Titanium alloy surface coating with both antibacterial and antitumor functions and application

Abstract

The present application belongs to the technical field of coating, and particularly relates to a coating with antibacterial and antitumor functions on the surface of titanium alloy and application. The coating with antibacterial and antitumor functions is complexed by Ti-PDA and ZIF-8@BA nanoparticles, Ti-PDA is obtained by immersing Ti-OH into a polydopamine solution, and ZIF-8@BA nanoparticles are obtained by loading baicalein on ZIF-8. By using the adhesion and antibacterial effect of polydopamine, a composite coating loaded with natural baicalein is constructed on the titanium surface, the coating can stabilize the loaded drug, and through the synergistic effect of Zn 2+ , baicalein and polydopamine, the coating exhibits excellent antibacterial properties, and has good biocompatibility with osteoblasts. In addition, the coating can respond to the acidic microenvironment of tumors to accelerate the release of baicalein, realize the antitumor function, and finally make the modified surface layer have antibacterial and antitumor dual functions.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically a coating and application for titanium alloy surfaces that has both antibacterial and antitumor functions. Background Technology

[0002] Titanium and its alloys are widely recognized as ideal biomedical materials in the field of orthopedics due to their good mechanical strength, low elastic modulus, excellent corrosion resistance and relatively good biocompatibility.

[0003] Pure titanium and its alloys are inherently bioinert materials. This bioinertness means that titanium implants, after being implanted into the human body, cannot actively form chemical or biological bonds with the host bone tissue, relying solely on mechanical interlocking for fixation. In the early stages of bone healing, this lack of osteoinductive activity makes it difficult to promote the rapid adhesion, proliferation, and differentiation of osteoblasts, often leading to the formation of a fibrous connective tissue capsule around the implant. This severely affects the quality of early osseointegration between the implant and surrounding bone tissue, thereby increasing the risk of implant loosening and long-term failure.

[0004] In the clinical treatment of bone tumors (such as osteosarcoma), titanium implants face even greater challenges. The standard treatment for bone tumors typically involves large-scale surgical resection of the lesion, followed by the use of titanium alloy prostheses or scaffolds to reconstruct the massive bone defect caused by tumor removal. Although surgery can remove visible tumor tissue, due to the complexity of the microscopic anatomy, trace amounts of tumor cells often inevitably remain around the surgical site. Because traditional titanium alloy surfaces lack any antitumor activity, they cannot kill or inhibit these residual tumor cells. These cells readily proliferate again in the microenvironment surrounding the implant, ultimately leading to local tumor recurrence.

[0005] Postoperative implant-related infection is another major cause of orthopedic implant failure. Implanted titanium alloy prostheses are perceived as foreign bodies by the immune system, making them highly susceptible to bacterial adhesion and colonization by bacteria (such as Staphylococcus aureus and Escherichia coli). Once bacteria adhere to the bioinert titanium surface and form a dense biofilm, they exert strong resistance to the body's immune system's phagocytic activity. More seriously, the biofilm can also block the penetration of systemically administered intravenous antibiotics, rendering traditional high-dose systemic antibiotic treatment largely ineffective. If the infection gets out of control, a second surgery to remove the implant is often necessary, along with long-term local and systemic debridement and anti-infection treatment, causing significant physical pain and a heavy financial burden for patients. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides a coating and application for titanium alloy surfaces that possess both antibacterial and antitumor functions. This invention utilizes the adhesive and antibacterial properties of polydopamine to construct a composite coating (Ti-PDA-ZIF-8@BA) loaded with natural baicalin (BA) on the titanium surface. This coating stabilizes the loaded drug while releasing Zn... 2+ The synergistic effect of BA and polydopamine exhibits excellent antibacterial properties while also demonstrating good biocompatibility with osteoblasts. Furthermore, this coating responds to the acidic tumor microenvironment, accelerating BA release and achieving antitumor function, ultimately giving the modified surface layer both antibacterial and antitumor properties.

[0007] Based on the above technical objectives, the present invention adopts the following technical solution: This invention protects a coating on the surface of a titanium alloy that has both antibacterial and antitumor functions. The coating on the surface of the titanium alloy with both antibacterial and antitumor functions is formed by complexing Ti-PDA with ZIF-8@BA nanoparticles. Ti-PDA is prepared by the following steps: Ti-OH is immersed in a polydopamine (PDA) solution, and the phenolic hydroxyl and amino groups of polydopamine are hydrogen-bonded with the hydroxyl groups of Ti-OH, so that polydopamine exists stably on the titanium surface. Then, it is vacuum dried to obtain Ti-PDA. Baicalein was loaded onto ZIF-8 to obtain ZIF-8@BA nanoparticles; A coating with both antibacterial and antitumor functions on the surface of titanium alloy was prepared according to the following steps: Ti-PDA and ZIF-8@BA nanoparticles were co-dispersed in a solvent and physically deposited. At this point, a large number of unoxidized catechol groups (phenolic hydroxyl groups) in the polydopamine structure interacted with the uncoordinated zinc ions (Zn) exposed on the ZIF-8 surface. 2+ A strong metal-ligand complexation reaction occurs, and at the same time, PDA can also play its role as a "bio-glue". Then, after centrifugation, washing and vacuum drying, a coating with both antibacterial and antitumor functions is obtained on the surface of the titanium alloy.

[0008] Preferably, the polydopamine solution is 1 mg / mL to 2 mg / mL. Too much polydopamine will cause it to detach easily, while too little will reduce its hydrophilicity and antibacterial properties.

[0009] Preferably, the mass ratio of baicalein to ZIF-8 is 0.5~1:1. Too little baicalein results in poor antibacterial and antitumor effects, while too much results in poor biocompatibility.

[0010] Preferably, the mass ratio of Ti-PDA to ZIF-8@BA nanoparticles is 1:0.00031~0.00062. Too low a concentration of ZIF-8@BA nanoparticles results in poor antibacterial and antitumor effects, while too high a concentration leads to poor biocompatibility. The mass of ZIF-8@BA nanoparticles is calculated as follows: first, weigh the Ti-PDA; after loading ZIF-8@BA, weigh the Ti-PDA-ZIF-8@BA mixture; subtract the weights to obtain the mass of ZIF-8@BA.

[0011] Preferably, the conditions for metal-ligand complexation are: standing at room temperature for 4h to 24h.

[0012] Preferably, Ti-OH is prepared by immersing a titanium alloy in an alkaline solution and subjecting it to alkaline heat treatment to obtain Ti-OH.

[0013] Preferably, the alkaline heat treatment conditions are: reacting at 60°C to 100°C for 12 to 24 hours.

[0014] Preferably, the titanium alloy is selected from Ti-Nb-Zr titanium alloy.

[0015] Preferably, the antibacterial activity is against Escherichia coli and Staphylococcus aureus, and the antitumor activity is against osteosarcoma cells.

[0016] This invention also protects the application of coatings with both antibacterial and antitumor functions on the surface of titanium alloys in the preparation of bone defect repair materials.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The coating of this invention is responsive to the acidic microenvironment of tumors. The reason for this acidic microenvironment response is that under normal physiological conditions (pH ~ 7.4), ZIF-8 maintains structural integrity with its stable Zn-N coordination bonds, effectively encapsulating the internally loaded drug and avoiding toxic side effects. However, when in the slightly acidic conditions (pH < 6.5) of the tumor microenvironment or bacterial infection area, H⁺ in the environment will rapidly induce the protonation of 2-methylimidazolium ligands, leading to the breakage of Zn-N bonds and the collapse of the MOF skeleton. It can also accelerate the targeted release of the active ingredient BA. The released natural baicalein, with its excellent anti-tumor activity, significantly inhibits the proliferation of MG-63 osteosarcoma cells and induces their apoptosis.

[0018] Zn is released from the degradation of ZIF-8 in the acidic environment of tumors. 2+Synergistically acting with BA and underlying PDA, it exhibits highly effective bactericidal activity against Escherichia coli and Staphylococcus aureus. The bactericidal mechanism is as follows: after the PDA membrane covers the surface, it forms a physical barrier, which not only hinders the initial attachment of bacteria but also cuts off the bacteria's nutrient supply network, thereby "starving" the bacteria at the source and inhibiting their growth. In addition, the benzene ring structure of dopamine and the active groups formed on the bacterial outer membrane (o-benzoquinone generated by the oxidation of catechol) produce local chemical toxicity, destroying the permeability of the bacterial cell membrane and depriving it of the essential components for maintaining life. Zn 2+ After being released from ZIF-8 and taken up by cells, Zn can disrupt cellular metabolic processes and DNA replication. 2+ They accumulate on the surface of bacteria by electrostatic adsorption, and disrupt the physical integrity of the cell membrane by replacing stable ions on the membrane, leading to leakage of intracellular substances and death.

[0019] To address the potential cytotoxicity risks associated with the release of high concentrations of metal ions, the co-loaded baicalin mitigates this issue through its antioxidant properties, maintaining the coating's excellent biocompatibility. These results confirm that the modification method combining PDA adhesion and MOF drug delivery can prepare a composite coating on titanium alloy surfaces that possesses both antibacterial and antitumor properties. This coating not only effectively avoids infection problems during surgical implantation but also significantly reduces the risk of local recurrence after osteosarcoma surgery, demonstrating significant advantages in subsequent postoperative treatment of osteosarcoma.

[0020] 2. This invention uses Ti-Nb-Zr titanium alloy as the substrate, which is a novel titanium alloy with an elastic modulus that is more compatible with human bone. The Ti-Nb-Zr titanium alloy is first subjected to NaOH alkaline heat treatment to form a nanofiber network structure on the surface. The nanofiber network structure can provide a larger specific surface area, which provides a good premise for subsequent loading of PDA and MOF. At the same time, this structure is highly biomimetic to the natural extracellular matrix of the human body. Then, it is modified by PDA and deposited into a film. Finally, ZIF-8@BA nanoparticles are successfully loaded on the PDA film. The surface of ZIF-8@BA exhibits a typical ZIF-8 rhombic dodecahedral morphology.

[0021] The introduction of PDA not only effectively improved the bioinertness of the titanium substrate (after the introduction of PDA, the water contact angle of the sample was significantly reduced, the hydrophilicity was improved, and it was easier for cells to attach and proliferate), but also provided a reliable interface for the stable assembly of ZIF-8 and BA. The binding principle of the two is mainly based on multiple non-covalent interactions at the interface: the abundant catechol and amino groups on the PDA coating surface can interact with the uncoordinated Zn on the ZIF-8 surface. 2+ In addition, 2-methylimidazole ligands generate strong coordination complexation, hydrogen bonding and π-π stacking, thereby achieving a firm anchoring of ZIF-8@BA nanoparticles. Attached Figure Description

[0022] In the figure, Ti-PDA-ZIF-8@BA are all samples from Example 1.

[0023] Figure 1 In the figure, (a) to (e) are the SEM images of Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA, respectively, and the mapping image of Ti-PDA-ZIF-8@BA.

[0024] Figure 2 In the figure, (a) shows the XRD patterns of Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA, and (b) shows the FTIR patterns of ZIF-8 powder and ZIF-8@BA powder.

[0025] Figure 3 In the figure, (a) is the total XPS spectrum of Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA; (b) is the Zn 2p spectrum of Ti-PDA-ZIF-8 and Ti-PDA-ZIF-8@BA; (c) is the C 1s spectrum of Ti-PDA-ZIF-8; and (d) is the C 1s spectrum of Ti-PDA-ZIF-8@BA.

[0026] Figure 4 The hydrophilicity diagrams are for Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA.

[0027] Figure 5 In the figure, (a) is the ultraviolet absorption spectrum of ZIF-8@BA, and the inset is the standard curve of BA; (b) is the drug release performance of Ti-PDA-ZIF-8@BA at pH=6.2 and pH=7.4; (c) is the zero-order kinetic model fitting diagram of Ti-PDA-ZIF-8@BA; (d) is the first-order kinetic model fitting diagram of Ti-PDA-ZIF-8@BA; (e) is the Higuchi model fitting diagram of Ti-PDA-ZIF-8@BA; and (f) is the Korsmeyer-Peppas model fitting diagram.

[0028] Figure 6In the figure, (a) shows the Staphylococcus aureus and Escherichia coli colony diagrams on agar plates of Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA samples; (b) shows the antibacterial rate of Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA samples against Staphylococcus aureus; and (c) shows the antibacterial rate of Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA samples against Escherichia coli.

[0029] Figure 7 In the figure, (a) shows the CCK-8 staining of osteoblasts after culturing on Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8 and Ti-PDA-ZIF-8@BA surfaces for different times, and (b) shows the live and dead staining results (Day 3) of osteoblasts after culturing on Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8 and Ti-PDA-ZIF-8@BA surfaces for different times.

[0030] Figure 8 In the figure, (a) shows the CCK-8 spectra of MG63 osteosarcoma cells after being cultured on Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA surfaces for different times, and (b) shows the live and dead staining results (Day 3) of MG63 osteosarcoma cells after being cultured on Ti, Ti-OH, Ti-PDA, Ti-PDA-ZIF-8, and Ti-PDA-ZIF-8@BA surfaces for different times.

[0031] Figure 9 This is a schematic diagram of the preparation process for the Ti-PDA-ZIF-8@BA sample. Detailed Implementation

[0032] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0033] Example 1 A method for preparing a coating on a titanium alloy surface that possesses both antibacterial and antitumor functions includes the following steps: S1. A Ti-Nb-Zr titanium alloy sheet with a shape of 10cm×10cm×3mm was polished sequentially with 400#, 800# and 2000# sandpaper, then ultrasonically cleaned with anhydrous ethanol and deionized water for 15min, and placed in a reaction vessel containing 5mol / L NaOH solution. The reaction was carried out at 80°C for 24h to obtain a Ti-OH sample.

[0034] S2. Place the Ti-OH sample into a 2 mg / mL polydopamine solution and react on a shaker for 24 h. Then remove and vacuum dry to obtain Ti-PDA.

[0035] S3. Place Ti-PDA into a reaction vessel containing 2 mg / mL ZIF-8@BA solution. The mass ratio of Ti-PDA to ZIF-8@BA nanoparticles is 1:0.00062. After reacting at 37℃ for 4 h, vacuum dry to obtain Ti-PDA-ZIF-8@BA sample, i.e., obtain PDA-ZIF-8@BA coating on titanium alloy surface.

[0036] ZIF-8@BA was prepared as follows: 1.68 g of zinc nitrate (30 mL methanol) was mixed with 4.0 g of 2-methylimidazole (70 mL methanol), stirred at room temperature for 30 min, and aged for 24 h. After centrifugation, washing with methanol, and vacuum drying, ZIF-8 powder was obtained. ZIF-8 powder and drug BA were weighed at a concentration of 2 mg / mL and dispersed together in methanol. The mixture was stirred and impregnated at room temperature in the dark for 24 h. Finally, after centrifugation, washing, and vacuum drying, ZIF-8@BA nanoparticles were obtained.

[0037] The results showed that the Ti-PDA-ZIF-8@BA sample exhibited excellent antibacterial properties, achieving an antibacterial rate of 96% against Staphylococcus aureus and 98% against Escherichia coli. Surprisingly, it also demonstrated an antitumor rate of 30% against osteosarcoma cells.

[0038] Example 2 A method for preparing a coating on a titanium alloy surface that possesses both antibacterial and antitumor functions includes the following steps: S1. A Ti-Nb-Zr titanium alloy sheet with a shape of 10cm×10cm×3mm was polished sequentially with 400#, 800# and 2000# sandpaper, then ultrasonically cleaned with anhydrous ethanol and deionized water for 15min, and placed in a reaction vessel containing 5mol / L NaOH solution. The reaction was carried out at 100°C for 12h to obtain a Ti-OH sample.

[0039] S2. Place the Ti-OH sample into a 1.5 mg / mL polydopamine solution and react on a shaker for 24 h. Then remove and vacuum dry to obtain Ti-PDA.

[0040] S3. Place Ti-PDA into a reaction vessel containing 1.5 mg / mL ZIF-8@BA solution, react at 37°C for 12 h, and then vacuum dry to obtain Ti-PDA-ZIF-8@BA sample, i.e., obtain PDA-ZIF-8@BA coating on titanium alloy surface.

[0041] Example 3 A method for preparing a coating on a titanium alloy surface that possesses both antibacterial and antitumor functions includes the following steps: S1. A Ti-Nb-Zr titanium alloy sheet with a shape of 10cm×10cm×3mm was polished sequentially with 400#, 800# and 2000# sandpaper, then ultrasonically cleaned with anhydrous ethanol and deionized water for 15min, and placed in a reaction vessel containing 5mol / L NaOH solution. The reaction was carried out at 60°C for 18h to obtain a Ti-OH sample.

[0042] S2. Place the Ti-OH sample into a 1.0 mg / mL polydopamine solution and react on a shaker for 24 h. Then remove and vacuum dry to obtain Ti-PDA.

[0043] S3. Place Ti-PDA into a reaction vessel containing 1 mg / mL ZIF-8@BA solution, react at 37°C for 24 h, and then vacuum dry to obtain Ti-PDA-ZIF-8@BA sample, i.e., obtain PDA-ZIF-8@BA coating on titanium alloy surface.

[0044] Comparative Example 1 Ti-Nb-Zr titanium alloy sheets with a shape of 10cm×10cm×3mm were successively polished with 400#, 800#, and 2000# sandpaper, and then ultrasonically cleaned with anhydrous ethanol and deionized water for 15 minutes to obtain Ti samples. The results showed that the surface of the Ti samples had no bactericidal effect against Escherichia coli and Staphylococcus aureus, nor did it have any anti-tumor effect against osteosarcoma cells.

[0045] Comparative Example 2 Ti-Nb-Zr titanium alloy sheets with a shape of 10cm×10cm×3mm were successively polished with 400#, 800#, and 2000# sandpaper, then ultrasonically cleaned with anhydrous ethanol and deionized water for 15 min. Finally, they were placed in a reaction vessel containing 5mol / L NaOH solution and reacted at 80°C for 24 h to obtain Ti-OH samples. The surface of the Ti-OH samples has a nanofiber network structure. The results showed that the surface of the Ti-OH samples had no obvious bactericidal activity against Escherichia coli and Staphylococcus aureus, with an antibacterial rate of only 5%~10%, and no tumor-killing effect on osteosarcoma cells.

[0046] Comparative Example 3 S1. A Ti-Nb-Zr titanium alloy sheet with a shape of 10cm×10cm×3mm was polished sequentially with 400#, 800# and 2000# sandpaper, then ultrasonically cleaned with anhydrous ethanol and deionized water for 15min, and placed in a reaction vessel containing 5mol / L NaOH solution. The reaction was carried out at 80°C for 24h to obtain a Ti-OH sample.

[0047] S2. Place the Ti-OH sample into a 2 mg / mL polydopamine solution and react on a shaker for 24 h. Then remove and vacuum dry to obtain Ti-PDA.

[0048] S3. Ti-PDA was placed in a reaction vessel containing 2 mg / mL ZIF-8 solution and reacted at 37°C for 4 hours. Afterward, it was vacuum dried to obtain the Ti-PDA-ZIF-8 sample. The results showed that the Ti-PDA-ZIF-8 sample exhibited an antibacterial rate of 94% against Staphylococcus aureus and 85% against Escherichia coli. However, its antitumor rate against osteosarcoma cells was only 5%.

[0049] Examples 1-3 of this invention all yielded high-performance coatings on titanium alloy surfaces with both antibacterial and antitumor functions. The following studies investigated the antibacterial effects of the five samples against *Escherichia coli* and *Staphylococcus aureus*, as well as their biocompatibility with osteoblasts and their antitumor effects against osteosarcoma cells. The specific research methods and results are shown below: (a) Evaluation of antibacterial test: I) Solid culture medium: Weigh 6.6g of nutrient agar, add it to 200mL of deionized water, sonicate until completely dissolved, and refrigerate for later use.

[0050] II) Liquid culture medium: Weigh 2.5g of NaCl and add it to 500mL of deionized water, then sonicate to disperse evenly. Separately, take 5g of tryptone and 5g of beef extract, dissolve them in a water bath, and then dilute to volume in a volumetric flask. Add all of these to the NaCl solution above. Store the prepared liquid culture medium at 4℃ for later use.

[0051] III) Bacterial culture: Gram-positive bacteria, Staphylococcus aureus, Gram-negative bacteria, and Escherichia coli were inoculated into liquid culture medium and cultured in a constant temperature incubator at 37°C for 8-12 hours.

[0052] The bacterial suspension was diluted 10,000 times and co-cultured with the samples from the examples and comparative examples for 24 hours. Then, the suspension of the sample and bacteria co-cultured was diluted 10,000 times and spread evenly on an agar plate. The culture was continued for 24 hours, and the growth of bacteria on the agar plate was observed and recorded.

[0053] (II) Osteoblast compatibility and anti-osteosarcoma activity assay: (I) Cell culture: Mouse osteoblast cell line MC3T3-E1 was cultured in α-MEM complete medium, which consisted of 10% fetal bovine serum and 90% α-MEM basal medium; human osteosarcoma cell line MG-63 was cultured in modified MEM complete medium, which consisted of 10% fetal bovine serum, 89% MEM basal medium and 1% non-essential amino acid solution.

[0054] When the cells proliferate to a density of 1×10 6 When the cell density reaches 100 cells / mL, discard the original culture medium in the culture flask and gently wash the cell monolayer twice with sterile PBS buffer. Immediately add 0.25% trypsin digestion solution and digest for 150 seconds in the culture environment. After observing under a microscope that the cells have shrunk and become rounded with increased gaps, immediately add 4 mL of the corresponding complete culture medium to stop the trypsin digestion. Transfer the cell suspension to a sterile centrifuge tube and centrifuge. After discarding the supernatant, add 1 mL of fresh complete culture medium and gently resuspend by pipetting to prepare a homogeneous single-cell suspension. Seed the suspension into two T25 disposable cell culture flasks according to the passage ratio.

[0055] All inoculated culture flasks were placed in a cell culture incubator at 37°C, 5% CO2, and saturated humidity for static culture. Cells were passaged every 2 days during culture, and subsequent experiments were conducted using cells in the third generation logarithmic growth phase.

[0056] (II) Cell viability assay: Mouse osteoblast MC3T3-E1 / osteosarcoma MG63 cells were collected and prepared into homogeneous single-cell suspensions. After adjusting the cell concentration, they were then injected at a concentration of 2×10⁻⁶ cells / cells. 4 pcs / cm 2The cells were inoculated into pre-placed cell culture plates containing the test samples at the desired inoculation density. The plates were then placed in a cell culture incubator at 37°C, 5% CO2, and saturated humidity for 1, 3, and 5 days, respectively. At each predetermined time point, the original culture medium in the wells was aspirated, and the samples and cells adhering to the sample surface were gently washed twice with sterile PBS buffer. The cell-containing test samples were then completely transferred to new sterile blank culture wells. 1 mL of a mixture of 100 μL CCK-8 reagent and 900 μL of the corresponding complete culture medium was added to each well. After gently mixing the solution, the plate was returned to the cell culture incubator and incubated in the dark for another 4 hours. After incubation, the supernatant was carefully aspirated from the wells and allowed to stand at room temperature in the dark for 15 minutes. Then, 100 μL of each sample was transferred to a 96-well microplate. The optical density (OD) of each well was measured at 450 nm using a microplate reader. Three replicates were set for each time gradient of each sample group. All experiments were independently repeated three times. The data from the three replicate experiments were used for statistical analysis (n=3).

[0057] (III) Live / dead cell staining: MC3T3-E1 cells and MG-63 cells were respectively loaded at 2×10 4 Cells were seeded at a density of cells / well onto each group of samples and cultured for 3 days. After culture, the culture medium was aspirated, and the samples were washed with PBS. Subsequently, a mixed staining solution of Calcein-AM (labeling live cells, green) and Propidium Iodide (PI, labeling dead cells, red) was added, and the samples were incubated at 37°C in the dark for 15 min. Immediately after incubation, the survival status and morphology of the two groups of cells on the sample surface were observed using a fluorescence microscope.

[0058] (IV) Statistical Analysis: Data analysis was performed using Prism (version 10.4.2) software. Experimental data are expressed as mean ± standard deviation (mean ± SD). Two-way ANOVA was used for comparisons between groups, with significance levels set at P < 0.05 (*), P < 0.01 (**), and P < 0.001 (***).

[0059] (III) Microstructure and property characterization experiments of the samples: (I) X-ray diffraction (XRD) spectroscopy test: The crystal structure of the sample was analyzed and tested using an X-ray diffractometer (XRD, RigakuSmartlab). The test speed was 5° / min and the test range was 5°~80°.

[0060] (II) Fourier transform infrared spectroscopy (FTIR) test: The chemical structure and composition were analyzed using a Fourier transform infrared spectroscopy (FTIR, Nicolet 380).

[0061] (III) Scanning electron microscopy (SEM) test: The surface morphology of the sample was observed using a scanning electron microscope (SEM, ZEISS Gemini 500).

[0062] (IV) Photoelectron spectroscopy (XPS) test: The structure of nanoparticles in each sample was elucidated and the elemental chemical states were analyzed using an X-ray photoelectron spectrometer (XPS, PHI1800).

[0063] (V) Ultraviolet-visible spectrophotometer (UV) test: Samples in different states are tested using an ultraviolet-visible spectrophotometer (UV-vis, UV-1800PC).

[0064] (VI) Hydrophilicity test: The hydrophilicity of the sample surface was assessed by the contact angle method. The water droplet volume was 2µL, and the contact angle value was recorded 5 seconds after the droplet contacted the sample surface. Three parallel samples were tested for each group to obtain the average value.

[0065] (iv) Conclusion: Figure 1 Figure (a) shows the polished titanium sheet, and SEM images show that its surface is relatively rough. Figure 1 Figure (b) shows the SEM image after NaOH alkaline heat treatment. A nanofiber network structure appears on the titanium surface. This structure can provide a larger specific surface area, which provides a good premise for subsequent PDA and MOF loading. At the same time, this structure is highly biomimetic to the human body's natural extracellular matrix. Figure 1 Figure (c) shows the result after loading PDA. As can be seen from the figure, PDA is spherical, indicating that PDA was successfully loaded onto the Ti-OH surface. Figure 1 Figure (d) shows the result after loading ZIF-8, clearly demonstrating the surface morphology of ZIF-8 and indicating successful loading. Figure 1 Figure (e) shows the ZIF-8 after being loaded with BA. It can be seen that the structure of ZIF-8 changes slightly after being loaded with BA, and BA may be loaded on both the surface and inside of ZIF-8.

[0066] from Figure 2 As can be seen in Figure (a), characteristic peaks appear after loading ZIF-8@BA, while the peaks of the titanium alloy are significantly weakened; from Figure 2 As shown in Figure (b), the FTIR results show the characteristic groups OH and C=O of baicalin, indicating that baicalin was successfully loaded.

[0067] from Figure 3As can be seen in Figure (a), ZIF-8 was successfully loaded onto the titanium sheet, and characteristic peaks of Zn ions appeared. Figure 3 Figure (b) shows the fine Zn 2p spectrum of Ti-PDA-ZIF-8 and Ti-PDA-ZIF-8@BA. Figure (d) shows the presence of C=O, which is different from Figure (c), indicating that baicalin was successfully loaded onto the titanium sheet surface.

[0068] Figure 4 The results show that the original titanium sheet has a hydrophilic angle of about 83°. After different modifications, the contact angle is significantly reduced and the hydrophilicity is improved. After loading ZIF-8, the porous structure of MOF can quickly absorb water and make it exhibit superhydrophilic characteristics.

[0069] In the analysis of drug release mechanisms in drug delivery systems, four classic kinetic models correspond to different microscopic physical processes. The zero-order kinetic model describes an ideal state where the drug is released at an absolutely constant rate, completely unaffected by the remaining drug concentration within the carrier; this is typically the ultimate goal of long-acting sustained-release systems. The first-order kinetic model reflects the most common release pattern in nature, where the release rate is proportional to the amount of drug remaining within the carrier, exhibiting a rapid burst release with a large initial concentration gradient, followed by a gradual release that diminishes as the internal drug is depleted. In contrast, the Higuchi model is specifically designed to describe drug release behavior in non-degradable porous homogeneous framework systems. It assumes that drug molecules diffuse outward through insoluble matrix pores under the simple drive of a concentration gradient, a purely physical process. To provide a more comprehensive analysis of more complex drug release environments, the Korsmeyer-Peppas model has been widely adopted. This semi-empirical model is mainly used to evaluate composite delivery systems that simultaneously involve multiple mechanisms such as molecular diffusion and the dissolution and disintegration of the scaffold itself. By calculating the release index unique to this model, researchers can accurately determine whether the drug release process is dominated by physical diffusion or by carrier disintegration, thereby profoundly revealing the underlying microscopic nature of intelligent controlled-release materials.

[0070] Figure 5 Figure (a) shows the position of the UV absorption peak of BA and the standard curve of BA (used to calculate the cumulative release rate). Figure 5 Figure (b) shows that drug release is significantly accelerated in the acidic environment of the tumor (pH=6.2). This is because ZIF-8 disintegrates (protonates) under acidic conditions, which allows for the faster release of BA. Figure 5 Figures (c) to (f) show four different kinetic models. Judging from the fitting effect, their release kinetics are more consistent with the first-order kinetic model.

[0071] Figure 6Figures (a) and (b) illustrate, from both qualitative and quantitative perspectives, that as surface treatment progresses, the number of bacteria on agar plates of various samples gradually decreases, with the Ti-PDA-ZIF-8@BA sample showing the best antibacterial effect.

[0072] Figure 7 Figures (a) and (b) in the figure together demonstrate, from both quantitative and qualitative perspectives, that the compatibility of the ZIF-8 sample loaded with baicalin is slightly reduced compared to the original Ti alloy, but the antioxidant activity of baicalin improves the cell compatibility of the titanium-based surface to some extent.

[0073] Figure 8 Figures (a) and (b) in the figure together demonstrate, from both quantitative and qualitative perspectives, that the Ti-PDA-ZIF-8@BA sample can significantly inhibit osteosarcoma cell proliferation and induce apoptosis compared to the original Ti alloy.

[0074] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A coating on a titanium alloy surface that possesses both antibacterial and antitumor functions, characterized in that, The coating on the titanium alloy surface, which has both antibacterial and antitumor functions, is composed of Ti-PDA and ZIF-8@BA nanoparticles. Ti-PDA is prepared by the following steps: Ti-OH is immersed in a polydopamine solution, and the phenolic hydroxyl and amino groups of polydopamine are hydrogen-bonded with the hydroxyl groups of Ti-OH; Baicalein was loaded onto ZIF-8 to obtain ZIF-8@BA nanoparticles; A coating with both antibacterial and antitumor functions on the surface of titanium alloy was prepared according to the following steps: Ti-PDA and ZIF-8@BA nanoparticles were co-dispersed in a solvent and physically deposited. At this time, the unoxidized phenolic hydroxyl groups in the polydopamine structure underwent metal-ligand complexation with the uncoordinated zinc ions exposed on the ZIF-8 surface.

2. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 1, characterized in that, The polydopamine solution is 1 mg / mL to 2 mg / mL.

3. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 1, characterized in that, The mass ratio of baicalein to ZIF-8 is 0.5~1:

1.

4. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 1, characterized in that, The mass ratio of Ti-PDA to ZIF-8@BA nanoparticles is 1:0.031%~0.062%.

5. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 1, characterized in that, The conditions for metal-ligand complexation are: standing at room temperature for 4 to 24 hours.

6. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 1, characterized in that, Ti-OH is prepared by immersing a titanium alloy in an alkaline solution and subjecting it to alkaline heat treatment to obtain Ti-OH.

7. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 6, characterized in that, The conditions for alkaline heat treatment are: reaction at 60°C to 100°C for 12 to 24 hours.

8. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 6, characterized in that, The titanium alloy is selected from Ti-Nb-Zr titanium alloy.

9. The coating on the titanium alloy surface with both antibacterial and antitumor functions according to claim 1, characterized in that, The antibacterial effect is against Escherichia coli and Staphylococcus aureus, and the antitumor effect is against osteosarcoma cells.

10. The application of the coating with dual antibacterial and antitumor functions on the titanium alloy surface as described in claim 1 in the preparation of bone defect repair materials.

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