Ag@cfrs-loaded grifola frondosa polysaccharide-based hydrogel, preparation method and application thereof

Abstract

The application provides a gueanzhong polysaccharide-based hydrogel loaded with Ag@CFRs, a preparation method and application thereof, a stable three-dimensional network structure is formed through Schiff base reaction of oxidized gueanzhong polysaccharide and carboxymethyl chitosan, and phenolic aldehyde resin microspheres loaded with silver nanoparticles are introduced as functional nanofillers, the silver nanoparticles endow the hydrogel with broad-spectrum antibacterial ability, and effectively inhibit common pathogenic bacteria in a wound; the ortho-phenol groups in the phenolic aldehyde resin microspheres can efficiently remove active oxygen, and relieve oxidative stress; more importantly, the hydrogel can significantly down-regulate the expression of pro-inflammatory factors, up-regulate the expression of anti-inflammatory factors, promote the polarization of macrophages from M1 type to M2 type, fundamentally improve the immune microenvironment of a wound, and accelerate tissue repair and regeneration. The hydrogel also has good swelling property, water retention, biocompatibility and degradability, can provide a moist healing environment for a wound, and supports cell proliferation and migration, and exhibits important application value in the field of diabetic wound dressings.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, and in particular to a dermal polysaccharide-based hydrogel loaded with Ag@CFRs, its preparation method, and its application. Background Technology

[0002] Chronic wound healing in diabetes is a major challenge in clinical medicine. The healing process is often stalled at the inflammatory stage due to persistent oxidative stress and immune microenvironment dysregulation caused by hyperglycemia. In the diabetic wound environment, abnormally elevated levels of reactive oxygen species not only directly damage cells and tissues but also induce macrophages to persistently polarize into the pro-inflammatory M1 phenotype, inhibiting their transformation into the repair-functional M2 phenotype, making it difficult for the wound to enter the proliferation and remodeling phase. Furthermore, the impaired immune function of diabetic patients makes wounds susceptible to bacterial infection, further exacerbating the inflammatory response and creating a vicious cycle that severely hinders the healing process.

[0003] Currently, commonly used wound dressings in clinical practice, such as gauze and hydrocolloid dressings, mainly focus on physical barriers and exudate management, lacking the ability to actively regulate the wound microenvironment. In recent years, hydrogels have been regarded as ideal wound dressing carriers due to their high water content, good biocompatibility, and ability to carry functional components. However, most existing hydrogel dressings still have significant shortcomings in dealing with the complex pathological environment of diabetic wounds: for example, single antibacterial hydrogels cannot effectively alleviate oxidative stress; while ordinary antioxidant hydrogels lack the ability to precisely regulate macrophage polarization, making it difficult to fundamentally reverse the inflammatory microenvironment of the wound. In addition, some studies have attempted to introduce metal nanoparticles or natural extracts to enhance function, but still face problems such as poor material stability, high biotoxicity, and limited functionality, failing to meet the demand for multifunctional synergistic effects in diabetic wound repair.

[0004] Therefore, developing a multifunctional hydrogel dressing that combines good biocompatibility, high antibacterial and antioxidant capabilities, and the ability to actively regulate the immune microenvironment and promote macrophage polarization toward the repair phenotype has become a key technical problem that urgently needs to be solved in the field of diabetic chronic wound treatment. Summary of the Invention

[0005] The purpose of this invention is to provide a dermal polysaccharide-based hydrogel loaded with Ag@CFRs, its preparation method, and its application, so as to solve the problems existing in the prior art.

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

[0007] This invention provides a dermal polysaccharide-based hydrogel loaded with Ag@CFRs, comprising a hydrogel matrix and silver nanoparticles dispersed therein; the hydrogel matrix is ​​formed by crosslinking oxidized dermal polysaccharide and carboxymethyl chitosan through a Schiff base reaction; the silver nanoparticles are catechol-formaldehyde resin microspheres loaded with silver nanoparticles.

[0008] Preferably, the oxidized terrestris polysaccharide is prepared by oxidizing terrestris polysaccharide with sodium periodate, and the mass concentration of the carboxymethyl chitosan is 4%-10%.

[0009] Preferably, the mass concentration of the carboxymethyl chitosan is 6%.

[0010] Preferably, the volume ratio of the oxidized dermal polysaccharide to the carboxymethyl chitosan solution is 1:1; each 0.1g of oxidized dermal polysaccharide corresponds to 0.01-0.05g of the composite nanoparticles.

[0011] Preferably, the amount of silver nanoparticles added is 0.02g per 0.1g of oxidized dermal polysaccharide.

[0012] This invention also provides a method for preparing a *Dendrobium nobile* polysaccharide-based hydrogel loaded with Ag@CFRs, comprising the following steps:

[0013] S1. Preparation of oxidized *Georgia zedoaria* polysaccharide: Mix *Georgia zedoaria* polysaccharide aqueous solution with sodium periodate, carry out oxidation reaction under light-protected conditions, add ethylene glycol to terminate the reaction after the reaction is completed, and obtain oxidized *Georgia zedoaria* polysaccharide by dialysis and freeze-drying.

[0014] S2. Preparation of silver nanoparticles: Silver nitrate, hexamethylenetetramine and catechol were mixed in water and subjected to a hydrothermal reaction to obtain catechol-formaldehyde resin microspheres loaded with silver nanoparticles.

[0015] S3. Preparation of hydrogel: Oxidized dermal polysaccharide is dissolved in water, silver nanoparticles are added and dispersed evenly, and then mixed with carboxymethyl chitosan solution. The mixture is then crosslinked in situ through Schiff base reaction to obtain the dermal polysaccharide-based hydrogel loaded with Ag@CFRs.

[0016] Preferably, in step S1, the mass fraction of the dermal polysaccharide aqueous solution is 1%, and the oxidation reaction time is 6 hours; in step S2, the hydrothermal reaction temperature is 160°C, the reaction time is 6 hours, and the molar ratio of silver nitrate, hexamethylenetetramine, and catechol is 1:5:10.

[0017] Preferably, in step S3, the concentration of the oxidized dermal polysaccharide solution is 33.3 mg / mL, and the amount of composite nanoparticles added to the solution is 6.67 mg / mL.

[0018] The present invention also provides the application of Ag@CFRs-loaded dermal polysaccharide-based hydrogel in the preparation of medical dressings that promote wound healing.

[0019] Preferably, the wound is a chronic, difficult-to-heal wound caused by diabetes; the hydrogel accelerates wound healing by scavenging reactive oxygen species and promoting macrophage polarization from M1 to M2, and also has broad-spectrum antibacterial activity.

[0020] The present invention achieves the following beneficial technical effects compared to the prior art:

[0021] This invention provides a dermal polysaccharide-based hydrogel loaded with Ag@CFRs, its preparation method, and its applications, particularly suitable for the repair of chronic diabetic wounds. The hydrogel forms a stable three-dimensional network structure through a Schiff base reaction between dermal polysaccharide and carboxymethyl chitosan, and incorporates phenolic resin microspheres loaded with silver nanoparticles as functional nanofillers, achieving multifunctional synergy of antibacterial, antioxidant, and immunomodulatory effects. Specifically, the silver nanoparticles endow the hydrogel with broad-spectrum antibacterial capabilities, effectively inhibiting common pathogenic bacteria in wounds; the catechol groups in the phenolic resin microspheres can efficiently scavenge reactive oxygen species, alleviating oxidative stress; more importantly, this hydrogel can significantly downregulate the expression of pro-inflammatory factors and upregulate the expression of anti-inflammatory factors, promoting macrophage polarization from M1 to M2 types, thereby fundamentally improving the wound immune microenvironment and accelerating tissue repair and regeneration. Furthermore, this hydrogel also possesses good swelling properties, water retention, biocompatibility, and biodegradability, providing a moist healing environment for wounds and supporting cell proliferation and migration, demonstrating significant application value in the field of diabetic wound dressings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The invention demonstrates different morphologies in the hydrogel preparation process, including the OHNVPS precursor solution before gelation, the OHC hydrogel after gelation, and the ACOHC composite hydrogel.

[0024] Figure 2 Bar chart showing the equilibrium swelling ratio of OHC and ACOHC hydrogels at different CMCS concentrations.

[0025] Figure 3 The graph shows the change in water retention performance of different hydrogel samples over time.

[0026] Figure 4The graph shows the in vitro degradation rate of different hydrogel samples over time.

[0027] Figure 5 The results of CCK-8 assay were used to determine the cytotoxicity of different hydrogel extracts on L929 cells.

[0028] Figure 6 Photographs of plate colonies and statistical graphs of inhibition rate in the in vitro antibacterial experiment of hydrogel.

[0029] Figure 7 Flow cytometry results and statistical analysis of ROS removal in RAW264.7 cells using hydrogel.

[0030] Figure 8 The results of RT-qPCR detection of the regulation of macrophage polarization-related gene (CD86, TNF-α, CD206, IL-10) expression by hydrogel were obtained.

[0031] Figure 9 Gross photographs and quantitative analysis charts of the healing process of wounds on the backs of diabetic mice. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions and conditions described in the manual, or under conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market.

[0033] Example 1: Preparation of Ag@CFRs nanoparticles

[0034] 1 mmol of silver nitrate was dissolved in 200 mL of deionized water and magnetically stirred until completely dissolved. Then, a mixture containing 5 mmol of hexamethylenetetramine (HMT) and 10 mmol of catechol was slowly added to the solution, and stirring was continued for 30 minutes until homogeneous. The resulting mixture was transferred to a 250 mL hydrothermal reactor lined with polytetrafluoroethylene (PTFE), sealed, and heated in a 160°C oven for 6 hours. After the reactor cooled naturally to room temperature, the reaction product was centrifuged at 8000 rpm for 10 minutes to collect the precipitate. The precipitate was washed three times alternately with anhydrous ethanol and deionized water to thoroughly remove unreacted monomers and byproducts. Finally, the washed product was dried in a 50°C vacuum oven for 12 hours to obtain black powdery catechol-formaldehyde resin microspheres (Ag@CFRs) loaded with silver nanoparticles.

[0035] Example 2: Preparation of Oxidized Dendrocal Polysaccharide (OHNVPS)

[0036] like Figure 1 As shown, 1.0 g of purified dermal polysaccharide (HNVPS) was weighed and dissolved in 99 mL of distilled water to prepare a 1% (w / w) solution. Under light-protected conditions, 0.7 g of sodium periodate (NaIO4) was added to the solution, and the mixture was magnetically stirred continuously at room temperature for 6 hours to selectively oxidize the ortho-dihydroxyl groups on the polysaccharide chains to aldehyde groups. After the reaction was complete, 5 mL of ethylene glycol was added dropwise to the reaction solution, and stirring was continued for 2 hours to quench excess sodium periodate. The reaction solution was transferred to a dialysis bag with a molecular weight cutoff of 8-14 kDa and dialyzed under running tap water for 72 hours, followed by dialyzed with distilled water for 24 hours. Finally, the dialysate was freeze-dried to obtain a white flocculent solid of oxidized dermal polysaccharide (OHNVPS). Characterization was performed by Fourier transform infrared spectroscopy (FT-IR) at 1720 cm⁻¹. -1 A distinct aldehyde (C=O) characteristic absorption peak was observed nearby, confirming successful oxidation.

[0037] Example 3: Preparation of Ag@CFRs-loaded dermal polysaccharide-based hydrogel (ACOHC)

[0038] (1) Weigh 0.1g of OHNVPS prepared in Example 2, dissolve it in 3mL of distilled water, and stir gently until completely dissolved to obtain an OHNVPS solution with a concentration of 33.3mg / mL.

[0039] (2) Accurately add 0.02g of Ag@CFRs powder prepared in Example 1 to the above solution, place the mixture in an ultrasonic cleaner, and ultrasonically disperse it for 30 minutes at a power of 300W and a frequency of 40kHz until a uniform black suspension is formed.

[0040] (3) Weigh out carboxymethyl chitosan (CMCS) powder, dissolve it in distilled water, and prepare CMCS solutions with a mass fraction of 4%, 6%, 8%, and 10%.

[0041] (4) Take 1.5 mL of the suspension prepared in step (2) and quickly mix it with an equal volume (1.5 mL) of 4%, 6%, 8%, and 10% CMCS solutions, respectively, and vortex for 10 seconds. Then, let the mixture stand at room temperature. The aldehyde groups on the OHNVPS molecular chain react with the amino groups on the CMCS molecular chain to form a dynamic Schiff base reaction, and a hydrogel can be formed in situ within about 1-3 minutes. Label the resulting hydrogels as 4% ACOHC, 6% ACOHC, 8% ACOHC, and 10% ACOHC, respectively.

[0042] (5) Preparation of control group (OHC hydrogel): Except for not adding Ag@CFRs powder, the other steps are the same as those in (1), (3), and (4) above. That is, 0.1g OHNVPS is dissolved in 3mL of distilled water and then directly mixed with an equal volume of CMCS solutions of different concentrations. After standing, hydrogels of 4% OHC, 6% OHC, 8% OHC, and 10% OHC are obtained.

[0043] Example 4: Characterization of the theoretical properties of hydrogels

[0044] The swelling properties, water retention properties, and in vitro degradation properties of the series of hydrogels prepared in Example 3 were tested, and the results are as follows: Figures 2-4 As shown.

[0045] The swelling properties of the hydrogel were determined by a gravimetric method. Pre-weighed lyophilized hydrogels (W0) were immersed in phosphate-buffered saline (PBS, pH 7.4) at 37°C. Samples were removed at preset time points (10, 30, 60, 120, 240, and 360 min), excess surface moisture was blotted off, and the wet weight (W) was measured. t (This process continues) until swelling equilibrium is reached. The formula for calculating the equilibrium swelling rate is as follows:

[0046] ;

[0047] Hydrogels that have reached swelling equilibrium (W) eq The samples were placed in a 37°C constant temperature oven. The weights (W) of the samples were measured at 2, 4, 8, 12, 24, and 48 hours. t The formula for calculating the water retention rate is as follows:

[0048] ;

[0049] In vitro degradation performance determination: Accurately weigh the freeze-dried hydrogel sample and record its initial dry weight as W0. Immerse the sample in a container containing PBS buffer (pH 7.4, 0.01M) and incubate in a 37°C shaker. Remove the sample on days 3, 7, 14, 21, and 28, wash with deionized water to remove surface salts, freeze-dry to constant weight, and weigh the remaining dry weight, recording it as W0. d The degradation rate is calculated using the following formula (all experiments were performed in parallel three times, i.e., n=3):

[0050] ;

[0051] Results Analysis: With increasing CMCS concentration (4%-10%), the equilibrium swelling ratio of the hydrogel showed a concentration-dependent decreasing trend. The 6% concentration group maintained high liquid absorption capacity while avoiding the problem of excessively loose network in the low concentration group, achieving the optimal balance between swelling performance and network density. The introduction of Ag@CFRs (ACOHC series) increased network density by having nanoparticles act as physical cross-linking points. Although the swelling ratio was slightly lower than that of the pure OHC group, it significantly improved structural stability and water retention. Experiments confirmed that the 6% ACOHC group exhibited excellent water retention capacity (approximately 60% water retention rate after 5 hours) and moderate degradation kinetics. This overcame the defect of excessively rapid degradation leading to structural collapse in the 4% group and avoided the problem of limited swelling in the high concentration group, meeting the dual requirements of long-lasting wound dressings for maintaining a moist environment and scaffold stability.

[0052] Example 5: Cell compatibility evaluation

[0053] The cytotoxicity of hydrogel extracts against mouse fibroblasts (L929) was assessed using the CCK-8 assay. Extracts were prepared by soaking each hydrogel sample in sterile PBS at 37°C for 24 hours (extraction ratio: 0.1 g / mL). L929 cells were seeded in 96-well plates. After cell attachment, the medium was replaced with culture medium containing different concentrations of hydrogel extracts (negative and positive controls were included). After culturing for 24 and 48 hours, CCK-8 reagent was added for incubation, and absorbance at 450 nm was measured using a microplate reader. The relative cell viability (%) was calculated. Results are shown below. Figure 5 As shown.

[0054] Results Analysis: CCK-8 assay results showed that all hydrogel samples exhibited good biocompatibility with L929 fibroblasts. The pure OHC group showed near 100% cell viability, confirming the non-toxic nature of the matrix material. Although the ACOHC group contained silver, the 48-hour cell viability of all samples remained above 80%, meeting the biomaterial safety standard (ISO 10993-5). Notably, the cell activity of the 6% ACOHC group was significantly better than that of the 4% ACOHC group. This indicates that the moderately dense network formed at the 6% concentration effectively regulated the sustained release of Ag⁺, avoiding the acute stimulation to cells caused by the sudden release of silver ions due to a loose structure (such as the 4% group), confirming the excellent safety of this formulation.

[0055] Example 6: Evaluation of in vitro antibacterial properties

[0056] In this embodiment, the CCK-8 assay was used to evaluate the cytocompatibility of hydrogel and OHNVPS with L929 fibroblasts. First, material extracts were prepared according to ISO 10993-5 standard. Sterilized hydrogel (0.1 g) and solid OHNVPS (1.67 mg) were each immersed in 1 mL of complete culture medium and incubated at 37 °C for 24 h. The supernatant was collected and filtered through a 0.22 μm filter membrane to obtain a sterile extract. Subsequently, cells were cultured at 1 × 10⁻⁶ cells / mL. 4 Cells were seeded at a density of [number] cells / well in 96-well plates and incubated for 24 h to allow adhesion. The original culture medium was discarded, and the prepared sterile extract was added, followed by co-incubation for 24 h and 48 h, respectively. After incubation, 10 μL CCK-8 reagent was added to each well, and incubation continued for 2 h. The absorbance at 450 nm was measured using a microplate reader. The absorbance values ​​of the experimental group, control group (without extract), and blank group (cell-free) were recorded separately and denoted as [data missing]. , and And calculate the relative cell viability according to the formula.

[0057] ;

[0058] Results Analysis: The polysaccharide components alone (OHNVPS and OHC hydrogels) showed weak antibacterial activity. However, the ACOHC series hydrogels with added Ag@CFRs exhibited significant broad-spectrum antibacterial activity, with 6% ACOHC achieving inhibition rates of 75% against Escherichia coli and 70% against Staphylococcus aureus. This is mainly attributed to the bactericidal effect of the continuously released silver ions from Ag@CFRs, and the synergistic effect of the catechol groups on the surface of the phenolic resin microspheres disrupting bacterial cell membranes.

[0059] Example 7: Evaluation of antioxidant and immunomodulatory properties

[0060] 7.1 Intracellular ROS scavenging ability

[0061] The ability of hydrogels to scavenge intracellular reactive oxygen species (ROS) was assessed using the DCFH-DA fluorescent probe method. An inflammation model (M1 type) was established by stimulating RAW264.7 macrophages with lipopolysaccharide (LPS) and interferon-gamma (IFN-γ). After treating cells with 6% OHC and 6% ACOHC hydrogel extracts for 4 hours, respectively, DCFH-DA probes were added for incubation. Intracellular fluorescence intensity (reflecting ROS levels) was detected by flow cytometry. Untreated cells served as a blank control, and the LPS / IFN-γ stimulation group served as the model control. Results are as follows: Figure 7As shown, compared with the model group (relative fluorescence intensity set at 1.8), the fluorescence intensity of cells treated with 6% ACOHC significantly decreased to approximately 1.0, while the decrease in the 6% OHC group was smaller. This indicates that 6% ACOHC hydrogel can effectively remove excess ROS in cells under inflammatory conditions and alleviate oxidative stress.

[0062] 7.2 Regulation of Macrophage Polarization

[0063] The expression of macrophage polarization-related genes was detected by RT-qPCR. The treatment method was the same as in 7.1. After cell collection, total RNA was extracted and reverse transcribed into cDNA. Specific primers were used to amplify the mRNA of M1 markers (CD86, TNF-α) and M2 markers (CD206, IL-10), using GAPDH as an internal control, and the relative gene expression levels were calculated. Results are as follows: Figure 8 As shown in the figure, compared with the model group, 6% ACOHC treatment significantly downregulated the expression of pro-inflammatory genes CD86 and TNF-α (P<0.01), while significantly upregulating the expression of anti-inflammatory repair genes CD206 and IL-10 (P<0.01). The regulatory effect of the 6% OHC group was weaker. This demonstrates that 6% ACOHC hydrogel can effectively reverse the inflammatory microenvironment by scavenging ROS and its own biological activity, promoting macrophage polarization from pro-inflammatory M1 type to anti-inflammatory repair M2 type.

[0064] Example 8: Evaluation of in vivo diabetic wound healing

[0065] A streptozotocin (STZ)-induced type 1 diabetes mouse model was established. After the mice achieved stable hyperglycemia, a full-thickness skin defect of approximately 8 mm in diameter was created on their backs. Mice were randomly divided into four groups (n=6): a model control group (covered only with sterile gauze), a commercial dressing group (Tegaderm™), a 6% OHC hydrogel treatment group, and a 6% ACOHC hydrogel treatment group. The dressing was changed regularly post-surgery, and the wound condition was photographed on days 0, 3, 7, 10, and 13. The wound healing rate was calculated using ImageJ software. Healing rate = (initial wound area - current unhealed area) / initial wound area × 100%. Main results are as follows: Figure 9 As shown.

[0066] Results Analysis: To verify the repair efficacy of the hydrogel of this invention under pathological conditions, a STZ-induced full-thickness skin defect model was established in diabetic mice. Macroscopic observation showed that the STZ group exhibited slow wound healing accompanied by significant inflammation, while the wound treated with 6% ACOHC hydrogel showed significantly accelerated contraction, with smooth new tissue and an appearance close to normal skin. Quantitative analysis indicated that the wound healing rate of the 6% ACOHC group was superior to that of the 6% OHC group and the positive control group (Tegaderm™) at all time points. Specifically, on postoperative day 3, the healing rate of the 6% ACOHC group reached approximately 50%, significantly higher than that of the STZ group (<20%), demonstrating excellent early inflammation control capabilities; by day 13, the wound healing rate of this group approached 100%, with no statistically significant difference from the healthy control group (Control). The results confirm that 6% ACOHC hydrogel can effectively improve the microenvironment of diabetic wounds and significantly promote rapid and high-quality healing of full-thickness skin defects.

[0067] Overall Conclusion

[0068] The above embodiments describe in detail the specific implementation of the present invention and provide sufficient experimental data. The results show that the ACOHC hydrogel provided by the present invention, composed of oxidized leucine, carboxymethyl chitosan, and Ag@CFRs, is not only simple to prepare under mild conditions, but also possesses excellent swelling and water retention properties, good biocompatibility, and stability. More importantly, this hydrogel integrates three core functions: broad-spectrum antibacterial activity, efficient ROS scavenging, and precise regulation of macrophage polarization (from M1 to M2 type). In a diabetic chronic non-healing wound model, it exhibits significantly better healing-promoting effects than single-component hydrogels and equivalent to or even better than commercial dressings, providing a novel, efficient, and multifunctional dressing solution for addressing the challenges of diabetic wound repair.

[0069] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] It should be noted that the components mentioned in the above embodiments are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0071] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A hydrogel of *Dendrobium nobile* polysaccharide loaded with Ag@CFRs, characterized in that, It includes a hydrogel matrix and silver nanoparticles dispersed therein; the hydrogel matrix is ​​formed by cross-linking oxidized dermal polysaccharide and carboxymethyl chitosan through a Schiff base reaction; the silver nanoparticles are catechol-formaldehyde resin microspheres loaded with silver nanoparticles.

2. The *Delphinium argenteum* polysaccharide-based hydrogel loaded with Ag@CFRs according to claim 1, characterized in that, The oxidized dermal polysaccharide is prepared by oxidizing dermal polysaccharide with sodium periodate, and the mass concentration of the carboxymethyl chitosan is 4%-10%.

3. The *Delphinium arvense* polysaccharide-based hydrogel loaded with Ag@CFRs according to claim 2, characterized in that, The mass concentration of the carboxymethyl chitosan is 6%.

4. The *Delphinium argenteum* polysaccharide-based hydrogel loaded with Ag@CFRs according to claim 1, characterized in that, The volume ratio of the oxidized dermal polysaccharide to the carboxymethyl chitosan solution is 1:1; each 0.1g of oxidized dermal polysaccharide corresponds to 0.01-0.05g of the silver nanoparticles.

5. The *Delphinium argenteum* polysaccharide-based hydrogel loaded with Ag@CFRs according to claim 4, characterized in that, The amount of silver nanoparticles added is 0.02g per 0.1g of oxidized dermal polysaccharide.

6. A method for preparing a *Delphinium polysaccharide-based* hydrogel loaded with Ag@CFRs according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of oxidized *Georgia zedoaria* polysaccharide: Mix *Georgia zedoaria* polysaccharide aqueous solution with sodium periodate, carry out oxidation reaction under light-protected conditions, add ethylene glycol to terminate the reaction after the reaction is completed, and obtain oxidized *Georgia zedoaria* polysaccharide by dialysis and freeze-drying. S2. Preparation of silver nanoparticles: Silver nitrate, hexamethylenetetramine and catechol were mixed in water and subjected to a hydrothermal reaction to obtain catechol-formaldehyde resin microspheres loaded with silver nanoparticles. S3. Preparation of hydrogel: Oxidized dermal polysaccharide is dissolved in water, silver nanoparticles are added and dispersed evenly, and then mixed with carboxymethyl chitosan solution. The mixture is then crosslinked in situ through Schiff base reaction to obtain the dermal polysaccharide-based hydrogel loaded with Ag@CFRs.

7. The method for preparing the Ag@CFRs-loaded dermal polysaccharide-based hydrogel according to claim 6, characterized in that, In step S1, the mass fraction of the dermal polysaccharide aqueous solution is 1%, and the oxidation reaction time is 6 hours; in step S2, the hydrothermal reaction temperature is 160℃, the reaction time is 6 hours, and the molar ratio of silver nitrate, hexamethylenetetramine, and catechol is 1:5:

10.

8. The method for preparing the Ag@CFRs-loaded dermal polysaccharide-based hydrogel according to claim 6, characterized in that, In step S3, the concentration of the oxidized dermal polysaccharide solution is 33.3 mg / mL, and the amount of composite nanoparticles added to the solution is 6.67 mg / mL.

9. The use of the Ag@CFRs-loaded dermal polysaccharide-based hydrogel according to any one of claims 1-5 in the preparation of medical dressings that promote wound healing.

10. The application of the Ag@CFRs-loaded dermal polysaccharide-based hydrogel according to claim 9 in the preparation of medical dressings that promote wound healing, characterized in that, The wound is a chronic, difficult-to-heal wound caused by diabetes; the hydrogel accelerates wound healing by scavenging reactive oxygen species and promoting macrophage polarization from M1 to M2, and also has broad-spectrum antibacterial activity.

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