PCN-coated Au / GOx-F68 / F127 antibacterial temperature-sensitive hydrogel as well as preparation method and application of PCN-coated Au / GOx-F68 / F127 antibacterial temperature-sensitive hydrogel

Abstract

The invention belongs to the technical field of photoresponse antibacterial dressings, and discloses PCN-coated Au / GOx-F68 / F127 antibacterial temperature-sensitive hydrogel and a preparation method and application thereof.The PCN-coated Au / GOx-F68 / F127 antibacterial temperature-sensitive hydrogel can complete conversion of gel and sol under the condition of 4-37 DEG C, PCN-coated Au nano-enzyme is constructed by means of an in-situ growth method, and after the PCN-coated Au nano-enzyme is integrated with GOx, a self-activated enzymatic cascade reaction is formed by means of the hydrogel. GOx decomposes glucose to generate H2O2 and gluconic acid, the pH of a wound is reduced, PCN-coated Au decomposes endogenous H2O2 under an acidic condition to generate ROS for sterilization, limitation of a high-blood-sugar and high-pH environment on catalytic activity is avoided, meanwhile, photodynamic synergistic antibiosis is achieved, the synthesis condition is mild, the process is simple, and economical and feasible effects are achieved. The hydrogel has thermosensitivity, can relieve wound pain, does not loosen after absorbing exudate, has no residue, and does not adhere to a wound surface when being removed. Under the irradiation of visible light, the methicillin-resistant staphylococcus aureus and the escherichia coli capable of producing extended-spectrum beta-lactamase can reach gt within 0-30 minutes; the clearance rate is 99.9%, and a new way is provided for developing novel medical dressings for treating diabetic bacterial infection wounds.

Description

[0001] The present invention belongs to the technical field of light-responsive antibacterial dressings, and specifically relates to a PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel and a preparation method and application thereof. Background Art

[0002] Diabetic wounds (such as diabetic foot ulcers) are often difficult to heal and are accompanied by serious infection risks due to microcirculatory disorders, immunosuppression and increased bacterial susceptibility caused by long-term hyperglycemia. Traditional antibiotic treatment faces the challenge of drug resistance. Light-responsive antibacterial technologies such as photodynamic antibacterial therapy (APDT) have become a research hotspot for anti-infection treatment due to their advantages such as non-invasiveness, spatiotemporal controllability and low resistance to drug induction. However, single photodynamic therapy still has limitations. For example, the diffusion range of reactive oxygen species (ROS) in APDT is limited, making it difficult to completely kill deep-seated bacteria. Therefore, the development of new synergistic antibacterial strategies, combining photodynamic sterilization with metabolic regulation, has become a research hotspot for the treatment of diabetic wounds.

[0003] Porphyrin MOFs are typical semiconductor-like photocatalytic materials with a broad absorption range. The porphyrin ring is a large conjugated system containing 18 π electrons, resulting in excellent light absorption and high energy transfer efficiency. This allows MOFs to achieve visible light and even near-infrared photocatalysis, increasing the number of photogenerated electron-hole pairs generated under sunlight. They are excellent platform materials for the construction of photosensitizers and nanozymes. However, pure porphyrin MOFs exhibit rapid electron-hole recombination, resulting in low photodynamic antibacterial efficiency.

[0004] In recent years, gold nanoparticles (Au NPs) have demonstrated tremendous potential in photocatalysis due to their unique surface plasmon resonance (SPR) effect and excellent electron transport properties. Numerous studies have demonstrated that Au NPs not only significantly enhance the material's light-harvesting ability and promote the efficient separation and migration of photogenerated charge carriers, but also effectively reduce the activation energy of reactions due to their abundant surface active sites. Particularly noteworthy is the fact that Au NPs exhibit various nanozyme activities, such as peroxidase- and oxidase-like activities, which opens new avenues for their application in biocatalysis.

[0005] As ideal nanocarriers, porphyrin-based metal-organic frameworks (MOFs) provide an ideal platform for the uniform dispersion and stable loading of AuNPs due to their highly ordered pore structure, tunable specific surface area, and excellent photoelectric properties. This unique composite structure not only maximizes the exposure of the active sites of AuNPs, but also significantly promotes the directional separation and rapid transport of photogenerated electron-hole pairs through interfacial synergistic effects. Studies have confirmed that AuNPs-MOFs composites not only exhibit excellent photocatalytic performance, but their enhanced nanozyme activity also gives them broad application prospects in fields such as environmental remediation and biomedicine. The development of this multifunctional nanocomposite provides innovative ideas for the design of efficient catalytic systems. On the other hand, the introduction of glucose oxidase (GOx) can catalyze the production of hydrogen peroxide (H2O2) from glucose in the bacterial microenvironment, thereby enhancing the photodynamic effect and inhibiting the proliferation of bacteria by cutting off their energy supply ("starvation therapy").

[0006] Furthermore, thermosensitive hydrogels, due to their temperature-responsive sol-gel transition properties, are ideal medical dressing materials. At body temperature, injectable hydrogels can form a protective gel layer in situ, tightly adhering to the wound and continuously releasing antimicrobial ingredients. By combining light-responsive nanoantimicrobial materials with thermosensitive hydrogels, a synergistically enhanced antimicrobial effect can be achieved, providing a new strategy for the development of intelligent antimicrobial dressings.

[0007] Based on the above technical background, the present invention proposes a PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel, which integrates the multimodal antibacterial mechanism of photodynamic therapy, enzymatic cascade catalysis, and starvation therapy, and utilizes the reversible sol-gel phase transition behavior and adaptability of the thermosensitive hydrogel. It can spontaneously form a three-dimensional network gel structure under body temperature conditions (about 37°C), perfectly fitting various complex shapes of wounds and achieving tight coverage, thereby providing an efficient, safe, and intelligent new antibacterial dressing suitable for the treatment of wounds infected with drug-resistant bacteria. Summary of the Invention

[0008] In order to make up for the deficiencies in the prior art, the present invention is conceived as follows:

[0009] MOFs (metal-organic frameworks) are a class of crystalline porous materials with periodic network structures formed by the self-assembly of transition metal ions and organic ligands. They possess other unique characteristics, including unique chemical composition, POD enzyme activity, ordered porous structure, large specific surface area, and tunable structure. This makes MOFs suitable for a variety of applications, such as gas storage and separation, catalytic bioreactions, and drug release. Their applications in catalysis have garnered significant attention. However, MOF frameworks possess a limited number of catalytically active sites, limiting the range of reactions they can catalyze. Utilizing the permanent pores of MOF materials to confine guest species, particularly metal nanoparticles (MNPs), can effectively enhance catalytic performance and expand the application of MOF-based catalysts in diverse reactions. Gold (Au) is one of the most chemically stable elements, and AuNPs exhibit a variety of enzyme-like activities, such as POD, CAT, SOD, and oxidase-like activities. They can alleviate oxidative stress and hypoxia in diabetic wounds. Furthermore, the abundant oxygen (O2) can promote angiogenesis, collagen deposition, cell proliferation and migration, and accelerate wound repair. Au NPs-MOFs retain the high surface area, pore volume, and porosity of MOFs while enabling uniform dispersion of AuNPs, improving stability and longevity. Combining the advantages of metal-organic frameworks and metal nanoparticles, they synergistically enhance catalytic performance. However, the high blood sugar and high pH environment in diabetic wounds limits the catalytic activity of AuNPs-MOFs. Therefore, optimal catalytic performance requires depletion of glucose from the wound site and a lowering of the pH. Hydrogels integrate GOx and nanozymes with POD activity, creating a self-activated enzymatic cascade reaction. GOx, a natural enzyme, decomposes glucose to produce H2O2 and gluconic acid, lowering the wound pH and creating an acidic microenvironment. Under photocatalysis, the nanozymes decompose the generated H2O2 into ·OH as a result of the cascade reaction. Furthermore, hydrogels maintain wound moisture, creating a slightly acidic environment, and accelerating wound healing. Unlike traditional dressings, which absorb exudate and adhere to tissue after drying, causing significant pain for the patient, hydrogels can alleviate wound pain. After absorbing wound exudate, they absorb wound exudate without loosening or breaking, leaving no residue. When removing the dressing, it will not stick to the wound surface, thus avoiding secondary damage to the wound surface.

[0010] The present invention provides a PCN@Au / GOx-F68 / F127 photocatalytic antibacterial temperature-sensitive hydrogel, a preparation method thereof, and an application thereof.

[0011] A PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel. The photocatalytic antibacterial material is a cube with a rough surface and a diameter ranging from 70 to 150 nm.

[0012] A gold nanoparticle-modified zirconium-porphyrin metal-organic framework (PCN@Au) nanozyme was constructed using an in situ growth method. Under acidic conditions, it exhibits POD-like and oxidase-like activities, degrading endogenous H₂O₂ to produce ROS and exhibiting strong antibacterial activity. However, hyperglycemic environments limit the application of PCN@Au in diabetic wound healing. GOx, as a natural enzyme, degrades glucose to produce H₂O₂ and gluconic acid. H₂O₂ is further catalyzed by the POD-like activity of PCN@Au to ·OH, leading to glucose consumption and bacterial death. This avoids the direct use of toxic H₂O₂ and reduces the pH at the wound site to 5-6, overcoming the pH limitation on POD-like activity. Therefore, in this study, a gold nanoparticle-modified zirconium-porphyrin metal-organic framework (PCN@Au) nanozyme with POD-like and oxidase-like activities was prepared. PCN@Au was further integrated with the natural enzyme GOx to prepare a PCN@Au / GOx-F68 / F127 thermosensitive hydrogel with good biocompatibility, which promoted diabetic wound healing through a self-oxygenation cascade reaction.

[0013] The present invention also provides a PCN@Au / GOx-F68 / F127 photoresponsive antibacterial thermosensitive material for use in inactivating methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase-producing Escherichia coli (ESBL). The hydrogel is added to a bacterial solution containing MRSA and ESBL, and the solution is irradiated with a 420nm xenon laser for 0-30 minutes.

[0014] Furthermore, in the above application, in one embodiment, the dosage of PCN@Au / GOx-F68 / F127 hydrogel is 100 μg, the volume of MRSA and ESBL bacterial solution is 200 μL, and the concentration of the bacterial solution is 10 6 In other application embodiments, the above dosage ratio can be used to increase or decrease the amount by the same multiple.

[0015] The present invention also provides a method for preparing PCN@Au / GOx-F68 / F127 photocatalytic antibacterial thermosensitive hydrogel, comprising the following steps:

[0016] S1. Synthesis of TCPP

[0017] 4-Carboxybenzaldehyde and pyrrole are ultrasonically dispersed in propionic acid and refluxed in the dark for a period of time to obtain a black solution. After the solution cools, methanol is added to the reaction solution, and the mixture is stirred in an ice-water bath. After the reaction is completed, the solution is filtered and washed alternately with methanol and deionized water. The resulting product is dried in a vacuum drying oven to obtain a purple powder, TCPP.

[0018] S2. Synthesis of PCN

[0019] Disperse ZrOCl2·8H2O and benzoic acid in DMF and sonicate for 5-30 minutes. Then add TCPP and sonicate for 5-30 minutes. Place the mixed solution in a reactor at 100-150°C for 24-48 hours, cool to room temperature, centrifuge, and wash 2-5 times each with DMF and anhydrous ethanol before drying in an oven. Add the synthesized sample and HCl to DMF, heat and stir, then disperse the product in acetone and stir at this temperature for 24-48 hours. After centrifugation to remove the acetone, dry the solid sample in a vacuum at 60-150°C for 24-72 hours.

[0020] S3. Synthesis of PCN@Au

[0021] Dissolve PCN in deionized water, add HAuCl4 solution, stir in an ice-water bath at 0-10°C, then add NaBH4 solution dropwise at a rate of 0.1-1 mL / min, stir rapidly for 0.5-4 h, and then wash with deionized water 3-6 times to obtain PCN@Au.

[0022] S4: Synthesis of PCN@Au / GOx-F68 / F127 Hydrogel

[0023] Weigh 3% Pluronic F-127 and Pluronic F-68 and add them to deionized water until F68 and F127 are completely dissolved in the deionized water. This creates an F68 / F127 hydrogel. Using a one-pot method, a PCN@Au / GOx solution of a specific concentration is added to the F68 / F127 hydrogel to prepare a PCN@Au / GOx-F68 / F127 composite hydrogel.

[0024] Furthermore, the specific steps of the synthesis of step S1.TCPP are as follows: 3.04-6.08 g of 4-carboxybenzaldehyde and 1.4-2.8 g of pyrrole are weighed, ultrasonically dispersed in 75-150 mL of propionic acid, and refluxed at 100-135° C. for 2-4 hours in the dark to obtain a black solution. After the solution is cooled to room temperature, 100-200 mL of methanol is added to the reaction solution, and stirred in an ice-water bath for 30-60 minutes. After the reaction is completed, the mixture is washed alternately with methanol and deionized water three times by suction filtration. The obtained product is dried in a vacuum drying oven at 80° C. for 12-24 hours to obtain a purple powder, which is TCPP.

[0025] Furthermore, the specific steps of the synthesis of step S2.PCN are as follows: 3.04-6.08 g of 4-carboxybenzaldehyde and 1.4-2.8 g of pyrrole are weighed, ultrasonically dispersed in 75-150 mL of propionic acid, and refluxed at 100-135° C. for 2-4 hours in the dark to obtain a black solution. After the solution is cooled to room temperature, 100-200 mL of methanol is added to the reaction solution, and stirred in an ice-water bath for 30-60 minutes. After the reaction is completed, the mixture is washed alternately with methanol and deionized water three times by suction filtration. The obtained product is dried in a vacuum drying oven at 80° C. for 12-24 hours to obtain a purple powder, which is TCPP.

[0026] PCN Activation: The synthesized sample (50-200 mg) and 1-3 mL of 6-10 M HCl (added dropwise) were added to 20-50 mL of DMF. The DMF suspension was stirred at 60-150°C for 6-24 hours to remove unreacted starting ligands, inorganic materials, and modifiers. Subsequently, the extract was carefully decanted and the product was dispersed in acetone and stirred at 10-40°C for 12-48 hours to exchange and remove the DMF. After centrifugation to remove the acetone, the solid sample was dried under vacuum at 60-150°C for 12-72 hours.

[0027] Furthermore, the specific steps for synthesizing PCN@Au in step S3 are as follows: 5-20 mg of PCN was dissolved in 20 mL of deionized water. The PCN-224 solution was placed in a 0-10°C ice-water bath, 50-200 μL of 10-100 mM HAuCl4 was added, and pre-stirred for 2-10 minutes. Then, 0.5-2 mL of freshly prepared ice-cold NaBH4 solution (1-3 mg / mL) was dropwise added. The reaction was rapidly stirred for a total reaction time of 0.5-4 hours, and then washed with deionized water 2-6 times to obtain PCN@Au.

[0028] Furthermore, the specific steps for synthesizing the PCN@Au / GOx-F68 / F127 hydrogel in step S4 are as follows: A F68 / F127 composite hydrogel dressing was prepared using a cooling method. 25-40% (w / w) Pluronic F-127 and 2-8% (w / w) Pluronic F-68 were weighed and added to deionized water. The resulting mixture was transferred to a refrigerator at 2-8°C and reacted for 12-24 hours until F68 and F127 were completely dissolved in the deionized water. Thus, the F68 / F127 hydrogel was prepared. A PCN@Au / GOx solution of a certain concentration was added to the F68 / F127 hydrogel using a one-pot method and vortexed to uniformly disperse the GOx into the F68 / F127 hydrogel network (this process was always performed in a 4°C cooling bath). This resulted in the preparation of a PCN@Au / GOx-F68 / F127 composite hydrogel.

[0029] A multifunctional hydrogel, PCN@Au / GOx-F68 / F127, which promotes wound healing through a cascade reaction of antibacterial activity led by photodynamic therapy, was used to treat infected wounds in diabetic mice, in which PCN was used to construct a nanoplatform with photocatalytic and antibacterial activity. First, NaBH4 was used to reduce the Au(III) precursor diffused into the PCN to Au cores, which grew into AuNPs to form PCN@Au. PCN@Au produced high levels of ROS through POD and PDT under xenon lamp irradiation and killed bacteria by catalyzing the production of ROS at relatively low temperatures (<37°C). The combination of multiple modes can avoid the biotoxicity of dose-dependent materials. Subsequently, PCN@Au was encapsulated with GOx in the hydrogel according to similar methods in previous reports to achieve uniform distribution in the wound and moisturizing effect on the wound. In this work, GOx decomposes glucose to produce H2O2 and gluconic acid through a glucose-activated cascade reaction. It is expected that PCN@Au will inherit the POD and oxidase-like catalytic activity of AuNPs and catalyze the production of ·OH and O2 under the high concentration of endogenous H2O2 at the wound site for enhanced photodynamic therapy. At the same time, the hydrogel makes up for the shortcomings of traditional wound dressings and is a promising biomaterial with high water content, excellent porosity and soft consistency, which can provide a moist and adhesive environment.

[0030] Compared with the existing technology, the present invention has the following advantages:

[0031] 1. The preparation method of PCN@Au / GOx-F68 / F127 hydrogel provided by the present invention has mild synthesis conditions, simple process and is economically feasible.

[0032] 2. The PCN@Au / GOx-F68 / F127 hydrogel provided by the present invention can realize self-activated enzymatic reaction and photodynamic synergistic antibacterial effect, reducing side effects while improving antibacterial efficiency.

[0033] 3. The PCN@Au / GOx-F68 / F127 hydrogel provided by this invention is thermosensitive and, as a self-activating enzymatic reaction platform, can also alleviate wound pain. After absorbing wound exudate, it does not loosen or break, leaving no residue. When the dressing is removed, it does not adhere to the wound surface, preventing secondary damage to the wound surface.

[0034] This hydrogel can transition from gel to sol at temperatures between 4 and 37°C. PCN@Au nanozymes are constructed using an in situ growth method and, after integration with GOx, form a self-activating enzymatic cascade within the hydrogel. GOx decomposes glucose to produce H₂O₂ and gluconic acid, lowering wound pH. PCN@Au, under acidic conditions, decomposes endogenous H₂O₂ to produce ROS, killing bacteria. This avoids the limitations of high blood sugar and high pH on catalytic activity and simultaneously achieves photodynamic synergistic antibacterial activity. The preparation method features mild synthesis conditions, a simple process, and economic feasibility. The hydrogel is thermosensitive, reduces wound pain, absorbs exudate without loosening or residue, and does not adhere to the wound surface upon removal. Under irradiation with a 420nm xenon lamp for 0-30 minutes, it effectively inactivates methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Escherichia coli, providing a new approach for the treatment of diabetic bacterial wounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The XRD pattern of the nano antibacterial agent PCN@Au prepared in Example 1, (a) is the original XRD pattern, and (b) is a local enlarged pattern;

[0036] Figure 2 TEM images of the nano antibacterial agent PCN@Au prepared in Example 1, (a) is PCN, (b, c) are PCN@Au;

[0037] Figure 3 Thermosensitivity and injectability of PCN@Au / GOx-F68 / F127 hydrogel. (a, b) are the sol-gel transition properties of PCN@Au / GOx-F68 / F127 hydrogel, and (c, d) are the injectability of PCN@Au / GOx-F68 / F127 hydrogel.

[0038] Figure 4 Determination of enzyme-like properties of PCN@Au / GOx-F68 / F127 hydrogel: (a) is the oxidase-like activity; (b) is the oxidase-like activity of the material under dark and light conditions; (c) is the POD enzyme activity;

[0039] Figure 5 Antibacterial properties of PCN@Au / GOx-F68 / F127 hydrogels: (a) antibacterial plate images of different materials irradiated with visible light for different times, (b) photocatalytic antibacterial rate;

[0040] Figure 6 Broad-spectrum antibacterial properties of PCN@Au / GOx-F68 / F127 hydrogel: (a) is the broad-spectrum antibacterial plate diagram, and (b) is the photocatalytic broad-spectrum antibacterial rate. DETAILED DESCRIPTION

[0041] In order to better understand the content of the present invention, the present invention will be further described below in conjunction with specific implementation cases. The following examples are implemented based on the technology of the present invention, combined with detailed implementation methods and operating steps, but the protection scope of the present invention is not limited to the following examples. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0042] Example 1

[0043] S1. Synthesis of TCPP

[0044] Weigh 6.08g of 4-carboxybenzaldehyde and 2.8g of pyrrole and ultrasonically disperse them in 150mL of propionic acid. Reflux at 135°C in the dark for 2 hours to obtain a black solution. After the solution cools to room temperature, add 200mL of methanol to the reaction mixture and stir in an ice-water bath for 30 minutes. After the reaction is complete, filter and rinse three times with methanol and deionized water, respectively. Dry the resulting product in a vacuum drying oven at 80°C for 12 hours to obtain a purple powder, TCPP.

[0045] S2. Synthesis of PCN

[0046] The specific steps for synthesizing PCN are as follows: 600 mg of ZrOCl2·8H2O and 8 g of benzoic acid were weighed and dispersed in 40 mL of DMF in a conical flask. The mixture was sonicated for 10 minutes. 200 mg of TCPP was then added and sonicated for 10 minutes. The mixed solution was placed in a reactor at 120°C for 24 hours, cooled to room temperature, centrifuged at 8000 rpm for 10 minutes, and the supernatant was decanted. The mixture was then washed three times with DMF and anhydrous ethanol, and then dried in an oven.

[0047] PCN Activation: The synthesized sample (100 mg) and 1.5 mL of 8 M HCl (added dropwise) were added to 40 mL of DMF. The DMF suspension was stirred at 120°C for 12 h to remove unreacted starting ligands, inorganic materials, and modifiers. Subsequently, the extract was carefully decanted and the product was dispersed in acetone and stirred at room temperature for 24 h to exchange and remove the DMF. After centrifugation to remove the acetone, the solid sample was dried in vacuo at 120°C for 24 h.

[0048] S3. Synthesis of PCN@Au

[0049] Dissolve 10 mg of PCN in 20 mL of deionized water. Place the PCN-224 solution in an ice-water bath, add 100 μL of 50 mM HAuCl₄, and stir for 4 minutes. Then, add 1 mL of freshly prepared ice-cold NaBH₄ solution (1.75 mg / mL) dropwise. Stir rapidly for 2 hours, and then wash several times with deionized water to obtain PCN@Au.

[0050] S4: Synthesis of PCN@Au / GOx-F68 / F127 hydrogel.

[0051] The F68 / F127 composite hydrogel dressing was prepared using a cooling method. 32% (w / w) Pluronic F-127 and 4% (w / w) Pluronic F-68 were weighed and added to deionized water. The resulting mixture was transferred to a 4°C refrigerator overnight until F68 and F127 could be completely dissolved in deionized water. Thus, the F68 / F127 hydrogel was prepared. A certain concentration of PCN@Au / GOx solution was added to the F68 / F127 hydrogel using a one-pot method and vortexed to evenly disperse GOx into the F68 / F127 hydrogel network (this process was always carried out in a cold bath at 4°C). The PCN@Au / GOx-F68 / F127 composite hydrogel was prepared.

[0052] Example 2

[0053] The crystal structures of the samples in Example 1 were analyzed by XRD. X-ray diffraction data for all samples were collected using a LabX XRD-6000 X-ray diffractometer (Shimadzu Corporation, Japan). The experiment used a Cu target radiation (λ = 0.15405 nm) as the radiation source, and scanned the crystal structures of the materials at a rate of 2° / min over a 2θ range of 6-80°. Figure 1 a The characteristic peaks of PCN and Au appear, and the main diffraction peaks of Au, including (111), (200), (220) and (311), are fully observed in the XRD pattern, proving the successful preparation of PCN@Au.

[0054] Example 3

[0055] The morphology and microstructure of the samples in Example 1 were analyzed by TEM. The TEM images were taken by a JEM-2100 transmission electron microscope (JEOL Ltd.). Figure 2 It can be seen that a single PCN is a nanoparticle with a size of about 150 nm, a smooth surface and a cubic morphology; after loading Au nanoparticles, it becomes a cube with an uneven surface. The Au nanoparticles are smaller in size, relatively uniform, about 10 nm, and evenly dispersed.

[0056] Example 4

[0057] The oxidase-like and POD-like activities of the composite were measured in sodium acetate buffer using TMB (3,3′,5,5′-tetramethylbenzidine) as the oxidizing substrate. PCN@Au exhibited significant catalytic performance in the absence of H₂O₂. Comparing the enzyme-like activity of the material under light-exposed and dark-protected conditions, the catalytic oxidase-like activity under light-exposed conditions was significantly greater. The addition of H₂O₂ to the system enhanced the catalytic performance of PCN@Au, further confirming its ability to effectively catalyze the generation of ·OH.

[0058] Example 5

[0059] The samples in Example 1 were placed in glass vials, and the ambient temperature was changed. When the temperature was 4°C, the F68 / F127 hydrogel and PCN@Au / GOx@F68 / F127 hydrogel were highly fluid liquids. When the temperature rose to 37°C, the two hydrogels immediately turned into gel-like solids. By changing the proportion of F127, the gelation temperature of the hydrogel also changed. The gelation temperature was between 20-37°C, and both hydrogels did not flow under the influence of gravity and remained in a gel state. This shows that both hydrogels can remain in the wound area and will not fall off due to gravity. It was also noted that when the temperature dropped to 4°C, the two hydrogels turned into liquid again, indicating that the F68 / F127 hydrogel and PCN@Au / GOx@F68 / F127 hydrogel have reversible sol-gel transition properties ( Figure 4 a, b). The F68 / F127 hydrogel can be smoothly extruded from the syringe at room temperature without resistance and can form the letter "A", indicating that the hydrogel has excellent injectability ( Figure 4 c).

[0060] Example 6

[0061] Using extended-spectrum β-lactamase-producing Escherichia coli (ESBL), the most common pathogenic bacterium among drug-resistant bacteria, as a model strain, the plate count method was used to investigate the antibacterial activity of the prepared composite hydrogel under visible light irradiation. The bacterial suspension concentration was adjusted to 1×107 CFU / mL as the initial photocatalytic bacterial concentration. The total reaction system, 2 mL, contained 200 μL of bacterial suspension, 100 μL of a 2 mg / mL aqueous solution of the composite hydrogel, and 100 μL of a 200 mM glucose solution. The remainder was made up to 2 mL with PBS. The mixed solution was illuminated with a xenon lamp (300 W) for 30 minutes. After the reaction, the solution was diluted 1000-fold, and 50 μL was spread on LB solid medium and incubated in a 37°C incubator for 12 hours. Each experiment was repeated three times.

[0062] Calculate the photocatalytic antibacterial rate.

[0063] Antibacterial rate = (number of colonies before illumination - number of colonies after illumination) / number of colonies before illumination×100％

[0064] Application Example 1

[0065] The following is the application of the PCN@Au / GOx@F68 / F127 hydrogel prepared in Example 1 to inactivate ESBL under 420nm visible light laser irradiation. The specific process is as follows:

[0066] The most common pathogenic bacteria among drug-resistant bacteria, extended-spectrum β-lactamase-producing Escherichia coli (ESBL), was used as a model strain. The plate count method was used to study the antibacterial activity of the prepared composite hydrogel under visible light irradiation. The concentration of the bacterial suspension was adjusted to 1×10 7 CFU / mL was used as the initial photocatalytic bacterial concentration. The total reaction system was 2 mL, containing 200 μL of bacterial suspension, 100 μL of composite hydrogel (2 mg / mL) aqueous solution, and 100 μL of glucose solution (200 mM). The remainder was made up to 2 mL with PBS. The mixed solution was illuminated by a xenon lamp (300 W) for 30 minutes. After the reaction was completed, it was diluted 1000 times and 50 μL was spread on LB solid culture medium and incubated in a 37°C incubator for 12 hours. Each experiment was repeated three times.

[0067] Calculate the photocatalytic antibacterial rate.

[0068] Antibacterial rate = (number of colonies before illumination - number of colonies after illumination) / number of colonies before illumination ×100％

[0069] Observe the bacterial morphology at any time, and count the number of colonies on each culture medium after the colonies grow to the ideal size. Figure 6 It can be seen that the colony count in the blank group under the three conditions did not decrease significantly, and even showed negative growth, indicating that temperature and light alone do not have a significant impact on bacteria; under the synergistic effect of PDT / PTT, ESBLE.coli and MRSA can achieve a sterilization rate of more than 99% in 10-45 minutes.

[0070] The above description is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel, characterized in that: The photocatalytic antibacterial material PCN@Au is a nanoparticle with a size ranging from 70 to 150 nm and a rough surface. The hydrogel is temperature-sensitive and can complete the transformation between gel and sol under conditions of 4-37°C.

2. A method for preparing PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel, characterized in that: The steps include: S1. Synthesis of PCN Take ZrOCl2·8H2O and benzoic acid and disperse them in DMF. Ultrasonic treatment is carried out for 5-30 minutes. TCPP is then added and ultrasonic treatment is carried out for 5-30 minutes. The mixed solution is placed in a reactor and reacted at 100-150°C for 24-48 hours. The mixture is cooled to room temperature, centrifuged, washed with DMF and anhydrous ethanol, and then dried. The synthesized sample and HCl are added to DMF, heated and stirred, and the product is dispersed in acetone and stirred for 24-48 hours. After centrifugation to remove the acetone, the solid sample is vacuum dried at 60-150°C for 24-72 hours. S2. Synthesis of PCN@Au PCN was dissolved in deionized water, and a certain amount of HAuCl4 solution was added. The mixture was stirred in an ice-water bath at 0-10°C, and then a certain amount of NaBH4 solution was added dropwise. The mixture was rapidly stirred for 0.5-4 hours, and then washed with deionized water to obtain PCN@Au. S3: Synthesis of PCN@Au / GOx-F68 / F127 Hydrogel A certain amount of Pluronic F-127, Pluronic F-68 and PCN@Au / GOx in different proportions were weighed and added into deionized water to prepare PCN@Au / GOx-F68 / F127 composite hydrogels with different compositions and phase transition temperatures.

3. The method for preparing the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 2, characterized in that: The method also includes the step of synthesizing TCPP: 4-carboxybenzaldehyde and pyrrole are ultrasonically dispersed in propionic acid, and the mixture is refluxed in the dark for a period of time to obtain a black solution. After the solution is cooled, methanol is added to the reaction solution, and the mixture is stirred in an ice-water bath. After the reaction is completed, the mixture is filtered and washed alternately with methanol and deionized water. The obtained product is dried in a vacuum drying oven to obtain a purple powder, which is TCPP.

4. The method for preparing the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 3, wherein: The specific steps of synthesizing the TCPP are as follows: weighing 3.04-6.08 g of 4-carboxybenzaldehyde and 1.4-2.8 g of pyrrole, ultrasonically dispersing them in 75-150 mL of propionic acid, and refluxing them at 100-135° C. for 2-4 hours in the dark to obtain a black solution. After the solution is cooled to room temperature, 100-200 mL of methanol is added to the reaction solution, and the mixture is stirred in an ice-water bath for 30-60 minutes. After the reaction is completed, the mixture is filtered and washed alternately with methanol and deionized water. The obtained product is dried in a vacuum drying oven at 80° C. for 12-24 hours to obtain a purple powder, which is TCPP.

5. The method for preparing the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 2, characterized in that: The specific steps of synthesizing the PCN are as follows: weighing 3.04-6.08 g of 4-carboxybenzaldehyde and 1.4-2.8 g of pyrrole, ultrasonically dispersing them in 75-150 mL of propionic acid, and refluxing them at 100-135° C. for 2-4 hours in the dark to obtain a black solution. After the solution is cooled to room temperature, 100-200 mL of methanol is added to the reaction solution, and the mixture is stirred in an ice-water bath for 30-60 minutes. After the reaction is completed, the mixture is filtered and washed alternately with methanol and deionized water. The obtained product is dried in a vacuum drying oven at 80° C. for 12-24 hours to obtain a purple powder, which is TCPP.

6. The method for preparing the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 2, characterized in that: Step S2 also includes activation of PCN: 50-200 mg of the synthesized sample and 1-3 mL of 6-10 M HCl are added dropwise to 20-50 mL of DMF, and the DMF suspension is stirred at 60-150° C. for 6-24 h to remove unreacted starting ligands, inorganic substances, and regulating reagents. The extract is decanted and the product is dispersed in acetone and stirred at 10-40° C. for 12-48 h to exchange and remove DMF. After centrifugation to remove acetone, the solid sample is vacuum dried at 60-150° C. for 12-72 h.

7. The method for preparing the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 2, characterized in that: The specific steps of synthesizing PCN@Au in the step are as follows: dissolving 5-20 mg PCN in 20 mL deionized water, placing the PCN-224 solution in a 0-10°C ice water bath, adding 50-200 μL 10-100 mM HAuCl4, pre-stirring for 2-10 minutes, then dropwise adding 0.5-2 mL freshly prepared ice-cold NaBH4 solution, rapidly stirring for a total reaction time of 0.5-4 hours, and then washing with deionized water to obtain PCN@Au.

8. The method for preparing the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 2, characterized in that: The specific steps of synthesizing the PCN@Au / GOx-F68 / F127 hydrogel in the step are as follows: 25-40% (w / w) of Pluronic F-127 and 2-8% (w / w) of Pluronic F-68 are weighed and added to deionized water, and then different amounts of PCN@Au / GOx are added. The resulting mixture is transferred to a refrigerator at 2-8°C and reacted for 12-24 hours until F68 and F127 can be completely dissolved in deionized water to prepare the PCN@Au / GOx-F68 / F127 composite hydrogel.

9. Application of PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel, characterized in that: It is used to inactivate a variety of Gram-positive and Gram-negative bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase-producing Escherichia coli (ESBL), as well as a variety of fungi.

10. The use of the PCN@Au / GOx-F68 / F127 antibacterial thermosensitive hydrogel according to claim 9, characterized in that: The sterilization conditions are as follows: add PCN@Au / GOx-F68 / F127 composite hydrogel to the bacterial solution containing the target bacteria, irradiate the bacterial solution under a xenon lamp laser (>420nm) for 0-30min, the amount of PCN@Au / GOx-F68 / F127 composite hydrogel is 0-500μL, the volume of the bacterial solution is 50-1000μL, and the concentration of the bacterial solution is 10-10 10 CFU / mL.

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