Titanium-based implant antibacterial coating, preparation method thereof and prepared titanium-based implant

Abstract

The invention relates to the technical field of antibacterial coatings, in particular to a titanium-based implant antibacterial coating, a preparation method of the titanium-based implant antibacterial coating and a prepared titanium-based implant. The coating is a Bi-TCPP compound formed by coordination bonding of bismuth ions and tetra (4-carboxyphenyl) porphyrin, and is covalently fixed on the surface of the titanium-based implant through a silane coupling agent layer. The preparation method comprises the following steps: performing cleaning and alkali heat treatment on a titanium substrate to construct an active surface; grafting a coupling agent layer through silanization reaction; the preparation method comprises the following steps: preparing a Bi-TCPP compound by a solvothermal method; and immobilizing the compound on the surface of a substrate through amidation reaction. According to the coating, efficient sterilization is achieved through pseudo-iron metabolism interference of bismuth ions and the double synergistic effect of TCPP on a bacterial membrane electron transfer chain, selective antibiosis is achieved through the structural difference between bacteria and human cells, and cytotoxicity is effectively avoided. The coating has the ultrasonic response characteristic, on-demand controlled release of antibacterial factors can be achieved, and the antibacterial efficiency and durability are remarkably improved.

Description

Technical Field

[0001] This invention relates to the technical field of antibacterial coatings, specifically to an antibacterial coating for titanium-based implants, its preparation method, and the prepared titanium-based implants. Background Technology

[0002] With the development of modern medicine, orthopedic and dental implants, such as bone screws, artificial joints, and dental implants, have been widely used in clinical practice. Titanium and its alloys have become the preferred materials for these implants due to their excellent mechanical properties and biocompatibility. However, titanium-based materials themselves do not possess inherent antibacterial capabilities. After implantation, their surfaces easily become a breeding ground for bacterial adhesion, colonization, and biofilm formation, leading to implant-related infections. These infections are a serious complication that can cause local tissue inflammation, bone resorption, and ultimately, implant loosening and failure, making treatment extremely difficult.

[0003] Currently, the main clinical approach to treating such infections still relies on systemic or local antibiotics. However, long-term use of antibiotics can easily induce bacterial resistance, giving rise to "superbugs," making traditional treatments often ineffective. In addition, bacterial biofilms on the implant surface can form a physical barrier, greatly reducing the penetration and effectiveness of antibiotics, leading to prolonged infections.

[0004] To prevent infection at its source, researchers are working to endow titanium-based implants with antibacterial properties through surface modification techniques. One approach involves constructing antibiotic-loaded coatings, which can effectively kill bacteria in the short term, but carries risks of drug burst release, short duration of action, and inducing drug resistance. Another approach utilizes inorganic antibacterial ions such as silver, zinc, and copper to prepare coatings; while these have a broad antibacterial spectrum and are less prone to inducing drug resistance, some metal ions (such as silver ions) have potential toxicity to host cells and may interfere with normal bone integration. A third approach involves immobilizing antimicrobial peptide coatings, which offer good biocompatibility, but are costly to manufacture, and their activity and long-term stability after immobilization face challenges.

[0005] Therefore, it is of great significance to develop a novel titanium-based implant surface coating that can take into account high efficiency and broad-spectrum antibacterial properties, good biocompatibility, long-term stability, and low susceptibility to inducing bacterial resistance. Summary of the Invention

[0006] The purpose of this invention is to overcome the technical problems of poor biocompatibility, easy induction of bacterial resistance, and uncontrollable drug release in existing antibacterial coatings for titanium-based implants. This invention provides an antibacterial coating for titanium-based implants, its preparation method, and the prepared titanium-based implant. A Bi-TCPP complex is constructed by combining bismuth ions with tetrakis(4-carboxyphenyl)porphyrin (TCPP), and then firmly covalently fixed to the surface of the titanium-based implant using a silanization reaction.

[0007] A first aspect of the present invention provides an antibacterial coating for a titanium-based implant, the coating comprising a Bi-TCPP complex formed by coordination bonds of bismuth and tetrakis(4-carboxyphenyl)porphyrin; the Bi-TCPP complex being covalently fixed to the surface of the titanium-based implant by a silane coupling agent layer.

[0008] This invention provides an antibacterial coating for titanium-based implants. A Bi-TCPP complex is constructed by combining bismuth ions with tetrakis(4-carboxyphenyl)porphyrin (TCPP), and then firmly covalently fixed to the surface of the titanium-based implant using a silanization reaction. Bismuth ions interfere with bacterial iron metabolism through a "pseudo-iron" mechanism, while TCPP specifically targets the bacterial outer membrane electron transport protein MtrC. The synergistic effect of these two compounds achieves a dual attack on bacterial energy and nutrient metabolism, resulting in a highly efficient and broad-spectrum antibacterial effect with low susceptibility to drug resistance. Secondly, by utilizing the fundamental differences in ultrastructure between bacteria and human cells, precise killing of bacteria is achieved, while exhibiting extremely low toxicity to normal human cells such as osteoblasts, demonstrating excellent selectivity and biocompatibility. Finally, the acoustic and thermal properties of TCPP enable the coating to respond to external ultrasonic stimulation, achieving on-demand and controllable release of antibacterial ions. This overcomes the limitation of traditional coatings that rapidly fail after "burst release," significantly extending the long-lasting antibacterial period of the implant and achieving unexpected technical effects.

[0009] Furthermore, the silane coupling agent is 3-aminopropyltriethoxysilane.

[0010] A first aspect of the present invention provides a method for preparing an antibacterial coating for a titanium-based implant as described above, comprising the following steps:

[0011] Step S1: Clean and perform alkaline heat treatment on the titanium-based implant substrate;

[0012] Step S2: Graft a silane coupling agent layer onto the substrate surface via a silanization reaction;

[0013] Step S3: Prepare the Bi-TCPP complex;

[0014] Step S4: The Bi-TCPP complex is fixed to the substrate surface through the silane coupling agent layer to form the antibacterial coating.

[0015] The preparation method of this invention constructs a hydroxyl-rich micro-network structure on the surface of a titanium substrate through cleaning and alkaline heat treatment in step S1, providing a good active interface for subsequent reactions; introduces a molecular bridging layer with active functional groups through silanization reaction in step S2, realizing a stable transition from an inorganic metal substrate to organic functional molecules; precisely constructs a Bi-TCPP complex of bismuth ions and tetrakis(4-carboxyphenyl)porphyrin through coordination bonds through a unique solvothermal process in step S3, ensuring molecular-level synergy between the two; finally, firmly anchors the functional complex to the implant surface through covalent fixation in step S4, forming an intelligent coating with high antibacterial properties, excellent biocompatibility, and ultrasonic response characteristics, effectively solving the technical problems of high biotoxicity, easy development of drug resistance, and uncontrollable drug release in traditional antibacterial coatings.

[0016] Furthermore, in step S1, the alkaline heat treatment is as follows: the cleaned titanium-based implant substrate is immersed in a 4-6 mol / L sodium hydroxide aqueous solution and heated at 70-90°C for 10-14 hours.

[0017] Furthermore, step S1 also includes: after alkaline heat treatment, sintering the titanium-based implant substrate at 500-700°C at a heating rate of 3-7°C / min.

[0018] Furthermore, the specific operation process of step 2 is as follows:

[0019] The titanium-based implant substrate was immersed in a silane coupling agent solution for silanization reaction, and the reaction time was 30 min to 2 h.

[0020] Furthermore, the volume concentration of the silane coupling agent solution is 1% to 5%.

[0021] Further, step S3 specifically includes: dissolving tetrakis(4-carboxyphenyl)porphyrin and polyvinylpyrrolidone in N,N-dimethylformamide, and sonicating to form a solution; then adding bismuth nitrate solution and acetic acid, reacting at 85-95℃ for 5-7 h, and obtaining the Bi-TCPP complex after centrifugation and washing.

[0022] Further, in step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is (10%–30%):100%. Preferably, in step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is (15%–25%):100%.

[0023] Furthermore, the specific operation process of step S4 is as follows: the substrate grafted with the silane coupling agent layer is immersed in the Bi-TCPP complex solution, so that the amino groups on its surface undergo an amidation reaction with the carboxyl groups of the Bi-TCPP complex to form an antibacterial coating.

[0024] A first aspect of the present invention provides a titanium-based implant having an antibacterial coating as described above on its surface.

[0025] The first aspect of the present invention provides a method for applying the antibacterial coating of the titanium-based implant as described above, characterized in that the implantation site with the coating is irradiated by applying ultrasonic waves to trigger and enhance its antibacterial effect.

[0026] Furthermore, the intensity of the ultrasonic wave is configured to raise the local temperature of the coating to 40°C to 50°C.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. This invention provides an antibacterial coating for titanium-based implants, which constructs a Bi-TCPP complex by combining bismuth ions with tetrakis(4-carboxyphenyl)porphyrin (TCPP) and then firmly covalently fixes it to the surface of the titanium-based implant using a silanization reaction. Bismuth ions interfere with bacterial iron metabolism through a "pseudo-iron" mechanism, while TCPP specifically targets the bacterial outer membrane electron transport protein MtrC. The synergistic effect of both achieves a dual attack on bacterial energy and nutrient metabolism, resulting in a highly efficient and broad-spectrum antibacterial effect that is less likely to induce drug resistance. Secondly, by utilizing the fundamental differences in ultrastructure between bacteria and human cells, precise killing of bacteria is achieved, while exhibiting extremely low toxicity to normal human cells such as osteoblasts, demonstrating excellent selectivity and biocompatibility. Finally, the acoustic and thermal properties of TCPP enable the coating to respond to external ultrasonic stimulation, achieving on-demand and controllable release of antibacterial ions. This overcomes the limitation of traditional coatings that rapidly fail after "burst release," significantly extending the long-term antibacterial period of the implant and achieving unexpected technical effects.

[0029] 2. The preparation method of the present invention constructs a hydroxyl-rich micro-network structure on the surface of a titanium substrate through cleaning and alkaline heat treatment in step S1, providing a good active interface for subsequent reactions; introduces a molecular bridging layer with active functional groups through silanization reaction in step S2, realizing a stable transition from an inorganic metal substrate to organic functional molecules; accurately constructs a Bi-TCPP complex of bismuth ions and tetrakis(4-carboxyphenyl)porphyrin through coordination bonds through a unique solvothermal process in step S3, ensuring molecular-level synergy between the two; finally, firmly anchors the functional complex to the implant surface through covalent fixation in step S4, forming an intelligent coating with high antibacterial properties, excellent biocompatibility, and ultrasonic response characteristics, effectively solving the technical problems of high biotoxicity, easy development of drug resistance, and uncontrollable drug release in traditional antibacterial coatings. Attached Figure Description

[0030] Figure 1 This is a scanning electron microscope (SEM) image of the titanium sheet coated with the Bi-TCPP composite of the present invention, showing its morphology and elemental distribution.

[0031] Figure 2 The images show the Fourier transform infrared spectra of the titanium sheet at various stages of the modification process.

[0032] Figure 3 A comparison chart showing the water contact angle measurement results of titanium sheet surfaces at different stages.

[0033] Figure 4 The graph shows the acoustic and thermal performance test curves of the Bi-TCPP composite coating of the present invention under ultrasonic stimulation.

[0034] Figure 5 This is a comparison of the scanning electron microscopy morphology of three bacteria under different treatment groups.

[0035] Figure 6 These are fluorescence micrographs of three bacteria treated with different methods, showing their live and dead staining effects.

[0036] Figure 7 This is a graph from a cytotoxicity assay. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0038] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0039] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0040] This embodiment provides an antibacterial coating for titanium-based implants. A Bi-TCPP complex is constructed by combining bismuth ions with tetrakis(4-carboxyphenyl)porphyrin (TCPP), and then firmly covalently fixed to the surface of the titanium-based implant using a silanization reaction. Bismuth ions interfere with bacterial iron metabolism through a "pseudo-iron" mechanism, while TCPP specifically targets the bacterial outer membrane electron transport protein MtrC. The synergistic effect of these two compounds achieves a dual attack on bacterial energy and nutrient metabolism, resulting in a highly efficient and broad-spectrum antibacterial effect with low susceptibility to drug resistance. Secondly, by utilizing the fundamental differences in ultrastructure between bacteria and human cells, precise killing of bacteria is achieved, while exhibiting extremely low toxicity to normal human cells such as osteoblasts, demonstrating excellent selectivity and biocompatibility. Finally, the acoustic and thermal properties of TCPP enable the coating to respond to external ultrasonic stimulation, achieving on-demand and controllable release of antibacterial ions. This overcomes the limitation of traditional coatings that rapidly fail after "burst release," significantly extending the long-lasting antibacterial period of the implant and achieving unexpected technical effects.

[0041] The first aspect of this embodiment provides an antibacterial coating for a titanium-based implant, the coating comprising a Bi-TCPP complex formed by coordination bonds of bismuth and tetrakis(4-carboxyphenyl)porphyrin; the Bi-TCPP complex is covalently fixed to the surface of the titanium-based implant via a silane coupling agent layer.

[0042] In some embodiments, the silane coupling agent is 3-aminopropyltriethoxysilane.

[0043] The first aspect of this embodiment provides a method for preparing the antibacterial coating of a titanium-based implant as described above, comprising the following steps:

[0044] Step S1: Clean and perform alkaline heat treatment on the titanium-based implant substrate;

[0045] Step S2: Graft a silane coupling agent layer onto the substrate surface via a silanization reaction;

[0046] Step S3: Prepare the Bi-TCPP complex;

[0047] Step S4: The Bi-TCPP complex is fixed to the substrate surface through the silane coupling agent layer to form the antibacterial coating.

[0048] The preparation method of this invention constructs a hydroxyl-rich micro-network structure on the surface of a titanium substrate through cleaning and alkaline heat treatment in step S1, providing a good active interface for subsequent reactions; introduces a molecular bridging layer with active functional groups through silanization reaction in step S2, realizing a stable transition from an inorganic metal substrate to organic functional molecules; precisely constructs a Bi-TCPP complex of bismuth ions and tetrakis(4-carboxyphenyl)porphyrin through coordination bonds through a unique solvothermal process in step S3, ensuring molecular-level synergy between the two; finally, firmly anchors the functional complex to the implant surface through covalent fixation in step S4, forming an intelligent coating with high antibacterial properties, excellent biocompatibility, and ultrasonic response characteristics, effectively solving the technical problems of high biotoxicity, easy development of drug resistance, and uncontrollable drug release in traditional antibacterial coatings.

[0049] In some embodiments, in step S1, the alkaline heat treatment involves immersing the cleaned titanium-based implant substrate in a 4–6 mol / L sodium hydroxide aqueous solution and heating it at 70–90°C for 10–14 hours. This alkaline heat treatment successfully constructs an active interface with an ideal microstructure and high-density surface hydroxyl groups on the titanium substrate surface. This not only significantly increases the specific surface area of ​​the substrate, providing ample sites for the subsequent immobilization of functional molecules, but more importantly, it greatly enhances the grafting density and binding stability of the silane coupling agent layer, thus laying a solid foundation for the robust and uniform covalent anchoring of the Bi-TCPP complex. Specifically, for example, the concentration of the sodium hydroxide aqueous solution is 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, or 6 mol / L. For example, heating at 70°C for 14 hours, at 80°C for 12 hours, and at 90°C for 10 hours.

[0050] In some embodiments, step S1 further includes: after alkaline heat treatment, sintering the titanium-based implant substrate at 500-700°C at a heating rate of 3-7°C / min. By introducing a specific high-temperature sintering process after alkaline heat treatment, the microstructure of the titanium substrate surface is stabilized and strengthened. This helps to transform the amorphous titanium hydroxide nanonetwork formed by alkaline heat treatment into anatase titanium dioxide with a more stable crystalline structure, significantly enhancing the mechanical strength and chemical stability of the surface microstructure. Simultaneously, controlling the appropriate heating rate effectively avoids coating cracking or peeling due to thermal stress, ensuring the integrity of the modified layer structure. Specifically, for example, the high-temperature sintering temperatures are 500°C, 550°C, 600°C, 650°C, and 700°C. For example, the heating rates are 3°C / min, 4°C / min, 5°C / min, 6°C / min, and 7°C / min.

[0051] In some embodiments, the specific operation process of step 2 is as follows:

[0052] The titanium-based implant substrate is immersed in a silane coupling agent solution for silanization reaction, with a reaction time of 30 min to 2 h. Specifically, for example, the reaction time is 0.5 h, 1 h, 1.5 h, or 2 h.

[0053] In some embodiments, the volume concentration of the silane coupling agent solution is 1% to 5%. By precisely controlling the volume concentration of the silane coupling agent solution within the range of 1% to 5%, a dense and stable monolayer graft can be formed on the titanium substrate surface. This concentration range ensures sufficient silane molecules to cover the active sites of the substrate while effectively avoiding multilayer physical adsorption caused by excessive concentration. The resulting uniform coupling agent layer acts as an ideal molecular bridge, significantly enhancing the binding strength between the Bi-TCPP complex and the substrate, and providing ordered fixation sites, ultimately promoting a highly uniform distribution of antibacterial functional molecules in the coating. The silane coupling agent solution is an ethanol solution of the silane coupling agent; preferably, the volume concentration of the silane coupling agent solution is 2% to 4%. Specifically, for example, the volume concentration of the silane coupling agent solution is 1%, 2%, 3%, 4%, or 5%.

[0054] In some embodiments, step S3 specifically includes: dissolving tetrakis(4-carboxyphenyl)porphyrin and polyvinylpyrrolidone in N,N-dimethylformamide, and sonicating to form a solution; then adding bismuth nitrate solution and acetic acid, reacting at 85-95°C for 5-7 h, and obtaining the Bi-TCPP complex after centrifugation and washing.

[0055] In some embodiments, in step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is (10%–30%):100%. This specific ratio helps ensure that bismuth ions can adequately coordinate with the porphyrin ring center of TCPP to form a structurally stable complex, while avoiding insufficient "iron deprivation" effect due to too low a bismuth content, or potential aggregation of TCPP molecules and impaired targeting function due to too high a bismuth content. This allows the coating to effectively interfere with bacterial iron metabolism through bismuth ions and fully utilize the dual mechanism of TCPP targeting the bacterial electron transport chain during the antibacterial process, thereby producing a significant synergistic antibacterial effect and providing a key guarantee for the coating to achieve efficient, stable, and durable antibacterial performance. Preferably, in step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is (15%–25%):100%. Specifically, for example, in step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is 10%:100%, 15%:100%, 20%:100%, 25%:100%, or 30%:100%.

[0056] In some embodiments, step S4 specifically involves immersing the substrate grafted with the silane coupling agent layer into a Bi-TCPP complex solution, causing the amino groups on its surface to undergo an amidation reaction with the carboxyl groups of the Bi-TCPP complex, thereby forming an antibacterial coating.

[0057] The first aspect of this embodiment provides a titanium-based implant with the aforementioned antibacterial coating on its surface.

[0058] The first aspect of this embodiment provides a method for applying the antibacterial coating on a titanium-based implant as described above, characterized in that an ultrasonic wave is applied to the implantation site where the coating is applied to trigger and enhance its antibacterial effect.

[0059] In some embodiments, the intensity of the ultrasonic wave is configured to raise the local temperature of the coating to 40°C to 50°C.

[0060] To better understand the technical solutions of the above embodiments, the following more detailed experimental examples are provided to explain some embodiments.

[0061] Example

[0062] Using pure titanium as a substrate, a highly effective antibacterial titanium-based implant surface coating composed of bismuth and TCPP was constructed. Bismuth, in the form of "pseudo-iron," reduces the bacterial uptake of the nutrient "iron," thereby affecting iron-sulfur cluster-related metabolism and the function of complexes I, II, and III in the electron respiratory transport chain. TCPP binds with high affinity to MtrC on the bacterial outer membrane, interfering with bacterial electron transfer and disrupting various bacterial biological processes, ultimately leading to bacterial death due to severe starvation. Combined with the acoustic and thermal properties of TCPP, the bactericidal effect is enhanced.

[0063] The specific preparation process is as follows:

[0064] (1) Cleaning of titanium sheets. Smooth titanium sheets (10 mm in diameter and 1 mm in thickness) of grade IV pure titanium are cleaned with acetone in an ultrasonic bath for 30 minutes, then cleaned with ultrapure water in an ultrasonic bath for 30 minutes, and then air-dried for later use.

[0065] (2) Alkali heat treatment of titanium sheets. The dried titanium sheets were immersed in a 5 mol / L sodium hydroxide aqueous solution, heated in an 80°C water bath for 12 hours and stirred at 120 rpm. Hydroxyl groups were formed on the surface of the titanium sheets and a micro-network structure was produced. After the treatment, the titanium sheets were removed and rinsed repeatedly with anhydrous ethanol and ultrapure water, and then allowed to dry naturally for later use.

[0066] (3) Fixation by alkaline heat treatment. Place the dried titanium sheet in a crucible and heat it to 600°C at a rate of 5°C / min in a muffle furnace. Hold it at 600°C for 1 hour and then let it cool naturally in the muffle furnace for later use.

[0067] (4) Silanization grafting modification of titanium surface. Cooled titanium sheet is immersed in an ethanol solution containing 3% 3-aminopropyltriethoxysilane (APTES) by volume for half an hour. Hydroxyl groups on the surface of titanium sheet combine with Si-OH bonds generated after hydrolysis of ATPES to form hydrogen bonds, and then dehydrate to form Si-O-Ti covalent bonds, so that aminosilane is covalently attached to the surface of titanium sheet. After removing the titanium sheet, it is gently rinsed repeatedly with anhydrous ethanol and pure water, and then air-dried for later use.

[0068] (5) Preparation of Bi-TCPP complex by solvothermal method. 40 mg TCPP and 1 g polyvinylpyrrolidone (PVP) were added to 32 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated for 2 hours. Then, bismuth nitrate solution was added dropwise at a 20% molar ratio (bismuth ion to TCPP molar ratio: 20%:100%). After stirring for 30 minutes, the reaction mixture was placed in a 90°C oven for 6 hours. Acetic acid was added to promote the entry of bismuth ions into the porphyrin ring. The mixture was centrifuged at 10,000 rpm for 20 minutes, and then the final product was washed with ethanol solution and purified water to obtain the Bi-TCPP complex.

[0069] (6) Preparation of Bi-TCPP composite coating. The dried silane coupling agent modified titanium sheet was immersed in Bi-TCPP composite solution (aqueous solution, concentration of 100 μM) and removed after 24 hours. The terminal amino groups of APTES on the surface of the titanium sheet were amidated with the carboxyl groups of the Bi-TCPP composite. The Bi-TCPP composite was covalently bonded to the surface of the titanium sheet through the silane coupling agent.

[0070] Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were performed on smooth titanium sheets and the Bi-TCPP composite-coated titanium sheets prepared in Example 1. Specifically, as shown... Figure 1 In the image, A is a scanning electron microscope image (50,000x) of a smooth titanium sheet. Figure 1 Figure B shows scanning electron microscope images of the titanium sheet coated with the Bi-TCPP composite, (i) (50,000x magnification); (ii) (100,000x magnification). Figure 1 The elemental diagram (C, N, O, Ti, Bi) of the Bi-TCPP composite coated titanium sheet is shown in Figure C.

[0071] Figure 2 Fourier transform infrared spectra of alkali-heat-treated titanium sheets, silane coupling agent ATPES solution, Bi-TCPP complex solution, and Bi-TCPP complex-coated titanium sheets confirmed the successful synthesis of the Bi-TCPP complex coating on the titanium surface.

[0072] Figure 3 Measurements of the water contact angles on the surfaces of pure smooth titanium sheets, titanium sheets modified with silane coupling agent APTES, and titanium sheets coated with Bi-TCPP composites demonstrated that the hydrophilicity of the titanium sheets was significantly enhanced after coating preparation.

[0073] Figure 4 Figure A shows the temperature change of the Bi-TCPP composite coated titanium sheet under ultrasound of different intensities. Figure B shows the temperature change of the Bi-TCPP composite coated titanium sheet under repeated switching of ultrasound, demonstrating the stability of the coating's acoustic and thermal properties.

[0074] Figure 5 Scanning electron micrographs of Staphylococcus aureus, Escherichia coli, and Porphyromonas gingivalis. The Bi-TCPP complex group showed membrane damage and shrinkage in Staphylococcus aureus, Escherichia coli, and Porphyromonas gingivalis. The Bi-TCPP complex + ultrasound group showed even more severe membrane damage and shrinkage in all bacteria, demonstrating the material's highly efficient antibacterial properties.

[0075] Figure 6 Fluorescence images of Staphylococcus aureus, Escherichia coli, and Porphyromonas gingivalis (live bacteria stained with SYTO9 stain show green fluorescence, while dead bacteria stained with PI stain show red fluorescence). In the Bi-TCPP complex group, some Staphylococcus aureus, Escherichia coli, and Porphyromonas gingivalis died; in the Bi-TCPP complex + ultrasound group, a large number of Staphylococcus aureus, Escherichia coli, and Porphyromonas gingivalis died, demonstrating the material's highly efficient antibacterial properties.

[0076] Figure 7 This is test data from a cytotoxicity experiment.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An antibacterial coating for titanium-based implants, characterized in that, The coating comprises a Bi-TCPP complex formed by coordination bonds of bismuth and tetra(4-carboxyphenyl)porphyrin; the Bi-TCPP complex is covalently fixed to the surface of the titanium-based implant through a silane coupling agent layer.

2. The antibacterial coating for titanium-based implants according to claim 1, characterized in that, The silane coupling agent is 3-aminopropyltriethoxysilane.

3. A method for preparing an antibacterial coating for a titanium-based implant as described in any one of claims 1-2, characterized in that, Includes the following steps: Step S1: Clean and perform alkaline heat treatment on the titanium-based implant substrate; Step S2: Graft a silane coupling agent layer onto the substrate surface via a silanization reaction; Step S3: Prepare the Bi-TCPP complex; Step S4: The Bi-TCPP complex is fixed to the substrate surface through the silane coupling agent layer to form the antibacterial coating.

4. The preparation method according to claim 3, characterized in that, The specific operation process of step S2 is as follows: The titanium-based implant substrate was immersed in a silane coupling agent solution for silanization reaction, and the reaction time was 30 min to 2 h.

5. The preparation method according to claim 4, characterized in that, The volume concentration of the silane coupling agent solution is 1% to 5%.

6. The preparation method according to claim 3, characterized in that, Step S3 specifically includes: dissolving tetrakis(4-carboxyphenyl)porphyrin and polyvinylpyrrolidone in N,N-dimethylformamide, and sonicating to form a solution; then adding bismuth nitrate solution and acetic acid, reacting at 85-95℃ for 5-7 h, and obtaining the Bi-TCPP complex after centrifugation and washing.

7. The preparation method according to claim 6, characterized in that, In step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is (10% to 30%): 100%.

8. The preparation method according to claim 7, characterized in that, In step S3, the molar ratio of bismuth ions to TCPP in the bismuth nitrate solution is (15% to 25%): 100%.

9. The preparation method according to claim 3, characterized in that, The specific operation process of step S4 is as follows: the substrate grafted with silane coupling agent layer is immersed in Bi-TCPP complex solution, so that the amino groups on its surface undergo amidation reaction with the carboxyl groups of Bi-TCPP complex to form an antibacterial coating.

10. A titanium-based implant, characterized in that, Its surface is provided with an antibacterial coating as described in any one of claims 1-2.

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