Degradable anti-biofilm material and preparation method thereof

Abstract

The invention discloses a degradable anti-biofilm material and a preparation method thereof, and belongs to the field of food packaging materials. The invention provides a degradable anti-biofilm material and application thereof, gallnut extract is added into a gelatin film, hydroxypropyl-beta-cyclodextrin is used for embedding to form microcapsules, epsilon-polylysine is cross-linked by a cross-linking method, and the degradable anti-biofilm material is prepared. According to the preparation method disclosed by the invention, the application blank that the gallnut extract and other substances play a synergistic effect together is filled, and the application of the gallnut extract is further widened.

Description

Technical Field

[0001] The invention relates to a degradable anti-biological film material and a preparation method thereof, belonging to the field of food packaging materials. Background Art

[0002] Food safety problems caused by microorganisms have a serious impact on human health. Studies have shown that most microorganisms exist in the form of biofilms, which form complex communities through the large-scale aggregation of microbial cells and adhesion with extracellular secretions, and are widely present on the surface of food. Biofilms are extremely harmful in the food industry. Microorganisms can easily form biofilms on food processing equipment (such as heat exchangers) or closed surfaces (such as pipelines), which give microorganisms strong environmental adaptability. Not only are they difficult to eliminate, causing equipment corrosion or pipeline blockage, seriously affecting food production efficiency; they can also easily cause secondary contamination of food, accelerate food spoilage, and greatly shorten the shelf life of products.

[0003] In the current food industry or food science research, in order to reduce and eliminate the hazards of biofilms, disinfectants, ultraviolet radiation and ultrasound are often used to kill microbial cells. Although they can achieve a good sterilization effect, they cannot fundamentally solve the hazards of biofilms. Sublethal or re-contaminated microbial cells can still adhere to the surface of food processing-related materials to form new biofilms, leading to a new round of food safety problems. Therefore, modifying food processing-related materials and developing targeted anti-biofilm materials can reduce the attachment of microorganisms from the root and prevent the formation of biofilms. It can not only reduce the hazards of microorganisms in the food industry, but also help control cross-contamination problems in food production and processing. It has very important practical significance for ensuring food safety and promoting the healthy and sustainable development of the food industry.

[0004] Galla Chinensis extract (GC) has good antibacterial activity and inhibits microbial quorum sensing, but its volatility, water insolubility and obvious aromatic odor limit its application in food. Cyclodextrin is a food additive commonly used in food processing to embed fat-soluble or flavor substances. It has a cone-shaped structure with a cavity in the middle, and has the properties of hydrophobic inside and hydrophilic outside. β-cyclodextrin is the only cyclodextrin that is currently mass-produced and widely used in industry due to its high cost-effectiveness, but the solubility of β-cyclodextrin in water is limited due to intramolecular hydrogen bonds, and the hemolytic effect of β-cyclodextrin limits its application.

[0005] At present, there is an existing technology for preparing packaging films using gelatin and gallnut extracts. For example, patent CN116217985B discloses the use of gelatin and essential oils to prepare antibacterial packaging films; patent CN111234324B discloses the use of chitosan and gallnut tannins to prepare antibacterial packaging films. The above patents use pure gelatin or a simple compound of gelatin and other polymers to prepare packaging films, which do not show a significant effect of inhibiting the formation of biofilms, and have little effect on extending the shelf life of food. At the same time, the astringency problem of gallnut tannins has not been solved, which has great defects in practical applications.

[0006] Therefore, preparing a degradable packaging film based on gelatin that can affect microbial quorum sensing to inhibit biofilm formation, has strong mechanical properties, and can avoid the irritating odor of gallnut extract has high practical and economic value. Summary of the invention

[0007] In order to solve the above problems, the present invention prepares a degradable anti-biofilm material, by adding gallnut extract (GC) into gelatin film and using hydroxypropyl-β-cyclodextrin (HPCD) for embedding, the degradable anti-biofilm material is prepared, in the form of microcapsules, the delayed release of gallnut extract is achieved, and the material is given antibacterial and antioxidant activity, and the shelf life of food is extended; on this basis, a safe and non-toxic natural antibacterial product ε-polylysine is added, and the gallnut extract and ε-polylysine play a synergistic antibacterial effect. The present invention fills the application gap of gallnut extract and further broadens the application of gallnut extract.

[0008] The first object of the present invention is to provide a method for preparing a degradable anti-biofilm material, the method comprising the steps of:

[0009] (1) Preparation of inclusion compound

[0010] A hydroxypropyl-β-cyclodextrin aqueous solution is prepared and mixed with a gallnut extract ethanol solution to obtain a mixture solution; the mixture solution is filtered and dried to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex;

[0011] (2) Preparation of Nanoparticles

[0012] The gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex prepared in step (1) is taken to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex solution, sodium tripolyphosphate is added, and the mixture is mixed; a polylysine solution is then added, the mixture is mixed to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion, and the mixture is dried to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle;

[0013] (3) Preparation of degradable anti-biofilm materials

[0014] The gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticles, glycerol, gelatin and water are mixed to obtain a film-forming solution; the film-forming solution is cast into a film to prepare a degradable anti-biofilm material.

[0015] In one embodiment, the substrate is immersed in a film-forming solution and dried to prepare a degradable anti-biofilm material on the surface of the substrate.

[0016] In one embodiment, the degradable anti-biofilm material is a film or a coating.

[0017] In one embodiment, the mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract in the mixture solution of step (1) is 1:1-8;

[0018] Preferably, the mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract is 1:2-6.

[0019] In one embodiment, in the gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion of step (2), the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion compound to polylysine is 5 to 15:1;

[0020] Preferably, the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex to polylysine is 8 to 12:1.

[0021] In one embodiment, the mass fraction of gelatin in the film-forming solution of step (3) is 1-4%, and the mass fraction of glycerol is 1-2%.

[0022] In one embodiment, the stirring in step (1) and step (2) is 100 to 500 r / min for 12 to 24 hours.

[0023] In one embodiment, the stirring in step (3) is 100-200 r / min for 60-120 min.

[0024] In one embodiment, the drying in step (2) is freeze drying for 3 to 5 days.

[0025] In one embodiment, the casting of the film in step (3) includes drying at 30° C. to 35° C. for 12-36 hours.

[0026] In one embodiment, the method for preparing the ethanol solution of the Chinese nut extract comprises the following steps:

[0027] (1) crushing the gallnut in a high-speed crusher for 2 to 10 minutes to obtain gallnut powder; placing the gallnut powder in water at a dosage ratio of 1 g: 1 to 5 mL, extracting at 60 to 90° C. for 1 to 3 hours, and repeating the extraction 1 to 3 times to obtain a gallnut water extract;

[0028] (2) filtering the Galla chinensis water extract to obtain a filtrate, and drying to obtain a Galla chinensis water extract concentrate;

[0029] (3) The concentrated Galla chinensis water extract is dissolved in anhydrous ethanol to prepare an ethanol solution of the Galla chinensis extract.

[0030] The second object of the present invention is to provide a degradable anti-biofilm material prepared by any of the above methods.

[0031] The third object of the present invention is to provide a product, which contains the above-mentioned degradable anti-biofilm material.

[0032] In one embodiment, the product comprises a packaging material, a wearable material, or a degradable material.

[0033] In one embodiment, the packaging material is used to package fruits, vegetables and fresh food, which can extend the shelf life of the fruits, vegetables and fresh food.

[0034] The fourth object of the present invention is to provide the use of the above-mentioned degradable anti-biofilm material or the above-mentioned product in the preparation of food, medicine, agricultural products or textiles.

[0035] A fifth object of the present invention is to provide a method for improving the mechanical strength and antibacterial properties of a gelatin packaging film, wherein the gelatin packaging film is prepared using a gallnut extract, hydroxypropyl-β-cyclodextrin and polylysine, and the preparation method of the gelatin packaging film comprises the following steps:

[0036] (1) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin Inclusion Complex

[0037] A hydroxypropyl-β-cyclodextrin aqueous solution is prepared and mixed with a gallnut extract ethanol solution to obtain a mixture solution; the mixture solution is filtered and dried to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex;

[0038] (2) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin-Polylysine Nanoparticles

[0039] The gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex prepared in step (1) is taken to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex solution, sodium tripolyphosphate is added, and the mixture is mixed; a polylysine solution is then added, the mixture is mixed to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion, and the mixture is dried to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle;

[0040] (3) Preparation of composite membranes with improved mechanical strength and antibacterial properties

[0041] The gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticles, glycerol, gelatin and water are mixed to obtain a film-forming solution, which is cast into a film to prepare a composite film with improved mechanical strength and antibacterial properties.

[0042] In one embodiment, the mass ratio of hydroxypropyl-β-cyclodextrin to the gallnut extract in the mixture solution of step (1) is 1:1-8;

[0043] Preferably, the mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract is 1:2-6;

[0044] In the gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion of step (2), the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion compound to polylysine is 5 to 15:1;

[0045] Preferably, the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex to polylysine is 8 to 12:1;

[0046] The mass fraction of gelatin in the film-forming solution of step (3) is 1-4%, and the mass fraction of glycerol is 1-2%.

[0047] A sixth object of the present invention is to provide a method for preparing a gallnut extract gelatin antibacterial composite film, the method comprising:

[0048] (1) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin Inclusion Complex

[0049] A hydroxypropyl-β-cyclodextrin aqueous solution is prepared and mixed with a gallnut extract ethanol solution to obtain a mixture solution; the mixture solution is filtered and dried to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex;

[0050] (2) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin-Polylysine Nanoparticles

[0051] The gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex prepared in step (1) is taken to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex solution, sodium tripolyphosphate is added, and the mixture is mixed; a polylysine solution is then added, the mixture is mixed to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion, and the mixture is dried to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle;

[0052] (3) Preparation of composite membranes with improved mechanical strength and antibacterial properties

[0053] The gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticles, glycerol, gelatin and water are mixed to obtain a film-forming solution, which is cast into a film to prepare a composite film with improved mechanical strength and antibacterial properties.

[0054] In one embodiment, the mass ratio of hydroxypropyl-β-cyclodextrin to the gallnut extract in the mixture solution of step (1) is 1:1-8;

[0055] Preferably, the mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract is 1:2-6;

[0056] In the gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion of step (2), the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion compound to polylysine is 5 to 15:1;

[0057] Preferably, the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex to polylysine is 8 to 12:1;

[0058] The mass fraction of gelatin in the film-forming solution of step (3) is 1-4%, and the mass fraction of glycerol is 1-2%.

[0059] Beneficial Effects

[0060] The present invention provides a degradable anti-biofilm material and application thereof. The gallnut extract is added into a gelatin film, hydroxypropyl-β-cyclodextrin is used for embedding to form microcapsules, and ε-polylysine is cross-linked by a cross-linking method to prepare a degradable film with good ductility, excellent antibacterial property, good thermal stability, anti-biofilm and no irritating odor. The present invention fills the application gap of the gallnut extract and other substances exerting a synergistic effect together, and further broadens the application of the gallnut extract.

[0061] Specific:

[0062] (1) The present invention uses HPCD, which is safer and has better thermal stability than the commonly used embedding material β-CD, to embed the poorly soluble gallnut extract, thereby achieving a green and pollution-free sustained release method and masking the odor of the gallnut extract. In addition, the structure preparation method is low in cost and simple to operate, and can be prepared by a simple stirring and drying method;

[0063] (2) The present invention selects safe, non-toxic and broad-spectrum antibacterial ε-polylysine to exert a synergistic antibacterial effect with the gallnut extract. While exerting the same antibacterial effect, the addition amount of the gallnut extract is reduced by 16-32 times, thereby effectively reducing the negative impact of the gallnut extract on the mechanical properties of the film. The obtained gallnut extract composite gelatin bionic packaging film has good ductility, antioxidant properties and antibacterial properties, thus solving the problem that the existing gelatin composite film is difficult to achieve good mechanical properties and antibacterial properties at the same time;

[0064] (3) The raw materials and gelatin used in the present invention have the advantages of being non-toxic, biodegradable, and having good biocompatibility. The prepared degradable composite film can effectively inhibit the biofilm formation of Pseudomonas aeruginosa. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The effect of the mass ratio of GC to HPCD on the inclusion compound yield and GC embedding rate;

[0066] Figure 2 Surface and cross-sectional microstructures of gelatin-based films (A and E: GL, B and F: GL-PL, C and G: GL-GC / HPCD, D and H: GL-GC / HPCD / PL);

[0067] Figure 3 The effect of different additives on film thickness;

[0068] Figure 4 The effects of different additives on the mechanical properties of the film (A: tensile strength, B: elongation at break);

[0069] Figure 5 The effects of different additives on the film barrier properties (A: UV transmittance, B: water vapor transmittance);

[0070] Figure 6 The effect of different additives on the water contact angle of the film;

[0071] Figure 7 Effects of different additives on the thermal stability of the film (A: weight change, B: weight change rate);

[0072] Figure 8Effects of Gallic Acid / Hydroxypropyl-β-cyclodextrin Poly-L-lysine Nanoparticles on the Swarming Motility of Pseudomonas aeruginosa;

[0073] Fig. 9 The effect of different additives on the inhibition of Pseudomonas aeruginosa biofilm in the film. DETAILED DESCRIPTION

[0074] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0075] The instruments involved in the present invention are:

[0076] ELISA reader (Synergy LX, BioTeK Instruments); electric blast drying oven (GZX-9070MBE, Hebei Tianjian Engineering Instrument Co., Ltd.); video optical contact angle meter (OCA15EC, Defei Instrument Co., Ltd., Germany); cold field emission scanning electron microscope (SU8100, Hitachi High-Tech Co., Ltd., Japan); UV-visible spectrophotometer (T 9, Beijing Puxi General Instrument Co., Ltd.); controllable constant temperature and humidity test chamber (Dongguan Huitai Machinery Co., Ltd.); physical property analyzer (TA.XT-Plus, Stable Micro Systems, UK); handheld digital micrometer (Mitutoyo, Spain), freeze dryer (SCIENTZ-10ND, Ningbo Xinzhi Biotechnology Co., Ltd.).

[0077] Source of raw materials:

[0078] Gelatin was purchased from Shanghai Sigma Reagent Co., Ltd.;

[0079] Gallnut and Coptis chinensis were purchased from a local supermarket in Wuxi;

[0080] ε-Poly-lysine (CAS: 25104-18-1) was from Jiangxi Lion Biotechnology Co., Ltd.;

[0081] β-Cyclodextrin and hydroxypropyl-β-cyclodextrin were purchased from Shanghai Aladdin Biological Company.

[0082] Experimental methods:

[0083] The properties of the films prepared in the examples and comparative examples were tested:

[0084] (1) Microstructure determination

[0085] The film was cut into appropriate size, gold-sprayed and observed by field emission scanning electron microscopy.

[0086] (2) Thickness measurement

[0087] The film thickness was measured 8 times at random points on the film using a handheld digital thickness gauge, and the mean ± standard deviation (SD) was taken as the film thickness.

[0088] (3) Mechanical properties measurement

[0089] The mechanical properties of the film were measured using a texture analyzer. The dense and complete film sample was cut into 6 cm × 1 cm strips. A special clamp was used to fix it on the texture analyzer to ensure that the film strip was fully unfolded. The initial grip distance of the instrument was set to 30 mm and the probe movement rate was 1 mm / s. The tensile strength (TS) was calculated using the following formula:

[0090]

[0091] Where Fmax represents the maximum force required to break the sample (N), d represents the sample thickness (mm), and w represents the sample width (mm).

[0092] The elongation at break (EAB) is calculated using the following formula:

[0093]

[0094] Wherein, L1 represents the length of the sample at the moment of fracture (mm), and L0 represents the initial grip distance (mm).

[0095] (4) Barrier performance measurement

[0096] The water vapor permeability (WVP) of the film was measured by gravimetric method. First, the film was cut into 4cm×4cm squares and 5 points were randomly selected. The thickness was measured using a handheld digital thickness meter and the average value was taken. 10mL of ultrapure water was added to a permeable cup (30mm×50mm weighing bottle), and the film sample was sealed at the opening of the permeable cup with a sealing film to ensure that there was no pore leakage, and then placed in a drying dish. The weight of the permeable cup was weighed every 2h. The formula for calculating WVP is as follows:

[0097]

[0098] Wherein, slope A represents the slope calculated from the linear curve of mass change and time, X represents the average thickness of the membrane sample, A represents the opening area of ​​the moisture permeable cup, and ΔP represents the water vapor pressure difference on both sides of the membrane.

[0099] (5) Water contact angle measurement

[0100] The water contact angle (WCA) of the film surface was measured using a water contact angle analyzer: the film sample was cut into a rectangle (2 cm × 2 cm), fixed on a glass slide, and then 10 μL of ultrapure water was dropped onto the film surface to measure its WCA.

[0101] (6) Thermal stability determination

[0102] The film was subjected to thermogravimetric analysis using a TGA thermal analyzer to detect its thermal stability. About 5 mg of the film sample was weighed and placed in the thermal analyzer for testing, with the nitrogen flow rate set to 50 cm3 / min, the heating rate set to 10°C / min, and the temperature range set to 30°C-600°C.

[0103] (7) Inhibition of microbial swarming motility and biofilm by inclusion complexes and films

[0104] Swarming is a flagella-dependent movement that can be observed in a viscous environment. Nanoparticle solutions at concentrations of 100, 50, and 10 μg / mL were added to a culture medium plate (0.8% nutrient broth, 0.5% glucose, 0.5% agar), and the agar medium was air-dried for 5-10 minutes. The culture plates were inoculated with Pseudomonas aeruginosa (PA01) strains and incubated at 30°C for 24 hours. The size of the swarm was determined by measuring the swarm diameter around the inoculation point.

[0105] Biofilm formation was determined according to the method described by O'Toole & Kolter (1998). PA01 cultured overnight in LB medium was diluted 100-fold with fresh LB medium and cultured for another hour. Films with different additives (cut into 2 cm × 2 cm rectangles) were added to the wells of a 24-well polystyrene plate. 2 mL of PA01 suspension (bacterial concentration was 10 6 CFU) were transferred to the wells and incubated at 37°C. After 48 hours of incubation, the LB medium was discarded and the wells were washed twice with phosphate buffered saline (PBS). The cells adhered to the wells were stained with 0.1% crystal violet for 10 minutes and then washed twice with PBS. The cell-bound dye was eluted with 2 mL of 95% ethanol, and the absorbance of the eluted solution was measured at 570 nm using a spectrophotometer.

[0106] (8) Antibacterial ability

[0107] Determination of MIC: The inhibitory activity of different samples against Escherichia coli and Staphylococcus aureus was tested by 2-fold gradient dilution method in 96-well plate.

[0108] First, activate the strain in a constant temperature incubator for 24 hours, and dilute the bacterial solution with LB liquid culture medium to an OD600 value of 0.5. Add 5% (v / v) Tween-80 aqueous solution to the gallnut extract, and the dissolved sample is configured to 4000 mg / L. Take 100 μL of the configured sample and add it to a 96-well plate containing 100 μL of LB liquid culture medium for gradient dilution. After dilution, add 100 μL of bacterial solution to it, use the bacterial solution containing the same volume of Tween-80 as a blank control, and use the same concentration of anhydrous ethanol as a positive control. Repeat each sample concentration three times. After culturing in an incubator at 37°C for 24 hours, observe and use the lowest liquid concentration without turbidity in the wells of the 96-well plate as the MIC value of the sample for the test bacteria.

[0109] MBC determination: After the MIC determination is completed, select (1x, 2x, 4x, 8x) MIC concentrations in a 96-well plate, take 100 μL from them and inoculate them on LB agar plates, and culture them at 37°C for 24 hours. The lowest concentration without microbial growth is the MBC value.

[0110] The freeze-drying conditions in the embodiment are: freeze-drying at -80°C for 72h;

[0111] Unless otherwise specified, the solvent of the solution in this application is deionized water.

[0112] Example 1: Preparation of Galla Chinensis Extract and Galla Chinensis Inclusion Complex

[0113] 1. Prepare the Chinese nut extract by the following steps:

[0114] (1) crushing the gallnut in a high-speed crusher for 5 minutes to obtain gallnut powder; taking 100 g of the gallnut powder and placing it in 500 mL of ultrapure water at 80° C. for 1 hour, and repeating the extraction 3 times to obtain a gallnut water extract;

[0115] (2) vacuum filtering the obtained Galla chinensis aqueous extract using Whatman No. 1 filter paper to obtain a filtrate, and evaporating the filtrate to dryness under vacuum to obtain a Galla chinensis aqueous extract concentrate;

[0116] (3) The concentrated extract of the Chinese nut water extract was dissolved in anhydrous ethanol for subsequent experiments, and filtered using a 0.22 μm filter membrane to prepare a Chinese nut extract (GC) ethanol solution, which was frozen at -20°C and stored for use.

[0117] 2. Prepare the gallnut inclusion compound, the steps are as follows:

[0118] (1) preparing 500 mL of a 7.7-61.6 mg / mL hydroxypropyl-β-cyclodextrin (HPCD) aqueous solution and 500 mL of a 7.7 mg / mL ethanol solution of a gallnut extract (GC); mixing the mixture so that the mass ratio of GC to HPCD is 1:1 to 8;

[0119] (2) The GC ethanol solution was added dropwise into the magnetically stirred HPCD solution (45°C, 300 r / min). After the two were fully mixed, the temperature and stirring rate were kept constant and stirred for 24 h to completely evaporate the ethanol. Then, the mixture was stirred for 12 h at 30°C and 300 r / min in the dark to obtain a mixture solution.

[0120] (3) After stirring, the mixture solution is filtered using a 0.45 μm filter membrane to obtain a filtered gallnut-hydroxypropyl-β-cyclodextrin (GC / HPCD) inclusion complex solution;

[0121] (4) The GC / HPCD inclusion complex solution was frozen at -80°C for 6 h, and then placed in a freeze dryer for freeze drying to obtain a GC / HPCD inclusion complex solid powder.

[0122] Example 2: Characterization of GC / HPCD inclusion complexes

[0123] (1) Determination of GC inclusion rate in GC / HPCD inclusion complex

[0124] Record the mass of HPCD and GC used. After the GC / HPCD inclusion complex is prepared, accurately weigh the mass of the inclusion complex, and calculate the inclusion complex yield using the following formula:

[0125]

[0126] Wherein, M represents the inclusion compound yield (%); m1 represents the mass of HPCD solid powder (g); m2 represents the mass of GC (g); and m3 represents the mass of GC / HPCD inclusion compound (g).

[0127] (2) Determination of GC embedding rate in GC / HPCD inclusion complex

[0128] Using gallic tannin as a representative substance, ultra-high performance liquid chromatography (HPLC) was used to determine the standard curve. A certain amount of GC / HPCD inclusion solid powder was added to a centrifuge tube, and a known volume of anhydrous ethanol was added, sealed, and ultrasonically treated at 65°C for 3.5h. Centrifuge at room temperature (12000r / min) for 15min to extract GC and dissolve it in anhydrous ethanol, filter it with a 0.22μm filter membrane, take the supernatant, and measure it using HPLC. Then analyze and calculate according to the standard curve in, and the GC embedding rate in the GC / HPCD inclusion complex is calculated using the following formula:

[0129]

[0130] Wherein, n1 represents the mass of the embedded gallic tannin (g); n2 represents the mass of the solid powder of the GC / HPCD inclusion complex (g).

[0131] The results of embedding rate and inclusion rate are as follows Figure 1 As shown in the figure, the results show that the effect of the mass ratio of GC to HPCD on the inclusion yield and GC embedding rate shows a trend of first increasing and then decreasing. When the mass ratio of GC to HPCD is 1:4, the inclusion yield and GC embedding rate both reach the highest values, which are 56.12% and 24.36%, respectively. When the mass ratio continues to increase, the inclusion yield and GC embedding rate begin to decrease, which may be due to the excessive GC affecting the embedding process.

[0132] In summary, the best effect is achieved when the mass ratio of GC to HPCD is 1:4, and the subsequent examples all use GC / HPCD prepared with a mass ratio of 1:4.

[0133] Example 3: Preparation of GC / HPCD polylysine nanoparticles

[0134] GC / HPCD polylysine nanoparticles were prepared by ionic crosslinking method, the steps are as follows:

[0135] Take the GC / HPCD inclusion complex solid powder prepared in Example 1 (the mass ratio of GC to HPCD is 1:4), prepare 20.0 mg / mL GC / HPCD inclusion complex aqueous solution, add sodium tripolyphosphate (STPP) to a concentration of 0.5 mg / mL, place it in a magnetic stirrer and stir it at 150 r / min at room temperature (15-30°C) for 60 min to obtain a mixed solution; add ε-PL solution dropwise to the mixed solution to make the ε-PL concentration in the mixed solution reach 2.0 mg / mL, continue stirring for 60 min, and prepare GC / HPCD polylysine nanoparticle emulsion, and freeze-dry the emulsion to prepare GC / HPCD polylysine nanoparticles (GC / HPCD / ε-PL).

[0136] A group in which no GC / HPCD inclusion complex was added to the prepared solution (containing only ε-PL and no STPP treatment was required) was used as a blank control group.

[0137] Example 4: Preparation of degradable anti-biofilm material (gelatin composite film)

[0138] The steps for preparing the degradable anti-biofilm material are as follows:

[0139] 0.4 g of the GC / HPCD / ε-PL prepared in Example 3 was added to 20 mL of a solution containing 1% glycerol and 4% (w / v) gelatin, and stirred at 400 r / min with a magnetic stirrer for 90 min. After complete mixing, the mixture was ultrasonically treated for 10 min for degassing. 10 mL of the solution was poured into a plastic culture dish with a diameter of 90 mm, and dried in a constant temperature and humidity chamber for 36 h. After manual peeling, a degradable anti-biofilm material was obtained, which was named as gallnut extract gelatin antibacterial composite film (abbreviated as GL-GC / HPCD / PL).

[0140] Comparative Example 1: Preparation of membrane using Coptis chinensis extract

[0141] The film (GL-RC / HPCD / PL) of the Rhizoma Coptidis extract was prepared by the following method:

[0142] On the basis of Example 1, the gallnut was replaced by Coptis chinensis to prepare Coptis chinensis-hydroxypropyl-β-cyclodextrin inclusion complex, and the Coptis chinensis gelatin antibacterial composite film was prepared according to the methods of Examples 3 and 4.

[0143] Comparative Example 2: Pure gelatin film

[0144] A pure gelatin film (GL) was prepared by preparing a gelatin solution containing 1% glycerol and 4% (w / v), stirring the solution with a magnetic stirrer at 400 r / min for 90 min; after the gelatin and glycerol were completely mixed, the solution was subjected to ultrasonic treatment for 10 min for degassing, 10 mL of the solution was poured into a plastic culture dish with a diameter of 90 mm, dried in a constant temperature and humidity chamber for 36 h, and the pure gelatin film (GL) was obtained after manual peeling.

[0145] Comparative Example 3: No ε-PL added

[0146] The film without adding ε-PL (GL-GC / HPCD) was prepared by:

[0147] On the basis of Example 4, the GC / HPCD polylysine nanoparticle powder was replaced with the GC / HPCD inclusion compound solid powder prepared in Example 1, keeping the mass of the GC / HPCD polylysine nanoparticle powder and the GC / HPCD inclusion compound solid powder consistent (i.e., 0.36 g), and the other conditions were consistent with Example 4 to prepare a film.

[0148] Comparative Example 4: Only ε-PL was added

[0149] A film containing only ε-PL and gelatin (GL / PL) was prepared by:

[0150] Add 40 mg of ε-PL to 20 mL of a solution containing 1% glycerol and 4% (w / v) gelatin, and stir with a magnetic stirrer at 400 r / min for 90 min. After complete mixing, degasify by ultrasonic treatment for 10 min, take 10 mL of the solution and pour it into a plastic culture dish with a diameter of 90 mm, dry it in a constant temperature and humidity chamber for 36 h, and then manually peel it off to obtain the polylysine gelatin film.

[0151] Comparative Example 5: Preparation of thin film using β-CD

[0152] Based on Example 1, HPCD was replaced with β-CD to prepare the gallnut extract-β-cyclodextrin inclusion complex, and the gallnut extract gelatin antibacterial composite film was prepared according to the methods of Examples 3 and 4, and was named GL-GC / CD / PL. Comparative Example 6: Preparation of thin film using only GC

[0153] To 20 mL of a solution containing 2% glycerol and 8% (w / v) gelatin, add 20 mg of an ethanol solution of 14.4 mg / mL of gallnut extract, and stir with a magnetic stirrer at 400 r / min for 90 min. After complete mixing, degas the solution by ultrasonic treatment for 10 min, take 10 mL of the solution and pour it into a plastic culture dish with a diameter of 90 mm, dry it in a constant temperature and humidity chamber for 36 h, and then manually peel it off to obtain a GC gelatin film.

[0154] The results show that the tensile strength of the film prepared by adding only GC without adding HPCD and PL is too poor and there is a strong pungent odor.

[0155] Example 5: Detection of antibacterial ability of different active substances

[0156] (1) The antibacterial (Escherichia coli, Staphylococcus aureus) properties of Rhizoma Coptidis extract, GC and ε-PL were tested. The results are shown in Table 1.

[0157] The results are shown in Table 1. The results showed that the Coptidis extract and GC had similar antibacterial abilities, while the antibacterial properties of ε-PL against the two bacteria were significantly greater than those of the two Chinese herbal medicine extracts.

[0158] Table 1 MIC and MBC of ε-PL, RC and GC against Staphylococcus aureus and Escherichia coli

[0159]

[0160] (2) Antibacterial effects of GC and ε-PL alone and in combination

[0161] The micro-dilution method was used: 100 μL of ε-PL and GC were diluted horizontally and vertically in a 96-well plate (2×MIC to 1 / 32×MIC), and then 100 μL of bacterial suspension was added and cultured at 37°C for 24 h. The graded inhibition concentration index (FICI) was used to evaluate the synergistic antibacterial effect. The formula is as follows:

[0162] FICI=FIC A +FIC B

[0163] Similarly, replace the above MIC value with the MBC value and repeat the above steps. Calculate the Fractional Bactericidal Concentrations Index (FBCI) to evaluate the synergistic bactericidal effect, the formula is as follows:

[0164] FBCI=FBC A +FBC B

[0165] Where FIC A =MIC A (Combination use of gallnut extract and polylysine) / MIC A (Gallac extract used alone), FIC B =MIC B (Combination use of gallnut extract and polylysine) / MIC B(Using polylysine alone); while FBC A = MBC A (Using the combination of gallnut extract and polylysine) / MBC A (Using gallnut extract alone), FBC B = MBC B (Using the combination of gallnut extract and polylysine) / MBC B (Using polylysine alone). FIC B and FBC B use the same calculation formula. When FICI or FBCI < 0.5, it is a synergistic effect; when 0.5 ≤ FICI or FBCI ≤ 1, it is an additive effect; when 1 < FICI or FBCI ≤ 4, it is an irrelevant effect; and when FICI or FBCI > 4, it is an antagonistic effect.

[0166] The results are shown in Table 2. The results indicate that all FICI and FBCI are less than 0.5, proving that there is an obvious synergistic effect between gallnut extract and polylysine. The films prepared with a high addition amount of GC have problems such as odor irritation and low tensile strength; while when ε-PL / GC is used for the synergistic antibacterial combination, while significantly reducing the addition amount of GC, it can still maintain excellent antibacterial ability. Moreover, with the decrease of the GC addition amount, it means that the addition amount of the active substances of the extract in the film can be reduced without affecting the antibacterial activity, and the irritating odor of the extract will also be weakened, improving the current situation of the limited application of the active ingredients of the extract in the food field.

[0167] Table 2 FICI and FBCI when ε-PL and GC act jointly

[0168]

[0169] Example 6: Determination of film properties

[0170] Take the gallnut extract gelatin antibacterial composite film (GL-GC / HPCD / PL) prepared in Example 4, the films prepared in Comparative Examples 1-6, and the lotus leaf essential oil film (CN117986655B) to detect the film properties.

[0171] (1) Results of determination of film microstructure, thickness and mechanical properties

[0172] The SEM images of the film surface and cross-section are as Figure 2 shown. As can be seen from A and E in Figure 2 , GL with only gelatin added shows a dense and smooth surface and cross-section, indicating that the gelatin matrix network structure is very dense; as can be seen from Figure 2It can be seen from B and F in Figure 1 that after adding ε-PL to gelatin, the surface of the GL-PL film did not change significantly and remained dense, uniform and smooth. Figure 2 It can be seen from C and G in that after adding GC / HPCD to gelatin, the surface of the GL-GC / HPCD membrane presents a granular feel, which is caused by the accumulation during the casting process; the cross-linked structure of the cross section of the GL-PL membrane and the GL-GC / HPCD membrane is more inclined to a "layered" accumulation structure, and the transverse cracks are caused by the stress generated by the scalpel when cutting the membrane; Figure 2 It can be seen from D and H in that after adding GC / HPCD / PL to gelatin, the membrane surface is dense without obvious holes, but slight wrinkles appear. This is caused by the fact that GC / HPCD / PL contains more groups that can interact with gelatin.

[0173] The thickness of the gelatin-based film is an essential indicator for characterizing the mechanical properties of the film. Figure 3 As shown, GL has the smallest thickness of 0.83±0.05 mm. When ε-PL and GC / HPCD are mixed into the gelatin matrix, the film thickness is not significantly affected. However, the addition of GC / HPCD / ε-PL significantly increases the film thickness to 0.97±0.027 mm.

[0174] The mechanical properties of the film are closely related to the intermolecular and intramolecular interactions added to the film-forming matrix. Adding smaller droplets or particles to the film and distributing them evenly can obtain appropriate interaction forces between the droplets or particles, thereby forming a more complete film network structure.

[0175] The results of tensile strength (TS) and elongation at break (EAB) are as follows: Figure 4 As shown in A and B in the figure, the results show that the tensile strength of the gelatin-based film is 58.33±4.28MPa, and the addition of ε-PL and GC / HPCD components will reduce the TS of the gelatin-based film, which are 49.52±5.49MPa and 46.62±2.62MPa, respectively. The tensile strength of GL-GC / HPCD / PL is comparable to that of gelatin film, while the tensile strength of the film prepared using β-CD (GL-GC / β-CD / PL) and the film prepared using Coptis chinensis extract (GL-RC / HPCD / PL) are lower than that of GL-GC / HPCD / PL film.

[0176] Except for the GL-PL film, the EAB of the films was enhanced after adding GC / HPCD, GC / HPCD / ε-PL, GC / β-CD / PL, and RC / HPCD / PL. This is because the added substances provide relatively high surface interactions between gelatin polymer chains, which helps to enhance the transfer of stress from polymer chains to the additives, leading to improved mechanical properties. Among them, the GL-GC / HPCD / PL film has the largest EAB and has better toughness and ductility.

[0177] It can be seen that the GL-GC / HPCD / PL film has good tensile strength and elongation at break.

[0178] (2) Film barrier properties and water contact angle measurement results

[0179] Light transmittance and transparency are the main evaluation indicators of the appearance performance of packaging materials. When ultraviolet light passes through packaging materials, especially ultraviolet light can catalyze the oxidation reaction of photosensitive components in lipid compounds, accelerating food spoilage.

[0180] The transmittance results are as follows Figure 5 As shown in A, the GL film exhibits a barrier effect in the UV-visible region within the wavelength range of 200nm-300nm, with a transmittance between 0.10% and 58.39%, but the transmittance exceeds 85% in the visible wavelength range. Jiulin W et al.'s study in "The preparation, characterization, antimicrobial stability and in vitro release evaluation of fish gelatin films incorporated with cinnamon essential oil nanoliposomes" showed that gelatin-based films have good UV absorption due to the peptide bonds and phenylalanine aromatic residues in the gelatin protein chain. In contrast, the addition of GC / HPCD, GC / HPCD / PL and ε-PL significantly reduced the transmittance of the film in the UV region, especially in the wavelength range of 300nm-500nm, which is mainly attributed to the strong UV absorption ability of GC molecules in this wavelength range.

[0181] The water vapor permeability coefficient is an important indicator reflecting the comprehensive performance of the membrane. The membrane's barrier effect on water vapor helps to provide a stable environment for food.

[0182] Water vapor transmission rate (WVP) results are as follows Figure 5 As shown in Figure B, the results show that the WVP value of GL is 0.323±0.02g·m -1 ·h -1 ·Pa -1The addition of additional components resulted in an increase in the water vapor permeability coefficient of the membrane, which was 0.437±0.014 g·m for GL-PL, GL-GC / HPCD, and GL-GC / HPCD, respectively. -1 ·h -1 ·Pa -1 , 0.451±0.009g·m -1 ·h -1 ·Pa -1 , 0.573±0.014g·m -1 ·h -1 ·Pa -1 There may be two reasons for this result: first, the hydroxyl groups in GC / HPCD interact with water, and the abundant hydroxyl groups on the outer edge of each GC / HPCD molecule increase the water vapor permeability; second, it is related to the cross-linking of the additives and the gelatin matrix. Different cross-linking networks are formed under different interaction forces, resulting in the microstructural differentiation of the gelatin base film. The incorporation of non-gelatin components may increase the porosity of the gelatin matrix. For example, the addition of GC / HPCD and GC / HPCD / ε-PL will expand the spacing of the gelatin matrix and provide channels for water vapor permeation, thereby increasing WVP.

[0183] The water contact angle of the film is Figure 6 As shown in the figure, compared with the GL film (contact angle 82.35°), the water contact angles of the remaining films after adding active substances were significantly improved, among which the GL-GC / HPCD film had the largest contact angle, reaching 118.45°. This may be due to the deposition of cyclodextrin inclusion compound particles on the film surface, which increased the roughness of the film surface. However, there was no significant difference in the water contact angles of the GL-PL film (contact angle 116.34°) and the GL-GC / HPCD / PL film (contact angle 115.32°). The reason is that the PL in the GL-GC / HPCD / PL film is cross-linked on the outside of the cyclodextrin inclusion compound, and the PL is evenly distributed on the surface of both films, showing similar liquid wetting properties.

[0184] It can be seen that the GL-GC / HPCD / PL film has a low light transmittance and good hydrophobicity, while the higher water vapor permeability is suitable for the packaging of some fruits and vegetables with a strong respiration rate, which can better release the generated water vapor and avoid condensation of water vapor to accelerate decay.

[0185] (3) Film thermal stability test results

[0186] Thermal stability results are as follows Figure 7 The weight change and weight change rate results are shown as Figure 7 As shown in A and B in the figure, the results show that with the change of temperature, the TGA curve of the film shows three weight loss stages.

[0187] from Figure 7 From the weight change of A, it can be seen that the first stage occurs at 30℃-200℃, at which time the weight of the film loses about 15%, and the mass loss at this time is mainly due to the loss of water. The second stage occurs at 200℃-350℃. At this stage, the weight loss ratios of different films begin to show obvious differences. The GL film has the highest weight loss (the weight loss ratio is close to 75%), and the weight loss ratios of other composite films are around 70%. The mass loss at this stage is mainly caused by the degradation of proteins, mainly gelatin. In the third stage, the mass change of the film tends to be stable. From the residual mass of the final film, it can be seen that the addition of PL and HPCD significantly improves the thermal stability of the film, while the thermal stability of β-CD is poor. After adding gelatin film, the thermal stability of the film is reduced.

[0188] And from Figure 7 From the weight change rate shown in B, it can be seen that the change rate curves of all films peak at 350°C, when the weight decrease rate is the largest and there is no obvious deviation, proving that the weight change at this time is mainly derived from the decomposition of the film gelatin matrix.

[0189] It can be seen that the GL-GC / HPCD / PL film has good thermal stability.

[0190] (4) Inclusion complexes and films inhibit microbial swarming and biofilm formation

[0191] The antibacterial results of GC / HPCD / ε-PL are as follows Figure 8 As shown, the results showed that with the increasing amount of nanoparticles added, the bacterial aggregation in the culture medium plate continued to decrease, indicating that under the combined action of poly-lysine and gallnut extract inclusion complex, the swarming movement of Pseudomonas aeruginosa was significantly inhibited.

[0192] The results of biofilm inhibition rate are as follows Fig. 9 As shown, the results show that the effect of gallnut extract is better than that of coptis extract in terms of the inhibition rate of Pseudomonas aeruginosa biofilm. When gallnut extract and polylysine are used together, the two exert a synergistic effect, and the ability to inhibit biofilm formation is greatly improved, with an inhibition rate of more than 80%. In addition, the gallnut extract gelatin antibacterial composite film (GL-GC / HPCD / PL) is compared with the lotus leaf essential oil film (GL-LEO / L / CW) in patent CN117986655B, and its inhibitory effect on Pseudomonas aeruginosa biofilm is significantly better than that of lotus leaf essential oil film. Therefore, we can believe that the film has a good ability to resist biofilm formation.

[0193] In summary, the GL-GC / HPCD / PL film has good tensile strength and elongation at break, low transmittance, good hydrophobicity and thermal stability, and excellent anti-biofilm ability.

[0194] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a degradable anti-biofilm material, characterized in that: The method comprises the steps of: (1) Preparation of inclusion compound A hydroxypropyl-β-cyclodextrin aqueous solution is prepared and mixed with a gallnut extract ethanol solution to obtain a mixture solution; the mixture solution is filtered and dried to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex; (2) Preparation of Nanoparticles The gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex prepared in step (1) is taken to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex solution, sodium tripolyphosphate is added, and the mixture is mixed; a polylysine solution is then added, the mixture is mixed to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion, and the mixture is dried to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle; (3) Preparation of degradable anti-biofilm materials Mixing gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticles, glycerol, gelatin and water to obtain a film-forming solution; Casting the film-forming solution into a film to prepare a degradable anti-biofilm material; Optionally, the substrate is immersed in a film-forming solution to prepare a degradable anti-biofilm material on the surface of the substrate.

2. The method according to claim 1, characterized in that The mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract in the mixture solution of step (1) is 1:1-8; Preferably, the mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract is 1:2-6.

3. The method according to claim 1, characterized in that In the gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion of step (2), the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion compound to polylysine is 5 to 15:1; Preferably, the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex to polylysine is 8 to 12:

1.

4. The method according to claim 1, characterized in that: The mass fraction of gelatin in the film-forming solution of step (3) is 1-4%, and the mass fraction of glycerol is 1-2%.

5. The degradable anti-biofilm material prepared by the method according to any one of claims 1 to 4.

6. A product, characterized in that The product contains the degradable anti-biofilm material according to claim 5, and the product comprises a packaging material, a wearable material or a degradable material.

7. Use of the degradable anti-biofilm material according to claim 5 or the product according to claim 6 in the preparation of food, medicine, agricultural products or textiles.

8. A method for improving the mechanical strength and antibacterial properties of gelatin packaging film, characterized in that: A gelatin packaging film is prepared using gallnut extract, hydroxypropyl-β-cyclodextrin and polylysine. The preparation method of the gelatin packaging film comprises the following steps: (1) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin Inclusion Complex A hydroxypropyl-β-cyclodextrin aqueous solution is prepared and mixed with a gallnut extract ethanol solution to obtain a mixture solution; the mixture solution is filtered and dried to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex; (2) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin-Polylysine Nanoparticles The gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex prepared in step (1) is taken to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex solution, sodium tripolyphosphate is added, and the mixture is mixed; a polylysine solution is then added, the mixture is mixed to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion, and the mixture is dried to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle; (3) Preparation of composite membranes with improved mechanical strength and antibacterial properties The gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticles, glycerol, gelatin and water are mixed to obtain a film-forming solution, which is cast into a film to prepare a composite film with improved mechanical strength and antibacterial properties.

9. The method according to claim 8, characterized in that: The mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract in the mixture solution of step (1) is 1:1-8; Preferably, the mass ratio of hydroxypropyl-β-cyclodextrin to the Chinese nut extract is 1:2-6; In the gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion of step (2), the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion compound to polylysine is 5 to 15:1; Preferably, the mass ratio of the gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex to polylysine is 8 to 12:1; The mass fraction of gelatin in the film-forming solution of step (3) is 1-4%, and the mass fraction of glycerol is 1-2%.

10. A method for preparing a gallnut extract gelatin antibacterial composite film, characterized in that: The method comprises: (1) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin Inclusion Complex A hydroxypropyl-β-cyclodextrin aqueous solution is prepared and mixed with a gallnut extract ethanol solution to obtain a mixture solution; the mixture solution is filtered and dried to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex; (2) Preparation of Galla Chinensis Extract-Hydroxypropyl-β-cyclodextrin-Polylysine Nanoparticles The gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex prepared in step (1) is taken to prepare a gallnut extract-hydroxypropyl-β-cyclodextrin inclusion complex solution, sodium tripolyphosphate is added, and the mixture is mixed; a polylysine solution is then added, the mixture is mixed to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle emulsion, and the mixture is dried to obtain a gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticle; (3) Preparation of composite membranes with improved mechanical strength and antibacterial properties The gallnut extract-hydroxypropyl-β-cyclodextrin-polylysine nanoparticles, glycerol, gelatin and water were mixed to obtain a film-forming solution, which was cast into a film to prepare a gallnut extract gelatin antibacterial composite film.

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