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

Abstract

The invention relates to the technical field of antibacterial materials, in particular to a microencapsulated nano-silver composite material with a long-acting antibacterial function and a preparation method of the microencapsulated nano-silver composite material. The preparation method of the microencapsulated nano-silver composite material with the long-acting antibacterial function comprises the steps that a culture medium is fermented through compound microorganisms composed of bacillus thuringiensis and algal algae-eating bacteria, obtained fermentation liquor and a silver nitrate solution containing an emulsifying agent and a dispersing agent are subjected to a microwave reaction, and a nano-silver solution is obtained; and reacting with a quaternized chitosan solution to obtain the microencapsulated nano-silver composite material. The particle size of the nano-silver obtained through the preparation method is only 5.7-9.1 nm, through microencapsulation, the stability of the nano-silver can be improved, silver ions are slowly released, the antibacterial time is prolonged, and the efficient antibacterial effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of nano-biomaterials, and in particular to a microencapsulated nano-silver composite material with long-lasting antibacterial function and a preparation method thereof. Background Art

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

[0003] However, despite the excellent antibacterial properties of nanosilver, it faces a significant bottleneck in practical applications: 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 continuous effective antibacterial effects are often required. However, after nanosilver quickly releases silver ions in the initial stage, the silver ion concentration decreases rapidly over time, and the antibacterial activity also decreases significantly, making it difficult to meet the needs of long-term antibacterial effects. This greatly limits the widespread application of nanosilver in more scenarios with higher requirements for long-term antibacterial effects.

[0004] Therefore, the development of a new antibacterial material of nanosilver and related preparation technology has extremely important practical significance and broad application prospects. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a microencapsulated nano-silver composite material with long-lasting antibacterial function and a preparation method thereof. The microencapsulated nano-silver composite material obtained by the preparation method of the present invention can realize the slow release of silver ions and achieve a long-lasting antibacterial effect.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a microencapsulated nanosilver composite material with long-lasting antibacterial function, comprising:

[0008] (1) fermenting the composite microorganism in a culture medium to obtain a fermentation liquid, reacting the fermentation liquid with a silver nitrate solution, an emulsifier and a dispersant under microwave conditions to obtain a nanosilver solution; the composite microorganism comprises Bacillus thuringiensis and white algae-eating bacteria in a weight ratio of 2-5:1-3;

[0009] (2) mixing the nano-silver solution obtained in step (1) with the quaternized 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 oats, kiwi fruit, Ligustrum lucidum, glucose and water in a weight ratio of (30-40):(20-30):(8-12):(10-30):(200-300); the fermentation temperature is 28-35°C, the pH value is 7.0-8.0, and the fermentation time is 24-48h.

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

[0012] Preferably, the emulsifier in step (1) is one or both of polyvinyl pyrrolidone K30 and sodium lauryl sulfate, and the dispersant is one or more of gum arabic, gelatin and sodium alginate.

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

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

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

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

[0017] The invention also provides a microencapsulated nano silver composite material obtained by the preparation method.

[0018] The present invention also provides the use of the microencapsulated nano-silver composite material in the preparation of a long-acting antibacterial product.

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

[0020] The invention provides a method for preparing a microencapsulated nano-silver composite material, comprising: fermenting a culture medium with a composite microorganism composed of Bacillus thuringiensis and white algae-eating bacteria, subjecting the obtained fermentation liquid to microwave reaction with a silver nitrate solution containing an emulsifier and a dispersant to obtain a nano-silver solution, and then reacting with a quaternized chitosan solution to obtain a microencapsulated nano-silver composite material. The nano-silver obtained by the preparation method of the invention has a particle size of only 5.7-9.1 nm, and through microencapsulation, the stability of the nano-silver can be improved, the silver ions can be slowly released, the antibacterial time can be prolonged, and a high-efficiency antibacterial effect can be achieved. DETAILED DESCRIPTION

[0021] The present invention provides a method for preparing a microencapsulated nanosilver composite material with long-lasting antibacterial function, comprising:

[0022] (1) fermenting the composite microorganism in a culture medium to obtain a fermentation liquid, reacting the fermentation liquid with a silver nitrate solution, an emulsifier and a dispersant under microwave conditions to obtain a nanosilver solution; the composite microorganism comprises Bacillus thuringiensis and white algae-eating bacteria in a weight ratio of 2-5:1-3;

[0023] (2) mixing the nano-silver solution obtained in step (1) with the quaternized chitosan solution for reaction, and spray drying to obtain a microencapsulated nano-silver composite material.

[0024] The culture medium in step (1) of the present invention is preferably obtained by homogenizing oats, kiwifruit, Ligustrum lucidum, glucose and water in 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. Oats are rich in carbohydrates, which can be decomposed into glucose by microorganisms to provide energy for the growth of microorganisms, and are rich in minerals, vitamins and various functional ingredients; kiwifruit is rich in vitamins such as vitamin C and vitamin E, and vitamin C has an antioxidant effect and can protect some oxidation-sensitive components in the culture medium; Ligustrum lucidum can provide a variety of biologically active ingredients, and triterpenoid compounds such as oleanolic acid and ursolic acid can produce stronger antioxidant components after being used by microorganisms, which can protect nanosilver from oxidation in subsequent reactions; glucose can be directly absorbed and used by microorganisms, promoting the rapid increase in the number of microorganisms. The culture medium of the present invention can provide comprehensive nutrients for the composite microorganisms and promote the composite microorganisms to produce more antioxidant metabolites, thereby playing a role in protecting nano silver.

[0025] The Bacillus thuringiensis of the present invention is Bacillus thuringiensis CI CC21298, the white algae-eating fungus is white algae-eating fungus Agarivorans CICC 10798; the activity of the Bacillus thuringiensis is preferably 5-10 billion CFU / g, more preferably 8 billion CFU / g, and the activity of the white algae-eating fungus is preferably 2-5 billion CFU / g, more preferably 3 billion CFU / g. The addition amount of the composite microorganism is 0.5%-2% of the total weight of the oats, kiwi fruit, Ligustrum lucidum and glucose; the fermentation temperature is preferably 28-35°C, more preferably 30°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] During the composite microbial fermentation process of the present invention, the new antioxidant components produced by the microorganisms and the original antioxidant components in the raw materials produce a synergistic effect, which significantly enhances the overall antioxidant capacity of the fermentation liquid. In the subsequent reaction, silver ions can be reduced to obtain nanosilver with a smaller particle size, and the nanosilver can be protected from oxidation in the encapsulation reaction, thereby improving the synthesis efficiency of the encapsulated nanosilver composite material.

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

[0028] The emulsifier in step (1) of the present invention is preferably one or both of polyvinyl pyrrolidone K30 and sodium lauryl sulfate, and the dispersant is preferably one or more of gum arabic, gelatin and sodium alginate. The emulsifier and dispersant are used together to control the formation of spherical nano-silver with uniform particle size and good dispersibility, prevent nano-silver from agglomerating, and improve stability.

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

[0030] The present invention adopts the method of step (1) to make the nano-silver in the system dispersed evenly and have a small particle size, thereby improving the bactericidal ability of the nano-silver.

[0031] The mass concentration of the quaternized chitosan solution in step (2) of the present invention is preferably 0.1%-5%, more preferably 3%; the volume ratio of the nanosilver solution to the quaternized chitosan solution is preferably 1:2-4, more preferably 1:3.

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

[0033] The quaternized chitosan of the present invention is quaternized chitosan 100K, which has good water solubility compared to chitosan, is easier to mix evenly with other substances, is more conducive to forming a stable microcapsule system, has better flexibility and mechanical strength, and has significantly enhanced antibacterial properties.

[0034] The invention embeds nano silver in quaternized chitosan with antibacterial property 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 a long-term antibacterial effect is achieved.

[0035] The invention also provides a microencapsulated nano silver composite material obtained by the preparation method.

[0036] The present invention also provides the use of the microencapsulated nano-silver composite material in the preparation of a long-acting antibacterial product.

[0037] The microencapsulated nano-silver composite material of the present invention can be used in fabrics, food packaging materials, antibacterial coatings of sanitary facilities, filters of air purification equipment, wound dressings, disinfection of medical equipment, oral materials (gutta-percha tips, root canal filling materials, etc.), etc.

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

[0039] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0041] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0042] Example 1

[0043] Preparation of Nanosilver

[0044] (1) Preparation of fermentation broth

[0045] 35 parts by weight of oats, 25 parts by weight of kiwi fruit, 10 parts by weight of Ligustrum lucidum fruit and 20 parts by weight of glucose were mixed evenly, placed in a wall breaking machine, 250 parts by weight of water were added, the wall was broken at 30000 r / min for 5 minutes, maintained at 72° C. for 15 seconds, and cooled to obtain a culture medium;

[0046] Add oats, kiwi fruit, Ligustrum lucidum and 1% of the total weight of glucose composite microorganisms, and ferment at 30°C and pH 7.5 for 36h;

[0047] The composite microorganisms are composed of Bacillus thuringiensis CICC 21298 and Agarivorans CICC 10798 is composed of Bacillus thuringiensis in a weight ratio of 4:2. CICC 21298 has a bacterial activity of 8 billion CFU / g, white algae-eating fungi Agarivorans The bacterial activity of CICC10798 is 3 billion CFU / g;

[0048] (2) Preparation of Nanosilver

[0049] The silver nitrate solution, the polyvinyl pyrrolidone K30 solution and the sodium alginate solution are mixed, and then mixed with the fermentation liquid of step (1), and reacted under microwave conditions of 200 W and 50° C. for 30 min to obtain a nanosilver solution;

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

[0051] Example 2

[0052] Preparation of Nanosilver

[0053] (1) Preparation of fermentation broth

[0054] 30 parts by weight of oats, 20 parts by weight of kiwi fruit, 8 parts by weight of Ligustrum lucidum fruit and 10 parts by weight of glucose were uniformly mixed, placed in a wall breaking machine, 200 parts by weight of water were added, the wall was broken at 33000 r / min for 3 min, maintained at 70° C. for 18 s, and cooled to obtain a culture medium;

[0055] Add oats, kiwi fruit, Ligustrum lucidum and 0.5% of the total weight of the composite microorganisms of glucose, and ferment at 28°C and pH 7.0 for 48h;

[0056] The composite microorganisms are composed of Bacillus thuringiensis CICC 21298 and Agarivorans CICC 10798 is composed of Bacillus thuringiensis in a weight ratio of 2:3. CICC 21298 has a bacterial activity of 10 billion CFU / g, white algae-eating fungus Agarivorans The bacterial activity of CICC10798 is 5 billion CFU / g;

[0057] (2) Preparation of Nanosilver

[0058] The silver nitrate solution, the sodium dodecyl sulfate solution and the gum arabic solution are mixed, and then mixed with the fermentation liquid of step (1), and reacted under microwave conditions of 100 W and 40° C. for 40 min to obtain a nanosilver solution;

[0059] The concentration of the silver nitrate solution is 0.3 mol / L; the concentration of the sodium dodecyl sulfate solution is 0.3 mol / 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 liquid is 1:1.

[0060] Example 3

[0061] Preparation of Nanosilver

[0062] (1) Preparation of fermentation broth

[0063] 40 parts by weight of oats, 30 parts by weight of kiwi fruit, 12 parts by weight of Ligustrum lucidum fruit and 30 parts by weight of glucose were mixed evenly, placed in a wall breaking machine, 300 parts by weight of water were added, the wall was broken at 28000 r / min for 8 minutes, maintained at 72° C. for 13 seconds, and cooled to obtain a culture medium;

[0064] Add oats, kiwi fruit, Ligustrum lucidum and 2% of the total weight of glucose composite microorganisms, and ferment at 35°C and pH 8.0 for 24h;

[0065] The composite microorganisms are composed of Bacillus thuringiensis CICC 21298 and Agarivorans CICC 10798 is composed of Bacillus thuringiensis in a weight ratio of 5:1. CICC 21298 has a bacterial activity of 5 billion CFU / g, white algae-eating fungi Agarivorans The bacterial activity of CICC10798 is 2 billion CFU / g;

[0066] (2) Preparation of Nanosilver

[0067] The silver nitrate solution, the polyvinyl pyrrolidone K30 solution and the gelatin solution are mixed, and then mixed with the fermentation liquid of step (1), and reacted under microwave conditions of 100 W and 40° C. for 40 min to obtain a nanosilver solution;

[0068] The concentration of the silver nitrate solution is 0.6 mol / L; the concentration of the polyvinyl pyrrolidone 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 polyvinyl pyrrolidone K30 solution and the gelatin solution is 1:3:3; the ratio of the total volume of the silver nitrate solution, the polyvinyl pyrrolidone K30 solution and the gelatin solution to the volume of the fermentation liquid is 1:3.

[0069] Comparative Example 1

[0070] The specific implementation is the same as in Example 1, except that the composite microorganism is Lactiplantibacillus plantarum 23489 and Saccharomyces cerevis iae 1263 is composed of Lactiplantibacillus pl antarum in a weight ratio of 4:2 The bacterial activity of 23489 is 8 billion CFU / g, Saccharomyces cerevisiae The preferred bacterial activity of 1263 is 3 billion CFU / g.

[0071] Comparative Example 2

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

[0073] Comparative Example 3

[0074] Equal volumes of 0.48 mol / L silver nitrate solution, 4 mol / L polyvinyl pyrrolidone K30 solution and 54 g / L sodium alginate solution were mixed to obtain a mixed solution; equal volumes of 0.08 mol / L tannic acid solution and 0.02 mol / L sodium citrate solution were stirred and mixed at 60° C., and then quickly transferred into the mixed solution (the ratio of the total volume of the tannic acid solution and the sodium citrate solution to the volume of the mixed solution was 4:1), and the stirring was continued at a constant temperature for 10 min, and the solution was boiled in an oil bath for 20 min to obtain a nanosilver solution.

[0075] Test Example 1

[0076] Nanosilver particle size

[0077] The nanosilver solutions of Examples 1-3 and Comparative Examples 1-3 were filtered respectively, and the separated nanosilver was centrifugally washed 4 times with ethanol and distilled water respectively, and spray-dried at 80° C. to a water content of 5% to be in powder form without obvious particles.

[0078] 2 mg of the dried nanosilver in Examples 1-3 and Comparative Examples 1-3 were respectively added to 1.0 mL of purified water and dispersed evenly, and then placed in a laser particle size analyzer for measurement. The specific results are shown in Table 1.

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

[0080] Group Particle size (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 nanosilver of Examples 1-3 and Comparative Examples 1-3 all have good dispersibility, are spherical, and have uniform particle size distribution. It can be seen from the data of Example 1 and Comparative Examples 1-2 that the use of the composite microorganism and culture medium of the present invention can reduce the particle size of nanosilver. The particle size comparison of Example 1 and Comparative Example 3 shows that the nanosilver prepared by the method of the present invention has a smaller particle size, resulting in a better antibacterial effect.

[0082] Example 4

[0083] Preparation of Microencapsulated Nanosilver Composite Materials

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

[0085] Example 5

[0086] Preparation of Microencapsulated Nanosilver Composite Materials

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

[0088] Example 6

[0089] Preparation of Microencapsulated Nanosilver Composite Materials

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

[0091] Comparative Example 4

[0092] The specific implementation is the same as that of Example 4, except that the nanosilver solution is replaced by the nanosilver solution of Comparative Example 1.

[0093] Comparative Example 5

[0094] The specific implementation is the same as that of Example 4, except that the nanosilver solution is replaced by the nanosilver solution of Comparative Example 2.

[0095] Comparative Example 6

[0096] The specific implementation is the same as that of Example 4, except that the nanosilver solution is replaced by the nanosilver solution of Comparative Example 3.

[0097] Comparative Example 7

[0098] The specific implementation is the same as that of Example 4, except that the quaternized chitosan K100 is replaced by chitosan.

[0099] Test Example 2

[0100] Antibacterial properties of microencapsulated nanosilver composites

[0101] Escherichia coli 10899) and Staphylococcus aureus 21600) to detect the antibacterial properties of the nanosilver of Example 1 and Comparative Examples 1-3 (the nanosilver solution was spray dried to a water content of 5%), and the composite materials of Examples 4-6 and Comparative Examples 4-7.

[0102] Escherichia coli and Staphylococcus aureus were inoculated on nutrient agar, activated at 37°C for 24 h, and suitable single colonies were selected and inoculated into nutrient broth. The culture was incubated at 37°C in a constant temperature shaker until the bacterial solution concentration reached 10 6 CFU / mL, and the activated bacterial solution was obtained.

[0103] The nanosilver of Example 1 and Comparative Examples 1-3 and the composite materials of Examples 4-6 and Comparative Examples 4-7 were ultrasonicated at room temperature for 30 minutes to prepare 1×10 -3 g / L aqueous solution. Dilute the activated bacterial solution of Escherichia coli and Staphylococcus aureus to 10 4 CFU / mL is reserved.

[0104] At 0h and 72h, 8mL of distilled water was added to a sterile test tube, followed by 1mL of the aqueous solution and 1mL of bacterial solution. After sufficient shaking, 1×10 -4 g / L aqueous solution containing bacterial solution. Pipette the aqueous solution containing bacterial solution and evenly spread it on the broth agar plate, incubate at 37°C for 36 hours, and observe the growth of the colonies. Each treatment is repeated three times.

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

[0106] Antibacterial rate (%) = (AB) / A×100%.

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

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

[0109]

[0110] It can be seen from the data in Table 2 that the microencapsulated nanosilver composite material prepared by the method of the present invention can still maintain a high long-term antibacterial activity at low concentrations. It can be seen from the data of Example 1 and Comparative Examples 1-3 that the composite microorganism, culture medium and nanosilver preparation method all affect the antibacterial effect and antibacterial duration of nanosilver. It can be seen from the data of Example 1 and Example 4 that encapsulating nanosilver can extend the antibacterial time of nanosilver. It can be seen from the data of Example 4 and Comparative Examples 4-6 that the composite microorganism, culture medium and nanosilver preparation method all affect the antibacterial effect and antibacterial duration of the encapsulated nanosilver composite material. It can be seen from the data of Example 4 and Comparative Example 7 that the use of quaternized chitosan K100 relative to chitosan can make the encapsulated nanosilver composite material have a stronger and longer-lasting antibacterial effect.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a microencapsulated nanosilver composite material with long-lasting antibacterial function, characterized in that: include: (1) fermenting the composite microorganism in a culture medium to obtain a fermentation liquid, reacting the fermentation liquid with a silver nitrate solution, an emulsifier and a dispersant under microwave conditions to obtain a nanosilver solution; the composite microorganism comprises Bacillus thuringiensis and white algae-eating bacteria in a weight ratio of 2-5:1-3; (2) mixing the nano-silver solution obtained in step (1) with the quaternized chitosan solution for reaction, and spray drying to obtain a microencapsulated nano-silver composite material.

2. The preparation method according to claim 1, characterized in that: The culture medium in step (1) is obtained by homogenizing oats, kiwi fruit, Ligustrum lucidum, glucose and water in a weight ratio of (30-40):(20-30):(8-12):(10-30):(200-300); the fermentation temperature is 28-35°C, the pH value is 7.0-8.0, and the fermentation time is 24-48h.

3. The preparation method according to claim 1, characterized in that: The concentration of the silver nitrate solution in step (1) is 0.3-0.6 mol / L.

4. The preparation method according to claim 1, characterized in that: In step (1), the emulsifier is one or both of polyvinyl pyrrolidone K30 and sodium lauryl sulfate, and the dispersant is one or more of gum arabic, gelatin and sodium alginate.

5. The preparation method according to claim 1, characterized in that: The microwave power of the reaction in step (1) is 100-300W, the temperature is 40-60°C, and the time is 20-40min.

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

7. The preparation method according to claim 1, characterized in that: The reaction temperature of step (2) is 35-55°C, the pH value is 4-6, the stirring speed is 300-800r / min, and the time is 30-60min.

8. The preparation method according to claim 1, characterized in that: The spray drying temperature in step (2) is 70-85°C.

9. A microencapsulated nanosilver composite material obtained according to the preparation method according to any one of claims 1 to 8.

10. Use of the microencapsulated nanosilver composite material according to claim 9 in the preparation of a long-acting antibacterial product.

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