Method for preparing DCPD / PEI / SiO2-CuS photothermal multifunctional film on NiTi alloy surface by additive manufacturing

Abstract

This invention discloses a method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of an additively manufactured NiTi alloy, and the additively manufactured NiTi alloy prepared by this method, relating to the field of surface modification technology for medical materials. The method includes: depositing a DCPD film layer on the surface of an alloy substrate; ultrasonically mixing mesoporous SiO2 material in a mixed solution of anhydrous ethanol and deionized water, adding CuS powder for dispersion, centrifuging, washing, drying, and heat treatment to obtain a SiO2-CuS modified material; dissolving PEI in dimethylacetamide, uniformly dispersing the SiO2-CuS modified material therein to obtain an extraction solution; then immersing and pulling the NiTi alloy with the deposited DCPD film layer in the extraction solution to complete the coating of the photothermal multifunctional film layer on the NiTi alloy surface. This invention successfully improves the corrosion resistance and biocompatibility of the NiTi alloy substrate and endows its surface with highly efficient photothermal antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of medical material surface modification technology, and in particular to a method for preparing a photothermal multifunctional film layer of calcium hydrogen phosphate dihydrate / polyetherimide / silica supported copper sulfide (DCPD / PEI / SiO2-CuS) on the surface of an additively manufactured nickel-titanium (NiTi) alloy, as well as an additively manufactured NiTi alloy coated with the DCPD / PEI / SiO2-CuS photothermal multifunctional film layer. Background Technology

[0002] As the population ages, the demand for personalized medicine is becoming increasingly prominent, with ever-increasing requirements for customized implants. In recent years, laser powder bed melting technology has become a crucial technique for manufacturing high-performance medical implants, capable of directly forming complex structures and high-precision dense metal parts. Among numerous biomaterials, nickel-titanium (NiTi) alloys exhibit broad application prospects due to their unique shape memory effect, elastic modulus similar to human bone, and non-magnetic properties. However, NiTi alloys possess certain properties in physiological environments. 2+ Issues such as insufficient release, bioinertness, and antibacterial properties can all lead to the failure of the final implantation procedure. Surface modification technology has been proven to be an effective strategy for improving the functionality of metal surfaces.

[0003] DCPD (calcium hydrogen phosphate dihydrate) can be converted into hydroxyapatite (HAP) in vivo, promoting biomineralization and cell compatibility. However, its porous, scaly structure provides channels for corrosive media to penetrate the substrate, thus accelerating membrane degradation and substrate corrosion. PEI (polyetherimide), as an implantable medical polymer, possesses excellent mechanical properties, corrosion resistance, and chemical stability. However, its strong hydrophobicity and bioinertness result in poor cell adhesion and a lack of osteoinductive activity. CuS (copper sulfide), as an excellent near-infrared responsive biomaterial, can achieve localized heating under 808 nm near-infrared irradiation, utilizing its photothermal properties and slow-release Cu... 2+ While broad-spectrum antibacterial properties have led to their widespread use in the surface modification of medical materials, they suffer from drawbacks such as easy aggregation, instability, and poor biocompatibility. Mesoporous silica (SiO2), with its regular porous structure, high specific surface area, abundant surface hydroxyl groups, and good biocompatibility, can serve as an ideal carrier for CuS to inhibit its aggregation and improve its hydrophilic stability. Furthermore, the surface of mesoporous SiO2 materials is rich in active hydroxyl groups, which can effectively improve the hydrophilicity of PEI surface, slowly release bioactive silicon ions to promote osteoblast differentiation and bone regeneration, and significantly optimize the cell compatibility and bone integration performance of PEI implant materials.

[0004] Therefore, the technical problem that this invention urgently needs to solve is to structurally design and functionally combine the above materials to eliminate their respective defects and achieve synergistic effects, thereby constructing a high-performance medical implant with excellent corrosion resistance, biocompatibility and efficient antibacterial function. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of an additively manufactured NiTi alloy, and provides an additively manufactured NiTi alloy coated with the DCPD / PEI / SiO2-CuS photothermal multifunctional film layer prepared according to this method. The aim is to improve the corrosion resistance and biocompatibility of the additively manufactured NiTi alloy surface, and to utilize the photothermal effect of CuS and the slow-release of Cu... 2+ Achieve broad-spectrum and highly effective antibacterial effects.

[0006] According to one aspect of the present invention, a method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of a NiTi alloy by additive manufacturing is provided, wherein DCPD refers to calcium hydrogen phosphate dihydrate, PEI refers to polyetherimide, and SiO2-CuS refers to silicon dioxide-supported copper sulfide, comprising: S1, Matrix preparation and pretreatment: NiTi alloy matrix was prepared by additive manufacturing technology, polished and then ultrasonically treated in anhydrous ethanol and deionized water respectively, and then dried at room temperature. S2, Deposition of DCPD film: In an electrolyte solution containing calcium ions and phosphate ions, a DCPD film was deposited on the surface of the pretreated NiTi alloy substrate using a dual-electrode mode of an electrochemical workstation, with NiTi alloy as the cathode and platinum sheet as the anode. After deposition, the sample was rinsed with deionized water and dried at room temperature. S3, Preparation of mesoporous SiO2 material: Hexadecyltrimethylammonium bromide (CTAB) was added to a mixed solution of ammonium hydroxide and deionized water and stirred until clear. Then, tetraethoxysilane (TEOS) was added dropwise and stirring was continued until a white colloid was formed. The mixture was allowed to stand at room temperature, then centrifuged and washed, and calcined in a muffle furnace to obtain mesoporous SiO2 material. S4, Preparation of SiO2-CuS modified material: Mesoporous SiO2 material was added to a mixed solution of anhydrous ethanol and deionized water and sonicated. CuS powder was added and sonicated again. The mixture was stirred at room temperature, centrifuged, washed, dried and heat-treated to obtain SiO2-CuS modified material. S5, Preparation of extract: PEI is dissolved in dimethylacetamide, and then SiO2-CuS modified material is uniformly dispersed in it to obtain the extract; S6, Photothermal Multifunctional Film Preparation: NiTi alloy with deposited DCPD film is dipped and pulled in an extraction solution, followed by heat treatment.

[0007] Preferably, in S2, the distance between the anode and cathode is 2 cm, the deposition temperature is 25 °C, and the current density is 1 mA / cm². 2 The deposition time was 30 min.

[0008] Preferably, in S2, the electrolyte solution has the following specific composition: 0.1 mol / L Ca(NO3)2·4H2O, 0.06 mol / L NH4H2PO4, and 10 ml / L of an aqueous solution of 30 vol% H2O2.

[0009] Preferably, in S3, CTAB is 0.2-2 parts by mass, ammonium hydroxide solution is 3.5 parts by volume, and the total amount of TEOS added is 3-10 parts by volume.

[0010] Preferably, in step S3, stirring is carried out at 60 °C, and the mixture is washed and centrifuged with deionized water and anhydrous ethanol, respectively.

[0011] Preferably, in S3, the calcination temperature in the muffle furnace is 550 ℃, the heating rate is 1 ℃ / min, and the holding time is 4-8h.

[0012] Preferably, in S4, the volume ratio of anhydrous ethanol to deionized water is 1:1, the concentration of mesoporous SiO2 material is 1-4 g / L, and the mass ratio of mesoporous SiO2 material to CuS is 10:8.

[0013] Preferably, in S5, the PEI concentration is 10-30 wt%, and the concentration of the SiO2-CuS modified material is 1-50 mg / ml.

[0014] Preferably, in S6, the immersion and lifting speeds are both 5-15 mm / min, the immersion time is 10 min, the heat treatment temperature is 120-180 ℃, and the heat treatment time is 2-4 h.

[0015] According to another aspect of the present invention, an additive manufacturing NiTi alloy coated with a DCPD / PEI / SiO2-CuS photothermal multifunctional film is provided, which is prepared by the method described above for preparing the DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of the additive manufacturing NiTi alloy.

[0016] The beneficial effects of this invention are: (1) The present invention successfully prepared a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of additively manufactured NiTi alloy, which effectively prevented the penetration of corrosive media into the substrate, delayed the degradation of the film, enabled it to provide more durable protection to the substrate, and significantly improved the corrosion resistance of the NiTi alloy surface.

[0017] (2) The DCPD / PEI / SiO2-CuS photothermal multifunctional film prepared by this invention has excellent biocompatibility and can reduce the release of Ni from NiTi alloys due to corrosion. 2+ The cytotoxicity it induces results in higher cell activity.

[0018] (3) Photothermal effect of CuS and slow-release Cu 2+ The membrane layer achieved a broad-spectrum and highly efficient antibacterial effect, effectively inhibiting the growth and proliferation of Staphylococcus aureus and Escherichia coli. The antibacterial effect of the DCPD / PEI / SiO2-CuS membrane layer was significantly enhanced after irradiation with 808 nm near-infrared light. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic flowchart of the method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of NiTi alloy by additive manufacturing in an embodiment of the present invention; Figure 2 These are surface morphology images obtained from scanning electron microscopy (SEM), where (a), (b), (c), and (d) are SEM surface morphology images of samples 1, 2, 3, and 4, respectively. Figure 3 The figures are electrochemical analysis diagrams, where (a) is a polarization curve and (b) is a Nyquist curve. Figure 4 This is a graph showing the results of in vitro cell viability testing; Figure 5 The images show the in vitro antibacterial test results with and without near-infrared light irradiation. In the images, (a) and (b) show the antibacterial rates of Escherichia coli and Staphylococcus aureus, respectively. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of them. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present application can be combined with each other.

[0021] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0022] Unless otherwise specified, all conditions in the examples were performed under standard conditions. Reagents or instruments whose manufacturers are not specified are commercially available products. Unless otherwise stated, all technical and scientific terms herein have the meanings commonly understood by one of ordinary skill in the art.

[0023] Example 1: This example provides a method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additively manufactured NiTi alloy, referring to... Figure 1 The method includes: S1, Substrate preparation and pretreatment: NiTi alloy substrates were prepared using additive manufacturing technologies (such as laser powder bed melting, directional energy deposition, etc.). The substrates were polished with 80-800# sandpaper, and the polished NiTi alloys were ultrasonically treated in anhydrous ethanol and deionized water for 20 min respectively. After that, they were taken out and dried at room temperature to obtain the additively manufactured NiTi alloy substrate. S2, Deposition of DCPD film: A DCPD film was deposited on the surface of a pretreated additively manufactured NiTi alloy substrate using a dual-electrode mode on an electrochemical workstation. The electrolyte solution consisted of 0.1 mol / L Ca(NO3)2·4H2O, 0.06 mol / L NH4H2PO4, and 10 ml / L 30 vol% H2O2. The NiTi alloy substrate served as the cathode, and a platinum sheet served as the anode. The distance between the anode and cathode was maintained at 2 cm. The deposition was carried out at 25 °C and 1 mA / cm². 2 The sample was deposited at a current density of 30 min for 30 min. After deposition, the sample was rinsed with deionized water and dried at room temperature to obtain an additive NiTi alloy substrate with a deposited DCPD film. S3, Preparation of mesoporous SiO2 material: CTAB (0.2-2 parts by mass), ammonium hydroxide solution (3.5 parts by volume), and deionized water (480 parts by volume) were mixed and stirred at 60 °C until the solution became clear. Then, TEOS (3-10 parts by volume) was slowly added dropwise to the solution and stirring was continued until it became a white colloid. After standing at room temperature for 24 h, it was centrifuged at more than 6000 rpm for 10 min, and washed twice with deionized water and anhydrous ethanol, respectively, and then calcined in a muffle furnace at 550 °C for 4-8 h, where the heating rate of the muffle furnace was 1 °C / min, to obtain the mesoporous SiO2 material. S4, Preparation of SiO2-CuS modified material: Mesoporous SiO2 material (1-4 g / L) was added to a mixed solution of anhydrous ethanol and deionized water with a volume ratio of 1:1 and sonicated for 1 h. Then CuS powder (80% by weight of mesoporous SiO2 material) was added and sonicated for another 1 h. The mixture was stirred at room temperature for 24 h, then centrifuged at 6000 rpm for 10 min. The mixture was washed twice with deionized water and anhydrous ethanol, and then dried at 60 ℃ for 4 h under vacuum and heat-treated at 120 ℃ for 2 h to obtain SiO2-CuS modified material. S5, Preparation of extract: PEI (10-30 wt%) and SiO2-CuS modified material (1-50 mg / ml) were added to dimethylacetamide, and then stirred overnight at 300-500 rpm and ultrasonically treated for 30 min to obtain the extract; S6, Preparation of photothermal multifunctional film: The additive NiTi alloy with deposited DCPD film is immersed in the leaching solution at a uniform speed of 5-15 mm / min. After 10 min, it is pulled out at a speed of 5-15 mm / min and then heat-treated at 120-180 ℃ for 2-4 h to obtain the additive NiTi alloy coated with DCPD / PEI / SiO2-CuS photothermal multifunctional film.

[0024] This invention first utilizes mesoporous SiO2 material as a carrier for CuS material to improve its hydrophilic stability, synthesizing a SiO2-CuS modified material. Second, a DCPD / PEI / SiO2-CuS photothermal multifunctional film is prepared on the surface of an additively manufactured NiTi alloy. The prepared multifunctional film aims to synergistically enhance the corrosion resistance, cell activity, and other comprehensive properties of the NiTi alloy substrate, and to improve the overall performance through the photothermal effect of CuS material and Cu... 2+ Sustained release synergistically enhances its inhibitory effect on bacterial growth.

[0025] Furthermore, it should be noted that those skilled in the art should understand that the numerical values ​​involved in the above steps are exemplary examples of embodiments of the present invention. Although not all possible values ​​are exhaustively listed in the embodiments of the present invention, they can be flexibly adjusted according to specific circumstances in actual implementation without departing from the technical principles of the present invention. For example, the purpose of "standing for 24 hours", "centrifuging for 10 minutes", and "washing and centrifuging twice" in step S3 is to make the colloid (silicon framework structure) more stable by standing, and then to separate the precipitate by centrifugation and thoroughly wash the precipitate. In actual operation, the standing time or centrifugation time can be appropriately adjusted according to the scale of the prepared material or the actual effect, and the number of washing times can also be increased or decreased according to the washing effect. Other conventional operations are similar.

[0026] Furthermore, the following uses several comparative examples as control groups and the technical solution of the present invention as the experimental group to verify the effectiveness and progressiveness of the technical solution of the present invention.

[0027] Comparative Example 1: An additively manufactured NiTi alloy matrix, comprising: S1, Matrix preparation and pretreatment: NiTi alloy matrix was prepared by laser powder bed melting technology, and then polished with 80-800# sandpaper. The polished NiTi alloy was ultrasonically treated in anhydrous ethanol and deionized water for 20 min respectively, and then dried at room temperature to obtain additive NiTi alloy matrix, i.e., sample 1.

[0028] like Figure 2 (a) shows the SEM surface morphology of sample 1, where strip-shaped scratches formed by sandpaper polishing can be observed.

[0029] Comparative Example 2: An additive manufacturing NiTi alloy substrate for depositing a DCPD film includes: S1, Substrate preparation and pretreatment: NiTi alloy matrix was prepared by laser powder bed melting technology, and then polished with 80-800# sandpaper. The polished NiTi alloy was ultrasonically treated in anhydrous ethanol and deionized water for 20 min respectively, and then dried at room temperature to obtain additive manufacturing NiTi alloy matrix. S2, Deposition of DCPD film: A DCPD film was deposited on the surface of a pretreated additively manufactured NiTi alloy substrate using a dual-electrode mode on an electrochemical workstation. The electrolyte solution consisted of 0.1 mol / L Ca(NO3)2·4H2O, 0.06 mol / L NH4H2PO4, and 10 ml / L 30 vol% H2O2. The NiTi alloy substrate served as the cathode, and a platinum sheet served as the anode. The distance between the anode and cathode was maintained at 2 cm. The deposition was carried out at 25 °C and 1 mA / cm². 2 The sample was deposited at a current density of 30 min for 30 min. After deposition, the sample was rinsed with deionized water and dried at room temperature to obtain the additively manufactured NiTi alloy substrate with the deposited DCPD film, namely sample 2.

[0030] like Figure 2 (b) shows the SEM surface morphology of sample 2, where a typical scaly structure can be observed, indicating the successful preparation of the DCPD film.

[0031] Comparative Example 3: An additively manufactured NiTi alloy substrate coated with a DCPD / PEI film includes: S1, Substrate preparation and pretreatment: NiTi alloy matrix was prepared by laser powder bed melting technology, and then polished with 80-800# sandpaper. The polished NiTi alloy was ultrasonically treated in anhydrous ethanol and deionized water for 20 min respectively, and then dried at room temperature to obtain additive manufacturing NiTi alloy matrix. S2, Deposition of DCPD film: A DCPD film was deposited on the surface of a pretreated additively manufactured NiTi alloy substrate using a dual-electrode mode on an electrochemical workstation. The electrolyte solution consisted of 0.1 mol / L Ca(NO3)2·4H2O, 0.06 mol / L NH4H2PO4, and 10 ml / L 30 vol% H2O2. The NiTi alloy substrate served as the cathode, and a platinum sheet served as the anode. The distance between the anode and cathode was maintained at 2 cm. The deposition was carried out at 25 °C and 1 mA / cm². 2 The sample was deposited at a current density of 30 min for 30 min. After deposition, the sample was rinsed with deionized water and dried at room temperature to obtain an additive NiTi alloy substrate with a deposited DCPD film. S3, Preparation of extract: Dissolve 20 wt% PEI in dimethylacetamide and stir overnight to obtain the extract; S4, Film preparation: The additively manufactured NiTi alloy substrate with deposited DCPD film was immersed in the leaching solution at a speed of 10 mm / min. After 10 min, it was pulled out at a speed of 10 mm / min and then heat-treated at 150 °C for 2 h to obtain the additively manufactured NiTi alloy substrate coated with DCPD / PEI film, i.e., sample 3.

[0032] like Figure 2 (c) shows the SEM surface morphology of sample 3. It can be observed that compared with sample 2, its morphology has changed significantly. The scaly pores are sealed, and the surface is more uniform and dense, indicating the successful preparation of the DCPD / PEI film.

[0033] Experimental group: An additively manufactured NiTi alloy substrate coated with a DCPD / PEI / SiO2-CuS film, comprising: S1, Substrate preparation and pretreatment: NiTi alloy matrix was prepared by laser powder bed melting technology, and then polished with 80-800# sandpaper. The polished NiTi alloy was ultrasonically treated in anhydrous ethanol and deionized water for 20 min respectively, and then dried at room temperature to obtain additive manufacturing NiTi alloy matrix. S2, Deposition of DCPD film: A DCPD film was deposited on the surface of a pretreated additively manufactured NiTi alloy substrate using a dual-electrode mode on an electrochemical workstation. The electrolyte solution consisted of 0.1 mol / L Ca(NO3)2·4H2O, 0.06 mol / L NH4H2PO4, and 10 ml / L 30 vol% H2O2. The NiTi alloy substrate served as the cathode, and a platinum sheet served as the anode. The distance between the anode and cathode was maintained at 2 cm. The deposition was carried out at 25 °C and 1 mA / cm². 2 The sample was deposited at a current density of 30 min for 30 min. After deposition, the sample was rinsed with deionized water and dried at room temperature to obtain an additive NiTi alloy substrate with a deposited DCPD film. S3, Preparation of mesoporous SiO2 material: 1 g CTAB, 3.5 ml ammonium hydroxide solution and 480 ml deionized water were mixed and stirred at 60 ℃ until the solution became clear. Then, 5 ml TEOS was slowly added dropwise to the solution and stirring was continued for 2 h. The solution became a white colloid. After standing at room temperature for 24 h, it was centrifuged at more than 6000 rpm for 10 min. It was washed twice with deionized water and anhydrous ethanol, respectively, and then calcined in a muffle furnace at 550 ℃ for 6 h. The heating rate of the muffle furnace was 1 ℃ / min to obtain mesoporous SiO2 material. S4, Preparation of SiO2-CuS modified material: 0.5 g of mesoporous SiO2 material was added to a mixed solution of 100 ml anhydrous ethanol and 100 ml deionized water and sonicated for 1 h. Then, 0.4 g of CuS powder was added and sonicated for another 1 h. After stirring at room temperature for 24 h, the mixture was centrifuged at 6000 rpm for 10 min and washed twice with deionized water and anhydrous ethanol, respectively. The mixture was then dried at 60 ℃ for 4 h under vacuum and heat-treated at 120 ℃ for 2 h to obtain SiO2-CuS modified material. S5, Preparation of extract: 20 wt% PEI and 10 mg / ml SiO2-CuS modified material were added to dimethylacetamide, stirred overnight at 500 rpm and sonicated for 30 min to obtain the extract; S6, Preparation of photothermal multifunctional film: The additive manufacturing NiTi alloy substrate with deposited DCPD film is immersed in the leaching solution at a speed of 10 mm / min. After 10 min, it is pulled out at a speed of 10 mm / min and then heat-treated at 150 °C for 2 h to obtain the additive manufacturing NiTi alloy substrate coated with DCPD / PEI / SiO2-CuS film (i.e., the additive manufacturing NiTi alloy coated with DCPD / PEI / SiO2-CuS photothermal multifunctional film in this invention), namely sample 4.

[0034] like Figure 2(d) shows the SEM surface morphology of sample 4. It can be observed that the SiO2-CuS modified material is effectively encapsulated and uniformly embedded in the PEI layer, indicating that the DCPD / PEI / SiO2-CuS film layer was successfully prepared.

[0035] Reference Figure 2-5 . Figure 2 The SEM surface morphology comparison images of samples 1-4 show that the DCPD / PEI / SiO2-CuS film was successfully prepared on the surface of the additively manufactured NiTi alloy substrate.

[0036] Figure 3 This is an electrochemical analysis graph for evaluating the corrosion resistance of samples 1-4. Generally, a larger capacitance loop size in the Nyquist curve and a lower corrosion current density (Ig) in the potentiodynamic polarization curve indicate higher corrosion resistance. corr () indicates better corrosion resistance. Figure 3 (a) shows the potentiodynamic polarization curves of samples 1-4. Compared with sample 1, samples 2-4 have a lower Ig. corr . Figure 3 (b) shows the Nyquist plots for different samples. Compared to sample 1, samples 2-4 have larger capacitor circuit sizes. Sample 4 has the largest capacitor circuit size and the lowest Ic. corr This demonstrates that the DCPD / PEI / SiO2-CuS photothermal multifunctional film can significantly improve the corrosion resistance of additively manufactured NiTi alloys, achieving longer-term stable protection for the alloy substrate.

[0037] Figure 4 This image shows the in vitro cell viability assay results for samples 1-4, used to assess biocompatibility. Generally, higher cell viability indicates better biocompatibility. Figure 4 As shown, samples 2-4 all exhibited higher cell viability compared to sample 1. Specifically, the cell viability of sample 4 exceeded 100% on day 5 of culture, indicating that the DCPD / PEI / SiO2-CuS photothermal multifunctional membrane can effectively improve the biocompatibility of the membrane and is beneficial to cell proliferation and growth on the implant surface.

[0038] Figure 5 The results of in vitro antibacterial activity assays for samples 1-4 with and without 808 nm near-infrared (NIR) irradiation were presented. *Escherichia coli* and *Staphylococcus aureus* were selected as representatives of Gram-negative and Gram-positive bacteria, respectively. Sample 4 exhibited the highest antibacterial rate, and the antibacterial rate of the membrane layer significantly increased after NIR treatment, reaching over 90% against both *Escherichia coli* and *Staphylococcus aureus*. This further demonstrates that SiO2-CuS was successfully synthesized and uniformly doped into the composite membrane layer, verifying that the modified membrane layer possesses excellent photothermal response and antibacterial properties.

[0039] In summary, this invention prepares a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additively manufactured NiTi alloy. This film combines excellent corrosion resistance and good cell compatibility, providing long-term stable protection to the alloy substrate and promoting cell proliferation and growth on the implant surface. Simultaneously, CuS slowly releases Cu... 2+ Its own photothermal effect can play a synergistic antibacterial role, endowing the membrane with highly efficient antibacterial activity, effectively inhibiting the proliferation of Staphylococcus aureus and Escherichia coli on the implant surface. In particular, after 808 nm NIR treatment, the membrane can achieve an inhibition rate of more than 90% against the two pathogens, which can significantly reduce the risk of infection after implantation.

[0040] In summary, the present invention prepares a DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of additively manufactured NiTi alloy, which can effectively improve the comprehensive application performance of additively manufactured NiTi alloy implants and further broaden their application prospects in the field of medical implant materials.

[0041] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0042] The steps in the method of this invention can be adjusted, combined, or deleted according to actual needs. The technical features can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the embodiments are described. However, as long as the combinations of these technical features do not contradict each other, they should all be considered within the scope of this invention.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of additive manufacturing NiTi alloy, wherein, DCPD refers to calcium hydrogen phosphate dihydrate, PEI refers to polyetherimide, and SiO2-CuS refers to silicon dioxide-supported copper sulfide. The product is characterized by comprising: S1, Matrix preparation and pretreatment: NiTi alloy matrix was prepared by additive manufacturing technology, polished and then ultrasonically treated in anhydrous ethanol and deionized water respectively, and then dried at room temperature. S2, Deposition of DCPD film: In an electrolyte solution containing calcium ions and phosphate ions, a DCPD film was deposited on the surface of the pretreated NiTi alloy substrate using a dual-electrode mode of an electrochemical workstation, with NiTi alloy as the cathode and platinum sheet as the anode. After deposition, the sample was rinsed with deionized water and dried at room temperature. S3, Preparation of mesoporous SiO2 material: Hexadecyltrimethylammonium bromide (CTAB) was added to a mixed solution of ammonium hydroxide and deionized water and stirred until clear. Then, tetraethoxysilane (TEOS) was added dropwise and stirring was continued until a white colloid was formed. The mixture was allowed to stand at room temperature, then centrifuged and washed, and calcined in a muffle furnace to obtain mesoporous SiO2 material. S4, Preparation of SiO2-CuS modified material: Mesoporous SiO2 material was added to a mixed solution of anhydrous ethanol and deionized water and sonicated. CuS powder was added and sonicated again. The mixture was stirred at room temperature, centrifuged, washed, dried and heat-treated to obtain SiO2-CuS modified material. S5, Preparation of extract: PEI is dissolved in dimethylacetamide, and then SiO2-CuS modified material is uniformly dispersed in it to obtain the extract; S6, Photothermal Multifunctional Film Preparation: The NiTi alloy with the deposited DCPD film is immersed and pulled in an extraction solution, followed by heat treatment, to complete the preparation of DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of the additive manufacturing NiTi alloy.

2. The method for preparing DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of additive manufacturing NiTi alloy according to claim 1, characterized in that, In S2, the distance between the anode and the cathode was 2 cm, the deposition temperature was 25 °C, the current density was 1 mA / cm 2 , and the deposition time was 30 min.

3. The method for preparing DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of additive manufacturing NiTi alloy according to claim 1, characterized in that, In S2, the specific composition of the electrolyte solution is: 0.1 mol / L Ca(NO3)2·4H2O, 0.06 mol / L NH4H2PO4, and 10 ml / L of 30 vol% H2O2 aqueous solution.

4. The method of claim 1, wherein the method of additive manufacturing NiTi alloy surface preparation DCPD / PEI / SiO2-CuS photo-thermal multifunctional film layer is characterized by, In S3, CTAB is 0.2-2 parts by mass, ammonium hydroxide solution is 3.5 parts by volume, and the total amount of TEOS added is 3-10 parts by volume.

5. The method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additive manufacturing NiTi alloy according to claim 1, characterized in that, In S3, stirring was carried out at 60 °C, and the mixture was washed and centrifuged with deionized water and anhydrous ethanol, respectively.

6. The method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additive manufacturing NiTi alloy according to claim 1, characterized in that, In S3, the calcination temperature in the muffle furnace is 550 ℃, the heating rate is 1 ℃ / min, and the holding time is 4-8 h.

7. The method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additive manufacturing NiTi alloy according to claim 1, characterized in that, In S4, the volume ratio of anhydrous ethanol to deionized water is 1:1, the concentration of mesoporous SiO2 material is 1-4 g / L, and the mass ratio of mesoporous SiO2 material to CuS is 10:

8.

8. The method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additive manufacturing NiTi alloy according to claim 1, characterized in that, In S5, the PEI concentration is 10-30 wt%, and the concentration of SiO2-CuS modified material is 1-50 mg / ml.

9. The method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of an additive manufacturing NiTi alloy according to claim 1, characterized in that, In S6, the immersion and lifting speeds are both 5-15 mm / min, the immersion time is 10 min, the heat treatment temperature is 120-180 ℃, and the heat treatment time is 2-4 h.

10. An additively manufactured NiTi alloy coated with a DCPD / PEI / SiO2-CuS photothermal multifunctional film, characterized in that, The film was prepared by the additive manufacturing method for preparing DCPD / PEI / SiO2-CuS photothermal multifunctional film on the surface of NiTi alloy as described in any one of claims 1 to 9.

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