface (d) of the nickel-titanium alloy sample after femtosecond laser processing, alkaline heat treatment, polydopamine coating and loading of antibacterial nano-silver had a live bacteria coverage rate of 0.1% and a dead bacteria coverage rate of 8%, with almost no live Staphylococcus aureus colonization.

[0057] like Figure 7 The images shown are fluorescence micrographs of Escherichia coli colonization on the modified biomedical titanium alloy material prepared according to embodiments of the present invention. On the original polished surface (a), the coverage rate of live bacteria (green) is 44.7%, and the coverage rate of dead bacteria (red) is 0.5%, indicating a uniform coverage of E. coli. On the surface of the nickel-titanium alloy sample (b) after femtosecond laser processing, the coverage rate of live bacteria is 33.3%, and the coverage rate of dead bacteria is 0.8%, showing a certain reduction in the number of E. coli colonized bacteria. On the surface of the nickel-titanium alloy sample (c) after femtosecond laser processing and alkaline heat treatment, the coverage rate of live bacteria is 28.9%, and the coverage rate of dead bacteria is 0.5%, showing a significant reduction in live bacteria coverage compared to the original polished surface. This indicates that the three-level micro-nano composite structure of grooves, microwave textures, and micropores has a certain anti-E. coli colonization effect. After femtosecond laser processing, alkaline heat treatment, polydopamine coating, and loading of antibacterial nano-silver, the surface (d) of the nickel-titanium alloy sample showed a live bacteria coverage rate of 0.1% and a dead bacteria coverage rate of 5.7%, with very few Escherichia coli on the surface and almost no live Escherichia coli colonization.

[0058] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not limited to the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for surface modification of biomedical titanium alloys, characterized in that: Includes the following steps: Step 1: Ultrasonically clean and dry the polished nickel-titanium alloy material; Step 2: A femtosecond laser is vertically focused onto the surface of the nickel-titanium alloy material for processing. After processing, the material is ultrasonically cleaned and dried to obtain a nickel-titanium alloy sample with a micron-to-submicron characteristic surface structure. The specific implementation steps are as follows: (1) Load the glass slide with the clean nickel-titanium alloy material fixed onto the high-precision six-degree-of-freedom translation stage; (2) A sapphire femtosecond laser processing system was selected, a 5x processing objective lens was selected, the femtosecond laser repetition rate was set to 1000 Hz, the femtosecond laser processing power was set to 8-30 mW, the scanning speed was 500-2000 um / s, the scanning interval was 8-20 um, the focal point was processed, and after processing, it was cleaned and dried to obtain a nickel-titanium alloy sample with a micron-submicron characteristic structure surface. Step 3: Place the nickel-titanium alloy sample obtained in Step 2 into a high-temperature reactor, add alkaline solution for alkaline heat treatment, ultrasonically clean and dry to obtain a nickel-titanium alloy sample with micron-submicron-nano characteristic surface structure. The specific implementation steps are as follows: Prepare an alkaline solution with a concentration of 1-5 M composed of sodium hydroxide and deionized water. Place the alkaline solution and the nickel-titanium alloy sample with micron-submicron characteristic surface structure prepared in step two into a high-pressure reactor lined with polytetrafluoroethylene and seal it tightly. Then, place the high-pressure reactor into a muffle furnace, set the reaction temperature to 80°C, and react for 12-24 hours. After the treatment is completed, clean and dry to obtain a nickel-titanium alloy sample with micron-submicron-nano characteristic surface structure. Step 4: Place the nickel-titanium alloy sample with micron-submicron-nano characteristic surface obtained in Step 3 into an alkaline Tris buffer solution containing dopamine hydrochloride to form a polydopamine coating on it, thus obtaining a composite structure. Step 5: Place the composite structure obtained in Step 4 into a silver nitrate solution to generate silver nanoparticles on the composite structure, thus obtaining a silver-loaded composite structure; complete the surface modification.

2. The method for surface modification of biomedical titanium alloy as described in claim 1, characterized in that: The specific implementation steps of step four are as follows: Select an alkaline Tris buffer solution with a pH of 8-10 and use it as a solvent to prepare a dopamine hydrochloride solution with a concentration of 1 mg / ml-3 mg / ml; immerse the nickel-titanium alloy sample with micron-submicron-nano characteristic surface prepared in step three into the dopamine hydrochloride solution and let it stand for 12 h-24 h; after the treatment, clean and dry it.

3. The method for surface modification of biomedical titanium alloy as described in claim 1, characterized in that: The specific implementation steps of step five are as follows: prepare a silver nitrate solution with a concentration of 10 mM-50 mM, place the composite structure prepared in step four into the silver nitrate solution, and react for 1 h-12 h under light-protected conditions; after the treatment is completed, clean and dry.

4. The method for surface modification of biomedical titanium alloy as described in claim 1, characterized in that: The obtained silver-loaded composite structure was used for bone defect repair and postoperative bacterial infection control. The obtained silver-loaded composite structure has good hydrophilicity, promotes cell adhesion and proliferation, can improve the integration ability of biomedical titanium materials with bone tissue, and has antibacterial infection resistance.

5. An apparatus for implementing the method of any one of claims 1 to 4, characterized in that: include: Femtosecond laser; Continuous attenuation plate; First reflecting mirror; Second reflecting mirror; Light shutter; Third reflecting mirror; Focusing lens; Nickel-titanium alloy material to be processed; Six-DOF translation stage; dichroic mirror ； A white light source; a CCD camera and a computer; a laser generated by a femtosecond laser passes sequentially through a continuous attenuator, a first reflecting mirror, a second reflecting mirror, an optical shutter, a third reflecting mirror, and a focusing lens, and is focused onto the surface of the nickel-titanium alloy material to be processed; the computer controls the opening and closing of the optical shutter, the movement of the six-degree-of-freedom translation stage, and displays the image generated by the CCD camera; the white light generated by the white light source passes sequentially through a dichroic mirror, a third reflecting mirror, and a focusing lens to illuminate the surface of the nickel-titanium alloy material to be processed, and is then reflected sequentially along the focusing lens, the third reflecting mirror, and the dichroic mirror to the CCD camera to generate real-time imaging of the processing area.

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