Preparation method and application of titanium alloy surface antibacterial nano-enzyme coating

Abstract

The invention discloses a preparation method and application of an antibacterial nano-enzyme coating on the surface of a titanium alloy, and relates to a modification method and application of the surface of the titanium alloy. The invention aims to solve the problem of nano-enzyme activity reduction caused by a shielding effect of a resin primer on nano-enzyme active sites in a traditional nano-enzyme immobilization method. A porous ceramic coating is prepared on the surface of a titanium alloy through a plasma electrolytic oxidation technology, active groups and a nano structure are generated on the surface of the porous ceramic coating through alkali heat treatment, and cerium-based nano enzyme UiO-66 (Ce) with high HPO activity and high binding force grows and is constructed on the surface of the titanium alloy porous ceramic coating in situ; according to the PEO / UiO-66 (Ce) integral coating prepared in an in-situ growth mode, due to the fact that UiO-66 (Ce) nano enzyme directly grows on the surface in situ, active sites can be fully exposed in a water environment, and Br <-> and H2O2 can easily enter the active sites to trigger a catalytic reaction to generate HOBr.

Description

Technical Field

[0001] The present invention relates to a surface modification method and application of a titanium alloy. Background Art

[0002] Titanium alloys are known as "marine metals" due to their many excellent properties such as high strength, light weight, high toughness, and seawater corrosion resistance. They are widely used in fields such as shipbuilding, nuclear submarines, and seawater desalination, and are one of the new key materials in the marine engineering field. However, compared with other metal materials, because there is a dense TiO 2 film on the surface of titanium alloys, it has good biocompatibility, and almost all marine organisms can attach to its surface, resulting in serious biofouling problems. Marine biofouling not only increases the ship's navigation resistance and fuel consumption, but also causes pipeline blockages, affects the functions of underwater equipment, and reduces the service life of equipment. Biofouling has become a worldwide problem. According to the evolution law of biofouling, some studies have shown that by inhibiting the initial adhesion of bacteria and controlling the formation of biofilms, the subsequent attachment of large organisms will be significantly reduced, thereby directly inhibiting biofouling in the initial stage. Therefore, constructing a functional coating with antibacterial properties on the surface of titanium alloys to inhibit the formation of biofouling is of great significance for the development of marine equipment. Currently, the most economical, simple, and effective method is to apply antifouling coatings on the material surface, and release toxic substances to drive away or kill the organisms attached to the material surface to achieve the purpose of antifouling, such as antifouling agent release coatings like cuprous oxide and tributyltin, and organotin self-polishing coatings. However, these coatings lack specificity, show high toxicity to non-target marine organisms, and the continuous release of antifouling agents causes serious damage to the marine environment. In addition, research reports show that marine organisms will develop resistance after long-term use of copper-based antibacterial materials for antifouling. Ecological environment problems and strict legislation have gradually prohibited these coatings globally. Therefore, developing new antifouling coatings with broad-spectrum antifouling ability and strong environmental adaptability is of extremely high significance.

[0003] In recent years, inspired by the antifouling strategy of vanadium haloperoxidase secreted by large marine algae against the attachment of antifouling organisms on their surfaces, the antifouling strategy based on nanozymes has attracted extensive attention from domestic and foreign scholars with its significant advantages of being more efficient, green, and environmentally friendly. Among them, haloperoxidase (HPO) catalyzes Br 2 O 2 in seawater to the corresponding hypobromous acid (HOBr) in the presence of trace H - . HOBr inhibits the attachment of bacteria on the material surface by selectively destroying proteins in the bacterial membrane and halogenating bacterial signaling molecules to quench quorum sensing and block intercellular communication between bacterial cells. Currently, a variety of nanozymes have been developed, such as CeO 2-x nanorods, NL-NiMoS 2, A variety of nanomaterials with haloperoxidase activity, such as W-UiO, are used in antibacterial and anti-biofouling research. Among them, cerium-based MOFs have been proven to have excellent HPO performance and show promise in preventing biofilm formation. Although nanozymes with HPO activity show great research prospects in antibacterial and anti-marine biofouling, existing studies usually use resin as a dispersion medium to immobilize nanozymes on the surface of substrates, and this method has significant limitations. Since the HPO catalytic reaction of cerium-based nanozymes mainly occurs on their surface, and their activity depends on hydrophilic small molecules H 2 O 2 and Br- diffusing to the surface active sites and undergoing charge transfer with them to generate HOBr, the interfacial structure formed after mixing with resin seriously hinders this key charge transfer process and weakens the catalytic activity of nanozymes. In addition, the coverage of resin base materials will hinder the outward diffusion of HOBr, further limiting the exertion of enzyme activity. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of reduced activity of nanozymes caused by the shielding effect of resin primers on the active sites of nanozymes in traditional nanozyme immobilization methods, and to provide a preparation method and application of an antibacterial nanozyme coating on the surface of titanium alloy.

[0005] Compared with the traditional method of dispersing nanozymes in resin, in-situ constructing an integral nanozyme coating on the surface of the substrate can more effectively maintain the activity and reaction efficiency of nanozymes, thereby efficiently exerting antibacterial and antifouling properties.

[0006] A preparation method of an antibacterial nanozyme coating on the surface of titanium alloy is specifically completed according to the following steps:

[0007] I. Pretreatment of titanium alloy:

[0008] Use sandpaper to polish the titanium alloy, and then wash it to remove the oil stain on the surface, obtaining the pretreated titanium alloy;

[0009] II. Preparation of electrolyte:

[0010] Dissolve Na 2 SiO 3 ·9H 2 O, Na 6 O 18 P 6 , (NaPO 3 ) n and NaOH in deionized water to obtain the electrolyte;

[0011] III. Connect the positive electrode of the power supply of the plasma electrolytic oxidation equipment to the pretreated titanium alloy, and connect the negative electrode to the stainless steel electrolytic cell. Pour the electrolyte into the stainless steel electrolytic cell and continuously stir it. Immerse the pretreated titanium alloy into the electrolyte, and react for a period of time under the conditions of a current density of 6 A / cm 2 ~10 A / cm 2 , a duty cycle of 20% - 50% and a frequency of 500 Hz - 1000 Hz. After the reaction ends, take out the titanium alloy, wash it with deionized water, and then dry it to obtain a titanium alloy containing a titanium oxide ceramic transition layer;

[0012] IV. Immerse the titanium alloy containing the titanium oxide ceramic transition layer into a NaOH solution at a temperature of 60°C - 80°C for etching for a period of time. After the etching ends, take out the titanium alloy, wash it with deionized water, and then dry it to obtain a titanium alloy with a nanostructure on its surface; V.

[0014] ①. Dissolve (NH 4 ) 2 Ce(NO 3 ) 6 in deionized water to obtain a solution of (NH 4 ) 2 Ce(NO 3 ) 6 ;

[0015] ②. Dissolve terephthalic acid in N,N-dimethylformamide to obtain a terephthalic acid solution;

[0016] ③. Immerse the titanium alloy with a nanostructure on its surface into the solution of (NH 4 ) 2 Ce(NO 3 ) 6 for a period of time, and then drop the terephthalic acid solution into the solution of (NH 4 ) 2 Ce(NO 3 ) 6 to complex terephthalic acid with Ce 4+ on the surface of the titanium alloy;

[0017] VI. Transfer the mixed system in step V③ to a reaction kettle, where the titanium alloy is placed obliquely in the reaction kettle at an angle of 45 degrees, and carry out a hydrothermal reaction at 100°C - 150°C for a period of time. After cooling to room temperature, take out the titanium alloy, and then wash and dry the titanium alloy to obtain a titanium alloy with an antibacterial nanozyme coating on its surface.

[0018] The principle of the present invention:

[0019] I. The present invention proposes to prepare a porous ceramic coating on the surface of a titanium alloy through plasma electrolytic oxidation technology (PEO), and then to generate active groups and nanostructures on the surface of the porous ceramic coating through alkali heat treatment, and finally to in-situ grow and construct a cerium-based nanozyme UiO-66(Ce) with high HPO activity and high binding force on the surface of the titanium alloy porous ceramic coating; due to the in-situ growth of UiO-66(Ce) nanozyme directly on the surface of the PEO / UiO-66(Ce) monolithic coating prepared by the in-situ growth method, the active sites can be fully exposed to the water environment, and Br - and H 2 O 2 can easily enter the active sites to trigger a catalytic reaction to generate HOBr; in addition, the porous structure of the PEO coating can provide more growth sites to grow more nanozymes per unit area. The synergistic effect of the excellent intrinsic peroxidase-like activity of UiO-66(Ce) nanozyme and the structural advantages of in-situ growth endows the PEO / UiO-66(Ce) monolithic coating with good haloperoxidase activity and antibacterial properties;

[0020] II. The porous ceramic coating prepared on the surface of the titanium alloy by the PEO technology is mainly composed of TiO 2 and amorphous SiO 2 . During the etching process, TiO 2 and SiO 2 on the coating surface will be attacked by OH - in the alkali solution and undergo the following reactions:

[0021] TiO 2 +OH - →HTiO 2 -

[0022] SiO 2 +NaOH+H 2 O→NaSiO 3 +2H 2

[0023] During this process, a large number of active groups are generated on the coating surface, and due to the etching of TiO 2 and SiO 2 on the coating surface, a large number of nanostructures are generated. The active groups generated on the coating surface are used to adsorb Ce 4+ in the subsequent hydrothermal solvent, enabling the in-situ growth of UiO-66(Ce) nanozyme on its surface. The nanostructures play a certain role in confining the growth of UiO-66(Ce) nanozyme, avoiding its aggregated and stacked growth, and maximizing the exposure of active sites.

[0024] Advantages of the present invention:

[0025] The present invention provides a preparation method for in-situ constructing nanozymes with haloperoxidase (HPO) activity on the surface of titanium alloys and their application in the fields of antibacterial and anti-biofouling. TA1 is used as the substrate, and a porous ceramic coating is prepared on the surface of TA1 by the PEO technique. Then, the PEO coating is etched in a sodium hydroxide solution to activate its surface to generate active groups and microstructures. Finally, UiO-66(Ce) nanozymes with high binding strength and high HPO activity are in-situ constructed on the etched porous surface. The in-situ growth of nanozymes on the surface of titanium alloys avoids the shielding effect of the resin binder on the active sites of nanozymes in the traditional coating method, and fully exerts the HPO activity to generate a large amount of hypobromous acid to inhibit bacteria and fouling organisms. Its advantages are as follows:

[0026] (1). Metal-organic frameworks (MOFs) are ideal enzyme mimics. As a cerium-based MOF, UiO-66(Ce) has a primary and secondary coordination environment similar to that of natural enzymes and has high HPO activity, which can be used to simulate natural vanadium haloperoxidase and can catalyze Br - and H 2 O 2 to generate HOBr, having good catalytic antibacterial ability, and also having the advantages of being green, efficient, stable, and low-cost;

[0027] (2). The porous ceramic coating is prepared on TA1 by the PEO technique, and its surface is activated by alkali heat treatment to generate nanostructures. As a transition layer, on the one hand, it further improves the corrosion resistance of TA1 and the binding strength between the overall coating and the substrate, and on the other hand, the active groups and microstructures on the surface provide active sites for the in-situ growth of UiO-66(Ce) nanozymes;

[0028] (3). The in-situ construction of UiO-66(Ce) nanozymes on the surface of TA1 maximally exerts the HPO activity of UiO-66(Ce) on the basis of ensuring high binding strength, fully exposes the catalytic active sites to enable direct interaction and efficient charge transfer between the nanozymes and the substrates, and generates a large amount of hypobromous acid to inhibit bacteria and fouling organisms. Description of the Drawings

[0029] Figure 1 XRD patterns of the titanium alloy containing a titanium oxide ceramic transition layer, the titanium alloy with nanostructures on the surface, and the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0030] Figure 2 Infrared spectra of the titanium alloy containing a titanium oxide ceramic transition layer, the titanium alloy with nanostructures on the surface, and the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0031] Figure 3SEM images of the titanium alloy with a titanium oxide ceramic transition layer, the titanium alloy with a nanostructured surface, and the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0032] Figure 4 Cross-sectional SEM image and EDS surface scan spectrum of the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0033] Figure 5 XPS spectrum of the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0034] Figure 6 HPO activity test chart of the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0035] Figure 7 HPO activity cycle stability chart of the titanium alloy with an antibacterial nanozyme coating prepared in Example 1. Figure 7 The left figure in the middle is the absorbance change chart at a wavelength of 432 nm, indicating the degradation cycle performance of phenol red; the right figure is the absorbance change chart at a wavelength of 590 nm, indicating the generation cycle performance chart of bromophenol blue;

[0036] Figure 8 Performance chart of the degradation of celestine blue using the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0037] Figure 9 Antibacterial performance chart;

[0038] Figure 10 HPO activity test chart of the titanium alloy with an antibacterial nanozyme coating prepared in Example 1 and the coating after dispersion of the traditional resin prepared in Comparative Example 1;

[0039] Figure 11 HPO activity test chart of the titanium alloy with an antibacterial nanozyme coating prepared in Example 1 and the PEO titanium oxide coating. Detailed implementation method

[0040] Detailed implementation method 1: This implementation method is a preparation method for an antibacterial nanozyme coating on the surface of a titanium alloy, and is specifically completed according to the following steps:

[0041] I. Pretreatment of the titanium alloy:

[0042] Use sandpaper to polish the titanium alloy, and then wash it to remove the oil stain on the surface to obtain the pretreated titanium alloy;

[0043] II. Preparation of the electrolyte:

[0044] Dissolve Na 2 SiO3 ·9H 2 O, Na 6 O 18 P 6 , (NaPO 3 ) n and NaOH are dissolved in deionized water to obtain an electrolyte solution;

[0045] III. Connect the positive electrode of the plasma electrolytic oxidation equipment power supply to the pretreated titanium alloy, and the negative electrode to the stainless steel electrolytic cell. Pour the electrolyte solution into the stainless steel electrolytic cell and stir continuously. Immerse the pretreated titanium alloy into the electrolyte solution. React for a period of time under the conditions of a current density of 6 A / cm 2 ~10 A / cm 2 , a duty cycle of 20% - 50% and a frequency of 500 Hz - 1000 Hz. After the reaction is completed, take out the titanium alloy, wash it with deionized water, and then dry it to obtain a titanium alloy with a titanium oxide ceramic transition layer;

[0046] IV. Immerse the titanium alloy with a titanium oxide ceramic transition layer into a NaOH solution at a temperature of 60°C - 80°C for etching for a period of time. After the etching is completed, take out the titanium alloy, wash it with deionized water, and then dry it to obtain a titanium alloy with nanostructures on its surface; V.

[0048] ①. Dissolve (NH 4 ) 2 Ce(NO 3 ) 6 in deionized water to obtain a (NH 4 ) 2 Ce(NO 3 ) 6 solution;

[0049] ②. Dissolve terephthalic acid in N,N-dimethylformamide to obtain a terephthalic acid solution;

[0050] ③. Immerse the titanium alloy with nanostructures on its surface into the (NH 4 ) 2 Ce(NO 3 ) 6 solution for a period of time, and then drip the terephthalic acid solution into the (NH 4 ) 2 Ce(NO 3 ) 6 solution to complex terephthalic acid with Ce 4+ on the surface of the titanium alloy;

[0051] VI. Transfer the mixed system in Step 5(3) into a reaction kettle, where the titanium alloy is placed obliquely in the reaction kettle at an angle of 45 degrees, and hydrothermally react for a period of time at 100°C to 150°C. After cooling to room temperature, take out the titanium alloy, and then clean and dry the titanium alloy to obtain a titanium alloy with an antibacterial nanozyme coating on its surface.

[0052] The present invention combines the PEO technology and the chemical etching method to in-situ grow and construct a nanozyme coating (i.e., antibacterial nanozyme coating) loaded with UiO-66(Ce) on the surface of the titanium alloy, realizing the continuous and uniform growth of UiO-66(Ce) enzyme with high HPO activity on the surface of the titanium alloy. The porous ceramic coating prepared by PEO on the surface of the titanium alloy serves as a transition layer, which on the one hand further improves the corrosion resistance of the titanium alloy, and on the other hand, the active groups and nanostructures generated on the surface of the porous ceramic coating after alkali etching provide nucleation sites for the in-situ growth of UiO-66(Ce), enabling UiO-66(Ce) to grow continuously and uniformly on the surface of the porous ceramic and firmly fixing the nanozyme on the coating surface through the electrostatic adsorption of surface active groups and the mechanical "interlocking" mechanism of nanostructures, giving full play to the HPO activity of the UiO-66(Ce) nanozyme and avoiding the adverse effects of using traditional coating resins on the active sites of the nanozyme. This method has good inspiration and reference significance for the in-situ construction and design of other nanozymes on the material surface and has good application prospects.

[0053] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that in Step 1, the titanium alloy is polished successively with 600#, 800#, 1200#, and 1500# sandpapers; the cleaning in Step 1 is carried out successively with absolute ethanol and acetone. Other steps are the same as those in Specific Embodiment 1.

[0054] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is that the titanium alloy in Step 1 is TA1, TA2, or TC4. Other steps are the same as those in Specific Embodiment 1 or 2.

[0055] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is that the concentration of Na 2 SiO 3 ·9H 2 O in the electrolyte in Step 2 is 15 g / L to 20 g / L, the concentration of Na 6 O 18 P 6 is 6 g / L to 10 g / L, the concentration of (NaPO 3 ) n is 2 g / L to 4 g / L, and the concentration of NaOH is 6 g / L to 8 g / L. Other steps are the same as those in Specific Embodiments 1 to 3.

[0056] Embodiment 5: The difference between this embodiment and any one of Embodiments 1 to 4 is that: the reaction time in Step 3 is 10 min to 20 min; after the reaction in Step 3 ends, the titanium alloy is taken out and washed 3 to 5 times with deionized water to obtain a titanium alloy with a titanium oxide ceramic transition layer. Other steps are the same as those in Embodiments 1 to 4.

[0057] Embodiment 6: The difference between this embodiment and any one of Embodiments 1 to 5 is that: the concentration of the NaOH solution in Step 4 is 1 mol / L to 3 mol / L; the etching time in Step 4 is 6 h to 24 h. Other steps are the same as those in Embodiments 1 to 5.

[0058] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is that: after the etching in Step 4 ends, the titanium alloy is taken out, washed 3 to 5 times with deionized water, and then dried at 60 °C to 80 °C for 6 h to 12 h to obtain a titanium alloy with nanostructures on its surface. Other steps are the same as those in Embodiments 1 to 6.

[0059] Embodiment 8: The difference between this embodiment and any one of Embodiments 1 to 7 is that: in Step 5①, the mass ratio of (NH 4 ) 2 Ce(NO 3 ) 6 to the volume of deionized water is (3 g to 4 g):(10 mL to 15 mL); in Step 5②, the mass ratio of terephthalic acid to the volume of N,N-dimethylformamide is (1 g to 1.1 g):(20 mL to 30 mL); in Step 5③, the volume ratio of the (NH 4 ) 2 Ce(NO 3 ) 6 solution to the terephthalic acid solution is (10 mL to 15 mL):(20 mL to 30 mL); the soaking time in Step 5③ is 3 h to 6 h. Other steps are the same as those in Embodiments 1 to 7.

[0060] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is that: the hydrothermal reaction time in Step 6 is 2 h to 6 h; in Step 6, the titanium alloy is washed 2 to 4 times with deionized water, absolute ethanol, and acetone in sequence; the drying temperature in Step 6 is 60 °C to 80 °C, and the drying time is 6 h to 12 h. Other steps are the same as those in Embodiments 1 to 8.

[0061] Embodiment 10: This embodiment is an application of a titanium alloy surface antibacterial nanozyme coating in the field of marine antifouling.

[0062] The beneficial effects of the present invention are verified by the following examples:

[0063] Example 1: A preparation method of an antibacterial nanozyme coating on the surface of a titanium alloy, which is specifically completed according to the following steps:

[0064] I. Pretreatment of the titanium alloy:

[0065] The titanium alloy is polished successively with 600#, 800#, 1200#, and 1500# sandpapers, and then washed successively with absolute ethanol and acetone to remove the oil stains on the surface of the titanium alloy, obtaining the pretreated titanium alloy;

[0066] The titanium alloy described in step I is TA1;

[0067] II. Preparation of the electrolyte:

[0068] Dissolve Na 2 SiO 3 ·9H 2 O, Na 6 O 18 P 6 , (NaPO 3 ) n and NaOH in deionized water to obtain the electrolyte;

[0069] In the electrolyte described in step II, the concentration of Na 2 SiO 3 ·9H 2 O is 15 g / L, the concentration of Na 6 O 18 P 6 is 6 g / L, the concentration of (NaPO 3 ) n is 2 g / L, and the concentration of NaOH is 6 g / L;

[0070] III. Connect the positive electrode of the plasma electrolytic oxidation equipment power supply to the pretreated titanium alloy, and the negative electrode to the stainless steel electrolytic cell. Pour the electrolyte into the stainless steel electrolytic cell and stir continuously. Immerse the pretreated titanium alloy into the electrolyte, and react for 10 min under the conditions of a current density of 6 A / cm 2 , a duty cycle of 20%, and a frequency of 1000 Hz. After the reaction, take out the titanium alloy, wash it 3 times with deionized water, and then dry it at 60 °C for 12 h to obtain a titanium alloy (PEO) with a titanium oxide ceramic transition layer;

[0071] IV. Immerse the titanium alloy with a titanium oxide ceramic transition layer into a NaOH solution at a temperature of 60 °C for 12 h. After the etching is completed, take out the titanium alloy, wash it 3 times with deionized water, and then dry it at 60 °C for 8 h to obtain a titanium alloy with nanostructures on its surface (PEO-Etch);

[0072] In step IV, the concentration of the NaOH solution is 3 mol / L; V.

[0074] ① Dissolve 3.506 g of (NH 4 ) 2 Ce(NO 3 ) 6 in 12 mL of deionized water to obtain a solution of (NH 4 ) 2 Ce(NO 3 ) 6 ;

[0075] ② Dissolve 1.062 g of terephthalic acid in 24 mL of N,N-dimethylformamide to obtain a terephthalic acid solution;

[0076] ③ Immerse the titanium alloy with nanostructures on its surface into the solution of (NH 4 ) 2 Ce(NO 3 ) 6 for 3 h, and then add the terephthalic acid solution dropwise to the solution of (NH 4 ) 2 Ce(NO 3 ) 6 to complex the terephthalic acid with Ce on the surface of the titanium alloy; 4+

[0077] VI. Transfer the mixed system in step V③ to a reaction kettle, where the titanium alloy is placed obliquely in the reaction kettle at an angle of 45 degrees, and hydrothermally react at 100 °C for a period of 3 h. After cooling to room temperature, take out the titanium alloy, wash it 3 times with deionized water, absolute ethanol, and acetone respectively, and then dry it at 60 °C for 12 h to obtain a titanium alloy with an antibacterial nanozyme coating on its surface (PEO / UiO-66(Ce)).

[0078] Figure 1 XRD patterns of the titanium alloy with a titanium oxide ceramic transition layer, the titanium alloy with nanostructures on its surface, and the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0079] As can be seen from Figure 1 : The titanium alloy with an antibacterial nanozyme coating prepared in Example 1 (PEO / UiO-66(Ce)) is composed of titanium and titanium oxide, where the titanium oxide includes rutile TiO​2 and anatase TiO 2 The XRD pattern of PEO / UiO-66(Ce) shows sharp reflections near 7.3°, 8.2°, 11.6°, 13.6°, and 14.3°, corresponding to the (111), (200), (220), (311), and (222) characteristic crystal planes of UiO-66(Ce), respectively, which is in good agreement with the simulated data, indicating that UiO-66(Ce) is successfully loaded on the surface of the PEO coating.

[0080] Figure 2 Infrared spectra of the titanium alloy with a titanium oxide ceramic transition layer, the titanium alloy with nanostructures on the surface, and the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0081] From Figure 2 it can be seen that characteristic absorption peaks of O-H stretching vibrations in the range of 1623 - 1634 cm -1 and broadband in the range of 3300 - 3600 cm -1 on the PEO-Etch surface prove that the surface of the chemically etched PEO-Etch contains a large number of hydroxyl groups. The presence of these active hydroxyl functional groups ensures the adsorption of Ce 4+ cations on the coating surface, providing the necessary conditions for the in-situ growth of UiO-66(Ce). In addition, an absorption peak of P-O bending vibration appears at 1070 cm -1 due to the presence of amorphous phosphate in the coating. Absorption peaks representing the C=C vibration mode, C-O bond stretching mode, and Ce-O mode in UiO-66(Ce) are observed at 1563 cm -1 , 746 cm -1 and 1380 cm -1 for PEO / UiO-66(Ce).

[0082] Figure 3 SEM images of the titanium alloy with a titanium oxide ceramic transition layer, the titanium alloy with nanostructures on the surface, and the titanium alloy with an antibacterial nanozyme coating prepared in Example 1;

[0083] From Figure 3It can be seen that: a large number of micron / nanopores are distributed on the surface of the PEO coating, presenting a classic porous structure. After chemical etching, the PEO-Etch coating as a whole still retains the porous characteristics of the PEO coating. At high magnification, some small protrusions were observed on the surface of the PEO-Etch after chemical etching and the inner wall of the micropores, forming a complex secondary nanostructure. In fact, this unique secondary nanostructure provides an anchor point for the subsequent in-situ growth of UiO-66 (Ce) to embed nanoparticles on the coating surface. In the SEM image of PEO / UiO-66 (Ce), it can be clearly seen that the porosity of the coating surface has decreased significantly. This is because UiO-66 (Ce) has closed the smaller nanopores and defects in the PEO coating during the in-situ growth process. Under high magnification, UiO-66(Ce) was observed to grow continuously and uniformly in situ on the surface of the PEO coating and the inner wall of the micropores. These nanoparticles showed a regular polyhedral morphology and were relatively uniform in size, with a particle size of 150-200nm. They were tightly bound to the coating surface through the mechanical "interlocking" mechanism of the secondary nanostructure, forming a continuous and stable composite structure.

[0084] Figure 4 The cross-sectional SEM image and EDS surface scanning spectrum of the titanium alloy with antibacterial nanozyme coating on the surface prepared in Example 1;

[0085] from Figure 4 It can be seen that the average thickness of the antibacterial nanozyme coating on the surface prepared in Example 1 is about 15 μm; the EDS spectrum clearly shows that the cross-section of the PEO / UiO-66 (Ce) coating is mainly composed of elements such as Ti, O, Ce and Si, among which Ti comes from the TA1 substrate, Si comes from the electrolyte, and Ce comes from the UiO-66 (Ce) grown in situ on the surface.

[0086] Figure 5 This is the XPS spectrum of the titanium alloy with antibacterial nanozyme coating on the surface prepared in Example 1;

[0087] from Figure 5 a In the full spectrum, we can see that there are peaks of C1s, Ti2p, O1s and Ce3d at around 285eV, 460eV, 532eV and in the range of 870-930eV. Figure 5 The high-resolution spectrum of C1s in (b) shows three peaks at 284.79 eV, 286.36 eV, and 288.58 eV, which correspond to the C=C, CO, and C=O bonds in the PTA linker, respectively. Figure 5 c) The peaks at 465.59 eV and 459.87 eV correspond to TiO 2 Ti-O bond in O1s spectrum ( Figure 5d) The three peaks at 529.85 eV, 531.45 eV, and 532.45 eV correspond to O-C=O, Ce-OH, and Ce-O-Ce bonds, respectively. The Ce3d spectrum reveals the coexistence of Ce 3+ and Ce 4+ on the surface of UiO-66(Ce). The peaks at 885.96 eV, 899.45 eV, and 904.61 eV are related to Ce 3+ , while the peaks at 882.81 eV, 888.88 eV, 901.84 eV, 907.55 eV, and 917.32 eV are attributed to Ce 4+ .

[0088] HPO activity test:

[0089] In this invention, the bromination experiment of phenol red was used to explore the haloperoxidase activity of the PEO / UiO-66(Ce) monolithic coating. The PEO / UiO-66(Ce) sample was suspended and fixed in a beaker with stirring. 25 mL of a mixed solution containing 50 μM phenol red (PR) and 25 mM ammonium bromide (NH 4 Br) was added to the beaker to ensure that the sample was completely immersed. Subsequently, 500 μM of H 2 O 2 was injected to trigger the bromination reaction. At room temperature, 2 mL of the suspension was taken at different time intervals, and the change of the phenol red bromination reaction with time was tracked by ultraviolet-visible absorption spectroscopy in the wavelength range of 300 - 700 nm. The monitoring wavelengths of phenol red (PR) and bromophenol blue (Br 4 PR) are 432 nm and 590 nm, respectively. The experiment was continuously tracked for 480 minutes.

[0090] Figure 6 HPO activity test chart of the titanium alloy with an antibacterial nanozyme coating on the surface prepared in Example 1;

[0091] As Figure 6 shown: In the presence of H 2 O 2 and NH 4 Br, UiO-66(Ce) on the surface of PEO / UiO-66(Ce) can catalyze H 2 O 2 and Br -Hypobromous acid is generated, and the generated HOBr can react with phenol red (yellow in acidic solution) to produce bromophenol blue, turning the color of the solution into blue-violet. The results of the time-related catalytic behavior of the PEO / UiO-66(Ce) monolithic coating show that as time goes by, the absorbance peak intensity of phenol red at λ = 430 nm gradually decreases, while the absorbance peak intensity of bromophenol blue at λ = 590 nm gradually increases, visually reflecting the dynamic change process of the formation of bromophenol blue from phenol red. The results indicate that the PEO / UiO-66(Ce) monolithic coating has good HPO activity.

[0092] HPO activity cyclic stability test:

[0093] The cyclic stability of the PEO / UiO-66(Ce) monolithic coating was tested by the phenol red bromination experiment with 5 consecutive cycles of 8 hours each. During the test, the absorbance changes at wavelengths of 432 nm and 590 nm were monitored. After each 8-hour test, a new reaction solution was replaced to make the concentrations of phenol red and ammonium bromide in the reaction solution 50 μM and 25 mM respectively before the start of each cyclic test. Subsequently, 500 μM of H 2 O 2 was injected as the trigger for the start of a single reaction.

[0094] Figure 7 Figure showing the cyclic stability of the HPO activity of the titanium alloy with an antibacterial nanozyme coating on the surface prepared in Example 1. Figure 7 In the left figure, the absorbance change graph at a wavelength of 432 nm shows the cyclic degradation performance of phenol red; the right figure is the absorbance change graph at a wavelength of 590 nm, showing the cyclic formation performance graph of bromophenol blue.

[0095] Figure 7 Results of 5 consecutive 8-hour HPO activity cyclic tests of the PEO / UiO-66(Ce) coating. The results show that the enzyme-like catalytic performance slightly decreases after the first test, while it remains basically stable in subsequent tests, indicating that the PEO / UiO-66(Ce) coating has good cyclic stability.

[0096] Degradation of celestine blue:

[0097] In this invention, the degradation effect of the PEO / UiO-66(Ce) coating on the celestine blue indicator was studied, demonstrating that the coating catalyzes Br - and H 2 O 2 to produce HOBr. The PEO / UiO-66(Ce) sample was suspended and fixed in a beaker with stirring, and 25 mL of a mixed solution containing 50 μM celestine blue and 25 mM NH 4 Br was added to the beaker to ensure that the sample was completely immersed. Subsequently, 350 μM of H2 O 2 Trigger the catalytic reaction. The solution was collected every 1 hour, and the time-dependent optical absorption spectrum was recorded in the wavelength range of 400 - 800 nm, and the experiment lasted for 10 hours.

[0098] Figure 8 It is a performance graph of the degradation of celestine blue by the titanium alloy with an antibacterial nanozyme coating on the surface prepared in Example 1;

[0099] Celestine blue can only be bleached by HOBr and does not react with H 2 O 2 and superoxide radicals. In the presence of H 2 O 2 , the absorption intensity of celestine blue at 640 nm gradually decays, clearly indicating that the PEO / UiO-66(Ce) coating catalyzes the oxidation of Br - to HOBr.

[0100] Antibacterial test:

[0101] The antibacterial performance of the composite coating was characterized by the spread plate method. The antibacterial steps are as follows:

[0102] Bacterial activation: The original bacterial solution was taken out from the biomedical refrigerator at -80 °C and slowly thawed at room temperature. Then, 25 μL of the original bacterial solution was pipetted into a sterilized tube and 150 mL of LB liquid bacterial culture medium was added. The sterilized tube was placed on a shaker and cultured at 37 °C and 150 rpm for 12 h; after the bacterial culture was completed, the bacteria were washed three times with PBS solution to remove the culture medium, and the bacterial solution was diluted to a bacterial suspension with a concentration of 1.0×10 8 CFU / mL in a laminar flow hood with PBS solution.

[0103] Sample soaking: The volume of the antibacterial system was 5 mL (ensuring that the sample was completely immersed in the system), which included 125 μL of the above bacterial suspension (here, 125 μL of the 1.0×10 8 CFU / mL bacterial suspension was added to 5 mL of PBS solution to finally form a bacterial suspension with a concentration of about 10 6 , 25 mM NH 4 Br, and 500 μM H 2 O 2 . The sample was immersed in the system and cultured at 37 °C and 150 rpm for 24 h. For convenient comparison, a control group containing only bacteria, NH 4 Br, and H 2 O 2 was set up.

[0104] Quantify the antibacterial effect: Take the reaction system after culturing for 24 h above and dilute it with PBS gradient to 104 Multiply it by a factor, then take 100 μL of the diluted bacterial solution and evenly spread it on the plate medium, and culture it in an incubator at 37 °C for 24 hours. Calculate the antibacterial rate by the plate counting method.

[0105] Figure 9 It is the antibacterial performance diagram;

[0106] The test strain is Escherichia coli. From Figure 9 the results, it can be seen that PEO / UiO-66(Ce) itself shows an antibacterial rate of 43.3%, which is because UiO-66(Ce) itself has certain antibacterial activity. When 500 μM of H 2 O 2 and 25 mM of Br - are added to the system simultaneously, the antibacterial rate of PEO / UiO-66(Ce) climbs to 97.6%, indicating that the PEO / UiO-66(Ce) coating has excellent antibacterial performance catalyzed by haloperoxidase.

[0107] Comparative Example 1: Preparation method of the traditional resin-dispersed coating, which is as follows:

[0108] I. Preparation of UiO-66(Ce) nanoparticles by hydrothermal method:

[0109] Dissolve 3.506 g of (NH 4 ) 2 Ce(NO 3 ) 6 in 12 mL of deionized water, dissolve 1.062 g of terephthalic acid in 24 mL of N,N-dimethylformamide. Then mix the two solutions and stir for 30 min, transfer them to a reaction kettle, and heat at 100 °C for 3 hours. After cooling to room temperature, wash them alternately with distilled water and ethanol 3 times, and transfer them to a drying oven to dry at 60 °C for 12 hours to obtain UiO-66(Ce) nanoparticles;

[0110] II. Mix the prepared UiO-66(Ce) nanoparticles with epoxy resin (E44) at a ratio of 5 wt.%, and coat them on a titanium alloy substrate (TA1) with a coating thickness of 200 μm using a coater to obtain the traditional resin-dispersed coating.

[0111] HPO activity test:

[0112] The present invention used the phenol red bromination experiment to explore the haloperoxidase activity of the PEO / UiO-66(Ce) monolithic coating prepared in Example 1 and the coating after dispersion of the traditional resin prepared in Comparative Example 1. The PEO / UiO-66(Ce) sample and the coating after dispersion of the traditional resin prepared in Comparative Example 1 were respectively suspended and fixed in a beaker with stirring. 25 mL of a mixed solution containing 50 μM phenol red (PR) and 25 mM ammonium bromide (NH 4 Br) was added to the two beakers to ensure that the samples were completely immersed. Subsequently, 500 μM of H 2 O 2 was injected to trigger the bromination reaction. At room temperature, 2 mL of the suspension was taken out at different time intervals, and the ultraviolet-visible absorption spectrum in the wavelength range of 300 - 700 nm was used to track the change of the phenol red bromination reaction with time. The monitoring wavelengths of phenol red (PR) and bromophenol blue (Br 4 PR) were 432 nm and 590 nm respectively. The experiment was continuously tracked for 480 minutes. The UiO-66(Ce) nanozyme powder was dispersed into the resin matrix by a traditional method and coated on the substrate surface to investigate the comparison of the haloperoxidase activity between the nanozyme coating with resin as the dispersant and the in-situ grown PEO / UiO-66(Ce) coating of the present invention. The results are as Figure 10 shown;

[0113] Figure 10 is the HPO activity test chart of the titanium alloy with an antibacterial nanozyme coating on the surface prepared in Example 1 and the coating after dispersion of the traditional resin prepared in Comparative Example 1;

[0114] Figure 10 In , UiO-66(Ce) / In-situ growth is the titanium alloy with an antibacterial nanozyme coating on the surface prepared in Example 1, and UiO-66(Ce) / Resin coated is the coating after dispersion of the traditional resin prepared in Comparative Example 1;

[0115] It can be seen from Figure 10 that almost no enzyme-catalyzed reaction occurred in the nanozyme coating using resin as the dispersion medium. This is because during the dispersion of the UiO-66(Ce) nanozyme, the resin infiltrated the surface of the nanozyme, covering its surface active sites, and Br - and H 2 O 2 could not enter the active sites to trigger the reaction. In contrast, for the PEO / UiO-66(Ce) monolithic coating prepared by the in-situ growth method, since the UiO-66(Ce) nanozyme grew directly in-situ on the surface and did not need to be anchored on the substrate surface with the help of resin materials, the active sites could be fully exposed to the system, and Br - and H 2 O2 It can easily enter the active site to trigger the reaction to generate hypobromous acid. In addition, the porous structure of the PEO coating can provide more growth sites for growing more nanozymes per unit area. The synergistic effect of the excellent intrinsic peroxidase-like activity of UiO-66(Ce) nanozymes and the structural advantages of in-situ growth endows the PEO / UiO-66(Ce) monolithic coating with good haloperoxidase activity.

[0116] Test the HPO activity of the PEO titanium oxide coating according to the above method;

[0117] Figure 11 The test chart of the HPO activity of the titanium alloy with an antibacterial nanozyme coating on the surface and the PEO titanium oxide coating prepared in Example 1;

[0118] Figure 11 In it, PEO / UiO-66(Ce) is the titanium alloy with an antibacterial nanozyme coating on the surface prepared in Example 1, and PEO is the titanium oxide coating;

[0119] From Figure 11 it can be seen that under the same test conditions, no enzyme activity can be detected in the pure PEO titanium oxide coating.

Claims

1. A method for preparing an antibacterial nanozyme coating on a titanium alloy surface, characterized in that The preparation method is specifically completed according to the following steps:

1. Pretreatment of titanium alloy: The titanium alloy is polished with sandpaper, and then cleaned to remove oil stains on the surface to obtain a pretreated titanium alloy; 2. Prepare electrolyte: Na2SiO3·9H2O, Na6O 18 P6, (NaPO3) n and NaOH are dissolved in deionized water to obtain an electrolyte; 3. Connect the positive electrode of the plasma electrolytic oxidation equipment power supply to the pretreated titanium alloy, and the negative electrode to the stainless steel electrolytic tank. Pour the electrolyte into the stainless steel electrolytic tank and stir it continuously. Immerse the pretreated titanium alloy in the electrolyte at a current density of 6A / cm 2 ~10A / cm 2 , reacting for a period of time under the conditions of a duty cycle of 20% to 50% and a frequency of 500 Hz to 1000 Hz, after the reaction, taking out the titanium alloy, washing it with deionized water, and drying it to obtain a titanium alloy containing a titanium oxide ceramic transition layer; Fourth, immersing the titanium alloy containing the titanium oxide ceramic transition layer in a NaOH solution at a temperature of 60°C to 80°C for etching for a period of time, taking out the titanium alloy after the etching is completed, washing it with deionized water, and then drying it to obtain a titanium alloy with a nanostructure on the surface; five, ①, dissolve (NH4)2Ce(NO3)6 in deionized water to obtain (NH4)2Ce(NO3)6 solution; ②, dissolving terephthalic acid in N,N-dimethylformamide to obtain a terephthalic acid solution; ③. Soak the titanium alloy with nanostructures on its surface in (NH4)2Ce(NO3)6 solution for a period of time, then drop terephthalic acid solution into the (NH4)2Ce(NO3)6 solution to make terephthalic acid react with Ce on the surface of the titanium alloy. 4+ Complexation; 6. Transfer the mixed system in step 5③ to a reactor, wherein the titanium alloy is placed in the reactor at an angle of 45 degrees, and hydrothermally reacted at 100°C to 150°C for a period of time. After cooling to room temperature, the titanium alloy is taken out, and then the titanium alloy is cleaned and dried to obtain a titanium alloy with an antibacterial nanozyme coating on the surface.

2. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that In step 1, the titanium alloy is polished using 600#, 800#, 1200#, and 1500# sandpapers in sequence; the cleaning in step 1 is performed using anhydrous ethanol and acetone in sequence.

3. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that The titanium alloy described in step 1 is TA1, TA2, or TC4.

4. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that The concentration of Na2SiO3·9H2O in the electrolyte described in step 2 is 15g / L to 20g / L, and the concentration of Na6O 18 The concentration of P6 is 6g / L~10g / L, (NaPO3) n The concentration of is 2g / L~4g / L, and the concentration of NaOH is 6g / L~8g / L.

5. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that The reaction time in step three is 10 min to 20 min. After the reaction in step three is completed, the titanium alloy is taken out and washed with deionized water for 3 to 5 times to obtain a titanium alloy containing a titanium oxide ceramic transition layer.

6. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that The concentration of the NaOH solution in step 4 is 1 mol / L to 3 mol / L; the etching time in step 4 is 6 h to 24 h.

7. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that After etching in step 4 is completed, the titanium alloy is taken out, washed with deionized water for 3 to 5 times, and then dried at 60° C. to 80° C. for 6 h to 12 h to obtain a titanium alloy with a nanostructure on the surface.

8. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that The volume ratio of the mass of (NH4)2Ce(NO3)6 described in step 5① to deionized water is (3g~4g):(10mL~15mL); the volume ratio of the mass of terephthalic acid described in step 5② to N,N-dimethylformamide is (1g~1.1g):(20mL~30mL); the volume ratio of the (NH4)2Ce(NO3)6 solution described in step 5③ to terephthalic acid solution is (10mL~15mL):(20mL~30mL); the immersion time described in step 5③ is 3h~6h.

9. The method for preparing an antibacterial nanozyme coating on a titanium alloy surface according to claim 1, characterized in that The time of the hydrothermal reaction described in step six is ​​2h to 6h; in step six, deionized water, anhydrous ethanol and acetone are used to clean the titanium alloy 2 to 4 times respectively; the drying temperature described in step six is ​​60°C to 80°C, and the drying time is 6h to 12h.

10. Application of an antibacterial nanozyme coating on a titanium alloy surface prepared by the preparation method according to claim 1, characterized in that An antibacterial nanozyme coating on the surface of titanium alloy is used in the field of marine antifouling.

Images