A method of preparing a nanofiber membrane dressing

Abstract

This invention discloses a method for preparing a nanofiber membrane dressing, comprising the following steps: S1, preparing hydrophobic and hydrophilic polymers into solutions A and B of different concentrations, respectively; preparing a drug and a hydrophilic encapsulating material into solutions C and D of different concentrations; S2, using electrospinning to spray solution A onto a silicone oil substrate to obtain a hydrophobic layer; S3, after the hydrophobic layer reaches a certain thickness, using coaxial electrospraying to spray solutions C and D onto the hydrophobic layer to obtain a drug layer; S4, after the drug layer reaches a certain thickness, spraying with solution B to obtain a hydrophilic layer; S5, after the hydrophilic layer reaches a certain thickness, spraying again with solution A to obtain a second hydrophobic layer; S6, after the second hydrophobic layer reaches a certain thickness, spraying with solution B to obtain a second hydrophilic layer; S7, after the second hydrophilic layer reaches a certain thickness, covering it with a protective material. This dressing possesses waterproof and breathable properties as well as drug sustained-release functionality.

Description

Technical Field

[0001] This invention relates to the field of biomedical device materials technology, and in particular to a method for preparing a nanofiber dressing. Background Technology

[0002] The skin is the largest organ in the human body, with functions including blocking the invasion of external pathogens and preventing the loss of bodily fluids. Due to mechanical trauma, burns, and pathological ulcers, local skin damage leads to the loss of its original functions. Therefore, an ideal wound dressing should be waterproof, breathable, and capable of holding medications.

[0003] Currently, the mainstream preparation method is chemical cross-linking, which has many drawbacks: First, many traditional chemical cross-linking agents have certain cytotoxicity, and incomplete removal after the reaction may cause inflammatory reactions; second, the chemical cross-linking process often requires precise control of reaction conditions (such as pH and temperature) or the use of additional energy input (such as ultraviolet irradiation), which increases the complexity of the process and production costs; third, the structure of the prepared dressing is uncontrollable, usually forming only a dense, single three-dimensional network structure, which cannot achieve controlled drug release and large amount of exudate management.

[0004] From a fabrication process perspective, electrospinning / electrospinning technology can directly construct porous nanofiber networks with large specific surface areas. This structure is very similar to the extracellular matrix, which facilitates gas exchange, cell adhesion, proliferation, and controlled migration, which is crucial for drug loading and release. Furthermore, the large number of nanofibers facilitates the construction of asymmetric hydrophilic-hydrophobic interfaces, thereby achieving unidirectional moisture permeability. Electrospinning / electrospinning technology provides a new approach for the preparation of wound dressings.

[0005] However, how to combine waterproof and breathable properties with sustained drug release to achieve integrated fiber membrane functions remains a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to address the shortcomings of existing technologies by providing a functionally coupled nanofiber wound dressing. This dressing utilizes a combination of electrospinning and electrospraying processes to design a nanofiber wound dressing with both drug sustained-release and waterproof / breathable functions. The multi-layered nanofiber structure formed by electrospinning creates various nanofiber membranes with different functions. By integrating these membranes based on their different properties, an asymmetric hydrophilic / hydrophobic gradient and drug loading and controlled release are achieved, thus enabling the dressing to possess both waterproof / breathable and drug sustained-release functions.

[0007] The specific technical solution adopted in this invention is as follows: A method for preparing a nanofiber membrane dressing includes the following steps: S1. Prepare solutions A and B of different concentrations using hydrophobic and hydrophilic polymers, respectively; prepare solutions C and D of different concentrations using metformin hydrochloride and polyacrylic acid as a hydrophilic encapsulating material, respectively. The hydrophobic polymers include ethyl cellulose and chitosan bio-based materials; the hydrophilic polymers are polyvinyl alcohol. S2. Solution A is sprayed onto the silicone oil substrate using an electrospinning process to obtain a hydrophobic layer; S3. After the hydrophobic layer reaches a certain thickness, coaxial electrospray technology is used to spray solution C and solution D onto the hydrophobic layer to obtain the drug layer. S4. After the drug layer reaches a certain thickness, replace solution B for printing to obtain a hydrophilic layer. S5. After the hydrophilic layer reaches a certain thickness, replace solution A and print again to obtain the second hydrophobic layer. S6. After the second hydrophobic layer reaches a certain thickness, replace solution B for printing to obtain the second hydrophilic layer. S7. After the second hydrophilic layer reaches a certain thickness, cover it with a medical polyurethane film as a protective material.

[0008] This invention employs multilayer electrospinning and printing. Through electrospinning and coaxial electrospraying, the material ratio, structure, and function of the composite process can be controlled online. The materials produced by electrospinning and coaxial electrospraying change from a solution state to a solid state, allowing functional materials to be incorporated into the fiber membrane and endowing it with functionality.

[0009] Furthermore, in solution A, ethyl cellulose accounts for 10-17.5 wt% of the total mass of solution A, and chitosan accounts for 1-2 wt% of the total mass of solution A. In solution B, polyvinyl alcohol accounts for 6-10 wt% of the total mass of solution B; In solution C, metformin hydrochloride accounts for 4-6 wt% of the total mass of solution C; In the solution D, polyacrylic acid accounts for 4 to 6 wt% of the total mass of the solution D.

[0010] Furthermore, the solutions C and D used for coaxial electrospraying are set up with coaxial nozzles, with solution D as the outer layer and connected by a hose, and solution C as the inner layer.

[0011] Furthermore, an external electric field is applied between the electrospinning nozzle and / or the coaxial electrospray nozzle and the receiving surface; the electrostatic voltage of the electrospinning process is 15~20 kV; the electrostatic voltage of the electrospray process is 20~24 kV; and the distance between the electrospinning nozzle and the electrospray nozzle and the receiving surface is 12~17 cm.

[0012] Preferably, the receiving surface is the surface of the receiving device; the receiving device is a roller receiving device or a flat receiving device; the moving speed of the receiving surface is 20~25 m / min.

[0013] The electrospinning process parameters are as follows: liquid supply rate is 0.4~1.0 mL / h, electrostatic voltage is 15~20 kV, and electrospinning distance is 12~18 cm.

[0014] Furthermore, the electrospun thickness of the hydrophobic layer is 70~100 μm.

[0015] Furthermore, the electrospun thickness of the hydrophilic layer is 100~150 μm.

[0016] Furthermore, the electrospun thickness of the drug layer is 30~50 μm.

[0017] The beneficial effects of this invention are: 1. The drug layer and hydrophobic layer of the present invention are combined with the hydrophilic layer in the form of droplets and fibers. This combination not only has the advantages of large specific surface area and fiber interweaving of nanofibers, but also improves the weak interfacial bonding of the hydrophilic-hydrophobic asymmetric structure by combining coaxial drug droplets with nanofiber membranes with hydrophilic-hydrophobic gradient. This not only enables the dressing to have drug loading and sustained drug release, but also improves the disadvantage of weak interfacial bonding of hydrophilic-hydrophobic gradient caused by the addition of the drug layer.

[0018] 2. This invention employs electrospinning and coaxial electrospraying for layer-by-layer printing, which allows for control of the structure and printing time, enabling precise coupling of multilayer functional fiber membranes.

[0019] 3. The drug layer is encapsulated by a pH-responsive polyacrylic acid material, which enables controlled release of the drug inside.

[0020] 4. The construction of multi-layer hydrophilic and hydrophobic gradients enables multi-level exudate management of dressings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the dressing structure. Figure 2 Process flow diagram for dressing preparation Figure 3 This is a scanning electron microscope image of the hydrophobic layer; Figure 4 This is a scanning electron microscope image of the hydrophilic layer; Figure 5 Scanning electron microscope image of coaxial droplets in the drug layer; Figure 6 Diagram showing the water contact angle on the hydrophobic side of the dressing; Figure 7 Diagram showing the water contact angle of the hydrophilic side of the dressing; Figure 8 An image showing droplet transport on the hydrophobic side of the dressing; Figure 9 This image shows droplet transport on the hydrophilic side of the dressing. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. At the same time, the raw materials mentioned below, unless otherwise specified, are all commercially available products; the process steps or preparation methods not mentioned in detail are all process steps or preparation methods known to those skilled in the art.

[0023] The test methods for the following examples and comparative examples are as follows: 1. The wettability of the fiber membrane was measured using a contact angle analyzer at 25°C with a 3μL water droplet.

[0024] 2. Unidirectional liquid transport behavior test: The test was conducted using bromomethyl vanillin blue solution, with a size of 5×1cm. 2 The fiber dressing was fixed with a clamping device, bromomethyl fennel blue solution was dripped onto both sides of the dressing, and the transportation process of the water droplets was recorded by a camera. Example 1

[0025] (a) Preparation of hydrophilic / hydrophobic layer solutions and drug droplet solutions: S1. Weigh 1.5 g of ethyl cellulose (EC, molecular weight 130,000) powder and 0.15 g of chitosan (CS, CAS No.: 9012-76-4), dissolve them in 6.68 g of ethanol and 1.67 g of deionized water, and stir thoroughly until completely dissolved to form a homogeneous solution A; weigh 0.8 g of polyvinyl alcohol (PVA, CAS No.: 9002-89-5) powder, dissolve it in 1.84 g of ethanol and 7.36 g of deionized water, heat at 90°C and stir thoroughly until completely dissolved to form a homogeneous solution B; S2. Weigh 0.5 g of metformin hydrochloride (CAS No.: 1115-70-4) powder and dissolve it in 4.75 g of ethanol and 4.75 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution C. Weigh 0.5 g of polyacrylic acid (PAA, molecular weight 450,000) powder and dissolve it in 1.9 g of ethanol and 7.6 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution D. (II) Preparation of dressings by electrospinning / electrospinning: S3. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the silicone oil substrate is 15 cm, resulting in a hydrophobic layer with a thickness of 80 μm. S4. Solution C is used as the inner layer of coaxial electrospinning, and solution D is used as the outer layer of coaxial electrospinning. The solution is sprayed out through the coaxial electrospinning nozzle. The flow rate of solution C is 0.8 mL / h, the flow rate of solution D is 1.0 mL / h, the electrostatic voltage is 20 kV, and the distance between the electrospinning nozzle and the hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a drug layer with a thickness of 40 μm. S5. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the drug layer is 15 cm, resulting in a hydrophilic layer with a thickness of 120 μm. S6. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the hydrophilic layer formed by electrospinning solution B is 15 cm, resulting in a second hydrophobic layer with a thickness of 80 μm. S7. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the second hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a second hydrophilic layer with a thickness of 120 μm. S8. Cover the formed second hydrophilic layer with a protective medical polyurethane film; The prepared dressing was subjected to a water contact angle test, and its unidirectional liquid transfer performance was also tested. Example 2

[0026] (a) Preparation of hydrophilic / hydrophobic layer solutions and drug droplet solutions: S1. Weigh 1.0 g of ethyl cellulose (EC, molecular weight 130,000) powder and 0.10 g of chitosan (CS, CAS No.: 9012-76-4), dissolve them in 7.12 g of ethanol and 1.78 g of deionized water, and stir thoroughly until completely dissolved to form a homogeneous solution A; weigh 0.6 g of polyvinyl alcohol (PVA, CAS No.: 9002-89-5) powder, dissolve it in 1.88 g of ethanol and 7.52 g of deionized water, heat at 90°C and stir thoroughly until completely dissolved to form a homogeneous solution B; S2. Weigh 0.4 g of metformin hydrochloride (CAS No.: 1115-70-4) powder and dissolve it in 4.8 g of ethanol and 4.8 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution C. Weigh 0.4 g of polyacrylic acid (PAA, molecular weight 450,000) powder and dissolve it in 1.92 g of ethanol and 7.68 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution D. (II) Preparation of dressings by electrospinning / electrospinning: S3. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the silicone oil substrate is 15 cm, resulting in a hydrophobic layer with a thickness of 70 μm. S4. Solution C is used as the inner layer of coaxial electrospinning, and solution D is used as the outer layer of coaxial electrospinning. The solution is sprayed out through the coaxial electrospinning nozzle. The flow rate of solution C is 0.8 mL / h, the flow rate of solution D is 1.0 mL / h, the electrostatic voltage is 20 kV, and the distance between the electrospinning nozzle and the hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a drug layer with a thickness of 30 μm. S5. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the drug layer is 15 cm, resulting in a hydrophilic layer with a thickness of 100 μm. S6. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the hydrophilic layer formed by electrospinning solution B is 15 cm, resulting in a second hydrophobic layer with a thickness of 80 μm. S7. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the second hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a second hydrophilic layer with a thickness of 120 μm. S8. Cover the formed second hydrophilic layer with a protective medical polyurethane film; The prepared dressing was subjected to a water contact angle test, and its unidirectional liquid transfer performance was also tested. Example 3

[0027] (a) Preparation of hydrophilic / hydrophobic layer solutions and drug droplet solutions: S1. Weigh 1.75 g of ethyl cellulose (EC, molecular weight 130,000) powder and 0.2 g of chitosan (CS, CAS No.: 9012-76-4), dissolve them in 6.44 g of ethanol and 1.61 g of deionized water, and stir thoroughly until completely dissolved to form a homogeneous solution A; weigh 1.0 g of polyvinyl alcohol (PVA, CAS No.: 9002-89-5) powder, dissolve it in 1.8 g of ethanol and 7.2 g of deionized water, heat at 90°C and stir thoroughly until completely dissolved to form a homogeneous solution B; S2. Weigh 0.6 g of metformin hydrochloride (CAS No.: 1115-70-4) powder and dissolve it in 4.7 g of ethanol and 4.7 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution C. Weigh 0.6 g of polyacrylic acid (PAA, molecular weight 450,000) powder and dissolve it in 1.88 g of ethanol and 7.52 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution D. (II) Preparation of dressings by electrospinning / electrospinning: S3. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the silicone oil substrate is 15 cm, resulting in a hydrophobic layer with a thickness of 95 μm. S4. Solution C is used as the inner layer of coaxial electrospinning, and solution D is used as the outer layer of coaxial electrospinning. The solution is sprayed out through the coaxial electrospinning nozzle. The flow rate of solution C is 0.8 mL / h, the flow rate of solution D is 1.0 mL / h, the electrostatic voltage is 20 kV, and the distance between the electrospinning nozzle and the hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a drug layer with a thickness of 50 μm. S5. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the drug layer is 15 cm, resulting in a hydrophilic layer with a thickness of 140 μm. S6. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the hydrophilic layer formed by electrospinning solution B is 15 cm, resulting in a second hydrophobic layer with a thickness of 80 μm. S7. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the second hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a second hydrophilic layer with a thickness of 120 μm. S8. Cover the formed second hydrophilic layer with a protective medical polyurethane film; The prepared dressing was subjected to a water contact angle test, and its unidirectional liquid transfer performance was also tested.

[0028] Comparative Example 1 (a) Preparation of hydrophilic / hydrophobic aqueous film solution and drug droplet solution: S1. Weigh 1.5 g of ethyl cellulose (EC, molecular weight 130,000) powder and 0.15 g of chitosan (CS, CAS No.: 9012-76-4), dissolve them in 6.68 g of ethanol and 1.67 g of deionized water, and stir thoroughly until completely dissolved to form a homogeneous solution A; weigh 0.8 g of polyvinyl alcohol (PVA, CAS No.: 9002-89-5) powder, dissolve it in 1.84 g of ethanol and 7.36 g of deionized water, heat at 90°C and stir thoroughly until completely dissolved to form a homogeneous solution B; S2. Weigh 0.5 g of metformin hydrochloride (CAS No.: 1115-70-4) powder and dissolve it in 4.75 g of ethanol and 4.75 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution C. Weigh 0.5 g of polyacrylic acid (PAA, molecular weight 450,000) powder and dissolve it in 1.9 g of ethanol and 7.6 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution D. (II) Preparation of dressings by electrospinning / electrospinning: S3. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the silicone oil substrate is 15 cm, resulting in a hydrophobic layer with a thickness of 100 μm. S4. Solution C is used as the inner layer of coaxial electrospinning, and solution D is used as the outer layer of coaxial electrospinning. The solution is sprayed out through the coaxial electrospinning nozzle. The flow rate of solution C is 0.8 mL / h, the flow rate of solution D is 1.0 mL / h, the electrostatic voltage is 20 kV, and the distance between the electrospinning nozzle and the hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a drug layer with a thickness of 30 μm. S5. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the drug layer is 15 cm, resulting in a hydrophilic layer with a thickness of 150 μm. S6. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the hydrophilic layer formed by electrospinning solution B is 15 cm, resulting in a second hydrophobic layer with a thickness of 100 μm. S7. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 15 kV. The distance between the electrospinning nozzle and the second hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a second hydrophilic layer with a thickness of 150 μm. S8. Cover the formed second hydrophilic layer with a protective medical polyurethane film; The prepared dressing was subjected to a water contact angle test, and its unidirectional liquid transfer performance was also tested.

[0029] Comparative Example 2 (a) Preparation of hydrophilic / hydrophobic aqueous film solution and drug droplet solution: S1. Weigh 1.5 g of ethyl cellulose (EC, molecular weight 130,000) powder and 0.15 g of chitosan (CS, CAS No.: 9012-76-4), dissolve them in 6.68 g of ethanol and 1.67 g of deionized water, and stir thoroughly until completely dissolved to form a homogeneous solution A; weigh 0.8 g of polyvinyl alcohol (PVA, CAS No.: 9002-89-5) powder, dissolve it in 1.84 g of ethanol and 7.36 g of deionized water, heat at 90°C and stir thoroughly until completely dissolved to form a homogeneous solution B; S2. Weigh 0.5 g of metformin hydrochloride (CAS No.: 1115-70-4) powder and dissolve it in 4.75 g of ethanol and 4.75 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution C. Weigh 0.5 g of polyacrylic acid (PAA, molecular weight 450,000) powder and dissolve it in 1.9 g of ethanol and 7.6 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution D. (II) Preparation of dressings by electrospinning / electrospinning: S3. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 24 kV. The distance between the electrospinning nozzle and the silicone oil substrate is 15 cm, resulting in a hydrophobic layer with a thickness of 70 μm. S4. Solution C is used as the inner layer of coaxial electrospinning, and solution D is used as the outer layer of coaxial electrospinning. The solution is sprayed out through the coaxial electrospinning nozzle. The flow rate of solution C is 0.8 mL / h, the flow rate of solution D is 1.0 mL / h, the electrostatic voltage is 20 kV, and the distance between the electrospinning nozzle and the hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a drug layer with a thickness of 50 μm. S5. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the drug layer is 15 cm, resulting in a hydrophilic layer with a thickness of 100 μm. S6. Solution A is ejected through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 24 kV. The distance between the electrospinning nozzle and the hydrophilic layer formed by electrospinning solution B is 15 cm, resulting in a second hydrophobic layer with a thickness of 70 μm. S7. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 0.4 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the second hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a second hydrophilic layer with a thickness of 100 μm. S8. Cover the formed second hydrophilic layer with a protective medical polyurethane film; The prepared dressing was subjected to a water contact angle test, and its unidirectional liquid transfer performance was also tested.

[0030] Comparative Example 3 (a) Preparation of hydrophilic / hydrophobic aqueous film solution and drug droplet solution: S1. Weigh 1.5 g of ethyl cellulose (EC, molecular weight 130,000) powder and 0.15 g of chitosan (CS, CAS No.: 9012-76-4), dissolve them in 6.68 g of ethanol and 1.67 g of deionized water, and stir thoroughly until completely dissolved to form a homogeneous solution A; weigh 0.8 g of polyvinyl alcohol (PVA, CAS No.: 9002-89-5) powder, dissolve it in 1.84 g of ethanol and 7.36 g of deionized water, heat at 90°C and stir thoroughly until completely dissolved to form a homogeneous solution B; S2. Weigh 0.5 g of metformin hydrochloride (CAS No.: 1115-70-4) powder and dissolve it in 4.75 g of ethanol and 4.75 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution C. Weigh 0.5 g of polyacrylic acid (PAA, molecular weight 450,000) powder and dissolve it in 1.9 g of ethanol and 7.6 g of deionized water. Stir thoroughly until completely dissolved to form a homogeneous solution D. (II) Preparation of dressings by electrospinning / electrospinning: S3. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 24 kV. The distance between the electrospinning nozzle and the silicone oil substrate is 15 cm, resulting in a hydrophobic layer with a thickness of 80 μm. S4. Solution C is used as the inner layer of coaxial electrospinning, and solution D is used as the outer layer of coaxial electrospinning. The solution is sprayed out through the coaxial electrospinning nozzle. The flow rate of solution C is 0.8 mL / h, the flow rate of solution D is 1.0 mL / h, the electrostatic voltage is 20 kV, and the distance between the electrospinning nozzle and the hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a drug layer with a thickness of 40 μm. S5. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the drug layer is 15 cm, resulting in a hydrophilic layer with a thickness of 120 μm. S6. Solution A is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 24 kV. The distance between the electrospinning nozzle and the hydrophilic layer formed by electrospinning solution B is 15 cm, resulting in a second hydrophobic layer with a thickness of 80 μm. S7. Solution B is sprayed out through an electrospinning nozzle at a flow rate of 1.0 mL / h and an electrostatic voltage of 20 kV. The distance between the electrospinning nozzle and the second hydrophobic layer formed by electrospinning solution A is 15 cm, resulting in a second hydrophilic layer with a thickness of 120 μm. S8. Cover the formed second hydrophilic layer with a protective medical polyurethane film; The prepared dressing was subjected to a water contact angle test, and its unidirectional liquid transfer performance was also tested.

[0031] The test results are shown in Table 1. Table 1

[0032] like Figure 3 and Figure 4 As shown, the nanofibers prepared by electrospinning have a continuous stacked structure. Figure 5 As shown, coaxial electrospinning forms a core-shell structure. Example 1 simultaneously employs electrospinning and coaxial electrospinning to prepare multi-stage dressings, enabling... Figure 4 The coaxial drug nanodroplets were filled into Figure 3 and Figure 4 The nanofiber membranes serve as drug layers. Since the drug layers exist in droplet form, they do not affect the interfacial bonding between hydrophilic and hydrophobic layers. Therefore, they do not affect the asymmetric hydrophilic-hydrophobic gradient constructed by the hydrophilic-hydrophobic fiber membranes, and the addition of the drug layers has no impact on the unidirectional moisture permeability of the dressing. Furthermore, the superposition of the second hydrophobic layer and the second hydrophilic layer enables the dressing to perform multi-stage liquid transport.

[0033] As shown in Table 1, modifying the electrospinning parameters slightly decreased the water contact angle of the resulting hydrophobic fiber membrane. This is because the change in electrospinning parameters affected the electrospinned fibers, resulting in defective fibers in the membrane and thus a slight decrease in hydrophobicity. The same effect was observed with the hydrophilic fiber membrane; its water contact angle increased slightly, indicating a decrease in hydrophilicity. Furthermore, the change in electrospinning parameters also affected the dressing's liquid transport capacity.

[0034] In Examples 1, 2, and 3, the time for the hydrophobic side to transport the liquid through the droplet was approximately 30 seconds. This time aligns with the pathological absorption time of wound exudate. The wound dressing's absorption of exudate should not be too rapid, as this would cause the wound to dry out and fail to maintain moisture; nor should it be too slow, as excessive exudate would provide a rich nutrient environment for bacteria, leading to infection. In contrast, the comparative examples showed that the hydrophobic side had an excessively long liquid transport time, and the hydrophilic side also had a relatively longer liquid absorption time. A comprehensive comparison indicates that the electrospinning parameters of Example 1 offer a more comprehensive performance improvement.

[0035] Although the above embodiments have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the above descriptions are merely embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for preparing a nanofiber membrane dressing, characterized in that, Includes the following steps: S1. Prepare solutions A and B of different concentrations using hydrophobic and hydrophilic polymers, respectively; prepare solutions C and D of different concentrations using metformin hydrochloride and polyacrylic acid as a hydrophilic encapsulating material, respectively. The hydrophobic polymers include ethyl cellulose and chitosan bio-based materials; the hydrophilic polymers are polyvinyl alcohol. S2. Solution A is sprayed onto the silicone oil substrate using an electrospinning process to obtain a hydrophobic layer; S3. After the hydrophobic layer reaches a certain thickness, coaxial electrospray technology is used to spray solution C and solution D onto the hydrophobic layer to obtain the drug layer. S4. After the drug layer reaches a certain thickness, replace solution B for printing to obtain a hydrophilic layer. S5. After the hydrophilic layer reaches a certain thickness, replace solution A and print again to obtain the second hydrophobic layer. S6. After the second hydrophobic layer reaches a certain thickness, replace solution B for printing to obtain the second hydrophilic layer. S7. After the second hydrophilic layer reaches a certain thickness, cover it with protective material.

2. The preparation method according to claim 1, characterized in that, In solution A, ethyl cellulose accounts for 10-17.5 wt% of the total mass of solution A, and chitosan accounts for 1-2 wt% of the total mass of solution A. In solution B, polyvinyl alcohol accounts for 6-10 wt% of the total mass of solution B; In solution C, metformin hydrochloride accounts for 4-6 wt% of the total mass of solution C; In the solution D, polyacrylic acid accounts for 4 to 6 wt% of the total mass of the solution D.

3. The preparation method according to claim 1, characterized in that, The solutions C and D used for coaxial electrospraying are set with coaxial nozzles, with solution D on the outer layer and connected by a hose, and solution C on the inner layer.

4. The preparation method according to claim 1, characterized in that, An external electric field is applied between the electrospinning nozzle and / or the coaxial electrospray nozzle and the receiving surface; the electrostatic voltage of the electrospinning process is 15~20 kV; the electrostatic voltage of the electrospray process is 20~24 kV; the distance between the electrospinning nozzle and the electrospray nozzle and the receiving surface is 12~17 cm.

5. The preparation method according to claim 4, characterized in that, The receiving surface is the surface of the receiving device; the receiving device is a roller receiving device or a flat receiving device; the moving speed of the receiving surface is 20~25 m / min.

6. The preparation method according to claim 4, characterized in that, The electrospinning process parameters are as follows: liquid supply rate is 0.4~1.0 mL / h, electrostatic voltage is 15~20 kV, and electrospinning distance is 12~18 cm.

7. The preparation method according to claim 1, characterized in that, The electrospun thickness of the hydrophobic layer is 70~100 μm.

8. The preparation method according to claim 1, characterized in that, The electrospun thickness of the hydrophilic layer is 100~150 μm.

9. The preparation method according to claim 1, characterized in that, The electrospun thickness of the drug layer is 30~50 μm.

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