Preparation method and application of bionic cerium-based metal organic framework nano-enzyme for antifouling coating

Abstract

The invention discloses a preparation method and application of a bionic cerium-based metal organic framework nano-enzyme for an antifouling coating, and belongs to the technical field of antifouling coating functional materials, a metal salt solution and an amino acid solution are uniformly mixed and then subjected to a solvothermal reaction, and the bionic cerium-based metal organic framework nano-enzyme for the antifouling coating is obtained after washing and drying. The preparation method comprises the following steps: S1, preparing a metal salt solution; s2, preparing an amino acid solution; s3, preparing a complexing solution; s4, performing solvothermal reaction; and S5, washing and drying. The bionic cerium-based metal organic framework nano-enzyme for the antifouling coating prepared by the invention solves the problems of insufficient catalytic activity, poor specificity, single function and poor antifouling and anticorrosion synergistic effect, and the marine antifouling coating prepared by the nano-enzyme can effectively inhibit bacterial reproduction and microbial attachment, and has good biocompatibility. The nano-enzyme and the coating thereof have application potential in preparation of marine environment antifouling and anticorrosion and biomedical antibacterial materials.

Description

Technical Field

[0001] This invention relates to the field of antifouling coating functional materials technology, specifically to a method for preparing and applying a biomimetic cerium-based metal-organic framework nanoenzyme for antifouling coatings. Background Technology

[0002] With the continuous development of marine engineering equipment and the shipping industry, biofouling and microbial-induced corrosion (MIC) problems in the marine environment are becoming increasingly prominent. Biofouling leads to increased hull roughness, increased navigation resistance, and increased energy consumption; while MIC causes localized damage and structural degradation of metallic materials, severely shortening equipment service life and increasing maintenance costs. These two processes often reinforce each other, jointly weakening the protection system of marine facilities and posing a long-term threat to sustainable marine development.

[0003] Some enzymes in nature (such as halogenated peroxidases and oxidases) can inhibit microbial growth and biofilm formation by catalyzing the generation of reactive oxygen species (ROS), demonstrating excellent self-cleaning and protective capabilities. These biocatalytic mechanisms provide a biomimetic approach for marine protection. However, the poor stability, easy inactivation, high cost, and difficulty in large-scale production of natural enzymes limit their practical application in complex marine environments.

[0004] In contrast, nanomaterials with enzyme-like activity (i.e., nanozymes) have become promising candidate systems to replace natural enzymes due to their advantages such as high stability, strong environmental adaptability, tunable structure, and low cost. Among them, cerium-based nanozymes possess reversible Ce... 3+ / Ce 4+ Redox cycles, which can catalyze the generation of ROS under mild conditions, are widely used in antibacterial and protective applications. While existing cerium-based nanozymes and their protective materials can achieve antibacterial, antifouling, or anticorrosive effects to some extent, they still suffer from drawbacks such as insufficient catalytic activity, poor enzyme specificity, disordered structure and uncontrollable coordination, and fragmented antifouling and anticorrosive functions.

[0005] In the biomedical field, inspired by the antibacterial and antioxidant effects of natural enzymes, nanozymes have become an increasingly important research direction. However, most traditional nanozymes are amorphous or low-crystallinity particles prepared by physical or simple chemical methods. Their disordered structure leads to insufficient exposure of catalytic active sites, weak substrate binding capacity, and low catalytic conversion number and frequency. In complex physiological environments, their enzyme-like activity is easily affected by protein adsorption, pH changes, and ionic strength, resulting in catalytic efficiency far lower than that of natural enzymes or theoretical values, making it difficult to achieve effective antibacterial ROS bursts.

[0006] Therefore, there is an urgent need for a novel biomimetic cerium-based metal-organic framework nanozyme system that can mimic the metal-ligand environment of the active site of natural enzymes at the molecular level, achieving electronic structure regulation, multi-enzyme synergistic catalysis, and excellent biocompatibility. This would enable highly efficient catalysis in multiple fields, providing long-term, green, and efficient integrated protection against fouling and corrosion in complex marine environments. Furthermore, it shows great application potential in the preparation of medical materials such as antibacterial coatings and wound dressings. This is precisely the core technical problem that this invention aims to solve. Summary of the Invention

[0007] Therefore, this invention provides a method for preparing and applying a biomimetic cerium-based metal-organic framework nanoenzyme for antifouling coatings. It uses amino acids as the sole organic ligand to directly coordinate with cerium ions to construct a metal-organic framework, thereby solving the problems in the prior art caused by the use of traditional organic ligands, such as disordered catalytic active center structure, poor enzyme specificity, insufficient biocompatibility, and weak synergistic effect of antifouling and anticorrosion functions.

[0008] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings is provided. The biomimetic cerium-based metal-organic framework nanozymes are used to prepare anti-corrosion, antibacterial, and algae-inhibiting antifouling coatings or medical antibacterial materials for marine environments. The preparation method includes the following steps: S1. Preparation of metal salt solution: Soluble cerium salts are dissolved in deionized water to obtain metal salt solutions; S2. Preparation of amino acid solution: Amino acids are dissolved in a polar organic solvent to obtain an amino acid solution; S3. Preparation of complexing solution: The metal salt solution obtained in step S1 is slowly added dropwise to the amino acid solution obtained in step S2, and the dropping rate is controlled at 0.5-1 mL / min. The mixture is stirred until homogeneous to obtain a complex solution. The temperature is maintained at 20-50℃ during the stirring process. S4, Solvothermal reaction: The complex solution obtained in step S3 was transferred to a container and heated at 60℃-120℃ for a solvothermal reaction for 0.1-2 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and centrifuged to obtain the precipitate. S5. Washing and drying: The precipitate obtained in step S4 was washed, and the washed product was placed in a vacuum drying oven and dried at 40℃-80℃ for 6-24h to obtain a biomimetic cerium-based metal-organic framework nanozyme.

[0009] Further, in step S1, the soluble cerium salt is cerium ammonium nitrate, cerium nitrate, cerium sulfate, or cerium acetate. Preferred is cerium ammonium nitrate as the soluble cerium salt.

[0010] Further, in step S2, the polar organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, ethanol, N,N-dimethylacetamide, or a mixed solvent system thereof, and the amino acid contains a dicarboxyl group structure. N,N-dimethylformamide is preferably used as the polar organic solvent.

[0011] Furthermore, the amino acid containing the dicarboxyl group is glutamic acid or aspartic acid.

[0012] Further, in step S1, the concentration of the metal salt solution is 10-100 mmol / L; in step S2, the concentration of the amino acid solution is 5-100 mmol / L.

[0013] Furthermore, in step S3, the volume ratio of the metal salt solution to the amino acid solution is 1:1 to 1:5.

[0014] Further, in step S3, the dropping rate of the metal salt solution is 0.5 mL / min; in step S4, the reaction temperature of the solvothermal reaction is 80℃-110℃, the reaction time is 0.5-1h, and the heating method is one of oil bath, water bath or oven heating.

[0015] Further, in step S5, the precipitation washing method is to wash the precipitate three times each with one or more of N,N-dimethylformamide, deionized water, ethanol, and acetone, and the drying conditions are to dry at 60℃-70℃ for 10-12 hours.

[0016] According to a second aspect of the present invention, a biomimetic cerium-based metal-organic framework nanozyme for antifouling coatings prepared by the above-described preparation method is provided.

[0017] According to a third aspect of the present invention, an application of a biomimetic cerium-based metal-organic framework nanozyme for antifouling coating in the preparation of antifouling and anticorrosive materials for marine environments and medical antibacterial materials.

[0018] This invention provides an application of biomimetic cerium-based metal-organic framework nanoenzymes in antifouling and corrosion prevention in marine environments, comprising the following steps: The biomimetic cerium-based metal-organic framework nanozyme was added to the resin system at a ratio of 0.1-2.0 wt%, along with a curing agent and / or crosslinking agent, and then mixed evenly by ultrasonic dispersion and / or stirring. After coating, it cures into a film.

[0019] Preferably, the resin system is a polyacrylate, acrylic resin, polyvinylidene fluoride, epoxy resin, or polyurethane system.

[0020] Preferably, the curing agent and / or crosslinking agent is a polyamide or isocyanate.

[0021] Preferably, the coating method is spin coating, scraping coating, or spraying.

[0022] Preferably, the curing conditions are pre-curing at room temperature for 12-24 hours, followed by heat curing at 60℃-80℃ for 12-48 hours to obtain a biomimetic cerium-based metal-organic framework nanoenzyme composite coating with a thickness of 5-50μm.

[0023] The present invention has the following advantages: 1. Biomimetic Coordination Regulation Design: Unlike existing technologies that use conventional organic ligands or only modify materials with amino acids, the core innovation of this invention lies in using amino acids as the sole organic ligands, directly coordinating with cerium ions to construct a metal-organic framework, inspired by the active site of natural halogenated catalase. This design precisely simulates the amino acid coordination microenvironment of the enzyme's active site, utilizing the multidentate coordination sites provided by dicarboxylic amino acids to form a well-defined, long-range ordered all-amino acid coordination network. This unique biomimetic coordination mode achieves precise control of cerium ions. 3+ / Ce 4+ The precise regulation of redox pairs optimizes the oxygen vacancy concentration, thereby fundamentally improving the catalytic efficiency and substrate specificity of nanozymes.

[0024] 2. MOF ordered framework construction: Self-assembly of Ce ions and ligands is achieved under solvothermal or hydrothermal conditions to form a metal-organic framework structure with ordered channels. This structure significantly improves the utilization of metal atoms, enhances substrate accessibility and diffusivity, and enables catalytic reactions to proceed efficiently on high specific surface areas.

[0025] 3. Multi-enzyme synergistic protection mechanism: The obtained Ce-MOF nanozyme simultaneously possesses oxidase-like (OXD) and halogen peroxidase-like (HPO) activities, and can continuously generate ROS (such as ·O) in the marine environment. 2- (e.g., HBrO) to effectively inhibit bacteria and algae, thereby achieving a synergistic effect of antifouling and anti-corrosion.

[0026] 4. Through the comprehensive design of the above-mentioned technical means, this application has achieved electronic structure regulation and functional synergistic construction of Ce-MOF at the molecular level, which significantly improves the activity stability and environmental adaptability of the material. Attached Figure Description

[0027] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0028] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0029] Figure 1 Transmission electron microscope image of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of the present invention; Figure 2 The particle size distribution diagram of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of this invention; Figure 3 X-ray diffraction pattern of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of this invention; Figure 4 The UV-Vis absorption spectra of the halogenated peroxidase-like activity and oxidase-like activity of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of this invention; wherein Figure 4 a is the UV-Vis absorption spectrum of halogenated peroxidase activity; Figure 4 b is the UV-Vis absorption spectrum of oxidase-like activity; Figure 5 A comparison of the antibacterial properties of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of this invention against Escherichia coli and Staphylococcus aureus in different systems; Figure 6 Comparison of optical microscope and Image J images of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating and blank resin coating prepared in Example 1 of this invention for anti-algae adhesion. Figure 7 The image shows a comparison of the corrosion resistance of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating prepared in Example 1 of this invention with that of a blank copper substrate; wherein, Figure 7 Image a shows a photograph of corrosion caused by acid and alkali solutions. Figure 7 b represents the potentiodynamic polarization curve. Figure 7 c is the electrochemical impedance spectroscopy; Figure 8 Comparison of surface biofouling of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating and the blank resin coating prepared in Example 1 of the present invention after exposure to the Bohai Sea seawater environment for 0 days, 30 days and 60 days, respectively. Figure 9 The cell survival rate diagram of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of the present invention after co-culturing cells. Detailed Implementation

[0030] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] According to a first aspect of the present invention, a method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings is provided. The biomimetic cerium-based metal-organic framework nanozymes are used to prepare anti-corrosion, antibacterial, and algae-inhibiting antifouling coatings or medical antibacterial materials for marine environments. The preparation method includes the following steps: S1. Preparation of metal salt solution: Soluble cerium salts are dissolved in deionized water to obtain metal salt solutions; S2. Preparation of amino acid solution: Amino acids are dissolved in a polar organic solvent to obtain an amino acid solution; S3. Preparation of complexing solution: The metal salt solution obtained in step S1 is slowly added dropwise to the amino acid solution obtained in step S2, and the dropping rate is controlled at 0.5-1 mL / min. The mixture is stirred until homogeneous to obtain a complex solution. The temperature is maintained at 20-50℃ during the stirring process. S4, Solvothermal reaction: The complex solution obtained in step S3 was transferred to a container and heated at 60℃-120℃ for a solvothermal reaction for 0.1-2 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and centrifuged to obtain the precipitate. S5. Washing and drying: The precipitate obtained in step S4 was washed, and the washed product was placed in a vacuum drying oven and dried at 40℃-80℃ for 6-24h to obtain a biomimetic cerium-based metal-organic framework nanozyme.

[0032] In step S1, the soluble cerium salt is cerium ammonium nitrate, cerium nitrate, cerium sulfate, or cerium acetate. Preferred to be cerium ammonium nitrate is cerium ammonium nitrate.

[0033] In step S2, the polar organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, ethanol, N,N-dimethylacetamide, or a mixture thereof, and the amino acid contains a dicarboxyl group structure. Preferably, N,N-dimethylformamide is used as the polar organic solvent.

[0034] Among them, the amino acids containing a dicarboxyl group are glutamic acid or aspartic acid.

[0035] In step S1, the concentration of the metal salt solution is 10-100 mmol / L; in step S2, the concentration of the amino acid solution is 5-100 mmol / L.

[0036] In step S3, the volume ratio of the metal salt solution to the amino acid solution is 1:1 to 1:5.

[0037] In step S3, the dropping rate of the metal salt solution is 0.5 mL / min; in step S4, the reaction temperature of the solvothermal reaction is 80℃-110℃, the reaction time is 0.5-1 h, and the heating method is one of oil bath, water bath or oven heating.

[0038] In step S5, the precipitate is washed three times each with one or more of N,N-dimethylformamide, deionized water, ethanol, and acetone. The drying conditions are drying at 60℃-70℃ for 10-12 hours.

[0039] According to a second aspect of the present invention, a biomimetic cerium-based metal-organic framework nanozyme for antifouling coatings prepared by the above-described preparation method is provided.

[0040] This invention provides an application of biomimetic cerium-based metal-organic framework nanoenzymes in antifouling and corrosion prevention in marine environments, comprising the following steps: The biomimetic cerium-based metal-organic framework nanozyme was added to the resin system at a ratio of 0.1-2.0 wt%, along with a curing agent and / or crosslinking agent, and then mixed evenly by ultrasonic dispersion and / or stirring. After coating, it cures into a film.

[0041] The resin system is a polyacrylate, acrylic resin, polyvinylidene fluoride, epoxy resin, or polyurethane system.

[0042] The curing agent and / or crosslinking agent are polyamides or isocyanates.

[0043] The coating methods include spin coating, scraping coating, or spraying.

[0044] The curing conditions are as follows: pre-curing at room temperature for 12-24 hours, followed by heat curing at 60℃-80℃ for 12-48 hours to obtain a biomimetic cerium-based metal-organic framework nanoenzyme composite coating with a thickness of 5-50μm.

[0045] The innovative aspects of this invention will be described below with reference to specific embodiments.

[0046] Example 1 Preparation of biomimetic cerium-based metal-organic framework nanozymes and their application in polyacrylate composite coatings: (1) Weigh 0.5 mmol of cerium ammonium nitrate and dissolve it in 10 mL of deionized water to obtain a metal salt solution; (2) Dissolve 0.5 mmol of aspartic acid in 30 mL of N,N-dimethylformamide (DMF) and stir to form a ligand solution; (3) The metal salt solution and ligand solution were slowly added dropwise at a volume ratio of 1:3, with a dropping rate of 0.5 mL / min, and the temperature was maintained at 25℃ while stirring for 10 min. (4) The mixed solution was placed in a pressure-resistant tube and reacted in a water bath at 100°C for 0.5 h. After cooling, it was centrifuged and washed three times each with DMF, deionized water and ethanol. (5) Drying conditions: Vacuum drying at 60℃ for 10h to obtain biomimetic cerium-based metal-organic framework nanoenzyme light yellow powder (Ce-MOF); (6) The obtained powder was added to the polyacrylate system at 0.6 wt%, and then 10% hexamethylene diisocyanate by mass of polyacrylate was added. The mixture was ultrasonically dispersed for 15 min and magnetically stirred for 30 min. After vacuum degassing, the mixture was coated onto the surface of the epoxy resin matrix. After pre-curing at room temperature for 12 h, it was heat-cured at 70 °C for 24 h to form an anti-fouling and anti-corrosion coating with a thickness of about 35 μm.

[0047] Example 2 Preparation of biomimetic cerium-based metal-organic framework nanozymes and their application in acrylic resin protection systems: (1) Weigh 0.5 mmol of cerium ammonium nitrate and dissolve it in 10 mL of deionized water to obtain a metal salt solution; (2) Dissolve 0.3 mmol of glutamic acid in 30 mL of DMF and stir to form a ligand solution; (3) Add the metal salt solution to the ligand solution at a rate of 1 mL / min, with a volume ratio of 1:3 between the metal salt solution and the ligand solution, and maintain the temperature at 25℃ while stirring for 20 min; (4) The mixed solution was reacted in an oil bath at 110℃ for 0.5h; (5) After washing three times with DMF and ethanol, the mixture was vacuum dried at 60°C for 12 hours to obtain a light yellow powder of biomimetic cerium-based metal-organic framework nanoenzymes. (6) The obtained powder was added to the acrylic resin system at 1.2 wt%, and 10% hexamethylene diisocyanate was added by weight of the acrylic resin. The mixture was ultrasonically dispersed for 30 min and then applied to the surface of the epoxy resin matrix by spraying. After pre-curing at room temperature for 24 h, it was cured at 65 °C for 12 h, and the resulting coating thickness was about 40 μm.

[0048] Comparative Example 1 Preparation of biomimetic cerium-based metal-organic framework nanozymes and their application in polyurethane coatings: (1) Weigh 0.4 mmol of cerium ammonium nitrate and dissolve it in 10 mL of deionized water to obtain a metal salt solution; (2) Dissolve 0.9 mmol of terephthalic acid in 30 mL of DMF to form a transparent ligand solution; (3) The metal salt solution was slowly added dropwise to the ligand solution. The volume ratio of the metal salt solution to the ligand solution was 1:3, the dropping rate was 0.5 mL / min, and the temperature was maintained at 25℃ for 10 min. (4) Place the mixed solution in a pressure-resistant tube and heat it in a water bath at 90°C for 1 hour. After the reaction is complete, cool it to room temperature, centrifuge to separate the product, and wash it three times with DMF and ethanol in sequence; (5) The product was vacuum dried at 65°C for 10 h to obtain white biomimetic cerium-based metal-organic framework nanozyme powder; (6) The obtained powder was added to the polyurethane resin system at 0.8 wt%, and 10% of the polyurethane resin mass of polyamide curing agent was added. After mechanical stirring for 30 min to mix evenly, the mixture was sprayed onto the surface of the epoxy resin matrix. After pre-curing at room temperature for 24 h, it was heat-cured at 70℃ for 12 h. The resulting coating thickness was about 30 μm, and the surface was smooth and dense.

[0049] Comparative Example 2 Preparation of biomimetic cerium-based metal-organic framework nanozymes and their application in polyvinylidene fluoride composite coatings: (1) Weigh 0.6 mmol of cerium ammonium nitrate and dissolve it in 12 mL of deionized water to obtain a metal salt solution; (2) Dissolve 0.36 mmol of tartaric acid in 36 mL of DMF and stir to form a ligand solution; (3) The metal salt solution and the ligand solution were slowly added dropwise to the ligand solution at a volume ratio of 1:3, with a dropping rate of 0.5 mL / min, and the temperature was maintained at 25℃ while stirring for 15 min. (4) The mixture was placed in a pressure-resistant tube and heated in an oven at 100°C for 0.5 h. After cooling, it was centrifuged and washed, and washed three times each with DMF and ethanol. (5) Drying conditions: 60℃ vacuum for 12h to obtain biomimetic cerium-based metal-organic framework nanoenzyme white powder; (6) The obtained powder was added to a polyvinylidene fluoride (PVDF) solution (15wt% PVDF / DMF solution) at 0.5wt%, and after being magnetically stirred for 30 min to achieve uniformity, it was spin-coated onto the surface of the epoxy resin matrix. After pre-curing at room temperature for 12 h, it was heat-cured at 60℃ for 24 h to obtain a transparent anti-fouling and anti-corrosion coating.

[0050] Comparative Example 3 Preparation of biomimetic cerium-based metal-organic framework nanozymes and their application in epoxy resin composite coatings: (1) Weigh 0.5 mmol of cerium ammonium nitrate and dissolve it in 10 mL of deionized water to obtain a light yellow transparent metal salt solution; (2) Take another 15 mL of DMF as a solvent, add 0.5 mmol of fumaric acid, and stir to form a ligand solution; (3) Under magnetic stirring, the metal salt solution was slowly added dropwise to the ligand solution at a rate of 1 mL / min, with a volume ratio of 1:3 between the metal salt solution and the ligand solution; after stirring and mixing at 25℃ for 15 min, a homogeneous light yellow complex solution was formed. (4) The obtained complex solution was transferred into a pressure-resistant tube and reacted in an oil bath at 100°C for 0.5 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, the precipitate was separated by centrifugation, and washed three times each with DMF, deionized water and acetone. (5) The product was placed in a vacuum at 60°C for 12 h to obtain a white powdery biomimetic cerium-based metal-organic framework nanozyme; (6) Add the obtained powder to the epoxy resin system at a ratio of 1.0 wt%, add 10% polyamide curing agent by weight of epoxy resin, ultrasonically disperse for 20 min and mix evenly, degas under vacuum and spin coat onto epoxy resin substrate. Pre-cure at room temperature for 12 h and then heat-cure at 70℃ for 12 h to form a composite coating with a thickness of about 25 μm that is anti-fouling and anti-corrosion.

[0051] Taking into account factors such as cost and time, Example 1 is preferred for conducting tests 1-2 and 5-7.

[0052] Test Example 1: Structural Characterization Analysis This invention uses transmission electron microscopy (TEM) and X-ray diffraction (XRD) to analyze the morphology and structure of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1. The results are as follows: Figure 1 , Figure 2 and Figure 3 As shown, where, Figure 1 Transmission electron microscopy of the biomimetic cerium-based metal-organic framework nanozyme in Example 1 of this invention; Figure 2 The particle size distribution diagram of the biomimetic cerium-based metal-organic framework nanozyme in Example 1 of this invention; Figure 3X-ray diffraction pattern of the biomimetic cerium-based metal-organic framework nanozyme in Example 1 of this invention.

[0053] Depend on Figure 1 and Figure 2 As can be seen, the Ce-MOF samples exhibit a uniformly dispersed quasi-spherical structure with abundant pores and grooves on the surface. The average particle size is approximately 10 nm, and the particles are uniformly distributed without obvious agglomeration. This pore structure facilitates substrate molecule diffusion and exposure of active sites, indicating that the solvothermal system used in this application can effectively control the crystal nucleus growth rate and obtain highly dispersed nanostructures. Particle size distribution analysis further shows that the obtained nanoparticles have a concentrated size distribution and complete surface morphology, reflecting the controllability of the system's reaction and the structural uniformity of the product.

[0054] Depend on Figure 3 It can be seen that the product has CeO2 characteristic diffraction peaks at 2θ=28.6°, 33.1°, and 47.5°, and at the same time, it produces new diffraction peaks with broad and low intensity, indicating that the metal ions and organic ligands have successfully constructed a stable MOF coordination framework and constructed a biomimetic MOF structure.

[0055] Test Example 2: Enzyme-like Catalytic Activity Test The biomimetic cerium-based metal-organic framework nanozyme (Ce-MOF) prepared in Example 1 was tested for halogenated peroxidase-like (HPO) and oxidase-like (OXD) activities to evaluate its multi-enzyme catalytic performance.

[0056] like Figure 4 As shown, in the HPO-like activity test, phenol red (PR) was used as the substrate, and bromide ions (Br) were... - Using halogen source (H₂O₂) and hydrogen peroxide (Ce-MOF) as oxidant, PR is progressively brominated to bromophenol blue (Br₄PR) under Ce-MOF catalysis. During the reaction, the solution color gradually changes from yellow to blue-violet, and the absorption peak shifts from 443 nm to 590 nm. With prolonged reaction time, the absorbance of Br₄PR at 590 nm continuously increases, while the characteristic peak of PR gradually weakens, indicating that the bromination reaction in the catalytic system continues and achieves complete conversion within approximately 24 hours.

[0057] In OXD-like activity testing, using 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate, Ce-MOF directly catalyzed its oxidation to a blue oxidation product (ox-TMB) under conditions without added H2O2, resulting in a significant absorption peak at 652 nm. In summary, the biomimetic cerium-based metal-organic framework nanozyme of this application possesses both HPO-like and OXD-like dual-enzyme catalytic activities, enabling the efficient generation of various reactive oxygen species and halogenated species under mild conditions. Its biomimetic coordination structure significantly enhances the catalytic rate and substrate affinity through electronic regulation and interfacial activation, providing a continuous and stable reaction driving force for achieving the synergistic antibacterial, antifouling, and anticorrosive functions of the material.

[0058] Test Example 3: Antibacterial Performance Test Gram-negative bacteria Escherichia coli ( Escherichia coli ) and Gram-positive bacteria Staphylococcus aureus ( Staphylococcus aureus As a model strain, the antibacterial properties of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 were tested.

[0059] During the experiment, Ce-MOF samples were dispersed in sterile phosphate-buffered saline (PBS) to prepare a suspension with a concentration of 0.1 mg / mL. The appropriate bacterial culture was then added (final concentration 10). 6 The Ce-MOF (CFU / mL) was mixed with the sample suspension and incubated at 37℃ for 4 hours. After incubation, samples were plated onto nutrient agar medium and incubated at 37℃ for 24 hours. Colony counts were performed after colony growth stabilized. The blank group consisted of a Ce-MOF-free bacterial suspension system. Ce-MOF / bacterial suspensions with added hydrogen peroxide / bromine ions and bacterial suspensions with added hydrogen peroxide / bromine ions were plated onto nutrient agar medium as control groups. The antibacterial rates of the biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2, and Comparative Examples 1-3 are shown in Table 1.

[0060] Table 1. Antibacterial rates of the biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2, and Comparative Examples 1-3. sample Antibacterial rate (%) Example 1 99.98% Example 2 95.18% Comparative Example 1 90.62% Comparative Example 2 81.05% Comparative Example 3 92.41% It can be seen that the biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2 and Comparative Examples 1-3 all exhibit good antibacterial effects. Among them, the coating obtained in Example 1 shows the best antibacterial rate, reaching 99.98%, which is close to complete antibacterial.

[0061] The comparison of the antibacterial properties of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of this invention against Escherichia coli and Staphylococcus aureus in different systems is shown in the figure below. Figure 5As shown in the figure, the blank group exhibits dense colony distribution and vigorous bacterial growth; while the experimental group with Ce-MOF sample added shows a significant reduction in colony count. The bacterial colony count in the bacterial solution with only hydrogen peroxide / bromine ion system added is slightly lower than that in the blank group, but significantly higher than that in the experimental group with Ce-MOF sample added. In contrast, the Ce-MOF group with hydrogen peroxide / bromine ion system added is almost completely inhibited. Statistical analysis shows that the antibacterial rate of the sample in Example 1 exceeds 99.9%. This result demonstrates that the biomimetic Ce-MOF nanozyme of this application can achieve highly efficient and broad-spectrum killing of both Gram-negative and Gram-positive bacteria.

[0062] In antibacterial performance tests, the Ce-MOF nanozyme prepared in this invention exhibited a dual catalytic mechanism and synergistic effect. Firstly, Ce-MOF itself possesses excellent oxidase-like activity, capable of catalyzing the generation of a certain amount of ROS without exogenous substrates, achieving a basic antibacterial effect. More importantly, in the presence of hydrogen peroxide and bromide ions in a simulated marine environment, Ce-MOF can efficiently exert halogen-like peroxidase activity, catalyzing the reaction of the two to generate hypobromoic acid, a highly oxidizing acid, thereby producing a strong bactericidal effect against both Gram-negative and Gram-positive bacteria. This technical solution does not rely on traditional biocides, is sustainable and environmentally friendly, and provides a green antibacterial method for integrated antifouling and anti-corrosion protection.

[0063] Test Example 4: Algae Resistance Test To further verify the antifouling performance of the biomimetic cerium-based metal-organic framework nanoenzyme of this application, a typical marine attached diatom, *Nyctaginosa*, was used. Nitzschia closterium f. minutissima Using as a model organism, anti-algal attachment experiments were conducted under controlled experimental conditions.

[0064] The biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2, and Comparative Examples 1-3 were used as the experimental group, and a blank group without Ce-MOF resin coating was also set up. Each sample was immersed in a culture medium during the logarithmic growth phase of algae and cultured statically at 25℃ under constant temperature and light conditions for 7 days. After cultivation, the sample surface was washed with deionized water, and the algal adhesion was observed using an optical microscope. The algal coverage was statistically analyzed. The algal resistance rates of the biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2, and Comparative Examples 1-3 are shown in Table 2.

[0065] Table 2. Algae resistance rates of the biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2, and Comparative Examples 1-3. sample Algae resistance rate (%) Example 1 95.11% Example 2 93.25% Comparative Example 1 88.47% Comparative Example 2 82.06% Comparative Example 3 90.92% It can be seen that the biomimetic cerium-based metal-organic framework nanoenzyme composite coatings prepared in Examples 1, 2 and Comparative Examples 1-3 all exhibit good anti-diatom adhesion effects. Among them, the coating obtained in Example 1 shows the best anti-algae rate, reaching 95.11%, which effectively inhibits diatom adhesion.

[0066] Comparison of optical microscopy and Image J images of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating prepared in Example 1 of this invention for anti-algae adhesion is shown in the figure below. Figure 6 As shown in the image, the blank group's resin coating surface exhibits significant algal adhesion, with dense algal distribution and vigorous growth; while the Ce-MOF-containing composite coating surface shows almost no visible algal growth, indicating a significant reduction in algal adhesion. Quantitative image analysis reveals that the algal coverage of the Ce-MOF-containing composite coating is significantly lower than that of the blank group, demonstrating its excellent anti-algal adhesion performance. These results indicate that the biomimetic Ce-MOF nanoenzyme composite coating of this application can effectively provide anti-algal adhesion performance.

[0067] Test Example 5: Coating Corrosion Resistance Test The corrosion resistance of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating prepared in Example 1 was tested using a copper (Cu) metal substrate as a control, and compared with a blank copper substrate sample. During the testing, each sample was placed in a 3.5 wt% NaCl solution, and electrochemical analysis was performed using a three-electrode system. The working electrode was the sample under test, the reference electrode was a saturated calomel electrode, and the counter electrode was a platinum sheet. The tests were conducted at room temperature. After the system stabilized, Tafel spectroscopy and electrochemical impedance spectroscopy (EIS) were performed to comprehensively evaluate the corrosion resistance and interfacial electrochemical characteristics of the samples. The macroscopic corrosion resistance was evaluated through acid and alkaline solution immersion experiments.

[0068] Figure 7 The image shows a comparison of the corrosion resistance of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating and a blank copper substrate in Example 1 of this invention; wherein, Figure 7 Image a shows a photograph of corrosion caused by acid and alkali solutions. Figure 7 b represents the potentiodynamic polarization curve. Figure 7 c is the electrochemical impedance spectroscopy.

[0069] Acid-base solution corrosion photographs revealed large-area corrosion products on the surface of the blank copper substrate sample, while the Ce-MOF-containing composite coating remained intact and dense, retaining a certain degree of hydrophobicity, with no visible corrosion pits or under-film desorption. Tafel curve analysis showed that the corrosion current density of the Ce-MOF-containing composite coating sample was significantly reduced, nearly two orders of magnitude lower than that of the blank copper substrate sample; the corrosion potential shifted positively compared to the blank sample, indicating a significant slowdown in the corrosion reaction kinetics of the coating system and effective protection of the metal surface. EIS testing further verified the excellent protective performance of the biomimetic cerium-based metal-organic framework nanoenzyme composite coating. The Nyquist plot showed that the Ce-MOF-containing sample exhibited a larger arc radius, indicating a significantly increased interfacial charge transfer impedance and stronger electrochemical shielding ability. Therefore, the Ce-MOF-containing nanoenzyme composite coating sample prepared in this application can effectively achieve anti-corrosion function.

[0070] Test Example 6: Long-term marine exposure test The biomimetic cerium-based metal-organic framework nanoenzyme composite coating sample prepared in Example 1 and the blank group resin coating sample were immersed in seawater for 60 days, and the surface bio-attachment was observed periodically (30 days / time).

[0071] (1) Exposure environment: Bohai Sea, Tianjin, China (117°46′E, 39°43′N), immersion depth 1m below sea level; (2) Take pictures every 30 days and calculate the adhesion rate using image analysis software.

[0072] The results are as follows Figure 8 As shown, the blank resin-coated samples exhibited significant algae and barnacle adhesion after 30 days, while the surface of the composite coating sample containing Ce-MOF nanozymes remained largely smooth. At 60 days, the surface contamination coverage of the blank resin-coated samples exceeded 70%, but the adhesion area of ​​the Ce-MOF nanozyme-containing composite coating sample remained below 5%. Therefore, the Ce-MOF nanozyme-containing composite coating sample prepared in this application possesses excellent long-term antibacterial, anti-algae, and anti-corrosion properties, maintaining stable protective effects in complex marine environments.

[0073] Test Example 7 To verify the biocompatibility of the biomimetic cerium-based metal-organic framework nanozyme of the present invention, the cell viability of the biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 of the present invention was evaluated by the Cell Counting Kit-8 (CCK-8) assay, and its cytotoxicity was characterized, including the following steps: Rat bone marrow mesenchymal stem cells (rBMSCs) were cultured in α-MEM medium supplemented with 10% fetal bovine serum and 1% penicillin-streptomycin at 37°C and 5% CO2. After reaching a suitable cell density, the cells were digested with 0.25% trypsin-EDTA and cultured at 5 × 10⁶ cells / well. 3 Cells were seeded at a density of 100 μL into 96-well plates and cultured for 24 h to allow for full adhesion. The biomimetic cerium-based metal-organic framework nanozyme prepared in Example 1 was prepared into a high-concentration stock solution using sterile PBS or complete culture medium. Before use, the stock solution was diluted to a series of working concentrations. Different concentrations of nanozyme working solution were directly added to the corresponding cell wells. After incubation for 24 h, 10 μL of CCK-8 reagent was added to each well, and incubation was continued at 37°C for 2 h. Subsequently, the absorbance of each well was measured at 450 nm using a microplate reader to assess cell viability.

[0074] Depend on Figure 9 As shown, the biomimetic cerium-based metal-organic framework nanozyme prepared in this invention exhibits excellent biocompatibility. Even at a high concentration of 200 μg / g, the cell viability remains >90%, demonstrating good biocompatibility and extremely low cytotoxicity. Combined with the proven broad-spectrum and highly efficient enzymatic catalytic antibacterial activity of this material, this safety data constitutes the core basis for its safe application in the biomedical field.

[0075] In summary, the biomimetic cerium-based metal-organic framework nanoenzyme and its antifouling and anticorrosion composite coating system of this application achieve multiple functions such as high efficiency in antibacterial, anti-algae, antifouling and anticorrosion in a single system through biomimetic coordination construction, multi-enzyme activity synergy and structural optimization design. The technical effect is significant and has broad application prospects and promotion value.

[0076] The biomimetic cerium-based metal-organic framework nanozyme prepared by this invention has certain effects in the field of marine antifouling coatings. Based on the same or similar antibacterial principles and properties and the experimental results shown in this invention, it is expected that it will also have certain antibacterial effects in the application of materials in the medical fields such as dental additives and disinfectants.

[0077] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a biomimetic cerium-based metal-organic framework nanozyme for an antifouling coating, characterized in that, Biomimetic cerium-based metal-organic framework nanozymes are used to prepare anti-corrosion, antibacterial, and algae-inhibiting antifouling coatings or medical antibacterial materials for marine environments. The preparation process includes the following steps: S1. Preparation of metal salt solution: Soluble cerium salts are dissolved in deionized water to obtain metal salt solutions; S2. Preparation of amino acid solution: Amino acids are dissolved in a polar organic solvent to obtain an amino acid solution; S3. Preparation of complexing solution: The metal salt solution obtained in step S1 is slowly added dropwise to the amino acid solution obtained in step S2, and the dropping rate is controlled at 0.5-1 mL / min. The mixture is stirred until homogeneous to obtain a complex solution. The temperature is maintained at 20-50℃ during the stirring process. S4, Solvothermal reaction: The complex solution obtained in step S3 was transferred to a container and heated at 60℃-120℃ for a solvothermal reaction for 0.1-2 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and centrifuged to obtain the precipitate. S5. Washing and drying: The precipitate obtained in step S4 was washed, and the washed product was placed in a vacuum drying oven and dried at 40℃-80℃ for 6-24h to obtain a biomimetic cerium-based metal-organic framework nanozyme.

2. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 1, characterized in that, In step S1, the soluble cerium salt is cerium ammonium nitrate, cerium nitrate, cerium sulfate, or cerium acetate.

3. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 1, characterized in that, In step S2, the polar organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, ethanol, N,N-dimethylacetamide or a mixed solvent system thereof, and the amino acid contains a dicarboxyl group structure.

4. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 3, characterized in that, The amino acid containing the dicarboxyl group is glutamic acid or aspartic acid.

5. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 1, characterized in that, In step S1, the concentration of the metal salt solution is 10-100 mmol / L; in step S2, the concentration of the amino acid solution is 5-100 mmol / L.

6. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 1, characterized in that, In step S3, the volume ratio of the metal salt solution to the amino acid solution is 1:1 to 1:

5.

7. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 1, characterized in that, In step S3, the dropping rate of the metal salt solution is 0.5 mL / min; in step S4, the reaction temperature of the solvothermal reaction is 80℃-110℃, the reaction time is 0.5-1h, and the heating method is one of oil bath, water bath or oven heating.

8. The method for preparing biomimetic cerium-based metal-organic framework nanozymes for antifouling coatings as described in claim 1, characterized in that, In step S5, the precipitate is washed three times each with one or more of N,N-dimethylformamide, deionized water, ethanol, and acetone. The drying conditions are drying at 60℃-70℃ for 10-12 hours.

9. A biomimetic cerium-based metal-organic framework nanozyme for antifouling coating prepared by the preparation method according to any one of claims 1-8.

10. The application of the biomimetic cerium-based metal-organic framework nanozyme for antifouling coating as described in claim 9 in the preparation of antifouling and anticorrosive materials for marine environments and medical antibacterial materials.

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