Dressing as well as preparation method and application thereof

Abstract

The invention discloses a dressing for treating chronic skin wounds, and a preparation method of the dressing comprises the following steps: S1, respectively dissolving cobalt nitrate hydrate and 2-methylimidazole in deionized water, then adding a 2-methylimidazole aqueous solution into a cobalt nitrate aqueous solution, and carrying out ultrasonic mixing; s2, adding carbon cloth or gauze into the solution obtained in the S2, shaking to obtain an intermediate product dressing, and cleaning with ethanol; s3, dissolving sodium nitroprusside in an acetic acid aqueous solution, adding the intermediate product obtained in S3 into the acetic acid aqueous solution, shaking until the reaction is finished, washing with ethanol and deionized water respectively, and drying to obtain the dressing. The dressing can catalyze the decomposition of active oxygen without harsh reaction conditions, reduce the expression of inflammatory factors and reduce the inflammation level; the wound angiogenesis can be promoted, and the anoxic environment is improved; the hydrogel can release NO, inhibit growth of bacteria on the wound surface and finally achieve the purpose of promoting effective healing of the chronic wound surface, and meanwhile, the hydrogel is simple in preparation process, mild in reaction condition, easy to synthesize and suitable for popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of metal organic framework materials, and in particular to a dressing for treating chronic skin wounds, and a preparation method and application thereof. Background Art

[0002] Chronic wounds refer to wounds that last for more than two weeks or that cannot heal naturally for some reason, mainly including diabetic foot ulcers, venous ulcers, pressure sores, surgical wounds, etc. Under normal circumstances, acute wounds go through the healing stage in a normal and timely manner, but due to factors such as wound size, depth, location, patient age, and local and systemic diseases, chronic wounds fail to complete repair in the normal order and time or fail to restore normal anatomy and function. According to reports, the characteristics of chronic wounds are mainly manifested as chronic inflammation, hypoxia, poor cytokine environment and bacterial colonization, with elevated levels of inflammatory cytokines and proteases, which damage important extracellular matrix components, growth factors and growth factor receptors.

[0003] Chronic wounds bring heavy disease burden and economic burden to patients and society. For example, patients with diabetic foot ulcers have a lifetime incidence ranging from 15% to 25%, and severe diabetic foot patients need amputation. In the delayed healing of diabetic wounds, activation of oxidative stress pathways, bacterial colonization, impaired angiogenesis and hypoxia play an important role. Lack of oxygen and nutrients, accumulation of reactive oxygen species, and bacterial biofilm further hinder wound healing. At present, there are several types of dressings used for skin wound debridement in clinical practice. First, traditional dressings such as gauze and bandages made of natural cotton or synthetic fibers are widely used in wound dressing changes to cover and protect wounds from contamination or stop bleeding. The function is relatively simple, and the gauze after adsorbing secretions is easy to stick to the wound. Secondly, film dressings, foam dressings, hydrogel excipients, etc. Although these dressings can create a moist environment, they cannot play a targeted role in the oxidative stress state and bacterial colonization that may exist in clinical skin wounds. Non-specific treatment methods make most diabetic foot patients unable to achieve clinical cure and the disease is prolonged.

[0004] Metal-Organic Frameworks (MOFs) are organic-inorganic hybrid materials with intramolecular pores formed by self-assembly of organic ligands and metal ions or clusters through coordination bonds. It is a class of highly active and selective catalysts, and the function of MOF can be designed by selecting different metal ions and ligands according to their own needs. With the advancement of technology, MOF is widely used in medicine, biology and chemistry due to its high stability and good catalytic activity. Sodium nitroprusside (SNP) is a clinical drug that can release NO in the body, promote angiogenesis, and kill bacteria in wounds. Cobalt (Co) is an essential trace element for the human body with good biosafety. Metal cobalt ions (Co 2+ ) can not only inhibit bacterial growth, but also stabilize HIF-1α and promote wound angiogenesis. 2+ As a metal center, SNP was used as a ligand to synthesize a MOF structure similar to Prussian blue, which has strong enzymatic activity.

[0005] This kind of MOF can be grown in situ on some flat macroscopic carriers to synthesize different MOF dressings. The dressing can also absorb wound exudate for skin wound healing. Medical absorbent gauze has good moisture absorption and moisture dissipation properties and is suitable as a base material for medical bandages and dressings. Carbon fiber cloth, also known as carbon cloth, has high strength, low density, thin thickness, high durability, will not rust, and has rich surface active sites. The inventors used medical absorbent gauze and carbon cloth as macroscopic carriers to synthesize this kind of dressing. While killing bacteria, it promotes angiogenesis, absorbs wound exudate, and promotes skin wound healing. Based on the above situation, the inventors have developed a MOF that can be grown in situ on a macroscopic carrier. The macroscopic dressing after the reaction promotes skin wound healing. At present, there are no reports on the preparation and application of this kind of dressing. Summary of the invention

[0006] The present invention provides a dressing for treating chronic skin wounds, a preparation method and an application thereof, aiming to solve the problems existing in the above-mentioned background technology.

[0007] In order to achieve the above technical objectives, the present invention mainly adopts the following technical solutions: One of the purposes of the present invention is to provide a dressing for treating chronic skin wounds and a preparation method thereof, comprising the following steps: S1: Cobalt nitrate hydrate [Co(NO 3 ) 2 .xH 2 O] and 2-methylimidazole (2-MI) were dissolved in deionized water, respectively, and then the 2-methylimidazole aqueous solution was added to the cobalt nitrate aqueous solution and ultrasonicated until the mixture was uniformly mixed; S2: Add carbon cloth or gauze to the solution obtained in S2 and shake until the reaction is completely completed to obtain an intermediate dressing, which is then washed with ethanol; S3: Dissolve sodium nitroprusside sodium (SNP) in aqueous acetic acid solution, add the intermediate product obtained in S3, shake until the reaction is completed, wash with ethanol and deionized water respectively, and dry to obtain the final product dressing.

[0008] In step S1, the cobalt nitrate hydrate [Co(NO 3 ) 2 .xH 2 O] has a mass of 175 to 700 mg, and a mass of 2-methylimidazole has a mass of 0.4 to 1.6 g; in step S2, the area of ​​the carbon cloth or gauze has a mass of 25 to 100 cm 2 ; In step S3, the mass of the sodium nitroprusside is 20 to 80 mg.

[0009] In steps S2 and S3, the ethanol is anhydrous ethanol or ethanol with a mass fraction of 95%.

[0010] In step S3, the concentration of the acetic acid aqueous solution is 1-4 mM.

[0011] In step S1, the ultrasonic time is 2 to 10 minutes; in step S2, the reaction time is 2 to 3 hours; in step S3, the reaction time is 1 to 2 hours.

[0012] In step S3, the drying method is freeze-drying or vacuum drying, and the time taken is 1 to 2 days.

[0013] The length of the sheet structure grown on the dressing is 0.5 to 1.5 µm.

[0014] Application of dressings in the preparation of materials for treating chronic skin wounds.

[0015] As one of the embodiments of the present invention, in step S1, the cobalt nitrate hydrate [Co(NO 3 ) 2 .xH 2 O] has a mass of 175 to 700 mg, and a mass of 2-methylimidazole of 0.4 to 1.6 g; the area of ​​the carbon cloth or gauze in step S2 is 25 to 100 cm 2 ; In step S3, the mass of the sodium nitroprusside is 20 to 80 mg.

[0016] As one of the embodiments of the present invention, in step S3, the ethanol is anhydrous ethanol or ethanol with a mass fraction of 95%.

[0017] As one of the embodiments of the present invention, in step S3, the concentration of the acetic acid aqueous solution is 1-4 mM.

[0018] As one of the embodiments of the present invention, in step S1, the ultrasonic time is 2 to 10 minutes; in step S2, the reaction time is 2 hours to 3 hours; in step S3, the reaction time is 1 hour to 2 hours.

[0019] As one of the embodiments of the present invention, in step S3, the drying method is freeze-drying or vacuum drying, and the time taken is 1 to 2 days.

[0020] The second object of the present invention is to provide a dressing for treating chronic skin wounds, which is mainly prepared by the preparation method of the dressing for treating chronic skin wounds as described above.

[0021] Preferably, the length of the sheet structure grown on the dressing is 0.5 to 1.5 µm.

[0022] The third object of the present invention is to provide a dressing prepared by the preparation method of the dressing for treating chronic skin wounds as described above, or the use of the dressing for treating chronic skin wounds as described above in the preparation of materials for treating chronic skin wounds.

[0023] Compared with the prior art, the present invention mainly has the following beneficial effects: (1) The present invention adopts a new in situ synthesis method to synthesize a dressing for treating chronic skin wounds. The length of the sheet structure grown on the dressing is 0.5 to 1.5 µm, and the biocompatibility is high. The dressing does not require harsh reaction conditions to catalyze the reactive oxygen species (H 2 O 2 It can decompose inflammatory factors, reduce the expression of inflammatory factors, and lower the level of inflammation; it can promote angiogenesis in the wound and improve the hypoxic environment; it can release NO and inhibit the growth of bacteria in the wound, and ultimately achieve the purpose of promoting the effective healing of chronic skin wounds, providing a new treatment method for promoting the healing of clinical chronic skin wounds.

[0024] (2) The preparation process disclosed in the present invention is simple, the reaction conditions are mild, and the synthesis is easy, thus being suitable for popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Optical images of the CoSNP@CFC dressing and CoSNP@Gauze dressing of the present invention; Figure 2 This is a scanning electron micrograph of the CoSNP@CFC dressing of the present invention; Figure 3 This is the X-ray diffraction pattern of the CoSNP@CFC dressing of the present invention; Figure 4This is a scanning electron micrograph of the CoSNP@Gauze dressing of the present invention; Figure 5 This is the X-ray photoelectron spectrum of the CoSNP@Gauze dressing of the present invention; Figure 6 The CoSNP@CFC dressing of the present invention degrades H 2 O 2 rate; Figure 7 The CoSNP@CFC dressing of the present invention degrades H 2 O 2 Produce O 2 rate; Figure 8 The CoSNP@Gauze dressing of the present invention degrades H 2 O 2 rate; Fig. 9 The CoSNP@Gauze dressing of the present invention degrades H 2 O 2 Produce O 2 rate; Fig.10 This is a fluorescence image of the CoSNP@CFC dressing of the present invention clearing intracellular reactive oxygen species ROS; Fig.11 This is a fluorescence image of the CoSNP@Gauze dressing of the present invention clearing intracellular reactive oxygen species ROS; Fig.12 This is a statistical diagram of the healing area of ​​skin wounds in diabetic mice treated with the CoSNP@CFC dressing of the present invention; Fig.13 This is the H&E staining image of the skin wound tissue of diabetic mice treated with the CoSNP@CFC dressing of the present invention; Fig.14 This is a graph showing the results of an in vitro cytotoxicity test of the CoSNP@CFC dressing of the present invention; Fig.15 H&E staining of the main visceral organ sections of mice treated with the CoSNP@CFC dressing of the present invention; Fig.16 This is a graph showing the results of an in vitro cytotoxicity experiment of the CoSNP@Gauze dressing of the present invention. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to these embodiments. Example 1

[0027] 700 mg of cobalt nitrate hydrate [Co(NO 3 ) 2 .6H 2O] and 1.6 g 2-Methylimidazole (2-MI) were dissolved in 100 mL deionized water and mixed by ultrasonication for 10 min. 2 The carbon cloth was added to the solution and reacted for 3 hours to obtain an intermediate product, which was then washed with anhydrous ethanol. 80 mg of sodium nitroprusside (SNP) was dissolved in a 1 mM acetic acid aqueous solution, and the intermediate product was added to the solution under shaking for 2 hours, washed with anhydrous ethanol and deionized water, respectively, and dried to obtain the final product dressing, that is, the diabetic dressing CoSNP@CFC of the present invention was obtained. The optical actual picture is shown in the attached figure. Figure 1 shown. Example 2

[0028] 180 mg of cobalt nitrate hydrate [Co(NO 3 ) 2 .6H 2 O] and 0.4 g 2-Methylimidazole (2-MI) were dissolved in 20 mL deionized water, and mixed by ultrasonic for 3 min. 2 Gauze was added to the solution and reacted for 2 hours to obtain an intermediate product, which was then washed with anhydrous ethanol. 25 mg of sodium nitroprusside (SNP) was dissolved in a 2 mM acetic acid aqueous solution, and the intermediate product was added to the solution under shaking for 1 hour, washed with anhydrous ethanol and deionized water, respectively, and dried to obtain the final product dressing, that is, the diabetic dressing CoSNP@Gauze of the present invention was obtained. The optical actual picture is shown in the attached figure. Figure 1 shown. Example 3

[0029] 600 mg of cobalt nitrate hydrate [Co(NO 3 ) 2 .6H 2 O] and 9 g 2-Methylimidazole (2-MI) were dissolved in 150 mL deionized water, stirred at room temperature for 20 min to obtain an intermediate product, washed with anhydrous ethanol and deionized water, and freeze-dried; 40 mg of the intermediate product and 90 mg of sodium nitroprusside (SNP) were dissolved in 30 mL anhydrous ethanol and 10 mL 10 mM acetic acid aqueous solution, respectively, ultrasonically mixed and mixed, stirred at room temperature for 2 h, the product was washed with ethanol and deionized water several times, and freeze-dried to obtain the final product, that is, the powder CoSNP in the present invention was obtained. Example 4

[0030] Example 1 Characterization of the CoSNP@CFC dressing prepared 1) Scanning electron microscopy experiment of CoSNP@CFC dressing Take 1cm 2 The dressing CoSNP@CFC was placed on a silicon wafer soaked in alcohol and dried in an electron drying oven to prepare a scanning electron microscope (SEM) sample.

[0031] The results observed by scanning electron microscopy are shown in the attached Figure 2 As shown, the length of the lamellar structure grown on the dressing is 0.5 to 1.5 µm.

[0032] 2) X-ray diffraction experiment of CoSNP@CFC dressing The synthesized dressing CoSNP@CFC was subjected to X-ray diffraction experiment. The results are shown in the attached figure. Figure 3 As shown, the MOF on the dressing has a crystalline structure. Example 5

[0033] Example 2 Characterization of the prepared dressing CoSNP@Gauze 1) Scanning electron microscopy experiment of CoSNP@Gauze dressing Take 1cm 2 The dressing CoSNP@Gauze was placed on a silicon wafer soaked in alcohol and dried in an electron drying oven to prepare a scanning electron microscope (SEM) sample.

[0034] The results observed by scanning electron microscopy are shown in the attached Figure 4 As shown, the length of the lamellar structure grown on the dressing is 0.5 to 1.5 µm.

[0035] 2) X-ray photoelectron spectroscopy experiment of CoSNP@Gauze dressing The synthesized dressing CoSNP@Gauze was subjected to X-ray photoelectron spectroscopy experiments. The results are shown in the attached figure. Figure 5 As shown, Co, Fe and N elements were added to the dressing after the reaction. Example 6

[0036] Example 1: The prepared dressing CoSNP@CFC degrades H 2 O 2 Condition 1) Dressing CoSNP@CFC degradation of H 2 O 2 rate Take the synthesized dressing CoSNP@CFC, weigh it and add 1mM H 2 O 2 The control group was an equal volume of H 2 O 2The remaining H was detected by UV-visible photometer after 0, 10, 20, 30, 40, 50, 60, 80, 100, and 120 min of reaction. 2 O 2 Concentration, the results are as attached Figure 6 As shown, the prepared dressing has a rapid H 2 O 2 Catalytic ability.

[0037] 2) Dressing CoSNP@CFC degradation of H 2 O 2 Produce O 2 rate Take the synthesized dressing CoSNP@CFC, weigh it and add 1mM H 2 O 2 The control group was an equal volume of H 2 O 2 . Use a dissolved oxygen meter to monitor H 2 O 2 Liquid decomposition produces O 2 The results are shown in the attached Figure 7 As shown in Figure 2, the prepared dressing can catalyze H 2 O 2 Liquid decomposes quickly to produce O 2 . Example 7

[0038] Example 2 The prepared dressing CoSNP@Gauze degrades H 2 O 2 Condition 1) Dressing CoSNP@Gauze degrades H 2 O 2 rate Take the synthesized dressing CoSNP@Gauze, weigh it and add it to 10mM H 2 O 2 The control group was an equal volume of H 2 O 2 The remaining H was detected by UV-visible photometer after 0, 5, 10, 15, 20, 30, 40, 50, 60, 80, 100, and 120 min of reaction. 2 O 2 Concentration, the results are as attached Figure 8 As shown, the prepared dressing has a rapid H 2 O 2 Catalytic ability.

[0039] 2) Dressing CoSNP@Gauze degrades H 2 O 2Produce O 2 rate Take the synthesized dressing CoSNP@Gauze, weigh it and add 1mM H 2 O 2 The control group was an equal volume of H 2 O 2 . Use a dissolved oxygen meter to monitor H 2 O 2 Liquid decomposition produces O 2 The results are shown in the attached Fig. 9 As shown in Figure 2, the prepared dressing can catalyze H 2 O 2 Liquid decomposes quickly to produce O 2 . Example 8

[0040] Example 1 Determination of the removal of intracellular reactive oxygen species by the prepared dressing CoSNP@CFC The DCF method is used to measure intracellular ROS. DCFH-DA itself has no fluorescence and can freely pass through the cell membrane. After entering the cell, it can be hydrolyzed by the esterase in the cell to produce DCFH. However, DCFH cannot penetrate the cell membrane, so the probe can be easily loaded into the cell. The reactive oxygen ROS in the cell can oxidize the non-fluorescent DCFH to produce fluorescent DCF. Therefore, the level of reactive oxygen in the cell can be known by detecting the fluorescence of DCF.

[0041] First, human umbilical vein endothelial cells Huvec were seeded in a 24-well plate, with 50,000 cells per well. 2 O 2 group, CFC group, CFC+200 µM H 2 O 2 group, CoSNP@CFC group, and CoSNP@CFC+200 µM H 2 O 2 Group. 24 hours after cell inoculation, the cells were treated according to the above grouping, washed twice with sterile PBS solution, and replaced with DCFH-DA (Sigma) with a final concentration of 10μM in an incubator for 30 min. After staining, the cells were observed under a fluorescence microscope. The results are shown in the attached figure. Fig.10 As shown, CoSNP@CFC dressing can decompose H 2 O 2 Remove reactive oxygen species and protect cells from damage by reactive oxygen species. Example 9

[0042] Example 2 Determination of the removal of intracellular reactive oxygen species by the prepared dressing CoSNP@Gauze First, human umbilical vein endothelial cells Huvec were seeded in a 24-well plate, with 50,000 cells per well. 2 O 2 group, CoSNP@Gauze group and CoSNP@Gauze+100 µM H 2 O 2 Group. 24 hours after cell inoculation, the cells were treated according to the above grouping, washed twice with sterile PBS solution, and replaced with DCFH-DA (Sigma) with a final concentration of 10μM in an incubator for 30 min. After staining, the cells were observed under a fluorescence microscope. The results are shown in the attached figure. Fig.11 As shown, CoSNP@Gauze dressing can decompose H 2 O 2 Remove reactive oxygen species and protect cells from damage by reactive oxygen species. Example 10

[0043] Example 1 In vivo test on the healing of diabetic mice skin wounds treated with the prepared CoSNP@CFC dressing 1) Establishment of diabetic mouse skin wound model In order to study the effect of CoSNP@CFC dressing on the healing of diabetic mouse skin wounds, the internationally common diabetic mouse skin wound model was first established. Diabetic mice (male, BALB / c) were induced by intraperitoneal injection of streptozotocin (STZ, 120 mg / kg) once a week until the blood glucose level was stable above 16.8 mM / L for two consecutive weeks. The diabetic mice were anesthetized with 10% diluted sodium pentobarbital solution (10 mg / ml), and the back of the diabetic mice was prepared for hair removal of 3×4 cm, disinfected with 75% alcohol and iodine, and a circular full-thickness skin defect with a diameter of 10 mm was made on the back using a punch to form a wound.

[0044] 2) CoSNP@CFC dressings for treating skin wounds in diabetic mice During the modeling process, the postoperative mice were randomly divided into 3 groups (Control group, CFC group, CoSNP@CFC group), with 10 mice in each group. The wound was photographed with a camera and recorded as day 0. The wounds were treated with dressings respectively, while the Control group was not treated. The wounds were then wrapped with medical gauze. Wound photos were taken on days 3, 7, 10, and 14, and the wound area was calculated using ImageJ software. The final healing rate is shown in the attached figure. Fig.12 As shown in the figure, the differences in the healing area of ​​diabetic wounds in the CoSNP@CFC group, the Control group and the CFC group were statistically significant. Fig.13The H&E staining of the tissue is shown. H&E is mainly used to observe the pathological morphology of tissue. The figure shows that the CoSNP@CFC dressing group has more angiogenesis and good wound healing. The above results reflect that CoSNP@CFC dressing can effectively promote the healing of skin wounds in diabetic mice. Embodiment 11

[0045] Example 1 Safety evaluation of the CoSNP@CFC dressing prepared 1) Cytotoxicity assay In this experiment, flow cytometry analysis was used to investigate the toxicity of CoSNP@CFC on human umbilical vein endothelial cells. First, 150,000 cells were added to each of the 6 wells and cultured for 24 hours to allow them to adhere to the wall. The CoSNP@CFC dressing was added to the culture medium and cultured for 24 hours. The upper culture medium was discarded, the cells were digested with trypsin, collected, washed twice with sterile PBS, and then tested using an apoptosis detection kit. Fig.14 As shown in the figure, the cell viability of human umbilical vein endothelial cells was still above 90% after 24 hours of incubation, which was no different from the control group. This indicates that the cytotoxicity of CoSNP@CFC dressing is low.

[0046] 2) Visceral safety evaluation After the CoSNP@CFC dressing was embedded in the mouse body for 7 days, the mouse was euthanized and the main internal organs (heart, liver, spleen, lung, and kidney) of the mouse were taken for H&E staining to analyze whether the CoSNP@CFC dressing was toxic to the mouse internal organs. Fig.15 Shown is the H&E staining of the main organs in the CoSNP@CFC dressing group, which showed no obvious histomorphological differences compared with healthy mice, which further confirmed the low in vivo toxicity of the CoSNP@CFC dressing and its good biocompatibility.

[0047] Example 12

[0048] Example 2 Safety evaluation of the prepared CoSNP@Gauze dressing In this experiment, CCK-8 was used to determine the toxicity of CoSNP@Gauze to human umbilical vein endothelial cells. Cell Counting Kit-8 is a rapid, highly sensitive kit based on WST-8 and widely used for cell activity and cytotoxicity detection. First, 20,000 cells were added to each well of 24 wells and cultured for 24 hours to allow them to adhere to the wall. CoSNP@Gauze dressings were added to the culture medium and cultured for 24 hours. The upper culture medium was discarded, washed twice with sterile PBS, and replaced with serum-free culture medium with a final concentration of 10% CCK-8 for incubation for 1 hour. The absorbance at 540nm was measured using an enzyme reader. The results are shown in the attached figure. Fig.16As shown in the figure, the cell viability of human umbilical vein endothelial cells was still above 90% after 24 hours of incubation, which was no different from the control group. This indicates that the cytotoxicity of CoSNP@Gauze dressing is low.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multifunctional dressing, comprising the following steps: S1: Dissolve cobalt nitrate hydrate [Co(NO3)2.xH2O] and 2-methylimidazole in deionized water respectively, then add the 2-methylimidazole aqueous solution to the cobalt nitrate aqueous solution, and sonicate until the mixture is uniform; S2: Add carbon cloth or gauze to the solution obtained in S1 and shake until the reaction is completely completed to obtain an intermediate product, which is then washed with ethanol; S3: dissolving sodium nitroprusside in aqueous acetic acid solution and adding the intermediate product obtained in S2 thereto, The mixture was shaken until the reaction was complete, washed with ethanol and deionized water, and dried to obtain the final dressing.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass of the cobalt nitrate hydrate [Co(NO3)2.xH2O] is 175-700 mg, the concentration of the cobalt nitrate aqueous solution is 17.5-35 g / L, the mass of the 2-methylimidazole is 0.4-1.6 g, and the concentration of the 2-methylimidazole aqueous solution is 40-80 g / L; in step S2, the area of ​​the carbon cloth or gauze is 25-100 cm 2 .

3. The preparation method according to claim 1, characterized in that: In steps S2 and S3, the ethanol is anhydrous ethanol or ethanol with a mass fraction of 95%.

4. The preparation method according to claim 1, characterized in that: In step S3, the concentration of the acetic acid aqueous solution is 1-4 mM, the mass of the sodium nitroprusside is 20-80 mg, and the concentration of the sodium nitroprusside after being dissolved in the acetic acid aqueous solution is 4.5-9 g / L.

5. The preparation method according to claim 1, characterized in that: In step S1, the ultrasonic time is 2 to 10 minutes; in step S2, the reaction time is 2 to 3 hours; in step S3, the reaction time is 1 to 2 hours.

6. The method for preparing a dressing according to claim 1, characterized in that: In step S3, the drying method is freeze-drying or vacuum drying, and the time taken is 1 to 2 days.

7. A dressing, characterized in that: The method is described in any one of claims 1 to 6.

8. The dressing according to claim 7, characterized in that: The length of the sheet structure grown on the dressing is 0.5 to 1.5 µm.

9. Use of the dressing according to any one of claims 7 or 8 in preparing materials for treating chronic skin wounds.

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