Hydrogel dressing with double response characteristics as well as preparation method and application of hydrogel dressing

Abstract

The invention relates to the field of medical materials, and discloses a hydrogel dressing with dual response characteristics, and a preparation method and application thereof. The dressing is formed by compounding a visual indication layer and a pH / temperature response treatment layer through a gradient cross-linking interface, wherein the indication layer is composed of sodium alginate, PVP and betacyanin, and visual monitoring of the pH of a wound surface is achieved through pigment developing; the treatment layer takes gelatin / carboxymethyl cellulose as a matrix and is loaded with chlorogenic acid and notoginsenoside to form a porous scaffold with the pore diameter of 50-200 microns, and the porous scaffold has a pH / temperature dual-response drug release function. In the preparation process, a gradient interface is constructed by adopting a Ca < + >-genipin alternate spraying strategy, an interpenetrating network structure is formed in combination with low-temperature plasma treatment, the interface bonding strength is enhanced through secondary wet curing, and the dressing realizes the synergistic effect of accurate drug release and infection early warning through microenvironment response, so that the dressing has a good application prospect. The system is especially suitable for diabetes wound infection treatment, and has multiple functions of real-time monitoring, intelligent drug release and tissue repair promotion.

Description

Technical Field

[0001] The present invention relates to the field of medical materials, and in particular to a visualized intelligent double-layer hydrogel dressing with pH / temperature dual response characteristics, and a preparation method and application thereof. Background Art

[0002] Infection management of diabetic wounds is a difficult problem in clinical care. Traditional dressings usually only have the functions 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, smart 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 only a single stimulus, while wound infection is usually accompanied by synergistic changes in local pH increase and abnormal temperature. It is difficult for a single response mode to accurately match complex pathological conditions. (2) Existing indicator dressings mostly rely on synthetic dyes or metal nanoparticles, which have problems of poor biocompatibility and low color stability. (3) Double-layer dressings often cause interfacial peeling due to differences in mechanical properties between layers. Traditional chemical cross-linking methods are prone to cause interfacial embrittlement, affecting the overall flexibility and long-term stability of the dressing. Conventional porous hydrogels have a significant drug burst release phenomenon, and thermosensitive materials have poor biodegradability, making it difficult to achieve on-demand drug release triggered by the infected microenvironment.

[0003] In view of the above problems, the prior art attempts to improve through composite cross-linking or structural biomimetic strategies, but there are still defects such as insufficient interface integration and difficulty in balancing response sensitivity and biological functions. For example, the patent application with publication number CN118059295A discloses a pH-responsive drug-loaded hydrogel and its preparation method. The patented technical solution is a pH-responsive hydrogel formed by cross-linking polyvinyl alcohol and sodium alginate. Although the hydrogel dressing can release drugs according to pH changes, its single-layer structure cannot simultaneously realize monitoring and treatment functions; the patent application with publication number CN119431837A discloses a double-layer hydrogel for wound repair and infection monitoring and its preparation method. Although the double-layer hydrogel system of the patented technical solution realizes real-time monitoring of wound infection by integrating the pH-responsive color-changing characteristics of mulberry anthocyanins, its interlayer binding mechanism and response function design still have significant limitations. Specifically, the system uses a double-layer structure with metal ion coordination cross-linking, which has inherent defects: first, the interface bonding strength based on ionic bonds is generally insufficient, which can easily cause interlayer delamination in a dynamic physiological environment, seriously affecting the mechanical reliability of the material; second, its functional response mechanism has a single defect, and the controlled release behavior of anthocyanins is only univariately correlated with the pH value, lacking dual environmental responsiveness to temperature signals, making it difficult to meet the clinical needs of dynamic regulation of multiple parameters in complex pathological environments such as diabetic wounds.

[0004] Therefore, developing an intelligent dressing that combines real-time visual monitoring with dual-response drug release functions and 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] In view of the above problems, the present invention proposes a hydrogel dressing with dual response characteristics, which integrates visual monitoring and intelligent treatment functions through a gradient interpenetrating interface.

[0006] The invention provides a hydrogel dressing with dual response characteristics, comprising the following structures: a visual indicator layer, which is composed of sodium alginate, polyvinyl pyrrolidone and betalain; a pH / temperature responsive therapeutic layer, which is composed of gelatin, carboxymethyl cellulose, chlorogenic acid, notoginseng saponin and genipin, and has a porous scaffold structure; the double-layer hydrogel is connected by a gradient cross-linking interface, wherein the gradient interface is connected by Ca 2+ -Genepin alternating cross-linking strategy and low-temperature plasma treatment formed an interpenetrating network structure.

[0007] In any of the above technical solutions, the weight percentage concentrations of the components of the double-layer hydrogel dressing are as follows: sodium alginate: 1-5wt%, polyvinyl pyrrolidone: 3-8wt%, betalain group: 0.1-0.5wt%, gelatin: 5-7wt%, carboxymethyl cellulose: 3-5wt%, chlorogenic acid 0.1-0.6wt%, notoginseng saponin: 0.2-0.5wt%, genipin: 0.2-0.5wt% The present invention also provides a method for preparing a hydrogel dressing, comprising the following steps: (1) dissolving sodium alginate and polyvinyl pyrrolidone in deionized water, stirring at 50-70°C for 1-3h, adding betaine, and performing ultrasonic dispersion in the dark to obtain an indicator layer prepolymer solution; (2) dissolving gelatin and carboxymethyl cellulose in deionized water at 50-70°C, stirring until completely dissolved, adding chlorogenic acid and notoginseng saponin, and performing constant temperature stirring, adding genipin solution after cooling, mixing thoroughly, pouring into a mold, and placing in a constant humidity chamber for curing treatment to form a pH / temperature responsive therapeutic layer; (3) applying the indicator layer prepolymer solution to the pH / temperature responsive therapeutic layer by micro-spraying technology, alternately spraying 0.1-1M CaCl2 solution and genipin solution to form a gradient interface, and then subjecting to low-temperature plasma treatment and secondary wet aging to obtain a hydrogel.

[0008] In any of the above technical solutions, in step (2), the spraying volume ratio of the CaCl2 solution to the genipin solution is (2-5):1, and the interval between each spraying is 5-10 minutes.

[0009] In any of the above technical solutions, the duration of low-temperature plasma treatment in step (3) is 30-90 seconds.

[0010] In any of the above technical solutions, the thickness of the surface of the pH / temperature responsive therapeutic layer in step (3) is 180-220 μm.

[0011] In any of the above technical solutions, in step (3), the low-temperature plasma treatment uses argon gas, and the gas flow rate of argon gas is 10-20 sccm, the radio frequency power is 45-50 W, and the treatment distance is 3-6 cm.

[0012] The present invention also provides an application of a hydrogel dressing, wherein any of the above-mentioned double-layer hydrogel dressings is used in the treatment of diabetic wound infection.

[0013] After adopting the technical solution of the present invention, the technical effects that can be achieved are as follows: 1. The visual indicator layer uses the pH color development property of betalain to significantly change the color of the indicator layer (red-purple-brown) at pH 7.0-9.0 on the wound surface, providing medical staff with intuitive infection warning signals, achieving real-time visual monitoring of the wound surface status, and avoiding secondary damage caused by frequent removal and testing of traditional dressings; 2. The therapeutic layer uses the synergistic effect of chlorogenic acid and notoginseng saponins, combined with the pH / temperature dual-responsive drug release characteristics, and the wound infection microenvironment pH increase / local fever triggers the release, achieving precise on-demand drug delivery, improving antibacterial efficiency and reducing drug resistance. The therapeutic layer is a directional porous scaffold (pore size 50-200μm) constructed by a gelatin / carboxymethyl cellulose composite system, which can not only efficiently absorb wound exudate, but its extracellular matrix-like topological structure can also promote fibroblast migration and angiogenesis, accelerate granulation tissue formation, and shorten the healing cycle; 3. Gradient cross-linking interface using Ca 2+ - The alternating cross-linking strategy of genipin combined with low-temperature plasma treatment to form an interpenetrating network structure can enhance the interfacial bonding strength and effectively prevent the risk of delamination of the double-layer structure in a dynamic wound environment; 4. The double-layer independent design avoids interference between the coloring components and the therapeutic components, and the light-proof ultrasonic dispersion process can improve the photostability of betalain. The micro-spraying gradient cross-linking technology combined with low-temperature plasma treatment can achieve precise interface construction while avoiding organic solvent residues, and the entire process adopts an aqueous reaction system, which meets the environmentally friendly production requirements of medical devices; 5. Through the triple innovation of materials, structure and process, the pain points of traditional dressings such as lack of monitoring function, uncontrollable drug release and weak interface bonding have been solved. This dressing is particularly suitable for the treatment of diabetic wound infection, which can effectively relieve wound inflammation, promote wound healing and reduce the recurrence rate of infection. In addition to infection treatment, this dressing can also be applied to other types of chronic wounds and has broad application prospects; 6. All raw materials used are materials with good biocompatibility, non-irritating to wounds, and conducive to wound healing. The preparation method is simple, easy to industrialize, and can meet clinical needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The color change of the hydrogel prepared in Example 1 under different pH conditions; Figure 2 A scanning electron microscope image of the hydrogel therapeutic layer prepared in Example 1; Figure 3 The drug release kinetic curves of the hydrogel prepared in Example 1 under different environmental parameters; wherein A is the change of the cumulative release of chlorogenic acid at 25°C over time, and wherein B is the change of the cumulative release of chlorogenic acid at 37°C over time; Figure 4 The cell compatibility test results of the hydrogel prepared in Example 1; Figure 5 The wound surface changes of diabetic mice in different treatment groups; Figure 6 These are the results of H&E staining in the infection wound experiment in diabetic mice. DETAILED DESCRIPTION

[0015] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0016] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0017] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below.

[0018] Example 1

[0019] (1) Dissolve 3 g of sodium alginate and 5 g of polyvinyl pyrrolidone in 92 mL of deionized water, stir under magnetic stirring at 60 °C for 2 hours until completely dissolved, add 0.3 g of betaine, and disperse under ultrasonication (100 W, 20 minutes) in dark conditions to obtain an indicator layer prepolymer solution; (2) Dissolve 6 g of gelatin and 4 g of carboxymethyl cellulose in 60°C deionized water, stir until completely dissolved, add 0.5 g of chlorogenic acid and 0.3 g of notoginseng saponin, stir at 45°C for 1 hour, cool to 25°C, add 0.3 g of genipin solution, mix thoroughly, pour into a mold, place in a constant humidity chamber, and cure for 24 hours (RH 60%) to form a therapeutic layer; (3) The indicator layer prepolymer liquid was evenly coated on the surface of the therapeutic layer (thickness 200 μm) by micro-spraying technology, and 0.5 mol / L CaCl2 solution (atomization pressure 0.2 MPa) and 0.3 wt% genipin solution were sprayed alternately with a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes each time. Then, low-temperature isopycnic treatment (Ar gas flow rate 15 sccm, RF power 50 W, treatment distance 5 cm, time 60 seconds) was carried out, and secondary wet aging (37 °C, 1 hour, RH 90%) was performed to complete the interfacial interpenetrating network cross-linking and obtain a double-layer hydrogel.

[0020] Example 2

[0021] (1) Dissolve 3 g of sodium alginate and 5 g of polyvinyl pyrrolidone in 92 mL of deionized water, stir under magnetic stirring at 60 °C for 2 hours until completely dissolved, add 0.2 g of betaine, and disperse under ultrasonication (100 W, 20 minutes) in the dark to obtain an indicator layer prepolymer solution; (2) Dissolve 6 g of gelatin and 4 g of carboxymethyl cellulose in 60°C deionized water, stir until completely dissolved, add 0.4 g of chlorogenic acid and 0.3 g of notoginseng saponin, stir at 45°C for 1 hour, cool to 25°C, add 0.3 g of genipin solution, mix thoroughly, pour into a mold, place in a constant humidity chamber, and cure for 24 hours (RH 60%) to form a therapeutic layer; (3) The indicator layer prepolymer liquid was evenly coated on the surface of the therapeutic layer (thickness 180 μm) by micro-spraying technology, and 0.5 mol / L CaCl2 solution (atomization pressure 0.2 MPa) and 0.3 wt% genipin solution were sprayed alternately with a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes each time. Then, low-temperature isopycnic treatment (Ar gas flow rate 15 sccm, RF power 50 W, treatment distance 5 cm, time 60 seconds) was carried out, and secondary wet aging (37 °C, 1 hour, RH 90%) was performed to complete the interfacial interpenetrating network cross-linking and obtain a double-layer hydrogel.

[0022] Example 3

[0023] (1) 3 g of sodium alginate and 5 g of polyvinyl pyrrolidone were dissolved in 92 mL of deionized water, and magnetically stirred at 60°C for 2 hours until completely dissolved. 0.2 g of betaine was added, and ultrasonic dispersion was performed under light-proof conditions (100 W, 20 minutes) to obtain an indicator layer prepolymer solution; (2) Dissolve 6 g of gelatin and 4 g of carboxymethyl cellulose in 60°C deionized water, stir until completely dissolved, add 0.3 g of chlorogenic acid and 0.4 g of notoginseng saponin, stir at 45°C for 1 hour, cool to 25°C, add 0.3 g of genipin solution, mix thoroughly, pour into a mold, place in a constant humidity chamber, and cure for 24 hours (RH 60%) to form a therapeutic layer; (3) The indicator layer prepolymer liquid was evenly coated on the surface of the therapeutic layer (thickness 220 μm) by micro-spraying technology, and 0.5 mol / L CaCl2 solution (atomization pressure 0.2 MPa) and 0.3 wt% genipin solution were sprayed alternately with a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes each time. Then, low-temperature isopycnic treatment (Ar gas flow rate 15 sccm, RF power 50 W, treatment distance 5 cm, time 60 seconds) was carried out, and secondary wet aging (37 °C, 1 hour, RH 90%) was performed to complete the interfacial interpenetrating network cross-linking and obtain a double-layer hydrogel.

[0024] Example 4

[0025] (1) Dissolve 3 g of sodium alginate and 5 g of polyvinyl pyrrolidone in 92 mL of deionized water, stir under magnetic stirring at 60°C for 2 hours until completely dissolved, add 0.4 g of betaine, and disperse under ultrasonication (100 W, 20 minutes) in a dark environment to obtain an indicator layer prepolymer solution; (2) Dissolve 6 g of gelatin and 4 g of carboxymethyl cellulose in 60°C deionized water, stir until completely dissolved, add 0.2 g of chlorogenic acid and 0.3 g of notoginseng saponin, stir at 45°C for 1 hour, cool to 25°C, add 0.3 g of genipin solution, mix thoroughly, pour into a mold, place in a constant humidity chamber, and cure for 24 hours (RH 60%) to form a therapeutic layer; (3) The indicator layer prepolymer liquid was evenly coated on the surface of the therapeutic layer (thickness 200 μm) by micro-spraying technology, and 0.5 mol / L CaCl2 solution (atomization pressure 0.2 MPa) and 0.3 wt% genipin solution were sprayed alternately with a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes each time. Then, low-temperature isopycnic treatment (Ar gas flow rate 15 sccm, RF power 50 W, treatment distance 5 cm, time 60 seconds) was carried out, and secondary wet aging (37 °C, 1 hour, RH 90%) was performed to complete the interfacial interpenetrating network cross-linking and obtain a double-layer hydrogel.

[0026] Example 5

[0027] (1) Dissolve 3 g of sodium alginate and 5 g of polyvinyl pyrrolidone in 92 mL of deionized water, stir under magnetic stirring at 60°C for 2 hours until completely dissolved, add 0.5 g of betaine, and disperse under ultrasonication (100 W, 20 minutes) in a dark environment to obtain an indicator layer prepolymer solution; (2) Dissolve 6 g of gelatin and 4 g of carboxymethyl cellulose in 60°C deionized water, stir until completely dissolved, add 0.1 g of chlorogenic acid and 0.5 g of notoginseng saponin, stir at 45°C for 1 hour, cool to 25°C, add 0.3 g of genipin solution, mix thoroughly, pour into a mold, place in a constant humidity chamber, and cure for 24 hours (RH 60%) to form a therapeutic layer; (3) The indicator layer prepolymer liquid was evenly coated on the surface of the therapeutic layer (thickness 200 μm) by micro-spraying technology, and 0.5 mol / L CaCl2 solution (atomization pressure 0.2 MPa) and 0.3 wt% genipin solution were sprayed alternately with a volume ratio of 3:1. The cycle was repeated 3 times with an interval of 8 minutes each time. Then, low-temperature isopycnic treatment (Ar gas flow rate 15 sccm, RF power 50 W, treatment distance 5 cm, time 60 seconds) was carried out, and secondary wet aging (37 °C, 1 hour, RH 90%) was performed to complete the interfacial interpenetrating network cross-linking and obtain a double-layer hydrogel.

[0028] Comparative Example 1 The hydrogel preparation process is basically the same as that in Example 1, except that chlorogenic acid is not added in step 2, and the prepared hydrogel is not loaded with chlorogenic acid.

[0029] Characterization Processing (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 color observation. Figure 2 As shown in the figure, the material exhibits significant pH-dependent color development properties: it presents a characteristic red color when placed in a simulated normal skin microenvironment (pH 7.0); when placed in a simulated infection environment (pH 8.0-9.0), the material exhibits an obvious purple-red to brown color development response. This gradient color development property originates from the pH-sensitive chromophores introduced into the material, whose maximum absorption wavelength shifts regularly with changes in the pH value of the environment, allowing the hydrogel to indicate the wound healing status in real time through color changes that can be discerned by the naked eye, providing an intuitive visual criterion for early warning of clinical infection.

[0030] (2) The treatment layer sample prepared in Example 1 was freeze-dried and then placed on a vacuum gold spraying stage for gold spraying. Then, a scanning electron microscope (S-4800, Hitachi, Japan) was used to characterize its microstructure. Figure 1As shown in the figure, the sample exhibits a typical hydrogel porous scaffold, presenting a three-dimensional interconnected porous network structure, with pores interconnected through channels to form a continuous three-dimensional framework, and the pore size is evenly distributed between 50-200μm. This optimized multi-level pore structure not only has a large specific surface area, but also can efficiently absorb wound exudate through capillary action. At the same time, the three-dimensional channels provide an ideal channel for oxygen exchange and metabolic product transportation, which meets the structural characteristics of ideal wound dressings.

[0031] (3) In order to systematically evaluate the drug sustained release performance of the hydrogel, the drug sustained release behavior of the chlorogenic acid-loaded hydrogel under different environmental parameters (pH7.2 / 8.2, 25 / 37°C) was studied by UV-visible spectrophotometry. Specifically, the hydrogel sample prepared in Example 1 was placed in a dialysis device containing PBS buffer, and the drug release kinetics were studied under simulated physiological environment (pH7.2, 37°C) and alkaline microenvironment (pH8.2, 25°C). During the experiment, 3 mL of release medium was quantitatively removed at predetermined time intervals, and an isothermal and equal volume of fresh PBS solution was immediately added to maintain a constant volume of the system. The absorbance value was measured at the characteristic absorption wavelength of 330 nm by UV-Vis spectrometer, and the real-time cumulative release of chlorogenic acid was calculated in combination with the pre-established standard curve (R²=0.9992).

[0032] like Figure 3 The drug release kinetics curve shows that environmental parameters have a significant regulatory effect on the drug release behavior of the hydrogel: under the same temperature conditions (37°C), the cumulative release in an alkaline environment (pH8.2) for 48 hours reaches 78.2±2.3%, which is about 1.8 times higher than that in a neutral environment (pH7.2); when the temperature rises from 25°C to 37°C, the drug release rate constant under pH8.2 conditions increases by 1.5 times. The microenvironment of diabetic infection wounds is usually weakly alkaline (pH7.8-8.5) and accompanied by a local temperature increase (37-38°C). The enhanced release effect of this system under such conditions proves that it can intelligently respond to changes in the lesion microenvironment to achieve on-demand drug delivery.

[0033] (4) The antibacterial performance evaluation experiment used the agar plate colony counting method to select Gram-negative Escherichia coli ( Escherichia coli ) and Gram-positive Staphylococcus aureus ( Staphylococcus aureus ) as the model strain. The specific operation is as follows: accurately weigh 0.5 g of the hydrogel sample prepared in Example 1 and mix it with 20 mL of an initial concentration of 1×10 7After the bacterial suspension of CFU / mL is fully mixed, it is transferred to a constant temperature shaking incubator and co-cultured at 37°C and 180rpm for 30 minutes. The cultured bacterial solution is diluted 10 times in series, and 100 μL of the appropriate dilution of the bacterial solution is evenly spread on the LB agar plate, placed in a 37°C constant temperature incubator for 12 hours, and then the colonies are counted. The antibacterial rate is calculated by the formula: Antibacterial rate (%) = (Nc-Ns) / Nc×100%, where Nc is the average colony number of the blank control group, and Ns is the average colony number of the experimental group.

[0034] As shown in Table 1, all hydrogel samples showed significant antibacterial activity. It is particularly noteworthy that the antibacterial efficiency of the example samples against the two test strains was significantly better than that of the comparative example group, and the antibacterial activity increased with the increase of chlorogenic acid concentration.

[0035] Table 1 In vitro antibacterial rate of hydrogel 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 (5) In order to evaluate the biocompatibility of the hydrogel prepared in Example 1, L929 mouse fibroblasts were selected for in vitro cytotoxicity experiments. The specific operation was as follows: a cell culture medium with a density of 1×10 5 A cell suspension of 100 μL cells / mL was inoculated into a 96-well culture plate (100 μL per well) and pre-cultured in a 37°C, 5% CO2 incubator for 24 hours to allow the cells to adhere. Subsequently, the experimental group was replaced with a fresh complete culture medium containing 100 μL of hydrogel extract (prepared according to ISO 10993-12 standard), and the control group was replaced with an equal amount of complete culture medium. After continued culture for 24, 48, and 72 hours, MTT detection was performed at each time point: after discarding the culture medium, 10 μL of MTT working solution (final concentration 0.5 mg / mL) was added to each well, and incubated at 37°C in the dark for 4 hours to allow formazan crystals to form. Subsequently, the supernatant was removed, 100 μL of DMSO was added to dissolve the formazan crystals, and a micro-oscillator was used to gently shake for 10 minutes to ensure full dissolution. Finally, the absorbance value was measured at a wavelength of 570 nm using an enzyme reader, and the cell survival rate was calculated according to the formula: Cell survival rate (%) = (OD value of the experimental group 570 Value / control group OD 570 value) × 100%.

[0036] like Figure 4 As shown, after co-culture for different periods of time, the cell survival rate of the experimental group was always maintained above 95%. This result shows that the prepared hydrogel material did not show obvious cytotoxic effects under in vitro conditions and met the safety standards for biomedical materials.

[0037] (6) Therapeutic effect of the double-layer hydrogel prepared in Example 1 on the treatment of diabetic infected wounds. Eight male KM mice were selected and streptozotocin (STZ) was intraperitoneally injected to establish a type 1 diabetes model (dosage regimen: 50 mg / kg / day, for 5 consecutive days). The effectiveness of the model was verified by a continuous blood glucose monitoring system, and the model success standard was a continuous fasting blood glucose level of ≥11.1 mmol / L. 72 hours after modeling, after isoflurane inhalation anesthesia, an electric shaver was used to shave the hair and iodine was used to disinfect the surgical area. A sterile biopsy punch (diameter 6 mm) was used to construct two circular full-thickness skin defect models symmetrically on both sides of the spine. 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 with PBS buffer (pH 7.4) every day to maintain a moist environment; the wounds of the hydrogel group were evenly covered with the hydrogel prepared in Example 1 (thickness of about 2 mm) after debridement. Both groups of experimental subjects accepted daily dressing changes and systematically recorded the wound healing process. Wound images were collected on days 0, 3, 7, and 14 after surgery.

[0038] Wound healing Figure 5 As shown: the healing speed of the infected wound after the double-layer hydrogel group was significantly faster than that after the PBS buffer (pH 7.4) treatment, indicating that the double-layer hydrogel prepared by the present invention has a good wound healing effect.

[0039] H&E staining histological analysis results (see Figure 6 ) further confirmed the above findings. On the 14th day after surgery, about 40% of the wound surface in the control group was still unclosed, and persistent inflammatory cell infiltration was observed, and the new granulation tissue structure was loose and disordered. In contrast, the wound surface in the hydrogel group had achieved complete re-epithelialization, the epidermis was continuous and complete, the collagen fibers in the dermis were arranged regularly, and the inflammatory cell infiltration phenomenon completely disappeared. Its tissue morphology was highly similar to that of normal skin tissue.

[0040] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A hydrogel dressing with dual response characteristics, characterized in that: Includes the following structures: A visual indicator layer, wherein the visual indicator layer is composed of sodium alginate, polyvinyl pyrrolidone and betalain; pH / temperature responsive therapeutic layer: the pH / temperature responsive therapeutic layer is composed of gelatin, carboxymethyl cellulose, chlorogenic acid, notoginseng saponin and genipin, and the pH / temperature responsive therapeutic layer has a porous scaffold structure; The double-layer hydrogel is connected by a gradient cross-linked interface, wherein the gradient interface is connected by Ca 2+ -Genepin alternating cross-linking strategy and low-temperature plasma treatment formed an interpenetrating network structure.

2. The hydrogel dressing according to claim 1, characterized in that The weight percentage concentrations of the components of the double-layer hydrogel dressing are as follows: The sodium alginate is 1-5wt%, the polyvinyl pyrrolidone is 3-8wt%, the betalain group is 0.1-0.5wt%, the gelatin is 5-7wt%, the carboxymethyl cellulose is 3-5wt%, the chlorogenic acid is 0.1-0.6wt%, the notoginseng saponin is 0.2-0.5wt%, and the genipin is 0.2-0.5wt%.

3. A method for preparing a hydrogel dressing with dual response characteristics, characterized in that: The preparation method is used to prepare the double-layer hydrogel dressing according to any one of claims 1 to 2, comprising the following steps: (1) dissolving the sodium alginate and the polyvinyl pyrrolidone in deionized water, stirring at 50-70° C. for 1-3 hours, adding the betalain, and performing ultrasonic dispersion in the dark to prepare an indicator layer prepolymer solution; (2) dissolving the gelatin and the carboxymethyl cellulose in deionized water at 50-70° C., stirring until completely dissolved, adding the chlorogenic acid and the notoginseng saponin, stirring at a constant temperature, adding the genipin solution after cooling, mixing thoroughly, pouring into a mold, and placing in a constant humidity chamber for curing to form the pH / temperature responsive therapeutic layer; (3) The indicator layer prepolymer liquid is coated on the pH / temperature responsive therapeutic layer by micro-spraying technology, and 0.1-1M CaCl2 solution and the genipin solution are sprayed alternately to form a gradient interface, followed by low-temperature plasma treatment and secondary wet aging to obtain the hydrogel.

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

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

6. The preparation method according to claim 3, characterized in that: The surface thickness of the pH / temperature responsive therapeutic layer 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 gas flow rate of the argon gas is 10-20 sccm, the radio frequency power is 45-50 W, and the treatment distance is 3-6 cm.

8. Application of a hydrogel dressing with dual response characteristics, characterized in that: The double-layer hydrogel dressing as claimed in any one of claims 1 to 2 is used in the treatment of diabetic wound infection.

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