Pachymaran antibacterial film as well as preparation method and application thereof

Abstract

The invention relates to the field of polysaccharide antibacterial film preparation, and discloses a pachymaran antibacterial film as well as a preparation method and application thereof, the method comprises the following steps: (1) mixing pachymaran, alkali liquor and optional glycerol to obtain a mixed solution; (2) mixing the mixed solution with a silver salt solution to obtain a nano-silver composite solution; (3) putting the nano-silver composite solution into a culture dish, and drying at 50-70 DEG C for 10-16 hours; the pachymaran is a straight-chain homogeneous polysaccharide formed by connecting beta-D-glucofuranose residues through beta-(1-> 3)-glucosidic bonds; the concentration of the alkali liquor is 0.08 mol / L to 0.2 mol / L. The pachymaran is used as a stabilizer and a reducing agent, and the automatic film-forming property of the pachymaran is utilized, so that the operation of preparing the pachymaran antibacterial film is very simple and convenient, no other chemical reducing agent or cross-linking agent is needed, and the pachymaran antibacterial film is low in cost and environment-friendly; the pachymaran antibacterial film has good antibacterial effect and safety performance, and can be applied to food preservation.

Description

Technical Field

[0001] The invention relates to the technical field of polysaccharide antibacterial film preparation, and in particular to a pachymaran antibacterial film and a preparation method and application thereof. Background Art

[0002] The research on food preservation technology has been a hot topic in recent years. Among them, the food preservation technology of plastic wrap has also received more and more attention. Traditional plastic wrap is often made of petroleum products such as polyethylene and polyvinyl alcohol. Due to its difficult degradation, it is easy to cause environmental problems such as "white pollution". The antibacterial property of food plastic wrap has become an important development direction of food plastic wrap, which can give food a longer shelf life. In this regard, the development of new degradable antibacterial plastic wrap has gradually become the development direction of plastic wrap.

[0003] Polysaccharides have good biodegradability, and polysaccharides are macromolecular carbohydrates formed by connecting multiple monosaccharides through glycosidic bonds. The polyhydroxy structure of polysaccharides enables them to have the effect of green reduction to prepare nanosilver, and the macromolecular polysaccharides act as dispersants to prevent the generated nanosilver particles from aggregating and precipitating. Therefore, the development and application of polysaccharide nanosilver antibacterial film is of great significance to the technical development of antibacterial cling film.

[0004] However, there are two main problems in the preparation of polysaccharide nanosilver antibacterial film: (1) The direct reaction of polysaccharide with silver nitrate is very slow and takes several days; therefore, when using polysaccharide to reduce nanosilver, catalytic means are often used, such as heating, UV irradiation, strong reducing agent addition, etc. Under such conditions, polysaccharide only acts as a dispersant and does not play a reducing role. However, the use of catalytic means makes the preparation of nanosilver more complicated and costly, and may also cause environmental pollution. Too many added ingredients are not easy to remove and cause harm to the human body. (2) When preparing films with polysaccharide as raw material, it is usually necessary to introduce a cross-linking agent (such as glutaraldehyde, aluminum acetate, etc.) or mix several polysaccharides together to form a film through physical and chemical reactions such as cross-linking and electrostatic effects, which makes the preparation process complicated and difficult to control, and may also increase the risk of film toxicity. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems existing in the prior art and provide a tuckahoe polysaccharide antibacterial film with antibacterial performance and good safety performance, as well as a preparation method and application thereof. The tuckahoe polysaccharide antibacterial film uses environmentally friendly and health-friendly raw materials during the preparation process, and the straight-chain tuckahoe polysaccharide can be used as a stabilizer and a reducing agent, thereby solving the problems of large particle size, long time consumption and / or the need to add a strong reducing agent in the preparation of existing nanosilver materials; at the same time, the self-film-forming property of the straight-chain tuckahoe polysaccharide is utilized to prepare the polysaccharide antibacterial film. The method is very simple to operate, does not require the use of any other chemical reducing agent to obtain nanosilver, and does not require the addition of a film-forming agent or a cross-linking agent, etc., has low preparation cost and is environmentally friendly, and the prepared tuckahoe polysaccharide antibacterial film has good mechanical properties and good soil degradation properties.

[0006] In order to achieve the above object, the present invention provides a method for preparing a tuckahoe polysaccharide antibacterial film, which comprises the following steps:

[0007] (1) mixing tuckahoe polysaccharide, alkali solution and optionally glycerol to obtain a mixed solution;

[0008] (2) mixing the mixed solution with a silver salt solution to obtain a nanosilver composite solution;

[0009] (3) placing the nanosilver composite solution in a culture dish and drying it at 50-70° C. for 10-16 hours;

[0010] Wherein, the tuckahoe polysaccharide is a straight-chain uniform polysaccharide formed by β-D-furanose glucose residues connected by β-(1→3)-glycosidic bonds;

[0011] The concentration of the alkali solution is 0.08-0.2 mol / L.

[0012] Preferably, step (1) specifically includes:

[0013] S10, mixing Poria cocos polysaccharide with alkali solution to obtain a polysaccharide solution;

[0014] S20, stirring and mixing the polysaccharide solution and glycerol to obtain a mixed solution;

[0015] Preferably, in step S20, the stirring and mixing conditions include: a temperature of 20 to 25° C., a time of 20 to 60 min, and a stirring speed of 100 to 200 rpm.

[0016] Preferably, the dosage ratio of the tuckahoe polysaccharide to the alkali solution is 60 mg: 0.5-2 mL;

[0017] Preferably, the weight ratio of the glycerol to the pachymaran is 0.1-0.5:1;

[0018] Preferably, the alkali solution is sodium hydroxide solution.

[0019] Preferably, in step (2), the silver salt in the silver salt solution is silver nitrate;

[0020] Preferably, in step (2), the mixing operating conditions include: temperature of 30-40° C., time of 1-4 h, and stirring speed of 100-200 rpm.

[0021] Preferably, the dosage ratio of the tuckahoe polysaccharide to the silver salt in the silver salt solution is 960 mg: 0.005-0.06 mmol;

[0022] Preferably, the concentration of the silver salt solution is 10-30 mmol / L.

[0023] Preferably, the size of the culture dish is 9 to 15 cm, and the amount of the nanosilver composite solution is 7 to 24 mL.

[0024] Preferably, step (3) further comprises: dialyzing the dried film in water until the pH of the system is 6.5 to 7.5.

[0025] Preferably, the method further comprises preparing Pachycory polysaccharide according to the following steps:

[0026] A1. Grinding and sieving the Poria cocos, and then defatting the Poria cocos to obtain a first residue;

[0027] A2, extracting the first residue with brine and filtering it to obtain a second residue;

[0028] A3, extracting the second residue with alkali solution and filtering to obtain a first filtrate;

[0029] A4, deproteinizing and filtering the first filtrate, mixing the obtained second filtrate with glacial acetic acid, and performing solid-liquid separation to obtain crude Poria cocos polysaccharide;

[0030] A5. Mix the crude Poria cocos polysaccharide with DMSO, then add water, collect the resulting precipitate and dry it.

[0031] The second aspect of the present invention provides a pachymaran antibacterial film prepared by the method as described above.

[0032] The third aspect of the present invention provides the use of the above-mentioned Poria polysaccharide nano antibacterial film in food preservation.

[0033] The fourth aspect of the present invention provides the use of the above-mentioned Poria polysaccharide nano antibacterial film in the preparation of medical devices and biomaterials.

[0034] The method for preparing the antibacterial tuckahoe polysaccharide film provided by the present invention uses tuckahoe polysaccharide (straight-chain tuckahoe β-glucan) as a stabilizer and a reducing agent, and utilizes the autonomous film-forming property of the tuckahoe polysaccharide to make the operation of preparing the antibacterial tuckahoe polysaccharide film very simple, without the need to use any other chemical reducing agent and cross-linking agent, and is low in cost and environmentally friendly; the antibacterial tuckahoe polysaccharide film has good antibacterial effect and safety performance against Escherichia coli and Staphylococcus aureus, and can be applied to the fields of food (such as vegetables, fruits, etc.) preservation.

[0035] In addition, in the preparation method provided by the present invention, glycerol can be selectively added to improve the elongation at break of the prepared Poria polysaccharide antibacterial film, thereby broadening its application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The ultraviolet-visible absorption spectra of the nanosilver composite solutions prepared in Examples 1-3 of the present invention and the mixed solutions prepared in Comparative Examples 1-4;

[0037] Figure 2 TEM image and particle size distribution diagram of the nanosilver composite solution prepared in Example 1-2 of the present invention;

[0038] Figure 3 The stress-strain curves of the films prepared in Examples 1-3 and Comparative Examples 1-4 of the present invention;

[0039] Figure 4 The figure is a test result of the torsional tensile load-bearing capacity of the films prepared in Examples 1-2 of the present invention and Comparative Examples 2 and 4;

[0040] Figure 5 The photos of the films prepared in Examples 1-2 of the present invention and Comparative Examples 2 and 4 are shown;

[0041] Figure 6 The scanning electron microscope (SEM) and element mapping results of the Poria cocos polysaccharide antibacterial film prepared in Example 1 of the present invention;

[0042] Figure 7 The thickness measurement results of the films prepared in Examples 1-2 of the present invention and Comparative Examples 2 and 4 are shown;

[0043] Figure 8 The figure is a cytotoxicity test result of the film extracts of the films prepared in Examples 1-2 of the present invention and Comparative Examples 2 and 4;

[0044] Fig. 9 The antibacterial and antibacterial circle diagrams of the films prepared in Examples 1-2 of the present invention and Comparative Examples 2 and 4;

[0045] Fig.10This is a graph showing the fruit preservation test results of Kyoho grapes coated with the antibacterial Poria cocos polysaccharide films prepared in Examples 1-2 of the present invention and Comparative Examples 2 and 4. DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0047] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0048] The present invention provides a method for preparing a polysaccharide antibacterial film, the method comprising the following steps:

[0049] (1) mixing tuckahoe polysaccharide, alkali solution and optionally glycerol to obtain a mixed solution;

[0050] (2) mixing the mixed solution with a silver salt solution to obtain a nanosilver composite solution;

[0051] (3) placing the nanosilver composite solution in a culture dish and drying it at 50-70° C. for 10-16 hours;

[0052] The pachymaran is a straight-chain uniform polysaccharide formed by connecting β-D-furanose residues with β-(1→3)-glycosidic bonds.

[0053] In the method of the present invention, in step (1), the concentration of the alkali solution is 0.08-0.2 mol / L, preferably 0.08-0.15 mol / L, and the tuckahoe polysaccharide of the present invention can be dissolved in the weak alkali solution, and the weak alkaline alkali solution can avoid affecting the film-forming effect. Therefore, by selecting the alkali solution (weak base) of the above concentration, the solubility of tuckahoe polysaccharide in the alkali solution is good, the stability of the prepared nano-silver composite solution is good, and the film-forming effect is not affected.

[0054] In the present invention, the tuckahoe polysaccharide is a water-insoluble straight-chain tuckahoe β-glucan, which has a certain degradation ability and good biological safety. The present invention utilizes the property that the straight-chain tuckahoe β-glucan can reduce silver salts under alkaline conditions, and simultaneously utilizes the characteristics of polyhydroxyl, carbon skeleton and triple helix structure in the straight-chain tuckahoe β-glucan macromolecule to prepare a nano-silver composite solution, in which the nano-silver has a uniform particle size and a small size (average particle size of about 10nm); at the same time, the straight-chain tuckahoe β-glucan has good film-forming properties, therefore, the nano-silver composite solution is poured into a culture dish and dried, and a tuckahoe polysaccharide antibacterial film with good stability, good safety and antibacterial properties can be obtained.

[0055] In a specific embodiment, step (1) comprises: mixing tuckahoe polysaccharide, alkali solution and glycerol to obtain a mixed solution. In order to facilitate the mixing of tuckahoe polysaccharide, alkali solution and glycerol, in a preferred embodiment, step (1) specifically comprises:

[0056] S10, mixing Poria cocos polysaccharide with alkali solution to obtain a polysaccharide solution;

[0057] S20, stirring and mixing the polysaccharide solution and glycerol to obtain a mixed solution.

[0058] In some embodiments, in step S20, the stirring and mixing conditions include: a temperature of 20 to 25° C., a time of 20 to 60 min, and a stirring speed of 100 to 200 rpm.

[0059] In a preferred embodiment, in step (1), the dosage ratio of the pachymaran to the alkali solution is 60 mg: 0.5-2 mL, preferably 0.75-1.5 mL. Within the above dosage range, the pachymaran can be well dissolved in the alkali solution.

[0060] In some embodiments, in step (1), the alkali solution is a sodium hydroxide solution.

[0061] In a preferred embodiment, the weight ratio of glycerol to pachymaran is 0.1-0.5:1, specifically, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1 or 0.5:1. Within the above dosage range, the mechanical properties of the prepared pachymaran antibacterial film are better.

[0062] The present invention does not limit the specific type of the silver salt in step (2), as long as it can provide silver ions, for example, it can be one or more of silver sulfate, silver fluoride and silver nitrate. In a preferred embodiment, in step (2), the silver salt in the silver salt solution is silver nitrate.

[0063] In order to improve the safety and film-forming properties of the prepared Poria polysaccharide antibacterial film, in a preferred embodiment, the dosage ratio of the Poria polysaccharide to the silver salt in the silver salt solution is 960 mg: 0.005-0.06 mmol, more preferably 960 mg: 0.008-0.024 mmol.

[0064] In a preferred embodiment, in step (2), the concentration of the silver salt solution is 10 to 30 mmol / L (mM), specifically, for example, 10 mM, 15 mM, 20 mM, 22 mM, 25 mM, 28 mM or 30 mM.

[0065] In a preferred embodiment, in step (2), the dosage ratio of the tuckahoe polysaccharide to the silver salt solution is 960 mg:0.8 mL, and the concentration of the silver salt solution is 10-30 mM.

[0066] In a preferred embodiment, in step (2), the mixing temperature is 30-40°C, specifically, for example, 30°C, 32°C, 33°C, 34°C, 35°C, 38°C or 40°C.

[0067] In a preferred embodiment, in step (2), the mixing time is 1 to 4 hours, more preferably 1 to 2 hours.

[0068] In a specific embodiment, in step (2), the mixing is carried out by stirring. Furthermore, the stirring speed of the mixing is 100 to 200 rpm.

[0069] In a specific embodiment, in step (3), the drying temperature can be 40°C, 50°C, 55°C, 58°C, 60°C, 65°C or 70°C.

[0070] In a specific embodiment, in step (3), the drying time can be 10 h, 12 h, 13 h, 14 h, 15 h or 16 h.

[0071] The present invention does not specifically limit the amount of the nanosilver composite solution added to the culture dish in step (3), and can be designed accordingly according to the diameter (specification) of the culture dish and the required thickness of the tuckahoe polysaccharide antibacterial film. In a specific embodiment of the present invention, in step (3), the specification of the culture dish is 9 to 15 cm, and the amount of the nanosilver composite solution is 7 to 24 mL. By controlling the amount of the nanosilver composite solution added, a tuckahoe polysaccharide antibacterial film with good consistency and thin thickness can be obtained.

[0072] In some embodiments, step (3) further includes: dialyzing the dried film in water until the pH of the system is 6.5-7.5. The above dialysis step can remove salt from the film, thereby avoiding the restriction of salt on its application and further expanding its application scenarios.

[0073] In the method of the present invention, specifically, the pachymaran is prepared according to the following steps:

[0074] A1. Grinding the Poria cocos and then defatting it to obtain a first residue;

[0075] A2, extracting the first residue with brine and filtering it to obtain a second residue;

[0076] A3, extracting the second residue with alkali solution and filtering to obtain a first filtrate;

[0077] A4, deproteinizing and filtering the first filtrate, mixing the obtained second filtrate with glacial acetic acid, and performing solid-liquid separation to obtain crude Poria cocos polysaccharide;

[0078] A5. Mix the crude Poria cocos polysaccharide with DMSO, then add water, collect the resulting precipitate and dry it to obtain linear Poria cocos β-glucan, i.e., Poria cocos polysaccharide.

[0079] In some embodiments, in step A1, the sieving is through a 60-100 mesh sieve.

[0080] In some embodiments, in step A1, an organic solvent is used for reflux degreasing for 4 to 7 hours. Preferably, the organic solvent is acetone and ethyl acetate.

[0081] In some embodiments, in step A2, the saline is a 0.9% sodium chloride solution.

[0082] In some embodiments, in step A2, the leaching temperature is 80-100° C., and the leaching time is 3-5 hours.

[0083] In some embodiments, in step A3, the alkali solution is a NaOH solution with a concentration of 0.3 to 0.8 mol / L.

[0084] In some embodiments, in step A3, the leaching temperature is 0-10° C., and the leaching time is 1-3 h.

[0085] In some embodiments, in step A4, Sevage method is used for deproteinization, and specifically, the volume ratio of the first filtrate, chloroform and n-butanol is 25:5:1.

[0086] In the present invention, the molecular weight of the tuckahoe polysaccharide obtained by the above extraction process in DMSO is 4.4×105 ~4.6×10 5 g / mol.

[0087] In the preparation method described in the present invention, the selected Poria cocos polysaccharide is insoluble in water and soluble in weak alkali, has antioxidant activity and biosafety, and has good film-forming properties and can spontaneously form a film. In this way, the Poria cocos polysaccharide antibacterial film can be prepared in one step by dissolving the polysaccharide, adding silver salt, and laying the film. There is no need to add chemical reagents such as cross-linking agents and reducing agents. It is green and environmentally friendly and easy to operate.

[0088] The Poria cocos polysaccharide antibacterial film prepared by the method described in the present invention has a wide range of application scenarios, good stability, and good antibacterial effects on Escherichia coli and Staphylococcus aureus; in addition, no other chemical reducing agents and cross-linking agents are required in the preparation process, and the cost is low and environmentally friendly.

[0089] The Poria polysaccharide Tangjing film prepared by the preparation method of the present invention has a wider application scenario and good stability due to the addition of glycerol, and has good mechanical properties and certain loading performance.

[0090] The tuckahoe polysaccharide antibacterial film prepared by the method of the invention has a single main component, namely, polysaccharide and nano silver particles. The tuckahoe polysaccharide antibacterial film has good biocompatibility and soil degradability.

[0091] The tuckahoe polysaccharide antibacterial film prepared by the method of the invention is brown, has certain anti-ultraviolet light performance at 200-400nm, and has good water vapor barrier performance, prevents the loss of water in fruits, and has the ability to keep fruits fresh.

[0092] The present invention also provides a tuckahoe polysaccharide nano antibacterial film prepared by the above method. The silver nanoparticles in the tuckahoe polysaccharide antibacterial film have uniform particle size, small size, good stability and good antibacterial effect.

[0093] The present invention also provides the use of the above-mentioned tuckahoe polysaccharide nano antibacterial film in food preservation, wherein the food can be fruits, vegetables and the like.

[0094] In addition, the present invention also provides the use of the above-mentioned Poria polysaccharide nano antibacterial film in the preparation of medical devices and biomaterials.

[0095] The present invention will be described in detail below by way of examples, but the protection scope of the present invention is not limited thereto. The experimental methods in the following examples, unless otherwise specified, are conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are commercially available products.

[0096] Poria cocos was provided by Hubei Chenmei Chinese Medicine Co., Ltd., production batch number: 2121110220;

[0097] Disposable culture dishes were purchased from White Shark (Lanjieke Technology Co., Ltd.) with a size of 9 cm.

[0098] Preparation Example

[0099] This preparation example is used to illustrate the preparation method of water-insoluble linear Poria β-glucan.

[0100] A1. Grind Poria cocos and pass it through an 80-mesh sieve. Put it into a 150-mesh gauze sample bag and put it into a Soxhlet extractor. Use acetone and ethyl acetate to reflux for 6 hours respectively, collect the defatted residue, and obtain the first residue.

[0101] A2. Take the first residue and add 0.9% sodium chloride solution, heat to 90° C. and stir for 4 hours, collect the filter residue, and repeat the process for several times, and detect by phenol-sulfuric acid method until no sugar content is detected in the filtrate, thereby obtaining the second residue.

[0102] A3. Take the second residue and add 0.5 mol / L NaOH aqueous solution, stir at 5°C for 2 h, collect the filtrate, and repeat twice, collect all the filtrates to obtain the first filtrate.

[0103] A4. Take the first filtrate, deproteinize by Sevage method according to the ratio of first filtrate: chloroform: n-butanol = 25:5:1, stir for 30 minutes, repeat filtration 3 times, collect all supernatants to obtain a second filtrate, add 99% glacial acetic acid to the second filtrate to adjust the pH to neutral and stir continuously until a large amount of precipitate is produced, collect the precipitate, add 95% ethanol to the precipitate at a mass volume ratio of 1:1, mix well and let stand for 6 hours, collect the precipitate, take the precipitate after alcohol washing, add distilled water at a mass volume ratio of 1:10, stir well and collect the precipitate, repeat 3 times and collect the precipitate obtained, which is crude Poria cocos polysaccharide.

[0104] A5. Dissolve the above crude Poria cocos polysaccharide in DMSO to obtain a 1 mg / mL crude Poria cocos polysaccharide DMSO solution, add ultrapure water dropwise using a constant pressure dropping funnel while stirring continuously, collect the resulting precipitate and freeze-dry it to obtain linear Poria cocos β-glucan (PCPA), i.e., Poria cocos polysaccharide.

[0105] The results of analysis showed that the tuckahoe polysaccharide is a straight-chain homogeneous polysaccharide composed of β-D-furanose glucose residues connected by β-(1→3)-glycosidic bonds.

[0106] Example 1

[0107] This example is used to illustrate the pachymaran and its preparation method described in the present invention.

[0108] (1) 960 mg of the Poria cocos polysaccharide prepared in the above preparation example was dissolved in 16 mL of a 0.1 mol / L NaOH solution to obtain a polysaccharide solution with a concentration of 60 mg / mL; 288 mg of glycerol (i.e., the weight ratio of glycerol to Poria cocos polysaccharide was 30%) was added to the polysaccharide solution, and the mixture was stirred (temperature was 25° C., time was 0.5 h, stirring speed was 100 rpm), to obtain a mixed solution;

[0109] (2) adding 0.8 mL of a 30 mM silver nitrate solution to the mixed solution obtained in step (1), stirring and mixing (temperature: 35° C., time: 1.5 h, stirring speed: 100 rpm) to obtain a pachymannan / nanosilver solution (PG30-Ag30), i.e., a nanosilver composite solution;

[0110] (3) Take 8 mL of the nanosilver composite solution obtained in step (2), pour it into a disposable culture dish with a diameter (specification) of 9 cm, and dry it in a drying oven at 60° C. for 12 h to obtain a Poria cocos polysaccharide antibacterial film (PGF30-Ag30).

[0111] Example 2

[0112] The method described in Example 1 is followed, except that in step (2), the concentration of the silver nitrate solution is 10 mM.

[0113] Example 3

[0114] The method described in Example 2 was followed, except that in step (1), no glycerol was added.

[0115] Example 4

[0116] The method described in Example 1 was followed, except that in step (1), the mass of glycerol was 96 mg.

[0117] Example 5

[0118] The method described in Example 1 was followed, except that in step (2), the mass of glycerol was 480 mg.

[0119] Comparative Example 1

[0120] The method described in Example 5 is followed, except that in step (3), no silver nitrate solution is added.

[0121] Specifically, the following steps are included:

[0122] (1) 960 mg of the Poria cocos polysaccharide prepared in the above preparation example was dissolved in 16 mL of a 0.1 mol / L NaOH solution to obtain a polysaccharide solution with a concentration of 60 mg / mL; 480 mg of glycerol was added to the polysaccharide solution, and the mixture was stirred (temperature 25° C., time 0.5 h, stirring speed 100 rpm) to obtain a mixed solution;

[0123] (2) Take 8 mL of the mixed solution (PG50) prepared in step (1), pour it into a disposable culture dish with a diameter (specification) of 9 cm, and dry it in a drying oven at 60° C. for 12 h to obtain a pachymannan-glycerol film (PGF50).

[0124] Comparative Example 2

[0125] The method described in Comparative Example 1 was followed, except that the mass of glycerol was 288 mg.

[0126] Comparative Example 3

[0127] The method described in Comparative Example 1 was followed, except that the mass of glycerol was 96 mg.

[0128] Comparative Example 4

[0129] The method described in Comparative Example 1 was followed, except that no glycerol was added.

[0130] In the accompanying drawings obtained from the following test examples, "Pokriasis polysaccharide + 30 glycerol + 30 silver" represents the product prepared in Example 1 (nanosilver composite solution or Poriasis polysaccharide antibacterial film), "Pokriasis polysaccharide + 30 glycerol + 10 silver" represents the product prepared in Example 2; "Pokriasis polysaccharide + 10 silver" represents the product prepared in Example 3; "Pokriasis polysaccharide + 50 glycerol" represents the product prepared in Comparative Example 1; "Pokriasis polysaccharide + 30 glycerol" represents the product prepared in Comparative Example 2; "Pokriasis polysaccharide + 10 glycerol" represents the product prepared in Comparative Example 3; "Pokriasis polysaccharide" represents the product prepared in Comparative Example 4.

[0131] Test Example 1

[0132] (1) UV-Vis spectrophotometer

[0133] The nanosilver composite solutions prepared in Examples 1-3 and the mixed solutions prepared in Comparative Examples 1-4 were tested using a UV-visible spectrophotometer to measure the UV absorption peak positions and absorbances of the nanosilver solutions at different time points. The test results are shown in FIG. Figure 1 shown.

[0134] Depend on Figure 1It can be seen from the UV-visible absorption spectrum that the nanosilver composite solution has a peak at 400nm, while the mixed solution without nanosilver has no peak, indicating that the nanosilver composite solution containing nanosilver was successfully prepared in Examples 1-3.

[0135] (2) Transmission electron microscopy

[0136] A small amount of the nanosilver composite solution prepared in Example 1-2 was placed on a copper mesh, and the solution was air-dried before testing to observe the morphology of the nanosilver. ImageJ was used to calculate the particle size distribution. The test results are as follows: Figure 2 shown.

[0137] Depend on Figure 2 It can be seen from the transmission electron microscopy image that Poria cocos polysaccharide / nanosilver is spherical and has no aggregation phenomenon. Figure 2 It can be seen from the particle size distribution diagram that the particle size of the linear Poria β-glucan / nanosilver prepared in Example 1 is 8-20 nm, and the average particle size is 12.3 nm; the particle size of the linear Poria β-glucan / nanosilver prepared in Example 2 is 5-20 nm, and the average particle size is 9.0 nm.

[0138] Test Example 2

[0139] The films prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to mechanical property measurement. The prepared films were cut into a size of 40 mm*5 mm in length and width, and both ends of the films were clamped on the two ends of a universal stretching instrument. The films were pulled at a constant speed of 60 mm / min. The stress-strain curves obtained by detecting the films according to the above method were as follows: Figure 3 As shown, the tensile strength (TS), elongation at break (EAB) and Young's modulus as well as the torsional tensile load-bearing capacity of the film are Figure 4 And as shown in Table 1.

[0140] Table 1

[0141] serial number Tensile strength(MPa) Elongation at break (%) Young's modulus (MPa) Example 1 5.94±0.50 128.77±12.46 15.75±1.91 Example 2 6.24±0.65 145.07±11.49 16.24±2.09 Example 3 25.92±5.00 35.29±4.86 682.46±72.63 Comparative Example 1 3.41±0.49 173.43±7.72 3.94±0.98 Comparative Example 2 7.78±0.86 177.06±9.17 11.51±2.01 Comparative Example 3 16.13±3.36 102.68±5.44 369.74±51.57 Comparative Example 4 21.89±5.93 21.93±3.56 773.70±77.35

[0142] It can be seen from Table 1 that the films prepared in Examples 1-3 of the present invention and Comparative Examples 1-4 all have good mechanical properties.

[0143] By comparing Example 1 with Comparative Example 2, it can be seen that the addition of nanosilver particles has little effect on the mechanical properties of the film.

[0144] Compared with Examples 1-2, Example 3 does not add glycerol; compared with Comparative Examples 1-3, Comparative Example 4 does not add glycerol; it can be seen from the above examples and comparative examples that by adding glycerol, the elongation at break of the film is significantly improved, but the tensile strength and Young's modulus are reduced.

[0145] From the above content, it can be seen that by adding glycerol and controlling the amount of glycerol added, Poria cocos polysaccharide antibacterial films with different mechanical properties can be obtained, thereby broadening the application scenarios of Poria cocos polysaccharide antibacterial films.

[0146] Test Example 3

[0147] (1) The film pictures obtained in Examples 1-2 and Comparative Examples 2 and 4 are as follows: Figure 5 shown.

[0148] Depend on Figure 5 It can be seen that the antibacterial film of Poria cocos polysaccharide prepared in Example 1-2 of the present invention is brown.

[0149] (2) The antibacterial tuckahoe polysaccharide film prepared in Example 1 was characterized using a scanning electron microscope (SEM). Figure 6 shown.

[0150] Depend on Figure 6 It can be seen that the surface of the film prepared in Example 1 of the present invention is uniform, the silver nanoparticles are evenly distributed on the surface of the film, and the cross section shows that the film is relatively dense.

[0151] (3) The thickness of the films prepared in Examples 1-2 and Comparative Examples 2 and 4 was measured. The measurement method was as follows: the thickness of the films was measured using a digital micrometer (Chuanlu Measurement Co., Ltd., Shanghai, China). Three films were selected from each group, and the film thickness was measured at four points on each film. The average value was taken. The test results are shown in Table 1. Figure 7 shown.

[0152] Depend on Figure 7 It can be seen that the film thickness of Comparative Example 2 and Example 1-2 is about 60-70 um, and the film thickness of Comparative Example 4 is about 40 um.

[0153] Test Example 4

[0154] (1) Biocompatibility

[0155] The films obtained in Examples 1-2 and Comparative Examples 2 and 4 were dialyzed in distilled water until the pH of the system was 7. The dialyzed films were extracted with corresponding cell culture medium at 37° C. for 24 h, and the obtained film extracts were co-cultured with L929 cells. The test results are as follows: Figure 8 shown.

[0156] Depend on Figure 8 It can be seen that the antibacterial pachymaran film prepared in Examples 1-2 of the present invention has no significant effect on the survival rate of L929 cells, indicating that the antibacterial pachymaran film prepared by the method provided by the present invention has good biocompatibility.

[0157] (2) Antibacterial properties

[0158] The films obtained in Examples 1-2 and Comparative Examples 2 and 4 were dialyzed in distilled water until the pH of the system was 7. The dialyzed films were cut and then co-cultured with Escherichia coli and Staphylococcus aureus. The test results are as follows: Figure 8 shown.

[0159] Depend on Fig. 9 It can be seen that the antibacterial film of Poria cocos polysaccharide prepared in Examples 1-2 of the present invention has good antibacterial properties.

[0160] (3) Degradation performance

[0161] The film prepared in Example 1-2 was cut and then buried in soil to observe its degradation.

[0162] The results showed that about 15 days after the film was buried in the soil, obvious shrinkage began to be observed; then, as time went on, it gradually disintegrated, indicating that the antibacterial Poria polysaccharide film prepared by the present invention has good soil degradability.

[0163] Test Example 5

[0164] The films prepared in Examples 1-2 and Comparative Examples 2 and 4 were used to preserve Kyoho grapes. The specific steps were as follows: (1) Wipe off dirt on the surface of fresh Kyoho grapes, divide the grapes into five groups and place them in plastic jars; (2) Cover the openings of the plastic jars with the prepared films, seal the jars tightly with rubber bands, and store them under strong light for 12 days. Among them, the Poria cocos polysaccharide + 30 glycerol + 30 silver film group: covered with the film prepared in Example 1; the Poria cocos polysaccharide + 30 glycerol + 10 silver film group: covered with the film prepared in Example 2; the Poria cocos polysaccharide + 30 glycerol film group: covered with the film prepared in Comparative Example 2; the Poria cocos polysaccharide film group: covered with the film prepared in Comparative Example 4; and the blank control group: not covered with any film. The test results are as follows: Fig.10 shown.

[0165] Depend on Fig.10 It can be seen that after 12 days of storage, the grapes in the blank control group without the film coating showed obvious water loss, the fruit skin shrank, and the fruit surface had mildew and other corruption conditions. The fruit water loss in the Poria polysaccharide film group and the Poria polysaccharide + 30 glycerol film group was reduced, while the Poria polysaccharide + 30 glycerol + 30 silver film group and the Poria polysaccharide + 30 glycerol + 10 silver film group did not show signs of corruption such as mildew, and the fruit skin did not shrink, and the fruit state was good. The above results show that the Poria polysaccharide antibacterial film prepared by the method provided by the present invention has a good preservation effect on fruits and can be used for fruit preservation.

[0166] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a pachymaran antibacterial film, characterized in that: The method comprises the following steps: (1) mixing tuckahoe polysaccharide, alkali solution and optionally glycerol to obtain a mixed solution; (2) mixing the mixed solution with a silver salt solution to obtain a nanosilver composite solution; (3) placing the nanosilver composite solution in a culture dish and drying it at 50-70° C. for 10-16 hours; Wherein, the tuckahoe polysaccharide is a straight-chain uniform polysaccharide formed by β-D-furanose glucose residues connected by β-(1→3)-glycosidic bonds; The concentration of the alkali solution is 0.08-0.2 mol / L.

2. The method according to claim 1, characterized in that: Step (1) specifically includes: S10, mixing Poria cocos polysaccharide with alkali solution to obtain a polysaccharide solution; S20, stirring and mixing the polysaccharide solution and glycerol to obtain a mixed solution; Preferably, in step S20, the stirring and mixing conditions include: a temperature of 20 to 25° C., a time of 20 to 60 min, and a stirring speed of 100 to 200 rpm.

3. The method according to claim 1 or 2, characterized in that: The dosage ratio of the tuckahoe polysaccharide to the alkali solution is 60 mg: 0.5-2 mL; and / or The weight ratio of the glycerol to the pachymaran is 0.1-0.5:1; and / or The alkali solution is sodium hydroxide solution.

4. The method according to any one of claims 1 to 3, characterized in that: In step (2), in the silver salt solution, the silver salt is silver nitrate; and / or In step (2), the mixing operating conditions include: temperature of 30-40° C., time of 1-4 h, and stirring speed of 100-200 rpm.

5. The method according to any one of claims 1 to 4, characterized in that: The dosage ratio of the tuckahoe polysaccharide to the silver salt in the silver salt solution is 960 mg: 0.005-0.06 mmol; and / or The concentration of the silver salt solution is 10-30 mmol / L.

6. The method according to claim 1, characterized in that In step (3), the size of the culture dish is 9 to 15 cm, and the amount of the nanosilver composite solution is 7 to 24 mL; and / or Step (3) also includes: dialyzing the dried film in water until the pH of the system is 6.5 to 7.

5.

7. The method according to any one of claims 1 to 6, characterized in that: The method also includes preparing pachymaran according to the following steps: A1. Grinding and sieving the Poria cocos, and then defatting the Poria cocos to obtain a first residue; A2, extracting the first residue with brine and filtering it to obtain a second residue; A3, extracting the second residue with alkali solution and filtering to obtain a first filtrate; A4, deproteinizing and filtering the first filtrate, mixing the obtained second filtrate with glacial acetic acid, and performing solid-liquid separation to obtain crude Poria cocos polysaccharide; A5. Mix the crude Poria cocos polysaccharide with DMSO, then add water, collect the resulting precipitate and dry it.

8. The antibacterial film of Pachymaran prepared by the method according to any one of claims 1 to 7.

9. Use of the Poria cocos polysaccharide nano antibacterial film according to claim 8 in food preservation.

10. Use of the Poria cocos polysaccharide nano antibacterial film according to claim 8 in the preparation of medical devices and biomaterials.

Images