Microencapsulated nano-silver composite material with long-acting antibacterial function and preparation method thereof

Abstract

The present application relates to the technical field of antibacterial material, in particular to a microencapsulated nanometer silver composite material with long-acting antibacterial function and a preparation method thereof.The preparation method of the microencapsulated nanometer silver composite material with long-acting antibacterial function comprises the following steps: fermenting culture medium by using a composite microorganism composed of Bacillus thuringiensis and Leucothrix sp., obtaining a fermentation liquor, and then carrying out microwave reaction on the fermentation liquor and a silver nitrate solution containing an emulsifier and a dispersing agent to obtain a nanometer silver solution, and then reacting the nanometer silver solution with a quaternary ammonium chitosan solution to obtain the microencapsulated nanometer silver composite material.The nanometer silver obtained by using the preparation method has a particle size of only 5.7-9.1nm, and the stability of the nanometer silver can be improved through microencapsulation, so that the silver ions are released slowly, the antibacterial time is prolonged, and a high-efficiency antibacterial effect is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanobiomaterials, and in particular to a microencapsulated nanosilver composite material with long-acting antibacterial function and a preparation method thereof. BACKGROUND

[0002] In many fields such as medicine, textiles, food packaging, microbial contamination has always been a key problem that needs to be solved. Nanosilver has attracted much attention in antibacterial applications due to its unique physical and chemical properties. Its antibacterial mechanism is mainly based on the release of silver ions, which can interact with biological macromolecules such as proteins and nucleic acids in microorganisms, thereby effectively inhibiting or killing various bacteria, fungi, viruses and other microorganisms.

[0003] However, although nanosilver has excellent antibacterial performance, it still faces a significant bottleneck in practical application: short antibacterial time. In actual use scenarios, such as wound dressings in the medical field, antibacterial coatings for medical devices, antibacterial films in the food packaging industry, and antibacterial fibers in the textile field, long-term and effective antibacterial effect is often required. However, after the initial rapid release of silver ions, the silver ion concentration decreases rapidly over time, and the antibacterial activity also decreases significantly, making it difficult to meet the demand for long-acting antibacterial effect, which greatly limits the widespread application of nanosilver in more scenarios with high requirements for long-acting antibacterial effect.

[0004] Therefore, it is of great practical significance and broad application prospect to develop a new type of nanosilver antibacterial material and related preparation process. SUMMARY

[0005] To solve the above technical problems, the present application provides a microencapsulated nanosilver composite material with long-acting antibacterial function and a preparation method thereof. The microencapsulated nanosilver composite material prepared by the preparation method of the present application can achieve slow release of silver ions and achieve long-acting antibacterial effect.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a microencapsulated nanosilver composite material with long-acting antibacterial function, comprising:

[0008] (1) fermenting a composite microorganism in a culture medium to obtain a fermentation liquor, and reacting the fermentation liquor with a silver nitrate solution, an emulsifier and a dispersant under microwave conditions to obtain a nanosilver solution; the composite microorganism is composed of Bacillus thuringiensis and Leucothrix mucor in a weight ratio of 2-5:1-3;

[0009] (2) mixing the nano-silver solution obtained in step (1) with a quaternary ammonium chitosan solution, and spray drying to obtain a microencapsulated nano-silver composite material.

[0010] Preferably, the culture medium in step (1) is obtained by homogenizing oat, kiwi, lycium barbarum, glucose and water in a weight ratio of (30-40):(20-30):(8-12):(10-30):(200-300); the fermentation temperature is 28-35℃, the pH value is 7.0-8.0, and the time is 24-48h.

[0011] Preferably, the concentration of the silver nitrate solution in step (1) is 0.3-0.6mol / L.

[0012] Preferably, the emulsifier in step (1) is one or both of polyvinylpyrrolidone K30 and sodium dodecyl sulfate, and the dispersing agent is one or more of gum arabic, gelatin and sodium alginate.

[0013] Preferably, the microwave power of the reaction in step (1) is 100-300W, the temperature is 40-60℃, and the time is 20-40min.

[0014] Preferably, the mass concentration of the quaternary ammonium chitosan solution in step (2) is 0.1%-5%, and the volume ratio of the nano-silver solution to the quaternary ammonium chitosan solution is 1:2-4.

[0015] Preferably, the temperature of the reaction in step (2) is 35-55℃, the pH value is 4-6, the stirring speed is 300-800r / min, and the time is 30-60min.

[0016] Preferably, the temperature of the spray drying in step (2) is 70-85℃.

[0017] The application also provides a microencapsulated nano-silver composite material prepared by the above preparation method.

[0018] The application also provides application of the above microencapsulated nano-silver composite material in preparation of long-acting antibacterial products.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] The application provides a preparation method of microencapsulated nanosilver composite material, comprising: fermenting culture medium by composite microorganisms composed of Bacillus thuringiensis and Agarivorans albus to obtain fermentation liquor, and then carrying out microwave reaction on the fermentation liquor and silver nitrate solution containing emulsifier and dispersant to obtain nanosilver solution, and then carrying out reaction on the nanosilver solution and quaternary ammonium chitosan solution to obtain the microencapsulated nanosilver composite material. The nanosilver particle size obtained by the preparation method is only 5.7-9.1 nm, and the stability of the nanosilver can be improved by microencapsulation, the silver ion is slowly released, the antibacterial time is prolonged, and the high-efficiency antibacterial effect is achieved. DETAILED DESCRIPTION

[0021] The application provides a preparation method of microencapsulated nanosilver composite material with long-acting antibacterial function, comprising:

[0022] (1) fermenting culture medium by composite microorganisms composed of Bacillus thuringiensis and Agarivorans albus according to a weight ratio of 2-5:1-3 to obtain fermentation liquor, and then carrying out microwave reaction on the fermentation liquor, silver nitrate solution, emulsifier and dispersant to obtain nanosilver solution;

[0023] (2) carrying out mixed reaction on the nanosilver solution obtained in step (1) and quaternary ammonium chitosan solution, and then carrying out spray drying to obtain the microencapsulated nanosilver composite material.

[0024] The culture medium in step (1) is preferably obtained by homogenizing oats, kiwi fruit, lonicera japonica fruit, glucose and water according to a weight ratio of (30-40):(20-30):(8-12):(10-30):(200-300), and the weight ratio is more preferably 35:25:10:20:250. The oats contain rich carbohydrates which can be decomposed into glucose by microorganisms to provide energy for the growth of the microorganisms, and also contain rich minerals, vitamins and various functional components; the kiwi fruit is rich in various vitamins such as vitamin C and vitamin E, and the vitamin C has antioxidant effect and can protect some components sensitive to oxidation in the culture medium; the lonicera japonica fruit can provide various bioactive components, and triterpenoids such as oleanolic acid and ursolic acid can produce components with stronger antioxidant property after being utilized by microorganisms, and can protect the nanosilver from oxidation in the subsequent reaction; and the glucose can be directly absorbed and utilized by the microorganisms to promote the rapid increase of the number of the microorganisms. The culture medium can provide comprehensive nutritional components for the composite microorganisms and promote the composite microorganisms to produce more antioxidant metabolites to protect the nanosilver.

[0025] The Bacillus thuringiensis in the application is Bacillus thuringiensis CI CC21298, and the Agarivorans albus is Agarivorans albus CCIC 21298. ​The bacillus thuringiensis has a bacterial activity of preferably 5-10 billion CFU / g, more preferably 8 billion CFU / g, and the white algal bacterium has a bacterial activity of preferably 2-5 billion CFU / g, more preferably 3 billion CFU / g. The addition amount of the complex microorganism is 0.5-2% of the total weight of the oat, kiwi fruit, privet fruit and glucose; the fermentation temperature is preferably 28-35 DEG C, more preferably 30 DEG C, the pH value is preferably 7.0-8.0, more preferably 7.5, and the time is preferably 24-48h, more preferably 36h.

[0026] In the complex microorganism fermentation process of the application, the new antioxidant components produced by the microorganism and the original antioxidant components in the raw materials produce a synergistic effect, which significantly enhances the overall antioxidant capacity of the fermentation liquor, and in the subsequent reaction, silver ions can be reduced to obtain nano-silver with smaller particle size, and in the encapsulation reaction, the nano-silver is protected from oxidation, thereby improving the synthesis efficiency of the encapsulated nano-silver composite material.

[0027] The concentration of the silver nitrate solution in step (1) is preferably 0.3-0.6 mol / L, more preferably 0.48 mol / L.

[0028] The emulsifier in step (1) is preferably one or both of polyvinylpyrrolidone K30 and sodium dodecyl sulfate, and the dispersant is preferably one or more of gum arabic, gelatin and sodium alginate. The combination of the emulsifier and the dispersant can control the formation of spherical nano-silver with uniform particle size and good dispersibility, prevent the agglomeration of nano-silver, and improve the stability.

[0029] The microwave power of the reaction in step (1) is preferably 100-300W, more preferably 200W, the temperature is preferably 40-60 DEG C, more preferably 50 DEG C, and the time is preferably 20-40min, more preferably 30min. The use of microwave in the preparation of nano-silver can make the molecules in the reaction system move quickly, accelerate the reaction rate, improve the dispersibility of nano-silver, make the nano-silver particles more uniformly dispersed in the solution, and promote the rapid nucleation of silver ions, thereby forming a large number of crystal nuclei in a short time, and then obtaining spherical nano-silver particles with small and uniform particle size.

[0030] The method of step (1) is used to make the nano-silver in the system uniformly dispersed and small in particle size, thereby improving the bactericidal capacity of the nano-silver.

[0031] The mass concentration of the quaternary ammonium chitosan solution in step (2) is preferably 0.1%-5%, more preferably 3%, and the volume ratio of the nano-silver solution to the quaternary ammonium chitosan solution is preferably 1:2-4, more preferably 1:3.

[0032] The temperature of the reaction in step (2) is preferably 35-55 DEG C, more preferably 40 DEG C, the pH value is preferably 4-6, more preferably 5, the stirring speed is preferably 300-800 r / min, more preferably 500 r / min, and the time is preferably 30-60 min, more preferably 45 min; and the temperature of the spray drying is preferably 70-85 DEG C, more preferably 80 DEG C.

[0033] The quaternary ammonium chitosan in the application is quaternary ammonium chitosan 100K, which has good water solubility compared with chitosan, is more easily mixed with other substances, is more conducive to forming a stable microcapsule system, has better flexibility and mechanical strength, and has obvious enhancement of antibacterial property.

[0034] The application embeds the quaternary ammonium chitosan with antibacterial property into nano-silver through encapsulation, so that the nano-silver can be slowly released, the antibacterial property is improved, the slow release of silver ions is realized, and long-acting antibacterial effect is achieved.

[0035] The application also provides a microencapsulated nano-silver composite material prepared by the preparation method.

[0036] The application also provides application of the microencapsulated nano-silver composite material in preparation of long-acting antibacterial products.

[0037] The microencapsulated nano-silver composite material can be used in antibacterial coating of fabrics, food packaging materials, bathroom facilities, filter screen of air purification equipment, wound dressings, medical instrument disinfection, oral materials (dental cotton tips, root canal filling materials, etc.), and the like.

[0038] In the application, all the raw material components are commercially available products well known to those skilled in the art, unless otherwise specified.

[0039] The technical solutions in the application will be clearly and completely described below in combination with the embodiments in the application. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0040] In the following embodiments, all the methods are conventional methods, unless otherwise specified.

[0041] In the following embodiments, all the materials and reagents, unless otherwise specified, can be obtained through commercial channels.

[0042] Example 1

[0043] Preparation of nano-silver

[0044] (1) Preparation of fermentation broth

[0045] Mix 35 parts by weight of oat, 25 parts by weight of kiwi fruit, 10 parts by weight of lycium fruit and 20 parts by weight of glucose uniformly, place in a cell disrupter, add 250 parts by weight of water, disrupt at 30000 r / min for 5 min, keep at 72℃ for 15 s, cool, and obtain a culture medium;

[0046] Add 1% of the total weight of the complex microorganism of oat, kiwi fruit, lycium fruit and glucose, ferment at 30℃ and pH 7.5 for 36 h;

[0047] The complex microorganism is composed of Bacillus thuringiensis CICC 21298 and Agarivorans albus CICC 10798 in a weight ratio of 4:2. The bacterial activity of Bacillus thuringiensis CICC 21298 is 8 billion CFU / g, and the bacterial activity of Agarivorans albus CICC 10798 is 3 billion CFU / g.

[0048] (2) Preparation of nano-silver

[0049] Mix the silver nitrate solution, the polyvinylpyrrolidone K30 solution and the sodium alginate solution, and then mix with the fermentation broth, and react under the condition of 200W and 50℃ microwave for 30 min to obtain a nano-silver solution.

[0050] The concentration of the silver nitrate solution is 0.48 mol / L; the concentration of the polyvinylpyrrolidone K30 solution is 2 mol / L; the concentration of the sodium alginate solution is 54 g / L; the volume ratio of the silver nitrate solution, the polyvinylpyrrolidone K30 solution and the sodium alginate solution is 1:1:1; and the ratio of the total volume of the silver nitrate solution, the polyvinylpyrrolidone K30 solution and the sodium alginate solution to the volume of the fermentation broth is 1:2.

[0051] Example 2

[0052] Preparation of nano-silver

[0053] (1) Preparation of fermentation broth

[0054] Mix 30 parts by weight of oat, 20 parts by weight of kiwi fruit, 8 parts by weight of lycium fruit and 10 parts by weight of glucose uniformly, place in a cell disrupter, add 200 parts by weight of water, disrupt at 33000 r / min for 3 min, keep at 70℃ for 18 s, cool, and obtain a culture medium;

[0055] Add 0.5% of the total weight of the complex microorganism of oat, kiwi fruit, lycium fruit and glucose, ferment at 28℃ and pH 7.0 for 48 h.​​​

[0056] The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3.

[0057] (2) Preparation of nano-silver

[0058] The silver nitrate solution, the sodium dodecyl sulfate solution and the gum arabic solution are mixed, and then mixed with the fermentation liquor, and then reacted under the condition of 100W and 40℃ microwave for 40min to obtain a nano-silver solution.

[0059] The concentration of the silver nitrate solution is 0.3mol / L; the concentration of the sodium dodecyl sulfate solution is 0.3mol / L; the concentration of the gum arabic solution is 3%(w / v); the volume ratio of the silver nitrate solution, the sodium dodecyl sulfate solution and the gum arabic solution is 1:2:2; the ratio of the total volume of the silver nitrate solution, the sodium dodecyl sulfate solution and the gum arabic solution to the volume of the fermentation liquor is 1:1.

[0060] Example 3

[0061] Preparation of nano-silver

[0062] (1) Preparation of fermentation liquor

[0063] 40 parts by weight of oat, 30 parts by weight of kiwi fruit, 12 parts by weight of privet fruit and 30 parts by weight of glucose are uniformly mixed, and then placed in a cell disrupter, 300 parts by weight of water is added, and then the mixture is disrupted at 28000r / min for 8min, and then kept at 72℃ for 13s, and then cooled to obtain a culture medium.

[0064] 2% of the complex microorganism in total weight of oat, kiwi fruit, privet fruit and glucose is added, and then the mixture is fermented at 35℃ and pH value of 8.0 for 24h.

[0065] The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The complex microorganism is composed of Bacillus thuringiensis CICC 10798 and Agarivorans albus CICC 21298 in a weight ratio of 2:3. The bacterial activity of CICC 10798 is 2 billion CFU / g;

[0066] (2) Preparation of nano-silver

[0067] After mixing the silver nitrate solution, the polyvinylpyrrolidone K30 solution and the gelatin solution, the mixture is mixed with the fermentation broth of step (1) and reacted under the condition of 100 W and 40℃ microwave for 40 min to obtain a nano-silver solution.

[0068] The concentration of the silver nitrate solution is 0.6 mol / L; the concentration of the polyvinylpyrrolidone K30 solution is 3 mol / L; the concentration of the gelatin solution is 3% (w / v); the volume ratio of the silver nitrate solution, the polyvinylpyrrolidone K30 solution and the gelatin solution is 1:3:3; and the ratio of the total volume of the silver nitrate solution, the polyvinylpyrrolidone K30 solution and the gelatin solution to the volume of the fermentation broth is 1:3.

[0069] Comparative Example 1

[0070] The specific implementation is the same as that of Example 1, except that the composite microorganism is composed of Lactiplantibacillus plantarum 23489 and Saccharomyces cerevisiae 1263 according to a weight ratio of 4:2, Lactiplantibacillus plantarum 23489 has a bacterial activity of 80 billion CFU / g, and Saccharomyces cerevisiae 1263 has a bacterial activity of preferably 30 billion CFU / g.

[0071] Comparative Example 2

[0072] The specific implementation is the same as that of Example 1, except that the culture medium is replaced by a basic composite culture medium (the ingredients include glucose 20 g / L, bran 8 g / L, yeast extract 10 g / L, peptone 10 g / L, magnesium sulfate 3 g / L, dipotassium hydrogen phosphate 3 g / L, calcium carbonate 8 g / L, and the initial pH is 6.8-7).

[0073] Comparative Example 3

[0074] A mixed solution was obtained by mixing equal volumes of 0.48 mol / L silver nitrate solution, 4 mol / L polyvinylpyrrolidone K30 solution and 54 g / L sodium alginate solution; a 0.08 mol / L tannic acid solution and a 0.02 mol / L sodium citrate solution were mixed at 60°C and then quickly transferred into the mixed solution (the total volume of the tannic acid solution and the sodium citrate solution was 4 times the volume of the mixed solution) and stirred for 10 min at constant temperature, and then boiled for 20 min in an oil bath to obtain a nano-silver solution.

[0075] Test Example 1

[0076] Nano-silver particle size

[0077] The nano-silver solutions of Examples 1-3 and Comparative Examples 1-3 were filtered, and the separated nano-silver was washed by centrifugation 4 times with ethanol and distilled water, and then spray-dried at 80°C to a water content of 5% to obtain a powder without obvious particles.

[0078] 2 mg of the dried nano-silver of Examples 1-3 and Comparative Examples 1-3 was added to 1.0 mL of purified water and dispersed uniformly, and then measured by a laser particle size analyzer. The specific results are shown in Table 1.

[0079] Table 1 Nano-silver particle size of Examples 1-3 and Comparative Examples 1-3

[0080] Group Particle diameter (nm) Example 1 5.7 Example 2 7.2 Example 3 9.1 Comparative Example 1 15.2 Comparative Example 2 13.8 Comparative Example 3 35.2

[0081] The nano-silver of Examples 1-3 and Comparative Examples 1-3 was well dispersed and spherical with uniform particle size distribution. As shown by the data of Example 1 and Comparative Example 1-2, the particle size of the nano-silver can be reduced by using the composite microorganism and culture medium of the present application. As shown by the comparison of the particle sizes of Example 1 and Comparative Example 3, the nano-silver prepared by the method of the present application has a smaller particle size, which makes the antibacterial effect better.

[0082] Example 4

[0083] Preparation of microencapsulated nano-silver composite material

[0084] The nano-silver solution obtained in Example 1 was mixed with a 3% mass concentration of quaternized chitosan K100 solution at a volume ratio of 1:3, and reacted at 40°C, pH 5.0 and 500 r / min for 45 min, and then spray-dried at 80°C to a water content of 5% to obtain a microencapsulated nano-silver composite material.

[0085] Example 5

[0086] Preparation of microencapsulated nano-silver composite material

[0087] The nanosilver solution obtained in Example 2 was mixed with a 0.1% by mass quaternized chitosan K100 solution at a volume ratio of 1:4, and reacted at 55°C, pH 6.0, and 800 r / min for 30 min. The reaction product was spray-dried at 70°C until the water content was 8% to obtain a microencapsulated nanosilver composite.

[0088] Example 6

[0089] Preparation of a microencapsulated nanosilver composite

[0090] The nanosilver solution obtained in Example 3 was mixed with a 5% by mass quaternized chitosan K100 solution at a volume ratio of 1:2, and reacted at 35°C, pH 4.0, and 300 r / min for 60 min. The reaction product was spray-dried at 85°C until the water content was 4% to obtain a microencapsulated nanosilver composite.

[0091] Comparative Example 4

[0092] The specific embodiment was the same as in Example 4, except that the nanosilver solution was replaced with the nanosilver solution of Comparative Example 1.

[0093] Comparative Example 5

[0094] The specific embodiment was the same as in Example 4, except that the nanosilver solution was replaced with the nanosilver solution of Comparative Example 2.

[0095] Comparative Example 6

[0096] The specific embodiment was the same as in Example 4, except that the nanosilver solution was replaced with the nanosilver solution of Comparative Example 3.

[0097] Comparative Example 7

[0098] The specific embodiment was the same as in Example 4, except that the quaternized chitosan K100 was replaced with chitosan.

[0099] Test Example 2

[0100] Antibacterial properties of a microencapsulated nanosilver composite

[0101] The antibacterial properties of the nanosilver (spray-dried to a water content of 5%) of Example 1 and Comparative Examples 1-3, and the composites of Examples 4-6 and Comparative Examples 4-7 were measured using Escherichia coli (E. coli 0999) and Staphylococcus aureus (S. aureus 21600). The antibacterial properties of the nanosilver (spray-dried to a water content of 5%) of Example 1 and Comparative Examples 1-3, and the composites of Examples 4-6 and Comparative Examples 4-7 were measured using Escherichia coli (E. coli 0999) and Staphylococcus aureus (S. aureus 21600).

[0102] ​E. coli and S. aureus were inoculated on nutrient agar, activated at 37℃ for 24h, and suitable single colonies were screened and inoculated in nutrient broth, cultured at 37℃ in a constant temperature shaker until the concentration of the bacterial solution reached 10 6 CFU / mL.

[0103] The nanosilver of Example 1 and Comparative Examples 1-3 and the composite material of Example 4-6 and Comparative Examples 4-7 were respectively ultrasonically treated at room temperature for 30min to prepare an aqueous solution of 1×10 -3 g / L. The activated bacterial solution of E. coli and S. aureus was diluted to 10 4 CFU / mL for standby.

[0104] At 0h and 72h after the above aqueous solution was placed, 8mL of distilled water was added to a sterile test tube, 1mL of the above aqueous solution and 1mL of the bacterial solution were added, and an aqueous solution containing the bacterial solution of 1×10 -4 g / L was obtained after shaking. The above aqueous solution containing the bacterial solution was removed and uniformly coated on a broth agar plate, which was cultured at 37℃ for 36h, and the growth of the colonies was observed. Each treatment was repeated three times.

[0105] The colonies in the culture dish were counted by plate counting method, and the average number of colonies and the antibacterial rate were calculated, and the specific results are shown in Table 2.

[0106] The antibacterial rate (%) = (A-B) / A×100%.

[0107] In the formula, A is the number of colonies of the blank control group with an antibacterial concentration of 0; B is the average number of colonies of the sample after adding the composite material solution.

[0108] Table 2: Antibacterial rate (%) of each treatment

[0109]

[0110] As can be seen from the data in Table 2, the microencapsulated nanosilver composite material prepared by the method of the present application still has high long-acting antibacterial activity at low concentration. As can be seen from the data of Example 1 and Comparative Examples 1-3, the preparation method of the composite microorganism, the culture medium and the nanosilver all affect the antibacterial effect and antibacterial duration of the nanosilver. As can be seen from the data of Example 1 and Example 4, encapsulating nanosilver can prolong the antibacterial time of nanosilver. As can be seen from the data of Example 4 and Comparative Examples 4-6, the preparation method of the composite microorganism, the culture medium and the nanosilver can affect the antibacterial effect and antibacterial duration of the encapsulated nanosilver composite material. As can be seen from the data of Example 4 and Comparative Example 7, compared with chitosan, using quaternized chitosan K100 can make the encapsulated nanosilver composite material have stronger and longer antibacterial effect.

[0111] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing a microencapsulated nanosilver composite material having a long-acting antibacterial function, characterized by, The preparation method comprises the following steps: (1) fermenting the composite microorganism in a culture medium to obtain a fermentation liquor, and reacting the fermentation liquor with a silver nitrate solution, an emulsifier and a dispersing agent under microwave conditions to obtain a nano-silver solution; the composite microorganism is composed of Bacillus thuringiensis and Leucotrichia algae according to a weight ratio of 2-5:1-3; the culture medium is obtained by homogenizing oats, kiwi fruit, privet fruit, glucose and water according to a weight ratio of (30-40):(20-30):(8-12):(10-30):(200-300); the fermentation temperature is 28-35℃, the pH value is 7.0-8.0, and the fermentation time is 24-48h; (2) mixing and reacting the nano-silver solution obtained in step (1) with a quaternary ammonium chitosan solution, and spray drying to obtain a microencapsulated nano-silver composite material.

2. The production method according to claim 1, characterized by, In step (1), the concentration of the silver nitrate solution is 0.3-0.6mol / L.

3. The production method according to claim 1, characterized by, In step (1), the emulsifier is one or both of polyvinylpyrrolidone K30 and sodium dodecyl sulfate, and the dispersing agent is one or more of gum arabic, gelatin and sodium alginate.

4. The method of claim 1, wherein, In step (1), the microwave power of the reaction is 100-300W, the temperature is 40-60℃, and the time is 20-40min.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass concentration of the quaternary ammonium chitosan solution is 0.1%-5%, and the volume ratio of the nano-silver solution to the quaternary ammonium chitosan solution is 1:2-4.

6. The method of claim 1, wherein, In step (2), the reaction temperature is 35-55℃, the pH value is 4-6, the stirring speed is 300-800r / min, and the time is 30-60min.

7. The preparation method according to claim 1, characterized in that, In step (2), the spray drying temperature is 70-85℃.

8. A microencapsulated nano-silver composite material prepared by the preparation method in any one of claims 1-7.

9. An application of the microencapsulated nano-silver composite material in claim 8 in the preparation of long-acting antibacterial products.

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