Preparation method and application of piezoelectric enhanced antibacterial composite nano dressing

Abstract

The present invention belongs to the field of nano dressing technology, and specifically relates to the preparation and application of a piezoelectric enhanced antibacterial composite nano dressing. 3‑x / ZnFe2O4 nanocomposite materials, and then polyvinylidene fluoride fiber membrane was prepared by SBS method; finally, MZ was dispersed in PVDF spinning solution and co-spinned to prepare PVDF@MoO 3‑x By constructing a Z-type heterojunction MZ nanocomposite, the electron-hole recombination efficiency is reduced, the ability to generate ROS is enhanced, and the photocatalytic ability of the P@MZ nanocomposite fiber dressing is improved. Furthermore, the localized thermal effect enhances peroxidase (POD) activity, thereby promoting the generation of hydroxyl radicals (·OH). Heat increases CAT activity, prompting more oxygen to participate in the photocatalytic reaction, thereby effectively improving photocatalytic performance and achieving better antibacterial efficacy for the P@MZ nanocomposite fiber dressing. This effectively enhances photocatalytic activity and significantly inactivates drug-resistant bacteria in wounds.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano-dressings, and in particular relates to a preparation method and application of a piezoelectrically enhanced antibacterial composite nano-dressing. Background Art

[0002] Chronic diabetic wounds are one of the complications of diabetes. Difficulty in wound healing is one of the characteristics of chronic diabetic wounds, which has become a health issue of increasing concern worldwide. Wound healing is divided into four chronological stages: hemostasis, inflammation, proliferation, and remodeling. Diabetic wounds are affected by bacterial infection, abnormal angiogenesis, tissue hypoxia, etc., which affect the wound healing process and can lead to incomplete or delayed wound healing. Treatment methods such as surgical debridement and antibiotics are ineffective. In recent years, wound dressings have gradually become a research hotspot for the treatment of chronic diabetic wounds, including nanofiber membranes, hydrogels, microneedle patches, etc. Among them, nanofiber membranes have a greater clinical translation background due to their good biocompatibility and processing properties.

[0003] There are many types of nanofiber membranes, including polyester lactone (PCL), thermoplastic polyurethane (TPU), polyacrylonitrile (PAN), and polylactic acid (PLA). These fibers typically lack antibacterial and bactericidal properties, and they are often co-spun with antimicrobial nanomaterials and drugs to achieve antimicrobial efficacy. As a scaffold, nanofibers can isolate wounds from the surrounding microenvironment. The antimicrobial properties of the nanomaterials within them kill bacteria infecting the wound, thereby achieving an antibacterial and wound-healing effect. Among the many fiber substrates, PVDF has garnered widespread attention from researchers due to its unique properties. As a piezoelectric material, PVDF depolarizes when subjected to external mechanical forces, generating an endogenous electric field. This transfer and migration of electrons produces highly cytotoxic reactive oxygen species (ROS), which inactivate bacteria. Therefore, PVDF is an ideal wound dressing material.

[0004] With the rapid development of precision medicine, an increasing number of advanced therapeutic technologies have been widely adopted in clinical practice. Among the numerous therapeutic approaches, phototherapy is considered one of the most promising strategies for treating microbial infections due to its controllable properties, low toxicity and side effects, spatiotemporal selectivity, non-invasiveness, broad antimicrobial spectrum, and resistance to drug resistance. Phototherapy includes photodynamic therapy (PDT) and photothermal therapy (PTT). PDT relies on the generation of ROS by photosensitizers under certain wavelengths to exert its antimicrobial effect, but its effectiveness is often limited by the laser's penetration depth. PTT, on the other hand, is not affected by penetration depth, and the combination of the two can achieve synergistic antimicrobial effects. ROS and thermal energy can irreversibly damage the bases of bacterial DNA, disrupting its double-stranded structure, interfering with normal bacterial proliferation and metabolism, and causing DNA damage, effectively killing a variety of pathogens, including Gram-positive and Gram-negative bacteria, fungi, viruses, and parasites. In addition to phototherapy, chemodynamic therapy (CDT) is also an effective microbial inactivation strategy. Since its discovery in 2016, CDT has been widely used in the treatment of wound infections. However, photothermal therapy requires high temperatures to completely kill bacteria, which can damage healthy tissue near the infected area. Low temperatures cannot completely kill bacteria. The introduction of CDT will complement PTT's antibacterial properties, enhancing the antibacterial effect of low-temperature PTT. In summary, the construction of a synergistic antibacterial system combining CDT, PDT, and PTT will exert excellent antibacterial effects and meet the treatment needs of diseases such as bacterial infections. To this end, the present invention proposes the preparation and application of a piezoelectrically enhanced antibacterial composite nano-dressing. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of a piezoelectric enhanced antibacterial composite nano dressing. An MZ nanocomposite material is proposed for the first time. By constructing a Z-type heterojunction, the recombination efficiency of electrons and holes is reduced, and the photocatalytic performance of the material is improved. The present invention prepares a P@MZ fiber dressing for the first time. By doping the MZ nanocomposite material, the β phase of PVDF is increased, the piezoelectric performance of the P@MZ fiber dressing is enhanced, and the antibacterial performance of the P@MZ fiber dressing is improved.

[0006] The technical solutions adopted by the present invention are as follows:

[0007] Step 1: Molybdenum metal powder was dispersed in ethanol solution and stirred at room temperature, and then H2O2 was added to obtain a yellow solution. The solution was then transferred to a polytetrafluoroethylene container, sealed in a stainless steel autoclave, and reacted at 160 ° C for 12 h. After cooling to room temperature, it was washed with ethanol and water three times respectively, and dried in vacuum at 60 ° C overnight to obtain MoO 3-x (M) powder;

[0008] Step 2: Disperse zinc chloride, ferric chloride hexahydrate, sodium citrate dihydrate, and sodium acetate in ethylene glycol in sequence and dissolve them by ultrasonication to obtain a reddish-brown mixed solution. The solution is then transferred to a polytetrafluoroethylene container and reacted at 200°C for 12 hours. After cooling to room temperature, the solution is washed with ethanol and water three times, respectively, and dried at 60°C for 12 hours to obtain ZnFe2O4 (Z) powder.

[0009] Step 3: Mo metal powder was dispersed in ethanol solution and stirred at room temperature, and H2O2 was added to obtain a yellow solution. Z powder was then dispersed in the yellow solution, ultrasonically dispersed, and transferred to a polytetrafluoroethylene container. The container was sealed in a stainless steel autoclave and reacted at 160 ° C for 12 h. After cooling to room temperature, the container was washed with ethanol and water three times respectively, and dried in vacuum at 60 ° C overnight to obtain MoO 3-x / ZnFe2O4 (MZ) nanocomposites;

[0010] Step 4: Dissolve the MZ nanomaterial in DMF, ultrasonicate for 30 min, then add PVDF powder, and magnetically stir at 42 °C for 12 h to prepare a PVDF spinning solution with uniform MZ dispersion; finally, the obtained spinning solution is subjected to solution jet spinning technology to obtain PVDF@MoO 3-x / ZnFe2O4 (P@MZ) composite nanofiber membrane.

[0011] Preferably, the concentration of the H2O2 solution used in step 1 and step 3 is 30%; in step 4, the specific parameters of the solution jet spinning technology are: needle specification: 23 G, propulsion rate: 10 mL / h, receiving roller speed: 500 rpm, receiving distance: 30 cm, and wind pressure: 120 MPa.

[0012] The invention discloses an application of a piezoelectrically enhanced antibacterial composite nano-dressing in the preparation of a dressing drug for treating external wounds of diabetic patients.

[0013] The technical effects achieved by the present invention are:

[0014] The present invention proposes an MZ nanocomposite material for the first time, which reduces the recombination efficiency of electrons and holes and improves the photocatalytic performance of the material by constructing a Z-type heterojunction; the present invention prepares a P@MZ fiber dressing for the first time, which improves the β phase of PVDF by doping with the MZ nanocomposite material, enhances the piezoelectric performance of the P@MZ fiber dressing, and improves the antibacterial performance of the P@MZ fiber dressing.

[0015] The present invention designs and develops a piezoelectrically enhanced and photocatalytic nanocomposite fiber dressing for antibacterial treatment. The present invention uses PVDF as the base material and incorporates MoO 3-x / ZnFe2O4 (MZ) nanocomposite materials were prepared, and then PVDF fiber membrane was prepared by SBS method; finally, MZ was dispersed in PVDF spinning solution and co-spinned to prepare PVDF@MoO 3-x / ZnFe2O4 (P@MZ) nanofiber dressing. The construction of a Z-type heterojunction MZ nanocomposite reduces the recombination efficiency of electrons and holes, enhances the generation of ROS, and improves the photocatalytic capacity of the P@MZ nanocomposite fiber dressing. Furthermore, the localized thermal effect enhances POD activity, thereby promoting the generation of •OH. Simultaneously, the heat increases CAT activity, encouraging more oxygen to participate in the photocatalytic reaction, effectively improving the photocatalytic performance and resulting in enhanced antibacterial efficacy of the P@MZ nanocomposite fiber dressing. Furthermore, loading the nanocomposite (MZ) significantly enhances the piezoelectricity of PVDF. Under ultrasound, free charges within the built-in electric field of PVDF are transferred to the heterojunction interface, participating in the transport of photogenerated electrons and holes, effectively enhancing photocatalytic activity and significantly inactivating drug-resistant bacteria in wounds. In summary, the P@MZ nanocomposite fiber dressing achieves antibacterial effects from multiple perspectives, significantly enhancing the antibacterial efficacy of diabetic wounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1a SEM images of M nanomaterials;

[0017] Figure 1b XRD patterns of M nanomaterials;

[0018] Figure 2a SEM images of Z nanomaterials;

[0019] Figure 2b XRD patterns of Z nanomaterials;

[0020] Figure 3a SEM images of MZ nanocomposites;

[0021] Figure 3b Elemental mapping of MZ nanocomposites;

[0022] Figure 3c XRD patterns of MZ nanocomposites;

[0023] Figure 3d PL spectra of MZ nanocomposites;

[0024] Figure 3e MZ is generated in darkness and light respectively 1 ESR spectra of O2 and •OH;

[0025] Figure 3f The band structure of MZ nanocomposites;

[0026] Figure 3g UV absorption spectra of TMB color development reaction catalyzed by MZ under different material concentrations, temperatures, and pH conditions;

[0027] Figure 3h O2 production by MZ under different material concentrations and pH conditions;

[0028] Figure 3i Photothermal map of MZ changing with visible light power;

[0029] Figure 4a Fiber physical picture;

[0030] Figure 4b SEM images of PVDF and P@MZ fibers;

[0031] Figure 4c Photothermal performance map of nanofiber dressing;

[0032] Figure 4d XRD, FTIR, and DSC spectra of nanofiber dressing;

[0033] Figure 4e Piezoelectric current of nanofiber dressings;

[0034] Figure 5a Under different stimulation conditions, different groups and MRSA, MRD. E. coli The coating results of the treated flat plate;

[0035] Figure 5b According to the plate coating results, the corresponding MRSA, MRD. E. coli Quantification of survival rate (n = 3);

[0036] Figure 5c Under different stimulation conditions, different groups and MRSA, MRD. E. coli SEM images after treatment;

[0037] Figure 6a Representative photos of skin wounds on days 0, 3, 7, and 12 after treatment in different groups;

[0038] Figure 6b Photos of plate spreads on days 3, 7, and 12 after treatment with different groups.

[0039] Figure 7 It is the overall flow chart of the present invention. Figure 7Molybdenum powders, H2O2, ZnFe2O4, MoO3-x / ZnFe2O4 composite materials; PVDF, mixed solution, nanofiber receiving device, PVDF@MoO3-x / ZnFe2O4 (nanofiber dressing - P@MZ); US, light. DETAILED DESCRIPTION

[0040] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following examples. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection of the present invention.

[0041] Example 1:

[0042] like Figure 7 As shown, a method for preparing a composite nanomaterial comprises the following steps:

[0043] Step 1: MoO 3-x Preparation of (M):

[0044] 0.1919 g of molybdenum metal powder was dispersed in 24 mL of ethanol solution and stirred at room temperature. H2O2 (3 mL, 30%) was added to obtain a yellow solution. The solution was then transferred to a 50 mL polytetrafluoroethylene container and sealed in a stainless steel autoclave. The reaction was carried out at 160 °C for 12 h. After cooling to room temperature, the solution was washed with ethanol and water three times respectively and dried in vacuum at 60 °C overnight to obtain MoO 3-x (M) Powder.

[0045] MoO 3-x Structural characterization of (M):

[0046] Scanning electron microscope (SEM) images of M nanomaterials are shown in Figure 2. Figure 1a As shown, Figure 1a SEM spectrum of M nanomaterial, M is a flake nanomaterial. Its crystal structure was verified by X-ray powder diffractometer (XRD) analysis. The results are as follows Figure 1b As shown, Figure 1b The XRD pattern of M nanomaterials is consistent with that of JCPDS NO.5-0508 MoO 3-x Correspondingly, MoO 3-x (M) was successfully prepared.

[0047] Step 2: Preparation of ZnFe2O4(Z):

[0048] 0.164 g zinc chloride, 0.649 g ferric chloride hexahydrate, 0.240 g sodium citrate dihydrate, and 1.2 g sodium acetate were dispersed in 20 mL of ethylene glycol in sequence and dissolved by ultrasonication to obtain a reddish-brown mixed solution. The solution was then transferred to a 50 mL polytetrafluoroethylene container and reacted at 200°C for 12 h. After cooling to room temperature, the mixture was washed with ethanol and water three times, respectively, and dried at 60°C for 12 h to obtain ZnFe2O4 (Z) powder.

[0049] Structural characterization of ZnFe2O4 (Z):

[0050] The morphology of Z nanomaterials was obtained by SEM. Figure 2a As shown, Figure 2a The SEM image of Z nanomaterials shows that the obtained ZnFe2O4 (Z) is spherical. XRD analysis verifies its crystal structure. Figure 2b As shown, Figure 2b Figure 2 is the XRD pattern of Z nanomaterials. The obtained XRD pattern of Z corresponds to JCPDS 22-1012 ZnFe2O4, indicating that Z was successfully prepared.

[0051] Step 3: MoO 3-x Preparation of ZnFe2O4 (MZ) nanocomposites:

[0052] 0.1919 g of molybdenum metal powder was dispersed in 24 mL of ethanol solution and stirred at room temperature, and then H2O2 (3 mL, 30%) was added to obtain a yellow solution. Then 0.048 g of Z powder was dispersed in the above yellow solution, ultrasonically dispersed, transferred to a 50 mL polytetrafluoroethylene container, sealed in a stainless steel autoclave, and reacted at 160°C for 12 h. After cooling to room temperature, the mixture was washed with ethanol and water three times respectively, and dried in vacuum at 60°C overnight to obtain MZ nanocomposite materials.

[0053] MoO 3-x / Structural characterization of ZnFe2O4 (MZ):

[0054] The SEM image of MZ is shown in Figure 3a As shown, Figure 3a SEM images of the MZ nanocomposite. Morphological observations show that the Z nanoparticles are tightly loaded on the M nanosheets. The corresponding elemental mapping images are shown in Figure 4. Figure 3b As shown, Figure 3b The elemental mapping of the MZ nanocomposite showed the presence of Mo, O, Fe, and Zn elements, and the results further verified the uniform distribution of Z on the M nanosheets. Figure 3cAs shown in the XRD pattern, the characteristic peaks of the composite material are consistent with those of the single-component nanomaterial, confirming the successful preparation of the MZ nanocomposite material.

[0055] MoO 3-x / Photocatalytic and photothermal properties of ZnFe2O4 (MZ):

[0056] In order to evaluate whether the composite of the two materials can improve the photocatalytic performance of the nanomaterials, firstly, the photoluminescence (PL) spectroscopy was used to study the photogenerated charge separation ability of the nanocomposite material and the two single materials, e.g. Figure 3d As shown, Figure 3d The PL spectrum of the MZ nanocomposite shows that the fluorescence intensity of the MZ nanocomposite is significantly lower than that of M and Z, indicating that the recombination efficiency of photogenerated electrons and holes is reduced, the photocatalytic ability is improved, and the heterojunction is successfully constructed. Secondly, the electron spin resonance spectrometer (ESR) is used to detect the types of ROS generated by the MZ nanocomposite, such as Figure 3e As shown, Figure 3e MZ is produced in darkness and light respectively 1 ESR spectra of O2 and •OH, MZ has no 1 The production of O2 can produce singlet oxygen ( 1 O2), Z and MZ can produce •OH in the dark, which is due to the CDT performance of Z. Both can produce •OH under light, and the ROS intensity generated by MZ is stronger than that of M and Z, further verifying the successful construction of the heterojunction and significantly improving the photocatalytic ability.

[0057] In order to clarify the generation mechanism of the above ROS, the band gap and valence band of Z and M were tested respectively, and the conduction band was calculated, and then the band structure of the MZ composite material was obtained, as shown in Fig. Figure 3f As shown, Figure 3f The band structure of MZ nanocomposite materials, Z and M can form a Z-type heterojunction.

[0058] The POD enzyme activity of MZ was preliminarily evaluated by TMB colorimetric assay. Figure 3g As shown, Figure 3g The UV absorption spectrum of the TMB color development reaction catalyzed by MZ under different material concentrations, temperatures, and pH conditions showed that its POD enzyme activity had a certain concentration dependence, and the UV absorption value increased with increasing temperature, indicating that the POD enzyme activity was temperature-dependent. At the same time, the lower the pH, the better the enzyme activity.

[0059] MoO was assessed using a dissolved oxygen meter. 3-x / ZnFe2O4(MZ)CAT enzyme activity, Figure 3h As shown, Figure 3hUnder different material concentrations and pH conditions, MZ produces O2. As the material concentration increases, more O2 is produced, indicating that the enzyme activity is concentration-dependent. The ability to produce O2 at pH 7.4 is stronger than that at pH 5.5 and 6.5, indicating that CAT enzyme activity performs best at a neutral pH.

[0060] The photothermal performance of MZ was preliminarily evaluated, such as Figure 3i As shown, Figure 3i The photothermal spectrum of MZ with visible light power shows a certain dependence on visible light power. When the power reaches 1000 W / m 2 When the material temperature reaches about 50℃.

[0061] Step 4: PVDF@MoO 3-x Preparation of P@MZ nanocomposite fiber dressing

[0062] 0.216 g of MZ nanomaterial was weighed and dissolved in 10 mL of DMF (N,N-dimethylformamide). Ultrasonication was then applied for 30 minutes. Then, 2.4 g of PVDF powder (polyvinylidene fluoride) was added and magnetic stirring was performed at 42°C for 12 hours to prepare a PVDF spinning solution with a uniform MZ dispersion. Finally, the resulting spinning solution was used to produce a P@MZ composite nanofiber membrane using solution jet spinning technology.

[0063] (Specific parameters are: needle specification: 23 G, propulsion rate: 10 mL / h, receiving roller speed: 500 rpm, receiving distance: 30 cm, wind pressure: 120 MPa)

[0064] PVDF@MoO 3-x Structural characterization of P@MZ nanocomposite fiber dressing

[0065] Figure 4a This is a physical picture of PVDF and P@MZ fibers. The nanofibers provide a supporting platform for MZ, evenly fixing MZ on its surface and enhancing the photocatalytic and photothermal effects. Figure 4b The SEM images show the surface morphology of PVDF and P@MZ nanofibers. PVDF nanofibers have a uniform, continuous and smooth fiber structure. On the nanofiber membrane containing MZ, MZ nanoparticles attached to the surface of the nanofibers can be clearly seen.

[0066] PVDF@MoO 3-x Performance characterization of / ZnFe2O4 (P@MZ) nanocomposite fiber dressing:

[0067] The photothermal performance of P@MZ was evaluated, such as Figure 4cAs shown, Figure 4c Photothermal performance spectrum of nanofiber dressing, after doping with MZ, power 1000 W / cm 2 , after 10 min of illumination, P@MZ can rise to about 45℃.

[0068] The β-phase content of PVDF and P@MZ was preliminarily evaluated, e.g. Figure 4d As shown, Figure 4d The XRD, FTIR, and DSC spectra of the nanofiber dressing and the XRD and FTIR images of P@MZ show that after doping with MZ, the peak intensity of the α phase of the P@MZ fiber membrane dressing decreases compared with PVDF, and the peak intensity of the β phase increases. In differential scanning calorimetry (DSC), PVDF shows a melting point peak at 168.64°C, while P@MZ shows a melting point peak at 170.64°C. This is because the melting point of the β phase is higher than that of the α phase. Due to the presence of MZ nanoparticles, the β phase content of the MZ@P fiber membrane is increased, resulting in the melting point of MZ@P being significantly higher than that of PVDF. This shows that doping with MZ can effectively improve the piezoelectric properties of PVDF. As shown in Table 1, the β-phase content of the PVDF fiber membrane prepared by SBS is 81.80%. The β-phase content of the PVDF fiber membrane prepared in the first related literature is 48.00%. In comparison, the β-phase content of the PVDF fiber membrane prepared by our method is 33.80% higher. In addition, the β-phase content of P@MZ is 93.95%, indicating that doping MZ can effectively improve the piezoelectric properties of PVDF.

[0069] The piezoelectric current generation of P@MZ nanofiber dressing was preliminarily evaluated by electrochemical workstation, such as Figure 4e As shown, Figure 4e The piezoelectric current of the nanofiber dressing is subjected to an ultrasonic on-off cycle every 40 s. It can be seen that no piezoelectric current is generated when no external ultrasound is applied. On the contrary, piezoelectric current is generated when a certain amount of external ultrasound is applied, which further illustrates the piezoelectric properties of the nanofiber dressing P@MZ.

[0070]

[0071] Example 2:

[0072] The invention discloses an application of a piezoelectrically enhanced antibacterial composite nano-dressing in the preparation of a dressing drug for treating external wounds of diabetic patients.

[0073] Antibacterial properties of PVDF@MoO3-x / ZnFe2O4 (P@MZ) nanocomposite fiber dressing:

[0074] The PVDF and PVDF@MoO were preliminarily evaluated by the coating plate method. 3-xThe antibacterial properties of (P@M), PVDF@Zn2FeO4 (P@Z), and P@ZM nanofibers were investigated. The flat coating method visually demonstrated the inactivation ability of P@MZ against drug-resistant Staphylococcus aureus (MRSA). Figure 5a As shown in Figures 1 and 2, in the dark, PBS (Blank), PVDF, and P@M have little to no bacterial inactivation ability, while P@Z and P@MZ have weak bacterial killing ability, which is attributed to the CDT properties of Z. The Light+ice group illustrates the bacterial inactivation effect of ROS generated by different groups under light alone. MZ effectively enhances the photocatalytic performance of the nanocomposite by constructing a Z-type heterojunction. Therefore, P@MZ effectively increases ROS production under light irradiation, further enhancing its bacterial inactivation effect. The Light group further demonstrates the effect of heat-promoted CDT. Compared with the Light+ice group, P@MZ significantly enhances its bacterial killing ability under light irradiation. While heat inhibits bacterial growth, heat promotes ROS production. This synergistic photocatalytic / photothermal effect significantly enhances the antibacterial ability of P@MZ. Under external ultrasound, Except for the PBS group, the other groups all had a certain antibacterial effect, which was due to the piezoelectric properties of PVDF. At the same time, since the doping of MZ enhanced the piezoelectricity of PVDF itself, the inactivation effect of P@MZ on bacteria was significantly improved. Finally, under the dual stimulation of light and ultrasound, the inactivation effect of bacteria basically reached 99%. This is the antibacterial effect of the piezoelectric enhanced nanocomposite fiber membrane dressing. Figure 5a And as shown in 5b: Figure 5a Under different stimulation conditions, different groups and MRSA, MRD. E. coli The coating results of the treated flat plate; Figure 5b According to the plate coating results, the corresponding MRSA, MRD. E. coli Quantification of survival rate (n=3).

[0075] Subsequently, the bacterial morphology of the two drug-resistant bacteria after incubation with the fiber membrane under different stimulation conditions was observed by scanning electron microscopy. Under dark conditions, only the bacteria incubated with P@MZ showed damage in morphology, while the bacteria in the PVDF group and the control group had smooth morphology and intact cell membranes; under visible light irradiation, whether it was after adding ice or removing the ice, the bacteria incubated with P@MZ showed varying degrees of wrinkles and ruptures in morphology, while the bacteria in the PVDF group and the control group had smooth morphology and intact cell membranes; under the action of simple ultrasound, except for the bacteria treated in the control group that showed a smooth surface morphology, the bacteria incubated with PVDF and P@MZ showed varying degrees of wrinkles and ruptured cell membrane morphology; under the dual stimulation of light and ultrasound, the bacteria treated with P@MZ had the most serious cell membrane damage and volume shrinkage, which may be caused by excessive leakage of bacterial contents. Figure 5c As shown, Figure 5c Under different stimulation conditions, different groups and MRSA, MRD. E. coli SEM images after treatment.

[0076] PVDF@MoO 3-x / ZnFe2O4 (P@MZ) nanocomposite fiber dressing promotes wound healing in diabetic mice:

[0077] To evaluate the promoting effects of P@MZ fiber membrane on wound healing, anti-inflammation, and angiogenesis in diabetic mice infected with Staphylococcus aureus, a full-thickness skin wound model was established.

[0078] The wounds were treated as follows: the control group was treated with a breathable sealing film; the third group was treated with a 3M commercial dressing; the PVDF group was treated with a sterile PVDF dressing followed by a 1M ultrasound therapy device for 10 minutes; the P@MZ group was treated with a sterile P@MZ dressing followed by a 1M ultrasound therapy device for 10 minutes; the P@MZ+Light group was treated with a sterile P@MZ+Ligh dressing followed by a 1M ultrasound therapy device for 10 minutes, while simultaneously receiving 1000W / m 2 lighting processing.

[0079] On day 1, a MRSA suspension was injected orally into the wound site. Significant bacterial proliferation and suppuration were observed at the wound site, indicating the successful establishment of a MRSA-infected diabetic mouse model (day 0). Images of the wound sites were captured using a digital camera on days 0, 3, 7, and 12 to observe wound healing under different treatment conditions. On day 0, there was no significant difference in wound area between the different groups, indicating that the full-thickness skin wounds were uniformly rounded. Over time, suppuration continued in all groups on day 3, but compared to the control group, the wounds in all groups showed a tendency to shrink. By day 7, the group treated with visible light irradiation and ultrasound stimulation on the P@MZ fiber dressing (P@MZ+Light+US group) demonstrated significant wound healing, demonstrating the excellent synergistic antibacterial effect of PTT / PCAT / POD. The elimination of bacteria from the wound site significantly promoted wound healing and prevented wound healing stagnation caused by infection and inflammation. By the 12th day, the wounds in the P@MZ+Light+US group were almost completely healed, which shows that the built-in electric field formed by P@MZ under ultrasound stimulation effectively promotes the proliferation and migration of damaged tissues, thereby promoting wound healing. This is consistent with the results of in vitro electrical stimulation promoting the proliferation and migration of L929 cells. Figure 6a As shown, Figure 6a Representative photos of skin wounds on days 0, 3, 7, and 12 after treatment in different groups.

[0080] Wound tissue samples were homogenized and applied on days 3, 7, and 12 of treatment to evaluate the in vivo antimicrobial efficacy of the P@MZ fiber dressing. On day 3, a significant number of bacterial colonies remained on the 3M dressing compared to the control group. Interestingly, both PVDF and P@MZ demonstrated moderate antimicrobial efficacy. This may be because MRSA-infected diabetic wounds are typically moist due to the presence of pus. Therefore, under ultrasound, the charges from wound electrolytes can interact with oxygen or water molecules, generating ROS, which inactivate bacteria within the wound. Illumination significantly enhanced the in vivo antimicrobial efficacy, driven by the heat generated and the resulting photocatalytic effect. Furthermore, the POD in the wound reacts with H₂O₂ secreted by wound bacteria to produce •OH, which also has a bacterial killing effect. On day 7, the number of bacterial colonies in the illuminated group was significantly reduced compared to day 3, demonstrating the effective in vivo antimicrobial efficacy of PTT / PCAT / POD against drug-resistant bacteria. On the 12th day of treatment, the number of colonies in the control group and the 3M dressing group decreased significantly, which was due to the action of the mice's own immune system. It is worth noting that the in vivo antibacterial efficiency of the P@MZ+Light+US group was significantly improved on the 12th day, which was based on the significant improvement in the wound healing rate of the mice on the 12th day of treatment. Figure 6b As shown, Figure 6b Photos of plate spreads on days 3, 7, and 12 after treatment with different groups.

[0081] The foregoing is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained herein shall, unless otherwise specified or limited, be implemented in accordance with conventional means in the art.

Claims

1. A method for preparing a piezoelectric enhanced antibacterial composite nano-dressing, characterized by: The following steps are involved: Step 1: Disperse 0.164 g zinc chloride, 0.649 g ferric chloride hexahydrate, 0.240 g sodium citrate dihydrate, and 1.2 g sodium acetate in 20 mL of ethylene glycol in sequence. Dissolve them by ultrasonication to obtain a reddish-brown mixed solution. Transfer the solution to a polytetrafluoroethylene container and react at 200°C for 12 h. After cooling to room temperature, wash with ethanol and water three times, respectively, and dry at 60°C for 12 h to obtain ZnFe2O4 powder. Step 2: 0.1919 g of molybdenum metal powder was dispersed in 24 mL of ethanol solution and stirred at room temperature, and then H2O2 was added to obtain a yellow solution. Then, 0.048 g of ZnFe2O4 powder was dispersed in the above yellow solution, and after ultrasonic dispersion, it was transferred to a polytetrafluoroethylene container and sealed in a stainless steel autoclave. The reaction was carried out at 160 ° C for 12 h, and after cooling to room temperature, it was washed with ethanol and water three times respectively, and dried in vacuum at 60 ° C overnight to obtain MoO 3-x / ZnFe2O4 nanocomposite materials; Step 3: MoO 3-x The MoO / ZnFe2O4 nanocomposite was dissolved in 10 mL N,N-dimethylformamide and ultrasonicated for 30 min. Then 2.4 g of polyvinylidene fluoride powder was added and magnetically stirred at 42 °C for 12 h to prepare MoO 3-x / ZnFe2O4 nanocomposite material is evenly dispersed in a polyvinylidene fluoride spinning solution; finally, the obtained spinning solution is subjected to solution jet spinning technology to obtain PVDF@MoO 3-x / ZnFe2O4 composite nanofiber membrane; MoO 3-x / ZnFe2O4 nanocomposites include the construction of Z-type heterojunctions.

2. The method for preparing a piezoelectric enhanced antibacterial composite nano-dressing according to claim 1, characterized in that: In step 3, the specific parameters of the solution jet spinning technology are: needle specification: 23 G, propulsion rate: 10 mL / h, receiving roller speed: 500 rpm, receiving distance: 30 cm, and wind pressure: 120 MPa.

3. Use of the piezoelectric enhanced antibacterial composite nano dressing prepared according to the method described in claim 2 in treating external wound dressings of diabetic patients.

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