Preparation method and application of slow-release antibacterial fiber film based on Janus structure

Abstract

The application belongs to the field of food packaging and relates to a preparation method of a slow-release antibacterial fiber film based on a Janus structure and application thereof, the preparation method being as follows: taking a chitosan / polylactic acid nanofiber film as a receiving substrate, using a double-needle parallel electrospinning or needleless electrospinning method, electrospinning a positively charged spinning solution A and a negatively charged spinning solution B to obtain an electrospinning fiber film, or taking a petal-shaped nanometer ZnO fiber film as a receiving substrate, using a double-needle parallel electrospinning or needleless electrospinning method, electrospinning a positively charged spinning solution C and a positively charged spinning solution D to obtain an electrospinning fiber film, and subjecting the electrospinning fiber film to post-treatment to obtain a slow-release antibacterial fiber film; and the application is: used for food preservation. The preparation method is simple, the slow-release antibacterial fiber film prepared has high bonding firmness between layers and excellent antibacterial performance, and has a good application prospect in food preservation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food packaging, and relates to a preparation method of a slow-release antibacterial fiber film based on a Janus structure and application thereof. BACKGROUND

[0002] Due to the advantages of low cost, strong plasticity and excellent mechanical properties, petroleum-based plastics and their derived packaging materials are widely used in modern society. However, petroleum is a non-renewable resource, and the resource consumption is serious when a large amount of petroleum-based plastics and their packaging materials are produced. In addition, petroleum-based plastics and their packaging materials have problems such as being difficult to degrade in the natural environment and possibly releasing harmful substances under heating or exposure to specific environments. Therefore, it is necessary to develop environmentally friendly packaging materials that are renewable and biodegradable.

[0003] Bio-based materials such as chitosan, polylactic acid, and zein have excellent film-forming properties and certain mechanical properties, and are also preferred raw materials for preparing packaging materials. However, there are problems such as poor barrier performance and limited mechanical properties after film formation of a single raw material. Therefore, Janus films, as a new concept of film materials, have emerged as the times require. The Janus films have asymmetric morphology or chemical composition, which makes them have some unique properties superior to other film materials and have great application potential in the field of food packaging materials.

[0004] At present, the preparation of Janus antibacterial films for food packaging is mostly carried out by the casting method. Although the preparation method is simple, the Janus films prepared by the method have problems such as weak bonding force between the two sides of the film, easy peeling or delamination. For example, patent application CN117924779A discloses a chitosan / zein slow-release antibacterial film with a Janus structure, a preparation method and application thereof. The preparation method is to use a polyphenol-plant essential oil Pickering emulsion as a delivery carrier of active substances, use chitosan and zein as raw materials, carry out multi-layer casting film formation in a film forming container, and prepare the film through a drying process. The method has the advantages of simple process and low cost, but has problems such as weak bonding between the two sides of the film and easy sliding.

[0005] Inspired by the surface characteristics of lotus leaves, the prior art discloses a three-layer Janus nanofiber film with a hydrophilic nanofiber layer (PAN) and a hydrophobic nanofiber middle layer (PVDF) prepared by a sequential electrospinning method. Although this preparation method can prepare nanofiber layers with different properties, the interface between the hydrophilic layer (PAN) and the hydrophobic layer (PVDF) in the three-layer Janus nanofiber film prepared by the method still has the problems of insufficient adhesion or uneven bonding, which leads to interlayer sliding or separation of the three-layer Janus nanofiber film during use, and the three-layer Janus nanofiber film is also easily contaminated in actual use, which leads to performance degradation and structural damage.

[0006] Furthermore, existing technologies have disclosed the preparation of three-layer Janus nanofiber membranes using a dual electrospinning method. However, although the dual electrospinning method can spin different solutions on different nozzles to prepare films with different properties on both sides, it often fails to effectively enhance the bonding force between the two sides of the film and between the film and the substrate, and is particularly prone to structural instability or insufficient durability during use.

[0007] In addition to the issue of the strong bonding between the two sides of the Janus film, its antibacterial and sustained-release properties also need to be considered when used in the food packaging field. However, existing technologies suffer from problems such as uncontrollable antibacterial agent release rates and significant impacts on the biological activity of antibacterial agents due to packaging material preparation methods.

[0008] Therefore, it is of great significance to study a method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure and its application in order to solve the above problems. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in the prior art and to provide a method for preparing a chitosan / polylactic acid / zein sustained-release antibacterial film based on the Janus structure and its application for food preservation.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing a Janus-based sustained-release antibacterial fiber membrane involves using a chitosan (CS) / polylactic acid (PLA) nanofiber membrane as the receiving substrate. The method employs a dual-needle parallel electrospinning or needleless electrospinning technique to spin a positively charged spinning solution A against a negatively charged spinning solution B to obtain an electrospun fiber membrane. The electrospun fiber membrane is then vacuum dried, heat-treated (at a temperature of 120–160 °C for 10–15 min), and shaped and cut to obtain the Janus-based sustained-release antibacterial fiber membrane.

[0012] Positively charged spinning solution A is obtained by adding a positively charged solution to a CUR@β-CD ICs / CS / PLA spinning solution, and negatively charged spinning solution B is obtained by adding a negatively charged solution to a zein spinning solution; or, positively charged spinning solution A is obtained by adding a positively charged solution to a zein spinning solution, and negatively charged spinning solution B is obtained by adding a negatively charged solution to a CUR@β-CD ICs / CS / PLA spinning solution;

[0013] The CUR@β-CD ICs / CS / PLA spinning solution is obtained by dissolving curcumin / β-cyclodextrin inclusion complex (CUR@β-CD ICs), chitosan, and polylactic acid in a solvent.

[0014] The zein used in this invention is a plant protein and a film-forming material that can be extracted from corn. Zein molecules themselves contain abundant polar groups and hydrophilic functional groups, which can interact with water molecules, thereby reducing water permeability. This property makes zein a natural moisture barrier agent. Therefore, the Zein membrane has good moisture and gas barrier properties. Furthermore, the Zein membrane can degrade under natural conditions, causing no pollution to the environment, making it a green and safe material.

[0015] This invention utilizes electrospinning technology to prepare a CUR@β-CD ICs / CS / PLA nanofiber membrane as an active loading layer. This nanofiber membrane has a large specific surface area and high porosity, and can respond to humidity stimulation in the packaging environment, thereby controlling the accurate release of curcumin at specific locations. It has broad application prospects in the field of active food packaging.

[0016] To address the issue of weak bonding between the two layers of Janus antibacterial membranes in existing technologies, this invention provides a first preparation method for a sustained-release antibacterial fiber membrane based on the Janus structure. This method involves cross-spinning CUR@β-CD ICs / CS / PLA spinning solution and Zein spinning solution, achieving fiber cross-entanglement and significantly enhancing the adhesion between the two fiber membranes. The unfolding of zein polypeptide chains exposes tyrosine residues, whose amino and carboxyl groups can form hydrogen bonds. Chitosan molecular chains contain amino and carboxyl groups, and zein and chitosan can be linked through electrostatic interactions, hydrogen bonds, and hydrophobic interactions, thereby enhancing the intermolecular forces between them. This invention fully utilizes the intermolecular interactions between zein and chitosan to further improve the bonding force between the fiber membranes. To further enhance the stability and durability of the fiber membrane, this invention also adds substances with different electrical properties to the two spinning solutions used for spinning. Through the principle of opposite charges attracting, this imparts a certain bonding force to the two films after spinning and enhances the adhesion of the zein membrane to the substrate. This results in a stronger bond between the two films and between the two films and the substrate, allowing the membrane to maintain its shape well under external forces during transportation and preventing slippage and damage. Furthermore, by performing heat treatment after electrospinning, thermal fusion bonding can occur between the different material molecules in the composite membrane, further increasing the bonding force of the composite membrane.

[0017] As a preferred technical solution:

[0018] The preparation method of the Janus-based sustained-release antibacterial fiber membrane described above, specifically the preparation process of the CUR@β-CD ICs / CS / PLA spinning solution, is as follows: Curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid are added to an acetic acid solution with a volume concentration of 60%, and heated and stirred at 50-60°C for 4-6 hours to obtain the CUR@β-CD ICs / CS / PLA spinning solution;

[0019] The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan, and polylactic acid relative to the acetic acid solution is 16-20% by mass / volume. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan, and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 2-5%, the mass percentage of chitosan is 85-90%, and the mass percentage of polylactic acid is 5-10%.

[0020] The specific preparation process of the curcumin / β-cyclodextrin inclusion complex is as follows: First, β-cyclodextrin is prepared into an aqueous solution, and curcumin is dissolved in ethanol to prepare a curcumin ethanol solution. Then, the curcumin ethanol solution is added to the β-cyclodextrin aqueous solution, and the mixture is stirred at 30-35℃ for 2.0-2.7 h. After that, the inclusion complex powder is obtained by freezing and centrifugation. Excess impurities are washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin is 0.95-1.02:1.

[0021] The preparation method of the Janus-based sustained-release antibacterial fiber membrane described above, the specific preparation process of the zein spinning solution is as follows: zein is added to a 70% acetic acid solution, the pH value is adjusted to 5-7, and the solution is heated and stirred at 50-60°C for 1 hour to obtain the zein spinning solution;

[0022] The mass / volume percentage of zein relative to the acetic acid solution is 1% to 5% (i.e., 1 to 5 g / 100 mL).

[0023] The preparation method of the Janus-based sustained-release antibacterial fiber membrane described above, the specific preparation process of the chitosan / polylactic acid nanofiber membrane is as follows: chitosan and polylactic acid are added to a mixed solution of dichloromethane and N,N-dimethylformamide to obtain a spinning solution, and the chitosan / polylactic acid nanofiber membrane is prepared by electrospinning.

[0024] The mass ratio of chitosan to polylactic acid is 70–90:10–30; the total mass / volume percentage of chitosan and polylactic acid relative to the mixed solution of dichloromethane and N,N-dimethylformamide is 5–7%; in the mixed solution of dichloromethane and N,N-dimethylformamide, the volume ratio of dichloromethane to N,N-dimethylformamide is 7:3.

[0025] The parameters for the dual-needle parallel electrospinning process are as follows: voltage 18-24kV, needle specification 22G, distance between positive and negative electrodes 15-20cm, spinning speed 1.6-1.8mL / h, roller speed 200rpm, spinning ambient temperature 22-25℃, and ambient humidity 25-40% RH.

[0026] The parameters for the needle-free electrospinning process are as follows: the coil spinneret is 20cm long and 8cm in diameter; the applied voltage is 55kV; the distance between the coil spinnerets is set to 10cm to reduce the effect of electrostatic repulsion; the collection distance is set to 25cm; and the production line speed is 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0027] The method for preparing a Janus-based sustained-release antibacterial fiber membrane, as described above, involves using a positively charged solution of 1 mM hexadecyltrimethylammonium bromide (CTAB) aqueous solution. CTAB powder is added to water preheated to 40–50°C and stirred until completely dissolved.

[0028] The negatively charged solution is an aqueous solution of negatively charged metal nanoparticles; the mass fraction of the negatively charged metal nanoparticle aqueous solution is 1%; the metal nanoparticles are gold nanoparticles, silver nanoparticles, zinc oxide nanoparticles, ferrite (such as Fe3O4) nanoparticles, or titanium dioxide (TiO2) nanoparticles; the metal nanoparticles are formed by dissolving metal salts or metal precursors in water, ethanol, or acetone, and then adding them to a reducing agent or precipitant; for silver and gold nanoparticles, commonly used reducing agents are hydrogen, sodium borohydride (NaBH4), or citric acid; for zinc oxide nanoparticles, commonly used precipitants are dilute acids (such as nitric acid), sodium hydroxide solution (for alkaline conditions), or other organic solvents; for ferrite and titanium dioxide nanoparticles, they are usually synthesized by appropriate precipitation or hydrothermal methods; finally, appropriate ultrasonic treatment or stirring is used to ensure that the nanoparticles are uniformly dispersed in the aqueous solution and maintain stability.

[0029] For gold, silver, and titanium dioxide nanoparticles, the surface of the metal nanoparticles adsorbs negative ions or organic matter (such as chloride ions or organic molecules), thus making them negatively charged; zinc oxide nanoparticles, in aqueous solution, form zinc oxide on the surface that reacts with ions in the water, resulting in negatively charged ZnO nanoparticles; ferrite nanoparticles (such as Fe3O4) become negatively charged in water due to hydroxides or other reactive substances on their surface.

[0030] The volume percentage of the positively or negatively charged solution added relative to the CUR@β-CD ICs / CS / PLA spinning solution or zein spinning solution is 1% to 2%.

[0031] The parameters for the dual-needle parallel electrospinning process of CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 16-22kV, needle specification 20G, distance between positive and negative electrodes 15-20cm, spinning speed 0.5-1.0mL / h, roller speed 200rpm, spinning ambient temperature 22-25℃, and ambient humidity 25-40% RH.

[0032] The needle-free electrospinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membranes are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets set to 10cm to reduce the effect of electrostatic repulsion, collection distance set to 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0033] The parameters for the dual-needle parallel electrospinning process of zein membrane are as follows: voltage 16-22kV, needle specification 20G, distance between positive and negative electrodes 15-20cm, spinning speed 0.5-1.0mL / h, roller speed 200rpm, spinning ambient temperature 22-25℃, and ambient humidity 25-40%RH.

[0034] The needle-free electrospinning process parameters for zein membrane are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets set to 10cm to reduce the effect of electrostatic repulsion, collection distance set to 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0035] This invention also provides a method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure. Using a petal-shaped nano-ZnO fiber membrane as the receiving substrate, a positively charged spinning solution C and a positively charged spinning solution D are spun together to obtain an electrospun fiber membrane by using a dual-needle parallel electrospinning or needleless electrospinning method. The electrospun fiber membrane is then vacuum dried, heat-treated (at a temperature of 120–160°C for 10–15 min), and shaped and cut to obtain a sustained-release antibacterial fiber membrane based on the Janus structure.

[0036] The petal-shaped nano-ZnO fiber membrane is prepared by electrochemical deposition (ECD) using zinc foil as a substrate to form a superhydrophobic surface and achieve more effective water-repellent effect.

[0037] The electrolyte used in electrochemical deposition is a mixture of (NH4)2SO4 solution, ZnSO4 solution and NaOH solution, with a pH value of 7.5 to 9.5;

[0038] The electrochemical deposition process ensures that the petal-shaped ZnO nanofiber membrane is negatively charged by controlling the following factors during electrodeposition: ① Higher pH value: ZnO exhibits a negative charge in an alkaline environment, therefore deposition can be carried out at a higher pH value to promote the negative charge of the ZnO membrane. ② Electrolyte composition: Electrolytes containing a high concentration of negative ions (such as sulfates or chlorides; this invention selected (NH4)2SO4) can promote the formation of negative charges on the ZnO surface. These ions may adsorb onto the ZnO surface, increasing its negative charge density;

[0039] The specific preparation steps for the petal-shaped ZnO nanofiber membrane are as follows:

[0040] (1) Use 1M hydrochloric acid to treat a sample with dimensions of 1cm × 1c m The zinc foil is cleaned to remove the passive oxide layer on the zinc foil, and then thoroughly rinsed with deionized water (DI);

[0041] (2) Stir a 2M aqueous solution of (NH4)2SO4 and a 0.1M aqueous solution of ZnSO4 in a magnetic stirrer for 20 minutes to ensure uniform mixing. Then add a 1M aqueous solution of NaOH and continue stirring for 10 minutes to adjust the pH to 7.5-9.5 to ensure that the electrodeposition process is in a slightly alkaline state, which is the electrolyte. The mass ratio of (NH4)2SO4, ZnSO4 and NaOH is 16.4:1:2.5.

[0042] (3) The electrolyte was placed in an unisolated beaker, which was then placed in an electrodeposition tank. Zinc foil was then used as the working electrode and a platinum rod as the counter electrode, and electrodeposition was performed in the unisolated beaker with a 1 cm gap between the two electrodes. Finally, the deposited film was removed from the tank, thoroughly washed with deionized water, and dried in a vacuum oven for 24 hours to obtain a petal-shaped nano-ZnO fiber membrane. The electrodeposition current density was 0.5 A / cm². -2 The deposition process is divided into three stages, with deposition times of 200s, 300s, and 400s respectively, and an interval of 5 minutes between each stage.

[0043] Positively charged spinning solution C is obtained by adding a positively charged solution to the CUR@β-CD ICs / CS / PLA spinning solution, and positively charged spinning solution D is obtained by adding a positively charged solution to the zein spinning solution.

[0044] The CUR@β-CD ICs / CS / PLA spinning solution is obtained by dissolving curcumin / β-cyclodextrin inclusion complex (CUR@β-CD ICs), chitosan, and polylactic acid in a solvent.

[0045] To address the issue of weak bonding between the two sides of the Janus antibacterial membrane in existing technologies, this invention provides a second preparation method for a sustained-release antibacterial fiber membrane based on the Janus structure. Using a petal-shaped nano-ZnO fiber membrane as the receiving substrate, a dual-needle parallel electrospinning method is employed to spin CUR@β-CDICs / CS / PLA spinning solution and Zein spinning solution together. Positively charged substances are added to both spinning solutions to bond with the negatively charged receiving substrate. Through the principle of opposite charges attracting, the adhesion of the zein membrane and CUR@β-CDICs / CS / PLA membrane to the substrate is enhanced, resulting in a stronger bond between the two films and the substrate. Furthermore, this invention innovatively uses electrodeposition to generate petal-shaped nanostructures on the zinc foil surface, increasing surface roughness and hydrophobicity. This, combined with the moisture-blocking effect of the outermost zein membrane, achieves better water-repellent properties. Moreover, due to the Zn... 2+ Zn readily diffuses into the bacterial biofilm (i.e., the biofilm formed by bacteria), and diffuses into the bacterial biofilm. 2+ This process can interfere with bacterial enzyme activity, inhibit protein synthesis, and disrupt bacterial cell membrane structure, thereby resulting in a sustained-release antibacterial fiber membrane with superior antibacterial effects. Therefore, the sustained-release antibacterial fiber membrane based on the Janus structure prepared in this invention can be well applied in the field of food packaging materials.

[0046] As a preferred technical solution:

[0047] The preparation method of the Janus-based sustained-release antibacterial fiber membrane described above, specifically the preparation process of the CUR@β-CD ICs / CS / PLA spinning solution, is as follows: Curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid are added to an acetic acid solution with a volume concentration of 60%, and heated and stirred at 50-60°C for 4-6 hours to obtain the CUR@β-CD ICs / CS / PLA spinning solution;

[0048] The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan, and polylactic acid relative to the acetic acid solution is 16-20% by mass / volume. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan, and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 2-5%, the mass percentage of chitosan is 85-90%, and the mass percentage of polylactic acid is 5-10%.

[0049] The specific preparation process of the curcumin / β-cyclodextrin inclusion complex is as follows: First, β-cyclodextrin is prepared into an aqueous solution, and curcumin is dissolved in ethanol to prepare a curcumin ethanol solution. Then, the curcumin ethanol solution is added to the β-cyclodextrin aqueous solution, and the mixture is stirred at 30-35℃ for 2.0-2.7 h. After that, the inclusion complex powder is obtained by freezing and centrifugation. Excess impurities are washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin is 0.95-1.02:1.

[0050] The preparation method of the Janus-based sustained-release antibacterial fiber membrane described above, the specific preparation process of the zein spinning solution is as follows: zein is added to a 70% acetic acid solution, the pH value is adjusted to 5-7, and the solution is heated and stirred at 50-60°C for 1 hour to obtain the zein spinning solution;

[0051] The mass / volume percentage of zein relative to the acetic acid solution is 1% to 5%.

[0052] As described above, the method for preparing a Janus-based sustained-release antibacterial fiber membrane involves a positively charged solution obtained by dissolving PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-doped polystyrene sulfonate) powder in water to a concentration of 1 mM.

[0053] The positively charged solution accounts for 1% to 2% of the volume of the CUR@β-CD ICs / CS / PLA spinning solution or the zein spinning solution.

[0054] The parameters for the dual-needle parallel electrospinning process of CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 16-22kV, needle specification 20G, distance between positive and negative electrodes 15-20cm, spinning speed 0.5-1.0mL / h, roller speed 200rpm, spinning ambient temperature 22-25℃, and ambient humidity 25-40% RH.

[0055] The needle-free electrospinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membranes are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets set to 10cm to reduce the effect of electrostatic repulsion, collection distance set to 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0056] The parameters for the dual-needle parallel electrospinning process of zein membrane are as follows: voltage 16-22kV, needle specification 20G, distance between positive and negative electrodes 15-20cm, spinning speed 0.5-1.0mL / h, roller speed 200rpm, spinning ambient temperature 22-25℃, and ambient humidity 25-40%RH.

[0057] The needle-free electrospinning process parameters for zein membrane are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets set to 10cm to reduce the effect of electrostatic repulsion, collection distance set to 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0058] The present invention also provides the application of the Janus-based slow-release antibacterial fiber membrane prepared by the preparation method described in any of the preceding claims for food preservation.

[0059] Beneficial effects:

[0060] (1) This invention innovatively utilizes the principle of attraction between opposite charges to significantly enhance the bonding force between the two films and the substrate through a specific treatment method, thereby effectively solving the problem of weak bonding between the two films in the prior art, and has significant application potential and technical advantages.

[0061] (2) The electrospinning technology used in this invention has mild operating conditions, does not damage the bioactivity of curcumin, and is low in cost and simple in process.

[0062] (3) The present invention utilizes CUR@β-CD ICs / CS / PLA nanofiber membrane prepared by electrospinning technology as an active loading layer. This nanofiber membrane has a large specific surface area and high porosity, and can respond to the humidity stimulation in the packaging environment, thereby controlling the accurate release of curcumin at a specific location. It has broad application prospects in the field of active food packaging.

[0063] (4) Because curcumin is a natural antibacterial agent with broad-spectrum antibacterial properties, the nanofiber membrane loaded with curcumin inclusion complex prepared in this invention has good antibacterial properties and is gradually released through a sustained-release mechanism to ensure long-term antibacterial effect. In addition, the natural antibacterial agent used in this invention is added to the active packaging material of food and will not have any impact on human health. Detailed Implementation

[0064] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0065] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0066] Elongation at break and tensile strength: The Janus-based slow-release antibacterial fiber membranes prepared in each embodiment and comparative example were first cut into samples of 10mm × 100mm. Then, the elongation at break and tensile strength of the samples were tested using a universal tensile testing machine (Jinan Hengxu Co., Ltd.). The tensile rate was 200mm / min.

[0067] Water vapor transmission rate and oxygen transmission rate: Referring to GB / T 1037-2021 "Determination of Water Vapor Transmission Performance of Plastic Films and Sheets - Cup Weight Gain and Loss Method", the Janus-based slow-release antibacterial fiber membranes prepared in each example and comparative example were tested. The Janus-based slow-release antibacterial fiber membrane was fixed at the opening of a 50mL centrifuge tube with an opening diameter of 26.5mm. 20.0±0.5g of anhydrous silica gel and 20.0±0.5g of deoxygenation bag were placed in the centrifuge tube, respectively. The mass change of the centrifuge tube was continuously recorded until day 7 under conditions of 75% RH humidity and 25℃. Accurate weighing was then performed, and the water vapor transmission rate and oxygen transmission rate were calculated according to the formula.

[0068] The formula for calculating water vapor transmission rate is as follows:

[0069]

[0070] In the formula, Δm represents the mass difference before and after the centrifuge tube, e represents the thickness of the membrane, t represents the measurement time, A represents the area of ​​the centrifuge tube opening, and Δp represents the vapor pressure at 25℃.

[0071] The formula for calculating oxygen permeability is as follows:

[0072]

[0073] In the formula, Δm represents the mass difference before and after the centrifuge tube, t represents the measurement time, and A represents the area of ​​the centrifuge tube opening.

[0074] Colony count of *E. coli*: Using the standard microbial detection method (AOAC method), with Gram-negative *Escherichia coli* (ATCC25922) as a representative bacterial model, the OD value of the bacterial culture at 600 nm was first measured using a microplate reader (Spectra MAX19, Meigu Molecular Instruments Co., Ltd.). Then, the *E. coli* stock solution was diluted 1×10⁻⁶ using the corresponding culture medium. 5 Subsequently, the Janus-based slow-release antibacterial fiber membranes prepared in each example and comparative example were inoculated into the culture medium, and 100 μL of diluted Escherichia coli stock solution was added to them. The membranes were then incubated in a 37°C incubator for 4 h, with a membrane-free sample as a blank control. Finally, 50 μL of the Escherichia coli mixture was taken from the culture medium after the incubation and spread onto solid agar medium. The culture was then incubated in a 37°C incubator for 24 h to observe the colony growth and count the colonies.

[0075] Colony count of Staphylococcus aureus: Using the standard microbial detection method (AOAC method), with Gram-positive Staphylococcus aureus (ATCC25923) as a representative bacterial model, the OD value of Staphylococcus aureus at 600 nm was first measured using a microplate reader (Spectra MAX19, Meigu Molecular Instruments Co., Ltd.). Then, the Staphylococcus aureus was diluted 1×10⁻⁶ using the corresponding culture medium. 5 The Janus-based slow-release antibacterial fiber membranes prepared in each example and comparative example were then inoculated into the culture medium, and 100 μL of diluted Staphylococcus aureus was added. The membranes were then incubated in a 37°C incubator for 4 h, with a membrane-free sample as a blank control. Finally, 50 μL of the Staphylococcus aureus mixture was taken from the culture medium after the incubation and spread onto a solid agar medium. The culture was then incubated in a 37°C incubator for 24 h to observe the colony growth and count the colonies.

[0076] Antibacterial rate: The Janus-based sustained-release antibacterial fiber membranes prepared in each example and comparative example were tested according to the standard antibacterial test method AATCC 100. The antibacterial performance of the nanofiber membranes was evaluated by plate count method.

[0077] Curcumin release amount: First, the base membrane and side membrane of the Janus-structure-based sustained-release antibacterial fiber membranes prepared in each example and comparative example were separated. Then, the concentration of curcumin in each layer was measured according to GB 31604.8-2021 "National Food Safety Standard for Determination of Total Migration of Food Contact Materials and Articles" (PBS buffer solution (pH=7.0) was selected as the ordinary food simulation solution, and the measurement was carried out at 4℃). Then, the release amount was calculated according to the measured concentration and sampling volume using the following formula:

[0078] Released Amount = (C t ×V×D)-(C0×V×D);

[0079] In the formula, C t C0 is the curcumin concentration at time t (mg / L), V is the initial concentration (mg / L), D is the sampling volume (L), and D is the dilution factor.

[0080] Weight loss rate: The Janus-based sustained-release antibacterial fiber membranes prepared in each example and comparative example were used as samples and tested for 4 days at a temperature of 25°C and a relative humidity of 60%. The initial mass and the mass after 96 hours of treatment were recorded by weighing method. The weight loss rate was calculated by the formula: (initial mass - mass after treatment) / initial mass × 100%.

[0081] Example 1

[0082] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0083] (1) Preparation of raw materials;

[0084] β-Cyclodextrin;

[0085] water;

[0086] Curcumin;

[0087] Ethanol;

[0088] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0089] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0090] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0091] Hexadecyltrimethylammonium bromide;

[0092] Metal salt: Chloroauric acid (HAuCl4);

[0093] Reducing agent: Prepare a 0.1M sodium borohydride solution by mixing sodium borohydride and water;

[0094] Dichloromethane;

[0095] N,N-dimethylformamide;

[0096] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0097] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 30 °C for 2.7 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 0.95:1.

[0098] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) are added to an aqueous acetic acid solution with a volume concentration of 60%. After heating and stirring at 50°C for 6 hours, the CUR@β-CD ICs / CS / PLA spinning solution is obtained. The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid is 16% by mass / volume relative to the aqueous acetic acid solution. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 5%, the mass percentage of chitosan is 85% and the mass percentage of polylactic acid is 10%.

[0099] (3) Preparation of corn glycidol spinning solution;

[0100] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 7, and the solution was heated and stirred at 60°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 5%;

[0101] (4) Prepare aqueous solutions of hexadecyltrimethylammonium bromide and negatively charged metal nanoparticles;

[0102] (4.1) Prepare an aqueous solution of hexadecyltrimethylammonium bromide;

[0103] Add hexadecyltrimethylammonium bromide powder to water preheated to 50°C and stir until completely dissolved to obtain a 1 mM aqueous solution of hexadecyltrimethylammonium bromide.

[0104] (4.2) Preparation of aqueous solution of negatively charged metal nanoparticles;

[0105] After dissolving the metal salt in water at a mass ratio of 1:15, a reducing agent was added and stirred to ensure uniform dispersion. Citric acid was then added, and the mixture was reacted at 70°C and 760 mmHg for 2 hours to form gold nanoparticles. The mixture was then cooled to 25°C and added to water. Ultrasonic treatment was then used to ensure uniform dispersion of the gold nanoparticles in the water, resulting in a 1% (w / w) aqueous solution of negatively charged metal nanoparticles. The amount of citric acid added was 6% of the amount of metal salt added, and the mass ratio of metal salt to reducing agent was 1:7.

[0106] (5) Prepare positively charged spinning solution A and negatively charged spinning solution B;

[0107] A hexadecyltrimethylammonium bromide aqueous solution was added to a zein spinning solution to obtain a positively charged spinning solution A; wherein the volume percentage of the hexadecyltrimethylammonium bromide aqueous solution relative to the zein spinning solution was 2%;

[0108] A negatively charged aqueous solution of metal nanoparticles was added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a negatively charged spinning solution B; wherein the volume percentage of the negatively charged aqueous solution of metal nanoparticles relative to the CUR@β-CD ICs / CS / PLA spinning solution was 1%.

[0109] (6) Preparation of chitosan / polylactic acid nanofiber membrane;

[0110] Chitosan and polylactic acid were added to a mixed solution of dichloromethane and N,N-dimethylformamide to obtain a spinning solution. Chitosan / polylactic acid nanofiber membranes were prepared using a dual-needle parallel electrospinning method. The mass ratio of chitosan to polylactic acid was 70:30; the total mass / volume percentage of chitosan and polylactic acid relative to the mixed solution of dichloromethane and N,N-dimethylformamide was 7%; and the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solution was 7:3.

[0111] The electrospinning process parameters are as follows: voltage is 18kV, needle specification is 22G, distance between positive and negative electrodes is 15cm, spinning speed is 1.8mL / h, roller speed is 200rpm, spinning ambient temperature is 22℃, and ambient humidity is 40% RH.

[0112] (7) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0113] Using the chitosan / polylactic acid nanofiber membrane obtained in step (6) as the receiving substrate, a double-needle parallel electrospinning method was used to spin the positively charged spinning solution A and the negatively charged spinning solution B obtained in step (4) to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane on both sides of the receiving substrate. Then, after vacuum drying, heat treatment and shaping and cutting, a slow-release antibacterial fiber membrane based on the Janus structure was obtained. The heat treatment temperature was 160℃ and the time was 10min.

[0114] The spinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 22kV, needle size 20G, distance between positive and negative electrodes 20cm, spinning speed 0.8mL / h, roller speed 200rpm, spinning ambient temperature 22℃, and ambient humidity 34%RH.

[0115] The spinning process parameters for the corn glycerin membrane are as follows: voltage 22kV, needle size 20G, distance between positive and negative electrodes 20cm, spinning speed 1mL / h, roller speed 200rpm, spinning ambient temperature 25℃, and ambient humidity 40%RH.

[0116] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 58 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, 155 μm for the zein membrane, and 234 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 40.7%, a tensile strength of 7.3 MPa, and a water vapor permeability of 7.5 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 6.9×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 11 CFU, and the bacterial count of *Staphylococcus aureus* was 17 CFU. The inhibition rate of *E. coli* was 98.43%, and the inhibition rate of *Staphylococcus aureus* was 97.85%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.17 nL / cm. 2 The release rate of curcumin in the zein membrane was 0.1 nL / cm. 2 .

[0117] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0118] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0119] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 14.43%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0120] Example 2

[0121] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0122] (1) Preparation of raw materials;

[0123] β-Cyclodextrin;

[0124] water;

[0125] Curcumin;

[0126] Ethanol;

[0127] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0128] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0129] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0130] Hexadecyltrimethylammonium bromide;

[0131] Metal salt: Silver nitrate (AgNO3);

[0132] Reducing agent: citric acid;

[0133] Dichloromethane;

[0134] N,N-dimethylformamide;

[0135] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0136] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 32 °C for 2.4 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 0.98:1.

[0137] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) are added to an aqueous acetic acid solution with a volume concentration of 60%. After heating and stirring at 55°C for 5 hours, the CUR@β-CD ICs / CS / PLA spinning solution is obtained. The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid is 18% by mass / volume relative to the aqueous acetic acid solution. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 2%, the mass percentage of chitosan is 90% and the mass percentage of polylactic acid is 8%.

[0138] (3) Preparation of corn glycidol spinning solution;

[0139] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 6, and the mixture was heated and stirred at 55°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 3%;

[0140] (4) Prepare aqueous solutions of hexadecyltrimethylammonium bromide and negatively charged metal nanoparticles;

[0141] (4.1) Prepare an aqueous solution of hexadecyltrimethylammonium bromide;

[0142] Add hexadecyltrimethylammonium bromide powder to water preheated to 45°C and stir until completely dissolved to obtain a 1 mM aqueous solution of hexadecyltrimethylammonium bromide.

[0143] (4.2) Preparation of aqueous solution of negatively charged metal nanoparticles;

[0144] The metal salt was dissolved in water at a mass ratio of 1:15, and then added to a reducing agent. After reacting at 70℃ and 760 mmHg pressure for 2 hours, silver nanoparticles were formed. The solution was then cooled to 25℃ and added back into water. Finally, the silver nanoparticles were stirred to uniformly disperse in the water, resulting in a 1% (w / w) aqueous solution of negatively charged titanium dioxide nanoparticles. The mass ratio of the metal salt to the reducing agent was 1:5.

[0145] (5) Prepare positively charged spinning solution A and negatively charged spinning solution B;

[0146] A hexadecyltrimethylammonium bromide aqueous solution was added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a positively charged spinning solution A; wherein the volume percentage of the hexadecyltrimethylammonium bromide aqueous solution relative to the CUR@β-CD ICs / CS / PLA spinning solution was 1%;

[0147] A negatively charged aqueous solution of metal nanoparticles was added to a zein spinning solution to obtain a negatively charged spinning solution B; wherein the volume percentage of the negatively charged aqueous solution of metal nanoparticles relative to the zein spinning solution was 2%.

[0148] (6) Preparation of chitosan / polylactic acid nanofiber membrane;

[0149] Chitosan and polylactic acid were added to a mixed solution of dichloromethane and N,N-dimethylformamide to obtain a spinning solution. Chitosan / polylactic acid nanofiber membranes were prepared using a needle-free electrospinning method. The mass ratio of chitosan to polylactic acid was 75:25; the total mass / volume percentage of chitosan and polylactic acid relative to the mixed solution of dichloromethane and N,N-dimethylformamide was 6%; and the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solution was 7:3.

[0150] The needle-free electrospinning process parameters for chitosan / polylactic acid nanofiber membranes are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets 10cm, collection distance 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0151] (7) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0152] Using the chitosan / polylactic acid nanofiber membrane obtained in step (6) as the receiving substrate, a needle-free electrospinning method was used to spin the positively charged spinning solution A and the negatively charged spinning solution B obtained in step (4) to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane on both sides of the receiving substrate. Then, after vacuum drying, heat treatment and shaping and cutting, a slow-release antibacterial fiber membrane based on the Janus structure was obtained. The heat treatment temperature was 140℃ and the time was 13min.

[0153] The needle-free electrospinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membranes are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets 10cm, collection distance 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0154] The needle-free electrospinning process parameters for corn glycerin membrane are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets 10cm, collection distance 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0155] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 61 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, a thickness of 164 μm for the zein membrane, and a thickness of 255 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 46.2%, a tensile strength of 7.6 MPa, and a water vapor permeability of 7.3 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 7.1×10 -5 g / m 2 The colony count of *Escherichia coli* was 101 g CFU / g, and the colony count of *Staphylococcus aureus* was 10 CFU. The inhibition rate of *E. coli* was 98.57%, and the inhibition rate of *Staphylococcus aureus* was 98.73%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.13 L / cm³. 2 The release rate of curcumin in the zein membrane was 0.09 L / cm. 2 .

[0156] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0157] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0158] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 13.07%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0159] Example 3

[0160] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0161] (1) Preparation of raw materials;

[0162] β-Cyclodextrin;

[0163] water;

[0164] Curcumin;

[0165] Ethanol;

[0166] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0167] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0168] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0169] Hexadecyltrimethylammonium bromide;

[0170] Metal salt: Zinc chloride;

[0171] Precipitating agent: 1M ammonia solution;

[0172] Dichloromethane;

[0173] N,N-dimethylformamide;

[0174] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0175] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 35 °C for 2 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 1.02:1.

[0176] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) are added to an aqueous acetic acid solution with a volume concentration of 60%. After heating and stirring at 60°C for 4 hours, the CUR@β-CD ICs / CS / PLA spinning solution is obtained. The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid is 20% by mass / volume relative to the aqueous acetic acid solution. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 5%, the mass percentage of chitosan is 90% and the mass percentage of polylactic acid is 5%.

[0177] (3) Preparation of corn glycidol spinning solution;

[0178] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 5, and the solution was heated and stirred at 50°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 1%;

[0179] (4) Prepare aqueous solutions of hexadecyltrimethylammonium bromide and negatively charged metal nanoparticles;

[0180] (4.1) Prepare an aqueous solution of hexadecyltrimethylammonium bromide;

[0181] Add hexadecyltrimethylammonium bromide powder to water preheated to 40°C and stir until completely dissolved to obtain a 1 mM aqueous solution of hexadecyltrimethylammonium bromide.

[0182] (4.2) Preparation of aqueous solution of negatively charged metal nanoparticles;

[0183] The metal salt was dissolved in water at a mass ratio of 1:15, and then added to a precipitant. After reacting at 70℃ and 760 mmHg pressure for 2 hours, zinc oxide nanoparticles were formed. The solution was then cooled to 25℃ and added back into water. Finally, the zinc oxide nanoparticles were uniformly dispersed in the water by ultrasonic treatment or stirring to obtain a 1% (w / w) aqueous solution of negatively charged titanium dioxide nanoparticles. The mass ratio of the metal salt to the precipitant was 1:3.

[0184] (5) Prepare positively charged spinning solution A and negatively charged spinning solution B;

[0185] A hexadecyltrimethylammonium bromide aqueous solution was added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a positively charged spinning solution A; wherein the volume percentage of the hexadecyltrimethylammonium bromide aqueous solution relative to the CUR@β-CD ICs / CS / PLA spinning solution was 2%;

[0186] A negatively charged aqueous solution of metal nanoparticles was added to a zein spinning solution to obtain a negatively charged spinning solution B; wherein the volume percentage of the negatively charged aqueous solution of metal nanoparticles relative to the zein spinning solution was 1%.

[0187] (6) Preparation of chitosan / polylactic acid nanofiber membrane;

[0188] Chitosan and polylactic acid were added to a mixed solution of dichloromethane and N,N-dimethylformamide to obtain a spinning solution. Chitosan / polylactic acid nanofiber membranes were prepared using a dual-needle parallel electrospinning method. The mass ratio of chitosan to polylactic acid was 70:30; the total mass / volume percentage of chitosan and polylactic acid relative to the mixed solution of dichloromethane and N,N-dimethylformamide was 5%; and the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solution was 7:3.

[0189] The electrospinning process parameters are as follows: voltage is 24kV, needle size is 22G, distance between positive and negative electrodes is 20cm, spinning speed is 1.6mL / h, roller speed is 200rpm, spinning ambient temperature is 23℃, and ambient humidity is 25% RH.

[0190] (7) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0191] Using the chitosan / polylactic acid nanofiber membrane obtained in step (6) as the receiving substrate, a double-needle parallel electrospinning method was used to spin the positively charged spinning solution A and the negatively charged spinning solution B obtained in step (4) to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane on both sides of the receiving substrate. Then, after vacuum drying, heat treatment and shaping and cutting, a slow-release antibacterial fiber membrane based on the Janus structure was obtained. The heat treatment temperature was 120℃ and the time was 15min.

[0192] The spinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 16kV, needle specification 20G, distance between positive and negative electrodes 15cm, spinning speed 0.5mL / h, roller speed 200rpm, spinning ambient temperature 25℃, and ambient humidity 40% RH.

[0193] The spinning process parameters for the corn glycerin membrane are as follows: voltage 16kV, needle specification 20G, distance between positive and negative electrodes 15cm, spinning speed 0.5mL / h, roller speed 200rpm, spinning ambient temperature 22℃, and ambient humidity 25% RH.

[0194] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 73 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, 179 μm for the zein membrane, and 278 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 56.3%, a tensile strength of 8.5 MPa, and a water vapor permeability of 8.5 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 7.4×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 12 CFU, and the bacterial count of *Staphylococcus aureus* was 11 CFU. The inhibition rate of *E. coli* was 98.29%, and the inhibition rate of *Staphylococcus aureus* was 98.61%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.12 L / cm³. 2 The release rate of curcumin in the zein membrane was 0.07 L / cm. 2 .

[0195] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0196] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0197] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 12.77%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0198] Example 4

[0199] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0200] (1) Preparation of raw materials;

[0201] β-Cyclodextrin;

[0202] water;

[0203] Curcumin;

[0204] Ethanol;

[0205] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0206] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0207] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0208] Hexadecyltrimethylammonium bromide;

[0209] Metal salt: Ferric chloride;

[0210] Precipitating agent: 1M ammonia solution;

[0211] Dichloromethane;

[0212] N,N-dimethylformamide;

[0213] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0214] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 33 °C for 2 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 0.972:1.

[0215] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) were added to an aqueous acetic acid solution with a volume concentration of 60%. After heating and stirring at 55°C for 5 hours, the CUR@β-CD ICs / CS / PLA spinning solution was obtained. The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid was 17% by mass / volume relative to the aqueous acetic acid solution. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex was 4%, the mass percentage of chitosan was 89% and the mass percentage of polylactic acid was 7%.

[0216] (3) Preparation of corn glycidol spinning solution;

[0217] Zeatin was added to a 70% (v / v) aqueous solution of acetic acid, the pH was adjusted to 7, and the solution was heated and stirred at 55°C for 1 hour to obtain a zeatin spinning solution; wherein the mass / volume percentage of zeatin relative to the acetic acid solution was 2%;

[0218] (4) Prepare aqueous solutions of hexadecyltrimethylammonium bromide and negatively charged metal nanoparticles;

[0219] (4.1) Prepare an aqueous solution of hexadecyltrimethylammonium bromide;

[0220] Add hexadecyltrimethylammonium bromide powder to water preheated to 50°C and stir until completely dissolved to obtain a 1 mM aqueous solution of hexadecyltrimethylammonium bromide.

[0221] (4.2) Preparation of aqueous solution of negatively charged metal nanoparticles;

[0222] Metal salts were dissolved in water at a mass ratio of 1:15, then added to a precipitant and reacted at 70°C and 760 mmHg for 2 hours to form ferrite nanoparticles. The precipitant was then cooled to 25°C and added to water. Finally, ultrasonic treatment was used to uniformly disperse the ferrite nanoparticles in the water, resulting in a 1% (w / w) aqueous solution of negatively charged titanium dioxide nanoparticles. The mass ratio of metal salt to precipitant was 1:2.

[0223] (5) Prepare positively charged spinning solution A and negatively charged spinning solution B;

[0224] A hexadecyltrimethylammonium bromide aqueous solution was added to a zein spinning solution to obtain a positively charged spinning solution A; wherein the volume percentage of the hexadecyltrimethylammonium bromide aqueous solution relative to the zein spinning solution was 1.7%;

[0225] A negatively charged aqueous solution of metal nanoparticles was added to a CUR@β-CD ICs / CS / PLA spinning solution to obtain a negatively charged spinning solution B; wherein the volume percentage of the negatively charged aqueous solution of metal nanoparticles relative to the CUR@β-CD ICs / CS / PLA spinning solution was 1.7%.

[0226] (6) Preparation of chitosan / polylactic acid nanofiber membrane;

[0227] Chitosan and polylactic acid were added to a mixed solution of dichloromethane and N,N-dimethylformamide to obtain a spinning solution. Chitosan / polylactic acid nanofiber membranes were prepared using a dual-needle parallel electrospinning method. The mass ratio of chitosan to polylactic acid was 80:20; the total mass / volume percentage of chitosan and polylactic acid relative to the mixed solution of dichloromethane and N,N-dimethylformamide was 5%; and the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solution was 7:3.

[0228] The electrospinning process parameters are as follows: voltage is 23kV, needle size is 22G, distance between positive and negative electrodes is 18cm, spinning speed is 1.8mL / h, roller speed is 200rpm, spinning ambient temperature is 24℃, and ambient humidity is 35% RH.

[0229] (7) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0230] Using the chitosan / polylactic acid nanofiber membrane obtained in step (6) as the receiving substrate, a double-needle parallel electrospinning method was used to spin the positively charged spinning solution A and the negatively charged spinning solution B obtained in step (4) to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane on both sides of the receiving substrate. Then, after vacuum drying, heat treatment and shaping and cutting, a slow-release antibacterial fiber membrane based on the Janus structure was obtained. The heat treatment temperature was 145℃ and the time was 15min.

[0231] The spinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 20kV, needle specification 20G, distance between positive and negative electrodes 16cm, spinning speed 0.8mL / h, roller speed 200rpm, spinning ambient temperature 23℃, and ambient humidity 35% RH.

[0232] The spinning process parameters for the corn glycerin membrane are as follows: voltage 18kV, needle specification 20G, distance between positive and negative electrodes 20cm, spinning speed 0.9mL / h, roller speed 200rpm, spinning ambient temperature 24℃, and ambient humidity 35% RH.

[0233] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 64 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, 171 μm for the zein membrane, and 265 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 58.6%, a tensile strength of 10.1 MPa, and a water vapor permeability of 7.4 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 8.1×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 11 CFU, and the bacterial count of *Staphylococcus aureus* was 15 CFU. The inhibition rate of *E. coli* was 98.43%, and the inhibition rate of *Staphylococcus aureus* was 98.1%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.15 L / cm³. 2 The release rate of curcumin from the zein membrane was 0.08 L / cm. 2 .

[0234] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0235] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0236] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 15.42%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0237] Example 5

[0238] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0239] (1) Preparation of raw materials;

[0240] β-Cyclodextrin;

[0241] water;

[0242] Curcumin;

[0243] Ethanol;

[0244] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0245] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0246] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0247] Hexadecyltrimethylammonium bromide;

[0248] Metal salt: Tetrabutyl titanate;

[0249] water;

[0250] Dichloromethane;

[0251] N,N-dimethylformamide;

[0252] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0253] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 34 °C for 2 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 0.99:1.

[0254] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) are added to an aqueous acetic acid solution with a volume concentration of 60%. After heating and stirring at 60°C for 5 hours, the CUR@β-CD ICs / CS / PLA spinning solution is obtained. The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid is 18% by mass / volume relative to the aqueous acetic acid solution. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 3%, the mass percentage of chitosan is 88% and the mass percentage of polylactic acid is 9%.

[0255] (3) Preparation of corn glycidol spinning solution;

[0256] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 7, and the solution was heated and stirred at 60°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 4%;

[0257] (4) Prepare aqueous solutions of hexadecyltrimethylammonium bromide and negatively charged metal nanoparticles;

[0258] (4.1) Prepare an aqueous solution of hexadecyltrimethylammonium bromide;

[0259] Add hexadecyltrimethylammonium bromide powder to water preheated to 50°C and stir until completely dissolved to obtain a 1 mM aqueous solution of hexadecyltrimethylammonium bromide.

[0260] (4.2) Preparation of aqueous solution of negatively charged metal nanoparticles;

[0261] Metal salts were dissolved in water at a mass ratio of 1:15, and then reacted at 70℃ and 760mmHg pressure for 2 hours to form titanium dioxide nanoparticles. After cooling to 25℃, they were added to water. Finally, ultrasonic treatment was used to uniformly disperse the titanium dioxide nanoparticles in water to obtain a 1% (by mass) aqueous solution of negatively charged titanium dioxide nanoparticles.

[0262] (5) Prepare positively charged spinning solution A and negatively charged spinning solution B;

[0263] A hexadecyltrimethylammonium bromide aqueous solution was added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a positively charged spinning solution A; wherein the volume percentage of the hexadecyltrimethylammonium bromide aqueous solution relative to the CUR@β-CD ICs / CS / PLA spinning solution was 2%;

[0264] A negatively charged aqueous solution of metal nanoparticles was added to a zein spinning solution to obtain a negatively charged spinning solution B; wherein the volume percentage of the negatively charged aqueous solution of metal nanoparticles relative to the zein spinning solution was 2%.

[0265] (6) Preparation of chitosan / polylactic acid nanofiber membrane;

[0266] Chitosan and polylactic acid were added to a mixed solution of dichloromethane and N,N-dimethylformamide to obtain a spinning solution. Chitosan / polylactic acid nanofiber membranes were prepared using a dual-needle parallel electrospinning method. The mass ratio of chitosan to polylactic acid was 90:10; the total mass / volume percentage of chitosan and polylactic acid relative to the mixed solution of dichloromethane and N,N-dimethylformamide was 7%; and the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solution was 7:3.

[0267] The electrospinning process parameters are as follows: voltage is 22kV, needle size is 22G, distance between positive and negative electrodes is 20cm, spinning speed is 1.7mL / h, roller speed is 200rpm, spinning ambient temperature is 25℃, and ambient humidity is 40% RH.

[0268] (7) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0269] Using the chitosan / polylactic acid nanofiber membrane obtained in step (6) as the receiving substrate, a double-needle parallel electrospinning method was used to spin the positively charged spinning solution A and the negatively charged spinning solution B obtained in step (4) to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane on both sides of the receiving substrate. Then, after vacuum drying, heat treatment and shaping and cutting, a slow-release antibacterial fiber membrane based on the Janus structure was obtained. The heat treatment temperature was 160℃ and the time was 15min.

[0270] The spinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 22kV, needle specification 20G, distance between positive and negative electrodes 20cm, spinning speed 1mL / h, roller speed 200rpm, spinning ambient temperature 25℃, and ambient humidity 40% RH.

[0271] The spinning process parameters for the corn glycerin membrane are as follows: voltage 22kV, needle size 20G, distance between positive and negative electrodes 20cm, spinning speed 1mL / h, roller speed 200rpm, spinning ambient temperature 25℃, and ambient humidity 40%RH.

[0272] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 70 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, a thickness of 180 μm for the zein membrane, and a thickness of 294 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 50.4%, a tensile strength of 8.2 MPa, and a water vapor permeability of 7.2 × 10⁻⁶. -11g / ms Pa, oxygen permeability 7.5×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 10 CFU, and the bacterial count of *Staphylococcus aureus* was 12 CFU. The inhibition rate of *E. coli* was 98.57%, and the inhibition rate of *Staphylococcus aureus* was 98.29%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.11 L / cm³. 2 The release rate of curcumin in the zein membrane was 0.06 L / cm. 2 .

[0273] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0274] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0275] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 12.04%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0276] Example 6

[0277] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0278] (1) Preparation of raw materials;

[0279] β-Cyclodextrin;

[0280] water;

[0281] Curcumin;

[0282] Ethanol;

[0283] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0284] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0285] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0286] PEDOT:PSS: Manufacturer is Saen Chemical Technology (Shanghai) Co., Ltd., CAS No. 155090-83-8, Product No. A68291;

[0287] Zinc foil;

[0288] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0289] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 30 °C for 2.7 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 0.95:1.

[0290] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) are added to an aqueous acetic acid solution with a volume concentration of 60% and heated and stirred at 50°C for 6 hours to obtain the CUR@β-CD ICs / CS / PLA spinning solution; wherein, the total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid is 16% by mass / volume relative to the acetic acid solution, and based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 5%, the mass percentage of chitosan is 85% and the mass percentage of polylactic acid is 10%;

[0291] (3) Preparation of corn glycidol spinning solution;

[0292] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 7, and the solution was heated and stirred at 60°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 5%;

[0293] (4) Prepare positively charged spinning solution C and positively charged spinning solution D;

[0294] (4.1) Dissolve PEDOT:PSS powder in water heated to 60°C by ultrasound to obtain a positively charged solution with a concentration of 1 mM;

[0295] (4.2) The positively charged solution obtained in step (4.1) is added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a positively charged spinning solution C; wherein the volume percentage of the positively charged solution relative to the CUR@β-CD ICs / CS / PLA spinning solution is 1.5%;

[0296] (4.3) The positively charged solution obtained in step (4.1) is added to the zein spinning solution to obtain a positively charged spinning solution D; wherein the volume percentage of the positively charged solution relative to the zein spinning solution is 1.5%;

[0297] (5) Preparation of petal-shaped nano-ZnO fiber membranes;

[0298] (5.1) Use 1M hydrochloric acid to treat a sample with dimensions of 1cm × 1c m The zinc foil is cleaned to remove the passive oxide layer on the zinc foil, and then thoroughly rinsed with deionized water (DI);

[0299] (5.2) Stir a 2M aqueous solution of (NH4)2SO4 and a 0.1M aqueous solution of ZnSO4 in a magnetic stirrer for 20 minutes to ensure uniform mixing. Then add a 1M aqueous solution of NaOH and continue stirring for 10 minutes to adjust the pH to 7.5, ensuring that the electrodeposition process is in a slightly alkaline state, which is the electrolyte. The mass ratio of (NH4)2SO4, ZnSO4 and NaOH is 16.4:1:2.5.

[0300] (5.3) The electrolyte was placed in an electrodeposition tank, and zinc foil was placed as the working electrode and platinum rod as the counter electrode for electrodeposition. The distance between the two electrodes was 1 cm. Finally, the deposited film was removed from the tank, thoroughly washed with deionized water, and dried in a vacuum oven for 24 hours to obtain a petal-shaped nano-ZnO fiber membrane. The electrodeposition current density was 0.5 A cm⁻¹. -2 ;

[0301] (6) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0302] Using a petal-shaped nano-ZnO fiber membrane as the receiving substrate, a needle-free electrospinning method was employed to spun positively charged spinning solution C and positively charged spinning solution D onto both sides of the receiving substrate to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane. These membranes were then vacuum dried, heat-treated, and shaped and cut to obtain a Janus-structure-based sustained-release antibacterial fiber membrane. The heat treatment temperature was 150℃, and the time was 15 min.

[0303] The needle-free electrospinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membranes are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets 10cm, collection distance 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0304] The needle-free electrospinning process parameters for corn glycerin membrane are as follows: coil spinneret length 20cm, diameter 8cm, applied voltage 55kV, distance between coil spinnerets 10cm, collection distance 25cm, and production line speed 0.2m / min. -1 The coil speed is 15 rpm, the spinning zone temperature is room temperature, and the humidity is maintained at 30% RH.

[0305] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 68 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, 153 μm for the zein membrane, and 237 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 53.2%, a tensile strength of 8.3 MPa, and a water vapor permeability of 7.9 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 7.6×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 10 CFU, and the bacterial count of *Staphylococcus aureus* was 8 CFU. The inhibition rate of *E. coli* was 98.57%, and the inhibition rate of *Staphylococcus aureus* was 98.99%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.13 nL / cm. 2 The release rate of curcumin from the zein membrane was 0.08 nL / cm. 2 .

[0306] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0307] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0308] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 13%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0309] Example 7

[0310] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0311] (1) Preparation of raw materials;

[0312] β-Cyclodextrin;

[0313] water;

[0314] Curcumin;

[0315] Ethanol;

[0316] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56 H 103 N9O 39 ;

[0317] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0318] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0319] PEDOT:PSS: Manufacturer is Saen Chemical Technology (Shanghai) Co., Ltd., CAS No. 155090-83-8, Product No. A68291;

[0320] Zinc foil;

[0321] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0322] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 32 °C for 2 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 0.98:1.

[0323] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) were added to an aqueous acetic acid solution with a volume concentration of 60% and heated and stirred at 55°C for 4 hours to obtain the CUR@β-CD ICs / CS / PLA spinning solution; wherein, the total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid relative to the acetic acid solution was 18% by mass / volume, and based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex was 5%, the mass percentage of chitosan was 90% and the mass percentage of polylactic acid was 5%;

[0324] (3) Preparation of corn glycidol spinning solution;

[0325] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 6, and the solution was heated and stirred at 50°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 3%;

[0326] (4) Prepare positively charged spinning solution C and positively charged spinning solution D;

[0327] (4.1) Dissolve PEDOT:PSS powder in water heated to 60°C by ultrasound to obtain a positively charged solution with a concentration of 1 mM;

[0328] (4.2) The positively charged solution obtained in step (4.1) is added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a positively charged spinning solution C; wherein the volume percentage of the positively charged solution relative to the CUR@β-CD ICs / CS / PLA spinning solution is 1%;

[0329] (4.3) The positively charged solution obtained in step (4.1) is added to the zein spinning solution to obtain a positively charged spinning solution D; wherein the volume percentage of the positively charged solution relative to the zein spinning solution is 1.7%;

[0330] (5) Preparation of petal-shaped nano-ZnO fiber membranes;

[0331] (5.1) Use 1M hydrochloric acid to treat a sample with dimensions of 1cm × 1c m The zinc foil is cleaned to remove the passive oxide layer on the zinc foil, and then thoroughly rinsed with deionized water (DI);

[0332] (5.2) Stir a 2M aqueous solution of (NH4)2SO4 and a 0.1M aqueous solution of ZnSO4 in a magnetic stirrer for 20 minutes to ensure uniform mixing. Then add a 1M aqueous solution of NaOH and continue stirring for 10 minutes to adjust the pH to 8, so as to ensure that the electrodeposition process is in a slightly alkaline state, which is the electrolyte. The mass ratio of (NH4)2SO4, ZnSO4 and NaOH is 16.4:1:2.5.

[0333] (5.3) The electrolyte was placed in an electrodeposition tank, and zinc foil was placed as the working electrode and platinum rod as the counter electrode for electrodeposition. The distance between the two electrodes was 1 cm. Finally, the deposited film was removed from the tank, thoroughly washed with deionized water, and dried in a vacuum oven for 24 hours to obtain a petal-shaped nano-ZnO fiber membrane. The electrodeposition current density was 0.5 A cm⁻¹. -2 ;

[0334] (6) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0335] Using a petal-shaped ZnO nanofiber membrane as the receiving substrate, a dual-needle parallel electrospinning method was employed to spun positively charged spinning solution C and positively charged spinning solution D onto both sides of the receiving substrate, forming a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane. These membranes were then vacuum dried, heat-treated, and shaped and cut to obtain a Janus-structure-based sustained-release antibacterial fiber membrane. The heat treatment temperature was 120℃, and the time was 10 min.

[0336] The spinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 22kV, needle specification 20G, distance between positive and negative electrodes 18cm, spinning speed 0.8mL / h, roller speed 200rpm, spinning ambient temperature 22℃, and ambient humidity 30%RH.

[0337] The spinning process parameters for the corn glycerin membrane are as follows: voltage 16kV, needle specification 20G, distance between positive and negative electrodes 15cm, spinning speed 0.5mL / h, roller speed 200rpm, spinning ambient temperature 22℃, and ambient humidity 30%RH.

[0338] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 65 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, a thickness of 135 μm for the zein membrane, and a thickness of 218 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 55.7%, a tensile strength of 7.8 MPa, and a water vapor permeability of 8.2 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 6.8×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 13 CFU, and the bacterial count of *Staphylococcus aureus* was 10 CFU. The inhibition rate of *E. coli* was 98.14%, and the inhibition rate of *Staphylococcus aureus* was 98.74%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.15 nL / cm. 2 The release rate of curcumin from the zein membrane was 0.12 nL / cm. 2 .

[0339] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0340] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0341] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 12%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

[0342] Example 8

[0343] A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, comprising the following steps:

[0344] (1) Preparation of raw materials;

[0345] β-Cyclodextrin;

[0346] water;

[0347] Curcumin;

[0348] Ethanol;

[0349] Chitosan: Manufacturer is Shanghai Maclean Biochemical Technology Co., Ltd., CAS number is 9012-76-4, molecular formula is C 56H 103 N9O 39 ;

[0350] Polylactic acid: Manufacturer is Ron Reagent Network, CAS number is 2610-05-16, weight average molecular weight is 80000;

[0351] Zeolite: Manufacturer: Shanghai Bid Pharmaceutical Technology Co., Ltd., CAS No.: 9010-66-6, Product No.: BD157001;

[0352] PEDOT:PSS: Manufacturer is Saen Chemical Technology (Shanghai) Co., Ltd., CAS No. 155090-83-8, Product No. A68291;

[0353] Zinc foil;

[0354] (2) Preparation of CUR@β-CD ICs / CS / PLA spinning solution;

[0355] (2.1) β-Cyclodextrin was dissolved in water to prepare a 1 wt% β-cyclodextrin aqueous solution, and curcumin was dissolved in ethanol to prepare a 10 mg / mL curcumin ethanol solution. Then, the curcumin ethanol solution was added to the β-cyclodextrin aqueous solution, and the mixture was stirred at 35 °C for 2.5 h. After that, the mixture was frozen and centrifuged to obtain the inclusion complex powder. Excess impurities were washed away to obtain the curcumin / β-cyclodextrin inclusion complex. The molar ratio of curcumin to β-cyclodextrin was 1.02:1.

[0356] (2.2) The curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid obtained in step (2.1) are added to an aqueous acetic acid solution with a volume concentration of 60% and heated and stirred at 60°C for 5 hours to obtain the CUR@β-CD ICs / CS / PLA spinning solution; wherein, the total amount of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid is 20% by mass / volume relative to the acetic acid solution, and based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 2%, the mass percentage of chitosan is 90% and the mass percentage of polylactic acid is 8%;

[0357] (3) Preparation of corn glycidol spinning solution;

[0358] Zeat protein was added to a 70% (v / v) aqueous acetic acid solution, the pH was adjusted to 5, and the solution was heated and stirred at 55°C for 1 hour to obtain a zeat protein spinning solution; wherein the mass / volume percentage of zeat protein relative to the acetic acid solution was 1%;

[0359] (4) Prepare positively charged spinning solution C and positively charged spinning solution D;

[0360] (4.1) Dissolve PEDOT:PSS powder in water heated to 60°C by ultrasound to obtain a positively charged solution with a concentration of 1 mM;

[0361] (4.2) The positively charged solution obtained in step (4.1) is added to the CUR@β-CD ICs / CS / PLA spinning solution to obtain a positively charged spinning solution C; wherein the volume percentage of the positively charged solution relative to the CUR@β-CD ICs / CS / PLA spinning solution is 2%;

[0362] (4.3) The positively charged solution obtained in step (4.1) is added to the zein spinning solution to obtain a positively charged spinning solution D; wherein the volume percentage of the positively charged solution relative to the zein spinning solution is 2%;

[0363] (5) Preparation of petal-shaped nano-ZnO fiber membranes;

[0364] (5.1) Use 1M hydrochloric acid to treat a sample with dimensions of 1cm × 1c m The zinc foil is cleaned to remove the passive oxide layer on the zinc foil, and then thoroughly rinsed with deionized water (DI);

[0365] (5.2) Stir a 2M aqueous solution of (NH4)2SO4 and a 0.1M aqueous solution of ZnSO4 in a magnetic stirrer for 20 minutes to ensure uniform mixing. Then add a 1M aqueous solution of NaOH and continue stirring for 10 minutes to adjust the pH to 9.5, ensuring that the electrodeposition process is in a slightly alkaline state, which is the electrolyte. The mass ratio of (NH4)2SO4, ZnSO4 and NaOH is 16.4:1:2.5.

[0366] (5.3) The electrolyte was placed in an electrodeposition tank, and zinc foil was placed as the working electrode and platinum rod as the counter electrode for electrodeposition. The distance between the two electrodes was 1 cm. Finally, the deposited film was removed from the tank, thoroughly washed with deionized water, and dried in a vacuum oven for 24 hours to obtain a petal-shaped nano-ZnO fiber membrane. The electrodeposition current density was 0.5 A cm⁻¹. -2 ;

[0367] (6) Preparation of a sustained-release antibacterial fiber membrane based on the Janus structure;

[0368] Using a petal-shaped ZnO nanofiber membrane as the receiving substrate, a dual-needle parallel electrospinning method was employed to spun positively charged spinning solution C and positively charged spinning solution D onto both sides of the receiving substrate to form a CUR@β-CD ICs / CS / PLA nanofiber membrane and a zein membrane. These membranes were then vacuum dried, heat-treated, and shaped and cut to obtain a Janus-structure-based sustained-release antibacterial fiber membrane. The heat treatment temperature was 160℃, and the time was 13 min.

[0369] The spinning process parameters for CUR@β-CD ICs / CS / PLA nanofiber membrane are as follows: voltage 16kV, needle specification 20G, distance between positive and negative electrodes 15cm, spinning speed 0.5mL / h, roller speed 200rpm, spinning ambient temperature 24℃, and ambient humidity 28% RH.

[0370] The spinning process parameters for the corn glycerin membrane are as follows: voltage 18kV, needle specification 20G, distance between positive and negative electrodes 20cm, spinning speed 0.8mL / h, roller speed 200rpm, spinning ambient temperature 25℃, and ambient humidity 28%RH.

[0371] The final Janus-structured sustained-release antibacterial fiber membrane had a thickness of 80 μm for the CUR@β-CD ICs / CS / PLA nanofiber membrane, 186 μm for the zein membrane, and 275 μm for the chitosan / polylactic acid nanofiber membrane. The Janus-structured sustained-release antibacterial fiber membrane exhibited an elongation at break of 52.4%, a tensile strength of 9.2 MPa, and a water vapor permeability of 7.5 × 10⁻⁶. -11 g / ms Pa, oxygen permeability 7.4×10 -5 g / m 2 The bacterial count of *Escherichia coli* was 12 CFU, and the bacterial count of *Staphylococcus aureus* was 11 CFU. The inhibition rate of *E. coli* was 98.29%, and the inhibition rate of *Staphylococcus aureus* was 98.61%. The release amount of curcumin in the CUR@β-CD ICs / CS / PLA nanofiber membrane was 0.11 nL / cm. 2 The release rate of curcumin in the zein membrane was 0.1 nL / cm. 2 .

[0372] The slow-release antibacterial fiber membrane based on the Janus structure prepared above can be used for food preservation.

[0373] To verify the preservation performance of the Janus-based slow-release antibacterial fiber membrane, fresh potatoes were first cut into 3cm×1cm×3cm pieces, then pretreated under ultraviolet light for 1 hour, and then packaged using the Janus-based slow-release antibacterial fiber membrane and stored at room temperature for 4 days.

[0374] The above tests show that the weight loss rate of potatoes preserved using Janus-based slow-release antibacterial fiber membranes was 15%, indicating that Janus-based slow-release antibacterial fiber membranes can reduce the loss of moisture from fresh fruits and vegetables inside the packaging, thereby delaying moisture loss and maintaining freshness.

Claims

1. A method for preparing a sustained-release antibacterial fiber membrane based on the Janus structure, characterized in that: Using a petal-shaped nano-ZnO fiber membrane as the receiving substrate, a positively charged spinning solution C and a positively charged spinning solution D are spun together to obtain an electrospun fiber membrane by using a double-needle parallel electrospinning or needleless electrospinning method. The electrospun fiber membrane is then vacuum dried, heat-treated, and shaped and cut to obtain a slow-release antibacterial fiber membrane based on the Janus structure. The petal-shaped nano-ZnO fiber membrane was prepared by electrochemical deposition using zinc foil as a substrate. The electrolyte used in electrochemical deposition is a mixture of (NH4)2SO4 solution, ZnSO4 solution and NaOH solution, with a pH value of 7.5~9.5; Positively charged spinning solution C is obtained by adding a positively charged solution to the CUR@β-CD ICs / CS / PLA spinning solution, and positively charged spinning solution D is obtained by adding a positively charged solution to the zein spinning solution. The positively charged spinning solution C and the positively charged spinning solution D are solutions with a concentration of 1 mM obtained by dissolving PEDOT:PSS powder in water. In the positively charged spinning solution C, the volume percentage of the positively charged solution relative to the CUR@β-CD ICs / CS / PLA spinning solution is 1~2%; in the positively charged spinning solution D, the volume percentage of the positively charged solution relative to the zein spinning solution is 1~2%. The CUR@β-CD ICs / CS / PLA spinning solution is obtained by dissolving curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid in a solvent.

2. The method for preparing a sustained-release antibacterial fiber membrane based on a Janus structure according to claim 1, characterized in that, The specific preparation process of CUR@β-CDICs / CS / PLA spinning solution is as follows: Curcumin / β-cyclodextrin inclusion complex, chitosan and polylactic acid are added to an acetic acid solution with a volume concentration of 60%, and heated and stirred at 50~60℃ for 4~6h to obtain CUR@β-CDICs / CS / PLA spinning solution; The total amount of curcumin / β-cyclodextrin inclusion complex, chitosan, and polylactic acid relative to the acetic acid solution is 16-20% by mass / volume. Based on the total mass of curcumin / β-cyclodextrin inclusion complex, chitosan, and polylactic acid, the mass percentage of curcumin / β-cyclodextrin inclusion complex is 2-5%, the mass percentage of chitosan is 85-90%, and the mass percentage of polylactic acid is 5-10%.

3. The method for preparing a sustained-release antibacterial fiber membrane based on a Janus structure according to claim 1, characterized in that, The specific preparation process of the zein spinning solution is as follows: zein is added to a 70% acetic acid solution, the pH value is adjusted to 5-7, and the solution is heated and stirred at 50-60℃ for 1 hour to obtain the zein spinning solution. The mass / volume percentage of zein relative to the acetic acid solution is 1-5%.

4. The application of the Janus-based sustained-release antibacterial fiber membrane prepared by the preparation method according to any one of claims 1 to 3, characterized in that: Used for food preservation.

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