A thermo-induced heat-shrinkable fiber dressing, its preparation and application

Abstract

This invention relates to a thermo-induced heat-shrinkable fiber dressing, its preparation, and its application. The fiber dressing comprises a nanofiber membrane formed from aqueous polyurethane and a rigid polymer. The prepared thermo-induced heat-shrinkable fiber dressing undergoes heat shrinkage at 37°C, with a shrinkage rate of 10-80% after heating for 30 min to 24 h. The dressing exhibits high tensile strength of 5-30 MPa, high elongation at break of 50-400%, and high Young's modulus of 20-100 MPa. The thermo-induced heat-shrinkable dressing can induce mechanical contraction of the skin around a rat wound, promoting wound closure and repair. The method of this invention is simple and easy to implement, and the resulting dressing has excellent performance and great application prospects in the field of medical dressings.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials, and specifically relates to a body temperature-induced heat-shrinkable fiber dressing and its preparation and application. Background Technology

[0002] War, traffic accidents, and diseases often cause skin trauma, and improper wound treatment can even be life-threatening. Skin dressings, as an effective method of wound care, are key to promoting wound healing and reducing scar formation. In recent years, electrospun nanofiber materials have shown great potential in wound repair due to their ability to highly mimic the natural extracellular matrix, facilitating cell adhesion, offering good structural tunability, and high porosity. However, the following problems are common: First, dressings have poor wound healing promotion capabilities. Shortening wound closure time and improving healing outcomes are current research focuses for skin dressings. Currently reported repair-promoting technologies mostly employ bio-induction methods, loading functional drugs and growth factors onto materials. The release of these drugs or factors at the wound site achieves hemostasis, anti-inflammation, and tissue regeneration. However, this method often faces problems such as low drug loading capacity, drug side effects, demanding dressing storage conditions, and short effective time. In recent years, methods utilizing the mechanical contraction properties of dressings to induce wound closure have attracted widespread attention.

[0003] Secondly, nanofiber dressings have poor mechanical properties. The skin around human joints often needs to withstand significant deformation, with tensile strain of approximately 60-75%. Currently available fiber skin dressings generally have poor mechanical properties, and when applied to the skin around joints, they are subject to long-term cyclic stretching, easily leading to deformation and failure to maintain a close fit with the skin, resulting in functional impairment. Therefore, there is an urgent need to develop nanofiber dressings that combine strong mechanical properties with high efficiency in promoting wound healing. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a body temperature induced heat shrinkage fiber dressing and its preparation and application, overcoming the poor wound closure ability and poor mechanical properties of existing skin dressings, which make it difficult to meet the application requirements of joint wound repair.

[0005] The present invention provides a body temperature-induced heat-shrinkable fiber dressing, the fiber dressing comprising a nanofiber membrane formed of aqueous polyurethane and a rigid polymer.

[0006] Preferably, the soft segment of the waterborne polyurethane is one of polypropylene glycol, polyethylene glycol, polytetrahydrofuran glycol, polycaprolactone glycol, and polycarbonate glycol, and the hard segment is one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, with a hard segment / soft segment molar ratio (R value) of 1.0 to 1.2; the rigid polymer is one or more of polyvinyl butyral, polytetrafluoroethylene, polyvinyl chloride, and polystyrene.

[0007] Preferably, the body temperature-induced heat-shrinkable nanofiber dressing has a thickness of 20-100 μm, an average diameter of 100-600 nm, a Young's modulus of 20-100 MPa, a tensile strength of 5-30 MPa, and an elongation at break of 50-400%.

[0008] Preferably, the body temperature-induced heat-shrinkable nanofiber dressing shrinks by 10% to 80% when heated at 37°C for 30 min to 24 h.

[0009] More preferably, the body temperature-induced heat-shrinkable nanofiber dressing, when heated at 37°C in an in vitro rat wound closure experiment, showed a wound closure rate of 5-50% after 1-12 hours.

[0010] The present invention provides a method for preparing a body temperature-induced heat-shrinkable fiber dressing, comprising:

[0011] Aqueous polyurethane, rigid polymer, and solvent are mixed to obtain a spinning solution, which is then electrospun and dried to obtain a nanofiber membrane.

[0012] Preferably, the soft segment of the waterborne polyurethane is one of polypropylene glycol, polyethylene glycol, polytetrahydrofuran glycol, polycaprolactone glycol, and polycarbonate glycol, and the hard segment is one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The hard segment / soft segment molar ratio (R value) is 1.0 to 1.2. If the specific gravity is higher than this range, the waterborne polyurethane is prone to agglomeration and precipitation, making spinning impossible. If the specific gravity is lower than this range, the stretching of the waterborne polyurethane molecular chains during spinning is insufficient, and shrinkage cannot occur.

[0013] Preferably, the rigid polymer is one or more of polyvinyl butyral, polytetrafluoroethylene, polyvinyl chloride, and polystyrene.

[0014] Preferably, the solvent is one or more of water, ethanol, hexafluoroisopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, acetone, and tetrahydrofuran.

[0015] Preferably, the total concentration of waterborne polyurethane and rigid polymer in the spinning solution is 5-30 wt%. The amount of polymer concentration should not be too much or too little. If it is higher or lower than the set range, it will affect the spinning process and the fiber membrane effect will not achieve the expected goal.

[0016] Preferably, the mass ratio of the waterborne polyurethane to the rigid polymer is 8:2 to 2:8. If the mass ratio is higher than this range, the rigid polymer has a weak fixing effect on the waterborne polyurethane molecular chains, the stretched molecular chains relax, the energy stored in the fiber is small, and the shrinkage performance is poor. If the mass ratio is lower than this range, the molecular chains of the fiber do not elongate sufficiently after curing, the stored energy is small, and it is insufficient to produce shrinkage behavior under body temperature stimulation.

[0017] Preferably, the electrospinning process parameters are as follows: the spinning voltage is 10-40kV. If it is lower than this voltage range, the generated electric field force is insufficient to exert a strong stretching effect on the molecular chain, resulting in poor shrinkage performance; the receiving distance is 10-20cm; the infusion rate is 1-5mL / h; the temperature is 20-25℃; and the relative humidity is 35-60%.

[0018] Preferably, the drying time is 1 hour to 2 hours.

[0019] Preferably, the drying is vacuum drying at room temperature. Vacuum drying is used to accelerate solvent evaporation and reduce the impact of solvent residue on biocompatibility; room temperature drying is used to prevent the fiber membrane from shrinking during the drying process, which would affect its subsequent performance.

[0020] The present invention relates to the application of the body temperature-induced heat-shrinkable fiber dressing in the preparation of wound healing dressings.

[0021] This invention utilizes an electrospinning method involving the blending of waterborne polyurethane and a rigid polymer. Under body temperature stimulation, the stretched molecular chains in an electrostatic field retract, generating mechanical contraction force that induces wound closure. The preparation method is simple and easy to operate, resulting in a high wound closure rate. Electrospinning uses an electrostatic field to orient and stretch the molecular chains. The soft segments of waterborne polyurethane readily exhibit high elongation under a high-voltage electric field. After curing into fibers, the rigid polymer fixes the stretched polyurethane molecular chains, storing significant internal stress within the fibers. Under body temperature stimulation, the stretched polyurethane molecular chains contract, causing the rigid polymer to shrink, ultimately resulting in the shape contraction of the fiber membrane. Applying this fiber membrane to wounds utilizes its contraction property under body temperature, stretching the surrounding skin towards the center of the wound and accelerating wound closure. In addition, the combination of waterborne polyurethane and rigid polymers can mimic the "soft-hard" network structure of the dermis, giving the fiber membrane excellent elongation and mechanical strength. When applied to joint wounds, it can ensure dynamic adhesion to the skin. At the same time, the introduction of rigid polymers with high Young's modulus helps to improve the shrinkage force during heat shrinkage, which has broad application prospects in medical dressings.

[0022] The thermo-induced thermal shrinkage nanofibers of this invention are made from water-based polyurethane and rigid polymers; the thermo-induced thermal shrinkage fiber dressing has high strength, rigidity and ductility; the thermo-induced thermal shrinkage nanofiber dressing will thermally shrink under body temperature stimulation, causing the skin around the wound to contract and close the wound surface.

[0023] Beneficial effects

[0024] (1) The preparation method of the body temperature induced heat shrinkage nanofiber dressing of the present invention is simple and easy to operate and has low cost.

[0025] (2) The body temperature-induced thermal shrinkage nanofiber dressing of the present invention utilizes the high electrostatic force during electrospinning to stretch the molecular chains of waterborne polyurethane. The rigid polymer fixes the stretched molecular chains, and after solidification into fibers, a large amount of energy is stored in the fibers. Under the stimulation of body temperature, the molecular chains absorb heat and buckle, causing the fiber membrane to shrink and drive the skin around the wound to shrink towards the center. The entire system has no chemical reaction, only physical reaction. This design greatly improves the mobility of the molecular chains and accelerates wound closure to a great extent.

[0026] (3) The body temperature-induced thermal shrinkage nanofibers of the present invention are electrospun fiber membranes prepared from aqueous polyurethane and rigid polymers, which endow the dressing with super mechanical strength and high ductility, and are suitable for large deformation wounds such as joints. They can significantly improve the fatigue resistance and durability of the dressing material and extend its service life. At the same time, the introduction of rigid polymers gives the dressing a high elastic modulus, which helps to improve the shrinkage force and enhance the wound closure efficiency in actual use. Attached Figure Description

[0027] Figure 1 These are images of the body temperature-induced heat-shrinkable nanofiber dressing of the present invention after heating at 37°C for 0 hours and 12 hours;

[0028] Figure 2 These are images of the body temperature-induced thermal shrinkage nanofiber dressing of the present invention after heating at 37°C for 12 hours in an in vitro rat wound closure experiment;

[0029] Figure 3 This is the tensile fracture curve of the nanofiber dressing of the present invention. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0031] Mechanical property testing: During the test, the sample was cut into a rectangle with a length of 30mm and a width of 10mm for mechanical testing, and the tensile speed was 40mm / min.

[0032] Example 1

[0033] The preparation method of body temperature-induced heat-shrinkable nanofiber dressing includes the following steps:

[0034] (1) Using ethanol as solvent, the selected waterborne polyurethane soft segment is polyoxypropylene glycol, the hard segment is isophorone diisocyanate, the hard segment / soft segment molar ratio (R value) is 1.1, the waterborne polyurethane and polyvinyl butyral are dissolved in a mass ratio of 1:1, stirred evenly, and the precursor spinning solution is prepared; the solution concentration is 5wt%.

[0035] (2) Place the precursor spinning solution prepared in step (1) into a syringe and perform electrospinning to obtain a fiber membrane. The electrospinning process is as follows: the spinning voltage is 30kV, the receiving distance is 15cm, the infusion rate is 3mL / h, the temperature is 25±2℃, and the relative humidity is 50±5%.

[0036] (3) The composite fiber membrane was placed in an oven and vacuum dried at room temperature for 1 hour to remove residual solvent, thus obtaining nanofiber dressing.

[0037] like Figure 1 As shown, the final nanofiber dressing, after being heated at 37°C for 12 hours, exhibited a shrinkage rate of 70%; Figure 2 As shown, in the in vitro rat wound closure experiment, the wound closure rate was 36.8% after heating at 37℃ for 12 hours;

[0038] The nanofiber dressing had a thickness of 40 μm and an average diameter of 485 nm. During testing, the sample was cut into a rectangle 30 mm long and 10 mm wide for mechanical testing at a tensile speed of 40 mm / min. Figure 3 As shown, the tensile strength was 16.2 MPa, the elongation at break was 168.8%, and the Young's modulus was 90.6 MPa. In vivo validation was performed using a rat full-thickness skin defect model, and it was found that the wound healing rate was 30.8% after one day.

[0039] Comparative Example 1

[0040] A method for preparing a skin dressing is basically the same as in Example 1, except that the mass ratio of waterborne polyurethane to polyvinyl butyral in step (1) is 1:9. The final skin dressing, after being heated at 37°C for 12 hours, has a shrinkage rate of 10%, a thickness of 55 μm, an average diameter of 290 nm, a tensile strength of 3.5 MPa, an elongation at break of 30%, and a Young's modulus of 70 MPa. Comparing Comparative Example 1 with Example 1, it can be seen that the heat shrinkage rate in the Comparative Example is due to the reduced proportion of waterborne polyurethane, which leads to insufficient stretching of the molecular chains during spinning, resulting in less energy stored in the fiber. Furthermore, the rigid chains of polyvinyl butyral restrict the movement of the waterborne polyurethane molecular chains, preventing shrinkage. At the same time, the tensile strength and elongation at break are significantly lower than in Example 1, because the reduced proportion of waterborne polyurethane causes a decrease in tensile mechanics.

[0041] Comparative Example 2

[0042] A method for preparing a skin dressing is basically the same as in Example 1, except that the mass ratio of waterborne polyurethane to polyvinyl butyral in step (1) is 9:1. The final skin dressing, after being heated at 37°C for 12 hours, has a shrinkage rate of 65%, a thickness of 30 μm, an average diameter of 500 nm, a tensile strength of 15 MPa, an elongation at break of 220%, and a Young's modulus of 20 MPa. Comparing Comparative Example 2 with Example 1, it can be seen that the shrinkage rate of the skin dressing in the comparative example after heating at 37°C for 12 hours is significantly lower than that in Example 1. This is because the proportion of the rigid polymer polyvinyl butyral is reduced, and the rigid polymer does not fix the waterborne polyurethane molecular chains sufficiently, causing the waterborne polyurethane molecular chains to relax, resulting in less energy stored in the fibers, thus reducing the shrinkage rate. At the same time, the Young's modulus is significantly lower than that in Example 1. This is because the proportion of waterborne polyurethane is increased, the stiffness of the fiber membrane decreases, and the contractile force of the fiber membrane also decreases, reducing the tensile force on the wound skin.

[0043] Example 2

[0044] The preparation method of body temperature-induced heat-shrinkable nanofiber dressing includes the following steps:

[0045] (1) Using ethanol as solvent, the selected waterborne polyurethane soft segment is polyoxypropylene glycol, the selected hard segment is isophorone diisocyanate, the hard segment / soft segment molar ratio (R value) is 1.1, the waterborne polyurethane and polyvinyl butyral are dissolved in a mass ratio of 1:1, stirred evenly, and the precursor spinning solution is prepared; the concentration of waterborne polyurethane and polyvinyl butyral is 5wt%.

[0046] (2) Place the precursor spinning solution prepared in step (1) into a syringe and perform electrospinning to obtain a fiber membrane. The electrospinning process is as follows: the spinning voltage is 10kV, the receiving distance is 15cm, the infusion rate is 3mL / h, the temperature is 25±5℃, and the relative humidity is 40±5%.

[0047] (3) The composite fiber membrane was placed in an oven and vacuum dried at room temperature for 1 hour to remove residual solvent, thus obtaining a body temperature induced heat shrinkage nanofiber dressing.

[0048] The final thermo-induced thermal shrinkage nanofiber dressing showed a shrinkage rate of 55% after heating at 37℃ for 12 hours; in an in vitro rat wound closure experiment, the wound closure rate was 15% after heating at 37℃ for 12 hours.

[0049] It has a thickness of 30 μm, an average diameter of 650 nm, a tensile strength of 18 MPa, an elongation at break of 120%, and a Young's modulus of 100 MPa.

[0050] Example 3

[0051] The preparation method of body temperature-induced heat-shrinkable nanofiber dressing includes the following steps:

[0052] (1) Using ethanol as solvent, the selected waterborne polyurethane soft segment is polyoxypropylene glycol, the hard segment is isophorone diisocyanate, the hard segment / soft segment molar ratio (R value) is 1.1, the waterborne polyurethane and polyvinyl butyral are dissolved in a mass ratio of 1:1, stirred evenly, and the precursor spinning solution is prepared.

[0053] (2) Place the precursor spinning solution prepared in step (1) into a syringe and perform electrospinning to obtain a fiber membrane. The electrospinning process is as follows: the spinning voltage is 20kV, the receiving distance is 15cm, the infusion rate is 3mL / h, the temperature is 25±5℃, and the relative humidity is 55±5%.

[0054] (3) The composite fiber membrane was placed in an oven and vacuum dried at room temperature for 2 hours to remove residual solvent, thus obtaining a body temperature induced heat shrinkage nanofiber dressing.

[0055] The final thermo-induced thermal shrinkage nanofiber dressing showed a shrinkage rate of 68% after heating at 37℃ for 12 hours; in an in vitro rat wound closure experiment, the wound closure rate was 30% after heating at 37℃ for 12 hours.

[0056] It has a thickness of 35 μm, an average diameter of 520 nm, a tensile strength of 15 MPa, an elongation at break of 150%, and a Young's modulus of 80 MPa.

Claims

1. A body temperature-induced heat-shrinkable fiber dressing, characterized in that, The fiber dressing comprises a nanofiber membrane formed of aqueous polyurethane and a rigid polymer; wherein the hard segment / soft segment molar ratio (R value) in the aqueous polyurethane is 1.0~1.2; and the rigid polymer is one or more of polyvinyl butyral, polytetrafluoroethylene, polyvinyl chloride, and polystyrene. The soft segment of the waterborne polyurethane is one of polypropylene glycol, polyethylene glycol, polytetrahydrofuran glycol, polycaprolactone glycol, and polycarbonate glycol, and the hard segment is one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

2. The body temperature-induced heat-shrinkable fiber dressing as described in claim 1, characterized in that, The body temperature-induced heat-shrinkable nanofiber dressing has a thickness of 20–100 μm, a tensile strength of 5–30 MPa, an elongation at break of 50–400%, and a Young's modulus of 20–100 MPa.

3. The body temperature-induced heat-shrinkable fiber dressing as described in claim 1, characterized in that, The body temperature-induced heat-shrinkable fiber dressing shrinks by 10-80% when heated at 37°C for 30 min to 24 h; and in an in vitro rat wound closure experiment, the wound closure rate is 5-50% after heating at 37°C for 1 h to 12 h.

4. A method for preparing the body temperature-induced heat-shrinkable fiber dressing according to any one of claims 1-3, comprising: Aqueous polyurethane, rigid polymer, and solvent are mixed to obtain a spinning solution, which is then electrospun and dried to obtain a nanofiber membrane.

5. The preparation method according to claim 4, characterized in that, The rigid polymer is one or more of polyvinyl butyral, polytetrafluoroethylene, polyvinyl chloride, and polystyrene; the solvent is one or more of ethanol, hexafluoroisopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, acetone, and tetrahydrofuran.

6. The preparation method according to claim 4, characterized in that, The total concentration of waterborne polyurethane and rigid polymer in the spinning solution is 5-10 wt%; the mass ratio of waterborne polyurethane to rigid polymer is 8:2 to 2:

8.

7. The preparation method according to claim 4, characterized in that, The electrospinning process parameters are as follows: spinning voltage is 10-40kV, receiving distance is 10-20cm, injection speed is 1-5mL / h, temperature is 20-25℃, and relative humidity is 35-60%.

8. The preparation method according to claim 4, characterized in that, The drying time is 1 hour to 2 hours.

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