Method for growing multi-functional nano-coating in-situ on surface of nickel-titanium alloy using one-step method, and use thereof

Abstract

The present application relates to the technical field of biomedical material surface treatment, and specifically relates to a method for growing a multi-functional nano-coating in situ on a surface of a nickel-titanium alloy using a one-step method, and the use thereof. The method comprises the following steps: first performing ultrasonic cleaning pre-treatment on a nickel-titanium alloy test piece, then immersing the pre-treated nickel-titanium alloy test piece in a lithium-containing reaction solution, and growing the multi-functional nano-coating in situ on the surface thereof by means of a chemical reaction. The multi-functional nano-coating prepared using the method of the present application has a nano morphology on the surface, and nickel ions and lithium ions can be regulated and controlled according to process parameters. By means of the nano morphology and the release of nickel ions and lithium ions, the nickel-titanium alloy can be endowed with excellent antibacterial properties and biological functionality. Therefore, the coating is expected to be used as a medical nickel-titanium alloy surface coating, and has a broad application prospect in the field of medical devices and biomedical engineering.

Description

A method for in-situ growth of multifunctional nano-coatings on nickel-titanium alloy surfaces in a one-step process and its application.

[0001] This application claims priority to Chinese Patent Application No. 202511696551.0, filed on November 19, 2025, entitled "A method for in-situ growth of multifunctional nano-coatings on nickel-titanium alloy surfaces in one step and its application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of biomedical material surface treatment technology, specifically to a one-step method for in-situ growth of multifunctional nano-coatings on nickel-titanium alloy surfaces and its application. Background Technology

[0003] Near-equal atomic ratio nickel-titanium alloys, with their core advantages of superelasticity, shape memory effect, and low elastic modulus, are widely used in cardiovascular stents, orthopedic implants, and minimally invasive devices. Their properties reduce stress shielding, adapt to complex physiological environments, and enable precise morphological control. However, nickel-titanium alloys lack antibacterial properties, posing a risk of bacterial infection after implantation. Furthermore, they exhibit poor biocompatibility, some cytotoxicity, and insufficient ability to promote repair after implantation.

[0004] The aforementioned issues are all closely related to the surface properties of nickel-titanium alloys; therefore, surface modification has become a key research direction for improving their clinical safety and functional integration. To this end, researchers are dedicated to endowing nickel-titanium alloys with antibacterial activity without altering the mechanical properties of the matrix, thereby further optimizing their biological response. Current mainstream strategies include: constructing an ordered TiO2 nanotube array coating on the surface through anodic oxidation. This not only improves the stability of the passivation film but can also act as a substrate for drugs or metal ions (such as Ag). + Zn 2+ Cu 2+ Sustained-release carriers can be used to achieve long-lasting antibacterial effects; polydopamine (PDA) coatings, due to their versatility, adhesiveness, and reducing properties, can serve as an intermediate layer to immobilize antibacterial molecules (such as antibiotics, chitosan, and antimicrobial peptides) and promote osteoblast adhesion, thus improving biocompatibility and anti-infection capabilities; calcium phosphate-based coatings (such as hydroxyapatite, HA) mimic bone tissue components, significantly enhancing bone integration performance, and are often used in combination with antibacterial agents to achieve a dual function of "anti-infection and promoting healing"; in addition, plasma treatment and graft polymerization can construct superhydrophilic or antifouling surfaces, reducing non-specific protein adsorption and initial bacterial adhesion. Although the above surface modification methods have partially solved the problems existing in the clinical application of medical nickel-titanium alloys, there are still problems such as cumbersome coating preparation steps, poor film-substrate adhesion, single function, and insufficient cell-promoting function.

[0005] Previous studies have found that immersing nickel-titanium alloys in NaOH alkaline solution can prepare a nickel-containing nanosheet structure coating on its surface in one step. This coating can continuously release nickel ions to exert antibacterial function, but its biocompatibility is poor, and the nanosheets in the coating have very weak bonding force with the substrate and are easy to fall off, raising concerns about its safety. Summary of the Invention

[0006] This application overcomes the shortcomings of the prior art by providing a one-step method for in-situ growth of multifunctional nano-coatings on the surface of nickel-titanium alloys. The multifunctional nano-coatings prepared by this method are expected to fundamentally solve the problems of poor adhesion between the coating film and the substrate and the single function, thereby significantly improving the safety and functionality of nickel-titanium alloys in clinical use.

[0007] To solve the above-mentioned technical problems, the technical solution adopted in this application is: a one-step method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy, comprising the following steps:

[0008] (1) The nickel-titanium alloy was pretreated by ultrasonic cleaning in acetone, anhydrous ethanol and deionized water in sequence, and then dried with cold air for later use.

[0009] (2) Prepare LiOH solution using ultrapure water;

[0010] (3) The LiOH solution and the pretreated nickel-titanium alloy were placed together into a hydrothermal reactor; the hydrothermal reactor was then placed in a hydrothermal reaction chamber for reaction.

[0011] (4) After the reaction is complete, the nickel-titanium alloy sheet is removed, ultrasonically cleaned with ultrapure water and dried to finally obtain a multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy.

[0012] As a further limitation of the technical solution of this application, the nickel-titanium alloy is a nickel-titanium alloy sheet.

[0013] As a further limitation of the technical solution of this application, the size of the nickel-titanium alloy sheet in step (1) is 10mm×10mm×1mm.

[0014] As a further limitation of the technical solution of this application, the concentration of LiOH solution in step (2) is 0.05mol / L-0.8mol / L.

[0015] As a further limitation of the technical solution of this application, the concentration of LiOH solution in step (2) is 0.1mol / L-0.4mol / L.

[0016] As a further limitation of the technical solution of this application, the concentration of LiOH solution in step (2) is 0.2 mol / L.

[0017] As a further limitation of the technical solution of this application, the reaction in step (3) is to heat the hydrothermal reaction chamber to 150℃-200℃ and keep it at that temperature for 0.5h-2h.

[0018] As a further limitation of the technical solution of this application, the reaction in step (3) is to heat the hydrothermal reaction chamber to 150℃-200℃ and keep it at that temperature for 1 hour.

[0019] The present invention also provides a multifunctional nanocoating obtained by the method described above, wherein the microstructure of the multifunctional nanocoating is polygonal nanoparticles.

[0020] As a further limitation of the technical solution of this application, the bonding force between the nickel-titanium alloy sheet and the multifunctional nano-coating is 28-45N.

[0021] This application also provides the application of the multifunctional nanocoating obtained by the above method in the preparation of medical devices and biomedical engineering.

[0022] Compared with the prior art, this application has the following advantages:

[0023] (1) The method used in this application has mild reaction conditions, simple equipment, low cost, good process repeatability, and can grow multifunctional nano-coatings in situ on the surface of nickel-titanium alloy with complex shape.

[0024] (2) The method of this application can realize the in-situ growth of coating nanostructures and the simultaneous loading of Ni and Li elements on the surface of nickel-titanium alloy in one step.

[0025] (3) The multifunctional nano-coating prepared by the method of this application consists of nanoparticles grown in situ on the surface of nickel-titanium alloy. It has high film-substrate adhesion, is not easy to fall off during implantation and service, and has good stability.

[0026] (4) The multifunctional nanocoating prepared by the method of this application can control the nanomorphology and the loading and release behavior of Ni and Li by adjusting the concentration of LiOH solution, thus making it suitable for different application scenarios.

[0027] (5) The multifunctional nanocoating prepared by the method of this application has both good antibacterial properties and biological functionality. Attached Figure Description

[0028] Figure 1 shows low-magnification (left) and high-magnification (right) scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 1 of this application;

[0029] Figure 2 shows a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.1) prepared in Example 1 of this application;

[0030] Figure 3 is a bar chart of the water contact angle of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.1) with in-situ multifunctional nano-coating prepared in Example 1 of this application;

[0031] Figure 4 is a bar chart showing the nickel ion release concentration of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.1) with in-situ multifunctional nano-coating prepared in Example 1 of this application.

[0032] Figure 5 shows optical photographs of bacterial colonies corresponding to the control group, untreated nickel-titanium alloy (NiTi), and nickel-titanium alloy (NiTi-0.1) with in-situ multifunctional nano-coating prepared in Example 1 of this application (where the left is the control group, the middle is the untreated nickel-titanium alloy (NiTi), and the right is the nickel-titanium alloy (NiTi-0.1)).

[0033] Figure 6 shows the antibacterial rates of the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy (NiTi-0.1) with an in-situ multifunctional nano-coating prepared in Example 1 of this application.

[0034] Figure 7 is a bar chart of lithium ion release concentration of the nickel-titanium alloy (NiTi-0.1) with in-situ grown multifunctional nano-coating prepared in Example 1 of this application;

[0035] Figure 8 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.1) with in-situ multifunctional nanocoatings prepared in Example 1 of this application.

[0036] Figure 9 shows low-magnification (left) and high-magnification (right) scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 2 of this application;

[0037] Figure 10 is a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.2) prepared in Example 2 of this application;

[0038] Figure 11 is a bar chart of the water contact angle of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.2) with in-situ multifunctional nano-coating prepared in Example 2 of this application;

[0039] Figure 12 is a bar chart showing the nickel ion release concentration of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.2) with in-situ multifunctional nano-coating prepared in Example 2 of this application;

[0040] Figure 13 shows optical photographs of bacterial colonies corresponding to the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy (NiTi-0.2) with an in-situ multifunctional nano-coating prepared in Example 2 of this application. (The left side is the control group, the middle side is the untreated nickel-titanium alloy (NiTi), and the right side is the nickel-titanium alloy (NiTi-0.2)).

[0041] Figure 14 shows the antibacterial rates of the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy (NiTi-0.2) with an in-situ multifunctional nano-coating prepared in Example 2 of this application.

[0042] Figure 15 is a bar chart of lithium ion release concentration of the nickel-titanium alloy (NiTi-0.2) with in-situ grown multifunctional nano-coating prepared in Example 2 of this application;

[0043] Figure 16 is a bar chart showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.2) with in-situ multifunctional nanocoatings prepared in Example 2 of this application;

[0044] Figure 17 shows low-magnification (left) and high-magnification (right) scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 3 of this application;

[0045] Figure 18 is a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.4) prepared in Example 3 of this application;

[0046] Figure 19 is a bar chart of the water contact angle of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.4) with in-situ multifunctional nano-coating prepared in Example 3 of this application;

[0047] Figure 20 is a bar chart of nickel ion release concentration for untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.4) with in-situ multifunctional nano-coating prepared in Example 3 of this application;

[0048] Figure 21 shows optical photographs of bacterial colonies corresponding to the control group, untreated nickel-titanium alloy (NiTi), and nickel-titanium alloy (NiTi-0.4) with in-situ multifunctional nano-coating prepared in Example 3 of this application (where the left is the control group, the middle is the untreated nickel-titanium alloy (NiTi), and the right is the nickel-titanium alloy (NiTi-0.4)).

[0049] Figure 22 shows the antibacterial rates of the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy (NiTi-0.4) with a multifunctional nano-coating grown in situ on the surface prepared in Example 3 of this application.

[0050] Figure 23 is a bar chart of lithium ion release concentration of the nickel-titanium alloy (NiTi-0.4) with multifunctional nano-coatings grown in situ on the surface prepared in Example 3 of this application;

[0051] Figure 24 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.4) with in-situ multifunctional nanocoatings prepared in Example 3 of this application;

[0052] Figure 25 shows low-magnification (left) and high-magnification (right) scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 4 of this application;

[0053] Figure 26 shows a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.8) prepared in Example 4 of this application;

[0054] Figure 27 is a bar chart of the water contact angle of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.8) with in-situ multifunctional nano-coating prepared in Example 4 of this application;

[0055] Figure 28 is a bar chart of nickel ion release concentration for untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.8) with in-situ multifunctional nano-coating prepared in Example 4 of this application;

[0056] Figure 29 shows optical photographs of bacterial colonies corresponding to the control group, untreated nickel-titanium alloy (NiTi), and nickel-titanium alloy (NiTi-0.8) with in-situ multifunctional nano-coating prepared in Example 4 of this application (where the left is the control group, the middle is the untreated nickel-titanium alloy (NiTi), and the right is the nickel-titanium alloy (NiTi-0.8)).

[0057] Figure 30 shows the antibacterial rates of the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy (NiTi-0.8) with a multifunctional nano-coating grown in situ on the surface prepared in Example 4 of this application.

[0058] Figure 31 is a bar chart of lithium ion release concentration of the nickel-titanium alloy (NiTi-0.8) with in-situ grown multifunctional nano-coating prepared in Example 4 of this application;

[0059] Figure 32 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy (NiTi-0.8) with in-situ multifunctional nanocoatings prepared in Example 4 of this application. Detailed Implementation

[0060] The present application will be further described below with reference to specific embodiments.

[0061] Example 1

[0062] The specific preparation method of the multifunctional nano-coating on the surface of nickel-titanium alloy is carried out according to the following steps:

[0063] (1) The nickel-titanium alloy sheet with a size of 10mm×10mm×1mm was ultrasonically cleaned and pretreated in acetone, anhydrous ethanol and deionized water in sequence, and then dried with cold air for later use.

[0064] (2) Prepare a LiOH solution containing 0.1 mol / L using ultrapure water.

[0065] (3) The prepared LiOH solution and the pretreated nickel-titanium alloy sheet were placed together into a hydrothermal reactor, and the hydrothermal reactor was then placed in a hydrothermal reaction chamber and heated to 200°C and kept at that temperature for 1 hour.

[0066] (4) After the reaction is complete, the nickel-titanium alloy sheet is removed, ultrasonically cleaned with ultrapure water and dried to finally obtain a multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy sheet.

[0067] Figure 1 shows low-magnification and high-magnification scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 1 of this application. It can be seen that the multifunctional nano-coating prepared in Example 1 of this application is relatively uniform, with a microstructure consisting of polygonal nanoparticles.

[0068] Figure 2 shows a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.1) prepared in Example 1 of this application. It can be seen that the coating has good adhesion to the substrate, reaching 28 N.

[0069] Figure 3 is a bar graph showing the water contact angles of the untreated nickel-titanium alloy and the multifunctional nanocoating prepared in Example 1 of this application. The results show that, compared with the untreated nickel-titanium alloy, the multifunctional nanocoating on the nickel-titanium alloy surface has significantly increased hydrophilicity, which is beneficial to cell adhesion and spreading.

[0070] Figure 4 is a bar chart showing the nickel ion release behavior of the untreated nickel-titanium alloy and the nickel-titanium alloy with a multifunctional nano-coating prepared in Example 1 of this application. The results show that, compared with the untreated nickel-titanium alloy, the nickel-titanium alloy with the multifunctional nano-coating grown in situ can release more nickel ions, and nickel ions have certain antibacterial properties.

[0071] Figure 5 shows optical photographs of bacterial colonies in the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy with an in-situ multifunctional nano-coating prepared in Example 1 of this application (NiTi-0.1). It can be seen that the Staphylococcus aureus bacterial colonies in the untreated nickel-titanium alloy (NiTi) group and the control group without samples are very dense and the number is not significantly different, indicating poor antibacterial activity. In contrast, the nickel-titanium alloy (NiTi-0.1) group with the in-situ multifunctional nano-coating has only a small number of bacterial colonies, indicating good antibacterial activity. Quantitative results of the antibacterial rate (Figure 6) show that the untreated nickel-titanium alloy (NiTi) group has only about 5%, while the nickel-titanium alloy (NiTi-0.1) group with the in-situ multifunctional nano-coating reaches 77%, which can be mainly attributed to the higher nickel ion release in this group. The nickel-titanium alloy (NiTi-0.1) with the in-situ multifunctional nano-coating can release not only nickel ions but also lithium ions (Figure 7), and lithium ions have the effect of promoting cell function.

[0072] Figure 8 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy with an in-situ multifunctional nanocoating prepared in Example 1 of this application (NiTi-0.1). It can be seen that the number of cells in both groups increases with increasing culture time, but the NiTi-0.1 group proliferates faster and exhibits better biological function, which can be mainly attributed to the combined effect of its nanostructure and lithium-ion release. These results demonstrate that a multifunctional nanocoating with high film-substrate adhesion, good antibacterial properties, and biofunctionality was successfully prepared on the surface of nickel-titanium alloy using the one-step method described in this embodiment.

[0073] Example 2

[0074] The specific preparation method of the multifunctional nano-coating on the surface of nickel-titanium alloy is carried out according to the following steps:

[0075] (1) The nickel-titanium alloy sheet with a size of 10mm×10mm×1mm was ultrasonically cleaned and pretreated in acetone, anhydrous ethanol and deionized water in sequence, and then dried with cold air for later use.

[0076] (2) Prepare a LiOH solution containing 0.2 mol / L using ultrapure water.

[0077] (3) Place the prepared LiOH solution and nickel-titanium alloy sheet into a hydrothermal reactor, then place the hydrothermal reactor in a hydrothermal reaction chamber and heat it to 200°C and keep it warm for 1 hour.

[0078] (4) After the reaction is complete, the nickel-titanium alloy sheet is removed, ultrasonically cleaned with ultrapure water and dried to finally obtain a multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy sheet.

[0079] Figure 9 shows low-magnification and high-magnification scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 2 of this application. It can be seen that the multifunctional nano-coating prepared in Example 2 of this application is relatively uniform, with a microstructure consisting of polygonal nanoparticles.

[0080] Figure 10 shows a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.2) prepared in Example 2 of this application. It can be seen that the coating has good adhesion to the substrate, reaching 34 N.

[0081] Figure 11 is a bar graph showing the water contact angles of the untreated nickel-titanium alloy and the multifunctional nanocoating prepared in Example 2 of this application. The results show that, compared with the untreated nickel-titanium alloy, the multifunctional nanocoating on the nickel-titanium alloy surface has significantly increased hydrophilicity, which is beneficial to cell adhesion and spreading.

[0082] Figure 12 is a bar chart showing the nickel ion release behavior of the untreated nickel-titanium alloy and the nickel-titanium alloy with a multifunctional nanocoating prepared in Example 2 of this application. The results show that, compared with the untreated nickel-titanium alloy, the nickel-titanium alloy with the multifunctional nanocoating grown in situ can release more nickel ions, and nickel ions have certain antibacterial properties.

[0083] Figure 13 shows optical photographs of bacterial colonies in the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy with an in-situ multifunctional nano-coating prepared in Example 2 of this application (NiTi-0.2). It can be seen that the Staphylococcus aureus bacterial colonies in the untreated nickel-titanium alloy (NiTi) group and the control group (without sample) are very dense and the number is not significantly different, indicating poor antibacterial properties. In contrast, the nickel-titanium alloy (NiTi-0.2) group with the in-situ multifunctional nano-coating has only a small number of bacterial colonies, indicating good antibacterial properties.

[0084] The quantitative results of the antibacterial rate (Figure 14) show that the untreated nickel-titanium alloy (NiTi) group only achieved about 5%, while the nickel-titanium alloy (NiTi-0.2) group with in-situ grown multifunctional nano-coatings reached 84%, which can be mainly attributed to the higher nickel ion release of this group. The nickel-titanium alloy (NiTi-0.2) with in-situ grown multifunctional nano-coatings can release not only nickel ions but also lithium ions (Figure 15), and lithium ions have the effect of promoting cell function.

[0085] Figure 16 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy with an in-situ multifunctional nanocoating prepared in Example 2 of this application (NiTi-0.2). It can be seen that the number of cells in both groups increases with increasing culture time, but the NiTi-0.2 group proliferates faster and exhibits better biological function, which can be mainly attributed to the combined effect of its nanostructure and lithium-ion release. These results demonstrate that a multifunctional nanocoating with high film-substrate adhesion, good antibacterial properties, and biofunctionality was successfully prepared on the surface of nickel-titanium alloy using the one-step method described in this embodiment.

[0086] Example 3

[0087] The specific preparation method of the multifunctional nano-coating on the surface of nickel-titanium alloy is carried out according to the following steps:

[0088] (1) Clean the nickel-titanium alloy sheet with a size of 10mm×10mm×1mm in acetone, anhydrous ethanol and deionized water by ultrasonic cleaning in sequence, and dry it with cold air for later use.

[0089] (2) Prepare a LiOH solution containing 0.4 mol / L using ultrapure water.

[0090] (3) Place the prepared LiOH solution and nickel-titanium alloy sheet into a hydrothermal reactor, then place the reactor in a hydrothermal reaction chamber and heat it to 200°C and keep it warm for 1 hour.

[0091] (4) After the reaction is complete, the nickel-titanium alloy sheet is removed, ultrasonically cleaned with ultrapure water and dried to finally obtain a multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy.

[0092] Figure 17 shows low-magnification and high-magnification scanning electron microscope images of the multifunctional nano-coating on the surface of the nickel-titanium alloy prepared in Example 3 of this application. It can be seen that the multifunctional nano-coating prepared in Example 3 of this application is relatively uniform, with a microstructure consisting of polygonal nanoparticles.

[0093] Figure 18 shows a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.4) prepared in Example 3 of this application. It can be seen that the coating has good adhesion to the substrate, reaching 45 N.

[0094] Figure 19 is a bar graph showing the water contact angles of the untreated nickel-titanium alloy and the multifunctional nanocoating prepared in Example 3 of this application. The results show that, compared with the untreated nickel-titanium alloy, the multifunctional nanocoating on the nickel-titanium alloy surface has significantly increased hydrophilicity, which is beneficial to cell adhesion and spreading.

[0095] Figure 20 is a bar chart showing the nickel ion release behavior of the untreated nickel-titanium alloy and the nickel-titanium alloy with a multifunctional nanocoating prepared in Example 3 of this application. The results show that, compared with the untreated nickel-titanium alloy, the nickel-titanium alloy with the multifunctional nanocoating grown in situ can release more nickel ions, and nickel ions have certain antibacterial properties.

[0096] Figure 21 shows optical photographs of bacterial colonies in the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy (NiTi-0.4) with an in-situ multifunctional nano-coating prepared in Example 3 of this application. It can be seen that the Staphylococcus aureus bacterial colonies in the untreated nickel-titanium alloy (NiTi) group and the control group without samples are very dense and the number is not significantly different, indicating poor antibacterial activity. In contrast, the nickel-titanium alloy (NiTi-0.4) group with the in-situ multifunctional nano-coating has only a small number of bacterial colonies, indicating good antibacterial activity. Quantitative results of the antibacterial rate (Figure 22) show that the untreated nickel-titanium alloy (NiTi) group has only about 5%, while the nickel-titanium alloy (NiTi-0.4) group with the in-situ multifunctional nano-coating reaches 23%, which can be mainly attributed to the higher nickel ion release in this group. The nickel-titanium alloy (NiTi-0.4) with the in-situ multifunctional nano-coating can release not only nickel ions but also lithium ions (Figure 23), and lithium ions have the effect of promoting cell function.

[0097] Figure 24 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy with an in-situ multifunctional nanocoating prepared in Example 3 of this application (NiTi-0.4). It can be seen that the number of cells in both groups increases with increasing culture time, but the NiTi-0.4 group proliferates faster and exhibits better biological function, which can be mainly attributed to the combined effect of its nanostructure and lithium-ion release. These results demonstrate that a multifunctional nanocoating with high film-substrate adhesion, good antibacterial properties, and biofunctionality was successfully prepared on the surface of nickel-titanium alloy using the one-step method described in this embodiment.

[0098] Example 4

[0099] The specific preparation method of the multifunctional nano-coating on the surface of nickel-titanium alloy is carried out according to the following steps:

[0100] (1) Clean the nickel-titanium alloy sheet with a size of 10mm×10mm×1mm in acetone, anhydrous ethanol and deionized water by ultrasonic cleaning in sequence, and dry it with cold air for later use.

[0101] (2) Prepare a LiOH solution containing 0.8 mol / L using ultrapure water.

[0102] (3) Place the prepared LiOH solution and nickel-titanium alloy sheet into a hydrothermal reactor, then place the reactor in a hydrothermal reaction chamber and heat it to 200°C and keep it warm for 1 hour.

[0103] (4) After the reaction is complete, the nickel-titanium alloy sheet is removed, ultrasonically cleaned with ultrapure water and dried to finally obtain a multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy.

[0104] Figure 25 shows low-magnification and high-magnification scanning electron microscope images of the multifunctional nano-coating on the nickel-titanium alloy surface prepared in Example 4 of this application. It can be seen that the multifunctional nano-coating prepared in Example 4 of this application is relatively uniform, with a microstructure consisting of polygonal nanoparticles.

[0105] Figure 26 shows a scratch photograph of the multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy (NiTi-0.8) prepared in Example 4 of this application. It can be seen that the coating has good adhesion to the substrate, reaching 42 N.

[0106] Figure 27 is a bar chart showing the water contact angles of the untreated nickel-titanium alloy and the multifunctional nanocoating prepared in Example 4 of this application. The results show that, compared with the untreated nickel-titanium alloy, the multifunctional nanocoating on the nickel-titanium alloy surface has significantly increased hydrophilicity, which is beneficial to cell adhesion and spreading.

[0107] Figure 28 is a bar chart showing the nickel ion release behavior of the untreated nickel-titanium alloy and the nickel-titanium alloy with a multifunctional nanocoating prepared in Example 4 of this application. The results show that, compared with the untreated nickel-titanium alloy, the nickel-titanium alloy with the multifunctional nanocoating grown in situ can release more nickel ions, and nickel ions have certain antibacterial properties.

[0108] Figure 29 shows optical photographs of bacterial colonies in the control group, the untreated nickel-titanium alloy (NiTi), and the nickel-titanium alloy with an in-situ multifunctional nano-coating prepared in Example 4 of this application (NiTi-0.8). It can be seen that the Staphylococcus aureus bacterial colonies in the untreated nickel-titanium alloy (NiTi) group and the control group without samples are very dense and the number is not significantly different, indicating poor antibacterial activity. In contrast, the nickel-titanium alloy (NiTi-0.8) group with the in-situ multifunctional nano-coating has only a small number of bacterial colonies, indicating good antibacterial activity. Quantitative results of the antibacterial rate (Figure 30) show that the untreated nickel-titanium alloy (NiTi) group has only about 5%, while the nickel-titanium alloy (NiTi-0.4) group with the in-situ multifunctional nano-coating reaches 29%, which can be mainly attributed to the higher nickel ion release in this group. The nickel-titanium alloy (NiTi-0.8) with the in-situ multifunctional nano-coating can release not only nickel ions but also lithium ions (Figure 31), and lithium ions have the effect of promoting cell function.

[0109] Figure 32 is a bar graph showing the proliferation of osteoblasts cultured on the surfaces of untreated nickel-titanium alloy (NiTi) and nickel-titanium alloy with an in-situ multifunctional nanocoating prepared in Example 4 of this application (NiTi-0.8). It can be seen that the number of cells in both groups increases with increasing culture time, but the NiTi-0.8 group proliferates faster and exhibits better biological function, which can be mainly attributed to the combined effect of its nanostructure and lithium-ion release. These results demonstrate that a multifunctional nanocoating with high film-substrate adhesion, good antibacterial properties, and biofunctionality was successfully prepared on the surface of nickel-titanium alloy using the one-step method described in this embodiment.

[0110] The above specific embodiments employ a one-step method to grow a multifunctional nano-coating in situ on the surface of a nickel-titanium alloy. The preparation method is simple, easy to implement, low in cost, consumes few resources, and is easy to carry out, thus having a very broad application prospect.

[0111] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific embodiments of this application to these. All technical solutions formed through substitution or equivalent transformation are within the scope of protection of this application.

Claims

1. A method for growing multifunctional nanocoating on the surface of nickel-titanium alloy in situ in one step, characterized in that, Includes the following steps: (1) The nickel-titanium alloy was pretreated by ultrasonic cleaning in acetone, anhydrous ethanol and deionized water in sequence, and then dried with cold air for later use. (2) Prepare LiOH solution using ultrapure water; (3) The LiOH solution and the pretreated nickel-titanium alloy were placed together into a hydrothermal reactor; the hydrothermal reactor was then placed in a hydrothermal reaction chamber for reaction. (4) After the reaction is complete, the nickel-titanium alloy is removed, ultrasonically cleaned with ultrapure water and dried to finally obtain a multifunctional nano-coating grown in situ on the surface of the nickel-titanium alloy.

2. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy in a one-step process according to claim 1, characterized in that, The nickel-titanium alloy is a nickel-titanium alloy sheet.

3. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy in a one-step manner according to claim 2, characterized in that, In step (1), the size of the nickel-titanium alloy sheet is 10mm×10mm×1mm.

4. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy in a one-step process according to claim 1, characterized in that, In step (2), the concentration of the LiOH solution is 0.05 mol / L-0.8 mol / L.

5. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy in a one-step process according to claim 1, characterized in that, In step (2), the concentration of the LiOH solution is 0.1 mol / L-0.4 mol / L.

6. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy in a one-step manner according to claim 1, characterized in that, In step (2), the concentration of the LiOH solution is 0.2 mol / L.

7. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy using a one-step method according to claim 1, characterized in that, The reaction described in step (3) is to heat the hydrothermal reaction chamber to 150℃-200℃ and keep it at that temperature for 0.5h-2h.

8. The method for in-situ growth of a multifunctional nano-coating on the surface of a nickel-titanium alloy in a one-step process according to claim 1, characterized in that, The reaction described in step (3) is to heat the hydrothermal reaction chamber to 150℃-200℃ and keep it at that temperature for 1 hour.

9. The multifunctional nanocoating obtained by the method according to any one of claims 1-8, characterized in that, The microstructure of the multifunctional nanocoating consists of polygonal nanoparticles, and its elemental composition includes Ni and Li elements.

10. The multifunctional nanocoating according to claim 9, characterized in that, The bonding force between the nickel-titanium alloy and the multifunctional nano-coating is 28–45 N.

11. The application of the multifunctional nanocoating obtained by the method according to any one of claims 1-7 in the preparation of medical devices and biomedical engineering.

Images