Surface modified polypropylene and its preparation method and application

Abstract

The present invention discloses a surface-modified polypropylene and a preparation method thereof. The surface-modified polypropylene comprises a polypropylene substrate coated with a nano-titanium oxide / nano-zinc oxide composite coating. The nano-titanium oxide / nano-zinc oxide composite coating has a thickness of 50-200 nm and an atomic ratio of titanium to zinc of 1:0.5-5. The surface-modified polypropylene of the present invention has excellent biocompatibility and antibacterial properties. The present invention also discloses the use of the surface-modified polypropylene in the preparation of soft tissue implant materials.

Description

Technical Field

[0001] The present invention relates to the technical field of medical polypropylene, in particular to surface-modified polypropylene and a preparation method and application thereof. Background Art

[0002] The biomedical polymer material polypropylene is widely used in soft tissue implant materials due to its excellent heat resistance, corrosion resistance, good mechanical properties and light weight. It has important application value in the repair and reconstruction of abdominal wall hernias and pelvic floor defects.

[0003] However, polypropylene itself has inherent drawbacks, such as poor bioactivity, easy shrinkage, and a hydrophobic surface, which can easily trigger inflammation and rejection after implantation. Therefore, overcoming these drawbacks while maintaining the advantages of polypropylene has become a key research topic.

[0004] To address the above issues, researchers have proposed a variety of modification technologies to improve its biocompatibility, reduce inflammatory and rejection reactions, and maintain its excellent mechanical properties:

[0005] First, surface coating technology. Studies have shown that adding a titanium coating to the surface of polypropylene can significantly reduce inflammatory responses and capsular contraction. Titanium coating reduces the incidence of postoperative infection and chronic pain by improving the material's hydrophilicity and tissue compatibility. Using materials such as expanded polytetrafluoroethylene (ePTFE) as a coating can effectively reduce adhesion between the patch and surrounding tissues.

[0006] The second is the development of composite materials. Combining polypropylene with other biomaterials (such as polylactic acid and collagen) can improve its biocompatibility. For example, a composite material of polypropylene and polylactic acid has shown good anti-inflammatory and anti-adhesion properties in experiments.

[0007] Titanium-coated polypropylene is one of the most commonly used soft tissue implant materials. Compared with standard polypropylene, titanium-coated polypropylene effectively prevents severe adhesions and foreign body sensation. However, infection of titanium-coated polypropylene within the implant is a serious complication, often requiring secondary surgery to remove the implant. Summary of the Invention

[0008] The invention provides a surface-modified polypropylene having excellent biocompatibility and antibacterial properties.

[0009] The technical solutions of the present invention are as follows:

[0010] A surface-modified polypropylene comprises a polypropylene substrate, wherein the polypropylene substrate is coated with a nano-titanium oxide / nano-zinc oxide composite coating;

[0011] The thickness of the nano-titanium oxide / nano-zinc oxide composite coating is 50-200 nm; in the nano-titanium oxide / nano-zinc oxide composite coating, the atomic ratio of titanium to zinc is 1:0.5-5.

[0012] After the polypropylene substrate is modified by the nano-titanium oxide / nano-zinc oxide composite coating, its water contact angle is significantly reduced, and it has excellent hydrophilicity and biocompatibility, while the antibacterial performance is also greatly improved. Nano-ZnO can promote the cross-linking of nano-TiO2 with it, forming a three-dimensional cross-linked network structure on the polypropylene substrate. This structure enables the polypropylene substrate to quickly block and dissipate the effects of changes in the external environment, thereby reducing the aggregation of nanoparticles and improving the dispersion of nanoparticles, thereby further improving the biocompatibility and antibacterial properties of the polypropylene substrate. In the nano-titanium oxide / nano-zinc oxide composite coating, TiO2 enhances the ZnO bond between the nano-TiO2 and the polypropylene substrate. 2 + The release of Zn 2+ The sustained release of TiO2 promotes the hydroxylation of TiO2 surface and improves biocompatibility, forming a virtuous cycle of "antibacterial and healing promotion".

[0013] The surface-modified polypropylene overcomes the defects of polypropylene such as poor biological activity and easy to induce inflammation and rejection reactions.

[0014] Preferably, the thickness of the nano-titanium oxide / nano-zinc oxide composite coating is 80-100 nm.

[0015] Preferably, in the nano-titanium oxide / nano-zinc oxide composite coating, the atomic ratio of titanium to zinc is 1:3-5.

[0016] The present invention also provides a method for preparing the surface-modified polypropylene, comprising the following steps:

[0017] (1) Cleaning and surface activation of the polypropylene substrate;

[0018] (2) Atomic layer deposition was used to deposit nano-titanium oxide / nano-zinc oxide composite coating on the cleaned and surface activated polypropylene substrate.

[0019] Plasma atomic layer deposition (PEALD) can maintain the original properties of the polypropylene substrate while decomposing metal organic matter to release titanium and zinc compounds that are deposited on the surface of the polypropylene substrate, thereby achieving functional modification of the polypropylene substrate surface. This surface modification method can effectively improve the biocompatibility and antibacterial properties of polypropylene materials and has important clinical significance and application value.

[0020] Preferably, the cleaning comprises: ultrasonically cleaning the polypropylene substrate using acetone, anhydrous ethanol and ultrapure water in sequence, and drying after cleaning.

[0021] Preferably, the surface activation comprises: performing plasma surface activation on the polypropylene substrate.

[0022] Further preferably, the plasma surface activation parameters are: treatment temperature of 100-140°C, treatment time of 1-15 min, pulse time of 10000-50000 ms, purge time of 5-20 s, plasma time of 5-20 s, number of cycles: 10-50 times; argon is used as the working gas during the treatment process, and the gas pressure is maintained at 0.1-0.5 MPa.

[0023] Preferably, during the atomic layer deposition process in step (2), the titanium oxide precursor is tetrakis(dimethylamino)titanium and O2, and the zinc oxide precursor is diethylzinc and H2O.

[0024] Preferably, the atomic layer deposition process parameters in step (2) are: deposition temperature of 100-140° C., and deposition pressure of 0.1-0.5 MPa.

[0025] Preferably, during the atomic layer deposition process in step (2), the protective gas is high-purity nitrogen and the power gas is argon.

[0026] Preferably, in the atomic layer deposition process of step (2), titanium oxide is deposited 1-3 times and zinc oxide is deposited 1-3 times as one cycle, and the deposition is repeated for 200-500 cycles.

[0027] The present invention also provides application of the surface-modified polypropylene in preparing soft tissue implant materials.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] In the nano-titanium oxide / nano-zinc oxide composite coating of the surface-modified polypropylene of the present invention, nano-ZnO can promote the cross-linking of nano-TiO2 with it, forming a three-dimensional cross-linked network structure on the polypropylene substrate. This structure enables the polypropylene substrate to quickly block and dissipate the influence of external environmental changes, thereby reducing the aggregation of nanoparticles and improving the dispersibility of nanoparticles, thereby further improving the biocompatibility and antibacterial properties of the polypropylene substrate. In the nano-titanium oxide / nano-zinc oxide composite coating, TiO2 enhances the cross-linking of ZnO and the nano-TiO2, thereby improving the biocompatibility and antibacterial properties of the polypropylene substrate. 2+ The release of Zn 2+ The sustained release of TiO2 promotes the hydroxylation of TiO2 surface and improves biocompatibility, forming a virtuous cycle of "antibacterial and healing promotion". BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the full X-ray photoelectron spectrum of the TiZn-PP sample prepared in Example 1.

[0031] Figure 2These are the surface contact angles of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0032] Figure 3 These are photos of bacterial colonies on the surfaces of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0033] Figure 4 These are photos of E. coli staining on the surfaces of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0034] Figure 5 These are scanning electron microscope morphologies of Escherichia coli on the surfaces of unsurface-modified polypropylene (PP) samples, the Ti-PP samples prepared in Comparative Example 2, the Zn-PP samples prepared in Comparative Example 3, and the TiZn-PP samples prepared in Example 1.

[0035] Figure 6 for Figure 5 Partial magnification of each SEM morphology image.

[0036] Figure 7 These are photos of Staphylococcus aureus staining on the surfaces of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0037] Figure 8 These are scanning electron microscope morphologies of Staphylococcus aureus on the surfaces of unsurface-modified polypropylene (PP) samples, the Ti-PP samples prepared in Comparative Example 2, the Zn-PP samples prepared in Comparative Example 3, and the TiZn-PP samples prepared in Example 1.

[0038] Figure 9 for Figure 8 Partial magnification of each SEM morphology image.

[0039] Figure 10 These are L929 cell adhesion effect diagrams of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0040] Figure 11These are L929 cell proliferation effect diagrams of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0041] Figure 12 These are photos of L929 cell staining on the surfaces of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0042] Figure 13 These are scanning electron microscope morphologies of L929 cells on the surfaces of unsurface-modified polypropylene (PP) samples, the Ti-PP samples prepared in Comparative Example 2, the Zn-PP samples prepared in Comparative Example 3, and the TiZn-PP samples prepared in Example 1.

[0043] Figure 14 for Figure 13 Partial magnification of each SEM morphology image.

[0044] Figure 15 These are the surface roughness graphs of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1.

[0045] Figure 16 The zinc ion release amounts of the unsurface-modified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be noted that the following examples are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0047] Example 1

[0048] This embodiment provides a method for preparing surface-modified polypropylene, and the specific steps are as follows:

[0049] (1) Matrix pretreatment:

[0050] Cut medical-grade polypropylene into 10 mm x 10 mm x 1 mm specimens. Ultrasonic clean the specimens using acetone, anhydrous ethanol, and ultrapure water, sequentially for 15 minutes each time, to remove surface contaminants. After cleaning, dry the specimens in a 50°C oven until ready for use.

[0051] (2) Plasma surface activation:

[0052] The pretreated polypropylene samples were placed in a plasma treatment apparatus with the following treatment parameters: treatment temperature: 120°C, treatment time: 7 minutes, pulse time: 10,000 ms, purge time: 10.0 s, plasma time: 10.0 s, and number of cycles: 20. Argon was used as the working gas during the treatment, and the pressure was maintained at 0.1 MPa.

[0053] (3) Atomic layer deposition of titanium oxide / zinc oxide composite films:

[0054] The plasma-activated sample was transferred to an atomic layer deposition apparatus for deposition of a titanium oxide / zinc oxide composite thin film. The deposition process parameters were as follows: deposition temperature of 120°C, deposition pressure of 0.25 MPa, titanium tetrakis(dimethylamino)amino)titanium and oxygen as the titanium oxide precursor, diethylzinc and hydrogen peroxide as the zinc oxide precursor, high-purity nitrogen as the shielding gas, and argon as the motive gas. Deposition cycles consisted of three titanium oxide depositions (approximately 0.05 nm thick) and one zinc oxide deposition (approximately 0.15 nm thick) per cycle, repeated for 300 cycles. The resulting titanium oxide / zinc oxide composite thin film surface-modified polypropylene was designated TiZn-PP.

[0055] The test showed that the thickness of the titanium oxide / zinc oxide composite film on the surface of polypropylene was 90±5 nm, and the total thickness ratio of titanium oxide to zinc oxide was 1:1.

[0056] Example 2

[0057] The difference between this embodiment and embodiment 1 is that:

[0058] The number of plasma surface activation treatment cycles in step (2) was increased to 30 times, and the number of atomic layer deposition cycles in step (3) was increased to 500 times. The thickness of the titanium oxide / zinc oxide composite film was controlled at 1500±10 nm, and the total thickness ratio of titanium oxide to zinc oxide was still 1:1. Other parameters were the same as in Example 1.

[0059] The surface-modified polypropylene prepared in Example 2 had a surface contact angle of 55° and an antibacterial rate of over 98% against Staphylococcus aureus. Cytocompatibility testing showed an increased proliferation rate of L929 cells. Other properties were similar to those in Example 1.

[0060] Example 3

[0061] Compared with Example 1, the atomic layer deposition temperature in step (3) was adjusted to 100° C., and the other parameters were the same as in Example 1.

[0062] The results showed that the film deposition rate was slightly lower than that of Example 1, but the thermal deformation of the polypropylene substrate was smaller, and the other properties of the surface-modified polypropylene were similar to those of Example 1. Example 3 is particularly suitable for temperature-sensitive medical polypropylene products.

[0063] Example 4

[0064] Compared with Example 1, the atomic layer deposition temperature in step (3) was adjusted to 140° C., and the other parameters were the same as in Example 1.

[0065] The results showed that the film deposition rate was slightly improved compared with Example 1, and the other properties of the obtained surface-modified polypropylene were similar to those of Example 1.

[0066] Comparative Example 1

[0067] Compared with Example 1, the polypropylene without the plasma treatment in step (2) was directly subjected to the atomic layer deposition in step (3), and the other parameters were the same as in Example 1.

[0068] The results showed that the titanium oxide / zinc oxide composite film prepared in Comparative Example 1 had poor bonding strength with the polypropylene substrate, was easily detached, and had an unstable surface modification effect.

[0069] Comparative Example 2

[0070] Compared with Example 1, step (3) deposited only a titanium oxide film, and the number of deposition cycles was 900. Other parameters were the same as in Example 1. Polypropylene surface-modified with a titanium oxide film was obtained, denoted as Ti-PP. Testing showed that the thickness of the titanium oxide film on the polypropylene surface was 45 ± 5 nm.

[0071] Comparative Example 3

[0072] Compared with Example 1, step (3) only deposited a zinc oxide film, and the number of deposition cycles was 300. Other parameters were the same as in Example 1. The resulting zinc oxide film-surface-modified polypropylene was designated as Zn-PP. Testing showed that the thickness of the zinc oxide film on the polypropylene surface was 45 ± 5 nm.

[0073] Performance testing:

[0074] (1) If Figure 1 As shown, the chemical composition of the surface of the TiZn-PP sample prepared in Example 1 was detected by X-ray photoelectron spectroscopy. Figure 1 In (a), it can be observed that the characteristic absorption peaks of Ti element appear near the binding energy of 455.69eV, 456.76eV and 461.57eV. Figure 1In (b), characteristic absorption peaks of Zn element appear near the binding energy of 1019.37eV and 1042.58eV, where the Ti content is 2.0 at% and the Zn content is 8.1 at%. Figure 1 (a) Ti and Figure 1 The characteristic absorption peak of Zn in (b) indicates that Ti and Zn can be loaded onto the polypropylene surface after plasma and atomic layer deposition treatment.

[0075] (2) Contact angle test method: The contact angle of the sample surface was measured using a static video water contact angle meter. The specific steps are as follows: Place the sample on the glass slide on the sample stage, add 2 μL of deionized water to the sample surface via a syringe, and take a photo after the droplet on the sample surface stabilizes; use contact angle test software to analyze the contact angle value. Four samples were tested in each group. The test results were statistically analyzed.

[0076] The results of sample surface wettability test are as follows Figure 2 As shown. The contact angles of the unmodified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1 were 100.9±1.3°, 54.2±1.6°, 103.7±1.3°, and 64.2±1.5°, respectively. The surfaces of the PP and Zn-PP samples exhibited hydrophobicity, while the surfaces of the Ti-PP and TiZn-PP samples exhibited hydrophilicity. These results indicate that Ti ions can enhance the hydrophilicity of PP. Notably, the surface of the TiZn-PP sample modified with both Ti and Zn also exhibited hydrophilicity, indicating that Ti plays a decisive role in improving hydrophilicity.

[0077] (3) Antibacterial test method: Gram-positive Staphylococcus aureus (ATCC 25923) and Gram-negative Escherichia coli (ATCC 25922) were used to evaluate the antibacterial properties of the samples. Bacteria in the logarithmic growth phase were diluted to 10 7 CFU / mL. After sterilization with 75% alcohol, the sample was placed in a 24-well plate, 60 μL of bacterial solution was added to the sample surface, and the plate was cultured in a 37°C constant temperature incubator.

[0078] After 24 hours of incubation, 1 mL of normal saline was added to each well of the four groups of samples: the unsurface-modified polypropylene PP sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1. The samples were transferred to a centrifuge tube containing 4 mL of normal saline and shaken vigorously for 1 minute, and the resulting bacterial solution was diluted 10, 100, and 1000 times. 100 μL of the diluted bacterial solution was evenly spread on the surface of the agar plate, and the agar plate was inverted and placed in an incubator for incubation for 18 hours. The number of colonies on the surface of the agar plate was counted (GB / T 4789.2), and the antibacterial rate of the sample was calculated:

[0079] Antibacterial rate (%) = (AB) / A × 100%

[0080] Among them, A is the average number of colonies on the surface of Ti samples, and B is the average number of colonies on the surface of samples in the experimental group.

[0081] Escherichia coli and Staphylococcus aureus were used to evaluate the antibacterial activity of the unmodified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1. The plate colony count photos are shown in FIG. Figure 3 As shown. Compared with the control PP, the number of bacterial colonies on the agar plate surface corresponding to the Ti-PP and Zn-PP samples decreased, while the agar plate surface corresponding to the TiZn-PP sample no longer had any bacterial colonies. According to the plate colony count results, the antibacterial efficiencies of the Ti-PP, Zn-PP, and TiZn-PP samples against Escherichia coli were 10.3%, 6.5%, and 100.0%, respectively. For Staphylococcus aureus, the antibacterial efficiencies of the Ti-PP, Zn-PP, and TiZn-PP samples were 9.3%, 4.1%, and 100.0%, respectively. These results indicate that titanium-zinc synergistic modification of polypropylene can significantly improve the antibacterial efficiency of PP, and TiZn-PP exhibits excellent antibacterial properties.

[0082] Figure 4 Photographs of E. coli staining on the surfaces of unmodified polypropylene (PP), the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1. The green color in the photographs represents the fluorescence of live bacteria; stronger fluorescence indicates a higher number of live bacteria. The results show that numerous live E. coli adhere to the surfaces of the PP, Ti-PP, and Zn-PP samples. The TiZn-PP sample showed very few live E. coli and a higher number of dead bacteria, demonstrating the TiZn-PP sample's strong antibacterial activity against E. coli.

[0083] Figure 5The scanning electron microscope morphology of Escherichia coli on the surface of the unmodified polypropylene PP sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1 is shown. Figure 6 for Figure 5 The partial magnified pictures of each scanning electron microscope photograph. Figure 5 and Figure 6 As shown, the morphological changes of E. coli on the surfaces of different samples show similar trends. Numerous E. coli adhered to the PP sample, and their flagella were clearly visible, indicating healthy growth. Deformation of the E. coli was observed on the Zn-PP sample, while virtually no E. coli was visible on the TiZn-PP sample. High-magnification electron microscopy images showed severe deformation of the E. coli, with bacterial membranes lysed, indicating a state of death. Consistent with the plate-coating results, the TiZn-PP sample achieved 100% antibacterial efficacy against E. coli.

[0084] Figure 7 The following images show Staphylococcus aureus staining on unmodified polypropylene (PP), the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1. The PP sample surface is covered with abundant green fluorescence, indicating that numerous viable S. aureus bacteria adhere to the PP surface. Compared to the PP sample, the green fluorescence intensity on the Ti-PP and Zn-PP samples is reduced, indicating that the sample surfaces inhibit bacterial growth and adhesion. Green fluorescence is almost invisible on the TiZn-PP sample. Combined with the results of the plate coating, this demonstrates that the TiZn-PP sample exhibits a strong antibacterial effect against S. aureus.

[0085] Figure 8 The scanning electron microscope morphology of Staphylococcus aureus on the surface of the unmodified polypropylene PP sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1 is shown. Figure 9 for Figure 8 The partial magnified pictures of each scanning electron microscope photograph. Figure 8 and Figure 9 It can be seen that the Staphylococcus aureus on the surfaces of PP, Ti-PP, and Zn-PP samples are in good condition, showing a plump spherical morphology. The Staphylococcus aureus on the surface of the TiZn-PP sample is obviously damaged and deformed, showing excellent anti-Staphylococcus aureus effect.

[0086] (4) Cell experimental method: Mouse epithelial fibroblasts (L929, provided by the Cell Resource Center of the Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences) were seeded on the sample surface and cultured in alpha medium (α-MEM, Thermo Fisher Scientific, USA) containing 10% fetal bovine serum and 1% penicillin / streptomycin in a 37°C carbon dioxide incubator. 10 ml of α-MEM was used per plate of cells, and the medium was changed every 3 days. The third-generation cells were used for the experiment. Before the experiment, all samples were sterilized by ultraviolet irradiation overnight. The samples were blown dry in a clean bench and placed in 24-well plates for use.

[0087] The proliferation of cells on the sample surface was detected using an Alamar Blue (Thermo Fisher Scientific, USA) kit. Three unmodified polypropylene (PP) samples, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the UV-sterilized TiZn-PP sample prepared in Example 1 were placed in a 24-well plate. Each sample was seeded with 2.5 × 10 4 Cells were cultured in 1 ml of culture medium. The culture plates seeded with cells were incubated in a 37°C incubator. After 1, 3, and 7 days of culture, the culture medium was aspirated, the samples were rinsed with 1000 μl of phosphate-buffered saline (PBS), and then 500 μl of phenol red-free culture medium containing 10% FBS was added. After 4 hours of culture, 100 μl of culture medium was removed from each well and added to a 96-well plate. The absorbance (OD) of each well was measured at wavelengths of 570 nm and 600 nm using a microplate reader. Simultaneously, the cells on the sample surface were fixed with 2.5 vol% glutaraldehyde solution, dehydrated with a series of ethanol solutions (30, 50, 75, 90, and 100 vol%), and then dried with a series of ethanol and hexamethyldisilazane solutions (volume ratios of 2:1, 1:1, 1:2, and 0:1, respectively). The cell morphology on the sample surface was observed by scanning electron microscopy.

[0088] Mouse dermal fibroblasts (L929) were used to evaluate the effects of samples on cell biological behavior. Figure 10The initial adhesion and spreading of L929 cells on the surfaces of unmodified polypropylene (PP) samples, the Ti-PP samples prepared in Comparative Example 2, the Zn-PP samples prepared in Comparative Example 3, and the TiZn-PP samples prepared in Example 1 are shown. After 6 hours of culture, the L929 cells on the PP surface exhibited a spherical morphology, while the majority of cells on the Ti-PP, Zn-PP, and TiZn-PP sample surfaces showed a tendency to spread outward. After 24 hours of culture, cells on all sample surfaces exhibited a clear outward spreading morphology. Regardless of whether the cells were cultured for 6 or 24 hours, the cells on the Ti-PP, Zn-PP, and TiZn-PP sample surfaces had a larger expansion area, with the TiZn-PP sample in particular having the largest expansion area. These results demonstrate that, compared to PP, Ti-PP, Zn-PP, and TiZn-PP can enhance the initial adhesion and spreading of L929 cells, with TiZn-PP exhibiting the most significant enhancement, demonstrating the best biocompatibility.

[0089] Figure 11 The proliferation results of L929 on the surfaces of unmodified polypropylene (PP) samples, Ti-PP samples prepared in Comparative Example 2, Zn-PP samples prepared in Comparative Example 3, and TiZn-PP samples prepared in Example 1, measured by the Alamar Blue test kit, after 1, 3, and 7 days of culture. At 1 day, the cell proliferation rates on the surfaces of Ti-PP and Zn-PP samples were slightly higher than those of PP, and the cell proliferation rate on the surface of TiZn-PP samples was higher than that of the other three groups. At 3 and 7 days, the cell proliferation rates on the surfaces of Ti-PP, Zn-PP, and TiZn-PP samples were significantly higher than those of PP, among which the cell proliferation rate on the surface of TiZn-PP samples was always the highest. The above results indicate that the TiZn-PP sample can promote the proliferation of L929 cells, which is consistent with the results of cell adhesion and spreading, and exhibits excellent biocompatibility.

[0090] To further verify the biocompatibility of the samples, L929 cells cultured on the sample surface for 3 days were stained. Figure 12 As shown in the figure, compared to the unmodified polypropylene (PP) sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1 exhibited a significant amount of green fluorescence on their surfaces, with the TiZn-PP sample exhibiting the highest amount of green fluorescence. This indicates that L929 cells grew well on the Ti-PP, Zn-PP, and TiZn-PP samples, with a high number of viable cells. This confirms that the Ti-PP, Zn-PP, and TiZn-PP samples exhibited good biocompatibility and lacked cytotoxicity. Among these, the TiZn-PP sample exhibited the highest biocompatibility.

[0091] Figure 13 The scanning electron microscopy images of L929 cells after culturing on the surfaces of four groups of samples for 3 days are shown. Figure 14 for Figure 13 Magnified images of the scanning electron micrographs in Figure 2. As shown, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1 have more cells on their surfaces than the unmodified polypropylene sample. Furthermore, the magnified images show that the TiZn-PP sample exhibits the best cell spreading, consistent with the proliferation results. The TiZn-PP sample demonstrates good biocompatibility.

[0092] (5) Surface roughness

[0093] The surface roughness of the four groups of samples, namely, the unmodified polypropylene PP sample, the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1, is as follows: Figure 15 As shown in the figure, the surface roughness of the TiZn-PP sample is significantly lower. Nano-ZnO can promote the cross-linking of nano-TiO2 with it to form a three-dimensional cross-linked network structure. This structure enables the material to quickly block and dissipate the influence of changes in the external environment, thereby reducing the aggregation of nanoparticles and improving the dispersion of nanoparticles, which is more conducive to biocompatibility and antibacterial properties.

[0094] (6) Zinc ion release

[0095] The zinc ion release amounts of the Ti-PP sample prepared in Comparative Example 2, the Zn-PP sample prepared in Comparative Example 3, and the TiZn-PP sample prepared in Example 1 are as follows: Figure 16 As shown in Figure 2 , the zinc ion release rates of Ti-PP, Zn-PP, and TiZn-PP samples immersed in saline for one day were 3.966, 40.509, and 729.631 ppb, respectively. Compared to Zn-PP modified with zinc ions alone, the zinc ion release rate of TiZn-PP modified with titanium and zinc increased by 17 times. This indicates that titanium ions can promote zinc ion release, thereby improving antibacterial properties, which is consistent with the above results.

[0096] This invention combines optimized plasma treatment with atomic layer deposition technology to effectively improve the biocompatibility and antibacterial properties of polypropylene surfaces. In particular, by controlling the treatment parameters, the film's properties can be precisely controlled to meet the needs of different clinical applications.

[0097] The present invention successfully constructs a titanium-zinc synergistic functional film on the surface of polypropylene, which has the following significant characteristics:

[0098] (1) Advantages of low temperature process:

[0099] The present invention realizes the controlled release and uniform deposition of titanium and zinc active components through the precise decomposition of metal organic precursors under low temperature conditions of 100-140°C, completely avoiding the damage to the mechanical properties of the polypropylene matrix caused by high temperature treatment.

[0100] (2) Breakthrough in material performance:

[0101] This invention innovatively combines the titanium component, which has excellent biocompatibility, with the zinc component, which has outstanding antibacterial properties, to form a stable bond with the polypropylene matrix through covalent bonding, successfully developing a lightweight titanium-zinc synergistic polypropylene implant material with potential for clinical application.

[0102] (3) Verification of synergistic effect:

[0103] ①Surface characteristics:

[0104] Contact angle tests showed that the surface contact angle of the modified material was significantly reduced from 100.9±1.3° (pure PP) to 55-65°, and the surface energy was increased by about 40%, showing excellent hydrophilic properties.

[0105] ②Biological performance:

[0106] Cell experiments confirmed that the cell proliferation rate of titanium-zinc synergistically modified samples increased by more than 40% compared to pure PP. Antibacterial tests showed that the antibacterial rate against Staphylococcus aureus reached 95-98%, significantly better than that of single-component modified materials (the antibacterial rate of pure TiO2 modification was only 60%).

[0107] (4) Synergistic mechanism:

[0108] ①Structural synergy:

[0109] Nano-ZnO can promote the cross-linking of nano-TiO2 with it to form a three-dimensional cross-linked network structure. This structure enables the material to quickly block and dissipate the influence of changes in the external environment, thereby reducing the aggregation of nanoparticles and improving the dispersion of nanoparticles, which is more conducive to biocompatibility and antibacterial properties.

[0110] TiO2 lattice acts as a carrier to promote the uniform dispersion of ZnO, and ZnO nanoparticles effectively inhibit the agglomeration of TiO2 particles;

[0111] ② Functional collaboration:

[0112] Compared with PP modified with zinc ions alone, the release of zinc ions from the surface of PP modified with titanium and zinc increased by 17 times, indicating that titanium ions can promote the release of zinc ions, thereby improving antibacterial properties.

[0113] TiO2 enhanced Zn 2+ The release of Zn 2+The sustained release of TiO2 promotes the hydroxylation of TiO2 surface and improves biocompatibility, forming a virtuous cycle of "antibacterial-healing promotion";

[0114] (5) Application value:

[0115] The present invention provides an innovative solution to the problems of biological inertness and susceptibility to infection of traditional polypropylene implant materials, and opens up a new path for the development of a new generation of medical polymer materials with excellent biocompatibility and antibacterial properties. It has important application prospects in soft tissue repair fields such as abdominal wall hernia repair and pelvic floor reconstruction.

[0116] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing surface-modified polypropylene, characterized in that: The following steps are involved: (1) Cleaning the polypropylene substrate and plasma surface activation; (2) Atomic layer deposition of nano-titanium oxide / nano-zinc oxide composite coatings was performed on the cleaned and surface activated polypropylene substrate; During the atomic layer deposition process, titanium oxide is deposited 1-3 times and zinc oxide is deposited 1-3 times as one cycle, and the deposition is repeated for 200-500 cycles.

2. The method for preparing surface-modified polypropylene according to claim 1, wherein: The plasma surface activation parameters are: treatment temperature of 100-140° C., treatment time of 1-15 min, pulse time of 10,000-50,000 ms, purge time of 5-20 s, plasma time of 5-20 s, and number of cycles: 10-50 times; argon is used as the working gas during the treatment process, and the gas pressure is maintained at 0.1-0.5 MPa.

3. The method for preparing surface-modified polypropylene according to claim 1, wherein: In the atomic layer deposition process of step (2), the titanium oxide precursor is tetrakis(dimethylamino)titanium and O2, and the zinc oxide precursor is diethylzinc and H2O.

4. The method for preparing surface-modified polypropylene according to claim 1, wherein: The atomic layer deposition process parameters of step (2) are: deposition temperature of 100-140°C, and deposition pressure of 0.1-0.5 MPa.

5. A surface-modified polypropylene, characterized in that: The method is described in any one of claims 1 to 4.

6. The surface-modified polypropylene according to claim 5, characterized in that The thickness of the nano-titanium oxide / nano-zinc oxide composite coating is 50-200 nm; in the nano-titanium oxide / nano-zinc oxide composite coating, the atomic ratio of titanium to zinc is 1:0.5-5.

7. The surface-modified polypropylene according to claim 5 or 6, characterized in that: The thickness of the nano titanium oxide / nano zinc oxide composite coating is 80-100 nm.

8. The surface-modified polypropylene according to claim 5 or 6, characterized in that: In the nano-titanium oxide / nano-zinc oxide composite coating, the atomic ratio of titanium to zinc is 1:3-5.

9. Use of the surface-modified polypropylene according to any one of claims 5 to 8 in the preparation of soft tissue implant materials.

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