Temperature-responsive nanofiber membranes, methods of making and using the same

Abstract

The application provides a temperature-responsive nanofiber membrane and a preparation method and application thereof, and belongs to the technical field of medical antibacterial dressings, wherein the temperature-responsive nanofiber membrane comprises a nanofiber membrane formed by electrospinning of a temperature-responsive copolymer and an antibacterial agent distributed in the nanofiber membrane, wherein the temperature-responsive copolymer has a structure shown in formula (I) or formula (II); x = 100-500, y = 25-50, z = 25-50, and the lowest critical phase transition temperature of the temperature-responsive copolymer is below 37 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of medical antibacterial dressings, and particularly relates to a temperature-responsive nanofiber membrane, its preparation method, and its application. Background Technology

[0002] Various types of wounds, including acute postoperative wounds, abrasions, sharps injuries, penetrating injuries, and burns, remain a central clinical concern, significantly impacting patients and society. A key process during the wound healing response is the restoration of the epithelial layer to restore the integrity of the skin barrier. While various wound dressings, such as gauze, cotton wool, and hydrogels, are widely used, existing adhesive wound dressings are unsatisfactory in wound treatment due to their slow and passive healing behavior.

[0003] Wound management is a vital physiological process that includes hemostasis, cleaning, wound closure, and dressing. The first two steps can be completed within a predetermined timeframe and follow certain guidelines, while wound closure and dressing are more complex. In cases such as surgical wounds, the wound edges can merge, and wound healing typically relies on the intervention of disposable skin suture devices, clips, or sutures. However, time-consuming procedures not only require skilled surgeons but also inevitably damage surrounding healthy skin tissue, increasing the risk of scarring, infection, inflammation, and surgical complications. Although many novel, multifunctional dressings have proven effective in maintaining a moist microenvironment and accelerating wound healing through various pathways, few are capable of controlling wound closure.

[0004] Furthermore, most electrospun multifunctional polymers are currently only soluble in organic solvents such as chloroform, acetone, and N,N-dimethylformamide, which can irritate the skin and cannot be directly applied to wounds. Therefore, it is generally necessary to pre-spin the multifunctional polymer into a film and then apply it to the wound. This method of obtaining multifunctional dressings is rather cumbersome, and the resulting dressings pose certain potential hazards. Summary of the Invention

[0005] In view of the above, and to address the aforementioned technical problems, this invention provides a temperature-responsive nanofiber membrane, its preparation method, and its applications, aiming to at least partially solve the above-mentioned technical problems. The technical solution provided by this invention is as follows.

[0006] As a first aspect of the present invention, a temperature-responsive nanofiber membrane is provided, comprising a nanofiber membrane formed by electrospinning a temperature-responsive copolymer and an antibacterial agent distributed in the nanofiber membrane, wherein the temperature-responsive copolymer has a structure shown in formula (I) or formula (II):

[0007]

[0008] x = 100–500, y = 25–50, z = 25–50, wherein the minimum critical phase transformation temperature of the temperature-responsive copolymer is below 37°C.

[0009] As a second aspect of the present invention, a method for preparing a temperature-responsive nanofiber membrane is provided, comprising: dissolving a temperature-responsive copolymer in ethanol or medical acetone to obtain a first spinning solution; adding an antibacterial agent to the first spinning solution and dispersing it uniformly to obtain a second spinning solution; and performing electrospinning using the second spinning solution to obtain a temperature-responsive nanofiber membrane; wherein the temperature-responsive copolymer has the structure shown in formula (I) or formula (II):

[0010]

[0011] x=100~500, y=25~50, z=25~50.

[0012] As a third aspect of the invention, the application of a temperature-responsive nanofiber membrane in wound dressings is provided.

[0013] Based on the above technical solution, the temperature-responsive nanofiber membrane, its preparation method, and its application provided by the present invention have at least one of the following beneficial effects:

[0014] (1) In an embodiment of the present invention, a nanofiber membrane containing a temperature-responsive copolymer is formed by electrospinning. This nanofiber membrane contains a temperature-responsive monomer unit (N-isopropylacrylamide), a hydrophobic monomer unit (butyl methacrylate), and an adhesive functional group compound unit (dopamine or gallic acid). When the temperature exceeds the lowest critical phase inversion temperature (LCST), the copolymer segments change from an extended state to a contracted state. The temperature-induced contractile force is rapidly transmitted to the dynamic wound edge, resisting external forces and driving wound closure. The presence of the adhesive functional group gives the nanofiber membrane strong adhesive properties, and the strong tissue adhesion allows the nanofiber membrane dressing to adhere tightly to the wound. The presence of the hydrophobic monomer gives the nanofiber membrane a certain degree of waterproofing. An antibacterial agent is introduced into the nanofiber membrane to enhance its antibacterial properties. Therefore, the temperature-responsive nanofiber membrane provided by the present invention has antibacterial, temperature-responsive wound contraction, hemostatic, and adhesive functions, which can significantly promote wound contraction and reduce inflammatory response, thus promoting wound healing.

[0015] (2) In the embodiments of the present invention, the temperature-responsive polymer is dissolved in ethanol or medical acetone to make the prepared nanofiber membrane safer and less irritating to the skin or wound. Electrospinning technology is used to give the prepared fiber material good mechanical strength. At the same time, the high porosity of the fiber membrane not only allows for rapid absorption of wound exudate and maintenance of wound moisture, but also provides strong air permeability and prevents the penetration of external microorganisms. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of the temperature-responsive nanofiber membrane prepared in Example 1 of the present invention;

[0017] Figure 2 This is a diagram showing the mechanical tensile properties of the temperature-responsive nanofiber membrane in Example 1 of the present invention;

[0018] Figure 3 This is a thermal response analysis diagram of the temperature-responsive nanofiber membrane in Example 1 of the present invention;

[0019] Figure 4 This is a schematic diagram of in vivo thermal shrinkage wound healing using the temperature-responsive nanofiber membrane in Example 1 of the present invention;

[0020] Figure 5 This is a schematic diagram showing the wound healing status of the control group and the experimental group in the treatment of rat wounds with the temperature-responsive nanofiber membrane in Example 1 of the present invention within 14 days.

[0021] Figure 6 for Figure 5 A comparison of wound healing rates between the control group and the experimental group within 14 days, based on statistical data.

[0022] Figure 7 This is a scanning electron microscope image of the temperature-responsive nanofiber membrane prepared in Example 2 of the present invention;

[0023] Figure 8 This is a schematic diagram of in vivo thermal shrinkage wound healing using a temperature-responsive nanofiber membrane in Embodiment 2 of the present invention.

[0024] Figure 9 This is a comparison chart of the wound healing rates of the control group and the experimental group of the temperature-responsive nanofiber membrane in Example 2 of the present invention within 14 days.

[0025] Figure 10 This is a scanning electron microscope image of the temperature-responsive nanofiber membrane prepared in Example 3 of the present invention;

[0026] Figure 11 This is a schematic diagram of in vivo thermal shrinkage wound healing using the temperature-responsive nanofiber membrane in Example 3 of the present invention.

[0027] Figure 12 This is a comparison chart of the wound healing rates of the control group and the experimental group of the temperature-responsive nanofiber membrane in Example 3 of the present invention within 14 days. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] To address the issue that some functional polymers cannot effectively control wound closure, this invention introduces temperature-responsive copolymers into nanofiber membranes, promoting wound healing through edge contraction forces using a non-invasive method. Specifically, temperature-induced contraction forces are rapidly transmitted to the dynamic wound edge, resisting external forces and driving wound closure, effectively avoiding damage to surrounding healthy tissue and reducing the risk of scarring, infection, and inflammation caused by disposable skin sutures, clips, or stitches. Secondly, tissue adhesion is crucial. Wound contraction only occurs when there is a strong interaction between the biomaterial and the skin. To address this, this invention uses N-succinimide acrylate as an intermediate to graft compounds with adhesive functional groups onto the polymer chain, enhancing the adhesion of the nanofiber membrane and allowing the nanofibers to adhere tightly to the wound edge. Electrospinning is an emerging thin-film preparation technology. Fiber materials prepared by electrospinning possess good mechanical strength, and their three-dimensional structure is similar to the microstructure of the extracellular matrix, which is beneficial for cell proliferation and the growth of new tissues. Secondly, the high porosity allows this material to not only quickly absorb wound exudate and maintain wound moisture, but also provides excellent breathability and prevents the penetration of external microorganisms. Its high specific surface area enables rapid and effective hemostasis while preventing moisture loss, thus maintaining a stable, moist environment crucial for promoting wound healing. Furthermore, the electrospinning device is simple, easy to operate, and inexpensive. The filaments, produced by electrospinning, coagulate on the wound surface to form a fibrous membrane, enhancing the practicality of electrospinning in the preparation of wound dressings.

[0030] Specifically, in a first aspect, the present invention provides a temperature-responsive nanofiber membrane, comprising a nanofiber membrane formed by electrospinning a temperature-responsive copolymer and an antibacterial agent distributed in the nanofiber membrane, wherein the temperature-responsive copolymer has a structure shown in formula (I) or formula (II):

[0031]

[0032] x = 100–500, y = 25–50, z = 25–50, wherein the minimum critical phase transformation temperature of the temperature-responsive copolymer is below 37°C.

[0033] In embodiments of the present invention, a nanofiber membrane containing a temperature-responsive copolymer is formed by electrospinning. This nanofiber membrane contains a temperature-responsive monomer unit (N-isopropylacrylamide), a hydrophobic monomer unit (butyl methacrylate), and a compound unit containing an adhesive functional group (dopamine or gallic acid). When the temperature exceeds the lowest critical phase inversion temperature (LCST), the copolymer segments change from an extended state to a contracted state. The temperature-induced contractile force is rapidly transmitted to the wound edge, resisting external forces and promoting wound closure non-invasively. This effectively avoids damage to surrounding healthy tissue and avoids the risks of scarring, infection, and inflammation associated with traditional sutures and clip healing. The presence of the adhesive functional group in the temperature-responsive copolymer gives the nanofiber membrane strong adhesive properties. This strong tissue adhesion allows the nanofiber membrane dressing to adhere tightly to the wound, aiding in wound closure while preventing moisture loss and maintaining a stable moist environment. Introducing an antibacterial agent into the nanofiber membrane enhances its antibacterial properties. Therefore, the temperature-responsive nanofiber membrane provided by the present invention has antibacterial, temperature-responsive wound contraction, hemostatic and adhesive functions, which can significantly promote wound contraction and reduce inflammatory response, and promote wound healing.

[0034] According to embodiments of the present invention, the temperature-responsive nanofiber membrane of the present invention has temperature responsiveness and adhesiveness.

[0035] As a second aspect of the present invention, a method for preparing a temperature-responsive nanofiber membrane is provided, comprising: dissolving a temperature-responsive copolymer in ethanol or medical acetone to obtain a first spinning solution; adding an antibacterial agent to the first spinning solution and dispersing it uniformly to obtain a second spinning solution; and performing electrospinning using the second spinning solution to obtain a temperature-responsive nanofiber membrane; wherein the temperature-responsive copolymer has the structure shown in formula (I) or formula (II):

[0036]

[0037] x=100~500, y=25~50, z=25~50.

[0038] In the embodiments of this invention, most electrospun materials can only be dissolved in organic solvents such as chloroform and acetone, which can irritate the skin or wounds and cannot be directly applied to the wound. They generally need to be spun into a film first and then applied to the wound, a complex process requiring a high degree of wound area and regularity. However, the temperature-responsive copolymer in this application has good biocompatibility, dissolving in medical acetone or ethanol, and these solvents are harmless to the human body. By dispersing the temperature-responsive copolymer in an ethanol or medical acetone solution, followed by the addition of an antibacterial agent and electrospinning, a temperature-responsive, highly adhesive nanofiber membrane can be obtained. The method for preparing the nanofiber membrane in this invention is relatively simple, the preparation conditions are mild, and it is highly safe and pollution-free, making it a highly safe biomaterial suitable for clinical medical dressings.

[0039] According to an embodiment of the present invention, the concentration of the temperature-responsive copolymer in the first spinning solution is 5 wt% to 95 wt%, preferably 10 wt% to 40 wt%; the concentration of the antibacterial agent in the second spinning solution is 1 wt% to 50 wt%, preferably 1 wt% to 10 wt%. The antibacterial agent is zinc oxide nanoparticles, but other non-toxic and non-irritating compounds with antibacterial effects can also be used.

[0040] According to embodiments of the present invention, the voltage for electrospinning is 10-20 kV, the flow rate of the second spinning solution is 0.2-2 mL / h, and the distance between the electrospinning jetting device and the receiving object (such as a wound) is 5-20 cm. In embodiments of the present invention, by controlling the voltage and flow rate of the electrospinning solution, uniform and continuously filamentous nanowires can be obtained, which then coagulate on the wound surface to form a nanofiber membrane. The present invention utilizes electrospinning technology to perform in-situ spinning and membrane formation on the wound surface. The resulting nanofiber membrane is suitable for wounds of different properties, shapes, and areas, such as burns, abrasions, and sharps injuries. Furthermore, the material itself possesses certain tissue adhesion properties, allowing it to adhere well to the surface of complex wounds, thus solving the problem of limited size in traditional dressings.

[0041] According to an embodiment of the present invention, the preparation of a temperature-responsive polymer includes: dissolving an initiator, a thermosensitive monomer, a hydrophobic monomer, and N-succinimide acrylate in 1,4-dioxane, purging with an inert gas for protection, reacting at 60-80°C after multiple freeze-thaw cycles, and obtaining the temperature-responsive polymer after purification and drying.

[0042] In embodiments of the present invention, an initiator, a thermosensitive monomer, a hydrophobic monomer, and N-succinimidyl acrylate are reacted to obtain a temperature-responsive polymer. The inert gas can be nitrogen or argon. The polymerization reaction time is 8–12 hours, and purification is achieved by subjecting the polymerization product to multiple sedimentations in diethyl ether or n-hexane to obtain a relatively pure temperature-responsive polymer. Further, the initiator is selected from any one of azobisisobutyronitrile, dimethyl azobisisobutyrate, and benzoyl peroxide; the thermosensitive monomer is selected from N-isopropylacrylamide, and the hydrophobic monomer is selected from butyl methacrylate. The molar ratio of the initiator, thermosensitive monomer, hydrophobic monomer, and N-succinimidyl acrylate is 1:(100–500):(25–50):(25–50).

[0043] According to an embodiment of the present invention, the prepared temperature-responsive polymer is further dissolved in an organic solvent, and triethylamine and a compound containing adhesive functional groups are added for blending. An inert gas is introduced for protection, and after multiple freeze-thaw cycles, a polymerization reaction is carried out at room temperature. After purification and drying, a temperature-responsive copolymer is obtained. The polymerization reaction time is 8–12 hours, and the polymerization reaction can be a reversible addition-fragmentation chain transfer polymerization or an atom transfer radical polymerization method. The molar ratio of the temperature-responsive polymer, triethylamine, and the compound containing adhesive functional groups is 1:1:(1–2); the compound containing adhesive functional groups is selected from dopamine hydrochloride or gallic acid.

[0044] In an embodiment of the present invention, in the presence of triethylamine, a temperature-responsive polymer is polymerized with a compound containing adhesive functional groups. During the reaction, the acrylate-N-succinimide ester group in the temperature-responsive polymer acts as an intermediate and is grafted onto the compound containing adhesive functional groups, thereby obtaining a temperature-responsive copolymer.

[0045] According to embodiments of the present invention, the present invention also provides the application of a temperature-responsive nanofiber membrane in wound dressings.

[0046] In the embodiments of the present invention, the temperature-responsive and strongly adhesive nanofiber membrane provided by the present invention has a stable structure, strong practicality, and high potential for clinical and market applications, and can be used as a wound dressing.

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are only some embodiments of the present invention.

[0048] Example 1

[0049] The preparation of temperature-responsive copolymers includes the following steps:

[0050] Step 1: Accurately weigh 2.0 g N-isopropylacrylamide, 0.25 g butyl methacrylate, and 0.42 g N-succinimidyl acrylate, wherein the molar ratio of N-isopropylacrylamide, butyl methacrylate, and N-succinimidyl acrylate is 250:25:25. Add these to a 25 mL polymerization flask, then add 2 mL of 1,4-dioxane and dissolve completely. Stir under nitrogen for 20 min, then add 9.6 mg of 4-cyano-4-(phenylcarbonylthio)pentanoic acid. After three freeze-thaw cycles, react at 60–80 °C for 8–12 hours. The resulting product is precipitated three times in diethyl ether or n-hexane, and then vacuum dried to obtain the temperature-responsive polymer.

[0051] Step 2: Weigh 1g of the temperature-responsive polymer obtained in Step 1, dissolve it in 15mL of dichloromethane, then add 0.18g of triethylamine and 0.17g of dopamine hydrochloride, dissolve completely, purge with argon gas, and react at room temperature for 12 hours. The resulting product is precipitated twice in diethyl ether or n-hexane, and after vacuum drying, the temperature-responsive copolymer (named PNB-DOPA) is obtained.

[0052] The preparation of temperature-responsive nanofiber membranes includes the following steps:

[0053] Step 1: Preparation of the first spinning solution: Dissolve 1g of the obtained temperature-responsive copolymer PNB-DOPA in 4mL of ethanol to obtain the PNB-DOPA copolymer spinning solution. The concentration of PNB-DOPA copolymer in ethanol is about 25wt%.

[0054] Step 2: Preparation of the second spinning solution: 0.12 g of zinc oxide nanoparticles were added to the PNB-DOPA copolymer spinning solution and stirred for 12 hours to ensure thorough and uniform dispersion, thus obtaining the PNB-DOPA-zinc oxide spinning solution. The concentration of zinc oxide in the second spinning solution was approximately 3 wt%.

[0055] Step 3: Preparation of electrospun fiber membrane: PNB-DOPA-zinc oxide spinning solution was added to a 5mL syringe. Electrospinning was performed in situ using a 10kV handheld electrospinner with a distance of approximately 10cm between the spinneret and the receiver. The resulting temperature-responsive nanofiber membrane is shown below. Figure 1 As shown.

[0056] Furthermore, the obtained temperature-responsive nanofiber membrane was subjected to relevant mechanical property tests.

[0057] Figure 2 This is a diagram showing the mechanical tensile properties of the temperature-responsive nanofiber membrane in Example 1 of the present invention.

[0058] like Figure 2 As shown, the tensile stress of the temperature-responsive nanofiber membrane prepared by electrospinning can reach 2.1 MPa, indicating that the temperature-responsive fiber membrane prepared by electrospinning in Example 1 has good mechanical tensile properties.

[0059] Furthermore, in order to evaluate the thermal shrinkage performance of the temperature-responsive nanofiber membrane prepared by electrospinning according to the present invention, a thermal responsiveness analysis was performed on the temperature-responsive, highly adhesive nanofiber membrane (PNB-DOPA), as detailed below.

[0060] Temperature-responsive nanofiber membranes prepared by electrospinning were placed in water at 37°C (approximate to a real-world environment), and their area was measured at a specific time. The relationship between membrane area shrinkage capacity and time was obtained. Specific test results are as follows: Figure 3 As shown.

[0061] Figure 3 This is a thermal response analysis diagram of the temperature-responsive nanofiber membrane in Example 1 of the present invention.

[0062] like Figure 3 As shown, in the first 30 minutes, PNB-DOPA exhibited rapid shrinkage, with the remaining area being approximately 20% of the original state. It eventually shrank to a denser state, with the remaining area being 18%.

[0063] Based on the aforementioned strong tissue adhesion, thermal shrinkage, and mechanical properties, it is demonstrated that this material has the potential for use in non-invasive wound closure. Therefore, the next step is to conduct in vivo thermal shrinkage wound healing experiments on the temperature-responsive nanofiber membrane. The specific procedure is as follows:

[0064] A 2 cm full-thickness incision was created along the midline of the spine in mice. All mice were randomly divided into two groups: a control group treated with an adhesive commercial film, and an experimental group treated with thermoresponsive PNB-DOPA, where the thermoresponsive nanofiber membrane was spun in situ onto the incision. After 24 hours, all dressings were gently peeled off the wound, and the wound width was recorded to evaluate wound closure. Specific test results are as follows: Figure 4 As shown. It should be noted that the in vivo mouse experiments of this invention comply with relevant laws and regulations.

[0065] Figure 4 This is a schematic diagram of in vivo thermal shrinkage wound healing using a temperature-responsive nanofiber membrane in Example 1 of the present invention.

[0066] like Figure 4As shown, the two groups of wounds exhibited different appearances. Specifically, the wound condition in the adhesive commercial film group (control group) was even worse, with the wound width increasing. Compared to the control group, PNB-DOPA (experimental group) demonstrated excellent wound contraction ability, with the wound area shrinking to 20% of its original state, which is consistent with its thermal response volume change results.

[0067] Furthermore, to verify the healing effect of the electrospun temperature-responsive nanofiber membrane prepared in Example 1 of the present invention on bacterial infected wounds, i.e., an in vivo full-thickness wound healing test, the specific test process is as follows.

[0068] Mice were anesthetized and shaved. A 2-cm full-thickness incision was made on the rump and back of each mouse using surgical scissors. Staphylococcus aureus bacterial solution was applied to the wound to successfully infect it with Staphylococcus aureus. Each experiment was conducted in 6 replicates. The wound area was measured and photographed on days 0, 4, 8, 12, and 14. Figures 5-6 As shown.

[0069] Figure 5 This is a schematic diagram showing the wound healing status of the control group and the experimental group in the treatment of rat wounds with temperature-responsive nanofiber membranes according to Example 1 of the present invention within 14 days.

[0070] like Figure 5 As shown, the wounds of the rats in the experimental group healed significantly better than those in the control group over time, with almost all wounds healed by day 14 and significant regeneration of new epidermis; in contrast, the skin wounds of the control group had a smaller healing area and obvious wound gaps after 14 days.

[0071] Figure 6 for Figure 5 The chart compares the wound healing rates of the control group and the experimental group within 14 days. The wound healing rate is calculated as: (original wound area - current measured area) / original wound area * 100%.

[0072] like Figure 6 As shown, the wound healing rate in the experimental group was significantly higher than that in the control group, and the healing rate approached 100% on day 14. In contrast, the wound healing rate in the control group was around 80%. This indicates that, under the same time conditions, the experimental group showed significantly better wound healing. In conclusion, these results demonstrate that electrospun temperature-responsive nanofiber membranes with thermal shrinkage and tissue adhesion can effectively achieve wound healing.

[0073] Example 2

[0074] The preparation of temperature-responsive copolymers includes the following steps:

[0075] Step 1: Accurately weigh 4.0 g N-isopropylacrylamide, 0.50 g butyl methacrylate, and 0.60 g N-succinimidyl acrylate, wherein the molar ratio of N-isopropylacrylamide, butyl methacrylate, and N-succinimidyl acrylate is 300:30:30. Then, add these components to a 50 mL polymerization flask, followed by 8 mL of 1,4-dioxane. Dissolve completely, stir under nitrogen atmosphere for 20 min, then add 32.8 mg of 4-cyano-4-(phenylcarbonylthio)pentanoic acid. After three freeze-thaw cycles, react at 60–80 °C for 8–12 hours. The resulting product is precipitated three times in diethyl ether or n-hexane, and then vacuum dried to obtain the temperature-responsive polymer.

[0076] Step 2: Take 2g of the temperature-responsive polymer obtained in Step 1, dissolve it in 25mL of dichloromethane, then add 0.36g of triethylamine and 0.34g of gallic acid, dissolve completely, purge with argon gas, and react at room temperature for 12 hours. The resulting product is precipitated twice in diethyl ether or n-hexane, and then dried under vacuum to obtain the temperature-responsive copolymer (named PNB-GA).

[0077] The preparation of temperature-responsive nanofiber membranes includes the following steps:

[0078] Step 1: Preparation of the first spinning solution: Dissolve 1g of the obtained temperature-responsive copolymer PNB-GA in 3mL of ethanol to obtain the PNB-GA copolymer spinning solution. The concentration of PNB-GA copolymer in ethanol is about 25wt%.

[0079] Step 2: Prepare the second spinning solution: Add 0.1g of zinc oxide nanoparticles to the PNB-GA copolymer spinning solution and stir for 12 hours to fully and uniformly disperse the solution, thus obtaining the PNB-GA-zinc oxide spinning solution. The concentration of zinc oxide in the second spinning solution is about 3wt%.

[0080] Step 3: Preparation of electrospun fiber membrane: PNB-GA-zinc oxide spinning solution was added to a 5mL syringe. Using a handheld electrospinning apparatus with a voltage of 10kV, an electrospun fiber membrane could be formed in situ at a distance of approximately 10cm between the spinneret and the receiver. Figure 7 As shown.

[0081] Figure 7 This is a scanning electron microscope image of the temperature-responsive nanofiber membrane prepared in Example 2 of the present invention.

[0082] like Figure 7 As shown, the temperature-responsive nanofiber membrane prepared by electrospinning in Example 2 is continuous, has a smooth surface, and has uniform nanofiber diameter.

[0083] Furthermore, using the same method as in Example 1, a thermal shrinkage wound healing experiment was conducted in vivo using a temperature-responsive nanofiber membrane. Specific test results are as follows: Figure 8 As shown.

[0084] Figure 8 This is a schematic diagram of in vivo thermal shrinkage wound healing using a temperature-responsive nanofiber membrane in Example 2 of the present invention.

[0085] like Figure 8 As shown, after 24 hours, the wound condition in the adhesive commercial film group even worsened, with the wound width increasing. Compared with the control group, PNB-GA exhibited superior wound contraction ability and reduced wound width.

[0086] Figure 9 This is a comparison chart of the wound healing rates of the control group and the experimental group of the temperature-responsive nanofiber membrane in Example 2 of the present invention within 14 days.

[0087] like Figure 9 As shown, the wound healing rate in the experimental group was significantly higher than that in the control group, and the healing rate approached 100% on day 14. In contrast, the wound healing rate in the control group was around 78%. This demonstrates that, under the same time conditions, the experimental group exhibited significantly better wound healing.

[0088] Example 3

[0089] Step 1: Accurately weigh 2.0 g of N-isopropylacrylamide and 0.25 g of butyl methacrylate, wherein the molar ratio of N-isopropylacrylamide to butyl methacrylate is 250:25. Then, add them to a 25 mL polymerization flask according to the ratio, followed by 2 mL of isopropanol / water, and dissolve completely. Stir under nitrogen purging for 20 min, then add 14 mg of ethyl 2-bromo-2-methylpropionate. After three freeze-thaw cycles, react at room temperature for 48 hours. The resulting product is precipitated three times in diethyl ether or n-hexane, and then vacuum dried to obtain temperature-responsive polymer 1.

[0090] Step 2: Dissolve 1.5g of the temperature-responsive polymer obtained in Step 1 in 3ml of N,N-dimethylformamide, then add 0.42g of N-succinimide acrylate, dissolve completely, purge with nitrogen for protection, and react at 60-80℃ for 8h after three freeze-thaw cycles. The resulting product is precipitated three times in diethyl ether or n-hexane, and then dried under vacuum to obtain temperature-responsive polymer 2.

[0091] Step 3: Dissolve 1g of the temperature-responsive polymer 2 obtained in Step 2 in 15mL of dichloromethane, then add 0.18g of triethylamine and 0.17g of dopamine hydrochloride, dissolve completely, purge with argon gas, and react at room temperature for 12 hours. The resulting product is precipitated twice in diethyl ether or n-hexane, and then dried under vacuum to obtain the temperature-responsive copolymer (named PNB-DOPA).

[0092] The preparation of temperature-responsive nanofiber membranes includes the following steps:

[0093] Step 1: Preparation of spinning solution: Dissolve 1g of the obtained temperature-responsive copolymer PNB-DOPA in 4mL of ethanol to obtain the PNB-DOPA copolymer spinning solution. The concentration of PNB-DOPA copolymer in ethanol is about 25wt%.

[0094] Step 2: Preparation of electrospun fiber membrane: PNB-DOPA-zinc oxide spinning solution was added to a 5 mL syringe. Using a handheld electrospinning apparatus with a voltage of 10 kV, electrospinning was performed in situ at a distance of approximately 10 cm between the spinneret and the receiver to form a fiber membrane. Example 3 employed an atom transfer radical polymerization method, and the temperature-responsive nanofiber membrane prepared by electrospinning was as follows... Figure 10 As shown.

[0095] Figure 10 This is a scanning electron microscope image of the temperature-responsive nanofiber membrane prepared in Example 3 of the present invention.

[0096] like Figure 10 As shown, the temperature-responsive nanofiber membrane prepared in Example 3 is continuous and the nanofiber diameter is uniform.

[0097] Figure 11 This is a schematic diagram of in vivo thermal shrinkage wound healing using a temperature-responsive nanofiber membrane in Example 3 of the present invention.

[0098] like Figure 11 As shown, after 24 hours, the wounds in the adhesive commercial film group did not shrink; in fact, the wound condition worsened. Compared to the control group, PNB-DOPA exhibited superior wound contraction ability, promoting wound contraction.

[0099] Figure 12 This is a comparison chart of the wound healing rates of the control group and the experimental group of the temperature-responsive nanofiber membrane in Example 3 of the present invention within 14 days.

[0100] like Figure 12 As shown, the wound healing rate in the experimental group was significantly higher than that in the control group, with the healing rate approaching 95% by day 14. In contrast, the wound healing rate in the control group was around 70%. This demonstrates that, under the same time conditions, the experimental group exhibited significantly better wound healing.

[0101] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a temperature-responsive nanofiber membrane, comprising: The initiator, thermosensitive monomer, hydrophobic monomer, and N-succinimide acrylate were dissolved in 1,4-dioxane, protected by an inert gas, and reacted at 60-80°C after multiple freeze-thaw cycles. The resulting temperature-responsive polymer was obtained after purification and drying. The temperature-responsive polymer was dissolved in an organic solvent, and triethylamine and a compound containing adhesive functional groups were added for blending. An inert gas was introduced for protection, and after multiple freeze-thaw cycles, a polymerization reaction was carried out at room temperature. After purification and drying, the temperature-responsive copolymer was obtained. The temperature-responsive copolymer is dissolved in ethanol or medical acetone to obtain a first spinning solution; An antibacterial agent is added to the first spinning solution and dispersed evenly to obtain a second spinning solution. Electrospinning is performed using the second spinning solution to obtain a temperature-responsive nanofiber membrane. The molar ratio of the initiator, thermosensitive monomer, hydrophobic monomer, and N-succinimide acrylate is 1:(100~500):(25~50):(25~50). The molar ratio of the temperature-responsive polymer, triethylamine, and the compound containing adhesive functional groups is 1:1:(1~2). The temperature-responsive copolymer has a minimum critical phase inversion temperature below 37°C and has the structure shown in formula (I) or formula (II): Formula (I) or Formula (II); x=100~500, y=25~50, z=25~50.

2. The method according to claim 1, wherein, The concentration of the temperature-responsive copolymer in the first spinning solution is 5wt% to 95wt%, and the concentration of the antibacterial agent in the second spinning solution is 1wt% to 50wt%.

3. The method according to claim 1, wherein, The antibacterial agent includes zinc oxide nanoparticles; The voltage for electrospinning is 10~20kV, the flow rate of the second spinning solution is 0.2~2mL / h, and the distance between the electrospinning jet device and the receiving material is 5~20cm.

4. The method according to claim 1, wherein, The initiator is selected from any one of azobisisobutyronitrile, dimethyl azobisisobutyrate, and benzoyl peroxide; The thermosensitive monomer is selected from N-isopropylacrylamide; The hydrophobic monomer is selected from butyl methacrylate; The compound containing the adhesive functional group is selected from dopamine hydrochloride or gallic acid.

5. A temperature-responsive nanofiber membrane prepared by any one of claims 1-4, comprising a nanofiber membrane formed by electrospinning a temperature-responsive copolymer and an antibacterial agent distributed in the nanofiber membrane, wherein the temperature-responsive nanofiber membrane has temperature responsiveness and adhesiveness; in, The temperature-responsive copolymer is soluble in ethanol or medical acetone and has the structure shown in formula (I) or formula (II): Formula (I) or Formula (II); x=100~500, y=25~50, z=25~50, The minimum critical phase transformation temperature of the temperature-responsive copolymer is below 37°C.

6. The application of the temperature-responsive nanofiber membrane as described in claim 5 in wound dressings.

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