A hydrogel dressing with dual-response properties, its preparation method, and its application.

Abstract

This invention relates to the field of medical materials, and discloses a hydrogel dressing with dual-response properties, its preparation method, and its applications. The dressing is composed of a visualization indicator layer and a pH / temperature-responsive treatment layer, composited through a gradient cross-linking interface: the indicator layer is composed of sodium alginate, PVP, and betalain, enabling visual monitoring of wound pH through pigment color development; the treatment layer uses gelatin / carboxymethyl cellulose as a matrix, loaded with chlorogenic acid and notoginseng saponins, forming a porous scaffold with a pore size of 50-200 μm, possessing dual pH / temperature-responsive drug release capabilities. Ca²⁺ is used in the preparation process. + The alternating spraying strategy of genipin constructs a gradient interface, which, combined with low-temperature plasma treatment, forms an interpenetrating network structure. The interface bonding strength is enhanced through secondary wet curing. This dressing achieves a synergistic effect of precise drug release and infection early warning through microenvironment response. It is especially suitable for the treatment of diabetic wound infections and has multiple functions such as real-time monitoring, intelligent drug release, and promotion of tissue repair.

Description

Technical Field

[0001] This invention relates to the field of medical materials, specifically to a visualized intelligent bilayer hydrogel dressing with dual pH / temperature response characteristics, its preparation method, and its application. Background Technology

[0002] Infection management of diabetic wounds is a challenge in clinical nursing. Traditional dressings usually only have the function of passively absorbing exudate or physical isolation, and cannot monitor changes in the wound microenvironment in real time or dynamically regulate drug release. In recent years, intelligent responsive hydrogel dressings have become a research hotspot due to their sensitivity to physiological signals, but their application still faces the following challenges: (1) Most dressings are designed for a single stimulus, while wound infection is usually accompanied by synergistic changes in local pH increase and temperature abnormality, and a single response mode is difficult to accurately match complex pathological conditions. (2) Existing indicator dressings mostly rely on synthetic dyes or metal nanoparticles, which have problems such as poor biocompatibility and low color stability. (3) Bilayer dressings often cause interfacial peeling due to differences in mechanical properties between layers. Traditional chemical cross-linking methods are prone to causing interfacial embrittlement, affecting the overall flexibility and long-term stability of the dressing. Conventional porous hydrogels have significant drug burst release phenomena, and the biodegradability of temperature-sensitive materials is poor, making it difficult to achieve on-demand drug release triggered by the infection microenvironment.

[0003] To address the aforementioned issues, existing technologies have attempted improvements through composite cross-linking or biomimetic structural strategies, but these still suffer from insufficient interfacial integration and difficulties in simultaneously achieving both responsiveness and biological function. For example, patent application CN118059295A discloses a pH-responsive drug-loaded hydrogel and its preparation method. This patented technology is based on a pH-responsive hydrogel formed by cross-linking polyvinyl alcohol and sodium alginate. Although this hydrogel dressing can release drugs according to pH changes, its single-layer structure cannot simultaneously achieve monitoring and treatment functions. Patent application CN119431837A discloses a bilayer hydrogel for wound repair and infection monitoring and its preparation method. Although this patented technology's bilayer hydrogel system achieves real-time monitoring of wound infection by integrating the pH-responsive color-changing properties of mulberry anthocyanins, its interlayer binding mechanism and responsive function design still have significant limitations. Specifically, the bilayer structure of this system using metal ion coordination crosslinking has inherent defects: First, the interfacial bonding strength based on ionic bonds is generally insufficient, which can easily lead to interlayer delamination in dynamic physiological environments, seriously affecting the mechanical reliability of the material; Second, its functional response mechanism has a single defect, with the controlled release behavior of anthocyanins only showing a univariate correlation with pH value and lacking dual environmental responsiveness to temperature signals, making it difficult to meet the clinical needs of multi-parameter dynamic regulation in complex pathological environments such as diabetic wounds.

[0004] Therefore, developing a smart dressing that combines real-time visual monitoring and dual-response drug release functions with stable interlayer bonding is of great significance for improving the treatment effect of diabetic wounds and reducing the risk of secondary infection. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a hydrogel dressing with dual-response properties, which integrates visual monitoring and intelligent treatment functions through a gradient interpenetrating interface.

[0006] This invention provides a bilayer hydrogel dressing with dual-response properties, comprising the following structure: a visualization indicator layer composed of sodium alginate, polyvinylpyrrolidone, and betaine; a pH / temperature responsive treatment layer composed of gelatin, carboxymethyl cellulose, chlorogenic acid, notoginsenosides, and genipin, and having a porous scaffold structure; the bilayer hydrogel is connected by a gradient cross-linking interface, wherein the gradient cross-linking interface is connected by Ca... 2+ - An interpenetrating network structure is formed by alternating crosslinking strategies with genipin and low-temperature plasma treatment.

[0007] In any of the above technical solutions, the weight percentage concentrations of each component of the double-layer hydrogel dressing are as follows: sodium alginate: 1-5wt%, polyvinylpyrrolidone: 3-8wt%, betaine group: 0.1-0.5wt%, gelatin: 5-7wt%, carboxymethyl cellulose: 3-5wt%, chlorogenic acid: 0.1-0.6wt%, notoginsenosides: 0.2-0.5wt%, genipin: 0.2-0.5wt%.

[0008] The present invention also provides a method for preparing a double-layer hydrogel dressing, comprising the following steps: (1) dissolving sodium alginate and polyvinylpyrrolidone in deionized water, stirring at 50-70°C for 1-3 hours, adding betaine, and dispersing by ultrasonication in the dark to obtain an indicator layer prepolymer; (2) dissolving gelatin and carboxymethyl cellulose in deionized water at 50-70°C, stirring until completely dissolved, adding chlorogenic acid and Panax notoginseng saponins, stirring at a constant temperature, cooling, adding genipin solution, mixing thoroughly, pouring into a mold, and placing in a humidity chamber for curing to form a pH / temperature responsive treatment layer; (3) using micro-spraying technology to coat the indicator layer prepolymer onto the pH / temperature responsive treatment layer, alternately spraying 0.1-1M CaCl2 solution and genipin solution to form a gradient interface, and then obtaining a hydrogel by low-temperature plasma treatment and secondary wet curing.

[0009] In any of the above technical solutions, the spraying volume ratio of CaCl2 solution to genipin solution in step (2) is (2-5):1, and the spraying interval is 5-10 min.

[0010] In any of the above technical solutions, the duration of the low-temperature plasma treatment in step (3) is 30-90s.

[0011] In any of the above technical solutions, the thickness of the pH / temperature responsive treatment layer surface in step (3) is 180-220 μm.

[0012] In any of the above technical solutions, the low-temperature plasma treatment in step (3) uses argon gas, and the argon gas flow rate is 10-20 sccm, the radio frequency power is 45-50W, and the treatment distance is 3-6cm.

[0013] The present invention also provides an application of a hydrogel dressing, specifically the use of any of the above-mentioned double-layer hydrogel dressings in the preparation of materials for treating diabetic wound infections.

[0014] The technical effects that can be achieved by adopting the technical solution of the present invention are as follows:

[0015] 1. The visual indicator layer utilizes the pH-sensitive color-changing properties of betalains. The indicator layer can exhibit significant color changes (red-purple-brown) at pH 7.0-9.0 on the wound surface, providing medical staff with intuitive infection warning signals and enabling real-time visual monitoring of the wound condition. This avoids the secondary damage caused by the frequent removal and testing required by traditional dressings.

[0016] 2. The treatment layer utilizes the synergistic effect of chlorogenic acid and notoginseng saponins, combined with the dual-response drug release characteristics of pH / temperature. The release is triggered by the increase of pH in the wound infection microenvironment / local heating, achieving precise on-demand drug delivery, improving antibacterial efficiency and reducing drug resistance. The treatment layer uses a directional porous scaffold (pore size 50-200μm) constructed with a gelatin / carboxymethyl cellulose composite system, which can not only efficiently absorb wound exudate, but its extracellular matrix-like topology can also promote fibroblast migration and angiogenesis, accelerate granulation tissue formation, and shorten the healing cycle.

[0017] 3. The gradient cross-linking interface uses Ca 2+ - The alternating cross-linking strategy of genipin, combined with low-temperature plasma treatment to form an interpenetrating network structure, can improve the interfacial bonding strength and effectively prevent the risk of delamination of the double-layer structure in a dynamic wound environment.

[0018] 4. The dual-layer independent design avoids interference between the color-developing and therapeutic components, and the light-shielding ultrasonic dispersion process improves the light stability of betalains. Micro-spraying gradient cross-linking technology combined with low-temperature plasma treatment achieves precise interface construction while avoiding organic solvent residue, and the entire process uses an aqueous reaction system, meeting the environmental protection requirements for medical device production.

[0019] 5. Through triple innovation in materials, structure, and process, this dressing overcomes the pain points of traditional dressings, such as lack of monitoring function, uncontrollable drug release, and weak interfacial bonding. This dressing is particularly suitable for treating diabetic wound infections, effectively relieving wound inflammation, promoting wound healing, and reducing infection recurrence rates. In addition to infection treatment, this dressing can also be applied to other types of chronic wounds, showing broad application prospects.

[0020] 6. All raw materials used are biocompatible, non-irritating to wounds, and promote wound healing. The preparation method is simple, easy to industrialize, and can meet clinical needs. Attached Figure Description

[0021] Figure 1 The color change of the hydrogel prepared in Example 1 under different pH conditions;

[0022] Figure 2 Scanning electron microscope image of the hydrogel treatment layer prepared in Example 1;

[0023] Figure 3 The drug release kinetic curves of the hydrogel prepared in Example 1 under different environmental parameters are shown; where A represents the change of cumulative chlorogenic acid release over time at 25°C, and B represents the change of cumulative chlorogenic acid release over time at 37°C.

[0024] Figure 4 The cell compatibility test results are for the hydrogel prepared in Example 1.

[0025] Figure 5 Changes in wounds in diabetic mice under different treatment groups;

[0026] Figure 6 The results of H&E staining in an experiment on infected wounds in diabetic mice. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] To make the above-mentioned objectives, features and advantages of this aspect more apparent and understandable, specific embodiments of this aspect are described in detail below.

[0030] Example 1

[0031] (1) Dissolve 3g sodium alginate and 5g polyvinylpyrrolidone in 92mL deionized water, stir magnetically at 60℃ for 2 hours until completely dissolved, add 0.3g betaine, and ultrasonically disperse under light-protected conditions (100W, 20 minutes) to obtain the indicator layer prepolymer solution;

[0032] (2) Dissolve 6g of gelatin and 4g of carboxymethyl cellulose in deionized water at 60℃ and stir until completely dissolved. Add 0.5g of chlorogenic acid and 0.3g of Panax notoginseng saponin. Stir at 45℃ for 1 hour. After cooling to 25℃, add 0.3g of genipin solution and mix thoroughly. Pour into a mold and place in a humidity chamber to cure for 24 hours (RH60%) to form a treatment layer.

[0033] (3) The indicator layer prepolymer liquid was uniformly coated on the surface of the treatment layer (thickness 200μm) using micro-spraying technology. 0.5mol / L CaCl2 solution (atomization pressure 0.2MPa) and 0.3wt% genipin solution were sprayed alternately at a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes between each cycle. Then, low temperature isoproton treatment was performed (Ar gas flow rate 15sccm, 50W radio frequency power, treatment distance 5cm, time 60 seconds). Secondary wet curing (37℃, 1 hour, RH 90%) was performed to complete the interpenetrating network crosslinking and obtain a bilayer hydrogel.

[0034] Example 2

[0035] (1) Dissolve 3g sodium alginate and 5g polyvinylpyrrolidone in 92mL deionized water, stir magnetically at 60℃ for 2 hours until completely dissolved, add 0.2g betaine, and ultrasonically disperse under light-protected conditions (100W, 20 minutes) to obtain the indicator layer prepolymer solution;

[0036] (2) Dissolve 6g of gelatin and 4g of carboxymethyl cellulose in deionized water at 60℃ and stir until completely dissolved. Add 0.4g of chlorogenic acid and 0.3g of notoginsenoside, stir at 45℃ for 1 hour, cool to 25℃ and add 0.3g of genipin solution. Mix thoroughly, pour into a mold, place in a humidity chamber and cure for 24 hours (RH 60%) to form a treatment layer.

[0037] (3) The indicator layer prepolymer liquid was uniformly coated on the surface of the treatment layer (thickness 180μm) using micro-spraying technology. 0.5mol / L CaCl2 solution (atomization pressure 0.2MPa) and 0.3wt% genipin solution were sprayed alternately at a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes between each cycle. Then, low temperature isoproton treatment was performed (Ar gas flow rate 15sccm, 50W radio frequency power, treatment distance 5cm, time 60 seconds). Secondary wet curing (37℃, 1 hour, RH 90%) was performed to complete the interpenetrating network crosslinking and obtain a bilayer hydrogel.

[0038] Example 3

[0039] (1) Dissolve 3g sodium alginate and 5g polyvinylpyrrolidone in 92mL deionized water, stir magnetically at 60°C for 2 hours until completely dissolved, add 0.2g betaine, and ultrasonically disperse under light-protected conditions (100W, 20 minutes) to obtain the indicator layer prepolymer solution;

[0040] (2) Dissolve 6g of gelatin and 4g of carboxymethyl cellulose in deionized water at 60℃ and stir until completely dissolved. Add 0.3g of chlorogenic acid and 0.4g of Panax notoginseng saponin. Stir at 45℃ for 1 hour. After cooling to 25℃, add 0.3g of genipin solution and mix thoroughly. Pour into a mold and place in a humidity chamber to cure for 24 hours (RH 60%) to form a treatment layer.

[0041] (3) The indicator layer prepolymer liquid was uniformly coated on the surface of the treatment layer (thickness 220μm) using micro-spraying technology. 0.5mol / L CaCl2 solution (atomization pressure 0.2MPa) and 0.3wt% genipin solution were sprayed alternately at a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes between each cycle. Then, low temperature isoproton treatment was performed (Ar gas flow rate 15sccm, 50W radio frequency power, treatment distance 5cm, time 60 seconds). Secondary wet curing (37℃, 1 hour, RH 90%) was performed to complete the interpenetrating network crosslinking and obtain a bilayer hydrogel.

[0042] Example 4

[0043] (1) Dissolve 3g sodium alginate and 5g polyvinylpyrrolidone in 92mL deionized water, stir magnetically at 60°C for 2 hours until completely dissolved, add 0.4g betaine, and ultrasonically disperse under light-protected conditions (100W, 20 minutes) to obtain the indicator layer prepolymer solution;

[0044] (2) Dissolve 6g of gelatin and 4g of carboxymethyl cellulose in deionized water at 60℃ and stir until completely dissolved. Add 0.2g of chlorogenic acid and 0.3g of Panax notoginseng saponin. Stir at 45℃ for 1 hour. After cooling to 25℃, add 0.3g of genipin solution and mix thoroughly. Pour into a mold and place in a humidity chamber to cure for 24 hours (RH 60%) to form a treatment layer.

[0045] (3) The indicator layer prepolymer liquid was uniformly coated on the surface of the treatment layer (thickness 200μm) using micro-spraying technology. 0.5mol / L CaCl2 solution (atomization pressure 0.2MPa) and 0.3wt% genipin solution were sprayed alternately at a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes between each cycle. Then, low temperature isoproton treatment was performed (Ar gas flow rate 15sccm, 50W radio frequency power, treatment distance 5cm, time 60 seconds). Secondary wet curing (37℃, 1 hour, RH 90%) was performed to complete the interpenetrating network crosslinking and obtain a bilayer hydrogel.

[0046] Example 5

[0047] (1) Dissolve 3g sodium alginate and 5g polyvinylpyrrolidone in 92mL deionized water, stir magnetically at 60°C for 2 hours until completely dissolved, add 0.5g betaine, and ultrasonically disperse under light-protected conditions (100W, 20 minutes) to obtain the indicator layer prepolymer solution;

[0048] (2) Dissolve 6g of gelatin and 4g of carboxymethyl cellulose in deionized water at 60℃ and stir until completely dissolved. Add 0.1g of chlorogenic acid and 0.5g of Panax notoginseng saponin. Stir at 45℃ for 1 hour. After cooling to 25℃, add 0.3g of genipin solution and mix thoroughly. Pour into a mold and place in a humidity chamber to cure for 24 hours (RH 60%) to form a treatment layer.

[0049] (3) The indicator layer prepolymer liquid was uniformly coated on the surface of the treatment layer (thickness 200μm) using micro-spraying technology. 0.5mol / L CaCl2 solution (atomization pressure 0.2MPa) and 0.3wt% genipin solution were sprayed alternately at a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes between each cycle. Then, low temperature isoproton treatment was performed (Ar gas flow rate 15sccm, 50W radio frequency power, treatment distance 5cm, time 60 seconds). Secondary wet curing (37℃, 1 hour, RH 90%) was performed to complete the interpenetrating network crosslinking and obtain a bilayer hydrogel.

[0050] Comparative Example 1

[0051] The preparation process is basically the same as that in Example 1, except that chlorogenic acid was not added in step 2, and the hydrogel prepared is without chlorogenic acid.

[0052] Characterization

[0053] (1) To evaluate the wound monitoring performance of the hydrogel, the hydrogel samples prepared in Example 1 were placed in buffer solutions (pH 7.0-9.0) simulating different wound environments for colorimetric observation. Figure 1As shown, the material exhibits significant pH-dependent colorimetric properties: it displays a characteristic red color under conditions simulating the normal skin microenvironment (pH 7.0); when placed in a simulated infection environment (pH 8.0-9.0), the material shows a distinct purplish-red to brown color response. This gradient colorimetric property originates from the pH-sensitive chromophores introduced into the material, whose maximum absorption wavelength shifts systematically with changes in environmental pH. This allows the hydrogel to indicate the wound healing status in real time through visually perceptible color changes, providing an intuitive visual criterion for early warning of clinical infections.

[0054] (2) The treatment layer sample prepared in Example 1 was freeze-dried and then placed on a vacuum gold sputtering stage for gold sputtering. Its microstructure was then characterized using a scanning electron microscope (S-4800, Hitachi, Japan). Figure 2 As shown, the sample exhibits a typical hydrogel porous scaffold, presenting a three-dimensional interconnected porous network structure. The pores are interconnected through channels, forming a continuous three-dimensional framework, with the pore size uniformly distributed between 50-200 μm. This optimized hierarchical pore structure not only has a large specific surface area but also efficiently absorbs wound exudate through capillary action. At the same time, the interconnected three-dimensional channels provide ideal pathways for oxygen exchange and the transport of metabolic products, meeting the structural characteristics requirements of an ideal wound dressing.

[0055] (3) To systematically evaluate the drug release performance of the hydrogel, the drug release behavior of the chlorogenic acid-loaded hydrogel under different environmental parameters (pH 7.2 / 8.2, 25 / 37℃) was studied using ultraviolet-visible spectrophotometry. Specifically, the hydrogel sample prepared in Example 1 was placed in a dialysis apparatus containing PBS buffer, and drug release kinetics were studied under simulated physiological environment (pH 7.2, 37℃) and alkaline microenvironment (pH 8.2, 25℃), respectively. During the experiment, 3 mL of release medium was quantitatively transferred at predetermined time intervals, and an isothermal and equal volume of fresh PBS solution was immediately added to maintain a constant system volume. The absorbance value was measured at the characteristic absorption wavelength of 330 nm using a UV-Vis spectrometer, and the real-time cumulative release of chlorogenic acid was calculated using a pre-established standard curve (R²=0.9992).

[0056] like Figure 3The drug release kinetics curves show that environmental parameters significantly regulate the drug release behavior of the hydrogel: under the same temperature conditions (37℃), the cumulative release in an alkaline environment (pH 8.2) reached 78.2±2.3% after 48 hours, which is about 1.8 times higher than that in a neutral environment (pH 7.2); when the temperature rises from 25℃ to 37℃, the drug release rate constant under pH 8.2 conditions increases by 1.5 times. The microenvironment of diabetic infected wounds is usually weakly alkaline (pH 7.8-8.5) and accompanied by local temperature elevation (37-38℃). The enhanced release effect exhibited by this system under these conditions confirms that it can intelligently respond to changes in the lesion microenvironment to achieve on-demand drug delivery.

[0057] (4) The antibacterial performance evaluation experiment used the agar plate colony counting method, selecting Gram-negative Escherichia coli (E. coli) Escherichia coli ) and Gram-positive Staphylococcus aureus ( Staphylococcus aureus (This is used as the model strain.) The specific procedure is as follows: Accurately weigh 0.5g of the hydrogel sample prepared in Example 1 and 20mL of a solution with an initial concentration of 1×10⁻⁶. 7 After thorough mixing of the CFU / mL bacterial suspension, the mixture was transferred to a constant temperature shaking incubator and co-cultured at 37℃ and 180 rpm for 30 minutes. The cultured bacterial suspension was then serially diluted 10-fold. 100 μL of each appropriately diluted suspension was evenly spread onto LB agar plates and incubated at 37℃ for 12 hours before colony counting. The inhibition rate was calculated using the formula: Inhibition rate (%) = (Nc - Ns) / Nc × 100%, where Nc is the average colony count of the blank control group and Ns is the average colony count of the experimental group.

[0058] As shown in Table 1, all hydrogel samples exhibited significant antibacterial activity. Of particular note is that the sample examples showed significantly higher antibacterial efficiency against both test strains than the comparative group, and the antibacterial activity increased with increasing chlorogenic acid concentration.

[0059] Table 1. In vitro antibacterial rate of hydrogels

[0060] Escherichia coli inhibition rate (%) Staphylococcus aureus inhibition rate (%) Comparative Example 60.2 52.9 Example 1 97.3 96.9 Example 2 92.5 91.1 Example 3 89.6 80.8 Example 4 81.9 74.5 Example 5 76.4 68.6

[0061] (5) To evaluate the biocompatibility of the hydrogel prepared in Example 1, L929 mouse fibroblasts were used for in vitro cytotoxicity experiments. The specific procedure was as follows: 1×10⁻⁶ mcg of the hydrogel was used to prepare the hydrogel. 5Cell suspensions of 100 μL / well were seeded into 96-well plates and pre-cultured at 37°C in a 5% CO2 incubator for 24 hours to allow cell adhesion. Subsequently, the experimental group was replaced with fresh complete culture medium containing 100 μL of hydrogel extract (prepared according to ISO 10993-12 standard), while the control group received the same volume of complete culture medium. After culturing for 24, 48, and 72 hours, MTT assays were performed at each time point: 10 μL of MTT working solution (final concentration 0.5 mg / mL) was added to each well after discarding the culture medium, and the plates were incubated at 37°C in the dark for 4 hours to allow formazan crystals to form. The supernatant was then removed, and 100 μL of DMSO was added to dissolve the formazan crystals. The plates were gently shaken for 10 minutes using a micro-oscillator to ensure complete dissolution. Finally, the absorbance was measured at 570 nm using a microplate reader, and cell viability was calculated using the formula: Cell viability (%) = (Experimental group OD) / (OD) / (OD) / (OD / (OD) / (OD / (OD)). 570 Value / Control Group OD 570 (Value) × 100%.

[0062] like Figure 4 As shown, after co-culturing for different periods, the cell survival rate of the experimental group remained above 95%, indicating that the prepared hydrogel material did not exhibit significant cytotoxicity under in vitro conditions and met the safety standards for biomedical materials.

[0063] (6) The therapeutic effect of the bilayer hydrogel prepared in Example 1 on diabetic infected wounds. Eight male KM mice were selected and a type 1 diabetes model was established by intraperitoneal injection of streptozotocin (STZ) (dosage regimen: 50 mg / kg / day, for 5 consecutive days). The effectiveness of the model was verified by a continuous blood glucose monitoring system, with a fasting blood glucose level ≥11.1 mmol / L as the criterion for successful modeling. Seventy-two hours after modeling, the mice were anesthetized with isoflurane inhalation, and the surgical area was shaved with an electric shaver and disinfected with povidone-iodine. Two circular full-thickness skin defect models were symmetrically constructed on both sides of the spine using a sterile biopsy puncture device (6 mm in diameter). The experimental group was randomly divided into a control group (n=4) and a hydrogel group (n=4). The wounds of the control group were rinsed daily with PBS buffer (pH 7.4) and kept moist. The wounds of the hydrogel group were cleaned and uniformly covered with the hydrogel prepared in Example 1 (approximately 2 mm thick). Both groups of subjects received daily dressing changes and the wound healing process was systematically recorded. Wound images were captured on postoperative days 0, 3, 7 and 14.

[0064] Wound healing status as follows Figure 5 As shown, the healing speed of infected wounds treated with the bilayer hydrogel group was significantly faster than that treated with PBS buffer (pH 7.4), indicating that the bilayer hydrogel prepared in this invention has a good wound healing effect.

[0065] H&E staining histological analysis results (see) Figure 6 This further confirmed the above findings. On postoperative day 14, approximately 40% of the wound in the control group remained unclosed, with persistent inflammatory cell infiltration and loose, disordered granulation tissue. In contrast, the hydrogel group showed complete reepithelialization, with a continuous and intact epidermis, well-organized collagen fibers in the dermis, and complete disappearance of inflammatory cell infiltration. Its histomorphological characteristics were highly similar to those of normal skin tissue.

[0066] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A bilayer hydrogel dressing with dual-response properties, characterized in that, Includes the following structure: A visualization indicator layer, which is composed of sodium alginate, polyvinylpyrrolidone and betaine; pH / temperature responsive treatment layer: The pH / temperature responsive treatment layer is composed of gelatin, carboxymethyl cellulose, chlorogenic acid, notoginsenosides and genipin, and the pH / temperature responsive treatment layer has a porous scaffold structure; The bilayer hydrogel is connected by a gradient cross-linking interface, wherein the gradient cross-linking interface is connected by Ca 2+ - An interpenetrating network structure is formed by alternating crosslinking strategies with genipin and low-temperature plasma treatment.

2. The double-layer hydrogel dressing according to claim 1, characterized in that, The weight percentage concentrations of each component in the bilayer hydrogel dressing are shown below: The sodium alginate: 1-5 wt%, the polyvinylpyrrolidone: 3-8 wt%, the betaine group: 0.1-0.5 wt%, the gelatin: 5-7 wt%, the carboxymethyl cellulose: 3-5 wt%, the chlorogenic acid: 0.1-0.6 wt%, the notoginsenosides: 0.2-0.5 wt%, and the genipin: 0.2-0.5 wt%.

3. A method for preparing a bilayer hydrogel dressing with dual-response properties, characterized in that, The preparation method is used to prepare the bilayer hydrogel dressing as described in any one of claims 1-2, and includes the following steps: (1) Dissolve the sodium alginate and the polyvinylpyrrolidone in deionized water, stir at 50-70°C for 1-3 hours, add the betaine, and disperse by ultrasonication in the dark to obtain the indicator layer prepolymer solution; (2) Dissolve the gelatin and carboxymethyl cellulose in deionized water at 50-70°C, stir until completely dissolved, add the chlorogenic acid and the notoginseng saponin, stir at a constant temperature, cool and add the genipin solution, mix thoroughly, pour into a mold, and place in a humidity chamber for curing to form the pH / temperature responsive treatment layer. (3) The indicator layer prepolymer liquid is coated onto the pH / temperature responsive treatment layer using micro-spraying technology, and 0.1-1M CaCl2 solution and genipin solution are sprayed alternately to form a gradient interface. Then, the hydrogel is obtained by low-temperature plasma treatment and secondary wet curing.

4. The preparation method according to claim 3, characterized in that, In step (3), the spraying volume ratio of the CaCl2 solution to the genipin solution is (2-5):1, and the spraying interval is 5-10 min.

5. The preparation method according to claim 3, characterized in that, The duration of the low-temperature plasma treatment in step (3) is 30-90s.

6. The preparation method according to claim 3, characterized in that, The thickness of the pH / temperature responsive treatment layer surface described in step (3) is 180-220 μm.

7. The preparation method according to claim 3, characterized in that, The low-temperature plasma treatment in step (3) uses argon gas, and the flow rate of the argon gas is 10-20 sccm, the radio frequency power is 45-50W, and the treatment distance is 3-6cm.

8. The application of a bilayer hydrogel dressing with dual-response properties, characterized in that, The use of the bilayer hydrogel dressing as described in any one of claims 1-2 in the preparation of materials for treating diabetic wound infections.

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