Thermosensitive material, temperature-responsive nanofiber membrane, preparation method and application

Abstract

This invention discloses a thermosensitive material, a temperature-responsive nanofiber membrane, a preparation method, and applications. The thermosensitive material of this invention is shown in formula (Ⅰ). The thermosensitive material of this invention has a wide phase transition temperature, broadening its application range. The temperature-responsive nanofiber membrane of this invention possesses antibacterial, hemostatic, scar repair, and temperature-responsive contraction functions. It can exert an antibacterial effect in the early stage of wound healing and significantly help wound contraction, rapidly transitioning to the wound repair stage. During the scar formation stage, it reduces collagen deposition, ultimately forming a fully closed and mature scar-free healing zone.

Description

Technical Field

[0001] This invention belongs to the field of medical antibacterial materials, and relates to a temperature-sensitive material, a temperature-responsive nanofiber membrane, its preparation method, and its application. Background Art

[0002] Temperature-sensitive materials are generally macromolecules, mainly composed of a macromolecular backbone, hydrophilic groups, and hydrophobic groups. Under temperature stimulation, the hydrogen bonding forces between this material and water molecules change, resulting in a phase transition. The macroscopic manifestation of this transition is either from hydrophilic to hydrophobic or vice versa.

[0003] Common dressings adhere directly to wounds to accelerate wound healing by providing a moist and breathable environment that isolates bacteria and promotes granulation and epithelial growth. Among the many techniques for preparing wound dressings, electrospinning is an important method due to its advantages such as large specific surface area and high porosity, which provide physical isolation from bacteria and allow for breathability. Summary of the Invention

[0004] Purpose of the invention: In order to solve the above-mentioned technical problems, the present invention provides a temperature-sensitive material, a temperature-responsive nanofiber membrane, a preparation method and an application.

[0005] Technical solution: The temperature-sensitive material of the present invention has the structural formula shown in formula (Ⅰ):

[0006]

[0007] Where x = 100, y = 17-20, z = 3-8.

[0008] In some embodiments, x = 100, y = 17, z = 8.

[0009] The phase transition temperature of the thermosensitive material described above in this invention is 32.5–42.5°C. The minimum critical dissolution temperature is 36.1°C.

[0010] The method for preparing the thermosensitive material described above in this invention includes the following steps:

[0011] N-Isopropylacrylamide (NIPAM), N-hydroxymethylacrylamide (NMA), and octadecyl acrylate (SA) were added to tetrahydrofuran, and azobisisobutyronitrile (ANOVA) was added under nitrogen purging. The mixture was then refluxed under a nitrogen atmosphere for 24–48 h. The resulting product was purified to obtain a poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide-co-octadecyl acrylate) (PNNS) terpolymer with NIPAM, NMA, and SA as comonomers.

[0012] In some embodiments, the purification includes the following steps: adding ice-cold n-hexane to the reaction system after the reaction is completed to precipitate the precipitate, then filtering and drying the precipitate to obtain PNNS polymer.

[0013] In some embodiments, the icy n-hexane precipitation step can be repeated 2 to 3 times.

[0014] In some embodiments, the molar ratio of N-isopropylacrylamide, N-hydroxymethylacrylamide, and octadecyl acrylate is 100:(15-20):(2-10).

[0015] In some embodiments, the molar ratio of N-isopropylacrylamide, N-hydroxymethylacrylamide, and octadecyl acrylate is 100:20:3.

[0016] The temperature-responsive nanofiber membrane of the present invention includes the above-mentioned temperature-sensitive material.

[0017] Since electrospun fiber membranes alone, such as polycaprolactone fiber membranes, do not perform optimally, in some embodiments, this application incorporates quaternized silicone with antibacterial properties and PNNS with temperature sensitivity into the electrospun membrane. The resulting dressing exhibits better antibacterial and antifouling effects and ensures minimal scarring in the later stages of wound healing, resulting in better healing outcomes than ordinary dressings. This not only minimizes the risk of infection but also helps prevent bacterial infection in patients, thereby promoting faster wound healing.

[0018] In some embodiments, the quaternized silicone of the present invention is a long-chain alkyl-substituted quaternized silicone QP12 prepared under patent number 2020108463079.

[0019] In some embodiments, the temperature-responsive nanofiber membrane of the present invention comprises polycaprolactone, quaternized silicone, and a thermosensitive material in a mass ratio of (3-7):(1-3):(1-10).

[0020] The temperature-responsive nanofiber membrane prepared by this invention has an antibacterial effect in the early stage of wound healing and significantly helps wound contraction, rapidly transitioning to the wound repair stage. During the scar formation stage, it reduces collagen deposition and finally forms a fully closed and mature scar-free healing area.

[0021] The method for preparing the temperature-responsive nanofiber membrane of the present invention includes the following steps:

[0022] Polycaprolactone, quaternized silicone, and a thermosensitive material were dissolved in hexafluoroisopropanol to prepare a spinning solution with a mass-volume percentage concentration of 6–20%. Electrospinning was carried out under the following conditions: voltage of 19–25 kV, spinning solution flow rate of 1.2–2.0 mL / h, temperature of 20–25 °C, air humidity of 35–40%, and distance between the needle and the receiving aluminum foil of 15–20 cm, to obtain a temperature-responsive nanofiber membrane.

[0023] In some embodiments, the method for preparing the temperature-responsive nanofiber membrane includes the following steps:

[0024] Polycaprolactone and quaternized silicone were weighed in a mass ratio of 70:30 and dissolved in hexafluoroisopropanol to prepare an MQP spinning solution with a mass-volume percentage concentration of 6-10%. Thermosensitive material PNNS with a mass concentration of 1-5% was added to the MQP spinning solution. The solution was stirred and dissolved at room temperature, and then degassed by ultrasonication to obtain a homogeneous spinning solution. Electrospinning was carried out using a 10mL syringe with a metal conductive needle with an inner diameter of 0.60mm (20G) under the conditions of a voltage of 19kV, a spinning solution flow rate of 1.2mL / h, a temperature of 20℃, an air humidity of 35%, and a distance of 15cm between the needle and the receiving aluminum foil. The solution was then vacuum dried at room temperature for 24h to remove residual solvent, resulting in a temperature-responsive nanofiber membrane.

[0025] In some embodiments, the mass ratio of polycaprolactone, quaternized silicone and thermosensitive material in the temperature-responsive nanofiber membrane is (3-7):(1-3):(1-10).

[0026] The application of the thermosensitive material described in this invention, or the thermosensitive material prepared by the preparation method described herein, or the temperature-responsive nanofiber membrane prepared by the preparation method described herein, as a wound dressing in wound healing.

[0027] Beneficial Effects: The thermosensitive material of this invention has a wide phase transition temperature, broadening its application range. The temperature-responsive nanofiber membrane of this invention uses quaternized silicone (QP12), thermosensitive material (PNNS), and polycaprolactone (PCL) as a dressing, possessing antibacterial, hemostatic, scar repair, and temperature-responsive shrinkage functions. It can exert an antibacterial effect in the early stages of wound healing and significantly help wound contraction, rapidly transitioning to the wound repair phase. During the scar formation phase, it reduces collagen deposition, ultimately forming a fully closed and mature scar-free healing zone. Attached Figure Description

[0028] Figure 1 A schematic diagram illustrating wound healing using thermosensitive dressings;

[0029] Figure 2 For PNNS polymer 1HNMR spectrum;

[0030] Figure 3 The relationship between transmittance and temperature at 500 nm for a 0.5 wt% PNNS aqueous solution;

[0031] Figure 4 The infrared spectrum of NQP;

[0032] Figure 5 The results show the thermal response of the nanofiber membrane at 38℃.

[0033] Figure 6 The results show the thermal response of the nanofiber membrane at 40℃.

[0034] Figure 7 The results are the tensile properties of the nanofiber membrane.

[0035] Figure 8 These are the results of the hydrophilicity test of the nanofiber membrane;

[0036] Figure 9 The results of the cytotoxicity test for the nanofiber membrane;

[0037] Figure 10 Results of bacterial invasion experiments on nanofiber membranes;

[0038] Figure 11 These are the results of an experiment on the wound healing properties of nanofiber membranes;

[0039] Figure 12 A statistical graph showing the experimental results of wound healing properties of nanofiber membranes;

[0040] Figure 13 The graph shows the effect of the wound healing test on the body weight of mice.

[0041] Figure 14 This is a graph showing the wound healing rate results within 14 days post-surgery.

[0042] Figure 15 H&E and MASSON staining of wound tissue sections from mice on day 14 is shown in the figure.

[0043] Figure 16 The results are for CD31 immunofluorescence. Detailed Implementation

[0044] Example 1: Synthesis of Thermosensitive Material (PNNS)

[0045] Accurately weigh 9.05 g NIPAM, 1.62 g NMA, and 0.81 g SA (comonomer molar ratio (NIPAM:NMA:SA = 100:20:3)) and add them to a 100 mL three-necked flask. Then add 20 mL tetrahydrofuran. Fix the flask in an oil bath and install a reflux condenser. Stir under nitrogen purging for 20 min, then add 10 mg AIBN. Continue stirring under nitrogen purging for another 20 min to completely remove oxygen. Raise the temperature to 65 °C and then react at this temperature for 24 h. The synthesized polymer semi-solid... The bulk solution was transferred to a 250 mL beaker, and tetrahydrofuran was added to about 50 mL to the mark. After heating to dissolve, about 150 mL of ice-cold n-hexane was used to precipitate the product, followed by filtration. The filtered product was dissolved in tetrahydrofuran and precipitated again with n-hexane. The filtered product was then vacuum dried at room temperature for 72 h to obtain the purified PNNS polymer. This yielded a poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide-co-octadecyl acrylate) terpolymer synthesized with NIPAM, NMA, and SA as comonomers.

[0046] Figure 2 For PNNS polymer 1 HNMR spectrum. The assignments of the spectral peaks can be seen in the figure. Figure 1 According to the standard, the peak shifts are in the order f>c>g>d>h>b>a>i>e>j. Hf, influenced by the electron-withdrawing effects of the carbonyl and hydroxyl groups, shifts to a lower field, with a chemical shift of 8.03. Hc is mainly affected by the electron-withdrawing effect of the carbonyl group, with a chemical shift of 7.21. Hg, influenced by the electronegativity of O and N atoms, has a lower electron cloud density, resulting in a chemical shift of 4.50. Hd, influenced by the electronegativity of N and the electron-donating effect of the methyl group, has a chemical shift of 3.84. The hydrogen atoms on the original carbon-carbon double bond, due to the electron-withdrawing effect of the carbonyl group, had shifts between 5.6 and 6.3. However, due to the polymerization and bond breakage to form single bonds, there is no hydrogen signal from the carbon-carbon double bond in this region, causing the original positive and negative shielding regions of the carbon-carbon double bond to disappear. The carbon and hydrogen atoms are no longer affected by the negative shielding effect, causing the hydrogen nucleus vibration peak at this location to shift towards a higher magnetic field, thus reducing the chemical shift value. Ha is more affected by the electron-withdrawing effect of the carbonyl group than Hb, hence Ha has a chemical shift of 1.97, and Hb has a chemical shift of 1.53. Hi represents the long-chain hydrogen of CH2, with a chemical shift of 1.23. He represents the isopropyl methyl hydrogen, with a chemical shift of 1.04. Hj represents the terminal methyl hydrogen of the long carbon chain, with a chemical shift of 0.85. Hh represents the active hydrogen, located around 3.5. Based on the integrated areas of peaks c, f, and j in the spectrum, the molar ratio of the three monomers NIPAM, NMA, and SA in PNNS is calculated to be 100:17:8.

[0047] Figure 3The curves showing the relationship between transmittance and temperature at a wavelength of 500 nm for a PNNS aqueous solution with a mass concentration of approximately 0.5% are presented. It can be seen that when the temperature is below 32.5℃, the transmittance of the PNNS aqueous solution is close to 100%, and the solution is completely transparent. This is because, at this temperature, the hydrophilic PNNS is completely dissolved in water, and the molecular chains are in an extended state. When the solution temperature exceeds 32.5℃, the transmittance gradually decreases until it approaches 0 at approximately 45℃. This is because PNNS changes from hydrophilic to hydrophobic, undergoing phase separation, and correspondingly, the molecular chains change from an extended state to a coiled state, forming spherical polymer particles that scatter visible light. This result indicates that the phase transition temperature range of PNNS is 32.5–42.5℃, which is wider than that of PNIPAM homopolymers because of the introduction of non-temperature-responsive NMA and SA units into the polymer molecular chains. The temperature corresponding to 50% transmittance is 36.1℃, which is the lowest critical dissolution temperature (LCST) of PNNS.

[0048] Example 2: Preparation of Thermosensitive Nanofiber Membrane (NQP)

[0049] Polycaprolactone (PCL) and quaternized silicone (QP12) in a mass ratio of 70:30 were dissolved in hexafluoroisopropanol (HFIP) to prepare an MQP spinning solution with a mass-volume percentage of 6%. The above steps were repeated, and then the content of PNNS was gradually increased in 1% increments until the maximum spinning solution concentration reached 10%, preparing a series of NQP spinning solutions of various concentrations (see Table 1). The solutions were then dissolved at room temperature with magnetic stirring and degassed by ultrasonication to obtain homogeneous MQP and NQP spinning solutions. Electrospinning was performed using a 10 mL syringe with a 0.60 mm (20 G) inner diameter metal conductive needle under the following conditions: voltage 19 kV, spinning solution flow rate 1.2 mL / h, 20 °C, air humidity 35%, and a distance of 15 cm between the needle and the receiving aluminum foil. Vacuum drying was then performed at room temperature for 24 h to remove residual solvent, yielding a temperature-responsive nanofiber membrane.

[0050] Table 1. Spinning solution formulation and preparation parameters

[0051]

[0052] Figure 4 This is the infrared spectrum of NQP, which contains all the stretching vibration peaks of QP12, such as at 3300 cm⁻¹. -1 The hydroxyl vibration peak is around 2900 cm⁻¹. -1 2800cm -1 The dodecyl vibration peak is around 1050 cm⁻¹. -1 The Si-O-Si stretching vibration peak nearby; 1728 cm⁻¹ in the PCL film-1 1296cm -1 1239cm -1 The stretching vibration peaks of the C=O, C=C, and CO bonds at the three locations also correspond to signals in the MQP. Additionally, PNNS shows a signal at 1641 cm⁻¹ in the membrane. -1 The amide I band (carbonyl stretching peak) at 1539 cm⁻¹ -1 The absorption peak of the amide II band (NH bending vibration peak) at the α-terminus also has a corresponding signal in the spectra of both. These results indicate that the various components coexist in the material in a physically mixed form.

[0053] Example 3: Performance Test Results

[0054] (1) Thermal responsiveness analysis of thermosensitive nanofiber membranes (NQP)

[0055] Nanofiber membranes were immersed in water, and the membrane area was measured at two temperature points: 38℃ and 40℃. The relationship between membrane area shrinkage and temperature was obtained. The results are as follows: Figure 5 and Figure 6 As shown, all fiber membranes exhibit varying degrees of area reduction. The MQP fiber membrane, prepared without the addition of thermosensitive materials, exhibits the lowest thermosensitivity, with an area shrinkage rate not exceeding 5% when the temperature reaches 40°C. The addition of the thermosensitive material PNNS endows the fiber membrane with temperature-responsive functionality. Among them, fiber NQP-2 demonstrates a response speed distinct from other fiber membranes, with an area shrinkage reaching 13%. The reason may be that when the added thermosensitive material is of this mass, its composition exhibits more uniform mixing with other substances. PNNS material exhibits the characteristic of being hard at low temperatures and soft at high temperatures during the synthesis stage, a property that is perfectly suited to this application. The high crystallinity and low melting point of polycaprolactone (PCL) cause it to gradually soften under temperature influence, resulting in significant extensibility. Pure PCL membrane fibers are insufficient to produce the elastic deformation after fiber stretching. With the addition of thermosensitive material, the fibers repel internal moisture, and the gaps between atoms in the fiber skeleton increase, leading to not only macroscopic shrinkage between fibers but also polymerization between internal molecules. Furthermore, the addition of the material optimizes the balance between the fiber stiffness of PCL and the softness of quaternized silicone, causing the mechanical properties to continuously change with temperature, gradually transforming from hard fibers to soft fibers, with the fastest trigger temperature response. The experimental results show that the PNNS-modified thermosensitive nanofiber membrane (NQP-2) in this application exhibits excellent shrinkage characteristics, which is more conducive to wound closure.

[0056] (2) Mechanical property analysis

[0057] Figure 7 The tensile properties test results of the nanofiber membrane are provided by... Figure 7As shown in Table 2, compared to the fibrous membrane MQP12, the addition of thermosensitive materials has a significant impact on the elongation at break of MQP. NQP-2 exhibits tensile properties different from other membranes, with the tensile strength increasing to a maximum of 16.24±1.23 MPa and the elongation at break also rising to a maximum of 68.89±3.24%, resulting in an overall improvement in mechanical strength and toughness. The mechanical strength of the wound dressing ensures stability in practical applications and provides a favorable biomechanical environment before new tissue formation.

[0058] Table 2. Mechanical test results of nanofiber membranes

[0059]

[0060] (3) Water contact angle test

[0061] To ensure timely treatment of wound exudate and maintain suitable ambient humidity for wound healing, the hydrophilicity of the fiber membrane should be tested during the initial selection process. The hydrophilicity / hydrophobicity of fiber dressings is closely related to wound healing. Figure 8 The figure shows the water contact angle test results for the nanofiber membranes. As can be seen, with the increasing content of the thermosensitive material, the differences in performance between nanofiber membranes NQP-1 and NQP-3 are not significant. When the PNNS content exceeds 3%, the nanofiber membrane exhibits significant hydrophobicity, and the hydrophilicity of the membrane gradually decreases. This may be because a large amount of thermosensitive material covers the fiber surface, exhibiting active hydrophobicity; on the other hand, the fiber porosity is significantly reduced, resulting in stronger water-blocking performance.

[0062] (4) Biocompatibility-cytotoxicity test of nanofiber membrane

[0063] This experiment investigated the proliferation of L929 cells in different nanofiber membrane extracts. Cell counts after 24 hours of culture were measured using the CCK-8 assay to assess the ability of different nanofiber membranes to promote L929 cell proliferation. Cytotoxicity tests were also conducted on the three nanofiber membrane extracts. Figure 9 As shown, 0.6% phenol was used as a positive control, and the cells showed no activity. The PCL extract of the fiber membrane showed no cytotoxicity at any concentration, and the cell survival rate was over 100%. However, the performance of MQP and NQP-2 materials was not very promising. Normal cell viability could only be guaranteed when the dilution concentration reached 12.5%, possibly because quaternized silicone has cytotoxic ability.

[0064] (5) Bacterial invasiveness test

[0065] Figure 10The results of the bacterial invasion test on the nanofiber membrane are shown. After sterilization, the nanofiber membrane was tested against Staphylococcus aureus. After co-culturing for 8 hours, electron microscopy images after fixation and dehydration revealed that bacteria were densely packed on the surface of the PCL fiber membrane and embedded in the interstices of the fibers. In contrast, the surfaces of the antibacterial fiber membranes MQP and NQP-2 showed virtually no bacterial adhesion. This indicates that the quaternized silicone has excellent antibacterial properties and indirectly shows that the introduction of temperature-sensitive materials did not affect its antibacterial properties.

[0066] (6) Wound healing test

[0067] Generally, the 7th day after surgery is the main period of skin healing and repair, and by the 14th day, the wound is basically healed and enters the mature stage. A wound healing test was conducted using mice in a blank gauze group and a commercially available product group as controls. On the first day of the experiment, randomly assigned mice were given a 10mm diameter wound, and the test samples at the wound site were changed regularly. The experimental results are as follows: Figure 11 As shown and Figure 12 As shown, the experimental results indicated that mice in the blank gauze group and the commercially available product group developed suppuration 3 days post-surgery, while the MQP group and the NQP-2 group showed clean wound surfaces without bacterial infection, and the wounds in the NQP-2 group significantly shrank. This was attributed to the antibacterial effect of the antibacterial material QP12, and the temperature-sensitive material in NQP-2 causing overall contraction of the fibrous membrane due to temperature stimulation. These antibacterial dressings, MQP and NQP-2, help the body destroy bacteria and remove necrotic tissue, laying the foundation for tissue regeneration and repair. On day 7, the wounds in each group showed varying degrees of shrinkage. The wounds in the blank gauze group and the commercially available product group still had blood clots, indicating a state of inflammatory repair. The MQP group had already formed dry scabs, while the NQP-2 group had semi-moist scabs, showing more significant healing. This may be because the fibrous membrane more effectively prevents moisture evaporation from the skin surface, allowing the wound to heal towards a moist state. On day 10, the wounds in all groups further shrank, but... Figure 11 The wounds in the blank, commercially available, and MQP groups, as shown, were not yet closed and showed signs of local scab formation, which is caused by local fibrous tissue hyperplasia. In contrast, the NQP-2 group had completed granulation tissue filling and covering the wound without scab formation, indicating that fibrous tissue had not excessively proliferated. On day 14, the wounds in the NQP-2 group were basically closed, with a color consistent with normal skin, and no raised scar formation. The wounds in other groups healed more slowly; the blank and commercially available groups showed raised scars and significant pigmentation. This was due to early inflammatory cytokine stimulation and scar fibrous tissue hyperplasia. The healing level of the MQP group was equivalent to that of the NQP-2 group on day 10, with no raised scars and minimal pigmentation. Figure 12Based on the changes in wound contour within the first 14 days in each group, it was clearly observed that MQP and NQP-2 had better wound healing promotion performance, with the NQP-2 group showing a more significant improvement. These results indicate that NQP-2 is significantly superior to this commercially available product in terms of wound healing and scar repair. Furthermore, a comparison of the wound healing processes of MQP and NQP-2 shows that timely prevention of wound infection and induction of closure after wound formation can help the wound transition to the repair phase or even the maturation phase more quickly. This also indirectly demonstrates that the addition of thermosensitive materials does not hinder the efficacy of the original antibacterial scar repair materials and can even work synergistically.

[0068] (7) Changes in mouse body weight

[0069] Seven days after mice adapted to their environment, a wound model was created under anesthesia. Body weight changes were observed and recorded on days 3, 7, 10, and 14. The results are as follows: Figure 13 As shown, by Figure 13 It was observed that the mice experienced significant weight loss due to skin removal on their backs or decreased appetite afterward. However, by day 7, their weight gradually returned to near its original level, and they showed slow weight gain over the following week. This is an important indicator of wound healing in mice.

[0070] (8) Wound healing rate

[0071] Analysis of wound healing rate within 14 days post-surgery, as follows: Figure 14 As shown. At 3 days, breathable dressings can meet the needs of wound exchange of substances with the external environment, achieving the goal of shrinking the wound edges, such as gauze and breathable dressings (Tegader). TM The wound healing rates of the MQP group, NQP-2 group, and gauze group were 14.30±8.97%, 25.27±4.38%, and 29.35±5.22%, respectively. The healing rate of NQP-2 was particularly high at 41.91±6.08%, showing a significant difference compared to the gauze group (p<0.05). After 7 days, the healing rates of all groups increased, and the differences between groups were similar to those on day 3. In the control group, due to the breathable material Tegaderm... TM The thin and soft nature of the NQP-2 dressing makes it easy to remove, unlike gauze which tends to adhere to tissues and hinder healing. It exhibited a higher healing rate than gauze (44.24±3.35%). There was no significant difference in healing between the MQP and NQP-2 groups, possibly because granulation tissue had largely covered the wound, and collagen deposition was the primary process, making both NQP-2 and NQP-2 superior to the two control dressings in wound healing. After 14 days, the healing rate of NQP-2 was 96.12±1.34%, significantly different from the gauze group (p<0.0001) and slightly higher than the MQP group (90.79±2.05%). Wound closure rates in the control groups were all less than 90%. These results indicate that the thermosensitive dressing NQP-2 can significantly accelerate wound healing.

[0072] (9) Immunohistochemistry

[0073] 1) H&E and Masson staining: HE and MASSON staining of pathological tissue sections from mouse wounds on day 14 is shown in the figure. Figure 15 As shown, the degree of epithelialization and granulation tissue formation in the wound can be observed, and collagen deposition in the granulation tissue can be observed. On day 14, increased squamous epithelium and epidermal thickness were observed in all wound tissues; the gauze group still showed a small number of infiltrated inflammatory cells; Tegaderm... TM The epidermis of the control group was uneven with raised scar tissue. The granulation tissue in the MQP group was slightly thinner, while the granulation tissue in the NQP-2 group was thicker and smoother, with no scar hyperplasia. This is largely consistent with the image information in the wound healing diagram, indicating that the NQP-2 group had the best wound healing effect. Fewer new hair follicles appeared in the newly formed tissue, and both control groups showed varying degrees of scar hyperplasia; the smoothness of the epidermal layer in the NQP-2 group was higher than that in the MQP group. These results indicate that NQP-2 can rapidly achieve epithelialization within two weeks and effectively inhibit scar hyperplasia while promoting healing. At 14 days post-surgery, collagen deposition increased in the control group, while collagen was relatively reduced and more oriented in the MQP and NQP-2 groups. This may be due to the remodeling of granulation tissue at the wound site after most of the wound has healed. In the control group, collagen distribution was disordered and there was scar hyperplasia on the skin surface; the amount of collagen deposition in the MQP and NQP-2 groups tended to be normal. The NQP-2 group showed more orderly and neat collagen arrangement and was more consistent with the morphology and orientation of substances in normal skin, demonstrating the scar repair effect of quaternized silicone.

[0074] 2) CD31 immunofluorescence:

[0075] Platelet-endothelial cell adhesion molecule (CD31) is a membrane glycoprotein. Belonging to the immunoglobulin superfamily, it is expressed on the cell membranes of all continuous endothelial cells, but not on discontinuous sinusoidal endothelial cells. It is also expressed on megakaryocytes, platelets, and some T and B cells. In vascular endothelial cells, it is expressed in tubular forms, and the amount of expression reflects the degree of angiogenesis. In the early stages of healing, the earlier the angiogenesis occurs, the better the healing efficiency; in the later stages of healing, the number of vessels supplying nutrients decreases, which is beneficial for epidermal remodeling and skin surface smoothing, reducing scar formation. Its expression results are shown in […]. Figure 16 On day 7, the gauze group and Tegaderm TMThe NQP-2 group had fewer blood vessels than the other groups and a slower rate of blood vessel regeneration. By day 14, the number of blood vessels in the gauze had increased relatively, and the wound was not completely closed. By day 7, due to good wound management, granulation tissue grew well, and both the NQP-2 and MQP groups showed abundant capillary expression. As time progressed, by day 14, the granulation tissue gradually matured, some capillary lumens became occluded, their number decreased, and a few vessels remodeled into arterioles and venules. The NQP-2 group showed more pronounced results, suggesting that it could further accelerate wound healing.

Claims

1. A temperature-responsive nanofiber membrane, characterized in that, The temperature-responsive nanofiber membrane was prepared by the following method: Polycaprolactone and quaternized silicone with a mass percentage of 70:30 were dissolved in hexafluoroisopropanol, and an MQP spinning solution with a mass-volume percentage concentration of 6-10% was prepared. A thermosensitive material with a mass concentration of 2% was added to the MQP spinning solution, stirred and dissolved at room temperature, and ultrasonically degassed to obtain a homogeneous spinning solution. A 10 mL syringe with a metal conductive needle with an inner diameter of 0.60 mm was used for electrospinning under the conditions of a voltage of 19 kV, a spinning solution flow rate of 1.2 mL / h, a temperature of 20℃, an air humidity of 35%, and a distance of 15 cm between the needle and the receiving aluminum foil. The solution was then vacuum dried at room temperature for 24 h to remove residual solvent, thus obtaining the temperature-responsive nanofiber membrane. The structural formula of the temperature-sensitive material is shown in formula (Ⅰ): （Ⅰ） Where x=100, y=17~20, z=3~8.

2. The temperature-responsive nanofiber membrane according to claim 1, characterized in that, The phase transition temperature of the thermosensitive material is 32.5~42.5℃.

3. The temperature-responsive nanofiber membrane according to claim 1, characterized in that, The temperature-sensitive material is prepared by the following method: N-Isopropylacrylamide, N-hydroxymethylacrylamide, and octadecyl acrylate were added to tetrahydrofuran, and azobisisobutyronitrile was added under nitrogen atmosphere. The mixture was refluxed under nitrogen atmosphere for 24-48 h. The resulting product was purified to obtain the thermosensitive material PNNS polymer. The molar ratio of N-isopropylacrylamide, N-hydroxymethylacrylamide, and octadecyl acrylate was 100:(15-20):(2-10).

4. A method for preparing a temperature-responsive nanofiber membrane as described in claim 1, characterized in that, The following steps are involved: Polycaprolactone and quaternized silicone were weighed in a mass ratio of 70:30 and dissolved in hexafluoroisopropanol to prepare an MQP spinning solution with a mass-volume percentage concentration of 6-10%. A thermosensitive material with a mass concentration of 2% was added to the MQP spinning solution. The solution was stirred and dissolved at room temperature, and then degassed by ultrasonication to obtain a homogeneous spinning solution. Electrospinning was carried out using a 10 mL syringe with a metal conductive needle with an inner diameter of 0.60 mm under the following conditions: voltage of 19 kV, spinning solution flow rate of 1.2 mL / h, temperature of 20℃, air humidity of 35%, and distance between the needle and the receiving aluminum foil of 15 cm. The solution was then vacuum dried at room temperature for 24 h to remove residual solvent, resulting in a temperature-responsive nanofiber membrane.

5. The application of a temperature-responsive nanofiber membrane as described in any one of claims 1 to 3 or a temperature-responsive nanofiber membrane prepared by the preparation method as described in claim 4 in the preparation of wound dressings.

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