Antibacterial and immunoregulation hydrogel as well as preparation method and application thereof

Abstract

The invention is applicable to the field of new biomedical materials, and provides an antibacterial and immunoregulation hydrogel and a preparation method and application thereof, the hydrogel comprises oDex, EPL, TA and Fe < 3 + >, and three hydrogels with antibacterial, antioxidant, anti-inflammatory and immunoregulation functions can be obtained based on Schiff base bonds of oDex and EPL, ionic bonds and hydrogen bonds of TA and EPL and coordination of TA and Fe < 3 + >. The hydrogel has the advantages of being easy to operate, low in price and the like. The hydrogel has a photothermal therapy (PTT) combined EPL and TA / Fe < 3 + > compound sterilization function. The hydrogel has high adhesion, can effectively inhibit release of oxidative stress (RONS) and inflammatory factors by releasing TA, promotes polarization of macrophages from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and can effectively promote healing of mouse diabetic bacterial infected wounds.

Description

Technical Field

[0001] The present invention relates to the field of new biomedical materials, and in particular to an antibacterial and immune-regulating hydrogel, and a preparation method and application thereof. Background Art

[0002] Chronic diabetic wounds are a common complication of diabetes. Normal wound healing typically proceeds through four phases: hemostasis, inflammation, proliferation, and remodeling. However, diabetic wounds heal slowly due to pathological causes such as bacterial infection, oxidative stress, pathological inflammatory responses, and immune cell dysregulation (see T. Xiang, Q. Guo, L. Jia, T. Yin, W. Huang, X. Zhang, S. Zhou, Advanced healthcare materials. 2024, 13, 2301885.). Based on these mechanisms, effective treatment of diabetic wounds requires a multi-target synergistic strategy: bacterial clearance, regulation of oxidative stress, inhibition of inflammatory responses, regulation of macrophage polarization, and promotion of proliferation are key to effective treatment of diabetic wounds.

[0003] In recent years, hydrogels have been widely used in diabetic wound dressings due to their drug delivery capabilities, hydrophilicity, and high biocompatibility (see BH Shan, FG Wu, Advanced Materials. 2024, 36, 2210707). Hydrogels have a structure similar to that of tissue extracellular matrix, making them adaptable to irregular wound sites, absorbing wound tissue exudate and effectively maintaining wound moisture, thereby promoting tissue repair and regeneration. However, many hydrogel strategies tend to only address one aspect of the multiple wound healing processes, rarely addressing every aspect of the healing process (see Y. Tang, H. Xu, X. Wang, S. Dong, L. Guo, S. Zhang, X. Yang, C. Liu, X. Jiang, M. Kan, Journal of Nanobiotechnology. 2023, 21, 300). Therefore, the development of multifunctional hydrogel dressings for treating diabetic infected wounds is urgently needed. Summary of the Invention

[0004] The present invention provides an antibacterial and immunomodulatory hydrogel and a preparation method and application thereof, in order to solve the technical problems mentioned in the background technology.

[0005] An antibacterial and immune-regulating hydrogel comprising oxidized dextran (oDex), ε-polylysine (EPL), tannic acid (TA) and ferric chloride (Fe 3+), based on the Schiff base bond between oDex and EPL, the ionic bond and hydrogen bond between TA and EPL, and the bond between TA and Fe 3+ The coordination effect of the three hydrogels (OETF) with photothermal assisted antibacterial, antioxidant, anti-inflammatory and immune regulation functions can be obtained. n ); wherein, oDex is obtained by oxidizing dextran through NaIO4.

[0006] Furthermore, the oDex is prepared by oxidizing dextran (Dex) with sodium periodate (NaIO4); the molecular weight of the dextran is 20,000~70,000 Da, more preferably 70,000 Da; the mass ratio of the NaIO4 to dextran is 0.64~1.28:1, more preferably 0.96:1.

[0007] Furthermore, the preparation steps of oDex are as follows: 2 g of Dex with molecular weights of 20,000, 40,000, and 70,000 Da were dissolved in 20 mL of deionized water; Dissolve 1.28-2.56 g NaIO4 in 12-24 mL deionized water, preferably 18 mL; The NaIO4 solution was added dropwise to the Dex solution, and the mixture was stirred at room temperature for 1 to 4 h, more preferably 4 h. Then, 1 mL of ethylene glycol was added dropwise to terminate the reaction. The mixture was dialyzed in deionized water and freeze-dried to prepare oDex.

[0008] Another object of the present invention is to provide a method for preparing an antibacterial and immunomodulatory hydrogel, the method comprising the following steps: S1. Dissolve oDex, EPL, TA, and FeCl3·6H2O in phosphate buffer (pH 7.4). S2, stir and mix oDex, EPL and TA, and add FeCl3·6H2O solution; S3. Add 1 M NaOH dropwise to the solution obtained in step S2 at 37° C. to prepare the hydrogel.

[0009] Furthermore, the oDex concentration is 1-7 w / v%, more preferably 7 w / v%; the EPL molecular weight is 2,000-5,000 Da, more preferably 5,000 Da; the EPL concentration is 1-4 w / v%, more preferably 4 w / v%; the TA concentration is 0-1 w / v%, more preferably 0 w / v% (OE), 0.5 w / v% (OETF5) and 1 w / v% (OETF 10 );Fe 3+The concentration is 0-0.3 w / v%, more preferably 0.15 w / v%; the amount of 1 M NaOH added is 0-20 μL, more preferably 15 μL (OETF5) and 20 μL (OETF 10 ), and finally three hydrogels were obtained, which were named OE, OETF5 and OETF according to the TA concentration. 10 .

[0010] Another object of the present invention is to provide an application of the antibacterial and immunomodulatory hydrogel as described above in the preparation of medical antibacterial repair materials.

[0011] Beneficial effects achieved by the present invention: The hydrogel of the present invention is bonded by the Schiff base bond between oDex and EPL, the ionic bond and hydrogen bond between TA and EPL, and the bond between TA and Fe. 3+ It is prepared by the coordination effect of EPL and TA, and exerts antibacterial effect by releasing EPL and TA in combination with photothermal therapy (PTT); secondly, the hydrogel clears excessive RONS at the infected site by releasing TA, which can reduce the level of oxidative stress at the infected site and reduce the production of inflammatory factors; in addition, the hydrogel regulates the phenotypic polarization of macrophages, balances the M1 / M2 cell levels, promotes cell proliferation, and effectively treats wound healing caused by diabetic bacterial infection. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 3 is a scanning electron microscope image of the hydrogel obtained in the example of the present invention.

[0013] Figure 2 This is a diagram showing the antibacterial results of the flat-plate coating of the hydrogel obtained in an example of the present invention.

[0014] Figure 3 This is a diagram showing the cytotoxicity results of the hydrogel obtained in the examples of the present invention.

[0015] Figure 4 Graph showing the antioxidant and anti-inflammatory effects of the hydrogels obtained in the examples of the present invention.

[0016] Figure 5 This is a flow cytometry result diagram of the hydrogel obtained in an example of the present invention regulating the polarization of macrophages M1 and M2.

[0017] Figure 6 This is a graph showing the results of the hydrogel obtained in an example of the present invention promoting the wound healing rate. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The present invention provides an antibacterial and immune regulating hydrogel, which comprises oDex (dextrose obtained by oxidation of NaIO4), EPL, TA and Fe 3+ , based on the Schiff base bond between oDex and EPL, the ionic bond and hydrogen bond between TA and EPL, and the 3+ Coordination synthesis.

[0020] The oDex preparation method includes the following steps: dissolving 2 g of Dex with a molecular weight of 20,000-70,000 Da in 20 mL of deionized water; dissolving 1.28-2.56 g of NaIO4 in 12-24 mL of deionized water; adding the NaIO4 solution dropwise to the Dex solution, stirring at room temperature for 1-4 hours, then adding 1 mL of ethylene glycol dropwise to terminate the reaction, dialyzing in deionized water, and freeze-drying to prepare oDex.

[0021] During the oDex preparation process, the molecular weight of Dex is preferably between 20,000 and 70,000 Da, more preferably 70,000 Da; the mass ratio of NaIO4 to Dex is between 0.64 and 1.28:1, more preferably 0.96:1; the volume of deionized water is between 12 and 24 mL, more preferably 18 mL; and the reaction time is preferably between 1 and 4 hours, more preferably 4 hours. The oDex is then dialyzed in deionized water and lyophilized to prepare it.

[0022] The hydrogel comprises the following preparation steps: S1. Dissolve oDex, EPL, TA, and FeCl3·6H2O in phosphate buffer (pH 7.4). S2, stir and mix oDex, EPL and TA, and add FeCl3·6H2O solution; S3. Add 1 M NaOH dropwise to the solution obtained in step S2 at 37° C. to prepare the hydrogel.

[0023] According to the present invention, during the preparation of the hydrogel, the oDex concentration is preferably 1-7 w / v%, more preferably 7 w / v%. The EPL molecular weight is preferably 2,000-5,000 Da, more preferably 5,000 Da. The EPL concentration is preferably 1-4 w / v%, more preferably 4 w / v%. The TA concentration is preferably 0-1 w / v%, more preferably 0 w / v% (OE), 0.5 w / v% (OETF5), and 1 w / v% (OETF). 10 ). Fe 3+ The concentration is preferably 0-0.3 w / v%, more preferably 0.15 w / v%. The amount of 1 M NaOH added is preferably 0-20 µL, more preferably 15 µL (OETF5) and 20 µL (OETF 10 ), and finally three hydrogels were obtained, which were named OE, OETF5 and OETF according to the TA concentration. 10 .

[0024] According to the present invention, the hydrogel photothermal assisted antibacterial function, the near-infrared laser wavelength is preferably 808 nm. The near-infrared laser power is preferably 0.5~1.5 W / cm 2 , more preferably 1 W / cm 2 The near-infrared laser working time is preferably 1 to 10 minutes, more preferably 5 minutes.

[0025] In an embodiment of the present invention, the following is performed: 1) Antibacterial experiment: In the present invention, Escherichia coli (marked in the result diagram) was selected. E. coli ), Staphylococcus aureus (marked in the result figure S. aureus ) and methicillin-resistant Staphylococcus aureus (marked in the results MRSA ) To study the antibacterial activity of the hydrogel, it is preferred to culture the bacteria in LB medium; preferably, the concentration of the bacterial solution is 1 × 10 6 ~1 × 10 8 cfu / mL, more preferably 1 × 10 8 cfu / mL; the co-culture time of the hydrogel and the bacterial solution is preferably 0.5-4 h, more preferably 0.5 h; the hydrogel is preferably irradiated with an 808 nm near-infrared laser, and the power is preferably 0.5-1.5 W / cm 2 , more preferably 1 W / cm 2The irradiation time is preferably 1 to 10 min, more preferably 5 min. The antibacterial ability of the hydrogel is preferably studied by the plate count method, and the bacterial solution dilution factor is preferably 100 to 10,000 times, more preferably 10,000 times. The volume of the bacterial solution coated on the plate is preferably 30 to 50 μL, more preferably 30 μL. The culture conditions are preferably 37°C for 16 to 20 h, and the colony growth is observed and recorded to evaluate the antibacterial activity of the hydrogel.

[0026] 2) Cell culture: In the present invention, the RAW 264.7 cell line is selected and the cells are preferably cultured in DMEM medium containing 10% fetal bovine serum. The culture conditions are preferably carried out in an incubator with a volume fraction of 5% carbon dioxide and the culture temperature is preferably 37°C.

[0027] 3) Cytotoxicity: In the present invention, L929 cell line was selected for cytotoxicity evaluation. The L929 cell density was 5×10 3 Cells were seeded / well in a 96-well plate and cultured overnight. The hydrogel extract was added to the plate and incubated with the cells for 24 and 72 hours. The hydrogel extract was then washed with PBS and fresh culture medium was added. Finally, 20 μL of MTT solution was added to each well. After an additional 4 hours of incubation, 150 μL of DMSO was added to each well. The plate was gently shaken and the absorbance of each well was measured at 492 nm using a microplate reader. Cell viability was calculated using the following formula.

[0028] Cell viability (%) = (A sample / A blank) × 100; 4) Anti-inflammatory and antioxidant treatment at the cellular level: In the present invention, RAW 264.7 cell line is preferred for anti-inflammatory and antioxidant treatment at the cellular level (DCFH-DA fluorescent probe is used to detect the level of intracellular reactive oxygen species). The RAW 264.7 cell line is cultured at a density of 1×10 4 Cells were seeded / well in a 96-well plate and cultured overnight. The model and hydrogel-treated groups were incubated with lipopolysaccharide (LPS) at concentrations of 1–5 μg / mL for 6–24 hours. The LPS concentration was preferably 1 μg / mL, and the stimulation time was preferably 24 hours.

[0029] 5) Regulation of M1 / M2 polarization at the cellular level: In the present invention, the RAW 264.7 cell line is preferably used for regulation of M1 / M2 polarization at the cellular level. The RAW 264.7 cell line is cultured at a density of 1×10 5Macrophages were seeded / well in a 24-well plate and cultured overnight. The model group and hydrogel-treated group were incubated with lipopolysaccharide (LPS) at concentrations of 1 to 5 μg / mL for 6 to 24 hours, respectively. The LPS concentration was preferably 1 μg / mL, and the stimulation time was preferably 24 hours. The expression levels of the M1 marker CD86 and the M2 marker CD206 were measured by flow cytometry to evaluate the hydrogel's regulatory effect on macrophage M1 / M2 polarization.

[0030] 6) Animal Model: In the present invention, male C57 BL / 6 mice were used for the experiment. Streptozotocin (STZ) was used to induce the diabetic model. The STZ concentration was preferably 150-200 mg / kg, more preferably 180 mg / kg. Staphylococcus aureus was used to induce the diabetic local wound infection model. The concentration of Staphylococcus aureus was preferably 1 × 10 5 ~1 × 10 8 cfu / mL, more preferably 1 × 10 8 cfu / mL, the volume of the bacterial solution is preferably 10-40 μL, more preferably 40 μL. After inoculating the bacterial solution, the drug treatment experiments for different groups are started.

[0031] In order to facilitate those skilled in the art to better understand the technical solutions of the present invention, specific embodiments of the present invention are given as follows: The reagents used in the following examples are all commercially available products.

[0032] Examples 1 to 36 The present invention provides a method for preparing an antibacterial and immunomodulatory hydrogel, the method comprising the following steps: oDex includes the following preparation steps: 2 g of Dex with a molecular weight of 70,000 Da is dissolved in 20 mL of deionized water; 1.92 g of NaIO4 is dissolved in 18 mL of deionized water; the NaIO4 solution is added dropwise to the Dex solution, stirred at room temperature for 4 hours, and then 1 mL of ethylene glycol is added dropwise to terminate the reaction. The oDex is dialyzed in deionized water and freeze-dried to prepare oDex.

[0033] oDex, EPL, TA, and FeCl3·6H2O were dissolved in phosphate buffer (pH 7.4), respectively. oDex, EPL, and TA were stirred and mixed, and FeCl3·6H2O solution was added. 1 M NaOH was added dropwise to the above solution at 37°C to prepare the hydrogel.

[0034] During the hydrogel preparation process, oDex with a concentration of preferably 1-7 w / v %, EPL with a molecular weight of preferably 5,000 Da and a concentration of preferably 1-4 w / v %, TA with a concentration of preferably 0-1 w / v %, and Fe with a concentration of preferably 0-0.15 w / v % are added. 3+ Mix well and add preferably 0~20 μL of 1 M NaOH to finally obtain three hydrogels, which are named OE, OETF5 and OETF according to the TA concentration. 10 Among them, oDex, EPL, TA, Fe 3+ The amounts of NaOH used are shown in Table 1.

[0035] Table 1 Amounts of different raw materials in Examples 1 to 36

[0036] The hydrogels prepared in Examples 12, 24, and 36 were analyzed using a scanning electron microscope to obtain scanning electron microscope images, which were named OE, OETF5, and OETF according to the TA concentration. 10 . Figure 1 The scanning electron microscopy images of the hydrogels prepared in Examples 12, 24 and 36 are as follows. Figure 1 As shown, the results indicate that the hydrogels prepared in Examples 12, 24 and 36 all have interconnected porous microstructures, and the pore size of the hydrogels decreases with increasing TA concentration.

[0037] Experimental Example 1 For the PBS control group and Met-treated group, the concentration of 1×10 8 cfu / mL of Escherichia coli (marked in the result figure E. coli ), Staphylococcus aureus (marked in the result figure S. aureus ) and methicillin-resistant Staphylococcus aureus (marked in the results MRSA ) (100 μL) were incubated with PBS and methicillin (Met) with a final concentration of 128 μg / mL for 0.5 h; for the hydrogel treatment group, 100 μL of bacterial solution was added dropwise to OE, OETF5 and OETF 10 Co-cultured on the hydrogel surface for 0.5 h, OETF 10 The power used in the +NIR treatment group was 1 W / cm 2 808 nm near-infrared laser irradiation of OETF 10 After 5 min of hydrogel incubation, the cells were incubated for another 0.5 h. The bacterial solution was diluted 10,000 times with sterile PBS. The antibacterial ability of the hydrogel was studied by plate count method. 30 μL of the diluted bacterial solution was plated and incubated at 37 °C for 20 h. Figure 2 As shown, the results showed that compared with the PBS control group ( Figure 2 Compared with the control group (named as Control in Figure 2), the Met treatment group (named as Met in Figure 2) had a weaker antibacterial effect in a short period of time; while OE, OETF5 and OETF 10 Hydrogel treatment group ( Figure 2 They are named OE, OETF5 and OETF respectively. 10 ) has effective antibacterial activity, and the antibacterial activity increases with the increase of TA concentration; OETF 10 +NIR treatment group ( Figure 2 OETF 10 +NIR), OETF after 808 nm near-infrared laser irradiation 10 The hydrogel can kill more than 90% of bacteria.

[0038] Experimental Example 2 The L929 cell density was 5×10 3 / well were planted in a 96-well plate and cultured overnight. DMEM culture medium was used as a negative control. The hydrogel extract was added to the well plate and incubated with cells for 24 h and 72 h. Then the hydrogel extract was washed with PBS and fresh culture medium was added. Finally, 20 μL of MTT solution was added to each well. After incubation for another 4 h, 150 μL of DMSO was added to each well and the well plate was gently shaken. The absorbance value of each well was detected by a microplate reader at 492 nm. Cytotoxicity was calculated according to Formula 1. Figure 3 As shown, the results showed that compared with the control group ( Figure 3 Compared with OE, OETF5 and OETF 10 ( Figure 3 They are named OE, OETF5 and OETF respectively. 10 ) hydrogels have good biocompatibility.

[0039] Formula 1: Cell viability (%) = (absorbance of treatment group / absorbance of control group) × 100%; Experimental Example 3 The density of RAW 264.7 cells was 1×10 4 The cells were seeded in 96-well plates and cultured overnight. The LPS model group was incubated with 1 μg / mL LPS and RAW 264.7 cells for 24 h, and the hydrogel treatment group was treated with OE, OETF5 and OETF. 10 RAW 264.7 cells were co-treated with 1 μg / mL LPS for 24 h. Figure 4 As shown in A, the results showed that compared with the normal cell control group ( Figure 4 Compared with the LPS model group ( Figure 4The oxidative stress level (DCFH-DA fluorescence intensity) of the OE, OETF5 and OETF group was significantly increased compared with the LPS model group. 10 Hydrogel treatment group ( Figure 4 They are named OE, OETF5 and OETF respectively. 10 ) significantly reduced the oxidative stress level (DCFH-DA fluorescence intensity). Figure 4 As shown in BD, the results showed that compared with the normal cell control group ( Figure 4 Compared with the LPS model group (named Control), the levels of pro-inflammatory cytokines in the LPS model group were significantly increased; compared with the LPS model group ( Figure 4 Compared with OE, OETF5 and OETF 10 Hydrogel treatment group ( Figure 4 They are named OE, OETF5 and OETF respectively. 10 The levels of pro-inflammatory factors TNF-α, IL-6, and IL-1β in the cell supernatant of the hydrogel were significantly reduced, and the anti-inflammatory and antioxidant activities of the hydrogel were enhanced with the increase of TA concentration in the hydrogel.

[0040] Experimental Example 4 The density of RAW 264.7 cells was 1×10 5 The cells were seeded in 24-well plates and cultured overnight. The LPS model group was incubated with 1 μg / mL LPS and RAW 264.7 cells for 24 h, and the hydrogel treatment group was treated with OE, OETF5 and OETF. 10 RAW 264.7 cells were co-treated with the hydrogel extract and 1 μg / mL LPS for 24 h. The expression levels of M1 marker CD86 and M2 marker CD206 were detected by flow cytometry to evaluate the regulatory function of the hydrogel on macrophage M1 / M2 polarization. Figure 5 As shown, the results showed that compared with the normal cell control group ( Figure 5 Compared with the LPS model group ( Figure 5 The expression level of CD86 in the model group was significantly increased, and the expression level of CD206 was decreased, indicating that M1 polarization was significant. Compared with the LPS model group, OE, OETF5 and OETF 10 Hydrogel treatment group ( Figure 5 They are named OE, OETF5 and OETF respectively. 10 ) The expression of M1 marker CD86 decreased, and the expression of M2 marker CD206 increased, indicating that the hydrogel has effective immune regulatory function, and the immune regulatory ability of the hydrogel is enhanced with the increase of TA concentration.

[0041] Experimental Example 5 The diabetic model was induced by intraperitoneal injection of 180 mg / kg STZ in male C57 BL / 6 mice. A circular wound with a diameter of 8 mm was created on the back of the mice, and 40 μL of 1 × 10 8 A diabetic local wound infection model was established using Staphylococcus aureus at cfu / mL. After inoculation with the bacterial solution, drug treatment experiments were performed on different hydrogel groups. PBS was used as the negative control group ( Figure 6 The commercially available Tegaderm membrane was used as a positive control group ( Figure 6 named Tegaderm in the United States), using OE and OETF 10 Hydrogel as the treatment group ( Figure 6 Named OE and OETF respectively 10 ), the administration method is to drip PBS onto the wound surface; Tegaderm membrane is used to seal the wound; different hydrogels are applied to the wound surface, and the administration is carried out every two days and the wound area is recorded. Figure 6 As shown, the results showed that compared with the negative control group ( Figure 6 Compared with the positive control group ( Figure 6 The therapeutic effect of OE and OETF is weak and cannot promote wound healing. 10 Treatment group ( Figure 6 Named OE and OETF respectively 10 ) can effectively promote the healing of diabetic infected wounds. The healing speed is accelerated with the increase of TA concentration. Under the assistance of photothermal therapy, the power of 1 W / cm 2 Irradiation of OETF with 808 nm near-infrared light 10 Hydrogel was used as OETF for 5 min 10 +NIR treatment group, OETF 10 +NIR treatment group ( Figure 6 OETF 10 +NIR) The wounds were almost completely healed after 14 days of treatment.

[0042] The hydrogel provided by the present invention has antibacterial, antioxidant, anti-inflammatory and immune regulation functions, and the hydrogel has the advantages of easy operation and low price. The hydrogel is bonded by the Schiff base bond between oDex and EPL, the ionic bond and hydrogen bond between TA and EPL, and the TA and Fe 3+The hydrogel is prepared by the coordination effect of EPL and TA; the hydrogel exerts antibacterial effect by releasing EPL and TA in combination with photothermal therapy (PTT); the hydrogel clears excessive RONS at the infected site by releasing TA, which can reduce the level of oxidative stress at the infected site and reduce the production of inflammatory factors; the hydrogel regulates the phenotypic polarization of macrophages, balances the M1 / M2 cell levels, promotes cell proliferation, and effectively treats wound healing caused by diabetic bacterial infection.

[0043] It should be noted that, in this document, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. An antibacterial and immune-regulating hydrogel, characterized in that: The hydrogel includes oDex, EPL, TA and Fe 3+ , based on the Schiff base bond between oDex and EPL, the ionic bond and hydrogen bond between TA and EPL, and the 3+ The coordination effect can produce three hydrogels with photothermal-assisted antibacterial, antioxidant, anti-inflammatory and immune regulation functions; among them, oDex is obtained by oxidizing dextran with NaIO4.

2. The antibacterial and immune-regulating hydrogel according to claim 1, characterized in that: The oDex is prepared by oxidizing dextran with sodium periodate; the molecular weight of the dextran is 20,000 to 70,000 Da; and the mass ratio of NaIO4 to dextran is 0.64 to 1.28:

1.

3. The antibacterial and immune-regulating hydrogel according to claim 1, characterized in that: The preparation steps of oDex are as follows: 2 g of Dex with molecular weight of 20,000-70,000 Da was dissolved in 20 mL of deionized water; Dissolve 1.28-2.56 g NaIO4 in 12-24 mL deionized water; The NaIO4 solution was added dropwise to the Dex solution, and the mixture was stirred at room temperature for 1 to 4 h. Then, 1 mL of ethylene glycol was added dropwise to terminate the reaction. The mixture was dialyzed in deionized water and freeze-dried to prepare oDex.

4. The method for preparing an antibacterial and immunomodulatory hydrogel according to claim 1, characterized in that: The method comprises the following steps: S1. Dissolve oDex, EPL, TA, and FeCl3·6H2O in phosphate buffer respectively; S2, stir and mix oDex, EPL and TA, and add FeCl3·6H2O solution; S3. Add 1 M NaOH dropwise to the solution obtained in step S2 at 37° C. to prepare the hydrogel.

5. The method for preparing an antibacterial and immunomodulatory hydrogel according to claim 4, characterized in that: The oDex concentration is 1-7 w / v %; the EPL molecular weight is 2,000-5,000 Da; the EPL concentration is 1-4 w / v %; the TA concentration is 0-1 w / v %; Fe 3+ The concentration is 0~0.3 w / v %; and the amount of 1 M NaOH added is 0~20 μL.

6. The method for preparing an antibacterial and immunomodulatory hydrogel according to claim 5, characterized in that: The oDex concentration is 7 w / v%, the EPL molecular weight is 5,000 Da, and the EPL concentration is 4 w / v%. 3+ The concentration is 0.15w / v%.

7. Use of the antibacterial and immunomodulatory hydrogel according to any one of claims 1 to 3 in the preparation of medical antibacterial repair materials.

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