Nanofiber functional dressing for wound healing of burns and scalds

Abstract

The invention discloses a nanofiber functional dressing for wound healing of burns and scalds, and belongs to the technical field of wound repairing dressings. The dressing is prepared through double-layer electrostatic spinning and comprises a hydrophilic nanofiber layer and a hydrophobic nanofiber layer. The hydrophobic nanofiber layer is prepared by electrostatic spinning of an antibacterial composite modified material and isocyanate-terminated oligomeric lactic acid, and the antibacterial composite modified material is prepared by acylating chlorination of (9I)-2, 4, 8, 10-tetraoxaspiro [5.5] undecane-3, 9-dipropionic acid, reaction of the acylating chlorination product and N, N-bis (2-benzimidazole methyl) amine, and quaternization of benzyl chloride. The tetrooxaspiro rigid structure improves the thermal stability and inhibits the molecular chain from absorbing water and expanding; the quaternized benzimidazole group destroys cell membranes through positive charges, and can efficiently resist bacteria. An amido bond in the hydrophilic layer and a urea bond formed by the antibacterial material and an isocyanate group remarkably improve the liquid absorption capacity; the hydrophobic layer provides mechanical support and ductility; two layers of interfaces are fused through heat treatment, the overall tearing strength is improved, and the joint movement requirement is met.

Description

Technical Field

[0001] The invention belongs to the technical field of wound repair dressings, and in particular relates to a nanofiber functional dressing for healing burn and scald wounds. Background Art

[0002] Burns and scalds are common skin tissue injuries, with the following notable wound characteristics: severe damage or even loss of the skin barrier, leading to massive exudation of tissue fluid; the wound environment is highly susceptible to the growth of pathogens such as bacteria and fungi, causing infection; and the activity of endogenous enzymes and growth factors in the damaged tissue is suppressed, slowing the healing process. Therefore, an ideal burn and scald dressing must possess multiple functions: efficient absorption of exudate to maintain a moderately moist microenvironment, strong and long-lasting antimicrobial protection, good biocompatibility, appropriate mechanical strength, and a stable physicochemical structure.

[0003] A wide variety of dressings are currently in clinical use, but they still have numerous limitations. Traditional dressings (such as gauze) have limited fluid absorption capacity, are prone to adhesion to the wound surface, causing secondary damage, and have insufficient antimicrobial properties. While hydrogel dressings can provide a moist environment, they generally have poor mechanical strength, are easily damaged, and lack the ability to manage wounds with high exudate volumes. For example, Chinese invention patent application number 201210444974.X discloses an antimicrobial dressing for deep, infected wounds. Its core antimicrobial ingredient is nanosilver. While nanosilver has a broad antimicrobial spectrum, it carries the risk of nanosilver particles aggregating, leading to decreased antimicrobial efficacy, and may be absorbed and deposited by the body with long-term use, potentially causing biotoxicity. Furthermore, many existing dressings struggle to simultaneously achieve excellent fluid absorption capacity, robust antimicrobial activity, good mechanical support, and flexibility. Therefore, the development of a new functional dressing is crucial for promoting rapid and safe healing of burn wounds, reducing the risk of infection, and improving patient outcomes. Summary of the Invention

[0004] In view of the above situation, in order to overcome the defects of the existing technology, the present invention provides a nanofiber functional dressing with high-efficiency liquid absorption capacity, long-lasting and strong antibacterial properties, excellent mechanical strength and good biocompatibility, so as to effectively solve the limitations of existing burn and scald dressings in terms of liquid absorption capacity, antibacterial effect, mechanical support and safety, thereby accelerating the healing process of burn and scald wounds, reducing the risk of infection and improving the quality of healing.

[0005] In order to achieve the above object, the following technical solution is adopted: The present invention provides a nanofiber functional dressing for burn and scald wound healing, which is prepared by the following steps: S1, mixing an antibacterial composite modified material and an isocyanate-terminated oligolactic acid in a mass ratio of 1:1-3, dissolving the mixture in a mixed solvent of chloroform and N,N-dimethylacetamide in a volume ratio of 3-5:1 to form a first spinning solution with a total solid content of 10-20 wt%, and electrospinning the first spinning solution to obtain a hydrophilic nanofiber layer; S2. Dissolve polycaprolactone in a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3-5:1 to form a second spinning solution with a mass concentration of 8-15wt%. Electrospin the second spinning solution on the surface of the hydrophilic nanofiber layer to form a hydrophobic nanofiber layer covering the hydrophilic nanofiber layer to form a double-layer structure. Then, heat treat the mixture at 50-70°C for 8-24h to obtain a nanofiber functional dressing.

[0006] Furthermore, the antibacterial composite modified material is prepared by the following steps: (1) Under nitrogen protection, (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid was dissolved in anhydrous dichloromethane, then cooled to 0-5°C, and a mixed solution of thionyl chloride and N,N-dimethylformamide was slowly added dropwise. After the addition was complete, the temperature was raised to 20-30°C and the reaction was continued for 3-6 hours. The solvent and excess thionyl chloride were removed by distillation under reduced pressure to obtain intermediate A. (2) Dissolve intermediate A in dichloromethane, cool to 0-5°C, and add dropwise an anhydrous tetrahydrofuran solution containing N,N-bis(2-benzimidazolemethyl)amine and triethylamine. After the addition is complete, heat to 50-70°C and reflux for 10-15 hours. Then cool to room temperature, add water to precipitate the solid, filter, and wash with cold water to obtain intermediate B. (3) Add intermediate B and potassium carbonate to N,N-dimethylformamide, stir at 50-80°C for 0.5-2h, slowly add benzyl chloride, continue the reaction for 20-30h, cool to room temperature, filter to remove solids, pour the filtrate into 3-5 times the volume of ethanol for precipitation, collect the precipitate and wash it with ethanol three times, dissolve the product in deionized water, dialyze using a dialysis bag with a molecular weight cutoff of 3000-5000Da for 40-50h, and freeze-dry to obtain an antibacterial composite modified material.

[0007] Furthermore, in step (1), the feeding ratio of (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid, dichloromethane, thionyl chloride, and N,N-dimethylformamide is 8-12 g: 120-150 mL: 50-80 mL: 0.3-0.5 mL.

[0008] Furthermore, in step (2), the feed ratio of intermediate A, dichloromethane, N,N-bis(2-benzimidazolemethyl)amine, triethylamine, and anhydrous tetrahydrofuran is 8-15 g: 200-220 mL: 5.2-7.5 g: 10-15 mL: 10-20 mL.

[0009] Furthermore, in step (3), the feed ratio of intermediate B, potassium carbonate, N,N-dimethylformamide, and benzyl chloride is 7-10 g: 120-150 mL: 4.2-6 g.

[0010] Furthermore, the isocyanate-terminated oligolactic acid in step S1 is hexamethylene diisocyanate-terminated oligolactic acid, with a number average molecular weight of 2000-5000 Da and an isocyanate group content of 1.0-3.0 wt %.

[0011] Furthermore, in step S2, the number average molecular weight of the polycaprolactone is 50,000-100,000 Da, the thickness of the hydrophobic nanofiber layer is 100-300 μm, and the thickness of the hydrophilic nanofiber layer is 50-150 μm.

[0012] Furthermore, in step S1, the spinning voltage is 12-18 kV, the receiving distance is 10-20 cm, the flow rate is 0.3-1.0 mL / h, and the ambient humidity is ≤40%.

[0013] Furthermore, in step S2, the spinning voltage is 15-20 kV, the receiving distance is 15-25 cm, the flow rate is 0.8-1.5 mL / h, and the ambient humidity is ≤40%.

[0014] The beneficial effects of the present invention are: The central secondary amine nitrogen in the antibacterial composite modified material reacts with chlorinated (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid. The rigid structure of the tetraoxaspiro ring significantly improves the thermal stability and spatial orientation of the molecular chain, restricts the flexible movement of the molecular chain, reduces the disordered entanglement of the polymer chain during the electrospinning process, ensures the uniformity of the material structure, and inhibits the transitional expansion of the molecular chain after water absorption through the rigid skeleton. The benzimidazole group itself has antibacterial activity. After the benzyl chloride quaternization reaction, it forms a quaternary ammonium salt structure with a strong positive charge, which can destroy the integrity of the cell membrane and show high antibacterial properties against Staphylococcus aureus, Escherichia coli, and Candida albicans, effectively preventing wound infection. The secondary amine group of the benzimidazole ring in the antibacterial composite modified material reacts with the isocyanate group of the isocyanate-terminated oligolactic acid to form a stable urea group, which is then electrospun into a hydrophilic nanofiber layer. The abundant hydrophilic amide bonds in the molecular chain significantly increase the water absorption rate of the dressing, efficiently absorbing wound tissue fluid and maintaining a moist healing environment. The hydrophobic nanofiber layer provides high ductility and mechanical support, blocking external pathogens. The hydrophilic nanofiber layer ensures biocompatibility, quickly absorbs fluid and reduces wound exudation. The interface between the two layers is fused through heat treatment to improve the overall tear resistance of the dressing, adapting to the use requirements of active parts such as joints. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a bar graph showing the tensile strength test results of the nanofiber functional dressings of Examples 1-3 of the present invention and Comparative Example 1; Figure 2 This is a bar graph showing the cytotoxicity test results of the nanofiber functional dressings of Examples 1-3 of the present invention and Comparative Example 1; Figure 3 This is a bar chart of the antibacterial test results of the nanofiber functional dressings of Examples 1-3 of the present invention and Comparative Example 1; Figure 4 This is a diagram showing the wound state of the nanofiber functional dressing of Example 3 of the present invention in a burn wound healing experiment in rats.

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0019] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and the experimental materials used in the following examples, unless otherwise specified, are all purchased from commercial channels.

[0020] Example 1: A functional nanofiber dressing for burn and scald wound healing is prepared by the following steps: S1, mixing an antibacterial composite modified material and an isocyanate-terminated oligolactic acid in a mass ratio of 1:1, dissolving the mixture in a mixed solvent of chloroform and N,N-dimethylacetamide in a volume ratio of 3:1 to form a first spinning solution with a total solid content of 10 wt%, and electrospinning the first spinning solution to obtain a hydrophilic nanofiber layer; S2. Dissolve polycaprolactone in a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 to form a second spinning solution with a mass concentration of 8 wt%. Electrospin the second spinning solution on the surface of the hydrophilic nanofiber layer to form a hydrophobic nanofiber layer covering the hydrophilic nanofiber layer to form a double-layer structure. The resulting mixture is heat-treated at 50°C for 8 h to obtain a nanofiber functional dressing.

[0021] The antibacterial composite modified material is prepared by the following steps: (1) Under nitrogen protection, 8 g of (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid was dissolved in 120 mL of anhydrous dichloromethane, cooled to 0°C, and a mixed solution consisting of 50 mL of thionyl chloride and 0.3 mL of N,N-dimethylformamide was slowly added dropwise. After the addition was complete, the temperature was raised to 20°C and the reaction was continued for 3 h. The solvent and excess thionyl chloride were removed by distillation under reduced pressure to obtain intermediate A. (2) Dissolve 8 g of intermediate A in 200 mL of dichloromethane, cool to 0 ° C, and add dropwise a solution containing 5.2 g of N, N-bis (2-benzimidazolemethyl) amine, 10 mL of triethylamine and 10 mL of anhydrous tetrahydrofuran. After the addition is complete, heat to 50 ° C and reflux for 10 h. Cool to room temperature, add water to precipitate the solid, filter, and wash with cold water to obtain intermediate B. (3) 7 g of intermediate B and 4.2 g of potassium carbonate were added to 120 mL of N,N-dimethylformamide, stirred at 50 °C for 0.5 h, 4.2 g of benzyl chloride was slowly added, and the reaction was continued for 20 h. The mixture was cooled to room temperature, filtered to remove the solid, and the filtrate was poured into 3 times the volume of ethanol for precipitation. The precipitate was collected and washed with ethanol 3 times. The product was dissolved in deionized water, dialyzed using a dialysis bag with a molecular weight cutoff of 3000 Da for 40 h, and freeze-dried to obtain an antibacterial composite modified material.

[0022] The isocyanate-terminated oligolactic acid in step S1 is hexamethylene diisocyanate-terminated oligolactic acid, which has a number average molecular weight of 2000 Da and an isocyanate group content of 1.0 wt %.

[0023] In step S2, the number average molecular weight of the polycaprolactone is 50,000 Da, the thickness of the hydrophobic nanofiber layer is 100 μm, and the thickness of the hydrophilic nanofiber layer is 50 μm.

[0024] In step S1, the spinning voltage is 12 kV, the receiving distance is 10 cm, the flow rate is 0.3 mL / h, and the ambient humidity is ≤40%.

[0025] In step S2, the spinning voltage is 15 kV, the receiving distance is 15 cm, the flow rate is 0.8 mL / h, and the ambient humidity is ≤40%.

[0026] Example 2: A functional nanofiber dressing for burn and scald wound healing is prepared by the following steps: S1, mixing an antibacterial composite modified material and an isocyanate-terminated oligolactic acid in a mass ratio of 1:3, dissolving the mixture in a mixed solvent of chloroform and N,N-dimethylacetamide in a volume ratio of 5:1 to form a first spinning solution with a total solid content of 20 wt%, and electrospinning the first spinning solution to obtain a hydrophilic nanofiber layer; S2. Dissolve polycaprolactone in a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 5:1 to form a second spinning solution with a mass concentration of 15 wt%. Electrospin the second spinning solution on the surface of the hydrophilic nanofiber layer to form a hydrophobic nanofiber layer covering the hydrophilic nanofiber layer to form a double-layer structure. The resulting mixture is heat-treated at 70°C for 24 hours to obtain a nanofiber functional dressing.

[0027] The antibacterial composite modified material is prepared by the following steps: (1) Under nitrogen protection, 12 g (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid was dissolved in 150 mL of anhydrous dichloromethane, cooled to 5 °C, and a mixed solution consisting of 80 mL of thionyl chloride and 0.5 mL of N,N-dimethylformamide was slowly added dropwise. After the addition was complete, the temperature was raised to 30 °C and the reaction was carried out for 6 h. The solvent and excess thionyl chloride were removed by distillation under reduced pressure to obtain intermediate A. (2) Dissolve 15 g of intermediate A in 220 mL of dichloromethane, cool to 5 °C, and dropwise add a solution containing 7.5 g of N,N-bis(2-benzimidazolemethyl)amine, 15 mL of triethylamine, and 20 mL of anhydrous tetrahydrofuran. After the addition is complete, heat to 70 °C and reflux for 15 h. Cool to room temperature, add water to precipitate the solid, filter, and wash with cold water to obtain intermediate B. (3) 10 g of intermediate B and 6 g of potassium carbonate were added to 150 mL of N,N-dimethylformamide, stirred at 80 °C for 2 h, 6 g of benzyl chloride was slowly added, and the reaction was continued for 30 h. The mixture was cooled to room temperature, filtered to remove the solid, and the filtrate was poured into 5 times the volume of ethanol for precipitation. The precipitate was collected and washed with ethanol 3 times. The product was dissolved in deionized water, dialyzed using a dialysis bag with a molecular weight cutoff of 5000 Da for 50 h, and freeze-dried to obtain an antibacterial composite modified material.

[0028] The isocyanate-terminated oligolactic acid in step S1 is hexamethylene diisocyanate-terminated oligolactic acid with a number average molecular weight of 5000 Da and an isocyanate group content of 3.0 wt %.

[0029] In step S2, the number average molecular weight of the polycaprolactone is 100,000 Da, the thickness of the hydrophobic nanofiber layer is 300 μm, and the thickness of the hydrophilic nanofiber layer is 150 μm.

[0030] In step S1, the spinning voltage is 18 kV, the receiving distance is 20 cm, the flow rate is 1.0 mL / h, and the ambient humidity is ≤40%.

[0031] In step S2, the spinning voltage is 20 kV, the receiving distance is 25 cm, the flow rate is 1.5 mL / h, and the ambient humidity is ≤40%.

[0032] Example 3: A functional nanofiber dressing for burn and scald wound healing is prepared by the following steps: S1, mixing an antibacterial composite modified material and an isocyanate-terminated oligolactic acid in a mass ratio of 1:2, dissolving the mixture in a mixed solvent of chloroform and N,N-dimethylacetamide in a volume ratio of 4:1 to form a first spinning solution with a total solid content of 15 wt%, and electrospinning the first spinning solution to obtain a hydrophilic nanofiber layer; S2. Dissolve polycaprolactone in a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 4:1 to form a second spinning solution with a mass concentration of 12 wt%. Electrospin the second spinning solution on the surface of the hydrophilic nanofiber layer to form a hydrophobic nanofiber layer covering the hydrophilic nanofiber layer to form a double-layer structure. The resulting mixture is heat-treated at 60°C for 16 hours to obtain a nanofiber functional dressing.

[0033] The antibacterial composite modified material is prepared by the following steps: (1) Under nitrogen protection, 10 g of (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid was dissolved in 135 mL of anhydrous dichloromethane, cooled to 3 °C, and a mixed solution consisting of 65 mL of thionyl chloride and 0.4 mL of N,N-dimethylformamide was slowly added dropwise. After the addition was complete, the temperature was raised to 25 °C and the reaction was continued for 4.5 h. The solvent and excess thionyl chloride were removed by distillation under reduced pressure to obtain intermediate A. (2) Dissolve 11.5 g of intermediate A in 210 mL of dichloromethane, cool to 3 °C, and dropwise add a solution containing 6.35 g of N,N-bis(2-benzimidazolemethyl)amine, 12.5 mL of triethylamine, and 15 mL of anhydrous tetrahydrofuran. After the addition is complete, heat to 60 °C and reflux for 12.5 h. Cool to room temperature, add water to precipitate the solid, filter, and wash with cold water to obtain intermediate B. (3) 8.5 g of intermediate B and 5.1 g of potassium carbonate were added to 135 mL of N,N-dimethylformamide, stirred at 65 °C for 1.25 h, 5.1 g of benzyl chloride was slowly added, and the reaction was continued for 25 h. The mixture was cooled to room temperature, filtered to remove the solid, and the filtrate was poured into 4 times the volume of ethanol for precipitation. The precipitate was collected and washed with ethanol 3 times. The product was dissolved in deionized water, dialyzed using a dialysis bag with a molecular weight cutoff of 4000 Da for 45 h, and freeze-dried to obtain an antibacterial composite modified material.

[0034] The isocyanate-terminated oligolactic acid in step S1 is hexamethylene diisocyanate-terminated oligolactic acid with a number average molecular weight of 3500 Da and an isocyanate group content of 2.0 wt %.

[0035] In step S2, the number average molecular weight of the polycaprolactone is 75,000 Da, the thickness of the hydrophobic nanofiber layer is 200 μm, and the thickness of the hydrophilic nanofiber layer is 100 μm.

[0036] In step S1, the spinning voltage is 15 kV, the receiving distance is 15 cm, the flow rate is 0.65 mL / h, and the ambient humidity is ≤40%.

[0037] In step S2, the spinning voltage is 18 kV, the receiving distance is 20 cm, the flow rate is 1.15 mL / h, and the ambient humidity is ≤40%.

[0038] Comparative Example 1: The hydrophilic nanofiber layer in this comparative example is replaced with a polyethylene glycol-polylactic acid copolymer, the mass ratio of polyethylene glycol and polylactic acid is 70:30, and the copolymer is dissolved in a mixed solvent of chloroform and N,N-dimethylacetamide in a volume ratio of 4:1 to form a first spinning solution with a total solid content of 15 wt%. The first spinning solution is electrospun to obtain a hydrophilic nanofiber layer. The rest is the same as Example 3.

[0039] Test Example 1: Functional Dressing Tensile Strength Test The dressing samples prepared in Examples 1-3 and Comparative Example 1 were cut into 50 mm × 10 mm rectangular strips and subjected to tensile strength tests using a WDW-3020 electronic universal material testing machine. The clamp spacing was 30 mm, the tensile speed was 100 mm / min, and each group was tested 5 times. The test results are shown in Table 1. Figure 1 .

[0040] Depend on Figure 1 It can be seen that the functional dressing prepared by the present invention exhibits higher tensile strength. Compared with comparative example 1, the tear strength is improved after modification. Therefore, the functional dressing can meet the use requirements of active parts such as joints.

[0041] Test Example 2: Cytotoxicity Test of Functional Dressing (1) Preparation of material extract: After cutting each dressing sample prepared in Examples 1-3 and Comparative Example 1 into small pieces, add them into DMEM culture medium at a ratio of 0.1 g / mL, extract them in a 37°C, 5% CO2 incubator for 24 h, and filter them through a 0.22 μm filter membrane for sterilization to obtain a material extract.

[0042] (2) Cell inoculation: Mouse epithelial cells in the logarithmic growth phase were digested with 0.25% trypsin and the cell concentration was adjusted to 5×10 4 The cells were plated at 100 μL / mL in a 96-well plate and cultured in a 37°C, 5% CO2 incubator for 24 h.

[0043] (3) Drug treatment: The original culture medium in the wells was discarded, and the material extracts of different concentrations (100%, 50%, and 25%) of Examples 1-3 and Comparative Example 1 were added, 100 μL per well, and 5 replicate wells were set for each group. The culture was continued for 24 h and 48 h. (4) Detection: Add 10 μL of CCK-8 solution to each well, continue incubation for 4 h, and then use a microplate reader to measure the absorbance (OD value) of each well at a wavelength of 450 nm.

[0044] (5) Calculate the cell survival rate: Cell survival rate (%) = (OD value of the experimental group - OD value of the blank group) / (OD value of the negative control group - OD value of the blank group) × 100%.

[0045] The above test results can be found in Figure 2 .

[0046] Depend on Figure 2 It can be seen that the functional dressing prepared by the present invention exhibits low toxicity at different concentrations, which is equivalent to the cytotoxicity of Comparative Example 1, indicating that the hydrophilic fiber layer of the functional dressing prepared by the preparation method of the present invention exhibits biocompatibility similar to that of the hydrophilic nanofiber layer prepared by polyethylene glycol-polylactic acid copolymer.

[0047] Test Example 3: Antibacterial Test of Functional Dressing (1) Preparation of bacterial liquid: Staphylococcus aureus and Escherichia coli were inoculated into nutrient agar medium and cultured at 37℃ for 24h; Candida albicans were inoculated into Sabouraud glucose agar medium and cultured at 28℃ for 48h. Single colonies were picked and inoculated into the corresponding liquid culture medium, and cultured in a shaking incubator at 37℃ (28℃ for Candida albicans) until the logarithmic growth phase. The bacterial liquid concentration was adjusted to 10 with physiological saline. 6 CFU / mL. (2) Determination of antibacterial rate: Mix 100 μL of bacterial solution with 100 μL of dressing extract (prepared as in Test Example 2). Incubate at 37°C (28°C for Candida albicans) for 2 h. Then, spread 100 μL of the mixture on the corresponding agar plate and count the colonies after incubation. Antibacterial rate (%) = (number of colonies in the control group - number of colonies in the experimental group) / number of colonies in the control group × 100%.

[0048] The above test results can be found in Figure 3 .

[0049] from Figure 3 It can be seen that the functional dressing prepared by the present invention exhibits highly effective antibacterial properties against Staphylococcus aureus, Escherichia coli, and Candida albicans, and thus can effectively prevent wound infection.

[0050] Test Example 4: Experiment on the healing of burn wounds with functional dressings in rats (1) Establishment of SD rat burn model: After 1 week of adaptive feeding, SD rats (6 weeks old, weighing 160-200 g) were anesthetized with 10% chloral hydrate (3 mL / kg) intraperitoneally. The backs were depilated. A 15 mm diameter copper rod was heated in an 80 °C constant temperature water bath for 5 min and then pressed vertically on the depilated area on the back of the rats for 3 s, causing deep second-degree burn wounds. (2) Functional dressing repair: 30 rats were randomly divided into 3 groups, 10 rats in each group, namely the blank group (the wound was covered with saline gauze), the control group (covered with the dressing of Comparative Example 1), and the experimental group (covered with the dressing of Example 3). After surgery, the skin around the wound was disinfected with iodine tincture every day, the dressing was changed, and the wound healing was observed. (3) Observation of healing status: The wound healing status of rats was observed on the 7th and 14th days after surgery. The results are shown in Figure 4 .

[0051] Depend on Figure 4 It can be seen that compared with the blank group, the healing speed of the burn wounds of the rats in the control group and the experimental group was significantly accelerated, and the healing speed of the rats in the experimental group was better than that of the control group. The wounds were basically healed on the 14th day after surgery, and the repair effect was the best. This shows that the nanofiber functional dressing has a good ability to promote repair, can promote the healing of burn wounds, and reduce symptoms such as infection and inflammation.

[0052] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0053] The present invention and its embodiments are described above. Such description is not restrictive. The drawings show only one embodiment of the present invention, and actual applications are not limited thereto. In short, if a person skilled in the art is inspired by the above, and does not deviate from the purpose of the present invention, any method and embodiment similar to the technical solution without creative design shall fall within the scope of protection of the present invention.

Claims

1. A functional nanofiber dressing for burn and scald wound healing, characterized by: Prepared by the following steps: S1, mixing an antibacterial composite modified material and an isocyanate-terminated oligolactic acid in a mass ratio of 1:1-3, dissolving the mixture in a mixed solvent of chloroform and N,N-dimethylacetamide in a volume ratio of 3-5:1 to form a first spinning solution with a total solid content of 10-20 wt%, and electrospinning the first spinning solution to obtain a hydrophilic nanofiber layer; S2. Dissolve polycaprolactone in a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3-5:1 to form a second spinning solution with a mass concentration of 8-15wt%. Electrospin the second spinning solution on the surface of the hydrophilic nanofiber layer to form a hydrophobic nanofiber layer covering the hydrophilic nanofiber layer to form a double-layer structure. Then, heat treat the mixture at 50-70°C for 8-24h to obtain a nanofiber functional dressing.

2. The nanofiber functional dressing for burn and scald wound healing according to claim 1, characterized in that: The antibacterial composite modified material is prepared by the following steps: (1) Under nitrogen protection, (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid was dissolved in anhydrous dichloromethane, then cooled to 0-5°C, and a mixed solution of thionyl chloride and N,N-dimethylformamide was slowly added dropwise. After the addition was complete, the temperature was raised to 20-30°C and the reaction was continued for 3-6 hours. The solvent and excess thionyl chloride were removed by distillation under reduced pressure to obtain intermediate A. (2) Dissolve intermediate A in dichloromethane, cool to 0-5°C, and add dropwise an anhydrous tetrahydrofuran solution containing N,N-bis(2-benzimidazolemethyl)amine and triethylamine. After the addition is complete, heat to 50-70°C and reflux for 10-15 hours. Then cool to room temperature, add water to precipitate the solid, filter, and wash with cold water to obtain intermediate B. (3) Add intermediate B and potassium carbonate to N,N-dimethylformamide, stir at 50-80°C for 0.5-2h, slowly add benzyl chloride, continue the reaction for 20-30h, cool to room temperature, filter to remove solids, pour the filtrate into 3-5 times the volume of ethanol for precipitation, collect the precipitate and wash it with ethanol three times, dissolve the product in deionized water, dialyze using a dialysis bag with a molecular weight cutoff of 3000-5000Da for 40-50h, and freeze-dry to obtain an antibacterial composite modified material.

3. The nanofiber functional dressing for burn and scald wound healing according to claim 2, characterized in that: In the step (1), the feeding ratio of (9CI)-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-dipropionic acid, dichloromethane, thionyl chloride, and N,N-dimethylformamide is 8-12 g: 120-150 mL: 50-80 mL: 0.3-0.5 mL.

4. The nanofiber functional dressing for burn and scald wound healing according to claim 2, characterized in that: In the step (2), the feed ratio of intermediate A, dichloromethane, N,N-bis(2-benzimidazolemethyl)amine, triethylamine, and anhydrous tetrahydrofuran is 8-15 g: 200-220 mL: 5.2-7.5 g: 10-15 mL: 10-20 mL.

5. The nanofiber functional dressing for burn and scald wound healing according to claim 2, characterized in that: In step (3), the feed ratio of intermediate B, potassium carbonate, N,N-dimethylformamide, and benzyl chloride is 7-10 g: 120-150 mL: 4.2-6 g.

6. The nanofiber functional dressing for burn and scald wound healing according to claim 1, characterized in that: In step S1, the isocyanate-terminated oligolactic acid is hexamethylene diisocyanate-terminated oligolactic acid, has a number average molecular weight of 2000-5000 Da, and an isocyanate group content of 1.0-3.0 wt%.

7. The nanofiber functional dressing for burn and scald wound healing according to claim 1, characterized in that: The number average molecular weight of the polycaprolactone in step S2 is 50,000-100,000 Da, the thickness of the hydrophobic nanofiber layer is 100-300 μm, and the thickness of the hydrophilic nanofiber layer is 50-150 μm.

8. The nanofiber functional dressing for burn and scald wound healing according to claim 1, characterized in that: In step S1, the spinning voltage is 12-18 kV, the receiving distance is 10-20 cm, the flow rate is 0.3-1.0 mL / h, and the ambient humidity is ≤40%.

9. The nanofiber functional dressing for burn and scald wound healing according to claim 1, characterized in that: In step S2, the spinning voltage is 15-20 kV, the receiving distance is 15-25 cm, the flow rate is 0.8-1.5 mL / h, and the ambient humidity is ≤40%.

Images