A covalent organic framework composite material, a preparation method thereof and application thereof in preparation of antibacterial products

Abstract

This invention discloses a covalent organic framework composite material, its preparation method, and its application in the preparation of antibacterial products. It belongs to the field of functional materials technology. This invention uses crystalline covalent organic frameworks synthesized from triporphyrin, perylene imide, or nitrogen-containing heterocyclic building blocks and chitosan to prepare a covalent organic framework composite material. It is a composite material with efficient, long-lasting, and broad-spectrum antibacterial properties. This composite material can overcome the defect that COF powder is difficult to apply directly and expand the antibacterial spectrum and efficacy of chitosan materials.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, and particularly relates to a covalent organic framework composite material, its preparation method, and its application in the preparation of antibacterial products. Background Technology

[0002] Bacterial infections pose a persistent and significant threat to global public health. With the increasing prevalence of antibiotic overuse and misuse, multidrug-resistant bacteria and even "superbugs" are emerging, drastically reducing the effectiveness of traditional antibiotic therapies and posing a severe challenge to clinical treatment. Therefore, developing novel antimicrobial strategies and materials that do not rely on the mechanisms of action of traditional antibiotics and can effectively overcome drug resistance has become an urgent need and a cutting-edge research direction in the fields of biomedicine, materials science, and public health.

[0003] Covalent organic frameworks (COFs) have attracted widespread attention due to their unique advantages. COFs are a class of porous crystalline polymers composed of lightweight organic molecular units linked by strong covalent bonds. Through the rational design and selection of precursor molecules, the pore size, channel shape, surface chemical environment, and photoelectric properties of COFs can be precisely controlled. In particular, by introducing building blocks with excellent photoactivity, such as triphenylamine, porphyrin, and perylene imide, photosensitive COFs that can efficiently generate reactive oxygen species (ROS) under visible and even near-infrared light irradiation can be synthesized. These ROS can irreversibly oxidize and destroy bacterial cell membranes, proteins, and genetic material, achieving highly efficient photodynamic antibacterial activity without easily inducing bacterial resistance.

[0004] However, when translating these superior properties into practical applications, powdered COFs reveal significant limitations. For example, their loose, shapeless powder state makes them difficult to directly mold and fix for specific applications, preventing their use as standalone wound dressings. These processing and molding bottlenecks severely hinder the practical application and promotion of COF materials in the antibacterial field.

[0005] Overcoming the morphological defects of COFs and combining their excellent intrinsic properties with practical material forms has become the key to promoting their practical application. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a covalent organic framework composite material, its preparation method, and its application in the preparation of antibacterial products. The covalent organic framework composite material of this invention is a composite material with efficient, long-lasting, and broad-spectrum antibacterial properties. This composite material overcomes the limitation of direct application of COF powders and expands the antibacterial spectrum of chitosan materials, thereby improving antibacterial efficacy.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a covalent organic framework composite material comprising a covalent organic framework (COFs) and a chitosan matrix; The covalent organic framework is a crystalline covalent organic framework synthesized from building units of triporphyrins, perylene imides, or nitrogen-containing heterocycles. The covalent organic framework constitutes 30-60% of the mass of the covalent organic framework composite material.

[0008] This invention combines COFs with a biocompatible and processable polymer matrix (chitosan) to construct a structurally stable, morphologically controllable, and functionally synergistic composite antibacterial material. This composite material not only effectively disperses and immobilizes COF particles, preventing their aggregation and loss, but also, through the synergistic effect of the matrix and by imparting diverse macroscopic morphologies such as injectability, film formation, and gelation, it can meet the personalized needs of different application scenarios such as wound healing, surface coating, and filtration purification.

[0009] Furthermore, the preparation method of the covalent organic framework includes the following steps: mixing Ag3L3, 4,4'-dithiodiphenylamine, benzyl alcohol, o-dichlorobenzene and an aqueous solution of acetic acid, freezing in a liquid nitrogen bath, degassing after at least three freeze-thaw cycles, heating to room temperature for ultrasonic and microwave treatment, heating reaction, centrifugation, solvent exchange and drying to obtain the covalent organic framework.

[0010] Furthermore, the ratio of the aqueous solutions of Ag3L3, 4,4'-dithiodiphenylamine, benzyl alcohol, o-dichlorobenzene and acetic acid is 0.05 mmol:0.075 mmol:0.5 mL:0.5 mL:0.3 mL.

[0011] Furthermore, the concentration of the aqueous acetic acid solution is 6 M.

[0012] Furthermore, the covalent organic framework composite material includes a covalent organic framework composite gel and a covalent organic framework composite film.

[0013] The present invention also provides a method for preparing the above-mentioned covalent organic framework composite material, comprising the following steps: adding the covalent organic framework to an acidic aqueous solution of chitosan, stirring evenly, and ultrasonically treating to obtain a black dispersion; When the covalent organic framework composite material is a covalent organic framework composite gel, the dispersion is first pre-frozen and then freeze-dried to obtain the covalent organic framework composite gel. When the covalent organic framework composite material is a covalent organic framework composite film, the dispersion is poured onto a substrate and a film is formed by casting to obtain the covalent organic framework composite film.

[0014] Furthermore, the method for preparing the chitosan acidic aqueous solution is as follows: chitosan, acetic acid and water are mixed and stirred evenly to obtain the chitosan acidic aqueous solution.

[0015] Furthermore, the ratio of chitosan, acetic acid, and water is 33 mg: 12 μL: 1.0 mL.

[0016] Furthermore, the pre-freezing temperature is -80 ℃.

[0017] This invention also provides the application of the above-mentioned covalent organic framework composite material in the preparation of antibacterial products.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: Clear functional orientation: This invention selects specific COFs with excellent photo-dual-mode antibacterial activity that have been previously verified as functional units, ensuring the traceability of the source of composite material performance and the clear structural advantages.

[0019] High performance and broad spectrum: The composite material inherits and synergistically combines the high antibacterial properties of COFs with the inherent antibacterial properties and biocompatibility of chitosan, and is effective against Gram-positive bacteria (such as... S. aureus ) and Gram-negative bacteria (such as E. coli All of them exhibited strong killing effects and have the potential to be enhanced by light.

[0020] Diverse and practical forms: Through simple processes, composite materials can be processed into a variety of practical forms such as aerogels (with high specific surface area, suitable for filtration, adsorption and healing) and films (suitable for packaging, coatings and dressings), which greatly expands the application scenarios.

[0021] The preparation process is simple and environmentally friendly: the entire preparation process is mainly carried out in the aqueous phase, under mild conditions, without the need for complex equipment, and is suitable for large-scale production.

[0022] Improved stability and durability: By immobilizing COFs within the chitosan three-dimensional network, the shedding and loss of nanoparticles are effectively prevented, thereby improving the stability and antibacterial durability of the material. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is the powder diffraction (XRD) pattern of the COFs prepared in Example 1 of this invention; Figure 2 This is a scanning electron microscope (SEM) image of the COFs prepared in Example 1 of this invention; Figure 3The infrared absorption spectrum (IR) of the COFs prepared in Example 1 of this invention; Figure 4 The specific surface area adsorption (BET) curves of the COFs prepared in Example 1 of this invention are shown. Figure 5 Thermogravimetric analysis (TGA) curves of COFs prepared in Example 1 of this invention; Figure 6 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the COFs prepared in Example 1 of this invention. Figure 7 The electron paramagnetic resonance (EPR) spectrum of the COFs prepared in Example 1 of this invention is shown. Figure 8 The COFs prepared in Example 1 of this invention are... S. aureus The antibacterial efficiency; Figure 9 The COFs prepared in Example 1 of this invention are... E. coli The antibacterial efficiency; Figure 10 Digital photographs and SEM images of the COFs@chitosan composite aerogel prepared in Example 2 of this invention; Figure 11 The TGA curve of the COFs@chitosan composite aerogel prepared in Example 2 of this invention; Figure 12 Digital photographs and cross-sectional SEM images of the COFs@chitosan composite film prepared in Example 3 of this invention; Figure 13 The blank control group, pure chitosan material, and the covalent organic framework composite material (including covalent organic framework composite gel and covalent organic framework composite film) prepared in this invention were compared with those of the present invention. S. aureus The antibacterial efficiency is given by: 0 mg / mL representing the blank control group, 0.5 mg / mL pure chitosan material representing pure chitosan material, and 0.5 mg / mL covalent organic framework composite material representing the covalent organic framework composite material prepared in this invention. Figure 14 The blank control group, pure chitosan material, and the covalent organic framework composite material (including covalent organic framework composite gel and covalent organic framework composite film) prepared in this invention were compared with those of the present invention. E. coli The antibacterial efficiency is given by: 0 mg / mL representing the blank control group, 0.5 mg / mL pure chitosan material representing pure chitosan material, and 0.5 mg / mL covalent organic framework composite material representing the covalent organic framework composite material prepared in this invention. Figure 15 The results of the cytotoxicity test of the COFs@chitosan composite aerogel prepared in Example 2 of this invention; Figure 16 The images show the stability and durability verification results of the COFs@chitosan composite aerogel prepared in Example 2 of this invention. The left side shows the SEM image of the COFs@chitosan composite aerogel after 5 cycles, and the right side shows the antibacterial efficiency verification results. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] An embodiment of the present invention provides a covalent organic framework composite material comprising a covalent organic framework (COFs) and a chitosan matrix; Covalent organic frameworks are crystalline covalent organic frameworks synthesized from building units of triporphyrins, perylene imides, or nitrogen-containing heterocycles. The mass percentage of COFs in covalent organic framework composites is 30-60%.

[0030] The covalent organic framework in this invention is a photoactive COF material, which, when existing independently, exhibits activity against Escherichia coli (E. coli) under light conditions. E. coli ) and Staphylococcus aureus ( S. aureus The kill rate of all of them is no less than 90% (preferably no less than 95%).

[0031] In a preferred embodiment of the present invention, the method for preparing a covalent organic framework includes the following steps: mixing Ag3L3, 4,4'-dithiodiphenylamine, benzyl alcohol, o-dichlorobenzene and an aqueous solution of acetic acid, freezing in a liquid nitrogen bath, degassing after at least three freeze-thaw cycles, heating to room temperature for ultrasonic and microwave treatment, heating reaction, centrifugation, solvent exchange and drying to obtain a covalent organic framework.

[0032] In a preferred embodiment of the present invention, a freeze-thaw cycle refers to freezing the tube in liquid nitrogen for 3 minutes, followed by thawing the tube in a beaker containing anhydrous ethanol.

[0033] In a preferred embodiment of the present invention, the ratio of the amounts of Ag3L3, 4,4'-dithiodiphenylamine, benzyl alcohol, o-dichlorobenzene and aqueous acetic acid is 0.05 mmol: 0.075 mmol: 0.5 mL: 0.5 mL: 0.3 mL.

[0034] In a preferred embodiment of the present invention, the concentration of the aqueous acetic acid solution is 6 M.

[0035] An exemplary method for preparing covalent organic frameworks is as follows: Ag3L3 (30.45 mg, 0.05 mmol), 4,4'-dithiodiphenylamine (18.63 mg, 0.075 mmol), benzyl alcohol (0.5 mL), o-dichlorobenzene (0.5 mL), and 0.3 mL of 6M acetic acid aqueous solution are loaded into a Schlenk tube. The tube is then rapidly frozen in a liquid nitrogen bath at 77 K, degassed by three freeze-thaw cycles, heated to room temperature, and subjected to ultrasonic and microwave treatment for 30 min. After the reaction is completed, a yellow-brown solid is obtained by centrifugation, and the solid is exchanged with anhydrous ethanol three times. The obtained product is then vacuum dried at 26 ℃ for 8 h to obtain a yellow-brown powdery solid, which is a covalent organic framework (COFs).

[0036] In a preferred embodiment of the present invention, the covalent organic framework composite material includes a covalent organic framework composite gel and a covalent organic framework composite film.

[0037] The embodiments of the present invention also provide a method for preparing the above-mentioned covalent organic framework composite material, comprising the following steps: adding the covalent organic framework to an acidic aqueous solution of chitosan, stirring evenly, and ultrasonically treating to obtain a black dispersion; When the covalent organic framework composite material is a covalent organic framework composite gel, the dispersion is first pre-frozen and then freeze-dried to obtain the covalent organic framework composite gel. When the covalent organic framework composite material is a covalent organic framework composite film, the dispersion is poured onto the substrate and a film is formed by casting.

[0038] For example, the substrate is a polytetrafluoroethylene sheet.

[0039] In a preferred embodiment of the present invention, the method for preparing the acidic aqueous solution of chitosan is as follows: chitosan, acetic acid and water are mixed and stirred evenly to obtain an acidic aqueous solution of chitosan.

[0040] In a preferred embodiment of the present invention, the ratio of chitosan, acetic acid and water is 33 mg: 12 μL: 1.0 mL.

[0041] In a preferred embodiment of the present invention, the pre-freezing temperature is -80 °C.

[0042] For example, when the covalent organic framework composite material is a covalent organic framework composite film, the preparation method is as follows: add covalent organic framework (COFs, 33 mg) to an acidic aqueous solution of chitosan (33 mg chitosan, 12 μL acetic acid and 1.0 mL deionized water) and stir magnetically at room temperature for 12 h, and sonicate for 60 minutes to obtain a uniform black dispersion; pour the above dispersion onto a flat polytetrafluoroethylene plate, cast it into a film at room temperature, and dry it in an oven at 40 ℃ for 24 hours. After drying, peel off the film, and the resulting flexible composite film is the covalent organic framework composite film, which is a COFs@chitosan composite film.

[0043] For example, when the covalent organic framework composite material is a covalent organic framework composite gel, the preparation method is as follows: the covalent organic framework (COFs, 33 mg) is added to an acidic aqueous solution of chitosan (33 mg chitosan, 12 μL acetic acid and 1.0 mL deionized water) and magnetically stirred at room temperature for 12 h, and ultrasonically treated for 60 minutes to obtain a uniform black dispersion; the above dispersion is poured into a mold, pre-frozen in a -80 ℃ freezer for 12 h, and then transferred to a freeze dryer for freeze drying for 48 h to obtain a covalent organic framework composite gel, which is a COFs@chitosan composite aerogel.

[0044] Embodiments of the present invention also provide the application of the above-described covalent organic framework composite material in the preparation of antibacterial products.

[0045] In a preferred embodiment of the present invention, the antibacterial products include: wound dressings, medical coatings, food packaging films, air or water filtration materials, and antibacterial finishing agents for textiles.

[0046] In this invention, the preparation method of pure chitosan aerogel is as follows: an acidic aqueous solution of chitosan (33 mg chitosan, 12 μL acetic acid and 1.0 mL deionized water) is magnetically stirred at room temperature for 12 h and ultrasonically treated for 60 min to obtain a uniform dispersion; the above dispersion is poured into a mold, pre-frozen in a -80 ℃ freezer for 12 h, and then transferred to a freeze dryer for freeze drying for 48 h to obtain the pure chitosan gel.

[0047] The preparation method of pure chitosan film is as follows: Chitosan acidic aqueous solution (33 mg chitosan, 12 μL acetic acid and 1.0 mL deionized water) is magnetically stirred at room temperature for 12 h and ultrasonically treated for 60 minutes to obtain a uniform dispersion; the above dispersion is poured onto a flat polytetrafluoroethylene plate, cast into a film at room temperature, and dried in an oven at 40 ℃ for 24 hours. The film is then peeled off, and the resulting composite film is the pure chitosan film.

[0048] Advantages of this invention: This invention constructs a multifunctional Ag NP@COFs-chitosan composite antibacterial system, achieving synergistic optimization of antibacterial performance and biosafety. A coordination pre-assembly strategy is employed: Ag... + Ag is pre-anchored to the organic monomer structure via coordination bonds, and Ag is simultaneously formed during the COF framework formation process. + In-situ reduction and confined growth of nanoparticles. This "three birds with one stone" design not only utilizes the spatial confinement effect of COF channels to obtain uniform (<5 nm) and stably dispersed Ag nanoparticles, effectively increasing their specific surface area and antibacterial active site density, but also significantly reduces Ag through the physical binding effect of the COF framework. + The non-specific release of this material resolves the contradiction between the biotoxicity and antibacterial efficiency of traditional Ag nanomaterials. Cytotoxicity experiments show that the composite material of this invention exhibits good biocompatibility. This is because the Ag ions coordinated through coordination can achieve good dispersibility and low toxicity through the action of COF, providing a foundation for in vivo antibacterial applications.

[0049] This invention overcomes the limitations of a single antibacterial mechanism by introducing a photosensitive molecular unit into the system. Under visible light excitation, the photosensitive molecule generates reactive oxygen species through a Type I / II mechanism, which then react with Ag. + The metal ion effect creates a synergistic antibacterial effect. Experimental data show that the composite material of this invention has a high antibacterial rate, confirming the significant enhancing effect of the photodynamic-metal ion synergistic effect.

[0050] This invention integrates COFs with chitosan in a multifunctional way. As a natural cationic polysaccharide matrix, chitosan forms a stable composite structure with COFs through electrostatic interactions. Its film-forming properties and processability enable the composite material to have a variety of macroscopic morphologies, extending to diverse medical applications such as wound dressings and catheter coatings.

[0051] The "antibacterial-anti-inflammatory-repair" three-in-one design concept of this invention enables the composite material to show great application potential in the fields of chronic wound treatment and anti-infection of implanted devices, and provides new ideas for the design of multifunctional nano-antibacterial materials.

[0052] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0053] The raw materials used in the embodiments of this invention were obtained from literature or by purchasing commercially available materials. For example, Ag3L3 was synthesized according to the literature Li, F., Zhu, J., Sun, P. et al. Highly efficient and selective extraction of gold by reduced graphene oxide. Nat Commun 13, 4472 (2022).

[0054] It should be noted that any aspects not described in detail in this invention are conventional practices in the art and are not the focus of this invention. For example, S. aureus bacteria or E. coli The specific methods, such as the method for culturing bacteria to the logarithmic growth phase and the method for sterilizing COF mixtures, were all completed using conventional methods.

[0055] The technical solution of the present invention will be further illustrated by the following embodiments.

[0056] Example 1 A method for preparing a covalent organic framework, comprising the following steps: Ag3L3 (30.45 mg, 0.05 mmol), 4,4'-dithiodiphenylamine (18.63 mg, 0.075 mmol), benzyl alcohol (0.5 mL), o-dichlorobenzene (0.5 mL), and 0.3 mL of 6M acetic acid aqueous solution were loaded into a Schlenk tube. The tube was rapidly frozen in a liquid nitrogen bath at 77 K until the liquid was completely frozen. After the liquid was frozen, the vacuum pump was turned on and turned off after 15 min. The tube was then placed in anhydrous ethanol to thaw. After three freeze-thaw cycles to degas the liquid, the tube was heated to room temperature and then subjected to ultrasonic and microwave treatment for 30 min. The tube was then heated at 65 °C for 8 h. After the reaction was completed, a yellow-brown solid was obtained by centrifugation and solvent exchanged three times with anhydrous ethanol. The product was then vacuum dried at 26 °C for 8 h to obtain a yellow-brown powdery solid, which is a covalent organic framework, denoted as COFs. This COFs are crystalline COFs synthesized by using Ag3L3 and 4,4'-dithiodiphenylamine as building blocks.

[0057] The powder diffraction (XRD) pattern of the COFs prepared in this embodiment is shown below. Figure 1 As shown, the scanning electron microscope (SEM) image is as follows. Figure 2 As shown, Figure 1 and Figure 2 This invention demonstrates that the COFs prepared in this invention are rod-shaped crystalline COFs materials; IR testing confirms the successful formation of imine bonds in the COFs prepared in this invention. Figure 3 ).

[0058] BET curves demonstrate that the obtained COFs have high porosity. Figure 4 The thermogravimetric analysis (TGA) curves of the COFs prepared in this embodiment are as follows: Figure 5 As shown, the X-ray photoelectron spectroscopy (XPS) spectrum is as follows: Figure 6 As shown, Figure 5 and Figure 6 This demonstrates that the COFs prepared by this invention possess certain thermal stability and that the silver in the COFs exists in elemental form. Furthermore, electron paramagnetic resonance (EPR) spectroscopy was performed on the COFs prepared in this embodiment, and the results are shown below. Figure 7 This demonstrates that COFs have good photodynamic potential.

[0059] Test Example 1: Antibacterial test of COFs (using COFs prepared in Example 1 as an example) Take the cultured to the logarithmic growth phase S. aureus Bacterial solution (1 mL 10) 8 (CFU / mL) or E. coli bacterial suspension (1 mL 10) 8The CFU / mL solution was mixed thoroughly with 1 mL of sterilized COFs mixture (concentrations of 0 (i.e., a mixture of bacterial culture and empty LB agar plates) and 0.5 mg / mL. A light source (xenon lamp, intensity 51.5 mW / cm²) was then applied. 2 Irradiation for 60 min). Every 15 min, 100 μL of the mixture was taken, diluted 10,000 times, spread on LB agar plates, and incubated at 37 ℃ for 12 h before counting the colonies.

[0060] like Figures 8-9 As shown, under light conditions, the kill rate was greater than 99%, demonstrating that these COFs possess excellent photo-antibacterial activity.

[0061] Example 2 A method for preparing a covalent organic framework composite gel, comprising the following steps: The COFs (33 mg) from Example 1 were added to an acidic aqueous solution of chitosan (33 mg chitosan, 12 μL acetic acid and 1.0 mL deionized water) and stirred magnetically at room temperature for 12 h, followed by ultrasonic treatment for 60 min to obtain a uniform black dispersion. The above dispersion was poured into a mold and pre-frozen in a -80 ℃ freezer for 12 h. Then it was transferred to a freeze dryer and freeze-dried at -50 ℃ for 48 h to obtain a covalent organic framework composite gel, which is a COFs@chitosan composite aerogel.

[0062] Digital photographs and SEM images of the COFs@chitosan composite aerogel prepared in this embodiment are shown below. Figure 10 As shown in the figure, SEM reveals that COFs particles are uniformly distributed in the COFs@chitosan composite aerogel. The TGA curve of the COFs@chitosan composite aerogel prepared in this embodiment is shown in the figure. Figure 11 As shown, the TGA curves demonstrate that the COFs@chitosan composite aerogel is relatively stable below 150℃.

[0063] Example 3 A method for preparing a covalent organic framework composite thin film, comprising the following steps: The COFs (33 mg) from Example 1 were added to an acidic aqueous solution of chitosan (33 mg chitosan, 12 μL acetic acid and 1.0 mL deionized water) and stirred magnetically at room temperature for 12 h, followed by ultrasonic treatment for 60 min to obtain a uniform black dispersion. The above dispersion was poured onto a flat polytetrafluoroethylene plate and cast into a film at room temperature. The film was then dried in an oven at 40 °C for 24 hours. The film was then peeled off, and the resulting flexible composite film was a covalent organic framework composite film, which is a COFs@chitosan composite film.

[0064] Digital photographs and cross-sectional SEM images of the COFs@chitosan composite film prepared in this embodiment are shown below. Figure 12 As shown in the figure, cross-sectional SEM reveals that COFs particles are uniformly distributed inside the film.

[0065] Test Example 2: Antibacterial performance test of covalent organic framework composite material (taking the COFs@chitosan composite film prepared in Example 3 as an example (it should be noted that there is no significant difference in antibacterial performance between the covalent organic framework composite gel and the covalent organic framework composite film)). Testing the effects of covalent organic framework composite materials (Example 3: covalent organic framework composite film) on... S. aureus and E. coli The antibacterial properties of the bacterial culture were assessed and compared with those of the blank control group and the pure chitosan material group. The specific procedure was as follows: Under light conditions, the covalent organic framework composite film and pure chitosan material from Example 3 were mixed with 1 ml of LB medium and then added to... S. aureus Bacterial solution (1 mL 10) 8 (CFU / mL) or E. coli Bacterial solution (1 mL 10) 8 Add 2 mL of the mixture to a simulated daylight xenon lamp (with a light density of 51.5 mw / cm²) to ensure the concentration is consistent with the pure COFs added to the bacterial culture. 3 At 15 min, 100 μL of the mixture was taken, diluted 10,000 times, and spread on LB agar plates. The plates were then incubated at 37 °C for 12 h before the colony count was determined.

[0066] The COFs@chitosan composite material prepared in this invention (using a covalent organic framework composite film as an example for illustration; it should be noted that there is no significant difference in antibacterial properties between the covalent organic framework composite gel and the covalent organic framework composite film) has the following effects: S. aureus Antibacterial efficiency and E. coli The antibacterial efficiencies are respectively as follows: Figure 13 and Figure 14 As shown, the covalent organic framework composite materials (including covalent organic framework composite gel and covalent organic framework composite film) prepared by the present invention have significantly higher antibacterial rates than the blank control group and the pure chitosan material group under light irradiation conditions, and are close to or even reach the level of pure COF powder, proving that the activity is effectively maintained after composite.

[0067] Test Example 3: Cytotoxicity Test of Composite Materials L929 cell suspension (100 μL, approximately 5000 cells / well) was seeded in 96-well plates and incubated at 37°C in a 5% CO2 incubator for 24 h. After discarding the culture medium, 100 μL of cell maintenance medium (1640 medium containing 2% fetal bovine serum) containing different concentration gradients of COF@chitosan aerogel (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 mg / mL) was added to each well, and the plates were incubated for 4–6 h. The mixed solution was then discarded. After washing the samples with PBS, 90 μL of cell maintenance medium was added to each well, followed by 10 μL of LCK-8 reagent. The plates were incubated for a total of 30 min, with each sample incubated six times. The absorbance was measured at 450 nm using a microplate reader. Figure 15 As shown, experiments demonstrate that the COFs@chitosan composite aerogel in Example 2 has excellent biocompatibility and can be used as a wound dressing, medical coating, food packaging film, air or water filtration material, textile antibacterial finishing agent, and other bio-antibacterial materials.

[0068] Figure 16 The image shows the stability and durability verification results of the COFs@chitosan composite aerogel prepared in Example 2 of this invention. The left side shows the SEM image of the COFs@chitosan composite aerogel after 5 cycles, and the right side shows the antibacterial efficiency verification results. It can be seen that the covalent organic framework composite material prepared by this invention has good stability and durability.

[0069] The cytotoxicity test results of the COFs@chitosan composite film prepared in Example 3 were not significantly different from those of the COFs@chitosan composite aerogel in Example 2, and therefore will not be listed separately. This indicates that the COFs@chitosan composite film in Example 2 has excellent biocompatibility and can also be used as a wound dressing, medical coating, food packaging film, air or water filtration material, antibacterial finishing agent for textiles, and other bio-antibacterial materials.

[0070] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A covalent organic framework composite material, characterized in that, Including covalent organic frameworks and chitosan matrix; The covalent organic framework is a crystalline covalent organic framework synthesized from building units of triporphyrins, perylene imides, or nitrogen-containing heterocycles. The covalent organic framework constitutes 30-60% of the mass of the covalent organic framework composite material.

2. The covalent organic framework composite material according to claim 1, characterized in that, The method for preparing the covalent organic framework includes the following steps: mixing Ag3L3, 4,4'-dithiodiphenylamine, benzyl alcohol, o-dichlorobenzene and an aqueous solution of acetic acid, freezing in a liquid nitrogen bath, degassing after at least three freeze-thaw cycles, heating to room temperature for ultrasonic and microwave treatment, heating reaction, centrifugation, solvent exchange and drying to obtain the covalent organic framework.

3. The covalent organic framework composite material according to claim 2, characterized in that, The ratio of the aqueous solutions of Ag3L3, 4,4'-dithiodiphenylamine, benzyl alcohol, o-dichlorobenzene and acetic acid is 0.05 mmol: 0.075 mmol: 0.5 mL: 0.5 mL: 0.3 mL.

4. The covalent organic framework composite material according to claim 3, characterized in that, The concentration of the acetic acid aqueous solution is 6 M.

5. The covalent organic framework composite material according to claim 1, characterized in that, The covalent organic framework composite material includes covalent organic framework composite gel and covalent organic framework composite film.

6. A method for preparing a covalent organic framework composite material according to any one of claims 1-5, characterized in that, The process includes the following steps: adding a covalent organic framework to an acidic aqueous solution of chitosan, stirring until homogeneous, and then sonicating to obtain a dispersion; When the covalent organic framework composite material is a covalent organic framework composite gel, the dispersion is first pre-frozen and then freeze-dried to obtain the covalent organic framework composite gel. When the covalent organic framework composite material is a covalent organic framework composite film, the dispersion is poured onto a substrate and a film is formed by casting to obtain the covalent organic framework composite film.

7. The method for preparing the covalent organic framework composite material according to claim 6, characterized in that, The method for preparing the acidic aqueous solution of chitosan is as follows: chitosan, acetic acid and water are mixed and stirred evenly to obtain the acidic aqueous solution of chitosan.

8. The method for preparing the covalent organic framework composite material according to claim 7, characterized in that, The ratio of chitosan, acetic acid, and water is 33 mg: 12 μL: 1.0 mL.

9. The method for preparing the covalent organic framework composite material according to claim 6, characterized in that, The pre-freezing temperature is -80 ℃.

10. The use of a covalent organic framework composite material as described in any one of claims 1-5 in the preparation of antibacterial products.

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