A nanocomposite, multifunctional antibacterial hydrogel and a preparation method and application thereof

Abstract

The application provides a kind of nanocomposite, multifunctional antibacterial hydrogel and its preparation method and application, belong to the technical field of biomedical materials.The application mixes carbon nanotube and 1,3,5-tri (4-aminophenyl) benzene, carries out first reaction, then mixes with 2,5-dimethoxy benzene-1,4-dimethyl formaldehyde, acetic acid solution, carries out second reaction, after second reaction is finished, the precipitate is collected, the precipitate is washed, dried to obtain imine COF material;The imine COF material and the ethanol solution containing iron ions are mixed, ultrasonic, stirring, the precipitate is collected, the precipitate is washed, dried to obtain nanocomposite.Oxidized dextran solution is sequentially mixed with the nanocomposite, coffee acid grafted chitosan solution, and the multifunctional antibacterial hydrogel is obtained by gelation.The nanocomposite and the multifunctional antibacterial hydrogel can be used for synergistic killing of bacteria in infected wounds and regulation and repair of wound microenvironment.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, and particularly relates to a nanocomposite, a multifunctional antibacterial hydrogel, its preparation method and application. Background Technology

[0002] Currently, antibiotics are the most widely used treatment for bacterial infections. However, antibiotic resistance in bacteria exacerbates the difficulty of treating bacterial infections. Therefore, infections induced by multidrug-resistant bacteria are becoming a significant challenge in clinical treatment. Researchers are continuously making efforts to combat drug-resistant bacteria and biofilm infections, such as developing novel antibacterial drugs, researching resistance inhibitors, and designing novel antibacterial strategies. Notably, nanomaterials show great promise in the biomedical field (including antibacterial applications), especially photoactive antibacterial nanomaterials. Their photothermal or photodynamic bacterial killing mechanisms offer excellent controllability and high antibacterial activity against drug-resistant bacteria, providing a significant advantage in combating bacterial infections.

[0003] Photothermal therapy (PTT) and photodynamic therapy (PDT) have attracted widespread attention as two powerful treatments for bacterial infections. Both involve using photosensitizers with strong light absorption properties to effectively convert light energy into heat or generate toxic reactive oxygen species (ROS) to kill bacteria, respectively. However, the use of PTT and PDT alone still has certain limitations. Therefore, there is a need to find a biomaterial that integrates chemokinetic therapy (CDT), photothermal therapy (PTT), and photodynamic therapy (PDT) for antibacterial treatment.

[0004] Covalent-organic frameworks (COFs) are a class of crystalline, porous organic framework materials formed by two or more organic molecules linked by covalent bonds. COFs mainly include boron-containing COFs, imine-containing COFs, triazine-containing COFs, and other types of COFs. As an emerging organic semiconductor, they can generate reactive oxygen species (ROS) through photoexcitation for antibacterial therapy, particularly for killing drug-resistant bacteria, and have attracted increasing attention in the field of photodynamic antibacterial therapy. However, as a polymer, COFs suffer from high exciton binding energies, which hinder the separation of photogenerated electron-hole pairs. Furthermore, COFs have limited catalytic sites and weak activity, thus limiting their photocatalytic or photodynamic efficiency. In addition, conventional COF materials have limited functionality and lack the ability to synergistically regulate the wound microenvironment (such as alleviating hypoxia and promoting cell proliferation). Moreover, conventional COF nanomaterials often require fixation with wound dressings in practical wound healing applications, making them inconvenient to use. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a nanocomposite, a multifunctional antibacterial hydrogel, its preparation method and application, to solve the problems of poor antibacterial ability, lack of wound microenvironment regulation ability and inconvenience of use of existing COF materials, and to provide a new material and technology for the treatment of bacterial infected wounds.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a nanocomposite, comprising the following steps:

[0008] 1) Carbon oxide nanotubes and 1,3,5-tris(4-aminophenyl)benzene were mixed to carry out the first reaction, and then mixed with 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and acetic acid solution to carry out the second reaction. After the second reaction was completed, the precipitate was collected, and the precipitate was washed and dried to obtain imine COF material.

[0009] 2) The imine COF material and an ethanol solution containing iron ions are mixed, ultrasonicated and stirred, the precipitate is collected, and the precipitate is washed and dried to obtain the nanocomposite.

[0010] Preferably, the mass ratio of the carbon oxide nanotubes to 1,3,5-tris(4-aminophenyl)benzene is 0.1-0.6 mg : 0.6-1.0 mg;

[0011] The mass-to-volume ratio of the carbon nanotubes, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and acetic acid solution is 0.1-0.6 mg: 0.8-1.2 mg: 400-600 μL.

[0012] Preferably, in step 1), the temperature of the first reaction is 20-30℃; the time of the first reaction is 40-80 min; the temperature of the second reaction is 20-30℃; the time of the second reaction is 18-30 h; and stirring is carried out during the second reaction.

[0013] Preferably, the concentration of iron ions in the iron-containing ethanol solution is 0.025-0.1M; the mass-to-volume ratio of the imine COF material to the iron-containing ethanol solution is 16-24 mg: 0.5-1.0 mL.

[0014] Preferably, the ultrasonic time in step 2) is 20-40 min; the stirring temperature is 20-30℃; and the stirring time is 2-5 h.

[0015] The present invention also provides a nanocomposite prepared by the above preparation method, using carbon oxide nanotubes as a carrier, wherein an imine covalent organic framework is grown on the surface of the carbon oxide nanotubes, and iron ions are incorporated into the imine covalent organic framework.

[0016] The present invention also provides a method for preparing a multifunctional antibacterial hydrogel, comprising the following steps: mixing an oxidized dextran solution sequentially with the nanocomposite, mixing a caffeic acid-grafted chitosan solution, and allowing it to stand to form a gel to obtain a multifunctional antibacterial hydrogel.

[0017] Preferably, the concentration of the oxidized dextran solution is 30-50 mg / mL, and the concentration of the caffeic acid-grafted chitosan solution is 10-30 mg / mL;

[0018] The concentration of the nanocomposite in the multifunctional antibacterial hydrogel is 0.25-2 mg / mL.

[0019] The present invention also provides a multifunctional antibacterial hydrogel prepared by the preparation method described above.

[0020] The present invention also provides the application of the nanocomposite or the multifunctional antibacterial hydrogel described herein in the preparation of drugs for antibacterial infection.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The nanocomposite prepared by this invention possesses photodynamic properties that are responsive to both acid and visible light, and can generate reactive oxygen species including hydroxyl radicals, superoxide anion radicals, and singlet oxygen radicals; it can be heated under 808nm laser irradiation; and it also has pH-responsive peroxidase (POD) and catalase (CAT) activities. It integrates multiple activities and can be used for the synergistic killing of bacteria in infected wounds and the regulation and repair of the wound microenvironment.

[0023] The multifunctional antibacterial hydrogel prepared by this invention possesses synergistic antibacterial activity of CDT / PTT / PDT, and exhibits injectability, self-healing, self-adaptation, adhesion, hemostasis, absorption of tissue exudate, and acid-responsive degradation properties. It can firmly cover wounds, release nanocomplexes in acidic infected tissue, catalyze the generation of ·OH from high levels of H2O2 in the infected wound microenvironment, and generate heat and a large amount of ROS under dual light source irradiation at 530nm and 808nm, achieving highly efficient synergistic antibacterial activity. Furthermore, it can self-oxygenate, alleviating long-term hypoxia at the wound site, enhancing intercellular conductivity, and promoting cell proliferation, thereby promoting angiogenesis and wound healing.

[0024] The multifunctional antibacterial hydrogel prepared by this invention can effectively resist MRSA infection, reduce inflammatory response, promote cell proliferation and angiogenesis, and ultimately accelerate the healing of MRSA-infected diabetic wounds. Attached Figure Description

[0025] Figure 1This is a flowchart illustrating the preparation process and therapeutic mechanism of the nanocomposite and multifunctional antibacterial hydrogel of this invention.

[0026] Figure 2 The images show the structural detection results of the imine COF material (O@C) and nanocomposite (O@CF) prepared in Example 1 (where a is the TEM image of OCNT; b and c are TEM images of O@CF at different magnifications; d is the STEM image of O@CF and its corresponding EDS elemental distribution image; e is a schematic diagram of the preparation of O@CF; f and h are the XRD patterns, FTIR patterns, nitrogen adsorption-desorption isotherms, and pore size distribution curves of OCNT, O@C, and O@CF, respectively (inset); i is the XPS image of OCNT, O@C, and O@CF; and j is the high-resolution Fe 2p XPS image).

[0027] Figure 3 The graph shows the performance test results of the imine COF material (O@C) and nanocomposite (O@CF) prepared in Example 1 (where a is at 808 nm (1.5 W·cm). -2 a) Photothermal images of OCNT, O@C, and O@CF solutions at the same OCNT concentration under different time periods of irradiation; b) UV-Vis spectra and corresponding photographs of different materials' POD enzyme activity detected by TMB display reaction (inset); c) Absorbance and EPR spectra of O@CF produced by ·OH detected by TMB display reaction at different pH buffers (inset), ·OH free radicals are captured by DMPO; d) Different materials at different pH... 7.4 The dissolved O2 content curve after incubation with H2O2 solution under the condition; e is the change of dissolved O2 content of O@CF after incubation with H2O2 solution in different pH buffers for 10 minutes; f is the absorbance caused by the generation of reactive oxygen species in COF, O@C or O@CF after irradiation with monochromatic light of different wavelengths for 15 minutes by colorimetric reaction with TMB solution; g is the absorbance caused by the generation of reactive oxygen species in different materials after irradiation with 500nm monochromatic light for 15 minutes at different pH values ​​by colorimetric reaction with TMB solution and photograph (insert); h is the absorbance at 352nm caused by H2O2 production in different materials after irradiation with 500nm monochromatic light for 15 minutes at different pH values ​​by KI-(NH4)MoO4 solution; i is the UV-Vis absorption caused by H2O2 production in different materials after irradiation with 500nm monochromatic light for 15 minutes at pH 6.0 by KI-(NH4)MoO4 solution.

[0028] Figure 4Figures show the structure and performance of the multifunctional antibacterial hydrogel (O@CF@G) prepared in Example 1. (a is an optical image of the O@CF@G hydrogel formation process; b is a SEM image of the O@CF@G hydrogel network, with orange circles representing O@CF nanotubes; c is the O@CF@G hydrogel strain scan curve; d is the oscillation time scan curve of the uncut O@CF@G hydrogel and the self-healing hydrogel after cutting; e is a photograph of the injectable O@CF@G hydrogel through a 22G needle; f is a photograph of the self-healing process of two semi-circular hydrogels, Gel and O@CF@G, after 15 minutes of contact; g is a photograph of O@CF@G adhering to pigskin under bending, warping, washing, and air-blowing conditions; h is a photograph of the downward penetration adaptive process of Gel and O@CF@G driven by gravity; ij is a photograph of the hydrogel formation process in the presence of blood cells and a comparison of the blood absorption capacity between the gel and O@CF@G; k is a photograph of Gel and O@CF@G under 808nm irradiation for different time periods (1.5W·cm).) -2 The image shows the photothermal properties of the O@CF@G hydrogel; 1 represents the conductivity of the O@CF@G hydrogel at different O@CF concentrations; mn represents the conductivity of the hydrogel after incubation with H2O2 (m) or under 500nm monochromatic light (100mW·cm). -2 Irradiation (n) for 15 minutes was performed, and the UV-Vis spectrum caused by ROS generation at pH 6.0 was detected by colorimetric projection using TMB solution; o represents the dissolved O2 content of different materials incubated with H2O2 (pH 6.0) for different times, and the data are expressed as Mean ± SD (n = 3).

[0029] Figure 5 This is a graph showing the detection results of the antibacterial, biofilm disruption, cytotoxicity, and hypoxia relief capabilities of the nanocomposite (O@CF) and multifunctional antibacterial hydrogel (O@CF@G) prepared in Example 1. (Where, ab are agar plate images and corresponding inhibition rates of different materials after incubation at 37°C for 2 hours against *Escherichia coli*, *Staphylococcus aureus*, and MRSA; c is SEM images of *Escherichia coli*, *Staphylococcus aureus*, and MRSA after incubation with different materials for 2 hours, with arrows indicating ruptured membranes and cytoplasmic leakage; de ​​shows the results of O@CF@G incubation of MRSA and MRS bacteria under different treatments.) A. Live and dead staining CLSM images of biofilm, where "c-" indicates the control group without any material (bright field: BF, green: Live, red: Dead); f. CLSM images of L929 cells incubated with different materials for intracellular O2 generation test (blue: DAPI, red: O2 probe [Ru(dpp)sCl]); g. L929 cell viability histogram on day 3 after different treatments; h. Live and dead staining images of L929 cells on days 1 and 3 after different treatments (green: live, red: dead). Data are expressed as Mean ± SD (n = 3).

[0030] Figure 6 This is an image showing the results of the anti-MRSA infection detection of the nanocomposite (O@CF) and multifunctional antibacterial hydrogel (O@CF@G) prepared in Example 1 (where ab is a wound photograph and relative wound area; c is a Gram staining image of wound tissue on day 6 after treatment, where black panes and circles mark Staphylococcus aureus stained purple, and black arrows indicate cells stained dark brown with high positivity; de is a Ki67 immunohistochemical staining image and corresponding Ki67 immunohistochemical analysis statistical graph; fg are wound tissue images on days 6 and 12 after treatment, respectively). H&E staining and Masson staining images are shown. In f, the black arrows represent inflammatory neutrophils, and in g, the red arrows, green panes, and black lines represent collagen deposition, hair follicles, and epidermal thickness, respectively. hk represents the ELISA quantitative results of CD31(h), TNF-α(i), IL-6(j), and IL-1β(k) in the wound tissue on days 6 and 12 after treatment. Data are expressed as mean ± SD (n = 3). *P < 0.05, **P < 0.01, ***P < 0.001. Detailed Implementation

[0031] This invention provides a method for preparing a nanocomposite, comprising the following steps:

[0032] 1) Carbon oxide nanotubes and 1,3,5-tris(4-aminophenyl)benzene were mixed to carry out the first reaction, and then mixed with 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and acetic acid solution to carry out the second reaction. After the second reaction was completed, the precipitate was collected, and the precipitate was washed and dried to obtain imine COF material.

[0033] 2) The imine COF material and an ethanol solution containing iron ions are mixed, ultrasonicated and stirred, the precipitate is collected, and the precipitate is washed and dried to obtain the nanocomposite.

[0034] In this invention, carbon oxide nanotubes are mixed with 1,3,5-tris(4-aminophenyl)benzene for a first reaction, and then mixed with a solution of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and acetic acid for a second reaction. After the second reaction, the precipitate is collected, washed, and dried to obtain the imine COF material. The carbon oxide nanotubes are preferably provided in the form of a carbon oxide nanotube-ethanol mixture. The concentration of carbon oxide nanotubes in the carbon oxide nanotube-ethanol mixture is preferably 0.5-1.5 mg / mL, more preferably 0.8-1.2 mg / mL. g / mL; In this invention, the 1,3,5-tris(4-aminophenyl)benzene is preferably dissolved in anhydrous acetonitrile; the mass-to-volume ratio of the 1,3,5-tris(4-aminophenyl)benzene to anhydrous acetonitrile is preferably 6-10 mg: 5-15 mL, more preferably 7-9 mg: 8-12 mL; In this invention, the mass ratio of the carbon nanotubes to 1,3,5-tris(4-aminophenyl)benzene is preferably 0.1-0.6 mg: 0.6-1.0 mg, more preferably 0.2-0.5 mg: 0.7-0.9 mg. In this invention, the temperature of the first reaction is preferably 20-30℃, more preferably 22-28℃; the reaction time is preferably 40-80 min, more preferably 50-70 min; the 2,5-dimethoxybenzene-1,4-dicarboxaldehyde is dissolved in acetonitrile solution, and the concentration of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde in the acetonitrile solution is preferably 6-10 mg / mL, more preferably 7-9 mg / mL; the carbon oxide... The preferred mass-to-volume ratio of nanotubes, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and acetic acid solution is 0.1-0.6 mg: 0.8-1.2 mg: 400-600 μL, more preferably 0.2-0.5 mg: 0.9-1.1 mg: 450-550 μL; the preferred temperature of the second reaction is 20-30 °C, more preferably 22-28 °C; the preferred reaction time is 18-30 h, more preferably 20-28 h; and the second reaction is accompanied by stirring. After the second reaction is completed, the precipitate is collected. Preferred method for collecting the precipitate is centrifugation. The centrifugation speed is preferably 6000-12000 rpm, more preferably 8000-10000 rpm. The centrifugation time is preferably 5-12 min, more preferably 8-10 min. The washing method is preferably alcohol washing, and the number of washing cycles is preferably 1-5 times, more preferably 2-4 times. The drying method is preferably vacuum drying. This invention does not have specific limitations on the vacuum drying parameters; conventional vacuum drying parameters in the art can be used.

[0035] In this invention, after obtaining the imine COF material, the imine COF material is mixed with an ethanol solution containing iron ions, ultrasonicated, stirred, and the precipitate is collected. The precipitate is then washed and dried to obtain a nanocomposite. The concentration of iron ions in the ethanol solution containing iron ions is preferably 0.025-0.1M, more preferably 0.03-0.09M; the mass-to-volume ratio of the imine COF material to the ethanol solution containing iron ions is preferably 16-24 mg : 0.5-1.0 mL, more preferably 18-22 mg : 0.6-0.9 mL; the ethanol solution containing iron ions is preferably an ethanol solution of FeCl3; the ultrasonication time is preferably 20-40 min, more preferably 25-35 min; the stirring temperature is preferably 20-30℃, more preferably 2℃. The temperature is 2-28℃; the stirring time is preferably 2-5 hours, more preferably 2.5-4.5 hours; the precipitate is preferably collected by centrifugation; the centrifugation speed is preferably 6000-12000 rpm, more preferably 8000-10000 rpm; the centrifugation time is preferably 3-10 minutes, more preferably 4-6 minutes; the washing method is preferably alcohol washing, preferably alcohol washing until the supernatant is colorless; the drying method is preferably freeze drying. The present invention does not have special limitations on the freeze drying parameters, and conventional freeze drying parameters in the art can be used.

[0036] The present invention also provides a nanocomposite prepared by the above preparation method, using carbon oxide nanotubes as a carrier, wherein an imine covalent organic framework is grown on the surface of the carbon oxide nanotubes, and iron ions are incorporated into the imine covalent organic framework.

[0037] The present invention also provides a method for preparing a multifunctional antibacterial hydrogel, comprising the following steps: mixing an oxidized dextran solution sequentially with the nanocomposite, mixing a caffeic acid-grafted chitosan solution, and allowing it to stand to form a gel to obtain a multifunctional antibacterial hydrogel.

[0038] In this invention, the method for preparing oxidized dextran in the oxidized dextran solution is as follows: after dissolving dextran in water, it is reacted with sodium periodate, and then ethylene glycol is added, mixed and stirred, dialyzed, and dried to obtain oxidized dextran. The preferred mass-to-volume ratio of dextran to water is 2-6 g: 40-60 mL, more preferably 3-5 g: 45-55 mL; the preferred mass-to-volume ratio of dextran, sodium periodate, and ethylene glycol is 2-6 g: 0.5-2 g: 800-1000 μL, more preferably 3-5 g: 0.8-1.5 g: 850-950 μL; the preferred reaction temperature is 20-30℃, more preferably 22-28℃; the preferred reaction time is 18-30 h, more preferably 20-28 h; the preferred stirring temperature is 20-30℃, more preferably 22-28℃; the preferred stirring time is 40-80 min, more preferably 50-70 min; dialysis is performed using a dialysis bag, the preferred molecular weight cutoff of which is 8-15 kDa, more preferably 9-14 kDa; the preferred dialysis time is 2-5 days, more preferably 3-4 days; the drying method is freeze-drying.

[0039] In this invention, the preparation method of caffeic acid-grafted chitosan in the caffeic acid-grafted chitosan solution is as follows: caffeic acid and dimethyl sulfoxide are mixed and dissolved to obtain solution A; 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, N-hydroxysuccinimide ester and dimethyl sulfoxide are mixed and dissolved to obtain solution B; dimethyl sulfoxide and water are mixed to obtain a mixed solution; chitosan and the mixed solution are mixed and dissolved, and the pH is adjusted with hydrochloric acid to obtain a reaction solution; solution A is first added to the reaction solution and stirred for the first time, then solution B is added and stirred for the second time, dialyzed, and dried to obtain caffeic acid-grafted chitosan. The preferred mass-to-volume ratio of caffeic acid to dimethyl sulfoxide is 350-380 mg: 8-12 mL, more preferably 355-375 mg: 9-11 mL; the preferred mass-to-volume ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, N-hydroxysuccinimide ester, and dimethyl sulfoxide is 750-780 mg: 440-480 mg: 8-12 mL, more preferably 755-775 mg: 450-470 mg: 9-11 mL; the preferred mass-to-volume ratio of dimethyl sulfoxide, water, and chitosan is 3-7 mL: 0.5-2 g: 1-3 mL, more preferably 4-6 mL: 0.8-1.5 g: 1.5-2.5 mL. The concentration of the hydrochloric acid solution is preferably 0.5-1.5M, more preferably 0.8-1.2M; the pH of the reaction solution is preferably 4-5, more preferably 4.2-4.8; the temperature of the first stirring is preferably 20-30℃, more preferably 22-28℃; the time of the first stirring is preferably 20-40min, more preferably 25-35min; the temperature of the second stirring is preferably 20-30℃, more preferably 22-28℃; the time of the second stirring is preferably 18-30h, more preferably 20-28h; the dialysis time is preferably 2-5 days, more preferably 3-4 days; the drying method is freeze-drying.

[0040] In this invention, the preparation method of the oxidized dextran solution is as follows: weigh 60-100 mg of oxidized dextran into a beaker, add 2 mL of PBS solution and a magnetic stir bar of appropriate size, and stir to obtain a clear oxidized dextran solution; the concentration of the oxidized dextran solution is preferably 30-50 mg / mL, more preferably 35-45 mg / mL; the preparation method of the caffeic acid-grafted chitosan solution is as follows: weigh 20-60 mg of caffeic acid-grafted chitosan into a beaker, add 2 mL of PBS solution and a magnetic stir bar of appropriate size, and stir to obtain a clear caffeic acid-grafted chitosan solution; the concentration of the caffeic acid-grafted chitosan solution is preferably 10-30 mg / mL, more preferably 15-25 mg / mL; the multifunctional The concentration of the nanocomposite in the antibacterial hydrogel is preferably 0.25-2 mg / mL, more preferably 0.3-1.8 mg / mL; the mixing ratio of the oxidized dextran solution, the nanocomposite, and the caffeic acid-grafted chitosan solution is preferably 0.5-2 mL: 0.5-4 mg: 0.5-2 mL, more preferably 0.8-1.5 mL: 1-3 mg: 0.8-1.5 mL; the mixing is preferably carried out using a vortex mixer, preferably until uniform dispersion; the mixing time is preferably 30-120 s, more preferably 40-60 s; the standing temperature is preferably 20-30℃, more preferably 22-28℃; the standing time is preferably 1-10 min, more preferably 4-6 min.

[0041] The present invention also provides a multifunctional antibacterial hydrogel prepared by the preparation method described above.

[0042] The present invention also provides the application of the nanocomposite or the multifunctional antibacterial hydrogel described herein in the preparation of drugs for antibacterial infection.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] The preparation method of the nanocomposite is as follows:

[0046] 10 mg of 1,3,5-tris(4-aminophenyl)benzene (TAPB) was dissolved in 10 mL of anhydrous acetonitrile. Then, 5 mL of an ethanol mixture of carbon oxide nanotubes (OCNT) (1 mg / mL) was added to this solution. After reacting at room temperature for 1 h, 8 mg / mL of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) acetonitrile solution and 500 μL of acetic acid were added. The mixture was stirred at room temperature for another 24 h. After the reaction was complete, the reaction solution was centrifuged (9000 rpm, 9 min) to collect the precipitate, washed three times with alcohol, and vacuum dried to obtain the imine COF material (O@C). 20 mg of the obtained imine COF material (O@C) was impregnated in 800 μL of 0.05 M FeCl3 ethanol solution, sonicated for 30 min, stirred at room temperature for 4 h, then centrifuged (9000 rpm, 5 min) and washed with alcohol until the supernatant was colorless. Finally, the nanocomposite (O@CF) was obtained by freeze-drying.

[0047] The preparation method of the multifunctional antibacterial hydrogel is as follows:

[0048] Preparation of oxidized dextran (ODex): Weigh 4g of dextran and dissolve it in 50mL of deionized water. After complete dissolution, add 1g of sodium periodate to the reaction solution and stir in the dark at room temperature for 24h. After the reaction is complete, add 900μL of ethylene glycol as a quencher and continue stirring in the dark for 1h. Then, transfer the entire solution to a dialysis bag with a molecular weight cutoff of 12kDa and dialyze it in deionized water for 3 days. After dialysis, freeze-dry to obtain ODex.

[0049] Preparation of caffeic acid-grafted chitosan (CACS): A solution of deionized water and dimethyl sulfoxide in a 5:2 ratio was prepared in advance. 1 g of chitosan was weighed and dispersed in the prepared solution. 1 M hydrochloric acid was slowly added to adjust the pH until the chitosan was completely dissolved, resulting in a clear solution. 360 mg of caffeic acid was weighed and dissolved in 10 mL of dimethyl sulfoxide (DMSO). This solution was slowly added dropwise to the above reaction solution and stirred at room temperature for 30 min. Then, 766 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 460 mg of N-hydroxysuccinimide ester were weighed and dissolved in 10 mL of DMSO. This solution was also slowly added dropwise to the reaction solution. The pH of the reaction solution was adjusted to 4.5, and then stirred at room temperature for 24 h. After the reaction was completed, the solution was dialyzed for 3 days and then freeze-dried to obtain a pale yellow spongy CACS.

[0050] 80 mg of oxidized dextran was placed in a beaker, 2 mL of PBS solution and a magnetic stir bar of appropriate size were added. After stirring, a clear 40 mg / mL oxidized dextran solution was obtained. 40 mg of caffeic acid grafted chitosan was placed in a beaker, 2 mL of PBS solution and a magnetic stir bar of appropriate size were added. After stirring, a clear 20 mg / mL caffeic acid grafted chitosan solution was obtained. Then, a certain mass of O@CF nanocomposite was mixed with 1 mL of ODex solution, and then 1 mL of CACS solution was added. The mixture was evenly dispersed on a vortex mixer and left to gel at room temperature. The concentrations of O@CF in the hydrogel were 0, 0.25, 0.5, 1.0, and 2.0 mg / mL, respectively.

[0051] Experimental Example 1

[0052] The imine COF material (O@C) and nanocomposite (O@CF) prepared in Example 1 were subjected to structural detection:

[0053] Morphology characterization of the materials: The morphology and microstructure of the materials were characterized using a field emission transmission electron microscope (TEM) and a scanning electron microscope (SEM). Before testing, a small amount of the sample to be measured was evenly dispersed in ethanol. 20 μL of the dispersion was dropped onto a clean tin foil paper, air-dried, and then fixed on an SEM sample stage with conductive glue for SEM testing; the dispersion was dropped on a copper grid and air-dried naturally for TEM testing. The energy dispersive spectrometer (EDS) equipped with the TEM was used to qualitatively analyze the elemental species, distribution, and content in the microregions of the materials.

[0054] The morphology of O@C was analyzed, as shown in a-b of Figure 2 where OCNT is a one-dimensional tubular structure;

[0055] As shown in c of Figure 2 in O@CF, the prepared O@CF is a uniform nanotube with a diameter of about 70 nm, where the OCNT diameter is 11 nm and the outer COF layer thickness is 30 nm.

[0056] As shown in d of Figure 2 it was confirmed by TEM-mapping elemental analysis that C, N, O, and Fe elements are uniformly distributed in the O@CF nanotube.

[0057] Therefore, we推测 the synthesis route of O@CF is as shown in e of Figure 2 where.

[0058] Structural characterization of the materials: Fourier transform infrared spectroscopy (FT-IR) was used to analyze the types and structures of chemical groups in the materials; X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition of the sample surface and its chemical states and bonding types at the atomic level; palladium X-ray diffraction (XRD) was used to analyze the phase and crystal structure of the samples, with a 2θ range of 2–90°; and a fully automated surface area and porosity analyzer (BET) was used to analyze the porous structure of the samples, with nitrogen as the adsorbed gas, and the pore size distribution was determined by nonlocal density functional theory (NLDFT).

[0059] Depend on Figure 2 The XRD results for f show that OCNT, O@C, and O@CF all exhibit a (002) diffraction peak at 2θ = 25.8°, at which they belong to CNT. Furthermore, in composites with OCNT and with Fe loading... 3+ Afterwards, the diffraction peaks belonging to the COF(100) plane still exist.

[0060] like Figure 2 As shown in g, a 1620 cm⁻¹ was observed in the infrared spectra of both O@C and O@CF. -1 The tensile vibration peaks of C=N nearby confirm the formation of the imine covalent bond COF. Simultaneously, the characteristic peaks of O@CF are observed to be essentially the same as those of O@C, indicating that Fe... 3+ Coordination did not destroy its bonding structure.

[0061] Figure 2 In the figure, h represents the N2 adsorption-desorption curves of OCNT, O@C, and O@CF. OCNT exhibits a type II isotherm, indicating that OCNT has a macroporous structure; while O@C and O@CF exhibit typical type IV isotherms, indicating that O@C and O@CF have microporous-mesoporous structures. Figure 2 The pore size distribution results in the h-plot also prove their hierarchical pore structure.

[0062] XPS was used to analyze the elements and their bond types in OCNT, O@C, and O@CF, such as... Figure 2 As shown in Figure i, the XPS spectrum of O@CF shows an Fe 2p peak, indicating successful Fe loading. Furthermore... Figure 2 The high-resolution Fe 2p spectrum at 711.7 eV, 725.4 eV, and 717.8 eV respectively shows the Fe 2p region. 3+ The Fe 2p3 / 2, Fe 2p1 / 2, and Fe 2p3 / 2 peaks indicate that Fe is present in O@CF as Fe2p3 / 2. 3+ The ionic state exists. These results indicate that Fe exists in O@CF. 3+ Successfully loaded into the channels of COF.

[0063] Experiment Example 2

[0064] The photothermal conversion performance, H2O2 catalytic activity for forming ·OH, H2O2 catalytic activity for forming O2, photoactive oxygen performance, and H2O2 generation performance of the imine COF material (O@C) and nanocomposite (O@CF) in Example 1 were measured:

[0065] To test the photothermal conversion performance of the samples, the OCNT, imine COF material (O@C), and nanocomposite (O@CF) from Example 1 were uniformly dispersed in PBS. 200 μL of the dispersion was taken and irradiated with an 808 nm near-infrared laser for 10 min. The thermal image of the dispersion was recorded in real time using an infrared thermal imager.

[0066] Experimental results: such as Figure 3 As shown in 'a'. From Figure 3 From 'a' in the equation, we can see that under 808nm laser irradiation (1.5W·cm⁻¹), -2 At this temperature, a 0.125 mg / mL LO@CF solution can still be heated to 54.8 °C after 10 minutes.

[0067] The activity of OCNT, imine COF material (O@C), and nanocomposite (O@CF) in Example 1 in catalyzing the formation of ·OH from H2O2 was determined by TMB detection. OCNT, imine COF material (O@C), and nanocomposite (O@CF) from Example 1 were added to 1 mL of NaAc-Hac buffer solution containing 0.5 mM TMB and 1 mM H2O2 (pH 5.0, 6.0, and 7.4, respectively). The solution was placed in a shaker at 37°C and 150 rpm in the dark for 20 min, and then centrifuged. The absorbance at 652 nm was measured. Furthermore, in the above reaction solutions at pH 5.0 and 7.4, the TMB indicator was replaced with a DMPO scavenger, and after reacting in the dark for 20 min, the signal of DMPO-·OH was detected by EPR.

[0068] Experimental results: such as Figure 3 As shown in b and c in the diagram. (By...) Figure 3 As can be seen from b and c, O@CF possesses POD enzyme activity, which is enhanced under acidic conditions.

[0069] To test whether the OCNT, imine COF material (O@C), and nanocomposite (O@CF) in Example 1 possess the activity to catalyze the formation of O2 from H2O2, 30% (v / v) H2O2 aqueous solutions were prepared by diluting them with PBS buffer solutions at pH values ​​of 5.0, 6.0, and 7.4, resulting in 100 mM H2O2 aqueous solutions with different pH values. Then, 2 mL of each of the OCNT, imine COF material (O@C), and nanocomposite (O@CF) from Example 1 was added, and the change in dissolved oxygen content was monitored in real time over 10 minutes using a portable dissolved oxygen meter.

[0070] Experimental results: such as Figure 3 As shown by d and e in the diagram. Figure 3 As can be seen from d and e, O@CF possesses CAT enzyme activity, which is enhanced under alkaline conditions.

[0071] The photoactive oxygen properties of pure COF material, the imine COF material (O@C) prepared in Example 1, and the nanocomposite (O@CF) were determined by the TMB colorimetric method. Samples were added to 1 mL of NaAc-HAc buffer solution (pH 5.0, 6.0, and 7.4) containing 0.5 mM 3,5,3,5-tetramethylbenzidine (TMB), and then subjected to a 100 mW·cm⁻¹ solution. -2 After irradiation with 500 nm monochromatic light at a power density for 15 min, the supernatant was centrifuged and the absorbance at 652 nm was measured using a UV-Vis spectrophotometer.

[0072] Experimental results: such as Figure 3 As shown by f and g in the figure. Figure 3 As can be seen from f and g, O@CF photodynamic ROS generation is significantly enhanced, and it can still generate a certain amount of ROS even under long-wavelength light irradiation of 700nm, which is far superior to pure COF.

[0073] The formation of H₂O₂ was detected by iodometric titration. H₂O₂ oxidizes I⁻ to I⁻³ in the presence of ammonium molybdate catalyst, exhibiting enhanced absorbance at 352 nm. 1 mL of 2 M KI and 50 μL of 10 mM ammonium molybdate were added to 1 mL of COF, O@C, and O@CF solutions of different concentrations. After irradiation for 15 min, the absorption spectra were measured using a UV-Vis spectrophotometer.

[0074] Experimental results: such as Figure 3 As shown by h and i in the diagram. Figure 3 As can be seen from h and i, O@CF has the ability to generate H2O2.

[0075] Experimental Example 3

[0076] The multifunctional antibacterial hydrogels (O@CF@G) prepared in Example 1 with concentrations of 0, 0.25, 0.5, 1.0, and 2.0 mg / mL were used, and the gelation time was recorded by inverting the tubes. The multifunctional antibacterial hydrogels were labeled O@CF@G, while the pure hydrogel without O@CF was labeled Gel, and their structure and properties were determined.

[0077] The gelation time was determined by the tube inversion method, which refers to the time it takes for the hydrogel formed by the mixture of components to remain unflowed when inverted in a vial. Oxygenated dextran solution, nanocomposite, and caffeic acid-grafted chitosan solution were mixed in a ratio of 1:0.2:2, and the tube inversion experiment was performed. The gelation time of the O@CF@G gel sample was recorded.

[0078] Figure 4 In the figure, 'a' represents the preparation method of O@CF@G hydrogel. The ODex solution containing O@CF nanotubes is mixed with CACS solution to form a hydrogel. The gelation time of O@CF@G is measured to be 36s by the tube inversion method.

[0079] The morphology of Gel and O@CF@G was observed by SEM. The specific procedure was as follows: the freeze-dried hydrogel sample was quenched in liquid nitrogen, and the exposed cross section was fixed on the sample stage with gold sputtering before observation.

[0080] like Figure 4 As shown in b, the gel retains its three-dimensional network structure after being doped with O@CF nanotubes, and the loading of O@CF can be observed on its gel surface. In particular, the fracture surface exposes the suspended O@CF nanotubes, which means that some O@CF is entangled with the polymer and thus interspersed in the three-dimensional network structure.

[0081] The rheological properties of the hydrogels were obtained using a rheometer. Testing was conducted 30 min after gelation of O@CF@G and gel using a 20 mm flat plate mold. The oscillation time-scan test conditions were: temperature 25℃, strain 1%, frequency 1 Hz. The strain scan test conditions were: temperature 25℃, frequency 1 Hz, with strain logarithmically varying between 0.01% and 1500%.

[0082] Figure 4 In the figure, c represents the strain scan curve of O@CF@G. The fracture strain of O@CF@G is 653%, which indicates that O@CF@G has a certain degree of toughness, thus distributing some of the mechanical energy when the hydrogel is subjected to external force, reducing the possibility of fracture.

[0083] like Figure 4 As shown in d, the storage modulus and loss modulus of O@CF@G only changed slightly during the test time, indicating that the three-dimensional network structure formed by the hydrogel through the Schiff base reaction is stable.

[0084] Injectability, self-healing, adaptive, and adhesive behavior characterization: The injectability of the hydrogel was assessed by loading it into a syringe with a 22G needle and observing its ability to be smoothly ejected from the needle. Furthermore, the self-healing behavior was evaluated by stretching the hydrogel after it had been cut and separated and left in contact for a certain period. The adaptive behavior of the hydrogel was assessed by placing it in a test tube containing numerous small spheres (3 mm in diameter) and observing the hydrogel's seepage at different time points. Pigskin was used as a substitute for human skin tissue. The hydrogel was placed upside down on a clean pigskin surface and pressed with a smooth metal object for 2 minutes. Then, the pigskin was subjected to bending, twisting, stretching, water rinsing, and airflow agitation to observe the hydrogel's adhesive behavior.

[0085] like Figure 4 As shown in the figure, O@CF@G can be injected with a syringe to produce different letter shapes.

[0086] like Figure 4 As shown in f, O@CF@G was brought into contact with the cross-section of the gel. After 15 minutes, the hydrogel was stretched and it was observed that the cross-sections of the gel and O@CF@G had adhered together.

[0087] in addition, Figure 4 After placing O@CF@G on pigskin and pressing for 2 minutes, it remained firmly fixed to the pigskin surface even after being stretched, bent, twisted, rinsed with water, and impacted by airflow.

[0088] and Figure 4 The 'h' in the figure shows the adaptive behavior of Gel and O@CF@G. After 30 minutes, O@CF@G was able to cover the surface and begin to penetrate into the vacancies. After 2 hours, it reached the bottom of the centrifuge tube. At this point, Gel had just penetrated the surface. This is because the hydrogel is gelled by dynamic Schiff base bonds. Due to the obstruction of O@CF nanotubes, O@CF@G is not fully cross-linked inside after gelation and has a certain degree of softness. Therefore, under the action of gravity, it will fill the vacancies downward.

[0089] The in vitro hemostatic properties of the O@CF@G hydrogel were also evaluated. Figure 4 The data shows that Gel and O@CF@G still gel in the presence of blood cells, indicating that the hydrogel can encapsulate blood and prevent leakage. In addition, Figure 4 The results showed that when blood was dropped onto the surface of the gel and O@CF@G gel, it was completely absorbed after 6 hours, which means that the hydrogel can also absorb blood to deal with wound bleeding.

[0090] Because hydrogels are relatively soft and cannot be fixed in shape, a cylindrical mold with a diameter of 6 mm and a thickness of 0.1 mm was used to measure the conductivity of the hydrogel. The mold was filled with hydrogel, and copper sheets were placed at both ends and clamped with battery clips. It was then connected to an electrochemical station, and the resistance (R) was measured by electrochemical impedance spectroscopy. The CAT activity, POD activity, photothermal properties, and photodynamic properties of the O@CF functionalized hydrogel were characterized as they were for O@CF particles.

[0091] like Figure 4 As shown in k, O@CF@G exhibits excellent photothermal properties, increasing by 41.2℃ after 10 min of near-infrared light irradiation with 1.5W cm-2 power, while pure gel only increased by 3.2℃.

[0092] like Figure 4 As shown in Figure 1, the conductivity of the hydrogel gradually increases with the increase of O@CF incorporation. Meanwhile, the conductivity of both pure gel and O@CF@G remains within the conductivity range of skin tissue (1×10⁻⁵ S m). -1 ~0.26S m -1 The conductivity of pure gel is 0.03 S m. -1 The O@CF content is 1.0 mg / mL. -1 The conductivity of O@CF@G is 0.12 S m. -1 .

[0093] like Figure 4 As shown in m, O@CF@G can generate ROS under 500nm illumination.

[0094] like Figure 4 As shown in figure no, O@CF@G can generate ROS under 500nm illumination, but exhibits weakened photodynamic properties compared to dispersed O@CF. This is because O@CF, after being encapsulated in hydrogel, cannot be dispersed in the reaction solution, thus reducing its contact with the substrates H2O and O2.

[0095] Experiment Example 4

[0096] Cultures of *E. coli*, *S. aureus*, and methicillin-resistant *S. aureus* (MRSA) were diluted 10⁵ times. 400 μL of the diluted solution was added to the following materials and grouped: PBS group, COF group, O@C group, O@CF group, O@CF@G group, and Gel group. Then, 40 μL of 1 mM H₂O₂ solution was added to the mixture and mixed thoroughly. The mixture was then irradiated with dual light sources at 530 nm and 808 nm for 10 min, and incubated at 37°C for 2 h in a shaker at 150 rpm. 200 μL of the mixture was spread onto nutrient agar plates, which were then inverted and incubated at 37°C for 16 h. The bacterial count was then observed. In addition, to investigate the antibacterial efficacy of CDT, PTT, and PDT, as well as the inherent antibacterial efficacy of gel itself, O@CF and O@CF@G were mixed with MRSA bacterial dilutions. After grouping and treatment with or without H2O2 addition, 530nm irradiation, and 808nm irradiation, the mixed solutions were plated and incubated at 37°C for 16 hours before the number of bacterial strains was observed.

[0097] MRSA bacterial culture was passaged for 12 h. Then, 100 μL of activated bacterial culture and 100 μL of sterile nutrient broth were added to 96-well plates and incubated at 37°C for 48 h. The supernatant was then aspirated, and the plates were gently rinsed twice with PBS. Finally, 100 μL of PBS buffer was added. The milky white membrane-like layer at the bottom of the wells was the bacterial biofilm and the bacteria within it. Different samples were added to the above wells and grouped as follows: COF group, O@C group, O@CF group, O@CF@G group, and Gel group. A Blank group without biofilm was set up as a negative control, and a Control group with PBS was set up as a positive control. Then, 100 μM H2O2 was added under static conditions, and the plates were irradiated with dual light sources at 530 nm and 808 nm for 15 min. After incubation for 4 h, the culture medium and samples were aspirated, and the plates were gently rinsed twice with PBS. The PBS was aspirated, and 50 μL of methanol was added to fix the biofilm for 30 min. After removing the methanol, crystal violet solution was added for staining. After 30 minutes, the dye was aspirated and gently rinsed three times with PBS, then inverted to air dry. Finally, 100 μL of 95% ethanol was added to the well plate to dissolve the crystal violet dye, and the absorbance of each solution at 590 nm was measured using a microplate reader to assess the sample's ability to disrupt biofilms.

[0098] 100 μL of L929 fibroblasts (2000 cells / well) were seeded in 96-well plates and incubated for 12 h. The medium was then replaced with 100 μL of fresh medium containing 10 μg mL⁻¹ of O@CF or O@CF@G. The plates were then incubated for a total of 72 h. The CCK-8 assay for cell viability and the calculation of cell survival rate were performed in the same manner as in the cytotoxicity assay.

[0099] Changes in intracellular O2 content were characterized using the O2 quenching probe {[Ru(dpp)3]Cl2}. L929 cells were seeded in 96-well plates and incubated for 12 hours in a hypoxic incubator until cell attachment. The culture medium was then replaced, and the L929 cells were incubated with different materials in a high-level H2O2 (100 μM) hypoxic (5% O2) environment for 24 hours. Then, 1 μL of [Ru(dpp)3]Cl2 (1 mg / mL) was added to each well, and incubation continued for another 12 hours. Finally, the culture medium was aspirated, and the cells were gently washed three times with PBS to remove free [Ru(dpp)3]Cl2. The hypoxia-alleviating ability of different materials was evaluated by observing the red fluorescence produced in each well at 450 nm excitation light using an inverted fluorescence microscope.

[0100] Experimental results: such as Figure 5 As shown. By Figure 5 The results show that O@CF and O@CF@G have an antibacterial efficiency of almost 100% against various bacteria. Figure 5 The image shows that the combined sterilization effect of O@CF@G's POD effect (+H2O2), photothermal heating (+808nm), and photodynamic treatment (+530nm) can even be achieved on refractory biofilms, almost eliminating all biofilms. Figure 5 f in the figure shows that due to Fe 3+ Coordination-induced CAT enzyme activity was alleviated by treatment with O@CF and O@CF@G (but not other corresponding treatments) to relieve hypoxia. Figure 5 The results showed that treatment with O@CF@G even helped increase cell proliferation.

[0101] Experimental Example 5

[0102] Male C57BL / 6 mice (over 8 weeks old, weighing approximately 20g) were used to model MRSA-infected diabetic wounds. After 12 hours of inoculation, MRSA infection was introduced. All animal experiments were conducted according to the guidelines approved by the Ethics Committee of Donghua University, and all experimental procedures complied with relevant national regulations and the "Guidelines on the Humane Treatment of Laboratory Animals." First, after fasting for 12 hours with free access to water, mice were intraperitoneally injected with 100 μL of a 10 mg / mL streptozotocin (STZ) solution, and this administration was repeated for one week. Blood glucose levels were monitored starting on day 5; a sustained blood glucose level greater than 16.7 mmol / L for one week indicated successful modeling. The successfully modeled mice were then anesthetized, and their dorsal hair was removed. An 8 mm circular wound was made on the back using a medical punch, and 20 μL of MRSA cultured for 12 hours was added to establish a diabetic MRSA-infected wound model. The day the diabetic wound infection model was established was designated as day 0. Mice were randomly divided into 6 groups of 3 mice each: Control group (100 μL PBS buffer solution), COF group, O@C group, O@CF group, O@CF@G group, and Gel group. After 12 hours of wound infection, a mixture of nanomaterials or hydrogel material was applied to the wound. Then, on days 1, 3, and 5, the wounds were irradiated with dual light sources at 530 nm and 808 nm for 10 minutes each. Wound photographs were taken on days 0, 3, 6, 9, and 12.

[0103] On the 6th day after wound treatment in mice, wound samples were taken for pathological sectioning. The corresponding slides were obtained by hematoxylin and eosin (H&E), Masson trichrome staining, rapid Gram staining, and Ki67 immunohistochemistry. The slide images were obtained by slide scanner.

[0104] On days 6 and 12 of treatment, tissue was taken from under the scab of the mouse wound. 100 mg of the tissue was weighed and mixed with 10 mL of PBS buffer solution and homogenized. The tissue homogenates from each experimental group were then centrifuged at 5000 rpm for 5 min. The supernatant was collected and the concentrations of CD31, IL-1β, IL-6 and TNF-α in the supernatant were determined using an ELISA kit.

[0105] Experimental results: such as Figure 6 As shown, by Figure 6 The results show that O@CF@G, and even O@CF powder, has a faster wound-closing speed than other materials. Figure 6 The figure 'c' shows that on day 6 post-treatment, O@CF and O@CF@G also had fewer residual bacteria in the wound tissue. Figure 6The data from the study showed that O@CF and O@CF@G treatments also resulted in higher Ki67 expression levels and corresponding positive expression rates, indicating that they promote cell proliferation.

[0106] Depend on Figure 6 The f-values ​​in the image show that the O@CF@G group experienced the fastest and greatest reduction in inflammatory cell infiltration (black arrows stained with H&E), with inflammation almost disappearing by day 6 post-treatment. Figure 6 The g-values ​​in the data show that the O@CF@G group has significant collagen deposition and epithelialization. Furthermore, the g-values ​​in the data indicate that the O@CF@G group exhibits substantial collagen deposition and epithelialization. Figure 6 The study, conducted using HK, demonstrated that quantitative analysis of pro-inflammatory factors (TNF-α, IL-6, IL-1β) and angiogenesis factor (CD31) in wound tissue confirmed a gradual reduction in inflammation and an increase in angiogenesis after treatment (adequate oxygen supply promotes angiogenesis), with O@CF@G showing the best performance. These results indicate that the multifunctional antibacterial hydrogel O@CF@G can effectively resist MRSA infection, reduce inflammatory response, promote cell proliferation and angiogenesis, and ultimately accelerate the healing of MRSA-infected diabetic wounds.

[0107] As can be seen from the above embodiments and experimental examples, the nanocomposite prepared by the present invention has photodynamic properties with dual responses to acid and visible light, and can be used for synergistic killing of bacteria in infected wounds and regulation and repair of the wound microenvironment; the multifunctional antibacterial hydrogel prepared by the present invention has CDT / PTT / PDT synergistic antibacterial activity, can provide its own oxygen to alleviate the long-term hypoxia problem at the wound site, enhance the conductivity between cells, promote cell proliferation, thereby promoting angiogenesis and wound healing.

[0108] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nanocomposite, characterized in that, Includes the following steps: 1) Carbon oxide nanotubes and 1,3,5-tris(4-aminophenyl)benzene were mixed to carry out the first reaction, and then mixed with 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and acetic acid solution to carry out the second reaction. After the second reaction was completed, the precipitate was collected, and the precipitate was washed and dried to obtain imine COF material. 2) The imine COF material and an ethanol solution containing iron ions are mixed, ultrasonicated and stirred, the precipitate is collected, and the precipitate is washed and dried to obtain the nanocomposite.

2. The method for preparing the nanocomposite according to claim 1, characterized in that, The mass ratio of the carbon nanotubes to 1,3,5-tris(4-aminophenyl)benzene is 0.1-0.6 mg : 0.6-1.0 mg; The mass-to-volume ratio of the carbon nanotubes, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and acetic acid solution is 0.1-0.6 mg: 0.8-1.2 mg: 400-600 μL.

3. The method for preparing the nanocomposite according to claim 1, characterized in that, In step 1), the temperature of the first reaction is 20-30℃; the time of the first reaction is 40-80 min; the temperature of the second reaction is 20-30℃; the time of the second reaction is 18-30 h; and stirring is carried out during the second reaction.

4. The method for preparing the nanocomposite according to claim 1, characterized in that, The concentration of iron ions in the iron-containing ethanol solution is 0.025-0.1 M; the mass-to-volume ratio of the imine COF material to the iron-containing ethanol solution is 16-24 mg: 0.5-1.0 mL.

5. The method for preparing the nanocomposite according to claim 1, characterized in that, The ultrasonic time in step 2) is 20-40 min; the stirring temperature is 20-30℃; and the stirring time is 2-5 h.

6. The nanocomposite obtained by the preparation method according to any one of claims 1 to 5, characterized in that, Using carbon oxide nanotubes as a carrier, an imine-based covalent organic framework is grown on the surface of the carbon oxide nanotubes, and iron ions are incorporated into the imine-based covalent organic framework.

7. A method for preparing a multifunctional antibacterial hydrogel, characterized in that, The process includes the following steps: mixing an oxidized dextran solution with the nanocomposite described in claim 6, adding a caffeic acid-grafted chitosan solution, and allowing it to stand to form a gel to obtain a multifunctional antibacterial hydrogel.

8. The method for preparing the multifunctional antibacterial hydrogel according to claim 7, characterized in that, The concentration of the oxidized dextran solution is 30-50 mg / mL, and the concentration of the caffeic acid-grafted chitosan solution is 10-30 mg / mL. The concentration of the nanocomposite in the multifunctional antibacterial hydrogel is 0.25-2 mg / mL.

9. The multifunctional antibacterial hydrogel prepared by the preparation method according to claim 7 or 8.

10. The use of the nanocomposite of claim 6 or the multifunctional antibacterial hydrogel of claim 9 in the preparation of a drug for treating bacterial infections.

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