Preparation and Application of a Novel Separable Double-Layer Nanofiber Functional Dressing

Abstract

The present invention discloses the preparation and application of a novel separable double-layer nanofiber functional dressing. The dressing comprises a double-layer structure: the lower layer is a coaxial astragaloside IV nanofiber dressing prepared by electrospinning technology, with a diameter of 300 - 1000 nm, having functions such as anti-inflammatory, antioxidant, antibacterial, etc.; the upper layer is a sodium polyacrylate nanofiber dressing prepared by electrospinning technology, with a diameter of 200 - 700 nm, which can absorb the excess exudate on the wound surface and can be separated after absorbing the exudate. The double-layer nanofiber dressing prepared by the present invention can simulate the structure of the human extracellular matrix, has good absorption and infiltration ability, reduces the pressure of the dressing on the wound surface after separation, and has the potential to promote wound healing.

Description

Technical Field

[0001] The present invention belongs to the field of biomaterials and medical devices, and specifically relates to the preparation and application of a novel separable double-layer nanofiber functional dressing. Background Art

[0002] As the physiological barrier between the human body and the external environment, the skin can resist the invasion of external microbial pathogens and protect organs from damage. However, the human skin is relatively fragile and is extremely vulnerable to different types of injuries in daily life and work. When the injury is mild, the skin wound will heal through an orderly and complex process. When the injury is severe, during the self-repair process of the skin, symptoms such as pus, blood, and inflammation will infect the wound surface, making it difficult for the wound to heal. In severe cases, amputation may even occur, posing a threat to the patient's life. Currently, local treatment methods are often used clinically to cover the wound surface with medical dressings, such as gauze, bandages, cotton, etc. However, these dressings only play the role of isolating the external environment and cannot effectively prevent the growth of microorganisms at the wound surface and maintain the microenvironment at the wound surface to accelerate wound healing. Therefore, it is very necessary to prepare a novel multifunctional dressing that can both defend against the growth of wound microorganisms and maintain the wound microenvironment.

[0003] In recent years, nanofiber dressings prepared by electrospinning technology have attracted wide attention from researchers. The nanofibers prepared by electrospinning not only have good biocompatibility but also have characteristics similar to the extracellular matrix structure. When this nanofiber dressing acts on the wound surface, it can accelerate wound healing. In addition, by modifying, decorating, or loading drugs on the nanofiber dressing, researchers can prepare multifunctional dressings to adapt to more skin wound repair application scenarios. Therefore, electrospun nanofibers are one of the ideal skin biomaterials.

[0004] Excessive biological fluids around the wound often lead to infection and hinder wound healing. Currently, double-layer electrospun nanofiber dressings have become a hot spot for the development and achievement transformation of new biomaterial products and have been applied in the fields of wound repair, stomatology, tissue defect, etc. Some researchers have used electrospinning technology to prepare a self-pumping double-layer hydrophilic-hydrophobic nanofiber dressing, but its main side in contact with the wound surface is the hydrophobic layer, and the hydrophilic layer is on the side away from the wound surface, and the wound exudate is unidirectionally discharged to accelerate wound healing. However, the outer dressing of this type almost only plays a role in drainage. When treating the wound, it will not only increase the pressure on the wound but also lead to a decrease in its breathability. Therefore, it is necessary to develop a novel dressing that not only has a drainage effect but also can separate its two layers to reduce the pressure on the wound.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a preparation method and application of a novel separable double-layer nanofiber functional dressing, which solves the problems raised in the above background art.

[0007] To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0008] A preparation method of a novel separable double-layer nanofiber functional dressing, comprising the following steps

[0009] Step (1): Dissolve polyvinylpyrrolidone in absolute ethanol to obtain solution A with a mass ratio of 20% - 60%; dissolve polylactic acid in a mixed solvent of chloroform and acetone to obtain solution B with a mass ratio of 4% - 10%; at the same time, add astragaloside IV to solution A and solution B respectively to obtain the shell spinning solution and the core spinning solution.

[0010] Step (2): Fill the shell spinning solution and the core spinning solution in step (1) into syringes respectively, and use the syringes to spray the nanofibers formed by the shell spinning solution and the core spinning solution spirally onto the receiving plate to obtain a coaxial astragaloside IV nanofiber dressing.

[0011] Step (3): Dissolve polyvinylpyrrolidone, polylactic acid and sodium polyacrylate in a mixed solvent of chloroform and acetone to obtain spinning solution I with a mass ratio of 20%.

[0012] Step (4): Fix the coaxial astragaloside IV nanofiber dressing prepared in step (2) on the receiving plate, suck the spinning solution I obtained in step (3) into the syringe and use the syringe to spray the nanofibers formed by the spinning solution I spirally onto the coaxial astragaloside IV nanofiber dressing on the receiving plate to obtain the double-layer nanofiber functional dressing.

[0013] Optionally, the mass concentration of the shell spinning solution in step (1) is 10mg / mL - 30mg / mL, the mass percentage of the shell spinning solution is 30% - 50%, and the mass concentration of astragaloside IV in the shell spinning solution is 10mg / mL - 15mg / mL;

[0014] Optionally, the mass concentration of the core spinning solution in step (1) is 4mg / mL - 8mg / mL, the mass percentage of the core spinning solution is 6% - 8%, and the mass concentration of astragaloside IV in the core spinning solution is 6mg / mL - 8mg / mL.

[0015] Optionally, the mass ratio of sodium polyacrylate, polyvinylpyrrolidone and polylactic acid in step (3) is (1 - 3):(1 - 4):(3 - 6).

[0016] Optionally, in steps (2) and (4) when spraying nanofibers, a hose is used to connect the syringe to the coaxial needle, and the syringe and the coaxial needle are fixed on a flow pump. Then, the distance between the spinneret needle and the receiving plate is adjusted, and the high-voltage power supply and the flow pump are turned on to complete the spraying of nanofibers.

[0017] Optionally, in steps (2) and (4) when spraying nanofibers, the plate voltage is 5 kV to 25 kV, the flow rate of the spinneret solution in the pump housing layer of thruster A is 0.01 mL / h to 5 mL / h, the flow rate of the spinneret solution in the pump core layer of thruster B is 0.01 mL / h to 5 mL / h, the flow rate of the spinneret solution I in the pump of thruster C is 0.01 mL / h to 5 mL / h, and the receiving distance is 5 cm - 25 cm.

[0018] A novel separable double-layer nanofiber functional dressing is prepared by the above preparation method.

[0019] Optionally, the fiber diameter of the coaxial astragaloside nanofiber dressing is 300 - 1000 nm, and the fiber diameter of the sodium polyacrylate nanofiber dressing is 200 - 700 nm.

[0020] Application of a novel separable double-layer nanofiber functional dressing prepared as above in promoting the healing of skin wounds.

[0021] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described below:

[0022] The present invention prepares an absorbent and osmotic double-layer nanofiber dressing that combines the advantages of polyvinylpyrrolidone, polylactic acid, sodium polyacrylate, astragaloside, etc. Among them, astragaloside has pharmacological effects such as anti-inflammatory and antioxidant. Loading it into the shell-core layer respectively enables the drug to achieve the effect of rapid release and sustained release. Then, by compounding the upper absorbent and osmotic membrane prepared from polyvinylpyrrolidone, polylactic acid, and sodium polyacrylate, the function of the overall dressing is improved. The double-layer dressing not only functions to separate after the upper-layer nanofibrils absorb exudate and relieve the wound pressure, but also can play the role of continuously releasing astragaloside drugs to treat the wound, thereby accelerating wound healing.

[0023] The present invention provides a double-layer nanofiber dressing prepared by electrospinning method, which has excellent water absorption performance, and can be separated after absorbing water to relieve the wound pressure, thereby promoting wound healing.

[0024] The double-layer nanofiber functional dressing prepared by the present invention was tested for water absorption performance, and the results showed that the water absorption rate of the double-layer nanofiber functional dressing prepared by the present invention reached 1345.41±42.02%, indicating that when the double-layer nanofiber dressing prepared by the present invention acts on the wound surface, it can effectively absorb the wound exudate and accelerate wound healing.

[0025] The double-layer nanofiber functional dressing prepared by the present invention was tested for water vapor permeability. The results showed that compared with medical gauze, the water vapor transmission rate of the product of the present invention was higher, indicating that the double-layer fiber functional dressing prepared by the present invention has better mass exchange ability, and this property will be beneficial to the repair of the wound surface.

[0026] The double-layer nanofiber functional dressing prepared by the present invention was tested for in vitro pharmacodynamic experiments. The results showed that the wound area of the rats continued to shrink with the extension of the healing time, and the wound healing speed of the product of the present invention was faster than that of the double-layer dressing without astragaloside IV. On the 14th day, the wound healing rate of the rats in the double-layer nanofiber dressing group loaded with astragaloside IV reached 98%. The results indicated that the double-layer nanofiber functional dressing loaded with astragaloside IV of the present invention could effectively promote wound healing.

[0027] The present invention adopts a unique double-layer nanofiber membrane structure, which solves the problem of loading astragaloside IV in the nanofiber dressing. The prepared product is simple, efficient, and can provide an ideal healing environment for wound healing, promoting wound healing.

[0028] The following further describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. Description of the Drawings

[0029] The following drawings in the description are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0030] Figure 1 It is a physical photograph of the double-layer dressing prepared in Example 4 of the present invention.

[0031] Figure 2 It is a SEM picture of the double-layer fiber membrane: a is the lower layer coaxial nanofiber dressing prepared in Comparative Example 1, b is the upper layer nanofiber dressing prepared in Comparative Example 2, and c is the cross-section of the double-layer nanofiber dressing prepared in Example 4.

[0032] Figure 3 It is a transmission electron microscope picture of the nanofiber prepared in Comparative Example 1 of the present invention.

[0033] Figure 4 It is a picture of the water absorption rate results of the double-layer nanofiber dressings prepared in Example 4, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention.

[0034] Figure 5 It is a picture of the water vapor transmission rate results of the double-layer dressing prepared in Example 4 of the present invention.

[0035] Figure 6 It is a picture of the water absorption and separation process of the double-layer dressing prepared in Example 4 of the present invention.

[0036] Figure 7 It is a picture of the wound healing of rats with the double-layer nanofiber dressings of Example 4 and Comparative Example 3 of the present invention;

[0037] Figure 8 It is a chart of the wound healing of rats with the double-layer nanofiber dressings of Example 4 and Comparative Example 3 of the present invention.

[0038] It should be noted that these drawings and textual descriptions are not intended to limit the scope of the concept of the present invention in any way, but to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0039] The embodiments of the present invention disclose a preparation method of a novel separable double-layer nanofiber functional dressing, including the following steps:

[0040] Step (1): Dissolve polyvinylpyrrolidone in absolute ethanol to obtain liquid A with a mass ratio of 20% to 60%; dissolve polylactic acid in a mixed solvent of chloroform and acetone to obtain liquid B with a mass ratio of 4% to 10%; simultaneously add astragaloside Ⅳ to liquid A and liquid B to obtain the shell spinning solution and the core spinning solution;

[0041] Step (2): Load the shell spinning solution and the core spinning solution in step (1) into syringes respectively, and use the syringes to spray the nanofibers formed by the shell spinning solution and the core spinning solution spirally onto the receiving plate to obtain a coaxial astragaloside Ⅳ nanofiber dressing;

[0042] Step (3): Dissolve polyvinylpyrrolidone, polylactic acid and sodium polyacrylate in a mixed solvent of chloroform and acetone to obtain spinning solution Ⅰ with a mass ratio of 20%;

[0043] Step (4): Fix the coaxial astragaloside Ⅳ nanofiber dressing prepared in step (2) on the receiving plate, suck the spinning solution Ⅰ obtained in step (3) into the syringe and use the syringe to spray the nanofibers formed by the spinning solution Ⅰ spirally onto the coaxial astragaloside Ⅳ nanofiber dressing on the receiving plate to obtain the double-layer nanofiber functional dressing.

[0044] In this embodiment, the mass concentration of the shell spinning solution in step (1) is 10 mg / mL to 30 mg / mL, the mass percentage of the shell spinning solution is 30% to 50%, and the mass concentration of astragaloside IV in the shell spinning solution is 10 mg / mL to 15 mg / mL;

[0045] In this embodiment, the mass concentration of the core spinning solution in step (1) is 4 mg / mL to 8 mg / mL, the mass percentage of the core spinning solution is 6% to 8%, and the mass concentration of astragaloside IV in the core spinning solution is 6 mg / mL to 8 mg / mL.

[0046] In this embodiment, the mass ratio of sodium polyacrylate, polyvinylpyrrolidone and polylactic acid in step (3) is (1 - 3):(1 - 4):(3 - 6).

[0047] In this embodiment, in steps (2) and (4), when spraying nanofibers, a hose is needed to connect the syringe with the coaxial needle, and the syringe and the coaxial needle are fixed on the flow pump, and then the distance between the spinneret and the receiving plate is adjusted, and the high-voltage power supply and the flow pump are turned on to complete the spraying of the nanofibers.

[0048] In this embodiment, in steps (2) and (4), when spraying nanofibers, the plate voltage is 5 kV to 25 kV, the flow rate of the shell spinning solution pumped by propeller A is 0.01 mL / h to 5 mL / h, the flow rate of the core spinning solution pumped by propeller B is 0.01 mL / h to 5 mL / h, the flow rate of the spinning solution I pumped by propeller C is 0.01 mL / h to 5 mL / h, and the receiving distance is 5 cm - 25 cm.

[0049] In this embodiment, when using a syringe to spray the nanofibers formed by the spinning solution I in a spiral shape onto the coaxial astragaloside IV nanofiber dressing on the receiving plate, the upper dressing is a sodium polyacrylate nanofiber dressing.

[0050] A novel separable double-layer nanofiber functional dressing is prepared by the above preparation method.

[0051] In this embodiment, the fiber diameter of the coaxial astragaloside IV nanofiber dressing is 300 - 1000 nm, and the fiber diameter of the sodium polyacrylate nanofiber dressing is 200 - 700 nm.

[0052] An application of the novel separable double-layer nanofiber functional dressing prepared as above in promoting skin wound healing.

[0053] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention.

[0054] It should be understood that the terms used in this invention are only for describing specific embodiments and are not intended to limit the invention. Additionally, for the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0055] Without departing from the scope or spirit of the invention, various improvements and changes can be made to the specific embodiments of the description of the invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of the invention are obvious to those skilled in the art. The description of the invention and the examples are merely exemplary.

[0056] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0057] Example 1: A preparation method of a novel separable double-layer nanofiber functional dressing is provided, including the following steps:

[0058] Step (1): Weigh 1.5 g of polyvinylpyrrolidone and add it to 5 mL of absolute ethanol to obtain a polyvinylpyrrolidone solution with a mass ratio of 30%. At the same time, add astragaloside IV, and after magnetic stirring for 5 h, obtain a shell spinning solution with a mass concentration of 10 mg / mL; weigh 0.3 g of polylactic acid and dissolve it in 5 mL of chloroform:acetone (volume ratio 3:1) to obtain a polylactic acid solution with a mass ratio of 6%. At the same time, add astragaloside IV, and magnetic stir for 6 h to obtain a core spinning solution with a mass concentration of 6 mg / mL.

[0059] Step (2): Load the shell spinning solution and the core spinning solution in step (1) into syringes respectively. Use the syringes to spray the nanofibers formed by the shell spinning solution and the core spinning solution spirally onto the receiving plate to obtain a coaxial astragaloside IV nanofiber dressing; the spinning conditions in step (2): voltage 12 kV, the flow rate of the shell spinning solution of pump A of the propeller is 1.2 mL / h, the flow rate of the core spinning solution of pump B of the propeller is 0.4 mL / h, and the receiving distance is 13 cm, thus obtaining the lower layer core-shell nanofibers.

[0060] Step (3): Weigh 0.2 g of polyvinylpyrrolidone, 0.3 g of polylactic acid, and 0.5 g of sodium polyacrylate and dissolve them in 5 mL of chloroform:acetone (volume ratio 3:1), and magnetic stir for 3 h to obtain a spinning solution I with a mass ratio of 20%;

[0061] Step (4): Fix the coaxial astragaloside nanofiber dressing prepared in step (2) on the receiving plate. Aspirate the spinning solution I obtained in step (3) into a syringe and use the syringe to spirally eject the nanofibers formed by the spinning solution I onto the coaxial astragaloside nanofiber dressing on the receiving plate, thus obtaining a double-layer nanofiber functional dressing. The spinning conditions in step (4) are: voltage 7 kV, the flow rate of the spinning solution I by the propeller C is 0.8 mL / h, and the receiving distance is 13 cm.

[0062] Example 2: A method for preparing a novel separable double-layer nanofiber functional dressing is provided, including the following steps:

[0063] Step (1): Weigh 2 g of polyvinylpyrrolidone and add it to 5 mL of absolute ethanol to obtain a polyvinylpyrrolidone solution with a mass ratio of 40%. At the same time, add astragaloside and magnetically stir for 5 h to obtain a shell spinning solution with a mass concentration of 13 mg / mL. Additionally, weigh 0.3 g of polylactic acid and dissolve it in 5 mL of chloroform:acetone (volume ratio 3:1) to obtain a polylactic acid solution with a mass ratio of 6%. At the same time, add astragaloside and magnetically stir for 6 h to obtain a core spinning solution with a mass concentration of 6 mg / mL.

[0064] Step (2): Load the shell spinning solution and the core spinning solution in step (1) into syringes respectively. Use the syringes to spirally eject the nanofibers formed by the shell spinning solution and the core spinning solution onto the receiving plate to obtain a coaxial astragaloside nanofiber dressing. The spinning conditions in step (2) are: voltage 13 kV, the flow rate of the shell spinning solution by the propeller A pump is 1 mL / h, the flow rate of the core spinning solution by the propeller B pump is 0.4 mL / h, and the receiving distance is 14 cm.

[0065] Step (3): Weigh 0.2 g of polyvinylpyrrolidone, 0.3 g of polylactic acid, and 0.5 g of sodium polyacrylate and dissolve them in 5 mL of chloroform:acetone (volume ratio 3:1), and magnetically stir for 3 h to obtain a spinning solution I with a mass ratio of 20%.

[0066] Step (4): Fix the coaxial astragaloside nanofiber dressing prepared in step (2) on the receiving plate. Aspirate the spinning solution I obtained in step (3) into a syringe and use the syringe to spirally eject the nanofibers formed by the spinning solution I onto the coaxial astragaloside nanofiber dressing on the receiving plate, thus obtaining a double-layer nanofiber functional dressing. The spinning conditions in step (4) are: voltage 7 kV, the flow rate of the propeller pump is 0.8 mL / h, and the receiving distance is 13 cm.

[0067] Example 3: A method for preparing a novel separable double-layer nanofiber functional dressing is provided, including the following steps:

[0068] Step (1): Weigh 2.5 g of polyvinylpyrrolidone and add it to 5 mL of absolute ethanol to obtain a polyvinylpyrrolidone solution with a mass ratio of 50%. At the same time, add astragaloside IV, and after magnetic stirring for 5 h, obtain a shell spinning solution with a mass concentration of 15 mg / mL. Additionally, weigh 0.4 g of polylactic acid and dissolve it in 5 mL of chloroform:acetone (volume ratio 3:1) to obtain a polylactic acid solution with a mass ratio of 8%. At the same time, add astragaloside IV, and after magnetic stirring for 6 h, obtain a core spinning solution with a mass concentration of 8 mg / mL.

[0069] Step (2): Fill the shell spinning solution and the core spinning solution in step (1) into syringes respectively. Use the syringes to spray the nanofibers formed by the shell spinning solution and the core spinning solution spirally onto the receiving plate to obtain a coaxial astragaloside IV nanofiber dressing. The spinning conditions in step (2) are: voltage 15 kV, the flow rate of the shell spinning solution of pump A of the propeller is 1 mL / h, the flow rate of the core spinning solution of pump B of the propeller is 0.4 mL / h, and the receiving distance is 14 cm.

[0070] Step (3): Weigh 0.3 g of polyvinylpyrrolidone, 0.3 g of polylactic acid, and 0.4 g of sodium polyacrylate and dissolve them in 5 mL of chloroform:acetone (volume ratio 3:1), and after magnetic stirring for 3 h, obtain spinning solution I with a mass ratio of 20%.

[0071] Step (4): Fix the coaxial astragaloside IV nanofiber dressing prepared in step (2) on the receiving plate. Inhale spinning solution I obtained in step (3) into a syringe and use the syringe to spray the nanofibers formed by spinning solution I spirally onto the coaxial astragaloside IV nanofiber dressing on the receiving plate, thus obtaining a double-layer nanofiber functional dressing. The spinning conditions in step (4) are: voltage 8 kV, the flow rate of spinning solution I of the propeller pump is 0.8 mL / h, and the receiving distance is 14 cm.

[0072] Example 4: A preparation method of a novel separable double-layer nanofiber functional dressing is provided, including the following steps:

[0073] Step (1): Weigh 2 g of polyvinylpyrrolidone and add it to 5 mL of absolute ethanol to obtain a polyvinylpyrrolidone solution with a mass ratio of 40%. At the same time, add astragaloside IV, and after magnetic stirring for 5 h, obtain a shell spinning solution with a mass concentration of 15 mg / mL. Additionally, weigh 0.4 g of polylactic acid and dissolve it in 5 mL of chloroform:acetone (volume ratio 3:1) to obtain a polylactic acid solution with a mass ratio of 8%. At the same time, add astragaloside IV, and after magnetic stirring for 6 h, obtain a core spinning solution with a mass concentration of 8 mg / mL.

[0074] Step (2): Load the shell spinning solution and the core spinning solution in step (1) into syringes respectively. Use the syringes to spirally eject the nanofibers formed by the shell spinning solution and the core spinning solution onto the receiving plate to obtain a coaxial astragaloside nanofiber dressing; the spinning conditions in step (2): the spinning conditions are as follows: voltage 15 kV, the flow rate of the shell layer of pump A of the propeller is 1 mL / h, the flow rate of the core layer of pump B of the propeller is 0.4 mL / h, and the receiving distance is 15 cm.

[0075] Step (3): Weigh 0.3 g of polyvinylpyrrolidone, 0.3 g of polylactic acid, and 0.4 g of sodium polyacrylate and dissolve them in 5 mL of chloroform:acetone (volume ratio 3:1). Magnetically stir for 3 h to obtain spinning solution I with a mass ratio of 20%.

[0076] Step (4): Fix the coaxial astragaloside nanofiber dressing prepared in step (2) on the receiving plate. Inhale spinning solution I obtained in step (3) into a syringe and use the syringe to spirally eject the nanofibers formed by spinning solution I onto the coaxial astragaloside nanofiber dressing on the receiving plate to obtain a double-layer nanofiber functional dressing. The spinning conditions in step (4) are as follows: 8 kV, the flow rate of the propeller pump is 0.8 mL / h, and the receiving distance is 14 cm.

[0077] Comparative Example 1: Refer to Example 4, the only difference is that there is no upper-layer nanofiber dressing.

[0078] Weigh 2 g of polyvinylpyrrolidone and add it to 5 mL of absolute ethanol to obtain a polyvinylpyrrolidone solution with a mass ratio of 40%. At the same time, add astragaloside and magnetically stir for 5 h to obtain a shell spinning solution with a mass concentration of 15 mg / mL; in addition, weigh 0.4 g of polylactic acid and dissolve it in 5 mL of chloroform:acetone (volume ratio 3:1) to obtain a polylactic acid solution with a mass ratio of 8%. At the same time, add astragaloside and magnetically stir for 6 h to obtain a core spinning solution with a mass concentration of 8 mg / mL. Spinning conditions: voltage 15 kV, the flow rate of the shell layer of pump A of the propeller is 1 mL / h, the flow rate of the core layer of pump B of the propeller is 0.4 mL / h, and the receiving distance is 15 cm.

[0079] Comparative Example 2: Refer to Example 4, the only difference is that there is no lower-layer nanofiber membrane.

[0080] Weigh 0.3 g of polyvinylpyrrolidone, 0.3 g of polylactic acid, and 0.4 g of sodium polyacrylate and dissolve them in 5 mL of chloroform:acetone (volume ratio 3:1). Magnetically stir for 3 h to obtain an upper-layer spinning solution with a mass ratio of 20%. Electrospin the upper-layer spinning solution directly onto the prepared lower-layer core-shell nanofiber dressing. The process parameters are set as follows: 8 kV, the flow rate of the propeller pump is 0.8 mL / h, and the receiving distance is 14 cm.

[0081] Comparative Example 3: Referring to Example 4, the only difference is that it does not encapsulate astragaloside drugs.

[0082] Weigh 2 g of polyvinylpyrrolidone and add it to 5 mL of absolute ethanol. After magnetic stirring for 5 h, a polyvinylpyrrolidone shell spinning solution with a mass ratio of 40% is obtained. Additionally, weigh 0.4 g of polylactic acid and dissolve it in 5 mL of chloroform:acetone (volume ratio 3:1). After magnetic stirring for 6 h, a polylactic acid core spinning solution with a mass ratio of 8% is obtained. Spinning conditions: voltage 15 kV, the flow rate of the shell layer of pump A of the pusher is 1 mL / h, the flow rate of the core layer of pump B of the pusher is 0.4 mL / h, and the receiving distance is 15 cm. Thus, the lower-layer core-shell nanofibers are prepared. Additionally, weigh 0.3 g of polyvinylpyrrolidone, 0.3 g of polylactic acid, and 0.4 g of sodium polyacrylate and dissolve them in 5 mL of chloroform:acetone (volume ratio 3:1). After magnetic stirring for 3 h, an upper-layer spinning solution with a mass ratio of 20% is obtained. The upper-layer spinning solution is directly electrospun onto the prepared lower-layer core-shell nanofiber dressing. The process parameters are set as follows: 8 kV, the flow rate of the pusher pump is 0.8 mL / h, and the receiving distance is 14 cm.

[0083] Experimental Example 1: The nanofiber dressings prepared in Example 4 and Comparative Examples 1 and 2 were subjected to SEM detection, and the detection results are as Figure 2 shown, where a is Comparative Example 1, b is Comparative Example 2, and c is the cross-section of Example 4; it can be Figure 2 seen that in Comparative Example 1, the fibers are smooth and continuous without beading, and the average diameter is about 967 ± 246 nm; in Comparative Example 2, polyacrylate can be seen covering the fiber surface, and the average fiber diameter is 679 ± 307 nm.

[0084] Experimental Example 2: A carbon-coated copper mesh was attached to the receiving plate, and nanofibers were prepared according to Comparative Example 1. The core-shell structure was observed under a transmission electron microscope. The detection results are as Figure 3 shown, and it can be seen that the nanofibers have an obvious core-shell structure and a relatively smooth surface.

[0085] Experimental Example 3: The water absorption rates of the double-layer nanofiber dressings prepared in Example 4 and Comparative Examples 1, 2, and 3 were tested. The specific steps are as follows: Weigh a nanofiber dressing with a size of 2 cm × 2 cm and record it as W1. Immerse it in a petri dish containing 10 mL of deionized water, and calculate the water absorption rate of the nanofiber at 15 min and 30 min according to the following formula (1).

[0086] ×100% (1)

[0087] where W1 is the initial weight of the dressing (g), and W2 is the weight of the dressing at each time point after water absorption (g).

[0088] From Figure 4It can be seen that the water absorption rate of the upper-layer nanofiber dressing reached 2079.32±90.21% at 30 min, the water absorption rate of the lower-layer core-shell nanofiber dressing was 593.43±63.55% at 30 min, the water absorption rate of the double-layer blank nanofiber dressing was 1134.88±24.28% at 30 min, and the water absorption rate of the double-layer astragaloside IV nanofiber dressing was 1345.41±42.02% at 30 min. The results showed that the upper-layer nanofiber dressing had strong water absorption performance. When combined with the lower-layer core-shell nanofiber dressing, a double-layer nanofiber dressing with good water absorption could also be obtained. When acting on the wound surface, it could absorb the wound exudate and accelerate wound healing.

[0089] Experimental Example 4: The water vapor transmission rate of the double-layer nanofiber functional dressing prepared in Example 4 was tested, with a medical gauze dressing as a control. The specific steps were as follows: Cut double-layer nanofiber dressings and medical gauze dressings of appropriate sizes, fix them on the mouth of a round beaker with a diameter of 4 cm (containing 5 mL of deionized water) and weigh them, denoted as W1. After culturing them in an incubator at 37 °C for 24 h, take them out and weigh them, denoted as W2. Calculate the water vapor transmission rate of the dressing according to the following formula (2).

[0090] Water vapor transmission rate ×100% (2)

[0091] where, W1 is the initial weight (g), W2 is the weight after 24 h (g), and A is the surface area of the beaker mouth (mm2)

[0092] The test results are as Figure 5 shown. It can be seen from Figure 5 that compared with the medical gauze dressing, the water vapor transmission rate of Example 4 was higher, indicating that the double-layer nanofiber dressing could evaporate the excess water on the wound surface, had good mass exchange ability, and was beneficial to wound repair.

[0093] Experimental Example 5: The water absorption and separation test of the double-layer nanofiber functional dressing prepared in Example 4 was carried out, and the test results are as Figure 6 shown. It can be seen from Figure 6 that when the nanofiber was water-absorbed for 2 min, the double-layer nanofiber dressing could be separated with tweezers.

[0094] Experimental Example 6: The in vitro pharmacodynamic experiment of the double-layer nanofiber dressings prepared in Example 4 and Comparative Example 3 was carried out. The specific steps were as follows: Select SD rats weighing 220 g±20 g. After 3 days of adaptive feeding, anesthetize them and remove the hair on the back of the rats with a hair removal instrument and a blade. Use a sterilized scissors to cut a circular wound with a diameter of about 1 cm on the back of the rats, and fix the wound with a silicone ring. Apply the dressings of Example 4, Comparative Example 3 and medical gauze respectively, and change the dressings every two days. Calculate the wound healing rate of the rats according to the following formula (3).

[0095] Wound healing rate × 100% (3)

[0096] Wherein, A1 is the initial wound area (cm 2 ) and A2 is the wound area at different times (cm 2 )

[0097] The test results are as Figure 7 shown. As can be seen from Figure 7 , the wound healing speed of the rats in Example 4 and Comparative Example 3 is faster than that of the medical gauze dressing group. The wound healing rate of the Example 4 group reached 38% on the 3rd day, the wound healing rate of Comparative Example 3 reached 15%, while the wound healing rate of the medical gauze dressing group only reached 5%; from the 9th day to the 14th day, the wound healing rate of Example 4 increased from 74% to 98%, the wound healing rate of Comparative Example 3 increased from 60% to 88%, while the wound healing rate of the medical gauze dressing group only increased from 34% to 78%. The results show that when acting on the wound, Example 4 and Comparative Example 3 have better healing effects compared with the medical gauze dressing, and the effect of Example 4 in promoting wound healing is better than that of Comparative Example 3.

[0098] The present invention is not limited to the above embodiments. Anyone should know that structural changes made under the inspiration of the present invention, as long as they have the same or similar technical solutions as the present invention, fall within the protection scope of the present invention. The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A method for preparing a novel detachable double-layer nanofiber functional dressing, characterized in that: The following steps are involved: Step (1): dissolving polyvinyl pyrrolidone in anhydrous ethanol to obtain a liquid A with a mass ratio of 20% to 60%; dissolving polylactic acid in a mixed solvent of chloroform and acetone to obtain a liquid B with a mass ratio of 4% to 10%; and simultaneously adding astragaloside IV to liquid A and liquid B, respectively, to obtain a shell spinning solution and a core spinning solution, wherein the mass concentration of the shell spinning solution is 10 mg / mL to 30 mg / mL, and the mass concentration of astragaloside IV in the shell layer is 10 mg / mL to 15 mg / mL; the mass concentration of the core layer spinning solution is 4 mg / mL to 8 mg / mL, and the mass concentration of astragaloside IV in the core layer is 6 mg / mL to 8 mg / mL; Step (2): the shell layer spinning solution and the core layer spinning solution in step (1) are respectively loaded into syringes, and the nanofibers formed by the shell layer spinning solution and the core layer spinning solution are spirally sprayed onto a receiving plate using the syringe to obtain a coaxial astragaloside nanofiber dressing; Step (3): dissolving sodium polyacrylate, polyvinyl pyrrolidone and polylactic acid in a mass ratio of (1-3): (1-4): (3-6) in a mixed solvent of chloroform and acetone to obtain a spinning solution I with a mass ratio of 20%; Step (4): fix the coaxial astragaloside nanofiber dressing prepared in step (2) on a receiving plate, suck the spinning solution I obtained in step (3) into a syringe, and use the syringe to spirally spray the nanofibers formed by the spinning solution onto the coaxial astragaloside nanofiber dressing on the receiving plate, so as to obtain a double-layer nanofiber functional dressing. During the spinning process, the voltage between the plates is 5 kV to 25 kV, the flow rate of the spinning solution I pumped by the propeller C is 0.01 mL / h to 5 mL / h, and the distance between the receiving plate and the spinneret is 5 cm to 25 cm.

2. The method for preparing a novel detachable double-layer nanofiber functional dressing according to claim 1, characterized in that: In step (2) and step (4), when spraying the nanofibers, a hose is used to connect the syringe and the coaxial needle, and the syringe and the coaxial needle are fixed on a flow pump, and the distance between the spinneret needle and the receiving plate is adjusted, and the high voltage power supply and the flow pump are turned on to complete the spraying of the nanofibers.

3. The method for preparing a novel detachable double-layer nanofiber functional dressing according to claim 1, characterized in that: In step (2) and step (4), when the nanofibers are sprayed, the voltage between the plates is 5 kV to 25 kV, the flow rate of the shell layer spinning solution pumped by propeller A is 0.01 mL / h to 5 mL / h, the flow rate of the core layer spinning solution pumped by propeller B is 0.01 mL / h to 5 mL / h, the flow rate of the spinning solution I pumped by propeller C is 0.01 mL / h to 5 mL / h, and the receiving distance is 5 cm-25 cm.

4. A novel detachable double-layer nanofiber functional dressing prepared by the preparation method described in any one of claims 1 to 3.

5. The novel detachable double-layer nanofiber functional dressing according to claim 4, characterized in that: The diameter of the lower layer nanofibers is 300-1000nm, and the diameter of the upper layer nanofibers is 200-700nm.

6. Use of a novel detachable double-layer nanofiber functional dressing prepared according to any one of claims 4 to 5 in promoting skin wound healing.

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