Electrically self-generating nanosilver PVDF composite fibers, preparation method therefor, and application

Abstract

Electrically self-generating nanosilver PVDF composite fibers, the composite fibers comprising polyvinylidene fluoride and nanosilver, the polyvinylidene fluoride and the nanosilver being combined by means of an electrospinning technique. AgNPs are introduced into a piezoelectric material PVDF, and micro-electric nanofibers are produced by means of an electrospinning technique, so that in addition to having nanosilver long-acting broad-spectrum antibacterial properties, the micro-electric nanofibers have the function of continuously generating a micro-current on a wound, without depending on external arrangements such as fixed power supplies or electrode sheets which are commonly used in current clinical practice and required for electrical stimulation. The present invention has important significance and effects in terms of reducing infection after burns / wounds, promoting wound healing, and ensuring patient safety and timely recovery, thereby solving the problem that PVDF nanocomposite films affect the recovery effects of wounds due to poor stability during use and limitations of use environments. Also provided are a preparation method for the electrically self-generating nanosilver PVDF composite fibers, and an application thereof in preparing a dressing for treating burns and wounds.

Description

A self-generating nano-silver PVDF composite fiber, its preparation method and application Technical Field

[0001] This invention relates to the fields of medical and biotechnology, and mainly to a self-generating nano-silver PVDF composite fiber and its preparation method and application, and a piezoelectric material-nano-silver composite fiber and its application. Background Technology

[0002] Human skin possesses a transskin potential of approximately 20–50 mV. When the skin is damaged and a wound forms, a persistent endogenous current, called the "injury current," is generated at the wound site, participating in the entire wound healing process. Studies have shown that applying appropriate voltage or current to the wound site at various stages of wound healing can effectively promote wound healing. Electrostimulation therapy has advantages such as being non-invasive, easy to operate, having a wide range of indications, and few complications.

[0003] Piezoelectric materials are crystalline materials that exhibit a voltage between their two ends when subjected to pressure, and are widely used in tissue engineering, biomedicine, and other fields. Polyvinylidene fluoride (PVDF) is a typical piezoelectric polymer. PVDF is typically fabricated into a nanocomposite membrane, consisting of an outer coating, a bactericidal layer, a gel layer, and a release liner from top to bottom. This nanocomposite membrane can generate ozone under near-infrared light excitation. In use, simply apply the product to the wound and irradiate it with near-infrared light to activate the bactericidal function of the nanocomposite membrane, achieving a sterile environment without the need for repeated bandaging. Simultaneously, the gel's sustained release at the wound site can directionally deliver growth factors to target cells, promote angiogenesis, assist in the differentiation of mesenchymal stem cells into exosomes, and provide continuous drug delivery, promoting wound healing. However, its use is limited by the reliance on near-infrared light, and the ozone-generating capacity of the nanocomposite membrane may be affected by environmental conditions, usage time and other factors, resulting in significant variations in the stability and durability of its bactericidal effect. In addition, the multi-layered structure makes it difficult to guarantee stability, which may affect the control of growth factors and bactericidal dosage during use, thus affecting the wound healing effect.

[0004] Because PVDF nanocomposite membranes have poor stability during use and are limited by the usage environment, they affect the wound healing effect. Summary of the Invention

[0005] This invention provides a self-generating nano-silver PVDF composite fiber, the composite fiber comprising polyvinylidene fluoride and nano-silver, wherein the polyvinylidene fluoride and the nano-silver are combined by electrospinning technology.

[0006] This invention, taking into account the current state of clinical development of PVDF piezoelectric materials, introduces AgNPs into PVDF piezoelectric materials and uses electrospinning technology to make the composite into filamentous nanofibers. The aim is to obtain a novel micro-electric nano-topical dressing that has antibacterial properties when used externally on wounds, while also having a continuous self-discharge function to promote wound healing. This improves the stability of the PVDF nanocomposite film and is not limited by the usage environment, providing a better treatment option for the clinical treatment of burns and trauma.

[0007] Preferably, the diameter of the composite fiber is 50-200 nm.

[0008] Preferably, the β phase content of the composite fiber is ≥80%.

[0009] Optionally, the mass ratio of the nano-silver to the polyvinylidene fluoride is 0.1 to 0.5:6.

[0010] Optionally, the mass ratio of the nano-silver to the polyvinylidene fluoride is 0.2:6.

[0011] Optionally, the mass ratio of the nano-silver to the polyvinylidene fluoride is 0.05 to 0.8:6.

[0012] This invention also provides a method for preparing self-generating nano-silver PVDF composite fibers, comprising the following steps:

[0013] S1: Mix polyvinylidene fluoride with an organic solvent to obtain the first spinning solution;

[0014] S2: Add nano-silver to the first spinning solution and mix to obtain the second spinning solution;

[0015] S3: Electrospin the second spinning solution to obtain the self-generating nano-silver PVDF composite fiber.

[0016] In one embodiment, the polyvinylidene fluoride has an average molecular weight Mw of 1,000,000 g / mol; N,N-dimethylformamide (DMF, ACS spectral grade, ≥99.8%); and nano-silver powder (AgNPs, ≥99.9%).

[0017] Optionally, the concentration of polyvinylidene fluoride in the first spinning solution is 12 wt%.

[0018] Optionally, the concentration of polyvinylidene fluoride in the first spinning solution is 10-14 wt%.

[0019] Optionally, the organic solvent is N,N-dimethylformamide.

[0020] Optionally, the PVDF powder is weighed using an electronic balance, and the DMF is measured and weighed using a graduated cylinder. In one exemplary embodiment, 12% by mass of polyvinylidene fluoride (PVDF) and dimethylformamide (DMF) are added to a beaker and stirred at a constant temperature (60°C) in a water bath with a magnetic stirrer until dissolved.

[0021] Optionally, in the second spinning solution, the mass ratio of the polyvinylidene fluoride to the nano-silver is 0.1 to 0.5:6.

[0022] Optionally, in the second spinning solution, the mass ratio of the polyvinylidene fluoride to the nano-silver is 0.05 to 0.8:6.

[0023] Optionally, in one exemplary embodiment, 1 mL of DMF is used to disperse the silver nanopowder, while still maintaining a PVDF / DMF ratio of 12 wt%. AgNPs are added to PVDF at a ratio of 0.2:6, and stirring is continued for 30 min to ensure thorough mixing.

[0024] Optionally, the parameters of the electrospinning include: solution feed rate of 0.4-0.7 ml / h, spinning temperature of 34.4-42.5℃, spinning relative humidity of 10-11%, receiving device rotation speed of 1400-1550 rpm, and receiving distance of 10-13 cm.

[0025] Optional parameters for electrospinning include: solution feed rate of 0.4–0.8 ml / h, spinning temperature of 31–35°C, spinning relative humidity of 10–15%, receiving device rotation speed of 1200–1800 rpm, and receiving distance of 10–15 cm.

[0026] Optionally, in an exemplary embodiment, the solution propulsion speed is 0.6 ml / h, the receiving device rotation speed is 1500 rpm, and the receiving distance is 12 cm.

[0027] Optionally, the parameters of the electrospinning include: positive voltage 18-22kV, negative voltage -1.5 to -2.5kV.

[0028] Optionally, the preparation method further includes: S3 further includes drying and sterilizing after electrospinning.

[0029] In one exemplary embodiment, a second spinning solution is pumped out using a needleless syringe to slowly draw it out, avoiding the generation of air bubbles, and excess second spinning solution is wiped off the syringe. Air bubbles are expelled from the syringe and tubing for stable electrospinning. The solution is pumped uniformly at a rate of 0.6 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, a voltage of +19.87 V and -1.93 kV is applied next to the metal tube. A grounded roller rotating at 1500 rpm is placed 12 cm from the needle, and the roller rotates at a uniform speed to collect PVDF / AgNPs piezoelectric nanofibers, obtaining the self-generating silver nanofiber PVDF composite fiber.

[0030] The present invention also provides the application of the above-mentioned composite fibers in the preparation of dressings for treating burns and trauma.

[0031] This invention also discloses a piezoelectric material-silver nanofiber composite, wherein the composite fiber comprises a piezoelectric polymer material and silver nanofiber, and the piezoelectric polymer material and the silver nanofiber are bonded together by electrospinning technology. In addition to PVDF, the piezoelectric polymer material can also be other types of piezoelectric polymer materials, or mixtures of different types of piezoelectric polymer materials.

[0032] The present invention also provides a medical product for use on mobile sites, the medical product comprising the above-mentioned piezoelectric material-nano-silver composite fiber, which can be applied, for example, to wounds, tendon anti-adhesion, bone or cartilage repair, etc., to promote wound healing in these highly mobile sites.

[0033] Compared with existing technologies, this invention provides a self-generating nano-silver PVDF composite fiber. The composite fiber comprises polyvinylidene fluoride (PVDF) and nano-silver, which are combined via electrospinning. This invention introduces AgNPs into the piezoelectric material PVDF and uses electrospinning to fabricate it into micro-electric nanofibers. This allows the fiber to possess the long-lasting, broad-spectrum antibacterial properties of nano-silver while continuously generating microcurrents on the wound surface, promoting wound healing. This discharge-driven healing function directly converts the mechanical energy of dressing deformation generated by local wound activity into electrical energy, without relying on external devices such as fixed power supplies and electrode pads commonly used in clinical electrical stimulation. This is of great significance and effectiveness in reducing post-burn / traumatic infection, promoting wound healing, ensuring patient safety, and facilitating timely recovery. The self-generating nano-silver PVDF composite fiber of this invention solves the problem of poor stability and environmental limitations of PVDF nanocomposite membranes, which negatively impact wound healing.

[0034] In the self-generating nano-silver PVDF composite fiber provided by this invention, PVDF, as a piezoelectric polymer, generates an electric field under mechanical deformations produced by the human body (such as those caused by joint movement), stimulating cell migration, proliferation, and collagen synthesis. After adding AgNPs to the composite fiber, the β-phase content of PVDF is significantly increased (β-phase content ≥80%, up to a maximum of 86.4%), thereby enhancing piezoelectric output. In the composite fiber of this invention, the formation and enhancement of the β-phase originate from the interaction between AgNPs and the PVDF molecular chains, promoting the formation of a polar crystalline phase.

[0035] In the preparation method of self-generating nano-silver PVDF composite fiber provided by the present invention, the high voltage (determined by both positive and negative voltages) and rapid stretching (generated by the selection of collector rotation speed) during the electrospinning process can further induce the formation of β phase, thereby enabling the fiber membrane to generate a sufficient electric field (output voltage up to 191.5mV, in a 0.2:6 ratio) under small deformation, promoting the activity of wound healing-related cells.

[0036] In the self-generating silver nanofiber PVDF composite fiber provided by this invention, AgNPs disrupt bacterial cell membranes and inhibit biofilm formation by releasing silver ions, exhibiting significant antibacterial effects against both Staphylococcus aureus and Escherichia coli. The preferred 0.2:6 mass ratio ensures stable release of silver ions, avoiding cytotoxicity caused by excessive release. Furthermore, the high specific surface area of ​​the nanofibers enhances the contact efficiency between AgNPs and bacteria, further improving the antibacterial performance.

[0037] The self-generating silver nanofiber PVDF composite fiber provided by this invention exhibits a synergistic effect of piezoelectric field and antibacterial function. Through electrical stimulation, it accelerates fibroblast migration and collagen deposition, while its antibacterial properties control local infection, creating a microenvironment conducive to healing. In vivo experiments have shown that this material can regulate the transformation of macrophages from pro-inflammatory M1 type to anti-inflammatory M2 type, reducing inflammatory responses and promoting tissue repair.

[0038] The present invention also provides a method for preparing self-generating nano-silver PVDF composite fibers, their application in the preparation of dressings for treating burns and wounds, as well as piezoelectric material-nano-silver composite fibers and medical products using them. Attached Figure Description

[0039] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 is a flowchart of a method for preparing self-generating nano-silver PVDF composite fibers according to an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of an exemplary electrostatic spinning machine according to the present invention.

[0042] Illustration:

[0043] Among them, 1-pump; 2-conduit; 3-needle; 4-drum; 5-voltage knob. Detailed Implementation

[0044] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application as detailed in the claims.

[0045] Piezoelectric materials are crystalline materials that exhibit a voltage between their two ends when subjected to pressure. The mechanism is as follows: piezoelectric crystals have low symmetry. When deformed by external force, the relative displacement of positive and negative ions in the unit cell causes the centers of positive and negative charges to no longer coincide, leading to macroscopic polarization of the crystal. Therefore, when a piezoelectric material deforms under pressure, opposite charges appear at its two ends. A typical piezoelectric polymer is stretched and polarized polyvinylidene fluoride (PVDF).

[0046] The C-F bonds in PVDF are highly polar, and two fluorine atoms are bonded to one carbon atom at the same time. This gives the PVDF monomer unit an extremely large dipole moment (5.8 × 10⁻³⁰ C·m), which has strong piezoelectric properties. It is widely used in fields such as the preparation of battery separators, piezoelectric membranes, filter membranes, sensors, electroacoustic transducers, tissue engineering, and biomedicine.

[0047] In the field of burns and wounds, silver nanoparticles (AgNPs) are widely used as an active ingredient in anti-infective materials due to their excellent antibacterial properties, and are applied to various burn and wound surfaces. Compared with traditional silver ions, silver nanoparticles have more durable antibacterial efficacy, broader and higher antibacterial activity, and fewer drug-resistant bacteria. They exhibit significant antibacterial efficacy against common drug-resistant bacteria in burn wounds, such as MRSA, Pseudomonas aeruginosa, Acinetobacter baumannii, and Candida albicans. Furthermore, AgNPs have lower cytotoxicity compared to silver ions.

[0048] Currently, there is limited research on PVDF for wound healing. The limited research mainly focuses on introducing different composites to alter the piezoelectric properties of PVDF. As an excellent piezoelectric material, PVDF also possesses good biocompatibility. By introducing different components to form composites, its piezoelectric properties and biocompatibility can be modified.

[0049] This invention provides a self-generating nano-silver PVDF composite fiber, the composite fiber comprising polyvinylidene fluoride and nano-silver, wherein the polyvinylidene fluoride and the nano-silver are combined by electrospinning technology, which can solve the problem that the poor stability of PVDF nanocomposite membranes during use and the limitation of the use environment affect the wound healing effect.

[0050] In this invention, the inventors, taking into account the current status of clinical development of PVDF piezoelectric materials, introduced AgNPs into PVDF piezoelectric materials and used electrospinning technology to make the composite into filamentous nanofibers. The aim is to obtain a novel micro-electric nano-topical dressing that has antibacterial properties when used externally on wounds, while also having a continuous self-discharge function to promote wound healing, thus providing a better treatment option for the clinical treatment of burns / trauma.

[0051] The bactericidal function of the self-generating nano-silver PVDF composite fiber provided in this invention embodiment does not depend on the irradiation of near-infrared light. When sufficient light is not available or the wound is in a position where light cannot be received, the effect is not limited. Moreover, because it is less affected by the environment, the bactericidal effect has good stability and durability.

[0052] Preferably, the diameter of the composite fiber is 50-200 nm.

[0053] Preferably, the β phase content of the composite fiber is ≥80%.

[0054] In some embodiments, the mass ratio of the nano-silver to the polyvinylidene fluoride is 0.1 to 0.5:6.

[0055] In some embodiments, the mass ratio of the nanosilver to the polyvinylidene fluoride is 0.2:6.

[0056] In some embodiments, the mass ratio of the nano-silver to the polyvinylidene fluoride is 0.05 to 0.8:6.

[0057] This invention also provides a method for preparing self-generating nano-silver PVDF composite fibers, comprising the following steps:

[0058] S1: Mix polyvinylidene fluoride with an organic solvent to obtain the first spinning solution;

[0059] S2: Add nano-silver to the first spinning solution and mix to obtain the second spinning solution;

[0060] S3: Electrospin the second spinning solution to obtain the self-generating nano-silver PVDF composite fiber.

[0061] In some embodiments, Figure 1 shows a flowchart of a method for preparing self-generating nano-silver PVDF composite fibers, wherein the organic solvent is N,N-dimethylformamide.

[0062] In some embodiments, the average molecular weight Mw of polyvinylidene fluoride is 1,000,000 g / mol; N,N-dimethylformamide (DMF, ACS spectral grade, ≥99.8%); and nano silver powder (AgNPs, ≥99.9%).

[0063] In some embodiments, the concentration of polyvinylidene fluoride in the first spinning solution is 12 wt%.

[0064] In some embodiments, the concentration of polyvinylidene fluoride in the first spinning solution is 10-14 wt%.

[0065] In some embodiments, the organic solvent is N,N-dimethylformamide.

[0066] In some embodiments, as shown in Figure 1, PVDF powder is weighed using an electronic balance, and DMF is measured and weighed using a graduated cylinder. 12% by mass of polyvinylidene fluoride (PVDF) and dimethylformamide (DMF) are added to a beaker and stirred in a water bath with a magnetic stirrer at a constant temperature (60°C, 200 rpm) until dissolved.

[0067] In some embodiments, in the second spinning solution, the mass ratio of polyvinylidene fluoride to nanosilver is 0.1 to 0.5:6.

[0068] In some embodiments, the mass ratio of polyvinylidene fluoride to nanosilver in the second spinning solution is 0.05 to 0.8:6.

[0069] In some embodiments, 1 mL of DMF is used to dissolve the nano-silver powder while maintaining the PVDF / DMF ratio at 12 wt%. AgNPs are added to the PVDF at a ratio of 0.2:6, and stirring is continued for 30 min to ensure thorough mixing.

[0070] In some embodiments, the parameters of the electrospinning include: a solution feed rate of 0.4–0.7 ml / h, a spinning temperature of 34.4–42.5 °C, a spinning relative humidity of 10–11%, a receiving device rotation speed of 1400–1550 rpm, and a receiving distance of 10–13 cm.

[0071] Optional parameters for electrospinning include: solution feed rate of 0.4–0.8 ml / h, spinning temperature of 31–35°C, spinning relative humidity of 10–15%, receiving device rotation speed of 1200–1800 rpm, and receiving distance of 10–15 cm.

[0072] Optionally, the solution propulsion speed is 0.6 ml / h, the receiving device rotation speed is 1500 rpm, and the receiving distance is 12 cm.

[0073] Optionally, the parameters of the electrospinning include: positive voltage 18-22kV, negative voltage -1.5 to -2.5kV.

[0074] Optionally, the preparation method further includes: S3 further includes drying and sterilizing after electrospinning.

[0075] In some embodiments, as shown in Figure 2, a schematic diagram of an electrospinning machine, the second spinning solution is loaded into pump 1. The second spinning solution is slowly drawn out using a needleless syringe to avoid generating air bubbles, and excess second spinning solution is wiped off the syringe. Air bubbles are expelled from the syringe and conduit 2 to stabilize electrospinning. The solution is pumped uniformly at a rate of 0.6 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, the voltage knob 5 is rotated to set the voltage applied next to the metal tube to +19.87V and -1.93kV, with needle 3 as the positive electrode and drum 4 as the negative electrode. A grounded roller rotating at 1500 rpm is placed 12 cm away from the needle, rotating at a uniform speed to collect PVDF / AgNPs piezoelectric nanofibers, thus obtaining the self-generating nanosilver PVDF composite fiber.

[0076] This application also provides the use of the above-mentioned composite fibers in the preparation of dressings for treating burns and trauma.

[0077] Besides choosing polyvinylidene fluoride (PVDF) as a piezoelectric polymer material as the matrix material, those skilled in the art can foresee the use of other piezoelectric polymer materials as matrix materials, as well as the piezoelectric material-silver nanofibers produced therefrom, and the use of medical products made from the piezoelectric material-silver nanofibers in injury repair, such as for wound healing, tendon adhesion prevention, promoting healing and adhesion prevention after arterial anastomosis, promoting healing and adhesion prevention after intestinal anastomosis, bone or cartilage repair, etc., to promote wound healing in these highly mobile areas.

[0078] Exemplary experimental operations of the present invention include:

[0079] 1. Solution preparation and electrospinning stage

[0080] Raw material preparation: Prepare PVDF / DMF solution and AgNPs suspension according to the ratio, mix and stir to form a uniform electrospinning precursor solution.

[0081] Electrospinning: The precursor liquid is spun into nanofibers using electrospinning equipment. The electric field strength and collector rotation speed are optimized to ensure that the fiber diameter distribution is between 50-200nm and the fiber structure is uniform without bead-like defects.

[0082] 2. Fiber curing and treatment stage

[0083] After the fiber membrane is dried, performance tests are conducted, including scanning electron microscopy (SEM) to observe fiber morphology, Fourier transform infrared spectroscopy (ATR-FTIR) to analyze β phase content, X-ray diffraction (XRD) to confirm crystal phase structure, and differential scanning calorimetry (DSC) to evaluate thermal stability.

[0084] 3. Functional verification phase

[0085] The antibacterial properties (against Escherichia coli and Staphylococcus aureus) and biocompatibility (human skin fibroblast proliferation assay) of the fibrous membrane were verified through in vitro experiments, and the wound healing effect was confirmed through in vivo experiments.

[0086] In step 1, an exemplary method for preparing a self-generating nano-silver PVDF composite fiber is as follows:

[0087] 1.1 Raw material preparation

[0088] Polyvinylidene fluoride (PVDF, with a suitable molecular weight) was selected as the matrix material and dissolved in N,N-dimethylformamide (DMF, with a purity ≥99.8%) to prepare a PVDF solution with a mass concentration of 10-14 wt%. A concentration of 12 wt% was preferred to ensure solution viscosity and electrospinning stability.

[0089] Silver nanoparticles (AgNPs, purity ≥99.99%, particle size 9-24 nm) were dispersed in DMF to prepare an AgNPs suspension. AgNPs were then added to the PVDF solution at a mass ratio of 0.05:6 to 0.8:6 (preferably 0.2:6) and magnetically stirred at 50-70°C until uniformly mixed, avoiding bubble formation.

[0090] 1.2 Electrospinning process

[0091] Fiber preparation is performed using electrospinning equipment. Electrospinning parameters include: a distance of 10-15 cm (preferably 12 cm) between the spinning needle and the collector; a positive voltage of 18-22 kV (preferably 19.87 kV); a negative voltage of -1.5 to -2.5 kV (preferably -1.93 kV); a solution flow rate of 0.4-0.8 mL / h (preferably 0.6 mL / h); and a collector rotation speed of 1200-1800 rpm (preferably 1500 rpm).

[0092] Electrospinning is performed in an environment with a temperature of 31-35℃ and a humidity of 10-15%, or a temperature of 34.4-42.5℃ and a humidity of 10-11%, to ensure uniform fiber morphology. The equipment is preheated for 2 hours before electrospinning to stabilize system operation. An 18-gauge needle is used as the spinning nozzle, and a soft-faced roller is used to collect uniform PVDF-AgNPs nanofibers.

[0093] 1.3 Post-processing

[0094] The resulting nanofiber membranes were dried at room temperature to remove residual solvent. The membrane thickness was controlled between 50 and 200 μm to ensure flexibility and piezoelectric properties. The membranes were then sterilized using ultraviolet light to ensure biocompatibility.

[0095] The following provides several specific experiments and related test results.

[0096] Example 1:

[0097] PVDF powder was weighed using an electronic balance, and DMF was measured and weighed using a graduated cylinder. PVDF and DMF at a mass fraction of 12% were added to a beaker and stirred in a water bath with a magnetic stirrer at a constant temperature (60℃, 200 rpm) until dissolved, obtaining the first spinning solution. Nano-silver powder was dispersed using 1 mL of DMF, maintaining a PVDF / DMF ratio of 12 wt%. AgNPs were added to the PVDF at a ratio of 0.2:6, and stirring was continued for 30 min to ensure thorough mixing, obtaining the second spinning solution.

[0098] The second spinning solution was pumped out using a needleless syringe to slowly draw it out, avoiding the generation of air bubbles. Excess solution was wiped off the syringe. Air bubbles were expelled from the syringe and tubing to stabilize electrospinning. The solution was pumped uniformly at a rate of 0.6 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, a voltage of +19.87 V and -1.93 kV was applied near the metal tube. The spinning temperature was 34.4 °C, and the relative humidity was 10%. A grounded roller rotating at 1500 rpm was placed 12 cm away from the needle. The roller was rotated at a uniform speed to collect PVDF / AgNPs piezoelectric nanofibers. The fibers were dried at room temperature for 24 hours and then sterilized under UV light for 30 minutes to obtain the first self-generating silver nanofiber PVDF composite fiber.

[0099] Performance test results: The fiber diameter ranges from 50 to 200 nm. During electrospinning, PVDF spontaneously forms a β phase, which dominates the fiber composition. Upon addition of AgNPs, the diffraction peaks of the β phase in the PVDF fiber are significantly enhanced, indicating that the introduction of AgNPs promotes the formation and stabilization of the β phase in PVDF. This phenomenon suggests that AgNPs not only do not disrupt the crystal structure of PVDF but also contribute to the ordered arrangement of PVDF crystals, thereby increasing the proportion of the β phase. The melting point of the fiber remains relatively stable at approximately 160 °C, with minimal change in enthalpy of fusion.

[0100] Example 2:

[0101] PVDF powder was weighed using an electronic balance, and DMF was measured and weighed using a graduated cylinder. PVDF and DMF at a mass fraction of 12% were added to a beaker and stirred in a water bath with a magnetic stirrer at a constant temperature (60℃, 200 rpm) until dissolved, obtaining the first spinning solution. Nano-silver powder was dispersed using 1 mL of DMF, maintaining a PVDF / DMF ratio of 12 wt%. AgNPs were added to the PVDF at a ratio of 0.1:6, and stirring was continued for 30 min to ensure thorough mixing, obtaining the second spinning solution.

[0102] The second spinning solution was pumped out using a needleless syringe to slowly draw it out, avoiding the generation of air bubbles. Excess solution was wiped off the syringe. Air bubbles were expelled from the syringe and tubing to stabilize the electrospinning process. The solution was pumped uniformly at a rate of 0.4 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, a voltage of +19.87 V and -1.93 kV was applied near the metal tube. The spinning temperature was 42.5 °C, and the relative humidity was 11%. A grounded roller rotating at 1400 rpm was placed 13 cm away from the needle. The roller was rotated at a uniform speed to collect the PVDF / AgNPs piezoelectric nanofibers. The fibers were dried at room temperature for 24 hours and then sterilized under UV light for 30 minutes to obtain the second self-generating silver nanofiber PVDF composite fiber.

[0103] Performance test results: The fiber diameter ranges from 50 to 200 nm. During electrospinning, PVDF spontaneously forms a β phase, which dominates the fiber composition. Upon addition of AgNPs, the diffraction peaks of the β phase in the PVDF fiber are significantly enhanced, indicating that the introduction of AgNPs promotes the formation and stabilization of the β phase in PVDF. This phenomenon suggests that AgNPs not only do not disrupt the crystal structure of PVDF but also contribute to the ordered arrangement of PVDF crystals, thereby increasing the proportion of the β phase. The melting point of the fiber remains relatively stable at approximately 160 °C, with minimal change in enthalpy of fusion.

[0104] Example 3:

[0105] PVDF powder was weighed using an electronic balance, and DMF was measured and weighed using a graduated cylinder. PVDF and DMF at a mass fraction of 12% were added to a beaker and stirred in a water bath with a magnetic stirrer at a constant temperature (60℃, 200 rpm) until dissolved, obtaining the first spinning solution. Nano-silver powder was dispersed using 1 mL of DMF, maintaining a PVDF / DMF ratio of 12 wt%. AgNPs were added to the PVDF at a ratio of 0.5:6, and stirring was continued for 30 min to ensure thorough mixing, obtaining the second spinning solution.

[0106] The second spinning solution was pumped out using a needleless syringe to slowly draw it out, avoiding the generation of air bubbles. Excess solution was wiped off the syringe. Air bubbles were expelled from the syringe and tubing to stabilize the electrospinning process. The solution was pumped uniformly at a rate of 0.7 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, a voltage of +19.87 V and -1.93 kV was applied near the metal tube. The spinning temperature was 40.5 °C, and the relative humidity was 11%. A grounded roller rotating at 1550 rpm was placed 10 cm away from the needle. The roller was rotated at a uniform speed to collect the PVDF / AgNPs piezoelectric nanofibers. The fibers were dried at room temperature for 24 hours and then sterilized under UV light for 30 minutes to obtain the third self-generating silver nanofiber PVDF composite fiber.

[0107] Performance test results: The fiber diameter ranges from 50 to 200 nm. During electrospinning, PVDF spontaneously forms a β phase, which dominates the fiber composition. Upon addition of AgNPs, the diffraction peaks of the β phase in the PVDF fiber are significantly enhanced, indicating that the introduction of AgNPs promotes the formation and stabilization of the β phase in PVDF. This phenomenon suggests that AgNPs not only do not disrupt the crystal structure of PVDF but also contribute to the ordered arrangement of PVDF crystals, thereby increasing the proportion of the β phase. The melting point of the fiber remains relatively stable at approximately 160 °C, with minimal change in enthalpy of fusion.

[0108] Example 4:

[0109] PVDF powder was weighed using an electronic balance, and DMF was measured and weighed using a graduated cylinder. PVDF and DMF at a mass fraction of 12% were added to a beaker and stirred in a water bath with a magnetic stirrer at a constant temperature (60℃, 200 rpm) until dissolved, obtaining the first spinning solution. Nano-silver powder was dispersed using 1 mL of DMF, maintaining a PVDF / DMF ratio of 12 wt%. AgNPs were added to the PVDF at a ratio of 0.2:3, and stirring was continued for 30 min to ensure thorough mixing, obtaining the second spinning solution.

[0110] The second spinning solution was pumped out using a needleless syringe to slowly draw it out, avoiding the generation of air bubbles. Excess solution was wiped off the syringe. Air bubbles were expelled from the syringe and tubing to stabilize the electrospinning process. The solution was pumped uniformly at a rate of 0.5 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, a voltage of +19.87 V and -1.93 kV was applied near the metal tube. The spinning temperature was 41.5 °C, and the relative humidity was 11%. A grounded roller rotating at 1450 rpm was placed 11 cm away from the needle. The PVDF / AgNPs piezoelectric nanofibers were collected by uniform rotation, dried at room temperature for 24 hours, and then sterilized under UV light for 30 minutes to obtain the fourth self-generating silver nanofiber PVDF composite fiber.

[0111] Performance test results: The fiber diameter ranges from 50 to 200 nm. During electrospinning, PVDF spontaneously forms a β phase, which dominates the fiber composition. Upon addition of AgNPs, the diffraction peaks of the β phase in the PVDF fiber are significantly enhanced, indicating that the introduction of AgNPs promotes the formation and stabilization of the β phase in PVDF. This phenomenon suggests that AgNPs not only do not disrupt the crystal structure of PVDF but also contribute to the ordered arrangement of PVDF crystals, thereby increasing the proportion of the β phase. The melting point of the fiber remains relatively stable at approximately 160 °C, with minimal change in enthalpy of fusion.

[0112] Example 5:

[0113] PVDF powder was weighed using an electronic balance, and DMF was measured and weighed using a graduated cylinder. PVDF and DMF at a mass fraction of 12% were added to a beaker and stirred in a water bath with a magnetic stirrer at a constant temperature (60℃, 200 rpm) until dissolved, obtaining the first spinning solution. Nano-silver powder was dispersed using 1 mL of DMF, maintaining a PVDF / DMF ratio of 12 wt%. AgNPs were added to the PVDF at a ratio of 0.3:6, and stirring was continued for 30 min to ensure thorough mixing, obtaining the second spinning solution.

[0114] The second spinning solution was pumped out using a needleless syringe to slowly draw it out, avoiding the generation of air bubbles. Excess solution was wiped off the syringe. Air bubbles were expelled from the syringe and tubing to stabilize the electrospinning process. The solution was pumped uniformly at a rate of 0.4 ml / h from an 18-gauge syringe needle (tip diameter approximately 1.27 mm) fixed to the positive electrode as a spinneret. For safety, a voltage of +19.87 V and -1.93 kV was applied near the metal tube. The spinning temperature was 34.4 °C, and the relative humidity was 11%. A grounded roller rotating at 1500 rpm was placed 12 cm away from the needle. The roller was rotated at a uniform speed to collect the PVDF / AgNPs piezoelectric nanofibers. The fibers were dried at room temperature for 24 hours and then sterilized under UV light for 30 minutes to obtain the fifth self-generating silver nanofiber PVDF composite fiber.

[0115] Performance test results: The fiber diameter ranges from 50 to 200 nm. During electrospinning, PVDF spontaneously forms a β phase, which dominates the fiber composition. Upon addition of AgNPs, the diffraction peaks of the β phase in the PVDF fiber are significantly enhanced, indicating that the introduction of AgNPs promotes the formation and stabilization of the β phase in PVDF. This phenomenon suggests that AgNPs not only do not disrupt the crystal structure of PVDF but also contribute to the ordered arrangement of PVDF crystals, thereby increasing the proportion of the β phase. The melting point of the fiber remains relatively stable at approximately 160 °C, with minimal change in enthalpy of fusion.

[0116] Example 6

[0117] Prepare according to the following steps:

[0118] 1. Dissolve 12g of PVDF powder in 100mL of DMF and stir at 60℃ until completely dissolved to prepare a 12wt% solution.

[0119] 2. Disperse 0.4 g of AgNPs in 1 mL of DMF, add PVDF solution, and stir until homogeneous (AgNPs / PVDF mass ratio is 0.2:6).

[0120] 3. Load the mixed solution into the electrospinning equipment and set the spinning parameters as follows: distance between needle and collector 12cm, positive voltage 19.87kV, negative voltage -1.93kV, flow rate 0.6mL / h, collector rotation speed 1500rpm, ambient temperature 32℃, humidity 12%.

[0121] 4. Electrospin for 4 hours, collect the fiber membrane, dry at room temperature for 24 hours, and sterilize under ultraviolet light for 30 minutes to obtain the sixth self-generating nano-silver PVDF composite fiber.

[0122] Performance test results: The fiber diameter distribution is 50-200 nm, the β phase content is 86.4%, the melting point of the fiber remains at approximately 160℃, and the enthalpy of melting does not change significantly.

[0123] Example 7 (Functional Verification):

[0124] In vitro experiments

[0125] The general testing methods for antibacterial rate (Staphylococcus aureus) and cell viability (HDF) are as follows.

[0126] Culture Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and methicillin-resistant Staphylococcus aureus (MRSA) to the logarithmic growth phase, and standardize the bacterial concentration to 10⁻⁶. 5 CFU / mL. PVDF-AgNPs piezoelectric nanofibers were placed in sterile medium containing 60 μg / mL silver ions and incubated at 37°C with constant temperature and shaking. Equal volumes of *S. aureus*, *E. coli*, and MRSA bacterial suspensions were added to test tubes containing PVDF-AgNPs piezoelectric nanofibers with different Ag / PVDF mass ratios. Control groups included pure PVDF material and untreated bacterial suspensions. At set time points (0 h, 2 h, 4 h, 12 h), 3 mL samples were collected and replaced with fresh medium to maintain constant volume and stirring conditions. Antimicrobial activity was tested using two methods: agar plate method – using methicillin-resistant *Staphylococcus aureus* (MRSA) as the target bacterium, MRSA colonies were gently collected using an inoculation loop and incubated in a shaker. Twelve hours later, 5 μL of culture medium was extracted from each test tube, and colony forming units (CFU) were assessed using the spread plate method. Bacterial concentration determination: The antibacterial stability of the five materials was assessed by placing them in sterile culture medium (10 mL, 36°C). At set time intervals, 3 mL samples were extracted and replaced while maintaining agitation. For the antibacterial experiment, solutions of *Escherichia coli* and *Staphylococcus aureus* (10 mL) were prepared. 5 (1 cell), and five different material masses were added according to the silver ion concentration, with a control group included. Samples were extracted at 0, 3, 6, 9, and 12 hours, and bacterial morphology was observed after 12 hours using SEM / TEM-EDS.

[0127] Human dermal fibroblasts (HDF) were purchased from the American Type Culture Collection (ATCC), with passage numbers controlled between P5 and P6. Cells were cultured in Dulbecco's Modified Eagle Medium (DMEM) containing 10% fetal bovine serum (FBS) and 1% penicillin / streptomycin at 37°C in a 5% CO2 incubator until 80-90% cell adhesion was achieved. PVDF-AgNPs piezoelectric nanofibers were added to the cell culture medium at a ratio of 1 g / 10 mL, and the mixture was incubated at 37°C with shaking for 24 hours. The cells were then aseptically processed using a 0.22 μm filter. HDF cells were cultured at a rate of 5 × 10⁶ cells / mL. 3 Cells were seeded at a density of [number] cells / well in 96-well plates and cultured at 37°C with 5% CO2 until complete cell adhesion (approximately 24 hours). After cell adhesion, material extraction solution was added to each well, while the control group received an equal volume of pure culture medium. Cells were cultured for 24 and 48 hours. After each culture, 10 μL of CCK-8 reagent was added to each well, gently shaken to mix, and incubated at 37°C for 2 hours. The absorbance (OD value) of each well was measured at 450 nm using a microplate reader. The cell proliferation rate was calculated using the following formula: Cell proliferation rate (%) = ((Experimental group OD value - Background OD value) / (Control group OD value - Background OD value)) × 100%. Wherein, OD value refers to optical density, background OD value is the background value under cell-free conditions, and the experimental group OD value and control group OD value are the absorbance of the experimental and control groups at specific time points, respectively. The cell biocompatibility of PVDF-AgNPs piezoelectric nanofibers was evaluated by analyzing the effects of different extract concentrations and culture times (0 h, 4 h, 16 h, 24 h) on HDF (human skin fibroblast) cell viability. This process involved using cell proliferation assays to determine the material's effect on cell growth and viability.

[0128] The experimental results of Examples 1-6 are as follows:

[0129] The first self-generating nano-silver PVDF composite fiber of Example 1 has an antibacterial rate (Staphylococcus aureus) >99% and a cell survival rate (HDF) >95%.

[0130] The second self-generating nano-silver PVDF composite fiber of Example 2 has an antibacterial rate (Staphylococcus aureus) >90% and a cell survival rate (HDF) >95%.

[0131] The third self-generating nano-silver PVDF composite fiber of Example 3 has an antibacterial rate (Staphylococcus aureus) >90% and a cell survival rate (HDF) >95%.

[0132] Example 4 shows that the fourth self-generating nano-silver PVDF composite fiber has an antibacterial rate (Staphylococcus aureus) >90% and a cell survival rate (HDF) >95%.

[0133] The fifth self-generating nano-silver PVDF composite fiber of Example 5 has an antibacterial rate (Staphylococcus aureus) >90% and a cell survival rate (HDF) >95%.

[0134] The sixth self-generating nano-silver PVDF composite fiber of Example 6 has an antibacterial rate (Staphylococcus aureus) >99% and a cell viability (HDF) >95%.

[0135] In vivo experiments: Animal in vivo experiments to observe the effect of self-generated nano-silver PVDF composite fibers as a functional wound dressing to accelerate wound healing.

[0136] (1) The first, second, third, fourth, fifth, and sixth self-generating nano-silver PVDF composite fibers prepared in Examples 1 to 6 were soaked in 70% ethanol solution for 10 minutes, and then soaked in physiological saline for 30 minutes to achieve disinfection and thorough removal of any residual solvent components in the self-generating nano-silver PVDF composite fibers. They were then used to prepare dressings for treating burns and wounds, resulting in the first, second, third, fourth, fifth, and sixth self-generating nano-silver PVDF composite fiber dressings.

[0137] (2) The above-mentioned power-generating nano-silver PVDF composite fiber dressing was used to repair the skin wounds on the back of SD rats (a circular full-thickness skin with a diameter of 1 cm was removed), and the wound healing was continuously observed.

[0138] Compared to traditional gauze dressings, wounds treated with the dressings of Examples 1-6 of this invention largely healed by day 17, requiring dressing changes every two days during treatment. Wounds treated with traditional gauze dressings, however, only largely healed by day 25, requiring dressing changes every other day during treatment. Furthermore, the functional wound dressings of Examples 1-6 of this invention exhibit less adhesion to the wound surface, resulting in less bleeding during dressing changes, while traditional gauze dressings often adhere to the wound surface and cause bleeding.

[0139] Therefore, it can be seen that the self-generating nano-silver PVDF composite fiber provided by the present invention has the effect of accelerating wound healing as a functional wound dressing.

[0140] Meanwhile, mice using the first self-generating nano-silver PVDF composite fiber dressing of Example 1 showed the fastest recovery and the best wound condition.

[0141] This invention provides a self-generating nano-silver PVDF composite fiber, comprising polyvinylidene fluoride (PVDF) and nano-silver, which are combined via electrospinning. AgNPs are introduced into the piezoelectric material PVDF and fabricated into micro-electric nanofibers using electrospinning technology. This allows the fiber to possess the long-lasting, broad-spectrum antibacterial properties of nano-silver while continuously generating microcurrents on the wound surface, promoting wound healing. This discharge-driven healing function directly converts the mechanical energy of dressing deformation generated by local wound activity into electrical energy, without relying on external devices such as fixed power supplies and electrode pads commonly required for clinical electrical stimulation. This is of great significance and effectiveness in reducing post-burn / traumatic infection, promoting wound healing, ensuring patient safety, and facilitating timely recovery. It also solves the problem of poor stability and environmental limitations of PVDF nanocomposite membranes, which negatively impact wound healing.

[0142] The present invention also provides a method for preparing self-generating nano-silver PVDF composite fibers, and their application in the preparation of dressings for treating burns and wounds.

[0143] Besides choosing polyvinylidene fluoride (PVDF) as a piezoelectric polymer material as the matrix material, those skilled in the art can also foresee the use of other piezoelectric polymer materials as matrix materials based on the above embodiments, as well as the use of piezoelectric materials-nano-silver composite fibers made therefrom, and medical products made from the piezoelectric materials-nano-silver composite fibers in injury repair, such as for wounds, tendon anti-adhesion, bone or cartilage repair, etc., to promote wound healing in these highly mobile areas.

[0144] Similar parts between the embodiments provided in this invention can be referred to mutually. The specific embodiments provided above are merely examples under the overall concept of this application and do not constitute a limitation on the scope of protection of this invention. For those skilled in the art, any other embodiments extended from the solution of this invention without creative effort are within the scope of protection of this invention.

Claims

1. A self-generating nano-silver PVDF composite fiber, characterized in that, The composite fiber comprises polyvinylidene fluoride and silver nanoparticles, wherein the polyvinylidene fluoride and the silver nanoparticles are combined by electrospinning technology.

2. The composite fiber according to claim 1, characterized in that, The diameter of the composite fiber is 50-200 nm.

3. The composite fiber according to claim 1, characterized in that, The β phase content of the composite fiber is ≥80%.

4. The composite fiber according to claim 1, characterized in that, The mass ratio of the nano-silver to the polyvinylidene fluoride is 0.1 to 0.5:

6.

5. The composite fiber according to claim 4, characterized in that, The mass ratio of the nano-silver to the polyvinylidene fluoride is 0.2:

6.

6. The composite fiber according to claim 1, characterized in that, The mass ratio of the nano-silver to the polyvinylidene fluoride is 0.05 to 0.8:

6.

7. A method for preparing the composite fiber according to claim 1, characterized in that, Includes the following steps: S1: Mix polyvinylidene fluoride with an organic solvent to obtain the first spinning solution; S2: Add nano-silver to the first spinning solution and mix to obtain the second spinning solution; S3: Electrospin the second spinning solution to obtain the self-generating nano-silver PVDF composite fiber.

8. The preparation method according to claim 7, characterized in that, The concentration of polyvinylidene fluoride in the first spinning solution is 12 wt%.

9. The preparation method according to claim 7, characterized in that, The concentration of polyvinylidene fluoride in the first spinning solution is 10-14 wt%.

10. The preparation method according to claim 7, characterized in that, The organic solvent is N,N-dimethylformamide.

11. The preparation method according to claim 7, characterized in that, In the second spinning solution, the mass ratio of polyvinylidene fluoride to nano-silver is 0.1 to 0.5:

6.

12. The preparation method according to claim 7, characterized in that, In the second spinning solution, the mass ratio of polyvinylidene fluoride to nano-silver is 0.05 to 0.8:

6.

13. The preparation method according to claim 7, characterized in that, The parameters of the electrospinning include: The solution propulsion speed is 0.4–0.7 ml / h, the spinning temperature is 34.4–42.5℃, the spinning relative humidity is 10–11%, the receiving device rotation speed is 1400–1550 rpm, and the receiving distance is 10–13 cm.

14. The preparation method according to claim 7, characterized in that, The parameters of the electrospinning include: The solution propulsion speed is 0.4–0.8 ml / h, the spinning temperature is 31–35℃, the spinning relative humidity is 10–15%, the receiving device rotation speed is 1200–1800 rpm, and the receiving distance is 10–15 cm.

15. The preparation method according to claim 7, characterized in that, The solution propulsion speed is 0.6 ml / h, the receiving device rotation speed is 1500 rpm, and the receiving distance is 12 cm.

16. The preparation method according to claim 14, characterized in that, The parameters for electrospinning include: positive voltage 18-22kV and negative voltage -1.5 to -2.5kV.

17. The preparation method according to claim 7, characterized in that, Also includes: S3 also includes drying and sterilization after electrospinning.

18. The use of the composite fiber according to any one of claims 1 to 6 in the preparation of dressings for treating burns and wounds.

19. A piezoelectric material-silver nanofiber composite, characterized in that, The composite fiber comprises a piezoelectric polymer material and silver nanoparticles, wherein the piezoelectric polymer material and the silver nanoparticles are combined by electrospinning technology.

20. A medical product for use on active sites, characterized in that, Includes the piezoelectric material-silver nanofiber as described in claim 19.

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