A SAS-PAAS hydrogel loaded with dandelion extract, its preparation method and application

Abstract

This invention belongs to the field of hydrogel technology, specifically relating to sodium alginate sulfate-sodium polyacrylate (SAS-PAAS) hydrogel loaded with dandelion extract, its preparation method, and applications. This invention modifies sodium alginate using a NaHSO3 / NaNO2 system to prepare SAS, introducing sulfonic acid groups to improve water absorption and wound healing properties. The SAS is then combined with PAAS, utilizing the strong hydrophilicity and adhesiveness of PAAS to compensate for the insufficient mechanical properties of SAS alone. Through aluminum ion crosslinking and controlling the crosslinking density with sodium citrate, a three-dimensional porous network structure hydrogel with high adhesion, high mechanical strength, good swelling properties, and uniform texture is obtained. Dandelion extract is then introduced into the above hydrogel system to prepare a SAS-PAAS composite hydrogel wound dressing loaded with dandelion extract, which exhibits significant antibacterial activity and wound healing ability.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel technology, and specifically relates to a sodium alginate sulfate-sodium polyacrylate hydrogel (SAS-PAAS) loaded with dandelion extract, its preparation method and application. Background Technology

[0002] In the 1960s, researchers such as Winter proposed the theory of "moist wound healing," which states that compared to traditional dry healing, a moist environment significantly promotes the epithelialization and regeneration of wounds. This theory has driven innovation in modern wound dressings towards moisturizing, breathable, and biocompatible properties. Traditional dressings such as gauze or bandages are inexpensive, simple to manufacture, and have good moisture absorption, but their low water vapor permeability makes it difficult to maintain a moist wound environment. They may also adhere to tissues due to the absorption of exudate, causing secondary damage. Hydrogels, a hydrophilic three-dimensional network structure (containing 70%-90% water), have properties highly consistent with the theory of moist healing. They can absorb large amounts of water and biological fluids, and possess biodegradability, biocompatibility, and non-toxicity. They can maintain a moist wound environment, prevent bacteria from entering the wound, and can be applied in the field of wound dressings.

[0003] Natural polymer hydrogels are characterized by their wide availability of raw materials, non-toxicity, good biocompatibility, and biodegradability. Among them, sodium alginate (SA) has attracted much attention due to its excellent properties. However, monosodium alginate hydrogels have relatively low mechanical properties, stability, and limited functionality, which restricts their application in hydrogel wound dressings. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preparing SAS-PAAS hydrogels loaded with dandelion extract and their applications.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a SAS-PAAS hydrogel loaded with dandelion extract includes the following steps:

[0007] Preparation of S1, sodium alginate sulfate (SAS)

[0008] NaHSO3 and NaNO2 were dissolved in deionized water respectively. NaNO2 solution was added dropwise to the NaHSO3 solution under stirring. The reaction was carried out to prepare the esterifying agent sodium aminotrisulfonate N(SO3Na)3 solution. The pH was adjusted and sodium alginate was added. After the reaction was completed, ethanol was added, the mixture was filtered, the precipitate was collected, and it was washed repeatedly with anhydrous ethanol and distilled water. The precipitate was dried to constant weight to obtain the product SAS.

[0009] S2. Preparation of dandelion extract

[0010] Weigh an appropriate amount of dandelion, soak it in 75% ethanol solution, let it stand for 24 hours, extract it three times by ultrasonication, filter it, concentrate the filtrate to obtain dandelion extract.

[0011] S3. Preparation method of SAS-PAAS hydrogel loaded with dandelion extract

[0012] Dissolve SAS in deionized water, add sodium polyacrylate (PAAS), and stir until completely dissolved to obtain a polymer mixture solution. Add dandelion extract to the mixture. Dissolve AlCl3 in deionized water, add sodium citrate, adjust the pH, and add it dropwise to the polymer mixture solution while stirring. Allow to stand to obtain a hydrogel sample, sonicate to remove bubbles, and wash with water to remove unreacted monomers.

[0013] The purpose of step S1 is to chemically modify natural sodium alginate (SA) by introducing strongly hydrophilic sulfonic acid groups (-SO3H), thereby significantly altering its physicochemical properties. The reaction essentially involves sodium aminotrisulfonate (generated by the reaction of NaHSO3 and NaNO2) reacting with the hydroxyl groups (-OH) on the sodium alginate chain. The modified sodium alginate introduces sulfonic acid groups, which are strongly hydrophilic, even more so than the original hydroxyl and carboxyl groups, resulting in faster dissolution and stronger water absorption in the modified SAS. Furthermore, the sulfonic acid groups possess certain anticoagulant and antibacterial activities, synergistically interacting with the subsequently loaded dandelion extract, making it particularly suitable for wound dressings. The sulfonic acid groups can also interact with metal ions, providing more potential cross-linking sites for subsequent hydrogel formation.

[0014] In step S3, both SAS and PAAS are polyanions, carrying a large number of negatively charged -COO groups. - and -OSO3 - The added AlCl3 provides Al 3+ As a trivalent cation bridge, it can simultaneously bind with -COO on the SAS chain. - / -OSO3 - and the -COO on the PaaS chain - Coordination occurs, forming an "ionic cross-linked" network (SAS-COO). - —Al 3+ — - OOC-PAAS), this is the main reason for hydrogel formation. If AlCl3 solution is directly added to the SAS / PAAS mixture, a dense cross-linked shell will instantly form at the droplet contact interface, hindering the internal Al 3+ The entry of sodium citrate leads to uneven gelation, a hard core, and poor performance. After adding sodium citrate, the citrate ions affect the Al... 3+ It has extremely strong chelating ability and will preferentially bind with Al. 3+A stable, water-soluble aluminum citrate complex is formed. This complex has a high stability constant, but it competes for coordination with carboxyl and sulfonate groups on the polymer chain. With stirring and time, Al... 3+ It will be slowly released from the citric acid complex and then crosslinked with the polymer chain. This process achieves Al 3+ The slow and uniform release of the substance allows the cross-linking reaction to proceed synchronously and uniformly throughout the solution system, ultimately forming a hydrogel with a uniform structure, no internal defects, and excellent mechanical properties.

[0015] In step S2, dandelion extract (such as phenolic acid components) is uniformly dispersed in the polymer solutions of SAS and PAAS in solution. As the cross-linked network forms, these drug molecules are directly encapsulated within the three-dimensional micropores of the gel network. Phenolic hydroxyl groups and other functional groups in the extract may form hydrogen bonds with carboxyl, sulfonic acid, or hydroxyl groups on the polymer chains, further strengthening the binding and preventing premature drug leakage.

[0016] Furthermore, in step S1, the mass ratio of NaHSO3 to NaNO2 is 4:2.7; the mass ratio of NaHSO3 to sodium alginate is 4:1. The 4:1 ratio ensures a suitable grafting degree; a low grafting degree results in an insignificant modification effect (limited improvement in hydrophilicity and bioactivity). Excessive esterifying agent may lead to over-sulfonation, causing molecular chain degradation, or introduce excessive charge, making subsequent cross-linking processes difficult to control (overly dense cross-linking or precipitation).

[0017] Furthermore, in step S1, the reaction conditions for NaHSO3 and NaNO2 are 80°C for 1.5 h, and the reaction conditions for sodium alginate and esterifying agent are 60°C for 5 h.

[0018] Furthermore, in step S3, the mass ratio of SAS to PAAS is 1-3:1. This SAS to PAAS ratio determines the basic structure and properties of the hydrogel network. If the SAS ratio is too high, greater than 3:1, the gel tends to exhibit characteristics more similar to natural polysaccharides, resulting in better biocompatibility, but potentially weaker mechanical strength. If the PAAS ratio is too high, the gel has extremely strong water absorption and retention capabilities, leading to higher swelling, but may be too soft. A 1:1 ratio is preferred. A SAS:PAAS ratio of 1:1 provides the best swelling performance because a higher PAAS ratio provides more hydrophilic groups.

[0019] Furthermore, in step S3, the pH of the solution is 4-8.

[0020] Reason: pH is crucial for the success of the delayed cross-linking mechanism. If the pH is too high (>8), Al... 3+In an alkaline environment, Al(OH)3 precipitate will form, completely losing its cross-linking ability. At pH too low (<4), the carboxyl groups (-COOH) and sulfonic acid groups (-SO3H) on the polymer chain are protonated, becoming uncharged and unable to bind with Al. 3+ Effective coordination crosslinking results in gels failing to form or exhibiting extremely poor strength.

[0021] Furthermore, in step S3, the total mass ratio of SAS and PAAS to AlCl3 is 8-16:1. If there is too little AlCl3 as the crosslinking agent, there will be insufficient crosslinking points, resulting in a loose gel network with low strength and poor viscoelasticity. If there is too much AlCl3, the crosslinking points will be too dense, forming a brittle gel with low swelling degree, and the crosslinking may be too rapid to achieve homogenization, leading to uneven properties. The 8-16:1 ratio ensures the formation of a three-dimensional network with moderate crosslinking density, giving the hydrogel good mechanical strength, high swelling capacity, and elasticity.

[0022] Furthermore, in step S3, the mass fraction of AlCl3 in the AlCl3 aqueous solution is 4-6%.

[0023] Furthermore, in step S3, the mass ratio of sodium citrate to AlCl3 is 1:1. If there is too little sodium citrate, the chelation will be incomplete, resulting in a large amount of free Al³⁺. + It will cross-link rapidly, losing its delaying effect. Excessive sodium citrate may over-bind Al³⁺. + This can lead to difficulties in initiating the cross-linking reaction or excessively long gelation time.

[0024] Furthermore, in step S2, the mass of dandelion is 30 grams, and the volume of the final concentrate is 10 milliliters.

[0025] Beneficial technical effects of the present invention:

[0026] (1) Sulfonation modification and functional enhancement of SA

[0027] Sulfonation modification of SA using a NaHSO3 / NaNO2 system to prepare SAS introduces sulfonic acid groups. This modification not only preserves the biocompatibility of SA but also endows it with high negative charge properties, enabling it to regulate the inflammatory environment around macrophages in the wound microenvironment, thereby accelerating angiogenesis and tissue regeneration.

[0028] (2) Synergistic design and performance optimization of composite hydrogels

[0029] This innovative approach combines SAS (Self-Strength Assay) with PAAS (Pasteurized Assay), leveraging the strong hydrophilicity and adhesion of PAAS to compensate for the insufficient mechanical properties of SAS alone. Through Al... 3+Crosslinking and sodium citrate are used to regulate the crosslinking density. By combining orthogonal experiments to optimize process parameters (such as SAS:PAAS ratio, pH value, etc.), a three-dimensional porous network structure hydrogel with high adhesion, mechanical strength and swelling properties is obtained.

[0030] (3) Loading and synergistic treatment of natural active ingredients

[0031] For the first time, dandelion extract was loaded into SAS-PAAS hydrogel. The extract is rich in phenolic substances such as caffeic acid, luteolin, and quercetin, which can exert antibacterial, anti-inflammatory and antioxidant effects. It forms a synergistic therapeutic system with the moisturizing, liquid absorption and physical barrier building properties of the hydrogel, which significantly improves wound healing efficiency. Attached Figure Description

[0032] Figure 1 Flowchart for the preparation of SAS-PAAS composite hydrogel;

[0033] Figure 2 This is a schematic diagram of the microstructure of the SAS-PAAS composite hydrogel.

[0034] Figure 3 This is a diagram of the hydrogel's morphology before swelling.

[0035] Figure 4 This is a diagram showing the morphology of the hydrogel after swelling.

[0036] Figure 5 This is the swelling equilibrium curve;

[0037] Figure 6 Morphological diagram of the hydrogel prepared under optimal conditions;

[0038] Figure 7 SEM image (100 μm) of SAS-PAAS hydrogel.

[0039] Figure 8 SEM image (20 μm) of SAS-PAAS hydrogel;

[0040] Figure 9 Infrared spectra of SAS and SA;

[0041] Figure 10 The water retention curve of SAS-PAAS hydrogel;

[0042] Figure 11 The image shows the inhibitory effect on Staphylococcus aureus.

[0043] Figure 12 This is a diagram showing the wound healing process in mice. Detailed Implementation

[0044] The present application will be further described below with reference to the accompanying drawings.

[0045] I. Investigation of Reaction Conditions

[0046] 1.1、(1) Preparation of SAS

[0047] Weigh 8g of NaHSO3, dissolve it in 30mL of deionized water, and then place the solution in a 250mL three-necked flask. Weigh 5.4g of NaNO2 and dissolve it in 10mL of deionized water. Place the three-necked flask in a constant temperature water bath. Under stirring, add NaNO2 solution dropwise to the NaHSO3 solution and react at 80℃ for 1.5h to prepare the esterifying agent sodium aminotrisulfonate N(SO3Na)3.

[0048] The pH of the prepared reaction solution was adjusted to 9. 2g of sodium alginate was added to the reaction solution with stirring, and the mixture was reacted at 60℃ for 5 hours to obtain a brownish-yellow solution. Excess anhydrous ethanol was added to the reaction solution, and the mixture was filtered, the precipitate was collected, and repeatedly washed with anhydrous ethanol and distilled water. The precipitate was dried to constant weight in a 30℃ forced-air drying oven to obtain the product SAS.

[0049] The reaction equation for the preparation by SAS is as follows:

[0050] (2) Preparation method of SAS-PAAS hydrogel

[0051] A certain mass of SAS was dissolved in 50 mL of deionized water, and a certain mass of PAAS was added. The mixture was stirred at 50 °C until completely dissolved to obtain a mixed solution. A certain amount of AlCl3 was dissolved in deionized water. Then, a certain amount of sodium citrate was added at a mass ratio of 1:1 to prepare a solution of a certain concentration. The pH was adjusted, and this solution was added dropwise to the polymer solution while stirring. The mixture was allowed to stand at 30 °C to obtain a hydrogel sample. The sample was then placed in an ultrasonic bath to remove bubbles, and unreacted monomers were removed by washing with water. The flowchart for the preparation of the composite hydrogel is shown below. Figure 1 As shown in the diagram. A schematic diagram of the microstructure of the SAS-PAAS composite hydrogel is shown below. Figure 2 As shown.

[0052] 1.2 Orthogonal Experimental Design

[0053] The overall score was based on adhesion and swelling properties, with adhesion accounting for 50 points and swelling properties accounting for 50 points. L9(3) was used as the evaluation index. 4 The orthogonal experimental design tables (Tables 1 and 2) were used to investigate the selected factors, specifically the effects of the SAS:PAAS mass ratio, AlCl3 crosslinking agent concentration, crosslinking ratio, and pH value on the gel adhesion and swelling properties in step S2. Hydrogels were prepared according to the orthogonal experimental design tables and scored according to the scoring criteria (Table 3). The overall score = adhesion performance score + swelling performance score.

[0054] Table 1. Factor Level Table

[0055]

[0056] Table 2. Orthogonal experimental design

[0057]

[0058] Table 3. Evaluation Criteria

[0059]

[0060] 1.3 Results Analysis

[0061] (1) Adhesion performance test: The adhesion performance of hydrogel is evaluated by comprehensive sensory evaluation. Adhesion performance score = tack score + spreadability score + gel residue score + firmness score + appearance score.

[0062] The results show that hydrogels, possessing a certain degree of adhesion, can adhere well to wound sites, thereby resisting the invasion of microorganisms from the external environment. Furthermore, when a wound bleeds, it can seal the bleeding site and reduce the amount of bleeding. Table 4 shows that the order of adhesion performance is 4>3=7=8>2>9>5>6>1.

[0063] Table 4. Adhesion performance test results

[0064]

[0065] (2) Swelling performance test:

[0066] The prepared hydrogels under different conditions were dried in a forced-air drying oven at 50°C for 24 hours. Each sample was weighed, and the dry sample mass was recorded as M1. The samples were then soaked in physiological saline, and excess water was filtered off at different times. The surface moisture was blotted dry with filter paper, and the samples were weighed again until the gel reached swelling equilibrium. The mass after swelling was recorded as M2. The degree of swelling was calculated using the following formula; a higher degree of swelling indicates better swelling performance.

[0067] The results are as follows: a comparison of the morphology before and after swelling. Figure 3 and Figure 4 As shown in Table 5, the excellent swelling properties of the SAS-PAAS hydrogel are clearly demonstrated. Figure 5 It can be seen that the swelling performance is in the order of 1>2>3>5>6>4>9>7>8. The swelling performance is best when the SAS:PAAS ratio is 1:1 because a higher proportion of PAAS provides more hydrophilic groups. The swelling performance is good when the crosslinking agent concentration is 4% because the lower crosslinking density results in a larger pore structure leading to stronger water absorption. The swelling performance is good at pH 4 because some of the PAAS's -COO groups... -It is protonated to -COOH, reducing its interaction with Al. 3+ The cross-linking points decrease, the cross-linking density decreases, resulting in a looser network, increased pore size, and enhanced water absorption capacity.

[0068] Table 5. Swelling Test Data

[0069]

[0070] (3) Results of orthogonal experiments

[0071] The results of the orthogonal experiment are shown in Table 6. The order of influence of each factor on the experimental results is SAS:PAAS > pH value = crosslinking ratio > crosslinking agent concentration. The optimal combination is SAS:PAAS 1:1, crosslinking agent concentration 4%, crosslinking ratio 12:1, and pH value 8.

[0072] Table 6. Results of the orthogonal experiment

[0073]

[0074] (4) Based on the orthogonal experiment results, three hydrogels (numbered 1, 2, and 3) were prepared under the optimal preparation conditions, and their comprehensive scores were examined. If the comprehensive score is the highest score in the orthogonal experiment results, then the optimized hydrogel preparation conditions are feasible. The scoring results of the three hydrogels prepared under the optimal conditions are shown in Table 7. The average comprehensive score of the three samples was 91.33, which is higher than the comprehensive scores of the nine groups in the orthogonal table, indicating that the optimized hydrogel preparation conditions are feasible. Moreover, the hydrogels prepared under these conditions have excellent adhesion properties, mechanical properties, and swelling properties (see Table 7). Figure 6 ).

[0075] Table 7. Verification Test Results

[0076]

[0077] Example 1 (Verification of optimal process conditions)

[0078] (1) Preparation of SAS

[0079] Weigh 8g of NaHSO3, dissolve it in 30mL of deionized water, and then place the solution in a 250mL three-necked flask. Weigh 5.4g of NaNO2 and dissolve it in 10mL of deionized water. Place the three-necked flask in a constant temperature water bath. Under stirring, add NaNO2 solution dropwise to the NaHSO3 solution and react at 80℃ for 1.5h to prepare the esterifying agent sodium aminotrisulfonate N(SO3Na)3.

[0080] The pH of the prepared reaction solution was adjusted to 9. 2g of sodium alginate was added to the reaction solution with stirring, and the mixture was reacted at 60℃ for 5 hours to obtain a brownish-yellow solution. Excess anhydrous ethanol was added to the reaction solution, and the mixture was filtered to collect the precipitate, which was then repeatedly washed with anhydrous ethanol and distilled water. The precipitate was dried to constant weight in a 30℃ forced-air drying oven to obtain the product SAS.

[0081] (2) Preparation of dandelion extract

[0082] Weigh 30g of dandelion, soak it in 75% ethanol solution, let it stand for 24 hours, and then extract it by ultrasonication at 50℃ for 1 hour. Repeat the extraction 3 times, combine the filtrates and concentrate to obtain dandelion extract (each milliliter contains 3g of original dandelion).

[0083] (3) Preparation of SAS-PAAS hydrogel loaded with dandelion extract

[0084] Under optimal preparation conditions, a certain mass of SAS was weighed and dissolved in 50 mL of deionized water. A certain mass of PAAS was added, and the mixture was stirred at 50°C until completely dissolved to obtain a mixed solution. 1.5 mL of dandelion extract was added to the mixed solution. A certain amount of AlCl3 was dissolved in deionized water, and sodium citrate was added at a mass ratio of 1:1 to prepare a solution of a specific concentration, and the pH was adjusted. The SAS:PAAS ratio was 1:1, the crosslinking agent concentration was 4%, the crosslinking ratio was 12:1, and the pH value was 8.

[0085] The solution was added dropwise to the polymer solution with stirring, and the mixture was allowed to stand at 30°C to obtain a hydrogel sample. Unreacted monomers were removed by washing with water.

[0086] The hydrogel prepared in Example 1 was characterized.

[0087] (1) Morphological characterization of hydrogels

[0088] The microstructure of the SAS-PAAS hydrogel prepared in Example 1 with the optimal formulation was investigated using nanoscale scanning electron microscopy. The microstructure was examined at different magnifications (…). Figure 7 and Figure 8 Observation revealed that at 50x magnification, the hydrogel exhibited a porous network structure with a rough surface and irregular sheet-like or fibrous interweaving characteristics. Large pores were visible in some areas, indicating that the hydrogel formed a three-dimensional network structure from cross-linked polymer chains. Further magnification to 200x revealed an even clearer network structure with granular surface features, indicating uneven dispersion of sodium polyacrylate. Therefore, the composite gel formed a loose and uneven network structure with open pores.

[0089] (2) Infrared spectroscopy analysis

[0090] Figure 9 The image shows the infrared spectra of sodium alginate sulfate (SAS) and sodium alginate (SA). The image shows the infrared spectra of 3000-3500 cm⁻¹. -1 The absorption peak intensity of SAS in this region is weaker than that of SA due to the stretching vibration of -OH. This is because after sulfation modification, some hydroxyl groups are replaced by sulfate ester groups, weakening the hydrogen bonding between hydroxyl groups; 1600-1750 cm⁻¹ -1 The absorption peak at 1400-1440 cm⁻¹ is caused by the C=O in -COOH. -1 and 900-950cm -1 The absorption peak of OH in -COOH is 1210-1320 cm⁻¹. -1 The absorption peak of CO in -COOH is 1050-1200 cm⁻¹. -1 It is a COC stretching vibration, 1000-1100cm -1 The absorption peak in this region is weakened in SAS compared to SA due to CO stretching and skeletal vibrations. This is because side reactions occur, leading to the reaction of some carboxyl groups. The SA and SAS spectra show that two new characteristic absorption peaks appear in the SAS spectrum compared to SA. One is at 1241 cm⁻¹. -1 At this point, the absorption peak indicates the asymmetric stretching vibration of the S=O bond. Another absorption peak is at 858 cm⁻¹. -1 The absorption peak at this location indicates the symmetric stretching vibration of the COS bond. This demonstrates that sodium alginate has successfully introduced sulfate groups.

[0091] (3) Moisturizing performance analysis

[0092] Dehydration of the wound can lead to crusting and hinder healing. Good water retention keeps the wound moist, accelerates healing, and reduces scarring. Weigh the hydrogel by mass W. e The sample was placed at room temperature, and its mass W was measured at 0.5h, 1.0h, 2.0h, 3.0h, 4.0h, 5.0h, and 6.0h respectively. t Calculate the water retention rate using the formula below.

[0093] The water retention curve of SAS-PAAS hydrogel is shown below. Figure 10 The hydrogel retained approximately 81% of its water content after 6 hours. This indicates that the hydrogel, with its unique three-dimensional network structure and hydrophilic groups, can efficiently adsorb and fix water, providing a continuous and stable moist environment for the wound, thereby accelerating tissue repair and promoting wound healing.

[0094] (4) Antibacterial performance analysis

[0095] Staphylococcus aureus is a common opportunistic pathogen on the surface of human skin and mucous membranes. When a wound is broken, the skin barrier is damaged, and bacteria can directly invade from the edge of the wound, thereby delaying wound healing.

[0096] The results of the Staphylococcus aureus inhibition experiment are shown in Figure 11. Region 1 is the blank control, which has no inhibitory effect on Staphylococcus aureus and no inhibition zone. Region 2 is the positive control, which has a significant inhibitory effect on Staphylococcus aureus and forms an inhibition zone of 20 mm. Region 3 is the SAS-PAAS hydrogel loaded with dandelion extract, which has a weak inhibitory effect on Staphylococcus aureus and forms an inhibition zone of 10 mm. Region 4 is the SAS-PAAS hydrogel, which has a weak inhibitory effect on Staphylococcus aureus and does not produce a particularly obvious inhibition zone.

[0097] (5) Wound healing experiment

[0098] A full-thickness skin defect model was constructed in mice to investigate the effect of SAS-PAAS hydrogel loaded with dandelion extract on wound healing. Twenty SPF-grade male mice were randomly divided into four groups of five mice each: a control group, a commercial dressing group, a SAS-PAAS hydrogel group, and a SAS-PAAS hydrogel group loaded with dandelion extract. After anesthetizing the mice with ether, the hair on the backs of the mice was removed with depilatory cream, and the area was wiped clean with damp gauze or cotton balls to prevent skin burns. After hair removal, the area was disinfected with povidone-iodine, and then a circular wound with a diameter of 8 mm was created on the back of the mice using a perforation method. 1 g of the hydrogel and the commercial dressing were applied to the wound surface, respectively. The dressings were changed on days 1, 3, 5, 7, and 9 post-surgery, and the wound healing was observed.

[0099] Wound healing in mice as follows Figure 12 As shown, the wound area in the control group did not change much throughout the process, and the wound was dry, with severe scab formation and a darkening color. The wound healing rate in the commercial dressing group, the SAS-PAAS hydrogel group, and the SAS-PAAS hydrogel group loaded with dandelion extract was faster than that in the control group, and the wounds remained red and had less scab formation during the healing process. Compared with the commercial dressing group, the SAS-PAAS hydrogel group and the dandelion-loaded hydrogel group showed better wound repair and a smoother surface. Compared with the SAS-PAAS group, the wound area in the dandelion-loaded hydrogel group was significantly reduced on day 3, and by day 9, the wound had basically recovered to normal, with a more moist surface and better recovery.

[0100] The above results indicate that the SAS-PAAS hydrogel loaded with dandelion extract possesses excellent wound healing capabilities. This is likely due to the hydrogel's good water retention, which keeps the wound moist and prevents crusting; its swelling properties, which absorb wound exudate; and the physical barrier it forms, which blocks the invasion of bacteria and other microorganisms. The SAS hydrogel, due to the introduction of sulfonic acid groups, carries a high negative charge, which can alter the distribution of some heparin-binding proteins in the wound microenvironment, thereby regulating the inflammatory environment around macrophages. Simultaneously, the introduction of sulfonic acid groups in SAS stimulates macrophage polarization from M1 to M2 types. M2 macrophage-associated Arg-1 can produce ornithine to promote cell proliferation, and VEGF secretion can promote angiogenesis, thus enhancing the potential for tissue regeneration and recovery. Furthermore, dandelion extract contains a large amount of phenolic substances such as caffeic acid, luteolin, and quercetin, which have strong antibacterial, anti-inflammatory, and antioxidant activities, further enhancing wound healing capabilities. This type of hydrogel has potential applications in wound dressings.

[0101] This invention uses SAS and PAAS as gel matrices, and synthesizes a SAS-PAAS hydrogel with a three-dimensional network structure by crosslinking the sulfate and carboxyl groups of SAS with the carboxyl groups of PAAS using aluminum ions. Aluminum trichloride is selected as the crosslinking agent, and sodium citrate is added to slow down the crosslinking rate and prevent precipitation of the crosslinking agent. Orthogonal experiments determined the optimal preparation conditions to be SAS:PAAS 1:1, crosslinking agent concentration 4%, crosslinking ratio 12:1, and pH 8. The hydrogel with the optimal combination was prepared, and a SAS-PAAS composite hydrogel wound dressing was prepared by loading dandelion extract. The structure and properties of the hydrogel wound dressing with the optimal combination were characterized by SEM and other methods. The study shows that the SAS-PAAS hydrogel wound dressing has good adhesion, swelling properties, mechanical properties, moisturizing properties, and wound healing properties. Compared with the SAS-PAAS hydrogel, the addition of dandelion extract gives the hydrogel a certain antibacterial activity and shows better performance in promoting wound healing. The hydrogel prepared in this experiment is feasible for use as a wound dressing.

Claims

1. A method for preparing a SAS-PAAS hydrogel loaded with dandelion extract, characterized in that: Includes the following steps: Preparation of S1 and SAS NaHSO3 and NaNO2 were dissolved in deionized water respectively. NaNO2 solution was added dropwise to the NaHSO3 solution under stirring. The reaction was carried out to prepare the esterifying agent sodium aminotrisulfonate N(SO3Na)3 solution. The pH was adjusted and SA was added. After the reaction was completed, ethanol was added, the mixture was filtered, the precipitate was collected, and it was washed repeatedly with anhydrous ethanol and distilled water. The precipitate was dried to constant weight to obtain the product SAS. S2. Preparation of dandelion extract Weigh an appropriate amount of dandelion, soak it in 75% ethanol solution, let it stand for 24 hours, extract it three times by ultrasonication, filter it, concentrate the filtrate to obtain dandelion extract. S3. Preparation method of SAS-PAAS hydrogel loaded with dandelion extract Dissolve SAS in deionized water, add sodium polyacrylate (PAAS), and stir until completely dissolved to obtain a polymer mixture solution. Add dandelion extract to the mixture. Dissolve AlCl3 in deionized water, add sodium citrate, adjust the pH, and add it dropwise to the polymer mixture solution while stirring. Allow the mixture to stand to obtain a hydrogel sample. Defoam it by sonication and wash with water to remove unreacted monomers. In step S1, the mass ratio of NaHSO3 to NaNO2 is 4:2.7; the mass ratio of NaHSO3 to sodium alginate is 4:1; the reaction conditions for NaHSO3 and NaNO2 are 1.5 h at 80 °C, and the reaction conditions for sodium alginate and esterifying agent are 5 h at 60 °C. In step S3, the mass ratio of SAS to PAAS is 1-3:1; the mass ratio of the total mass of SAS and PAAS to AlCl3 is 8-16:1; the mass ratio of sodium citrate to AlCl3 is 1:1; and the pH of the solution is 4-8.

2. The method for preparing SAS-PAAS hydrogel loaded with dandelion extract according to claim 1, characterized in that: In step S3, the mass fraction of AlCl3 in the AlCl3 aqueous solution is 4-6%.

3. The method for preparing SAS-PAAS hydrogel loaded with dandelion extract according to claim 1, characterized in that: In step S2, the mass of dandelion is 30 grams, and the volume of the final concentrate is 10 milliliters.

4. A SAS-PAAS hydrogel loaded with dandelion extract prepared by the preparation method according to any one of claims 1-3.

5. The application of a SAS-PAAS hydrogel loaded with dandelion extract prepared by any one of claims 1-3 in the preparation of an antibacterial gel, wherein the application is for non-disease treatment and disease diagnosis purposes.

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