pH-responsive antibacterial hydrogel and preparation method and application thereof

Abstract

This invention relates to the field of biomedical technology and discloses a pH-responsive antibacterial hydrogel, its preparation method, and its applications. By introducing a PDA-CeO2 nanocomposite material into a hydrogel system containing dynamic borate ester bonds, the PDA photothermal effect is utilized to physically disrupt bacterial biofilms, enhancing the antibacterial effect. Simultaneously, CeO2 nanoparticles catalyze the production of endogenous H2O2 oxygen and remove ROS, simultaneously alleviating wound hypoxia and oxidative stress. The pH-responsive dynamic borate ester bonds enable intelligent on-demand release of therapeutic components within the infected microenvironment and endow the material with self-healing properties. Furthermore, the moisturizing properties of hyaluronic acid and the catechol groups of dopamine enhance the hydrogel's adhesion to moist wounds, maintaining ideal healing humidity. This solves the technical problems of existing burn dressings, such as limited functionality, lack of intelligent responsiveness, and difficulty in synergistically regulating the complex wound microenvironment.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, specifically to a pH-responsive antibacterial hydrogel, its preparation method, and its application. Background Technology

[0002] Burns, especially deep second- and third-degree burns, are a common and severe form of trauma in clinical practice. Due to the disruption of the skin barrier, tissue necrosis, and protein-rich exudate, the wound surface easily becomes a breeding ground for bacteria (such as Staphylococcus aureus and Pseudomonas aeruginosa), leading to infection. Bacteria further form a biofilm on the wound surface, significantly enhancing their resistance to antibiotics and the host's immune system, causing persistent infection and inflammatory responses. In addition, burn wounds are often accompanied by severe oxidative stress, local hypoxia (due to microvascular damage and high bacterial metabolic consumption), and an imbalanced immune microenvironment. These factors collectively lead to delayed wound healing, scar hyperplasia, and even systemic sepsis, among other serious consequences.

[0003] Currently, there are many types of dressings used in clinical practice for burn wounds, such as traditional gauze, foam dressings, hydrocolloid dressings, and silver ion dressings. These dressings mainly serve to physically cover, absorb exudate, and provide passive anti-infection (such as silver ion release). However, they generally have the following limitations: (1) Single function: It is difficult to simultaneously meet multiple complex needs such as anti-infection, relief of oxidative stress, regulation of immunity, and promotion of tissue regeneration. (2) Lack of intelligent responsiveness: It is impossible to achieve on-demand and precise release of therapeutic components according to the special infection and inflammatory microenvironment of burn wounds (such as local pH decrease, reactive oxygen species (ROS) overload, and increased concentration of specific enzymes), which may lead to drug waste or local toxicity. (3) Insufficient ability to deal with biofilms: Traditional antibacterial agents have limited penetration and removal effects on mature biofilms. (4) Contradiction between adhesion and moisturization: On moist burn wounds, many dressings have poor adhesion and are easy to shift; while maintaining appropriate moisture in the wound to promote healing is a basic principle of modern wound management.

[0004] In recent years, the combination of nanotechnology and smart hydrogels has brought new ideas to burn wound management. Polydopamine (PDA) is widely used in antibacterial materials due to its excellent photothermal conversion properties, adhesion, and biocompatibility. Cerium dioxide (CeO2) nanoparticles possess unique catalase-like and superoxide dismutase-like activities, which can catalyze the decomposition of excess hydrogen peroxide in the wound to produce oxygen (O2), while simultaneously scavenging superoxide anion free radicals, thereby alleviating hypoxia and oxidative stress. However, how to effectively combine the advantages of PDA and CeO2 and integrate them into a hydrogel system that can intelligently respond to the burn wound microenvironment and has efficient antibacterial, oxygen supply, antioxidant, and healing-promoting functions still lacks a mature and efficient solution.

[0005] Existing technologies, such as Chinese patent application CN120733112A, disclose a method for preparing and applying a Janus-structured photothermal-piezoelectric hydrogel dressing for repairing infected wounds. This method employs a temporally separated, linear dual-module system within a Janus bilayer structure, achieving a stepwise effect of photothermal antibacterial action of the inner layer MXene@CeO2 and piezoelectric repair promotion of the outer layer BaTiO3 through spatial partitioning. However, the Janus structure layers of this hydrogel dressing are easily separated, and the inner layer can only release medication burstily, resulting in poor responsive release and sustained chemical regulation. Furthermore, this hydrogel dressing only linearly superimposes functions on two aspects: wound infection and cell behavior regulation, lacking a synergistic coupling design between modules. It does not address the core pathological disorders of hypoxia and oxidative stress in burn wounds, nor does it have a positive feedback mechanism between functions. In addition, the preparation process of this hydrogel dressing is complex, making large-scale production difficult.

[0006] Therefore, developing a novel composite hydrogel dressing that integrates intelligent responsive release, synergistic antibacterial-oxygen-antioxidant properties, good biocompatibility, and mechanical properties is of great clinical significance and application value for breaking through the current bottlenecks in burn wound treatment, improving healing quality, and reducing the risk of complications. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a pH-responsive antibacterial hydrogel, its preparation method, and its applications. By introducing a PDA-CeO2 nanocomposite material into a hydrogel system containing dynamic borate ester bonds, on the one hand, the photothermal effect of PDA is used to physically disrupt bacterial biofilms, enhancing the antibacterial effect; on the other hand, CeO2 nanoparticles catalyze the production of endogenous H2O2 oxygen and remove ROS, simultaneously alleviating wound hypoxia and oxidative stress; at the same time, the pH-responsive dynamic borate ester bonds enable the intelligent on-demand release of therapeutic components in the infection microenvironment and endow the material with self-healing properties.

[0008] The pH-responsive antibacterial hydrogel prepared by this invention also utilizes the moisturizing properties of hyaluronic acid and the catechol groups of dopamine to enhance the adhesion of the hydrogel to moist wounds, thereby maintaining ideal healing humidity of the wound, improving oxygen supply and clearing ROS, regulating macrophage polarization, and promoting the transformation of the wound from the inflammatory phase to the proliferative repair phase. This solves the technical problems of existing burn dressings having single functions, lacking intelligent responsiveness, and being difficult to synergistically regulate the complex wound microenvironment.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a pH-responsive antibacterial hydrogel includes the following steps: Step (1) Preparation of CeO2 nanoparticles Ce(NO3)3·6H2O was dissolved in water and stirred until completely dissolved. After the reaction was completed, the mixture was purified to obtain CeO2 nanoparticles. Step (2): Preparation of PDA-CeO2 nanocomposite material CeO2 nanoparticles were dispersed in water and ultrasonically dispersed. Dopamine hydrochloride was added and reacted. After the reaction was completed, the product was purified by centrifugation, washed, and dried to obtain PDA-CeO2 nanocomposite material. Step (3) Preparation of HA-PBA The pH of the hyaluronic acid (HA) aqueous solution was adjusted to 5-6. Then, 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) aqueous solution and N-hydroxysuccinimide (NHS) aqueous solution were added sequentially. PBS buffer containing 3-aminophenylboronic acid (3-APBA) was added dropwise. After the reaction was completed, the solution was purified to obtain HA-PBA. Step (4): Preparation of PDA-CeO2@HA-PBA composite hydrogel HA-PBA was mixed with water to prepare an aqueous solution of HA-PBA; PDA-CeO2 nanocomposite material was mixed with water to prepare an aqueous dispersion of PDA-CeO2. A HA-PBA aqueous solution was mixed with a PDA-CeO2 aqueous dispersion and crosslinked. After the reaction was completed, a pH-responsive antibacterial hydrogel was obtained.

[0010] Preferably, in step (1): Ce(NO3)3 The mass ratio of 6H2O to water is (1.70-1.75):(45-55); the reaction conditions are: adjust the pH of the system to 9.0-11.0, continue stirring for 2-3 hours to form a white precipitate, and transfer the mixture to a high-pressure reactor to react at 110-130℃ for 10-12 hours.

[0011] Preferably, in step (1), the purification process includes: natural cooling, centrifugation to collect the precipitate, washing with water and ethanol alternately, and vacuum drying.

[0012] Preferably, in step (2), the mass ratio of CeO2 nanoparticles, water, and dopamine hydrochloride is (0.1-0.2):(100-120):(0.04-0.08); the reaction conditions are: adjusting the pH of the system to 8.0-8.5 with Tris-HCl buffer, and stirring the reaction at room temperature in the dark for 16-20 hours.

[0013] Preferably, in step (2), the purification process includes: centrifuging to collect the product, washing it alternately with water and ethanol, and then freeze-drying it.

[0014] Preferably, in step (3), the reaction conditions are: under light-protected conditions, the reaction is stirred at 35-38°C for 45-50 hours, and the pH value is maintained in the range of 5-6.

[0015] Preferably, in step (3): the concentration of the hyaluronic acid aqueous solution is 1-3% (w / v); the concentration of the 1-ethyl-(3-dimethylaminopropyl)carbodiimide aqueous solution is 0.5-1% (w / v); the concentration of the N-hydroxysuccinimide aqueous solution is 0.2-0.3% (w / v); and the concentration of 3-aminophenylboronic acid in the PBS buffer containing 3-aminophenylboronic acid is 1.5-2% (w / v).

[0016] Preferably, in step (3), the purification process includes: dialyzing with deionized water for 3 days (with a molecular weight cutoff of 3500 Da) and freeze drying.

[0017] Preferably, in step (4): the concentration of HA-PBA in the HA-PBA aqueous solution is 1-3% (w / v); the volume ratio of HA-PBA aqueous solution to PDA-CeO2 aqueous dispersion is 1:1; the crosslinking reaction conditions are: crosslinking reaction at room temperature for 20-50s; and the concentration of PDA-CeO2 nanocomposite material in pH-responsive antibacterial hydrogel is 125-1000μg / mL.

[0018] Preferably, a pH-responsive antibacterial hydrogel is prepared using the method described above.

[0019] Preferably, the application of a pH-responsive antibacterial hydrogel as described above in the preparation of a drug for treating burn wounds.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention integrates the photothermal antibacterial properties of PDA with the catalytic oxygen production / antioxidant function of CeO2 by coating cerium dioxide (CeO2) nanoparticles with polydopamine (PDA), successfully preparing a PDA-CeO2 nanocomposite material. This material is then introduced into a hydrogel system containing dynamic borate ester bonds. Utilizing an in-situ dynamic crosslinking method mediated by these dynamic borate ester bonds, HA-PBA and the PDA-CeO2 nanocomposite material are dynamically interacted and bonded to form a stable gel network structure. This structure exhibits pH responsiveness, sensitively responding to the unique slightly acidic environment (pH decrease) of burn-infected wounds, enabling the on-demand and precise release of therapeutic components such as the PDA-CeO2 nanocomposite material. Simultaneously, the dynamic borate ester bonds endow the hydrogel with excellent self-healing capabilities, restoring structural integrity after external force damage and extending the lifespan and barrier function of the dressing on dynamic wounds.

[0021] 2. In this invention, the PDA in the PDA-CeO2 nanocomposite material has a photothermal effect, which can generate local high heat under near-infrared laser irradiation, effectively destroying the bacterial biofilm structure and creating favorable conditions for subsequent antibacterial and immune clearance. At the same time, PDA can enhance the activity of CeO2's catalase-like enzyme (CAT) and superoxide dismutase (SOD) dual enzymes, amplifying the chemical regulation effect. CeO2 can alleviate wound hypoxia by catalyzing the decomposition of endogenous H2O2 to produce oxygen, and alleviate oxidative stress by clearing various types of reactive oxygen species (ROS), directly driving macrophages to polarize towards the M2 type to reshape the immune microenvironment. The improvement of immune imbalance can conversely reduce the excessive production of ROS and bacterial colonization, forming a positive feedback loop in the whole chain, and synergistically intervening in multiple pathological links such as burn wound infection, hypoxia, oxidative stress, and inflammatory imbalance.

[0022] 3. In this invention, the pH-responsive antibacterial hydrogel combines the high moisturizing properties of HA and the strong adhesive properties of PDA. It can maintain a moderately moist healing environment on the wound surface and has good plasticity, which can firmly adhere to irregular and moist burn wounds. It maintains structural stability through dynamic bond recombination, making it difficult to fall off and providing long-lasting protection. At the same time, it has environmental responsiveness and can realize intelligent controlled release of the loading material according to the wound microenvironment signals (such as pH value, reactive oxygen species level, etc.).

[0023] 4. In this invention, all raw materials (HA, chitosan, dopamine, etc.) have good biocompatibility and biodegradability. The preparation process is carried out in an aqueous phase without additional crosslinking agents and under mild conditions, which is conducive to the standardization and large-scale production of the product.

[0024] 5. Experiments show that the hydrogel prepared in this invention achieves highly efficient repair throughout the entire cycle, from infection control to tissue regeneration. Simultaneously, the hydrogel exhibits a maximum tensile stress of 120 kPa, high self-healing efficiency, and a degradation rate of approximately 20% after 20 days, closely matching the burn wound healing cycle. Under near-infrared irradiation, it achieves a >99% inhibition rate against drug-resistant bacteria and demonstrates excellent photothermal cycle stability. Therefore, the hydrogel prepared in this invention constructs a synergistic therapeutic system encompassing photothermal therapy, oxygen supply / antioxidation, and immune regulation. It provides synergistic intervention against multiple pathological aspects of burn wounds, including infection, hypoxia, oxidative stress, and inflammatory imbalance, demonstrating significantly better efficacy than single-function dressings and providing a multifunctional foundation for wound treatment. Attached Figure Description

[0025] Figure 1These are electron microscope (SEM) images, transmission electron microscope (TEM) images, and elemental distribution energy dispersive spectroscopy (EDS) images of the PDA-CeO2 nanocomposite material prepared in Example 1 of this invention; in the figures, (a) is the SEM image of the PDA-CeO2 nanocomposite material, (b) is the TEM image of the PDA-CeO2 nanocomposite material, and (c) is the EDS elemental distribution result of the PDA-CeO2 nanocomposite material; Figure 2 This is a UV-Vis DRS test result of the PDA-CeO2 nanocomposite material and CeO2 nanoparticles prepared in Example 1 of this invention; Figure 3 This is a graph showing the particle size distribution test results of the PDA-CeO2 nanocomposite material and CeO2 nanoparticles prepared in Example 1 of this invention; Figure 4 This is an X-ray photoelectron spectroscopy (XPS) spectrum of the PDA-CeO2 nanocomposite material prepared in Example 1 of this invention; in the figure, (a) is the high-resolution XPS spectrum of Ce, (b) is the high-resolution XPS spectrum of O, (c) is the high-resolution XPS spectrum of C, (d) is the high-resolution XPS spectrum of N, and (e) is the full XPS spectrum of PDA-CeO2. Figure 5 This is a schematic diagram of the preparation process for preparing PDA-CeO2@HA-PBA composite hydrogel in an embodiment of the present invention; Figure 6 These are electron microscope (SEM) images and energy dispersive spectroscopy (EDS) images of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention; in the figures, (a) is the SEM image of the PDA-CeO2@HA-PBA composite hydrogel, and (b) is the EDS image of the PDA-CeO2@HA-PBA composite hydrogel. Figure 7 The image shows the FTIR test results of the PDA-CeO2@HA-PBA composite hydrogel, PDA-CeO2 nanocomposite material, and CeO2 nanoparticles prepared in Example 1 of this invention. Figure 8 The tensile stress-strain curves of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention and the HA-PBA hydrogel prepared in Comparative Example 1 are shown. Figure 9 This is a rheological frequency scan of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention; Figure 10 This is a rheological strain scan of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention; Figure 11 This is a rheological self-healing cycle test diagram of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention; Figure 12 The swelling rate-time curves are shown for the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention and the HA-PBA hydrogel prepared in Comparative Example 1. Figure 13 The degradation rate-time curves of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention and the HA-PBA hydrogel prepared in Comparative Example 1 are shown. Figure 14 This is a graph showing the cumulative release rate of CeO2 under different pH conditions for the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention. Figure 15 These are temperature-time curves of the PDA-CeO2@HA-PBA composite hydrogels prepared in Examples 1-4 of this invention under 808nm near-infrared laser irradiation and a synchronous photothermal imaging image of Example 1; in the figures, (a) is the temperature-time curve of the PDA-CeO2@HA-PBA composite hydrogels prepared in Examples 1-4 under 808nm near-infrared laser irradiation, and (b) is the photothermal imaging image of the PDA-CeO2@HA-PBA composite hydrogels prepared in Examples 1-4 under 808nm near-infrared laser irradiation; Figure 16 This is a temperature-time curve of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of the present invention under irradiation with near-infrared laser power of 0W, 0.5W, 1.0W, 1.5W and 2.0W; Figure 17 This is a test diagram of the photothermal cycling stability of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention; Figure 18 This is a fitted curve of the photothermal conversion efficiency of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 of this invention; Figure 19 This is a plate colony count diagram of drug-resistant Staphylococcus aureus and drug-resistant Escherichia coli in the blank control group, P@HP(NIR+) group, C@HP(NIR+) group, PC@HP(NIR-) group, and PC@HP(NIR+) group in this invention; Figure 20 This is a statistical analysis chart of the colony-forming unit (CFU) count results of the blank control group, P@HP(NIR+) group, C@HP(NIR+) group, PC@HP(NIR-) group, and PC@HP(NIR+) group against drug-resistant Staphylococcus aureus and drug-resistant Escherichia coli in this invention. Figure 21 The figures show the healing effect and wound area analysis of the blank control group, P@HP group, C@HP group, PC@HP- group and PC@HP+ group in the mouse burn wound infection model in this invention; in the figure, (a) is the healing effect in the mouse burn wound infection model and (b) is the wound area analysis in the mouse burn wound infection model. Figure 22 This is a diagram showing the wound healing experimental results of the blank control group, P@HP group, C@HP group, PC@HP- group, and PC@HP+ group in a mouse burn wound infection model in this invention; Figure 23 These are the H&E staining images and Masson's trichrome staining images of wound tissues in a mouse burn wound infection model, including the blank control group, P@HP group, C@HP group, PC@HP- group, and PC@HP+ group. Figure 24 These are ELISA images of IL-4, IL-6, TGF-β, and TNF-α factors in wound tissues of the blank control group, P@HP group, C@HP group, PC@HP- group, and PC@HP+ group in a mouse burn wound infection model in this invention; in the figure, (a) is the ELISA image of IL-4 factor, (b) is the ELISA image of IL-6 factor, (c) is the ELISA image of TGF-β factor, and (d) is the ELISA image of TNF-α factor; Figure 25 These are H&E staining images of the main organs (heart, liver, spleen, lung, and kidney) in a mouse burn wound infection model, including the blank control group, P@HP group, C@HP group, PC@HP- group, and PC@HP+ group. Detailed Implementation

[0026] The present invention will be further illustrated below through specific embodiments. The following embodiments are specific implementations of the present invention, but the implementation of the present invention is not limited to the following embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

[0027] Example 1 This embodiment discloses a method for preparing a pH-responsive antibacterial hydrogel, comprising the following steps: Step (1) Preparation of CeO2 nanoparticles Ce(NO3)3·6H2O was dissolved in deionized water and magnetically stirred for 30 min until completely dissolved. Then, 1 mol / L NaOH aqueous solution was added to adjust the pH of the system to 10.0. Stirring was continued for 2 h to form a white precipitate. The mixture was transferred to a high-pressure reactor and reacted at 120℃ for 12 h. After the reaction was completed, the mixture was naturally cooled, and the precipitate was collected by centrifugation. After washing with water and ethanol alternately, the precipitate was dried under vacuum at 60℃ to obtain CeO2 nanoparticles. Among them, Ce(NO3)3 The ratio of 6H2O to deionized water is 1.72g:50mL; Step (2): Preparation of PDA-CeO2 nanocomposite material CeO2 nanoparticles were dispersed in deionized water and ultrasonically dispersed. Dopamine hydrochloride was added, and the pH of the system was adjusted to 8.0 with Tris-HCl buffer (pH=8.5). The reaction was stirred at room temperature in the dark for 18 h. After the reaction was completed, the product was collected by centrifugation, washed with water and ethanol alternately, and then freeze-dried to obtain PDA-CeO2 nanocomposite material. The ratio of CeO2 nanoparticles, deionized water, and dopamine hydrochloride was 0.1g:100mL:0.05g. Step (3) Preparation of HA-PBA HA was dissolved in deionized water and stirred continuously at 37°C for 2 hours until completely dissolved, yielding a 1% (w / v) HA aqueous solution. The pH was adjusted to 5.0 using 0.1 mol / L hydrogen chloride aqueous solution. EDC aqueous solution and NHS aqueous solution were added sequentially, followed by dropwise addition of 20 mL of PBS buffer (phosphate buffer, pH=7.0) containing 0.33 g 3-APBA. The reaction was carried out at 37°C under light-protected conditions with stirring for 48 hours, maintaining the pH in the range of 5-6. After the reaction was completed, the mixture was dialyzed with deionized water for 3 days (molecular weight cutoff of 3500 Da) and then freeze-dried to obtain HA-PBA. The mass ratio of HA, EDC, NHS, and 3-APBA is 100:58:29:165. Step (4): Preparation of PDA-CeO2@HA-PBA composite hydrogel HA-PBA was mixed with water to prepare a 2% (w / v) HA-PBA aqueous solution; PDA-CeO2 nanocomposite material was mixed with water to prepare a 1 mg / mL PDA-CeO2 aqueous dispersion. HA-PBA aqueous solution and PDA-CeO2 aqueous dispersion were mixed at a volume ratio of 1:1 and crosslinked at room temperature for 30 s. After the reaction was completed, PDA-CeO2@HA-PBA composite hydrogel with a PDA-CeO2 nanocomposite concentration of 500 μg / mL was obtained, which was denoted as PC@HP hydrogel, i.e. pH-responsive antibacterial hydrogel.

[0028] Example 2 The difference from Example 1 is that the concentration of PDA-CeO2 nanocomposite material in the PDA-CeO2@HA-PBA composite hydrogel prepared in step (3) is changed to 125 μg / mL; other parameters and conditions are the same as in Example 1.

[0029] Example 3 The difference from Example 1 is that the concentration of PDA-CeO2 nanocomposite material in the PDA-CeO2@HA-PBA composite hydrogel prepared in step (3) is changed to 250 μg / mL; other parameters and conditions are the same as in Example 1.

[0030] Example 4 The difference from Example 1 is that the concentration of PDA-CeO2 nanocomposite material in the PDA-CeO2@HA-PBA composite hydrogel prepared in step (3) is changed to 1000 μg / mL; other parameters and conditions are the same as in Example 1.

[0031] Comparative Example 1 The difference from Example 1 is that the 2% (w / v) HA-PBA aqueous solution in step (3) is not mixed with the PDA-CeO2 aqueous dispersion; other parameters and conditions are the same as in Example 1, and HA-PBA hydrogel without PDA-CeO2 nanocomposite material is obtained, which is denoted as HA-PBA.

[0032] Comparative Example 2 The difference from Example 1 is that the 1 mg / mL PDA-CeO2 aqueous dispersion in step (3) is replaced with a 1 mg / mL CeO2 nanoparticle aqueous dispersion; other parameters and conditions are the same as in Example 1, and a CeO2@HA-PBA composite hydrogel with a CeO2 nanoparticle concentration of 500 μg / mL is obtained, which is denoted as C@HP composite hydrogel.

[0033] Comparative Example 3 The difference from Example 1 is that the 1 mg / mL PDA-CeO2 aqueous dispersion in step (3) is changed to a 1 mg / mL PDA aqueous dispersion; other parameters and conditions are the same as in Example 1, and a PDA@HA-PBA composite hydrogel with a PDA concentration of 500 μg / mL is obtained, which is denoted as P@HP composite hydrogel.

[0034] In the above embodiments and comparative examples, all raw materials were commercially available.

[0035] Experimental Example 1 The size, structure, and properties of the PDA-CeO2 nanocomposite prepared in Example 1 were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental distribution energy dispersive spectroscopy (EDS), ultraviolet-visible spectrophotometry (UV-Vis), particle size distribution measurement, and X-ray photoelectron spectroscopy (XPS). The results are as follows: Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown.

[0036] Figure 1 SEM, TEM and elemental distribution spectra of PDA-CeO2 nanocomposite material. Figure 1 (a) in the image is a SEM image. Figure 1 (b) in the image is a TEM image, from... Figure 1 As can be seen from (a) and (b), the PDA-CeO2 nanocomposite material prepared by the present invention is uniformly spherical with an average diameter of about 50 nm and has good dispersibility; Figure 1 (c) in the figure shows the elemental distribution results of EDS, which confirms that Ce, O, C and N elements are uniformly distributed in PDA-CeO2 nanocomposite material, indicating that polydopamine (PDA) has been successfully coated on the CeO2 surface.

[0037] Figure 2 UV-Vis DRS test results for PDA-CeO2 nanocomposites and CeO2 nanoparticles: Compared with unmodified PDA CeO2, the PDA-CeO2 nanocomposites show significantly enhanced absorbance in the 300~700nm wavelength range, and exhibit absorbance at 298nm. -1 356nm -1 The characteristic absorption peak at the point corresponds to the π-π* transition of PDA, confirming that PDA has been successfully grafted onto the CeO2 surface.

[0038] Figure 3 The particle size distribution results of PDA-CeO2 nanocomposites and CeO2 nanoparticles are as follows: After PDA modification, the average particle size of the nanoparticles was adjusted from about 100 nm (CeO2 nanoparticles without PDA modification) to about 150 nm (PDA-CeO2 nanocomposites modified with PDA), further verifying the existence of the PDA coating layer. The particle size distribution of the PDA-CeO2 nanocomposites is more concentrated and the dispersion is improved.

[0039] Figure 4XPS analysis results of PDA-CeO2 nanocomposites: Characteristic peaks such as 882.4 eV and 898.2 eV in the Ce3d spectrum confirm that Ce³⁺... + / Ce 4+ The presence of redox pairs was confirmed; the peaks at 531.4 eV and 532.4 eV in the O1s spectrum correspond to the Ce-O bond and the CO bond in PDA; the peaks at 284.8 eV and 285.2 eV in the C1s spectrum correspond to the CC / C=C bond in PDA; the peak at 399.5 eV in the N1s spectrum corresponds to the amino functional group in PDA; the full spectrum scan results simultaneously contained Ce, O, C, and N elemental signals, consistent with the EDS results, confirming the successful recombination of PDA and CeO2.

[0040] In summary, the experimental results verify that a stable and structurally well-defined PDA-CeO2 nanocomposite material has been successfully prepared.

[0041] Experimental Example 2 The structure and nanoparticle loading of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 were characterized by scanning electron microscopy (SEM), elemental distribution energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The results are as follows: Figure 5 , Figure 6 , Figure 7 As shown.

[0042] Figure 5 The preparation process of the PDA-CeO2@HA-PBA composite hydrogel in the example is as follows: the HA-PBA solution and the PDA-CeO2 aqueous dispersion are mixed in a "one-pot method" to quickly form the PDA-CeO2@HA-PBA composite hydrogel. The hydrogel has the characteristic of dissolving on demand, which reflects its structural controllability.

[0043] Figure 6 SEM and elemental distribution maps of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1: The SEM images show that the PDA-CeO2@HA-PBA composite hydrogel has a three-dimensional porous structure with a pore size of approximately 200 μm, which is conducive to material transport; the EDS elemental distribution results show that C, O, N, B, and Ce elements are uniformly distributed in the hydrogel matrix, confirming that the PDA-CeO2 nanocomposite material has been successfully and uniformly loaded into the hydrogel.

[0044] Figure 7The FTIR test results for the PDA-CeO2@HA-PBA composite hydrogel, PDA-CeO2 nanocomposite material, and CeO2 nanoparticles prepared in Example 1 are shown. Compared with the PDA-CeO2 nanocomposite material and CeO2 nanoparticles that did not form a hydrogel, the PDA-CeO2@HA-PBA composite hydrogel showed a "BO" characteristic peak and a benzene ring characteristic peak in its spectrum, while retaining the characteristic signal of the Ce-O bond. This confirms that HA-PBA and PDA-CeO2 nanocomposite material were successfully crosslinked through borate ester bonds, and the hydrogel framework was completed.

[0045] In summary, the experimental results verify that the PDA-CeO2@HA-PBA composite hydrogel with controllable structure and uniform nanoparticle loading has been successfully prepared.

[0046] Experimental Example 3 The mechanical properties of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 were characterized by tensile and rheological tests, verifying its excellent mechanical strength and self-healing properties. The results are as follows: Figure 8 , Figure 9 , Figure 10 , Figure 11 As shown.

[0047] like Figure 8 As shown, the mechanical strength of the PDA-CeO2@HA-PBA composite hydrogel was verified by tensile stress-strain curves; the test method was as follows: the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 (i.e., Figure 8 PC@HP and HA-PBA hydrogel prepared in Comparative Example 1 (i.e., PC@HP) Figure 8 HA-PBA (HA-PBA hydrogel without PDA-CeO2 nanocomposite material) was used to prepare standard tensile specimens, and tensile tests were performed using a texture analyzer at a tensile speed of 5 mm / min. Figure 8 The results showed that the stress of the PDA-CeO2@HA-PBA composite hydrogel continued to increase with the increase of strain, and the maximum stress reached about 120 kPa, which was significantly higher than that of the HA-PBA hydrogel (maximum stress about 80 kPa). This confirmed that the introduction of PDA-CeO2 nanocomposite material effectively enhanced the mechanical strength of the hydrogel and could meet the mechanical requirements of wound dressing.

[0048] like Figure 9 , Figure 10 , Figure 11 As shown, the rheological properties of the PDA-CeO2@HA-PBA composite hydrogel were characterized by frequency scanning, strain scanning and self-healing cycle testing. The test conditions were as follows: a rheometer was used for testing, the plate diameter was 20 mm, the gap was 1 mm, and the temperature was 37℃.

[0049] Figure 9 It is a frequency scan diagram. Figure 9 As can be seen, under 1% strain (linear viscoelastic region), the storage modulus (G') of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 increases with increasing frequency, and G' is always higher than the loss modulus (G''), indicating that the PDA-CeO2@HA-PBA composite hydrogel has a stable elastic gel network structure.

[0050] Figure 10 It is a strain scan map. Figure 10 As can be seen, when the strain is below 100%, G' remains stable (approximately 10² Pa); when the strain increases to 10... 4 When the strain reaches %, G' decreases rapidly, indicating that the network structure can be reversibly dissociated; after strain recovery, G' can partially recover, reflecting the responsiveness of the dynamic network in the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1.

[0051] Figure 11 This is a self-healing cycle test diagram. Figure 11 As can be seen, when small strain of 1% (lasting 100s) and large strain of 1000% (lasting 100s) are applied alternately, the G' of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 can quickly recover to the initial level in the low strain stage, which confirms that the reversible recombination of dynamic bonds endows the hydrogel with excellent self-healing ability.

[0052] In summary, the experimental results verify that the PDA-CeO2@HA-PBA composite hydrogel in Example 1 of this invention possesses enhanced mechanical strength, a stable gel network, and efficient self-healing properties.

[0053] Test Example 4 The swelling and degradation behavior of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 was characterized by in vitro simulation experiments to verify that it possesses controllable swelling and degradation characteristics. The results were compared with those of the HA-PBA hydrogel prepared in Comparative Example 1. Figure 12 , Figure 13 As shown.

[0054] like Figure 12 As shown, the swelling behavior of PDA-CeO2@HA-PBA composite hydrogel and HA-PBA hydrogel was verified by swelling rate-time curves; Test method: The freeze-dried PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 (i.e., Figure 12 PC@HP and HA-PBA hydrogel prepared in Comparative Example 1 (i.e., PC@HP) Figure 12The HA-PBA hydrogel (containing PDA-CeO2 nanocomposite material) was placed in PBS buffer (pH 7.4) and incubated at 37°C. It was periodically removed and weighed to calculate the swelling rate (mass after swelling / initial lyophilized mass × 100%). Figure 12 The results showed that the swelling rate of the PDA-CeO2@HA-PBA composite hydrogel gradually increased over time, stabilizing after 15 days (approximately 60%); while the swelling rate of the HA-PBA hydrogel reached a plateau after 5 days (approximately 40%). This indicates that the introduction of the PDA-CeO2 nanocomposite material prolonged the swelling equilibrium time of the hydrogel and increased the final swelling rate, which is beneficial for maintaining moisture and releasing the loading material in the wound.

[0055] like Figure 13 As shown, the degradation behavior of PDA-CeO2@HA-PBA composite hydrogel and HA-PBA hydrogel was verified by degradation rate-time curves. Test method: The hydrogel samples were placed in PBS buffer (pH 7.4) containing hyaluronidase (10 U / mL) and incubated at 37℃. The samples were periodically taken out, lyophilized and weighed, and the degradation rate was calculated as ((initial mass - residual mass) / initial mass × 100%). Figure 13 The results showed that: PDA-CeO2@HA-PBA composite hydrogel (i.e. Figure 13 The degradation rate of PC@HP was significantly slower than that of HA-PBA hydrogel (i.e., Figure 12 After 20 days, the degradation rate of the PDA-CeO2@HA-PBA composite hydrogel was approximately 20%, while the degradation rate of the HA-PBA hydrogel reached 40%. This confirms that the interaction between the PDA-CeO2 nanocomposite material and the HA-PBA network delays enzymatic degradation, giving the hydrogel more durable structural stability and adapting it to the wound healing cycle.

[0056] In summary, the experimental results verify that the PDA-CeO2@HA-PBA composite hydrogel prepared in the embodiments of the present invention has controllable swelling behavior and long-term degradation stability.

[0057] Experimental Example 5 The responsive release behavior of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 was characterized by in vitro simulation experiments to verify its pH-responsive drug (CeO2) release capability.

[0058] like Figure 14As shown, the pH-responsive release performance of the PDA-CeO2@HA-PBA composite hydrogel was verified by the cumulative release rate-time curves under different pH conditions. Test method: The PDA-CeO2@HA-PBA composite hydrogel was placed in PBS buffer with pH values ​​of 5.0, 6.0 and 7.0, respectively, and incubated at 37℃. The concentration of CeO2 in the supernatant was measured periodically, and the cumulative release rate was calculated. Figure 14 The results showed that the hydrogel exhibited the highest cumulative CeO2 release rate in an acidic environment (pH 5.0), reaching approximately 70% after 20 days; in a weakly acidic environment (pH 6.0), the cumulative release rate was approximately 60%; and in a neutral environment (pH 7.0), the cumulative release rate was only approximately 45%. This difference stems from the reversible dissociation of borate ester bonds in the HA-PBA network under acidic conditions. Infected wound areas (typically with lower pH) can trigger hydrogel network relaxation, accelerating CeO2 release; while the release rate is slower in a normal physiological environment (pH 7.4), demonstrating the hydrogel's intelligent pH-responsive characteristics, which are adapted to the precise treatment needs of the wound microenvironment.

[0059] In summary, the experimental results verify that the PDA-CeO2@HA-PBA composite hydrogel has pH-responsive drug release capability, enabling intelligent drug release triggered by the wound microenvironment.

[0060] Experimental Example 6 The photothermal properties of the PDA-CeO2@HA-PBA composite hydrogels prepared in Examples 1-4 were characterized by temperature change curves, photothermal imaging, cycling stability testing, and photothermal conversion efficiency, verifying their excellent photothermal conversion capabilities. The results are as follows: Figure 15 , Figure 16 , Figure 17 , Figure 18 As shown.

[0061] like Figure 15 , Figure 16As shown, the photothermal heating capability of the PDA-CeO2@HA-PBA composite hydrogel was verified by temperature-time curves at different concentrations / powers. Experimental method: The PDA-CeO2@HA-PBA composite hydrogels prepared in Examples 1-4 (i.e., the PDA-CeO2@HA-PBA composite hydrogel with a concentration of 125 μg / mL prepared in Example 2, the PDA-CeO2@HA-PBA composite hydrogel with a concentration of 250 μg / mL prepared in Example 3, and the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1) were used. One mL each of the PDA-CeO2@HA-PBA composite hydrogel (with a composite material concentration of 500 μg / mL) and the PDA-CeO2 nanocomposite material prepared in Example 4 (with a concentration of 1000 μg / mL) were placed in a container and irradiated with an 808 nm near-infrared (NIR) laser, and the temperature change was recorded in real time. The temperature response of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 (with a composite material concentration of 500 μg / mL) was tested simultaneously at different laser powers (0.5, 1.0, 2.0 W).

[0062] from Figure 15 As can be seen from (a), the temperature of the hydrogels prepared in Examples 1-4 increased significantly with the increase of PDA-CeO2 nanocomposite concentration. The temperature of the 1000 μg / mL group rose to about 70 °C within 10 min of NIR irradiation, and the concentration was positively correlated with the temperature rise. Figure 15 (b) is a synchronous photothermal imaging image, which visually shows that the color of the hydrogel region gradually deepens as the irradiation time increases (corresponding to an increase in temperature), further verifying its photothermal conversion capability.

[0063] Figure 16 The results showed that when the laser power increased from 0.5W to 2.0W, the temperature of the PDA-CeO2@HA-PBA composite hydrogel with a concentration of 500μg / mL prepared in Example 1 increased from about 45℃ to about 70℃, confirming that the photothermal temperature rise was positively correlated with the laser power.

[0064] like Figure 17 As shown, the photothermal cycling stability of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 was verified by multiple "heating-cooling" cycle experiments. Experimental method: The PDA-CeO2@HA-PBA composite hydrogel (containing 500 μg / mL of PDA-CeO2 nanocomposite material) prepared in Example 1 was subjected to a "10 min heating → natural cooling to room temperature" cycle under 808 nm NIR laser irradiation, and the temperature change was recorded. Figure 17 The results showed that after three cycles, the hydrogel prepared in Example 1 could still rapidly heat up to about 60°C during the irradiation phase and stably cool down during the cooling phase, indicating that it has good photothermal cycling stability.

[0065] like Figure 18 As shown, the photothermal efficiency of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 was characterized by thermodynamic fitting experiments. Figure 18 The results show that the fitted curve exhibits a good linear relationship, and the fitting parameter τ s =265.68s, based on which the photothermal conversion efficiency η of the PDA-CeO2@HA-PBA composite hydrogel was calculated to be 46.66%. This efficiency is significantly higher than the typical level of traditional photothermal materials, confirming that the hydrogel can efficiently convert near-infrared light energy into heat energy, meeting the energy requirements of photothermal therapy.

[0066] In summary, the experimental results verify that the PDA-CeO2@HA-PBA composite hydrogel has a concentration / power controllable photothermal heating capability and excellent photothermal cycling stability and conversion efficiency.

[0067] Experimental Example 7 The antibacterial properties of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 were characterized by the minimum inhibitory concentration (MIC) test to verify its high antibacterial effect against drug-resistant bacteria (drug-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus). The results were compared with those of the blank control group, CeO2 nanoparticle group, PDA group, PDA+NIR group, PDA-CeO2 group, PC@HP+photothermal group, kanamycin group, and ampicillin group. The results are shown in Table 1.

[0068] Among them, drug-resistant Escherichia coli was purchased from the Henan Provincial Engineering Technology Research Center for Industrial Microbial Strains, strain number: BNCC336655, batch number: 240411; methicillin-resistant Staphylococcus aureus (i.e., drug-resistant Staphylococcus aureus) was purchased from the Henan Provincial Engineering Technology Research Center for Industrial Microbial Strains, strain number: BNCC186335, batch number: 250813.

[0069] Table 1

[0070] The minimum inhibitory concentration (MIC) test results in Table 1 show that the MICs of the blank control group, CeO2 nanoparticle treatment (CeO2 group), PDA treatment (PDA group), and PDA-CeO2 nanocomposite treatment (PDA-CeO2 group) against drug-resistant Staphylococcus aureus and drug-resistant Escherichia coli were all >128. When only PDA was combined with near-infrared (NIR) irradiation for 10 min (PDA+NIR group), the MIC decreased to 117 (drug-resistant Staphylococcus aureus) and 110 (drug-resistant Escherichia coli). When PDA-CeO2@HA-PBA composite hydrogel was combined with photothermal therapy (PC@HP+photothermal group, 808nm laser), the MIC further decreased to 59 (drug-resistant Staphylococcus aureus) and 56 (drug-resistant Escherichia coli), and the antibacterial activity was significantly better than that of traditional antibiotics (kanamycin group and ampicillin group).

[0071] The antibacterial properties of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 were characterized by colony forming unit (CFU) counting experiments to verify its highly effective antibacterial effect against drug-resistant bacteria. The results were compared with those of the blank control group, the P@HP(NIR+) group (PDA@HA-PBA composite hydrogel prepared in Comparative Example 3 combined with near-infrared irradiation for 10 min), the C@HP(NIR+) group (CeO2@HA-PBA composite hydrogel prepared in Comparative Example 2 combined with near-infrared irradiation for 10 min), the PC@HP(NIR-) group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1), and the PC@HP(NIR+) group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 combined with near-infrared irradiation for 10 min). Figure 19 and Figure 20 As shown.

[0072] Figure 19 and Figure 20 The CFU counting experiment results showed that the bacterial survival rate in the blank control group, P@HP(NIR+) group, and C@HP(NIR+) group was >70%; the survival rate in the PC@HP group without NIR irradiation (PC@HP(NIR-) group) decreased to 25% (drug-resistant Escherichia coli) and 35% (drug-resistant Staphylococcus aureus); while the bacterial survival rate in the PC@HP combined with NIR irradiation group (PC@HP(NIR+) group) was only about 0%, confirming that the synergistic effect of photothermal effect and PDA-CeO2 nanocomposite material can effectively inhibit the growth of drug-resistant bacteria. In summary, the experimental results verified that PDA-CeO2@HA-PBA composite hydrogel combined with near-infrared irradiation can achieve highly efficient inhibition of drug-resistant bacteria and has excellent antibacterial application potential.

[0073] Experimental Example 8 The healing properties of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 were characterized by healing tracking and histological staining experiments in a mouse burn wound infection model, verifying its excellent healing-promoting effect on burn wound infection.

[0074] The establishment of a mouse burn wound infection model includes the following steps: Mice were housed in a standard specific pathogen-free environment with constant temperature (22±1℃), constant humidity (50±5%), and a 12h diurnal rhythm, with free access to food and water. After one week of acclimatization, the skin on the back of the mice was shaved and disinfected. A full-thickness burn wound with a diameter of 1 cm was prepared in the center of the mouse's back using weights. Immediately afterwards, 100 μL of MRSA (methicillin-resistant Staphylococcus aureus) suspension (MRSA concentration 1×10⁻⁶) was inoculated. 6 CFU / mL (dispersion medium: physiological saline) was evenly applied to the wound surface to establish a burn infection wound model. Starting from the first day after successful modeling, each group of composite hydrogel materials was evenly applied to the surface of the infected wound daily, with a consistent application thickness. If there was residual hydrogel on the surface of the infected wound before each application, it was removed using medical tweezers. The daily application amount of composite hydrogel material was 1g for a full-thickness skin burn wound with a diameter of 1cm. Among them, the PC@HP+ group was immediately treated with an 808nm near-infrared laser (power density 1.0W / cm²) after coating. 2 The wound area was vertically irradiated for 5 minutes. During the irradiation, an infrared thermal imager was used to monitor and record the local temperature changes of the wound in real time to avoid secondary damage caused by excessive temperature. The other groups did not receive laser irradiation and were treated in a dark environment throughout the process.

[0075] The blank control group, P@HP group (PDA@HA-PBA composite hydrogel prepared in Comparative Example 3), C@HP group (CeO2@HA-PBA composite hydrogel prepared in Comparative Example 2), PC@HP- group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1), and PC@HP+ group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 combined with near-infrared irradiation for 10 min) were compared. The results are as follows: Figure 21 , Figure 22 , Figure 23 As shown.

[0076] Figure 21 and Figure 22The results of the wound healing experiment showed that in the mouse burn wound infection model, the wound healing rate of the blank control group, P@HP group and C@HP group was slow, and the wound area was still >40% on day 13; while the wound area of ​​the PC@HP- group (without NIR) decreased to about 20%, and the wound of the PC@HP+ group (with NIR) was basically completely closed on day 13. Quantitative analysis further confirmed that the wound area of ​​the PC@HP+ group decreased rapidly over time, which was significantly better than that of the control groups. The healing trajectory curve intuitively showed its rapid approach to complete closure.

[0077] Figure 23 Histological staining results showed that in H&E staining, the PC@HP+ group exhibited significantly reduced inflammatory cell infiltration and increased granulation tissue thickness. In Masson's trichrome staining, this group showed richer and more regularly arranged collagen deposition, while the blank control group and the P@HP group still showed a large number of inflammatory cells and sparse collagen deposition. In summary, the experimental results validate that PC@HP hydrogel (especially when combined with NIR) can achieve efficient wound healing of burns through the synergistic effect of photothermal and material properties, clearing pathogens, regulating the wound microenvironment, and promoting tissue regeneration, demonstrating excellent potential for wound treatment.

[0078] Experimental Example 9 The anti-inflammatory properties of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 were verified by ELISA detection of wound tissue from a mouse burn wound infection model, confirming its excellent anti-inflammatory and immunomodulatory capabilities. The blank control group, P@HP group (PDA@HA-PBA composite hydrogel prepared in Comparative Example 3), C@HP group (CeO2@HA-PBA composite hydrogel prepared in Comparative Example 2), PC@HP- group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1), and PC@HP+ group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 combined with near-infrared irradiation for 10 min) were compared, and the results are as follows: Figure 24 As shown.

[0079] Figure 24 The results of pro-inflammatory factor detection showed that the levels of IL-4 and IL-6 in the blank control group were significantly higher, while the IL-4 level in the PC@HP+ group (combined with NIR) was significantly increased (approximately 5 times higher than that in the blank control group), and the IL-6 level decreased from approximately 100 mg / mL in the blank control group to approximately 30 mg / mL, confirming that hydrogel can effectively regulate the expression of pro-inflammatory factors. At the same time, the level of the pro-inflammatory factor TNF-α in the PC@HP+ group decreased from approximately 50 mg / mL in the blank control group to less than 10 mg / mL, showing a significant anti-inflammatory effect.

[0080] Figure 24The results of the detection of healing-promoting factors showed that the TGF-β level in the PC@HP+ group was approximately 1.5 times higher than that in the blank control group, indicating that the hydrogel can simultaneously promote the secretion of healing-promoting factors. In summary, the experimental results validate that PC@HP hydrogel (especially when combined with NIR) can effectively reduce the inflammatory response and synergistically promote tissue regeneration by inhibiting pro-inflammatory factors (IL-6, TNF-α) and upregulating anti-inflammatory / healing-promoting factors (IL-4, TGF-β), thus providing immunomodulatory support for burn wound healing.

[0081] Experimental Example 10 The biosafety of the PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 was characterized by histological staining of major organs in a mouse burn wound infection model, verifying its good in vivo biosafety. The blank control group, P@HP group (PDA@HA-PBA composite hydrogel prepared in Comparative Example 3), C@HP group (CeO2@HA-PBA composite hydrogel prepared in Comparative Example 2), PC@HP- group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1), and PC@HP+ group (PDA-CeO2@HA-PBA composite hydrogel prepared in Example 1 combined with near-infrared irradiation for 10 min) were compared, and the results are as follows: Figure 25 As shown.

[0082] Figure 25 In the study, histological analysis of major organs showed that: H&E staining of the heart, liver, spleen, lungs, and kidneys of mice in the blank control group, P@HP group, C@HP group, PC@HP- group (without NIR), and PC@HP+ group (with NIR) revealed that the histological morphology of the organs in each experimental group was consistent with that in the blank control group: the myocardial fibers of the heart were arranged regularly without degeneration or necrosis; the hepatocytes of the liver were intact without inflammatory infiltration; the lymphoid follicles of the spleen were clearly defined without abnormal proliferation; the alveolar structures of the lungs were normal without edema or exudation; and the glomeruli and renal tubules of the kidneys were intact without pathological damage.

[0083] In summary, the experimental results verify that the PDA-CeO2@HA-PBA composite hydrogel (including combined NIR treatment) has no significant toxic damage to the major organs of mice and has good in vivo biosafety, providing safety support for its clinical application.

[0084] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a pH-responsive antibacterial hydrogel, characterized in that, Includes the following steps: Step (1): Disperse CeO2 nanoparticles in water, add dopamine hydrochloride, react, and after the reaction is completed, purify to obtain PDA-CeO2 nanocomposite material and prepare PDA-CeO2 aqueous dispersion. Step (2): Adjust the pH of the hyaluronic acid aqueous solution to 5-6, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide aqueous solution and N-hydroxysuccinimide aqueous solution in sequence, add PBS buffer containing 3-aminophenylboronic acid dropwise, react, and after the reaction is completed, purify to obtain HA-PBA, and prepare HA-PBA aqueous solution. A pH-responsive antibacterial hydrogel was obtained by mixing and crosslinking HA-PBA aqueous solution with PDA-CeO2 aqueous dispersion.

2. The method for preparing a pH-responsive antibacterial hydrogel according to claim 1, characterized in that, In step (1), the CeO2 nanoparticles are prepared by the following steps: Ce(NO3)3·6H2O was dissolved in water and stirred until completely dissolved. After the reaction was completed, the mixture was purified to obtain CeO2 nanoparticles.

3. The method for preparing a pH-responsive antibacterial hydrogel according to claim 2, characterized in that, In step (1), when preparing CeO2 nanoparticles: Ce(NO3)3 The mass ratio of 6H2O to water is (1.70-1.75):(45-55); the reaction conditions are: adjust the pH of the system to 9.0-11.0, continue stirring for 2-3 hours to form a white precipitate, and react the mixture at 110-130℃ for 10-12 hours.

4. The method for preparing a pH-responsive antibacterial hydrogel according to claim 1, characterized in that, In step (1), the mass ratio of CeO2 nanoparticles, water, and dopamine hydrochloride is (0.1-0.2):(100-120):(0.04-0.08); the reaction conditions are: adjust the pH of the system to 8.0-8.5 with Tris-HCl buffer, and stir the reaction at room temperature in the dark for 16-20 hours.

5. The method for preparing a pH-responsive antibacterial hydrogel according to claim 1, characterized in that, In step (2), when preparing HA-PBA, the reaction conditions are as follows: under light-protected conditions, the reaction is stirred at 35-38℃ for 45-50 hours, and the pH value is maintained in the range of 5-6.

6. The method for preparing a pH-responsive antibacterial hydrogel according to claim 1, characterized in that, In step (2), when preparing HA-PBA: the concentration of the hyaluronic acid aqueous solution is 1-3% w / v; the concentration of the 1-ethyl-(3-dimethylaminopropyl)carbodiimide aqueous solution is 0.5-1% w / v; the concentration of the N-hydroxysuccinimide aqueous solution is 0.2-0.3% w / v; and the concentration of 3-aminophenylboronic acid in the PBS buffer containing 3-aminophenylboronic acid is 1.5-2% w / v.

7. The method for preparing a pH-responsive antibacterial hydrogel according to claim 1, characterized in that, In step (2), when preparing the pH-responsive antibacterial hydrogel: the concentration of HA-PBA in the HA-PBA aqueous solution is 1-3% w / v; the volume ratio of HA-PBA aqueous solution to PDA-CeO2 aqueous dispersion is 1:

1.

8. The method for preparing a pH-responsive antibacterial hydrogel according to claim 1, characterized in that, In step (2), when preparing the pH-responsive antibacterial hydrogel, the crosslinking reaction conditions are: crosslinking reaction at room temperature for 20-50 seconds; The concentration of PDA-CeO2 nanocomposite material in pH-responsive antibacterial hydrogels is 125-1000 μg / mL.

9. A pH-responsive antibacterial hydrogel prepared by the method described in any one of claims 1-8.

10. The use of the pH-responsive antibacterial hydrogel as described in claim 9 in the preparation of a drug for treating burn wounds.

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