Multifunctional electrospun nanofiber with bacteriostatic and anti-tumor effects as well as preparation method and application of multifunctional electrospun nanofiber

Abstract

The invention relates to the technical field of nano materials, in particular to a multifunctional electrospun nanofiber with bacteriostatic and anti-tumor effects and a preparation method and application of the multifunctional electrospun nanofiber. The result of the specific embodiment of the invention proves that the polyethylene oxide / gellan gum-carvacrol electrospun nanofiber can prolong the shelf life of strawberries by 3-4 days, and effectively alleviates the weight loss ratio, hardness, acidity, color and other quality deterioration of strawberry fruits. Microbial colony structure analysis shows that PEO / GG-CAR treatment can effectively reduce the flora richness and species number of strawberries, inhibit related putrefying bacteria such as proteobacteria, and promote the relative abundance of anaerobic microorganisms such as firmicobacteria and the like to be improved at the same time. Principal component analysis proves that the electrospun nanofiber membrane added with the CAR can effectively regulate microbial communities of strawberries, so that the preservative and fresh-keeping effects are achieved. Meanwhile, the electrospun nanofiber membrane also has the effect of inhibiting cancer cells.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a multifunctional electrospun nanofiber with antibacterial and antitumor effects, and a preparation method and application thereof. Background Art

[0002] With rapid socioeconomic development and shifting consumer attitudes, consumers are placing higher safety demands on food packaging. The research and development of functional packaging materials has shifted to the multiple goals of ensuring food safety while also achieving environmental friendliness and effectively extending food shelf life. Traditional plastic packaging, due to inherent drawbacks such as difficulty in degradation and environmental pollution, and its limited physical barrier properties, struggles to meet the growing market demand for food packaging. The development of environmentally friendly active packaging materials is crucial for ensuring food quality and safety and extending shelf life. Research has demonstrated that antibacterial packaging materials developed using electrospinning technology can effectively inhibit microbial growth, providing an innovative solution for extending the shelf life of food. The safety of antibacterial packaging materials prepared by electrospinning depends primarily on the selected substrate. As a synthetic polymer, polyethylene oxide (PEO) has significant application potential in electrospinning due to its excellent biocompatibility, degradability, and film-forming properties. However, its strong hydrophilicity has limited its widespread application in food packaging. The natural polysaccharide gellan gum (GG) not only has good safety and biodegradability, but also improves the thermal stability of films and exhibits antibacterial and fresh-keeping effects. It has also been reported that bacterial infection and inflammation can induce tumors. Currently, the commonly used antibacterial strategy is to introduce antibacterial components into carriers, but most of these have drawbacks such as uneven distribution and strong toxic side effects. Currently, there are few reports on the use of PEO and GG as substrates to load bioactive substances to prepare food active packaging materials or anti-tumor drugs. Summary of the Invention

[0003] The purpose of the present invention is to provide a multifunctional electrospun nanofiber with antibacterial and antitumor effects, and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a method for preparing polyethylene oxide / gellan gum-carvacrol electrospun nanofibers (PEO / GG-CAR or PEO / GG-CAR electrospun nanofiber membranes), comprising the following steps:

[0006] performing electrostatic spinning treatment on polyethylene oxide to obtain a polyethylene oxide spinning solution;

[0007] mixing the polyethylene oxide spinning solution and the gellan gum solution to obtain a polyethylene oxide / gellan gum blended spinning solution;

[0008] After the polyethylene oxide / gellan gum blend spinning solution and carvacrol are mixed, Tween 80 is added, and stirring and shearing are performed to obtain the polyethylene oxide / gellan gum-carvacrol electrospun nanofibers.

[0009] Preferably, the mass ratio of the polyethylene oxide spinning solution to the gellan gum solution is (6-9):(1-4);

[0010] The concentration of polyethylene oxide in the polyethylene oxide spinning solution is 5%-8%;

[0011] The concentration of gellan gum in the gellan gum solution is 1.5%;

[0012] The amount of carvacrol used is 1%-5% of the mass of the polyethylene oxide / gellan gum blended spinning solution.

[0013] Preferably, the mass ratio of the polyethylene oxide spinning solution to the gellan gum solution is 9:1;

[0014] The concentration of polyethylene oxide in the polyethylene oxide spinning solution is 7%;

[0015] The amount of carvacrol used is 3%-4% of the mass of the polyethylene oxide / gellan gum blended spinning solution.

[0016] Preferably, the amount of Tween 80 used is 2% by mass of the mixed solution obtained by mixing the polyethylene oxide / gellan gum blend spinning solution and carvacrol.

[0017] The present invention provides polyethylene oxide / gellan gum-carvacrol electrospun nanofibers obtained by the above preparation method.

[0018] The present invention provides the use of the above-mentioned polyethylene oxide / gellan gum-carvacrol electrospun nanofibers in any of the following

[0019] (1) Preparation of antibacterial film;

[0020] (2) Preparation of antibacterial drugs;

[0021] (3) preparing a fresh-keeping film;

[0022] (4) preparing a preservative;

[0023] (5) Preparation of anti-tumor drugs.

[0024] Preferably, the pathogenic bacteria targeted by the antimicrobial film or antimicrobial drug include one or more of Staphylococcus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, cluster A type B hemolytic Streptococcus, Streptococcus mutans, Streptococcus sanguis, Actinomyces naeslundii, acid-fast bacteria, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, Veillonella, Candida albicans, Salmonella, Listeria monocytogenes, Pseudomonas aeruginosa, Bacillus cereus, Bacillus stearothermophilus, Clostridium thermosaccharolyticum, Clostridium niger, Clostridium botulinum, Helicobacter pylori, Enterococcus faecalis, toxigenic Bacteroides fragilis and Streptococcus bovis; the Salmonella includes Salmonella typhimurium and / or Salmonella pullorum; the Staphylococcus includes one or more of Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus albus;

[0025] The tumor includes one or more of colorectal cancer, gastric cancer, cervical cancer, ovarian cancer, breast cancer, thyroid cancer, prostate cancer, pancreatic cancer, glioma, bile duct cancer, liver cancer and lung cancer.

[0026] The present invention provides an antibacterial film or antibacterial drug, comprising the above-mentioned polyethylene oxide / gellan gum-carvacrol electrospun nanofibers.

[0027] Further preferably, the antibacterial film comprises an antibacterial packaging film.

[0028] Further preferably, the pathogenic bacteria targeted by the antimicrobial film or antimicrobial drug include one or more of Staphylococcus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, cluster A type B hemolytic Streptococcus, Streptococcus mutans, Streptococcus sanguis, Actinomyces naeslundii, acid-fast bacteria, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, Veillonella, Candida albicans, Salmonella, Listeria monocytogenes, Pseudomonas aeruginosa, Bacillus cereus, Bacillus stearothermophilus, Clostridium thermosaccharolyticum, Clostridium niger, Clostridium botulinum, Helicobacter pylori, Enterococcus faecalis, toxigenic Bacteroides fragilis and Streptococcus bovis; the Salmonella includes Salmonella typhimurium and / or Salmonella pullorum; the Staphylococcus includes one or more of Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus albus;

[0029] The tumor includes one or more of colorectal cancer, gastric cancer, cervical cancer, ovarian cancer, breast cancer, thyroid cancer, prostate cancer, pancreatic cancer, glioma, bile duct cancer, liver cancer and lung cancer.

[0030] Further preferably, the dosage form of the antibacterial drug includes gel preparation, liquid preparation and solid preparation.

[0031] Further preferably, the gel preparation includes a vaginal gel preparation; the liquid preparation includes a solvent type, aqueous solution, glycerin agent, tincture, elixir, colloidal solution, suspension or emulsion; the solid preparation includes powder, granule, tablet or capsule.

[0032] The present invention provides a fresh-keeping film or a fresh-keeping agent, comprising the above-mentioned polyethylene oxide / gellan gum-carvacrol electrospun nanofibers.

[0033] Further preferably, the fresh-keeping film comprises a fresh-keeping packaging film.

[0034] The present invention provides an anti-tumor drug comprising the above-mentioned polyethylene oxide / gellan gum-carvacrol electrospun nanofibers.

[0035] Further preferably, the tumor includes one or more of colorectal cancer, gastric cancer, cervical cancer, ovarian cancer, breast cancer, thyroid cancer, prostate cancer, pancreatic cancer, glioma, bile duct cancer, liver cancer and lung cancer.

[0036] As an additional solution, the present invention provides a method for preserving fruit, comprising the step of applying the above-mentioned antibacterial material or preservative material to the fruit to be preserved.

[0037] The present invention discloses the following technical effects:

[0038] The present invention provides a polyethylene oxide / gellan gum-carvacrol electrospun nanofiber (PEO / GG-CAR or PEO / GG-CAR electrospun nanofiber membrane) and a preparation method thereof, and the results of the specific embodiments confirm that the PEO / GG-CAR electrospun nanofiber membrane can extend the shelf life of strawberries by 3-4 days, effectively slowing down the weight loss rate, hardness, acidity and color of strawberry fruits. Microbial colony structure analysis shows that PEO / GG-CAR treatment can effectively reduce the bacterial richness and species number of strawberries, inhibit related spoilage bacteria such as Proteobacteria, and promote the relative abundance of anaerobic microorganisms such as Firmicutes. Principal component analysis confirms that the electrospun nanofiber membrane with the addition of carvacrol (CAR) can effectively regulate the microbial community of strawberries, thereby playing an antiseptic and fresh-keeping role. At the same time, the electrospun nanofiber membrane also has the effect of inhibiting cancer cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1The apparent viscosity of PEO spinning solutions with different concentrations; A: Relationship curve between apparent viscosity and shear rate of PEO spinning solutions with different concentrations; B: Relationship between shear stress and shear rate of PEO spinning solutions with different concentrations. The red solid line is the fitting curve based on the Herschel-Bulkley model.

[0041] Figure 2 The SEM images and diameter distribution histograms of electrospun nanofibers with different concentrations of PEO are shown in Figure 2. The concentrations of PEO in AD are 5%, 6%, 7%, and 8% (w / v), respectively. av : average nanofiber diameter;

[0042] Figure 3 The apparent viscosity of PEO / GG spinning solutions with different mass ratios; A: Relationship curve between apparent viscosity and shear rate of PEO / GG spinning solutions with different mass ratios; B: Relationship between shear stress and shear rate of PEO / GG spinning solutions with different mass ratios. The red solid line is the fitting curve based on the Herschel-Bulkley model.

[0043] Figure 4 The SEM images and diameter distribution histograms of PEO / GG electrospun nanofibers with different mass ratios are shown in Figure 2. The mass ratios of PEO / GG in AE are 10:0, 9:1, 8:2, 7:3 and 6:4 respectively; D av : average nanofiber diameter;

[0044] Figure 5 Fourier transform infrared spectra of PEO / GG electrospun nanofibers and powder samples with different mass ratios;

[0045] Figure 6 XRD spectra of PEO / GG electrospun nanofibers and powder samples with different mass ratios;

[0046] Figure 7 TGA curves (A) and DTG curves (B) of PEO / GG electrospun nanofibers and powder samples with different mass ratios;

[0047] Figure 8 DSC curves of PEO / GG electrospun nanofibers and powder samples with different mass ratios;

[0048] Figure 9 The apparent viscosity of the spinning solution with different CAR addition amounts; A: Relationship curve between apparent viscosity and shear rate of the spinning solution with different CAR addition amounts; B: Relationship between shear stress and shear rate of the spinning solution with different CAR addition amounts. The red solid line is the fitting curve based on the Herschel-Bulkley model.

[0049] Figure 10 Effects of different CAR addition amounts on the particle size (A), Zeta potential (B) and PDI (C) of the emulsion;

[0050] Figure 11 Effects of different CAR addition amounts on the microstructure and appearance of the emulsion; A: PEO / GG-CAR1; B: PEO / GG-CAR2; C: PEO / GG-CAR3; D: PEO / GG-CAR4; E: PEO / GG-CAR5; F: appearance of the emulsion;

[0051] Figure 12 The SEM images and diameter distribution histograms of electrospun nanofibers with different CAR addition amounts are shown; AE are electrospun nanofibers with CAR addition amounts of 0%, 1%, 2%, 3% and 4% (w / w), respectively; D av : average nanofiber diameter;

[0052] Figure 13 TEM images of PEO / GG-CAR emulsion electrospun nanofibers; A is the uniform oil droplets arranged axially in the smooth electrospun nanofiber; B is the large oil droplets inside the beaded electrospun nanofiber;

[0053] Figure 14 Fourier transform infrared spectra of electrospun nanofibers and CAR with different CAR addition amounts;

[0054] Figure 15 XRD spectra of electrospun nanofibers with different CAR addition amounts;

[0055] Figure 16 TGA curves (A) and DTG curves (B) of electrospun nanofibers with different CAR addition amounts;

[0056] Figure 17 DSC curves of electrospun nanofibers with different CAR addition amounts;

[0057] Figure 18 Water contact angle of electrospun nanofiber membranes with different CAR addition amounts;

[0058] Figure 19 Mechanical properties of electrospun nanofiber membranes with different CAR addition amounts; A: stress-strain curve; B: elongation at break and tensile strength;

[0059] Figure 20 The antioxidant activity of electrospun nanofiber membranes with different CAR addition amounts;

[0060] Figure 21The inhibition zone images of PEO / GG-CAR electrospun nanofiber membrane against Staphylococcus aureus and Escherichia coli;

[0061] Figure 22 SEM images of Staphylococcus aureus before and after treatment with PEO / GG-CAR4 electrospun nanofiber membrane;

[0062] Figure 23 The inhibitory effect of PEO / GG-CAR electrospun nanofiber membrane on Staphylococcus aureus biofilm; A: crystal violet staining image; B: inhibition rate of nanofiber membrane on biofilm; C: laser confocal microscopy observation of biofilm morphology;

[0063] Figure 24 The effects of different treatments on the surface morphology of strawberries;

[0064] Figure 25 The effect of different treatments on the weight loss rate of strawberries;

[0065] Figure 26 The effects of different treatments on the firmness of strawberries;

[0066] Figure 27 The effects of different treatments on pH value of strawberry;

[0067] Figure 28 The effects of different treatments on the titratable acid content of strawberries;

[0068] Figure 29 The effect of different treatments on the color difference of strawberries;

[0069] Figure 30 is the Alpha diversity index box plot;

[0070] Figure 31 The bar graphs are for species composition and difference analysis at the phylum level;

[0071] Figure 32 The bar graphs are for species composition and difference analysis at the genus level;

[0072] Figure 33 Principal component analysis;

[0073] Figure 34 The anticancer activities of different treatments. DETAILED DESCRIPTION

[0074] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0075] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0076] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0077] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0078] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0079] Unless otherwise specified, the materials used in the present invention are all materials commonly purchased by those skilled in the art, and the methods used in the present invention are all methods well known to those skilled in the art.

[0080] Raw materials and reagents for the present invention: Strawberries and absorbent pads were purchased from a supermarket in Harbin. The main raw materials and chemical reagents for the experiment are shown in Table 1.

[0081] Table 1 Experimental raw materials and reagents

[0082] Reagent name source Polyethylene oxide (Mw~300000Da) Shanghai MacLean Biochemical Technology Co., Ltd. Gellan gum Shanghai MacLean Biochemical Technology Co., Ltd. Carvacrol Shanghai Yuanye Biotechnology Co., Ltd. Twain 80 Shanghai Yuanye Biotechnology Co., Ltd. Staphylococcus aureus CMCC29213 (S. aureus CMCC29213) Laboratory storage Escherichia coli ATCC25922 Laboratory storage MHA medium Beijing Aoboxing Biotechnology Co., Ltd. MHB medium Beijing Aoboxing Biotechnology Co., Ltd. PCA plate count agar medium Beijing Aoboxing Biotechnology Co., Ltd. PBS buffer Biotopped ABTS Shanghai Aladdin Biochemical Technology Co., Ltd. DPPH Shanghai Aladdin Biochemical Technology Co., Ltd. glacial acetic acid Tianjin Komeo Chemical Reagent Company Anhydrous ethanol Tianjin Komeo Chemical Reagent Company

[0083] Example 1 Characterization of electrospun nanofibers

[0084] 1 Test method

[0085] 1.1 Preparation of electrospun nanofibers with different concentrations of polyethylene oxide

[0086] 1.1.1 Preparation of polyethylene oxide spinning solutions with different concentrations

[0087] Weighed polyethylene oxide (PEO) powder was added to 20 mL of deionized water and stirred continuously at 60°C using a magnetic stirrer for 4 hours to prepare 5%, 6%, 7%, and 8% (w / v) PEO spinning solutions. After the solutions were thoroughly mixed and allowed to stand to eliminate bubbles, the resulting PEO spinning solutions were cooled to 25°C and stored until ready for use.

[0088] 1.1.2 Analysis of properties of polyethylene oxide spinning solutions at different concentrations

[0089] The electrical conductivity, apparent viscosity and pH value of electrospun nanofibers with different concentrations of polyethylene oxide were tested.

[0090] 1.1.3 Preparation of electrospun polyethylene oxide nanofibers with different concentrations

[0091] The electrospinning process was performed in a horizontal mode using a high-voltage power supply, syringe pusher, and receiver plate. PEO spinning solutions of varying concentrations were injected into a 5 mL syringe fitted with a 21G needle (0.51 mm inner diameter). The electrospinning process was performed under the following parameters: a flow rate of 0.48 mL / h, a forward voltage of 15 kV, and a tip-to-receiver plate distance of 15 cm. Electrospun nanofiber membranes were prepared under ambient conditions of 25 ± 1°C and 50 ± 1% relative humidity.

[0092] 1.1.4 Analysis of the morphology and diameter of electrospun nanofibers of polyethylene oxide at different concentrations

[0093] Scanning electron microscopy (SEM) was used to characterize the morphology of electrospun nanofibers with varying PEO concentrations. The samples were gold-sprayed for 60 seconds under an inert N2 atmosphere to enhance conductivity and then observed at an accelerating voltage of 5 kV. Images were selected and saved at magnifications of 5000x and 10,000x. Fifty nanofibers were randomly sampled from the SEM images, and the diameter distribution of the electrospun nanofibers with varying PEO concentrations was analyzed using ImageJ software.

[0094] 1.2 Preparation and characterization of polyethylene oxide / gellan gum electrospun nanofibers

[0095] 1.2.1 Preparation of polyethylene oxide / gellan gum blend spinning solutions with different mass ratios

[0096] PEO / gellan gum (GG) blend spinning solutions with different mass ratios were prepared by mixing 7% (w / v) PEO spinning solution and 1.5% (w / v) GG solution in mass ratios of 10:0, 9:1, 8:2, 7:3, and 6:4, respectively. The total mass of the mixed solution was 20 g and magnetically stirred at 60°C for 1 h.

[0097] 1.2.2 Analysis of properties of polyethylene oxide / gellan gum blend spinning solutions with different mass ratios

[0098] The conductivity, apparent viscosity and pH of polyethylene oxide / gellan gum blend spinning solutions with different mass ratios were tested.

[0099] 1.2.3 Preparation of polyethylene oxide / gellan gum electrospun nanofibers with different mass ratios (PEO / GG electrospun nanofibers) PEO / GG electrospun nanofibers with different mass ratios were prepared according to the method in "1.1.3".

[0100] 1.2.4 Structural Characterization of Polyethylene Oxide / Gellan Gum Electrospun Nanofibers with Different Mass Ratios

[0101] (1) Scanning electron microscope observation (SEM): the steps are the same as “1.2.1.4”.

[0102] (2) Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR): The molecular structure and chemical bonds of PEO powder, GG powder and PEO / GG electrospun nanofibers with different mass ratios were analyzed by Fourier transform infrared spectroscopy. The spectral resolution was 4 cm -1 , scanning wavelength range is 4000 to 400 cm -1 , the cumulative number of scans is 32 times.

[0103] (3) X-ray diffraction analysis (XRD): The crystal structures of PEO powder, GG powder, and PEO / GG electrospun nanofibers with different mass ratios were analyzed using an X-ray diffraction analyzer. Cu-Kα radiation was used as the X-ray source, with the operating voltage and current set to 40 kV and 30 mA, respectively. Diffraction data were collected over a 2θ angle range of 5°–85° at a scanning speed of 2° / min.

[0104] (4) Thermogravimetric analysis (TGA): The thermal stability of PEO powder, GG powder, and PEO / GG electrospun nanofibers with different mass ratios was analyzed by thermogravimetric analysis. A crucible containing 10 mg of sample was heated from 25°C to 600°C at a heating rate of 10°C / min in a nitrogen atmosphere.

[0105] (5) Differential Scanning Calorimetry (DSC): Approximately 5 mg of PEO powder, GG powder, and PEO / GG electrospun nanofibers with different mass ratios were weighed into an alumina crucible and tested using a differential scanning calorimeter under nitrogen protection. The scan rate was 10°C / min, and the temperature range was 20°C–180°C.

[0106] 1.3 Preparation and characterization of polyethylene oxide / gellan gum-carvacrol electrospun nanofibers

[0107] 1.3.1 Preparation of Polyethylene Oxide / Gellan Gum-Carvacrol Spinning Solution (Polyethylene Oxide / Gellan Gum-Carvacrol Electrospun Nanofibers)

[0108] Based on the PEO / GG spinning solution with the optimal mass ratio screened out by "1.2", 0%, 1%, 2%, 3%, 4%, and 5% (w / w) carvacrol (CAR) relative to the total mass of the PEO and GG solutions was added. At the same time, 2% (w / w) Tween 80 was added to the spinning solution as an emulsifier. The electrospinning solution was magnetically stirred at room temperature for 5 hours to ensure complete dissolution. Then, the mixture was sheared for 5 minutes at a speed of 10,000 r / min using a high-speed shearing machine to prepare an oil-in-water emulsion. The spinning solutions with different concentrations of CAR added were labeled as PEO / GG-CAR0, PEO / GG-CAR1, PEO / GG-CAR2, PEO / GG-CAR3, PEO / GG-CAR4, and PEO / GG-CAR5.

[0109] 1.3.2 Analysis of spinning solution properties with different carvacrol addition amounts

[0110] The conductivity, apparent viscosity, pH value, particle size, Zeta potential and polydispersity coefficient of the spinning solution with different carvacrol addition amounts as well as the emulsion microstructure were tested.

[0111] Particle size, zeta potential, and polydispersity index (PDI) of the PEO / GG-CAR emulsion were measured using a nanoparticle size and zeta potential analyzer via dynamic light scattering. Prior to testing, the emulsion was diluted 1:500 with deionized water to eliminate multiple scattering effects. At least three replicates were performed at room temperature.

[0112] The microstructure of the PEO / GG-CAR emulsion was measured using an inverted microscope. First, the freshly prepared emulsion sample was diluted 100-fold with deionized water until translucent. An appropriate amount of the dilution was then dripped onto the center of a clean glass slide. The sample was allowed to equilibrate at room temperature for 2 minutes before microscopic observation at 40x magnification, and the corresponding image data was collected.

[0113] 1.3.3 Preparation of electrospun nanofibers with different carvacrol additions

[0114] Emulsion electrospun nanofibers with different CAR addition amounts were prepared according to the method in “1.3.1”.

[0115] 1.2.4 Structural characterization of electrospun nanofibers with different carvacrol addition amounts

[0116] The electrospun nanofibers with different carvacrol addition amounts were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), attenuated total reflection Fourier transform infrared spectroscopy, X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

[0117] 1.2.5 Water contact angle measurement of electrospun nanofibers with different carvacrol addition amounts

[0118] The emulsion electrospun nanofiber membranes with different carvacrol addition amounts were cut into 1×5 cm 2 The hydrophobicity of the samples was then measured by the sitting drop method using a video optical goniometer.

[0119] 1.2.6 Mechanical properties of electrospun nanofibers with different carvacrol additions

[0120] The stress-strain curves of electrospun nanofiber membranes with different amounts of carvacrol were determined using a texture analyzer, and the elongation at break (EB) and tensile strength (TS) were calculated. The steps were as follows: the electrospun nanofiber membranes were cut into 10 mm × 50 mm strips for testing; the trigger force was set to 3 g, the test speed was set to 3 mm / s, and the clamp stretching distance was set to 10 cm.

[0121] 1.2.7 Determination of the antioxidant properties of electrospun nanofibers with different carvacrol additions

[0122] 10 mg of electrospun nanofibers were dissolved in 1 mL of PBS, vortexed for 10 min, and eluted with DPPH and ABTS. + The test was carried out as follows: 1 mL of the sample solution to be tested was added with 5 mL of 0.1 mmol / L DPPH solution, mixed thoroughly and allowed to stand in the dark for 15 min, and then the absorbance was measured at a wavelength of 517 nm using a UV-visible spectrophotometer. In addition, 1 mL of the sample solution was mixed with 5 mL of 7 mmol / L ABTS + The solutions were mixed and reacted in the dark for 15 minutes, and then the absorbance was measured at 734 nm. The antioxidant activity of the electrospun nanofiber membrane was calculated using the following formula:

[0123]

[0124] Where A0 represents the absorbance of the solution containing only DPPH; A f Represents the absorbance of the sample.

[0125]

[0126] Where A0 represents the absorbance of the solution containing only ABTS; A fRepresents the absorbance of the sample.

[0127] 1.3 Statistical analysis

[0128] All experiments were repeated three times, and data are presented as mean ± standard deviation. Data were analyzed using SPSS 25.0 statistical software. One-way analysis of variance (ANOVA) was used for intergroup comparisons, and Turkey's test was used for multiple comparisons. P < 0.05 indicated a significant difference. Data visualization was created using Origin 2021 software. Significant differences in the charts are indicated by different letters.

[0129] 2 Results and Analysis

[0130] 2.1 Research on electrospun polyethylene oxide nanofibers

[0131] 2.1.1 Effect of polyethylene oxide concentration on spinning solution properties

[0132] As shown in Table 2, the pH value showed an upward trend with increasing PEO solution concentration, but there was no significant difference in pH between 6% and 7% PEO solutions. When the PEO solution concentration increased from 5% to 8%, the conductivity increased significantly (P < 0.05), from (135.84 ± 0.04) μS / cm to (152.93 ± 0.03) μS / cm. Figure 1 A in the figure shows the relationship between the apparent viscosity and shear rate of PEO solutions of different concentrations. As the shear rate increases, the apparent viscosity of PEO solutions of all concentrations gradually decreases and eventually stabilizes. When the concentration of PEO solution exceeds 7%, the viscosity begins to rise sharply. The relationship between shear stress and shear rate of PEO solutions of different concentrations is shown in Figure 1. Figure 1 As shown in B, σ0, K, n and R 2 The relevant rheological parameters are shown in Table 2. σ0 represents the yield stress. When the applied shear stress exceeds the corresponding σ0, the PEO solution will flow. The change in K value reflects that the viscosity of the spinning solution increases with the increase in PEO concentration. All n values ​​are less than 1, which confirms that PEO solutions of different concentrations are pseudoplastic fluids among non-Newtonian fluids. 2 >0.99 indicates that the Herschel-Bulkley model fits the data well.

[0133] Table 2 pH value, conductivity and Herschel-Bulkley model rheological parameters of PEO solutions with different concentrations

[0134] Spinning solution pH Conductivity (μS / cm) <![CDATA[σ0(Pa)]]> <![CDATA[K(Pa·S n )]]> n <![CDATA[R 2 ]]> 5% PEO <![CDATA[7.96±0.01 c ]]> <![CDATA[135.84±0.04 d ]]> 0.000±0.040 0.432±0.007 0.877±0.003 0.999 6% PEO <![CDATA[8.17±0.01 b ]]> <![CDATA[147.82±0.03 c ]]> 0.000±0.111 0.949±0.025 0.815±0.005 0.999 7% PEO <![CDATA[8.20±0.01 b ]]> <![CDATA[151.71±0.02 b ]]> 0.000±0.286 2.324±0.077 0.747±0.007 0.999 8% PEO <![CDATA[8.24±0.01 a ]]> <![CDATA[152.93±0.03 a ]]> 0.000±0.469 3.697±0.132 0.732±0.007 0.999

[0135] Note: Different lowercase letters indicate significant differences (P<0.05), the same as in the following table.

[0136] 2.1.2 Effect of polyethylene oxide concentration on the morphology of electrospun nanofibers

[0137] like Figure 2 As shown, at PEO concentrations of 5%, 6%, 7%, and 8%, the diameters of the electrospun nanofibers were (118.82±27.85), (202.82±40.09), (275.56±47.25), and (312.12±46.15) nm, respectively. A low 5% PEO solution formed a large number of non-uniform fibers with beads, accompanied by significant fiber breakage. Increasing the PEO solution concentration from 5% to 8% resulted in a continuous increase in the average fiber diameter. Further increasing the PEO solution concentration to 7% and 8% improved the electrospinning efficiency, maintaining uniform fiber thickness, good morphology, and the absence of beads. Only the nanofiber diameter continued to increase. During the electrospinning process, considering key factors such as nanofiber diameter uniformity, nanofiber morphological integrity, and raw material utilization, a 7% PEO spinning solution was selected for subsequent experiments.

[0138] 2.2 Study on electrospun polyethylene oxide / gellan gum nanofibers

[0139] 2.2.1 Property Analysis of Polyethylene Oxide / Gellan Gum Blend Spinning Solutions with Different Mass Ratios

[0140] As shown in Table 3, the pH values ​​of the PEO / GG blend spinning solutions at different mass ratios were significantly lower than those of pure PEO solutions (P < 0.05). When the mass ratio of the PEO / GG spinning solution changed from 9:1 to 6:4, the pH value of the spinning solution showed a downward trend, decreasing from 7.91 ± 0.02 to 7.67 ± 0.03. As the GG ratio in the PEO / GG spinning solution increased, the conductivity of the spinning solution significantly increased from (151.71 ± 0.02) μS / cm to (559.07 ± 0.12) μS / cm (P < 0.05). Figure 3 Figure A shows that the rheological behavior of PEO / GG spinning solutions with different mass ratios exhibits shear thinning characteristics. The relationship between shear stress and shear rate of PEO / GG spinning solutions with different mass ratios is shown in Figure 2. Figure 3 The relevant rheological parameters are shown in Table 3. The PEO / GG solution will only flow when the applied stress exceeds σ0. The change in K value reflects that the viscosity of the PEO / GG spinning solution increases with the increase in the proportion of GG in the solution system. All n values ​​are less than 1, which shows the pseudoplastic fluid characteristics of the PEO / GG spinning solution with different mass ratios. 2 >0.9 indicates that the Herschel-Bulkley model fits the data well.

[0141] Table 3 pH value, conductivity and Herschel-Bulkley model rheological parameters of PEO / GG spinning solutions with different mass ratios

[0142] Spinning solution pH Conductivity (μS / cm) <![CDATA[σ0(Pa)]]> <![CDATA[K(Pa·S n )]]> n <![CDATA[R 2 ]]> PEO / GG=10:0 <![CDATA[8.20±0.01 a ]]> <![CDATA[151.71±0.02 e ]]> 0.000±0.286 2.324±0.077 0.747±0.007 0.999 PEO / GG=9:1 <![CDATA[7.91±0.02 b ]]> <![CDATA[239.03±0.06 d ]]> 1.179±0.377 2.389±0.134 0.648±0.011 0.995 PEO / GG=8:2 <![CDATA[7.89±0.01 b ]]> <![CDATA[375.80±0.72 c ]]> 2.241±0.387 2.441±0.164 0.581±0.013 0.993 PEO / GG=7:3 <![CDATA[7.79±0.01 c ]]> <![CDATA[423.67±0.58 b ]]> 1.734±0.424 2.734±0.174 0.595±0.012 0.994 PEO / GG=6:4 <![CDATA[7.67±0.03 d ]]> <![CDATA[559.07±0.12 a ]]> 1.601±0.647 4.174±0.371 0.456±0.016 0.986

[0143] 2.2.2 Analysis of the morphology of polyethylene oxide / gellan gum nanofibers with different mass ratios

[0144] Figure 4 The morphology and diameter distribution of electrospun nanofibers of PEO / GG with different mass ratios are shown. Electrospun nanofibers prepared from spinning solutions with PEO / GG = 10:0 and PEO / GG = 9:1 were uniform, smooth, and free of beading. When the PEO / GG mass ratio increased from 8:2 to 6:4, the nanofibers became less uniform and showed an increase in beading. Furthermore, the diameter of the PEO / GG nanofibers gradually decreased, with average diameters of (234.24 ± 30.79), (233.36 ± 43.85), (204.24 ± 27.61), and (181.86 ± 24.70) nm, respectively. This indicates that as the viscosity of the PEO / GG spinning solution increased, the diameter of the PEO / GG electrospun nanofibers decreased.

[0145] 3.2.3 Infrared Spectral Analysis of Polyethylene Oxide / Gellan Gum Nanofibers with Different Mass Ratios

[0146] ATR-FTIR spectra of PEO powder, GG powder and PEO / GG nanofiber membranes with different mass ratios are shown in Figure 5 The ATR-FTIR spectra of PEO / GG nanofibers all showed characteristic absorption peaks similar to those of PEO powder. Compared with PEO and GG powder, the CH vibration peak of PEO / GG nanofibers increased from 2877 cm to 3047 cm with the increase of GG ratio. -1 Redshift to 2882 cm -1 This indicates that during the electrospinning process, intermolecular hydrogen bonds were formed between the methylene groups (-CH2-) of PEO and the hydroxyl groups (-OH) and carboxyl groups (-COOH) on the GG molecular chain, and the intermolecular interactions were enhanced. In addition, a 3303 cm-1 molecule belonging only to GG was observed in the PEO / GG nanofibers. -1 The characteristic peaks of PEO / GG nanofibers were slightly blue-shifted, which also proved the existence of GG in PEO / GG nanofibers.

[0147] 2.2.4 X-ray diffraction analysis of polyethylene oxide / gellan gum nanofibers with different mass ratios

[0148] The XRD patterns of PEO powder, GG powder and PEO / GG nanofibers with different mass ratios are shown in Figure 2. Figure 6As shown. PEO powder shows strong diffraction peaks at 23.62° and 19.49°. Pure PEO nanofibers show diffraction peaks at 23.50° and 19.25°, with a slight shift in peak position and changes in intensity. The XRD pattern of GG shows broad and diffuse diffraction peaks without obvious sharp peaks. For PEO / GG nanofibers, the diffraction peak intensity at 23.62° and 19.49° weakens with the increase of the GG ratio. This proves that in PEO / GG nanofibers, PEO and GG have good compatibility and enhanced intermolecular interaction between the two.

[0149] 2.2.5 Thermogravimetric analysis of polyethylene oxide / gellan gum nanofibers with different mass ratios

[0150] like Figure 7 As shown in Figure A, GG powder undergoes thermal degradation when heated above 222.37°C, and there is no melting phenomenon during decomposition. TGA / DTG analysis shows that the degradation of GG powder occurs in two steps, with mass losses of 71.39% and 9.47%, respectively. The decomposition process of PEO powder is only one step, with a mass loss of 96.95%. The decomposition temperature of PEO powder is 346.19°C, which is higher than that of GG, and the decomposition end temperature is 429.99°C. Figure 7 As shown in Figure B, the maximum degradation temperature of pure PEO nanofibers is 401.34°C. In comparison, the maximum degradation temperatures of PEO / GG=9:1, PEO / GG=8:2, and PEO / GG=7:3 nanofibers are 409.78°C, 411.85°C, and 413.10°C, respectively, indicating that the increase in the GG ratio improves the thermal stability of PEO / GG nanofibers.

[0151] The increase in the maximum degradation temperature indicates the existence of intermolecular hydrogen bonding interactions between PEO and GG.

[0152] 2.2.6 Differential Scanning Calorimetry Analysis of Polyethylene Oxide / Gellan Gum Nanofibers with Different Mass Ratios

[0153] Figure 8DSC curves of PEO powder, GG powder, and PEO / GG nanofibers with different mass ratios are shown. For PEO powder, an endothermic peak is observed at 69.81°C, which represents the decomposition temperature of PEO powder. The decomposition temperature of GG powder is 135.57°C. The decomposition temperatures of nanofibers with PEO / GG = 10:0, PEO / GG = 9:1, PEO / GG = 8:2, and PEO / GG = 7:3 are 67.43°C, 68.93°C, 64.79°C, and 64.38°C, respectively. As the GG ratio in the PEO / GG nanofibers increases, the endothermic peak of PEO shifts toward lower temperatures, indicating that GG hinders PEO crystallization during the electrospinning process, which is consistent with the XRD results in "2.2.4."

[0154] Based on the above, it can be seen that the optimal mass ratio of polyethylene oxide solution to gellan gum solution is 9:1.

[0155] 2.3 Effect of carvacrol addition on electrospun nanofibers

[0156] 2.3.1 Effect of carvacrol addition on spinning solution properties

[0157] As shown in Table 4, the pH value of the PEO / GG-CAR0 spinning solution was the highest. As the amount of CAR added increased, the pH of the PEO / GG-CAR spinning solution decreased from 7.85±0.01 to 7.25±0.01. The conductivity of the PEO / GG-CAR spinning solution also showed a downward trend, with no significant difference in conductivity between the spinning solutions containing 4% and 5% CAR. Figure 9 A in Figure 1 shows that all PEO / GG-CAR spinning solutions behave as typical non-Newtonian fluids. -1 to 100s -1 The viscosity of the spinning solution without CAR is the highest, while the viscosity of the spinning solution of PEO / GG-CAR5 is the lowest. The relationship between the shear stress and shear rate of the spinning solution of PEO / GG-CAR is shown in Figure 2. Figure 9 The rheological parameters are shown in Table 4. σ0 represents the yield stress of the PEO / GG-CAR spinning solution. The change in K value reflects the decrease in the apparent viscosity of the PEO / GG-CAR spinning solution with increasing CAR concentration. The pseudoplastic fluid properties of the spinning solution were confirmed, and all n values ​​were less than 1. 2 >0.9 indicates that the Herschel-Bulkley model fits the data well.

[0158] Table 4 pH value, conductivity and Herschel-Bulkley model rheological parameters of spinning solutions with different CAR addition amounts

[0159]

[0160]

[0161] 2.3.2 Effect of carvacrol addition on emulsion particle size, Zeta potential, and polydispersity coefficient

[0162] Figure 10 The particle size, Zeta potential and PDI of PEO / GG-CAR emulsion are shown. Figure 10 As shown in Figure A, as the CAR concentration increased from 1% to 5%, the droplet size of the emulsion increased from (127.40±6.59) nm to (347.00±9.40) nm. The particle size of PEO / GG-CAR1 was significantly lower than that of other emulsions (P<0.05). This result shows that the droplet size of the emulsion is greatly affected by the emulsion composition. Figure 10 As shown in Figure B, the Zeta potential of PEO / GG-CAR3 emulsion is the highest, (34.94±1.14) mV, which is significantly higher than that of other emulsions (P<0.05). Figure 10 As shown in Figure C, the PDI of the prepared PEO / GG-CAR emulsions is less than 0.6. When the CAR addition level is 1% and 3%, the PDI values ​​of the PEO / GG-CAR emulsions are lower, at 0.33±0.02 and 0.35±0.03, respectively. This indicates that the prepared PEO / GG-CAR emulsions have good particle size uniformity and dispersion stability.

[0163] 2.3.3 Effect of carvacrol addition on the emulsion microstructure

[0164] The microstructure and appearance distribution of PEO / GG-CAR emulsions with different CAR addition amounts are shown in Figure 2. Figure 11 As shown. As the amount of CAR added increases from 1% to 5%, the droplet size of the emulsion gradually increases, which is consistent with the particle size measurement results in "2.3.2". Among them, the emulsion droplet size prepared by PEO / GG-CAR1 is the smallest, and there is an obvious phenomenon of emulsion droplet aggregation. The PEO / GG-CAR3 emulsion droplets show good dispersibility, a narrow droplet size distribution and no obvious aggregation and flocculation phenomenon, indicating that it has excellent stability and uniformity. The PEO / GG-CAR5 emulsion droplets show a relatively large droplet size, there is a phenomenon of small droplet aggregation, and the emulsion droplet size is uneven. And according to Figure 11 From the appearance of the F emulsion, it can be seen that the PEO / GG-CAR emulsions with different CAR addition amounts have no stratification phenomenon and all form relatively stable emulsions.

[0165] 2.3.4 Effect of carvacrol addition on the morphology of electrospun nanofibers

[0166] The PEO / GG-CAR5 spinning solution could not form nanofibers during the electrospinning process and was therefore not included in this example. Figure 12 As shown, the average diameter of the PEO / GG-CAR0 nanofibers was (354.60 ± 73.19) nm. As the CAR addition increased from 1% to 4%, the diameters of the electrospun nanofibers decreased to (237.98 ± 37.57) nm, (210.98 ± 49.78) nm, (122.74 ± 23.92) nm, and (88.98 ± 28.25) nm, respectively. The average diameter of the PEO / GG-CAR nanofibers gradually decreased, consistent with the changing trend of the solution viscosity. Furthermore, the frequency of beading increased with further increases in the CAR addition. The volume of the beading also increased with increasing CAR addition.

[0167] 2.3.5 Effect of carvacrol addition on the core-shell structure of electrospun nanofibers

[0168] The core-shell structure of PEO / GG-CAR emulsion electrospun nanofibers was observed using TEM. Figure 13 As shown, a distinct boundary between the outer bright region and the inner dark region reveals the difference in electron transport capabilities between the core and shell materials of the PEO / GG-CAR emulsion electrospun nanofibers. The PEO / GG-CAR emulsion electrospun nanofibers contain two types of oil droplets: uniform, axially aligned oil droplets in the smooth electrospun nanofibers and large oil droplets within the beaded electrospun nanofibers. When the CAR addition level is low, uniform dispersion of oil droplets is observed within the smooth electrospun nanofibers.

[0169] 2.3.6 Effect of carvacrol addition on the infrared spectrum of electrospun nanofibers

[0170] ATR-FTIR spectra of electrospun nanofibers and CAR with different CAR addition amounts are shown in Figure 14 CAR at 3344cm -1 and 2958cm -1 The characteristic absorption peaks at 1620 cm-1 correspond to the stretching vibrations of OH and CH, respectively. -1 and 1420cm -1 The absorption peak at 866 cm is the CC stretch of the CAR aromatic ring. -1 and 813cm -1 The absorption peak at 400 cm is the C=C stretching vibration of the aromatic ring. -1 and 1600cm -1Many characteristic absorption peaks of CAR were also found. However, these characteristic peaks disappeared in PEO / GG-CAR nanofibers with different CAR addition amounts. This shows that CAR is compatible with the PEO / GG matrix and there are intermolecular or intramolecular interactions. The ATR-FTIR spectrum of PEO / GG-CAR nanofibers showed absorption peaks similar to those of PEO / GG nanofibers, but the peak intensity was slightly reduced, which showed that the addition of CAR did not change the overall structure of the PEO / GG composite nanofiber material. At the same time, the 3344 cm-1 of PEO / GG-CAR nanofibers with a CAR addition of 1%-4% -1 A new absorption peak appeared near the ions, which corresponded to the OH oscillation of the CAR molecules and became stronger with the increase of CAR addition.

[0171] 2.3.7 Effect of carvacrol addition on X-ray diffraction of electrospun nanofibers

[0172] like Figure 15 As shown, XRD spectra demonstrate the crystalline properties of PEO / GG-CAR electrospun nanofibers with varying CAR additions. As shown in the figure, the CAR-added PEO / GG-CAR electrospun nanofibers exhibit similar characteristic diffraction peaks compared to the electrospun nanofibers without CAR addition. This indicates that CAR is uniformly dispersed within the PEO / GG electrospun nanofibers and lacks a crystalline structure. The intensity of the characteristic diffraction peaks increases with increasing CAR addition, suggesting the possible formation of hydrogen bonds between CAR, PEO, and GG, leading to increased intermolecular forces.

[0173] 2.3.8 Effect of carvacrol addition on the thermogravimetric properties of electrospun nanofibers

[0174] like Figure 16 As shown in the figure, the first stage ends at around 100°C due to water evaporation. The PEO / GG-CAR nanofibers show almost no weight loss. The temperature range of the second stage is 100 to 300°C. The third stage of thermal degradation occurs between 300°C and 500°C and is the main weight loss zone. With the increase of CAR addition, the maximum degradation temperature increases from 404.34°C to 409.41°C, 408.86°C, 408.31°C, and 409.04°C, respectively, indicating that the addition of CAR improves the thermal stability of PEO / GG-CAR nanofibers.

[0175] 2.3.9 Effect of carvacrol addition on differential scanning calorimetry of electrospun nanofibers

[0176] like Figure 17As shown, the decomposition temperature of PEO / GG-CAR0 electrospun nanofibers is 62.37°C, while the decomposition temperatures of PEO / GG-CAR1, PEO / GG-CAR2, PEO / GG-CAR3, and PEO / GG-CAR4 are 58.47°C, 61.31°C, 63.35°C, and 64.36°C, respectively. This may be because a small amount of CAR interferes with the molecular chain arrangement of PEO and GG, reducing crystallinity and leading to a decrease in decomposition temperature. As the CAR addition increases to above 3%, new intermolecular interactions or crystalline structures may form, increasing the overall crystallinity of the PEO / GG-CAR nanofibers and causing an increase in their decomposition temperature.

[0177] 2.3.10 Effect of carvacrol addition on the water contact angle of electrospun nanofibers

[0178] like Figure 18 As shown in the figure, for the electrospun nanofiber membranes with different CAR addition amounts, the water contact angles of PEO / GG-CAR0, PEO / GG-CAR1, PEO / GG-CAR2, PEO / GG-CAR3, and PEO / GG-CAR4 were (18.69±0.68)°, (21.46±1.33)°, (32.84±1.66)°, (43.63±2.18)°, and (54.09±3.34)°, respectively. The PEO / GG-CAR4 electrospun nanofiber membrane had the highest water contact angle, significantly higher than the other groups (P<0.05). Compared with the PEO / GG-CAR0 electrospun nanofiber membrane, the water contact angle of the electrospun nanofiber membrane gradually increased with increasing CAR addition, indicating that its surface hydrophobicity was effectively improved. The results showed that due to the hydrophobicity of CAR itself, its addition to PEO / GG may partially change the hydrophilicity of the matrix, resulting in a decrease in the hydrophilicity and an increase in the hydrophobicity of the electrospun nanofiber membrane.

[0179] 2.3.11 Effect of carvacrol addition on the mechanical properties of electrospun nanofibers

[0180] Figure 19 Figure A shows the stress-strain curves of the PEO / GG-CAR nanofiber membrane. Among these samples, the stress increase of the PEO / GG-CAR3 nanofiber membrane is the largest. Figure 19As shown in Figure B, the elongation at break and tensile strength of the PEO / GG-CAR0 nanofiber membrane were 57.66% and 0.39 MPa, respectively. After adding 3% CAR, the elongation at break and tensile strength of the nanofiber membrane increased significantly to 109.94% and 0.87 MPa, respectively (P < 0.05). When the CAR addition level increased to 4%, both the elongation at break and the tensile strength of the nanofiber membrane decreased significantly. The mechanical properties of the PEO / GG-CAR nanofiber membrane initially increased and then decreased, which was closely related to the amount of CAR added. When the CAR addition level increased from 1% to 3%, molecular interactions between CAR and the membrane matrix occurred, forming hydrogen bonds. However, as the CAR addition level continued to increase, excessive CAR disrupted the crosslinking network, leading to a decrease in mechanical properties. These results demonstrate that the PEO / GG-CAR nanofiber membrane exhibits excellent tensile strength and flexibility, suggesting potential applications for this material in food packaging.

[0181] 2.3.12 Effect of carvacrol addition on the antioxidant properties of electrospun nanofibers

[0182] The results are as follows Figure 20 As shown in the results, the free radical scavenging ability of PEO / GG-CAR nanofiber membrane was significantly enhanced with the increase of CAR addition (P < 0.05). The DPPH free radical scavenging rates of PEO / GG-CAR nanofibers with CAR addition of 0%, 1%, 2%, 3% and 4% were (11.83 ± 0.49)%, (41.25 ± 1.04)%, (45.45 ± 0.75)%, (53.37 ± 0.45)% and (59.58 ± 0.51)%, respectively. + The free radical scavenging rates were (15.27±0.78)%, (48.72±0.73)%, (51.99±1.03)%, (64.44±1.14)% and (68.92±1.17)%, respectively. In this experiment, the free radical scavenging rates of PEO / GG-CAR4 nanofiber film on DPPH and ABTS were significantly higher than those of GG-CAR4 nanofiber film on DPPH and ABTS. + The free radicals have good scavenging ability, which indicates its potential application value in active food packaging.

[0183] Example 2 Determination of antibacterial properties of electrospun nanofibers with different carvacrol addition amounts

[0184] 1 Preparation of electrospun nanofibers with different carvacrol addition amounts

[0185] Weighed PEO powder was added to 20 mL of deionized water and stirred continuously at 60°C using a magnetic stirrer for 4 hours to prepare 7% (w / v) PEO spinning solutions. After the solutions were thoroughly mixed and allowed to stand to eliminate bubbles, the PEO spinning solutions were obtained.

[0186] The electrospinning process was performed in a horizontal mode using a high-voltage power supply, syringe pusher, and receiver plate. PEO spinning solutions of varying concentrations were injected into a 5 mL syringe fitted with a 21G needle (0.51 mm inner diameter). The electrospinning process was performed under the following parameters: a flow rate of 0.48 mL / h, a forward voltage of 15 kV, and a tip-to-receiver plate distance of 15 cm. Electrospun nanofiber membranes were prepared under ambient conditions of 25 ± 1°C and 50 ± 1% relative humidity.

[0187] Preparation of PEO / gellan gum (GG) blend spinning solution: 7% (w / v) PEO spinning solution and 1.5% (w / v) GG solution were mixed in a mass ratio of 9:1, with a total mass of 20 g of the mixed solution, and magnetic stirring was performed at 60°C for 1 h.

[0188] Carvacrol (CAR) was added to the PEO and GG solutions at concentrations of 1%, 2%, 3%, and 4% (w / w) relative to the total mass of the two solutions. Simultaneously, 2% (w / w) Tween 80 was added to the spinning solution as an emulsifier. The electrospinning solution was magnetically stirred at room temperature for 5 hours to ensure complete dissolution. The mixture was then sheared at 10,000 rpm for 5 minutes using a high-speed shear to prepare an oil-in-water emulsion. The spinning solutions with different CAR concentrations were labeled PEO / GG-CAR1, PEO / GG-CAR2, PEO / GG-CAR3, and PEO / GG-CAR4.

[0189] 2 Determination of antibacterial properties of electrospun nanofibers with different carvacrol addition amounts

[0190] Prepare a mixture containing approximately 1×10 6 A suspension of Staphylococcus aureus CMCC 29213 (S. aureus CMCC29213) or Escherichia coli ATCC 25922 (E. coli ATCC 25922) was prepared. After the agar solidified, 100 μL of the electrospun nanofiber solution was added to a Petri dish via an Oxford cup (8.0 mm outer diameter, 6.0 mm inner diameter, 10.0 mm height) and incubated at 37°C for 24 hours. Finally, the diameter of the inhibition zone was measured using a vernier caliper. Bacteria treated with PBS served as a control.

[0191] 20 mg of electrospun nanofiber membranes with different carvacrol addition amounts were placed in a 1×10 6The cells were then incubated at 37°C for 24 hours in a bacterial suspension containing 100 CFU / mL of culture medium. The suspension was centrifuged at 3700 × g at 4°C for 3 minutes to remove the supernatant. The bacteria were then fixed with 2.5% glutaraldehyde at 4°C for at least 12 hours. The samples were then dehydrated with 50%, 70%, 90%, and 100% ethanol for 10 minutes each, followed by freeze-drying for 24 hours. Finally, the samples were examined using a scanning electron microscope.

[0192] In order to study the ability of electrospun nanofiber membranes with different carvacrol addition amounts to inhibit biofilm formation, the following experiment was conducted: 5 mg of electrospun nanofiber membranes were sterilized on each side by ultraviolet light for 15 min and then placed in a 48-well polystyrene plate. 500 μL of 1×10 6 CFU / mL of S.aureus CMCC 29213 in MHB liquid medium and cultured at a constant temperature of 37°C. The effect of electrospun nanofiber membrane on Staphylococcus aureus biofilm formation was quantitatively analyzed by crystal violet detection after 24 hours. The bacterial solution in each well was removed, and then washed three times with PBS buffer, and then stained with 0.1% (w / v) crystal violet for 30 minutes. The stained biofilm was dissolved in 33% (v / v) glacial acetic acid, and the absorbance value was measured at 595nm using a UV spectrophotometer for quantitative analysis. According to the above biofilm culture process, the biofilm morphology was evaluated using the Calcein-AM / PI staining method. The biofilm was mixed with 1mL of dye solution, cultured at 37°C for 10 minutes, and finally observed using a laser confocal microscope.

[0193] 3 Effect of carvacrol addition on the antibacterial properties of electrospun nanofibers

[0194] The inhibition zone image of PEO / GG-CAR active electrospun nanofiber membrane is shown in Figure 2. Figure 21 As shown. PEO / GG-CAR nanofibers exhibited inhibitory effects on both Staphylococcus aureus and Escherichia coli, and the diameter of the inhibition zone gradually expanded with increasing CAR addition. The diameters of the inhibition zones against Escherichia coli and S. aureus for PEO / GG-CAR nanofibers with different CAR additions are shown in Table 5. The diameter of the inhibition zone for E. coli increased from (17.42±0.36) mm to (18.46±0.25) mm, and the diameter of the inhibition zone for S. aureus increased from (16.96±0.63) mm to (18.92±0.23) mm. The larger the amount of CAR added, the larger the diameter of the inhibition zone, and the higher the corresponding inhibition rate. The results of the inhibition zone test showed that PEO / GG nanofibers with different CAR additions exhibited good antibacterial activity against E. coli and S. aureus, with PEO / GG-CAR4 showing the strongest inhibitory ability. This indicates that CAR retains good antibacterial biological activity after electrospinning encapsulation.

[0195] Table 5 Inhibition zone diameters of electrospun nanofibers with different CAR addition amounts

[0196]

[0197]

[0198] like Figure 22 As shown, the Staphylococcus aureus in the control group was spherical, intact, and had a smooth surface. After treatment with the PEO / GG-CAR4 nanofiber membrane, most of the test bacteria died, and their morphology also changed (the bacteria became distorted, their cell walls damaged, and the previously intact and plump bacterial cells collapsed and shrunken, with a large amount of intracellular contents leaking out). The prepared PEO / GG-CAR4 nanofiber membrane exhibited excellent antibacterial effects, indicating that this material may have potential application value in the field of food packaging.

[0199] like Figure 23 As shown in Figure A, with the increase of CAR addition in the nanofibers, when the biofilm stained with crystal violet was dissolved with glacial acetic acid, the color of the solution gradually became lighter, indicating that the amount of biofilm formed was getting smaller and smaller. The inhibition rate of different addition amounts of CAR on the formation of Staphylococcus aureus biofilm on PEO / GG electrospun nanofiber membranes is shown in Figure 4. Figure 23 As shown in Figure B. As the addition amount of CAR increased from 0% to 4%, the inhibition rate of Staphylococcus aureus biofilm formation increased significantly from (4.73±0.41)% to (62.49±0.45)% (P<0.05). This result shows that CAR can effectively inhibit the formation of Staphylococcus aureus biofilm, and the degree of inhibition is concentration-related. Figure 23 As shown in Figure (C), green fluorescence in the confocal laser scanning microscope image indicates the number of viable biofilm cells after nanofiber treatment, while dead biofilm cells emit red fluorescence. Compared to the control group, increasing the CAR concentration from 0% to 4% gradually reduced biofilm formation. The control group exhibited a higher population density of S. aureus, with most cell membranes intact, and green fluorescence occupying the largest area in the field of view. As indicated by the red fluorescence, the PEO / GG-CAR nanofiber membrane exhibited strong anti-biofilm activity, effectively inactivating the majority of S. aureus biofilm cells.

[0200] Example 3 Effect of carvacrol antibacterial nanofiber membrane on strawberry preservation

[0201] 1 Preparation of electrospun nanofibers with different carvacrol addition amounts

[0202] Electrospun nanofibers with different carvacrol addition amounts were prepared according to the method of Example 2

[0203] 2. Strawberry sample processing

[0204] Fresh strawberries of similar maturity, size, and color were randomly divided into four groups: a blank control (untreated), a commercially available absorbent pad (CAAM)-treated group, a PEO / GG-CAR0-treated group, and a PEO / GG-CAR4-treated group, with six strawberries in each group. Either a commercially available absorbent pad or nanofiber membrane was laid flat on the bottom of a fresh-keeping container, with the strawberries placed directly on the surface. All strawberries in all treatment groups were stored at room temperature for 8 days, with the container sealed during storage. Photographs were taken every 48 hours during storage to observe any signs of deterioration.

[0205] 3 Determination of main preservation effect indicators of strawberries

[0206] (1) Determination of weight loss rate

[0207] Three fruits were selected from each group as test samples and numbered. The samples were weighed one by one using an electronic balance with an accuracy of 0.01 g. The initial weight was recorded and the average within the group was calculated. The weight loss rate was calculated using the following formula:

[0208]

[0209] Where M0 represents the mass of the sample before storage (g); M1 represents the mass of the sample after storage (g).

[0210] (2) Determination of hardness

[0211] First, cut the strawberry along its longitudinal axis and place it securely on the stage with the cut surface facing downward. A P / 50 cylindrical probe was used, with a trigger threshold set at 5g. During the test, the probe performed pre-compression, compression, and return motions at a constant speed of 1.00mm / s, with the final compression deformation set at 30% of the sample height. Each sample was measured three times in parallel, and the results are presented as the average.

[0212] (3) Determination of pH value

[0213] Accurately weigh 3.0 g of strawberry sample and add 27 mL of deionized water. Stir magnetically at 600 rpm for 10 minutes at room temperature. After the sample is thoroughly mixed, measure the pH of the strawberry suspension using a calibrated pH meter. Perform three replicate measurements for each sample, and present the results as the average.

[0214] (4) Determination of titratable acid content

[0215] Accurately weigh 10.0g of strawberry sample, fully crush it with a high-speed shearing machine, and quantitatively transfer it to a 50mL volumetric flask. Make up to volume with deionized water and oscillate to prepare the test solution. Then transfer 10.00mL of the test solution to a 150mL conical flask and add 3 drops of 1% phenolphthalein indicator prepared with 95% ethanol as solvent. Use a calibrated 0.1mol / L sodium hydroxide standard solution for titration. When the test solution turns light pink and lasts for not less than 30s, it is determined to be the titration end point, and the consumption of sodium hydroxide standard solution is accurately recorded. In order to eliminate systematic errors, a blank control test is carried out simultaneously during the experiment, replacing the sample solution with deionized water and maintaining the same operating conditions. The titratable acid content is calculated according to the following formula:

[0216]

[0217] Wherein, C represents the concentration of sodium hydroxide standard solution (mol / L); V represents the volume of sodium hydroxide consumed by the sample solution (mL); V0 represents the volume of sodium hydroxide consumed by the blank control group (mL); V1 represents the total volume of the sample solution (mL); V2 represents the volume of the measured sample solution (mL); f represents the conversion coefficient 0.064; and m represents the sample mass (g).

[0218] (5) Determination of color difference

[0219] For each strawberry sample, the lightness (L*), redness (a*), and yellowness (b*) values ​​were measured using a colorimeter. The total color change (ΔE) was calculated as follows:

[0220]

[0221] (6) Determination of microbial colony structure

[0222] Shanghai Paisonno Biotechnology Co., Ltd. was selected to analyze the microbial colony structure of strawberry DNA samples. Using Illumina high-throughput sequencing technology, a systematic analysis was conducted on the differences in microbial community composition of strawberry samples after eight days of storage under different treatments at the five taxonomic levels of microbial taxonomy: phylum, class, order, family, and genus.

[0223] 3 Statistical analysis

[0224] All experiments were repeated three times, and data are presented as mean ± standard deviation. Data were analyzed using SPSS 25.0 statistical software. One-way analysis of variance (ANOVA) was used for intergroup comparisons, and Turkey's test was used for multiple comparisons. P < 0.05 indicated a significant difference. Data visualization was created using Origin 2021 software. Significant differences in the charts are indicated by different letters.

[0225] 4 Effect of carvacrol antibacterial nanofiber membrane on strawberry preservation

[0226] 4.1 Effects of different treatments on strawberry surface morphology

[0227] like Figure 24 As shown, the blank control group, lacking protective measures, experienced the most pronounced dehydration, shrinkage, enzymatic browning, and mold formation during storage. Localized mold was observed on the surface of the samples on the fourth day. As storage extended to the eighth day, the severity of strawberry decay intensified, with widespread tissue softening and a strong putrid odor. The CAAM treatment delayed browning and mold formation, but likely due to insufficient air permeability, the fruit softened and juice oozed, leading to the onset of decay and deterioration on the sixth day. The PEO / GG-CAR0 treatment effectively reduced water loss and oxygen exchange, significantly delaying shrinkage, but its antibacterial effect was limited in the later stages. After eight days of storage, all test samples, except the PEO / GG-CAR4 treatment, displayed clear signs of decay. Although the PEO / GG-CAR4-treated strawberries showed a slight darkening of color and a slight softening of texture, their surface morphology remained excellent, indicating high edible value.

[0228] 4.2 Effects of different treatments on strawberry weight loss rate

[0229] like Figure 25 As shown, different treatments significantly affected the weight loss of strawberries during postharvest storage (P < 0.05). The weight loss rates of all experimental groups showed a significant upward trend with prolonged storage time (P < 0.05). The blank control group maintained the highest weight loss rate throughout the entire experimental period, significantly higher than that of the other treatment groups (P < 0.05). This confirms that untreated strawberries have poor storability. The weight loss rates of the CAAM and PEO / GG-CAR0 treatments were similar. However, the PEO / GG-CAR4 treatment group exhibited the best water retention, with a weight loss rate of only (6.85 ± 0.04)% on day 8, which was 2.45%, 0.75%, and 1.16% lower than those of the other three groups, respectively, effectively reducing the weight loss rate of strawberries. The PEO / GG-CAR4 electrospun nanofiber membrane not only effectively reduces water evaporation from strawberries but also may extend the shelf life of strawberries by regulating respiratory metabolic pathways.

[0230] 4.3 Effects of different treatments on strawberry firmness

[0231] like Figure 26 As shown in the figure, within 8 days of storage, the hardness of all groups of samples decreased sharply. The hardness of strawberries in the blank control group decreased from the initial (3.05±0.18)N to (0.36±0.06)N. Figure 26 The sharp decline in strawberry firmness in the blank control group may be due to the rapid loss of water and the degradation of pectin in the strawberry cell walls, which deprives the tissue structure of support. The PEO / GG-CAR4 treatment group demonstrated the best firmness retention, significantly higher than the other three groups (P < 0.05). The PEO / GG-CAR4 treatment group still maintained 54.46% of its initial firmness after 8 days of storage, significantly better than the other groups (P < 0.05). This mechanism of action may be that the increased surface humidity of the strawberry samples facilitates the sustained release of CAR's active ingredients. In addition, CAR may inhibit the activity of certain enzymes in strawberries, delaying pectin degradation to maintain the structural integrity of the cell wall.

[0232] 4.4 Effects of different treatments on strawberry acidity

[0233] like Figure 27 and Figure 28 As shown in the results, after 8 days of storage, the pH of the PEO / GG-CAR4-treated group was 4.30 ± 0.04, 0.33% lower than that of the control group. Furthermore, the titratable acid content of the treated group was maintained at (0.65 ± 0.03)%, an increase of 0.19% compared to the blank control group. These results indicate that the PEO / GG-CAR4-treated group effectively maintains the acidity of strawberries. CAR can reduce the decomposition rate of organic acids by regulating respiratory metabolic pathways. Furthermore, CAR can effectively control the microbial population, thereby reducing the production of acidic substances due to microbial metabolism.

[0234] 4.5 Effects of different treatments on strawberry color difference

[0235] like Figure 29 As shown in the results, after 8 days of storage, the ΔE values ​​of strawberries in all groups showed a downward trend. The strawberries in the blank control group showed obvious browning, with their ΔE value decreasing from the initial 51.48 to 29.67, indicating that the color of the fruit surface had significantly deepened. In contrast, the experimental group treated with PEO / GG-CAR4 electrospun nanofiber membrane showed the best color protection effect, with its ΔE value decreasing from 55.16 to 45.40, a significantly lower decrease than that of the blank control group (P < 0.05). This shows that the PEO / GG-CAR4 electrospun nanofiber membrane material can effectively prevent the color deterioration of strawberries during storage, thereby maintaining the appearance quality of the fruit.

[0236] 4.6 Analysis of microbial colony structure of strawberries under different treatments

[0237] 4.6.1 Alpha Diversity Analysis

[0238] like Figure 30As shown in the figure. The Chao1 index, Simpson index, Shannon index, and observed_species index of the blank control group were all the highest, indicating that the bacterial richness and species diversity of the strawberry samples in the blank control group were higher. The values ​​of the four indices in the CAAM treatment group were all lower than those in the blank control group, indicating that it can reduce the bacterial richness and species diversity of strawberries. In addition, the Chao1 index and observed_species index of the PEO / GG-CAR4 treatment group were both the lowest, indicating that the electrospun nanofiber membrane encapsulating CAR can effectively reduce the bacterial richness and species number of strawberries.

[0239] 4.6.2 Species composition and difference analysis

[0240] (1) Species composition and difference analysis based on phylum level

[0241] like Figure 31 As shown, the bacterial composition of strawberries treated with different methods differed significantly after 8 days of storage. Five clearly classified bacterial phyla were identified in all samples, along with some unannotated microbial groups, primarily Firmicutes, Proteobacteria, Actinobacteria, Bdellovibrio, and Gemmatimonadota. The study found that compared to the blank control, the relative abundance of Firmicutes was highest in the strawberry samples treated with different methods, ranging from 67.94% to 97.75%. Compared to the blank control, the other three treated strawberries showed an increase in Firmicutes and a decrease in Proteobacteria.

[0242] (2) Species composition and difference analysis based on genus level

[0243] like Figure 32As shown, the bacterial diversity of strawberries after 8 days of storage is relatively high, mainly including Leuconostoc, Gluconobacter, Pantoea, Weissella, Rummeliibacillus and Sphingomonas. From the blank control group, it can be seen that the relative abundance of Weissella and Gluconobacter is significantly higher than that of other genera, accounting for 14.49% and 69.08% respectively. Most of the genera in the treated strawberries are Leuconostoc. Leuconostoc is generally considered to be a safe genus. The organic acids it produces can inhibit the growth of pathogens and spoilage bacteria, extending the shelf life of strawberries, but its excessive growth may affect the flavor and taste of strawberries. Through the above analysis, it was found that the presence of typical foodborne pathogens such as Listeria monocytogenes and Salmonella was not found within the detection range of this embodiment based on 16SrRNA gene sequencing. However, at least one bacterial genus with potential pathogenic risk was identified in all strawberry samples, and multiple microbial groups closely related to strawberry spoilage were detected.

[0244] 4.6.3 Principal Component Analysis

[0245] like Figure 33 As shown in the figure, the PCA results are plotted with the first principal component (PC1) on the horizontal axis and the second principal component (PC2) on the vertical axis. PC1 has a higher variance contribution than PC2, indicating a stronger ability to explain data variation. The PEO / GG-CAR4-treated group and the blank control group were located far apart on both PC1 and PC2, indicating differences in the colony structure between the two groups. The PEO / GG-CAR4-treated group and the CAAM-treated group were closest to each other on PC1, indicating that the PEO / GG-CAR4 electrospun nanofiber membrane has similar preservation effects on strawberries as commercially available absorbent pads, suggesting potential market applications. Combined with the PCA analysis results, it can be seen that the electrospun nanofiber membrane with the addition of CAR can effectively regulate the microbial community of strawberries, thereby exerting a preservative and fresh-keeping effect.

[0246] Example 4 Inhibitory Effect of Electrospun Nanofibers on Tumor Cells (Anticancerous Activity)

[0247] 1 Preparation of electrospun nanofibers with different carvacrol addition amounts

[0248] Electrospun nanofibers with different carvacrol addition amounts (PEO-GG fiber membranes with different CAR concentrations) were prepared according to the method of Example 2.

[0249] 2 Methods

[0250] The anticancer activity of PEO-GG fiber membranes containing different concentrations of CAR was evaluated using human colorectal adenocarcinoma cells Caco-2. Human colorectal adenocarcinoma cells Caco-2 were cultured in Dulbecco's modified Eagle's medium containing 10% fetal bovine serum and 1% penicillin / streptomycin (the specific components of Dulbecco's modified Eagle's medium contain 4.5g / LD-glucose, 584mg / LL-glutamine and 110mg / L sodium pyruvate) and placed in a 37°C, 5% CO2 incubator. When the cells were 80% full of the culture flask, 0.25% trypsin-EDTA solution was used to separate the cells. The cells were seeded in a 96-well plate at a density of 10,000 cells / well and incubated for 24 hours. After cell attachment, the original culture medium was replaced with 200 μL of fresh culture medium (Dulbecco's modified Eagle's medium containing 10% fetal bovine serum and 1% penicillin / streptomycin) containing PEO-GG fiber membranes with different concentrations of CAR (1000 μg / mL) and incubated for 24 hours. The culture medium was then discarded, and 100 μL of 10% CCK-8 culture medium solution was added to each well, followed by incubation for 30 minutes in the dark. Finally, the absorbance at 450 nm was recorded using a microplate reader, and the cell inhibition rate was calculated.

[0251] 3 Results

[0252] The inhibition rate of PEO-GG nanofiber membranes containing different concentrations of CAR on Caco-2 cells is as follows Figure 34 As shown. Compared with the nanofiber membrane without CAR, the Caco-2 cell inhibition rate of the nanofiber membrane with CAR was significantly increased (P<0.05). With the increase of CAR addition, the inhibition rate of PEO-GG-CAR nanofibers on Caco-2 cells increased. Among them, there was no significant difference in the cell inhibition rate between PEO-GG-CAR1 and PEO-GG-CAR2 fiber membranes, and there was no significant difference in the cell inhibition rate between PEO-GG-CAR3 and PEO-GG-CAR4 fiber membranes (P>0.05). However, the cell inhibition rate of PEO-GG-CAR4 fiber membrane was significantly higher than that of PEO-GG-CAR0, PEO-GG-CAR1 and PEO-GG-CAR2 (P<0.05), and was 4.22 times that of PEO-GG-CAR0 fiber membrane.

[0253] Based on the above examples, we can draw the following conclusions:

[0254] (1) As the concentration of PEO spinning solution increased from 5% to 8%, the pH value showed an upward trend and the conductivity increased significantly (P<0.05). As the concentration of PEO spinning solution increased, the diameter of electrospun nanofibers increased from (118.82±27.85) nm to (312.12±46.15) nm, and the morphology of the nanofibers gradually improved. At low concentration (5%), the solution viscosity was too low, resulting in beading and fiber breakage; while at high concentrations (7% and 8%), the increased solution viscosity suppressed jet splitting, forming fibers with uniform morphology. Considering the fiber morphology, diameter distribution and spinning efficiency, a PEO solution with a concentration of 7% was selected, which took into account both fiber integrity and spinnability and was suitable for subsequent studies.

[0255] (2) Compared with pure PEO solution, the pH value of PEO / GG blend spinning solution with different mass ratios was significantly reduced (P<0.05). As the proportion of GG in the PEO / GG spinning solution increased, the conductivity of the spinning solution increased significantly (P<0.05) and the viscosity gradually increased. When the PEO / GG mass ratio increased from 9:1 to 6:4, the diameter of the prepared nanofibers gradually decreased and the number of beads increased. Attenuated total reflection Fourier transform infrared spectroscopy and X-ray diffraction showed that there was an intermolecular hydrogen bond interaction between PEO and GG. Thermal performance analysis showed that the addition of GG enhanced the thermal stability of PEO / GG nanofibers.

[0256] (3) With the increase of CAR addition in the spinning solution, the pH value, conductivity and viscosity of the PEO / GG-CAR spinning solution gradually decreased. PEO / GG-CAR emulsions with different CAR additions showed no stratification phenomenon and all formed relatively stable emulsions. As the CAR concentration increased from 1% to 5%, the particle size of the PEO / GG-CAR emulsion gradually increased. The PDI of the prepared PEO / GG-CAR emulsions was less than 0.6. Among them, the Zeta potential of the PEO / GG-CAR3 emulsion was the highest. As the CAR addition increased from 0% to 4%, the diameter of the nanofibers gradually decreased, but a core-shell structure was observed. Attenuated total reflection Fourier transform infrared spectroscopy and X-ray diffraction showed that hydrogen bonds were formed between CAR, PEO and GG, the intermolecular force increased, and CAR was encapsulated into the nanofibers. The addition of CAR improved the thermal stability and water contact angle of the PEO / GG-CAR nanofiber membrane. The elongation at break and tensile strength of PEO / GG-CAR nanofiber membranes increased first and then decreased with the increase of CAR addition. Antioxidant analysis showed that the addition of CAR significantly improved the ABTS resistance of PEO / GG-CAR nanofibers. + and DPPH free radical scavenging ability (P<0.05). In addition, the antibacterial activity of PEO / GG-CAR nanofiber membrane gradually increased with the increase of CAR addition.

[0257] (4) The present invention confirms that the PEO / GG-CAR4 electrospun nanofiber membrane can extend the shelf life of strawberries by 3-4 days and effectively slow down the deterioration of the weight loss rate, hardness, acidity and color of strawberry fruits. Microbial colony structure analysis shows that the PEO / GG-CAR4 treatment group can effectively reduce the bacterial richness and species number of strawberries, inhibit related spoilage bacteria such as Proteobacteria, and promote the relative abundance of anaerobic microorganisms such as Firmicutes. At the genus level, the PEO / GG-CAR4 treatment group is dominated by the genus Leuconostoc. Principal component analysis confirmed that the electrospun nanofiber membrane with the addition of CAR can effectively regulate the microbial community of strawberries, thereby playing a role in preserving and preserving.

[0258] (5) The present invention confirms that PEO / GG-CAR4 electrospun nanofiber membrane can effectively inhibit the growth of cancer cells (human colorectal adenocarcinoma cells Caco-2), ultimately achieving the purpose of experimental treatment of cancer.

[0259] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing polyethylene oxide / gellan gum-carvacrol electrospun nanofibers, characterized in that: The following steps are involved: performing electrostatic spinning treatment on polyethylene oxide to obtain a polyethylene oxide spinning solution; mixing the polyethylene oxide spinning solution and the gellan gum solution to obtain a polyethylene oxide / gellan gum blended spinning solution; After the polyethylene oxide / gellan gum blend spinning solution and carvacrol are mixed, Tween 80 is added, and stirring and shearing are performed to obtain the polyethylene oxide / gellan gum-carvacrol electrospun nanofibers.

2. The preparation method according to claim 1, characterized in that The mass ratio of the polyethylene oxide spinning solution to the gellan gum solution is (6-9):(1-4); The concentration of polyethylene oxide in the polyethylene oxide spinning solution is 5%-8%; The concentration of gellan gum in the gellan gum solution is 1.5%; The amount of carvacrol used is 1%-5% of the mass of the polyethylene oxide / gellan gum blended spinning solution.

3. The preparation method according to claim 2, characterized in that The mass ratio of the polyethylene oxide spinning solution to the gellan gum solution is 9:1; The concentration of polyethylene oxide in the polyethylene oxide spinning solution is 7%; The amount of carvacrol used is 3%-4% of the mass of the polyethylene oxide / gellan gum blended spinning solution.

4. The preparation method according to claim 1, characterized in that The amount of Tween 80 used is 2% of the mass of the mixed solution obtained by mixing the polyethylene oxide / gellan gum blend spinning solution and carvacrol.

5. Polyethylene oxide / gellan gum-carvacrol electrospun nanofibers obtained by the preparation method according to any one of claims 1 to 4.

6. Use of the polyethylene oxide / gellan gum-carvacrol electrospun nanofibers according to claim 5 in any of the following (1) Preparation of antibacterial film; (2) Preparation of antibacterial drugs; (3) preparing a fresh-keeping film; (4) preparing a preservative; (5) Preparation of anti-tumor drugs.

7. The use according to claim 6, characterized in that The pathogenic bacteria targeted by the antimicrobial film or antimicrobial drug include one or more of Staphylococcus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, cluster A type B hemolytic Streptococcus, Streptococcus mutans, Streptococcus sanguis, Actinomyces naeslundii, acid-fast bacteria, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, Veillonella, Candida albicans, Salmonella, Listeria monocytogenes, Pseudomonas aeruginosa, Bacillus cereus, Bacillus stearothermophilus, Clostridium thermosaccharolyticum, Clostridium niger, Clostridium botulinum, Helicobacter pylori, Enterococcus faecalis, toxigenic Bacteroides fragilis and Streptococcus bovis; the Salmonella includes Salmonella typhimurium and / or Salmonella pullorum; the Staphylococcus includes one or more of Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus albus; The tumor includes one or more of colorectal cancer, gastric cancer, cervical cancer, ovarian cancer, breast cancer, thyroid cancer, prostate cancer, pancreatic cancer, glioma, bile duct cancer, liver cancer and lung cancer.

8. An antibacterial film or antibacterial drug, characterized in that: The invention comprises the polyethylene oxide / gellan gum-carvacrol electrospun nanofibers as claimed in claim 5.

9. A fresh-keeping film or preservative, characterized in that: The invention comprises the polyethylene oxide / gellan gum-carvacrol electrospun nanofibers as claimed in claim 5.

10. An anti-tumor drug, characterized in that: The invention comprises the polyethylene oxide / gellan gum-carvacrol electrospun nanofibers as claimed in claim 7.

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